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Assessments of technological developments:Best available techniques (BAT) and limit values

Final Draft

Prepared by:

Katja Kraus (Chair, Germany)Stefan Wenzel (Germany)Grace Howland (Canada)Ute Kutschera (Austria)

Stanislaw Hlawiczka (Poland)André Peeters Weem (The Netherlands)

Chuck French (United States of America)

Submitted to the Task Force on Heavy MetalsUNECE Convention on Long-range Transboundary Air Pollution

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June 14, 2006

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Executive summary

1. The following overview of the most recent technological BAT developments in relation to annex III of the Protocol covers both new and existing stationary sources and is given for each source category as indicated in annex III. Additional information is given for emerging technolo-gies. Techniques already described in annex III are not taken into account for this summary. Further information on techniques with regard to application, environmental performance etc., can be found in the respective chapters.

2. The primary sources of information for this document were the BAT reference documents from the European Integrated Pollution Prevention and Control Bureau (EIPPCB). Other sources of information included the United Nations Environment Program (UNEP) 2002 Global Mercury Assessment, and various technical reports from United States Environmental Protec-tion Agency (U.S. EPA), Environment Canada, and the European Commission. References rel-evant to each chapter are provided at the end of the individual chapters. There may by other sources of information that were not considered.

Table 1: Overview on Most Recent Developments with BAT and other Emissions Control Techniques

Sector BAT according to BREF documents and potential BAT from other references

Emerging Techniques

Combustion of fossil fuels in utility and industrial boilers

Stable combustion conditions (reduce peak emissions)Wet FGD plus particulate matter (PM) control device (ESP or FF) (plus high dust SCR)Injection of sorbent prior to FGD Carbon filter bed filtration of flue gasFor low sulfur fuels (e.g. biomass): FFFor combustion of coal:IGCC

New designs of ESPsImproving the liquid-to-gas ratioWet FGD Tower DesignInjection of activated carbon impregnated with additivesLow-NOx technologies (BAT for NOx-control)Reburning (BAT for NOx-control)Simultaneous control of sulfur dioxide, nitrogen oxides and HgFuel cellsBiomass-fired IGCC

Primary iron and steel in-dustry

Efficient capture and exhaust of emissionsProcessing of ferrous metal oresIncrease the mercury rejection to the tailingSinter plantsFine wet scrubbers or FF with lime additionExclusion of PM from last ESP field from recycling to the sinter strandRecirculation of waste gasPelletisation plantsScrubbing Semi-dry desulfurization and subsequent PM removalBlast furnaces

Direct reduction/ smelt-ing reduction (alterna-tives to the coke oven/BF route)Blast furnacesContinuous steelmakingBasic oxygen steelmak-ing and castingNew reagents in the desulfurization process Foaming techniques at pig iron pre-treatment and steel refining

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Hot stovesCast house PM removalBasic oxygen furnaces:Minimize the presence of mercury in the scrap by removing mercury-bearing components

Secondary iron and steel industry

Minimize the presence of mercury in the scrap by removing mercury-bearing componentsElectric arc furnaceDirect off gas extractionCapture and control of charging and tapping emissions, e.g., canopy hood and baghouse)

Electric arc furnaceComelt EAF / Contiarc furnace / Direct reduc-tion / Liquid iron

Iron foundries

Minimizing fugitive emissionsCupola furnace melting of cast ironImprove the thermal efficiency Divided blast operation (2 rows of tuyères) for cold blast cupo-lasOxygen enrichment of the blast airMinimize the blast-off periods for hot blast cupolasInduction furnace melting of cast iron and steelIncrease furnace efficiency Dry flue-gas cleaningRotary furnace melting of cast ironIncrease the melting efficiencyPost combustionDry PM removal

Primary and secondary non-ferrous metal indus-try

Minimize emissions from materials handling, storage and trans-ferSealed reactors and furnacesProcesses connected to a sulfuric acid plant: Wet scrubber or wet ESPRemoval of mercury from off-gasActivated carbon filterSpray dry systems with downstream FFRemoval of mercury from sulfuric acid Superlig Ion Exchange process Potassium iodide processPrimary and secondary production of copperVarious processes depending on raw materials FF (with lime injection)Scrubbing (if necessary)Secondary production of aluminiumVarious processes depending on raw materialsFF or ceramic filterPrimary and secondary production of lead and zincVarious processes depending on raw materialsFF /wet ESP /wet scrubbing (depending on process)Production of gold

Selenium filter Odda chloride process Primary and secondary production of copperBath smelting ISA Smelt hydro-metallurgical pro-cesses (e.g. leach-sol-vent extraction-electro-win (L:SX:EW) process)Secondary production of aluminiumReuse of filter PMCatalytic filter bagsPrimary and secondary production of lead and zincLeaching processes based on chloride Injection of fine material EZINEX process (direct treatment of EAF dusts)Direct smeltingLead sulfide process

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FF / wet ESP / scrubbing (depending on process)Production of mercuryPhase out primary production of mercury Stop surpluses re-entering the marketProduction of mercury from secondary raw materialsMercury scrubber (Boliden, thiosulphate etc).

BSN process using PM from EAFProduction of gold'J' process Gold production from pyrite concentrateProduction of mercuryProcess with abatement of fine mercury particles

Cement in-dustry

Dry process kiln with multi-stage preheating and precalcination Fluidised bed cement manufacturing Lower exhaust tempera-tureAdsorption on activated carbon

Glass indus-try

ESP or FF (with dry or semi-dry acid gas scrubbing)Dry Injection FF/ Dry Lime Scrubber combination, or wet scrub-berMinimize downstream emissions

Plasma melter

Chlor-alkali industry

PARCOM decision 90/3 of 14 June 1990 (phase-out of the mercury process) was reviewed in 1999-2001 without any changesConversion to membrane cell technology Non-asbestos diaphragm technology Stop surplus of Hg from decommissioning re-entering the mar-ketMinimizing emissions from handling, storage, treatment and disposal of mercury-contaminated wastes Stringent work place practices to reduce emissions, including:1. Use of specific equipment (e.g., smooth interior pipes, fixed

covers, head space routed to ventilation system etc....2. Preventive Operations (e.g., cool electroplate and decom-

poser before opening, keep mercury covered with aqueous liquid at temperature below its boiling point, gas stream cooling to remove mercury from hydrogen stream

Mist eliminatorsScrubbers Adsorption on activated carbon and molecular sievesComplete enclosure of the cell room

Municipal, medical and hazardous waste incin-eration

In some countries, no differentiation between municipal, haz-ardous and medical waste in terms of applied techniques or achievable emission limits.Separate collection and treatment of mercury-containing wastesSubstitution of mercury in productsSorbent injectionFGD Carbon filter beds Wet scrubber with additivesSelenium filters

Heavy metal evapora-tion processHydro-metallurgical treatment + vitrificationMunicipal waste inciner-ation PECK combination process

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Activated carbon injection prior to the ESP or FFActivated carbon or coke filtersSelective catalytic reduction (SCR) Co-incineration of waste and recovered fuel in cement kilnsAvoid Hg entering as an elevated component of the secondary fuel BAT for cement kilnsCo- incineration of waste and recovered fuel in combustion in-stallationsAvoid Hg entering as an elevated component of the secondary fuel Gasification of the secondary fuel Injection of activated carbonBAT for combustion installations

Definition of Acronyms used in Table 1:BAT Best available techniquesBF Blast furnaceBOF Basic oxygen furnaceBREF Best available technique reference documentCFA Circulating fluidized-bed absorberEAF Electric arc furnaceESP Electrostatic precipitatorFF Fabric filterFGD Flue gas desulfurizationIGCC Integrated gasification combined-cyclePM Particulate matterSCR Selective Catalytic Reduction

3. The following overview of the most recent technological ELV developments in relation to annex V of the Protocol covers both new and existing stationary sources and is given for each source category as indicated in annex III. Additional information is given for source categories identified in annex II and heavy metals indicated in annex I of the Protocol for which no ELV is specified in annex V. The current ELVs of annex V are given for comparison, as well as emis-sion levels associated with best available techniques (BAT) from the European BREF docu-ments which are not considered as ELVs. Most sectors cover a wide range of installations with regard to technology and size, and the indicated ranges often comprise several techniques and/or size classes. ELVs for heavy metals are often given for a whole range of heavy metals, so the indicated values may not reflect an ELV for a single pollutant. Additionally, a combina-tion of techniques might be necessary to achieve the indicated BAT associated emission lev-els. For further information, reference is made to the background information.

4. All values are expressed in mg/Nm³, except for the chlor-alkali industry, where values are expressed in g Hg/Mg Cl2 production capacity. All values refer to standard conditions (273.15 K, 101.3 kPa, dry gas) and do not cover start-up and shutdown periods.

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Table 2: Overview on ELVs

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Sector Pollutant ELVsCombustion of fossil fuels in utility and industrial boilers (> 50 MW, solid and liquid fu-els)

PM Annex V 50ELVs in force (new installations) 17-50ELVs in force (existing installations) 20-150BAT (50 – 300 MW, new installations) 5-20BAT (50 – 300 MW, existing installations) 5-30BAT (> 300 MW, new installations) 5-10BAT (> 300 MW, existing installations) 5-20

Cd ELVs in force 0.05-1.1

Pb ELVs in force 0.5-5

Hg ELVs in force 0.01-0.2


PM sinter plants Annex V 50ELVs in force 20-150BAT 10-50

pellet plants Annex V 25ELVs in force 20-150BAT < 10

blast furnace Annex V 50ELVs in force 6.8-150BAT 1-15

other processes ELVs in force 5-150BAT 5-30





PM EAF > 2.5 t Annex V 20ELVs in force 5-20BAT < 5-15

other processes ELVs in force 20-50




Iron foundries

PM ELVs in force 2.3-50BAT 5-20




Primary and secondary non-ferrous metal indus-try

PM production of copper and zinc

Annex V 20ELVs in force 1-50BAT 1-5

production of lead Annex V 10ELVs in force 1-50BAT 1-5

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production. of gold ELVs in force 1-50BAT 1-5

production of mercury ELVs in force 1-50BAT 1-5

other processes ELVs in force 5-50




Cement in-dustry

PM Annex V 50ELVs in force 15-150BAT 20-30




Glass indus-try

PM ELVs in force 5-50BAT 5-30

Cd ELVs in force 0.05-5

Pb Annex V 5ELVs in force 0.5-5BAT <5



Hg new installations

Annex V 0.01ELVs in force 0.0-0.01

existing installations

ELVs in force (legally binding phase out of mercury process) 1 -5.3BAT (total emissions) (phase out of mercury process) 0.21-0.32


PM municipal waste incineration > 3t/h


medical wasteincineration > 1t/h


hazardous waste incineration > 1t/h

Annex V 10ELVs in force 2.4-57BAT 1-5

co-incineration ELVs in force 10-20

Cd municipal waste incineration > 3t/h

ELVs in force 0.03-0.2BAT 0.005-0.05


ELVs in force 0.028-0.2BAT 0.005-0.05


ELVs in force 0.05-0.5BAT 0.005-0.05

co-incineration ELVs in force 0.05

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Pb municipal waste incineration > 3t/h

ELVs in force 0.31-5BAT 0.005-0.5





co-incineration ELVs in force 0.5

Hg municipal waste incineration > 3t/h

Annex V 0.08ELVs in force 0.02-0.2BAT 0.001-0.02


ELVs in force 0.02-0.39BAT 0.001-0.02


Annex V 0.005-0.2ELVs in force 0.001-0.02BAT

co-incineration ELVs in force 0.03-0.05

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Table of contents

INTRODUCTION....................................................................................................13

COMBUSTION OF FOSSIL FUELS IN UTILITY AND INDUSTRIAL BOILERS....17

PRIMARY IRON AND STEEL INDUSTRY.............................................................27

SECONDARY IRON AND STEEL INDUSTRY......................................................35

IRON FOUNDRIES................................................................................................41

PRIMARY AND SECONDARY NON-FERROUS METAL INDUSTRY..................47

CEMENT INDUSTRY.............................................................................................65

GLASS INDUSTRY................................................................................................71

CHLOR-ALKALI INDUSTRY..................................................................................79

MUNICIPAL, MEDICAL AND HAZARDOUS WASTE INCINERATION.................85

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INTRODUCTION

5. The Task Force on Heavy Metals reviewed technological developments with regard to emissions from stationary sources for those heavy metals (HM) listed in annex I to the Proto-col. This report compiles background information on technological developments for each source category of annex II to the Protocol, including:- a compilation of recent developments in best available techniques (BAT) in relation to an-

nex III to the Protocol;- a compilation of current emission limit values (ELVs) in relation to annex V to the Protocol

as well as for source categories identified in annex II and HM indicated in annex I for which no ELV is specified in annex V.

6. The report is structured according to the technical information given in annex III to the Pro-tocol. The following table gives an overview of the chapters of the report and their correspon-dence to the sector description and technical information in annex III and the source categories of annex II to the Protocol.

Table 3: Coverage of sectors in this report

Sector (chapter of the report)

Technical information according to annex III to the Protocol

Source categories according to annex II to the Protocol

Combustion of fossil fuels in utility and industrial boilers

Combustion of fossil fuels in utility and industrial boilers: coal and fuel oil fired boilers, not including gas turbines and stationary engines, and not including the use of waste as a fuel, are con-sidered.

1: Combustion installations with a net rated thermal input exceeding 50 MW


Primary iron and steel industry: the processing of ferrous metal ores to-gether with the primary iron and steel industry are considered. The produc-tion of mercury and gold as well as the roasting and sintering of non-ferrous metal ores are regarded within the primary and secondary non-ferrous metal industry.

2: Metal ore (including sulphide ore) or concen-trate roasting or sintering installations with a capacity exceeding 150 tonnes of sinter per day for ferrous ore or concentrate, and 30 tonnes of sinter per day for the roasting of cop-per, lead or zinc, or any gold and mercury ore treatment.


Secondary iron and steel industry: the secondary iron and steel industry in-cluding electric arc furnaces (EAF) are considered.

3: Installations for the production of pig-iron or steel (primary or secondary fusion, including electric arc furnaces) including continuous casting, with a capacity exceeding 2.5 tonnes per hour.

Iron foundries

Iron foundries: iron foundries, not in-cluding steel and temper foundries, are considered.

4: Ferrous metal foundries with a production capacity exceeding 20 tonnes per day.

Primary and Primary and secondary non-ferrous 5: Installations for the production of copper,

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Sector (chapter of the report)

Technical information according to annex III to the Protocol

Source categories according to annex II to the Protocol

secondary non-ferrous metal in-dustry

metal industry: the processing of non-ferrous metals and their ores is con-sidered.

lead and zinc from ore, concentrates or sec-ondary raw materials by metallurgical pro-cesses with a capacity exceeding 30 tonnes of metal per day for primary installations and 15 tonnes of metal per day for secondary installa-tions, or for any primary production of mercury.

6: Installations for the smelting (refining, foundry casting, etc.), including the alloying, of copper, lead and zinc, including recovered products, with a melting capacity exceeding 4 tonnes per day for lead or 20 tonnes per day for copper and zinc.

Cement in-dustry

Cement industry: the production of ce-ment clinker in fossil fuel fired kilns, not including the use of waste as a fuel, is considered.

7: Installations for the production of cement clinker in rotary kilns with a production capacity exceeding 500 tonnes per day or in other fur-naces with a production capacity exceeding 50 tonnes per day.

Glass in-dustry

Glass industry: the production of glass using lead in the process, including the recycling of lead containing glass, is considered.

8: Installations for the manufacture of glass us-ing lead in the process with a melting capacity exceeding 20 tonnes per day.


Chlor-alkali industry: the chlor-alkali production by the mercury, diaphragm and membrane cell electrolysis pro-cess is considered.

9: Installations for chlor-alkali production by electrolysis using the mercury cell process..


Municipal, medical and hazardous waste incineration: the incineration of municipal, medical and hazardous waste is considered.

10: Installations for the incineration of hazard-ous or medical waste with a capacity exceed-ing 1 tonne per hour, or for the co-incineration of hazardous or medical waste specified in ac-cordance with national legislation.

11: Installations for the incineration of muni-cipal waste with a capacity exceeding 3 tonnes per hour, or for the co-incineration of municipal waste specified in accordance with national le-gislation.

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7. The following acronyms are used throughout the document:BAT Best available techniquesBF Blast furnaceBOF Basic oxygen furnaceBREF Best available technique reference documentCFA Circulating fluidized-bed absorberEAF Electric arc furnaceEIPPCB European Integrated Pollution Prevention and control BureauELV Emission limit valuesESP Electrostatic precipitatorFF Fabric filterFGD Flue gas desulfurizationIGCC Integrated gasification combined-cyclePM Particulate matterSCR Selective Catalytic Reduction

8. The primary sources of information for this document were the BAT reference documents from the European Integrated Pollution Prevention and control Bureau (EIPPCB). Other sources of information included the United Nations Environment Program (UNEP) 2002 Global Mercury Assessment, and various technical reports from the US Environmental Protection Agency (US EPA), Environment Canada, and the European Commission. References relevant to each chapter are provided at the end of the individual chapters. There may by other sources of information that were not considered.

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COMBUSTION OF FOSSIL FUELS IN UTILITY AND INDUSTRIAL BOILERS

Background

9. This category covers the combustion of fossil fuels in utility and industrial boilers. Annex II of the Protocol limits the coverage to combustion installations with a net rated thermal input ex-ceeding 50 Megawatts (MW). According to Annex III, Best Available Techniques (BATs) are considered for coal and fuel oil fired boilers.

10. The combustion of biomass and peat are not currently taken into account in annex III but may be a relevant source of heavy metal emissions. Therefore, additional information is given for these installations. The co-incineration of waste in combustion installations is treated within the category municipal, medical and hazardous waste incineration.

11. According to Annex III, BAT to reduce emissions of heavy metals, except mercury, include the reduction in fuel use and the combustion of natural gas or alternative fuels with a low heavy metal content, the use of electrostatic precipitators or fabric filters. Further emission reduction may be achieved by integrated gasification combined-cycle (IGCC) power plant technology, the beneficiation (washing or bio-treatment) of coal, and the application of techniques to reduce emissions of nitrogen oxides, sulphur dioxide and particulates. No BAT for mercury removal is identified in Annex III.

Best Available Techniques based on the EIPPCB BAT reference (BREF) document and potential BATs from other recent publications

12. About half of the electricity generated worldwide is produced from different fossil fuels, with 30 % being generated from coal. The combustion process leads to the generation of emissions to air which are considered to be one of the major sources of air pollution. The emission of heavy metals results from their presence as a natural component in fossil fuels and are mostly released as compounds in association with particulates. Therefore, BAT to reduce the emis-sions of heavy metals is generally the application of high performance dedusting devices such as electrostatic precipitators or fabric filters. However, mercury is at least partly and up to 90 % present in the vapor phase and its collection by particulate matter control devices is highly vari-able. For electrostatic precipitators (ESPs) or fabric filters (FFs) operated in combination with flue gas desulfurization (FGD) techniques, an average removal rate of 75 % and 90 % in the additional presence of high dust Selective Catalytic Reduction (SCR) devices can be obtained for Hg, depending on the temperature of the filter system and the characteristics of the com-busted coal, e.g., char/carbon content, chlorine content, etc..

13. BAT for preventing releases of particulate matter (PM) from the unloading, storage and handling of solid and liquid fuels and also additives such as lime and limestone are:- using loading equipment that minimises the height of fuel drop to the stockpile- using water spray systems for stockpiles, where applicable- covering stockpiles- grassing over long-term storage areas of coal- for lignite, the direct transfer via belt conveyors or trains from the mine to the storage area- placing transfer conveyers in safe areas aboveground so that they are not damaged- using cleaning devices for conveyer belts

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- using enclosed conveyers with well designed extraction and filtration equipment on transfer points

- rationalising transport systems- using good design and construction practices and adequate maintenance- for lime and limestone, having enclosed conveyers, pneumatic transfer systems and silos

with well designed extraction and filtration equipment on transfer points

Combustion of coal and lignite

14. For the fuel pretreatment of coal and lignite, blending and mixing of fuels can be part of BAT, in order to ensure stable combustion conditions and to thus reduce peak emissions. Switching fuel to a fuel with a better environmental profile can also be regarded as BAT. If coal cleaning is carried out prior to combustion, data from the US Department of Energy indicate that typically 10 – 50 % of the mercury in coal can be removed by the cleaning process alone. The same sources indicate that removal of Cd and Pb can reach even 80%.

15. For the combustion of coal and lignite, pulverized combustion, fluidized bed combustion as well as pressurized fluidized bed combustion and grate firing are all BAT for new and existing plants. Grate firing should preferably only be applied to new plants with a rated thermal input below 100 MW. Pressurized gasification in an integrated gasification combined-cycle (IGCC) is a high efficiency technology that reduces emissions from large scale power production based on solid fuels. Power plants based on coal gasification have been in operation in the USA since 1983 (Kingsport, Tennessee) and IGCC installations have been in use in the USA since 1995 (Polk, Florida) and in the Netherlands since 1994 (Buggenum). Since then several more in-stallations have been commissioned in the USA and Europe. For more information see: http://www.clean-energy.us.

16. For dedusting off-gases from coal- and lignite-fired new and existing combustion plants, BAT is the use of an ESP or a FF, where a FF normally achieves emission levels below 5 mg/m³. Furthermore, the best levels of mercury control are generally achieved by emission control systems (e.g. FGD plus particulate control device) that use FFs. Cyclones and mechan-ical collectors alone are not BAT, but they can be used as a pre-cleaning stage. BAT associ-ated emission levels for dust are lower for combustion plants over 100 MWth, especially over 300 MWth, because the wet FGD technique which is already a part of the BAT conclusion for desulphurisation also reduces particulate matter (PM).

17. All solid fuels such as coal and lignite have a certain concentration of trace elements such as heavy metals. Basically most of the heavy metals evaporate in the combustion process and condensate later onto the surface of the particulate matter (i.e. fly ash). Therefore, BAT to re-duce the emissions of most heavy metals from flue-gases of coal- and lignite-fired combustion plants is to use a high performance ESP (dust reduction rate >99.5%) or a FF (dust reduction rate >99.95%, below 5 mg/m³). With mercury in particular, the capture efficiencies of these sys-tems heavily depend on the speciation of the mercury in, and the fly ash content of, the flue gas. Therefore, for some plants using high performance ESP or FF, the capture of mercury on fly ash can be enhanced by switching or blending the combusted coals to achieve a higher car-bon/char, higher chlorine, or lower mercury content in the combusted coal or by introducing carbon/activated carbon into the flue upstream of the ESP or FF.

18. Mercury has a high vapour pressure at the typical control device operating temperatures, and its collection by particulate matter control devices is highly variable. Taking into account that spray dryer FGD scrubbers and wet lime/limestone scrubbers are regarded as BAT for the

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http://www.clean-energy.us/

http://www.clean-energy.us/

reduction of sulfur dioxide (SO2) for larger combustion plants, relatively low mercury (Hg) emis-sion levels can also be achieved. For the reduction and limitation of Hg emissions, the best levels of control are generally obtained by emission control systems that use FFs and ESPs, where high efficiency ESPs show good removal of Hg (bituminous coal) at temperatures below 130 °C. It appears that little Hg can be captured in hot-side ESPs (installed upstream of the air heater). The best levels of control are generally obtained by emission control systems that use FFs. However, life time of fabric filters is very dependent upon the working temperature and their resistance to the chemical attack by corrosive elements in exhaust gases.

19. Dry FGD systems are already equipped to control emissions of SO2 and PM. Wet FGD sys-tems are typically installed downstream of an ESP or FF. Wet limestone FGD scrubbers are the most commonly used scrubbers on coal-fired utility boilers. These FGD units are expected to capture more than 90 per cent of the ionic mercury (Hg2+) in the flue gas entering the scrub-ber. Consequently, existing wet FGD scrubbers may lower Hg emissions between 20 and 80 %, depending on the speciation of Hg in the inlet flue gas. Improvements in wet scrubber performance in capturing Hg depend primarily on the oxidation of elemental mercury (Hg0) to Hg2+. This may be accomplished by (i) the injection of appropriate oxidizing agents or (ii) the in-stallation of fixed oxidizing catalysts upstream of the scrubber to promote oxidation of ele-mental mercury Hg0 to water soluble species (such as Hg2+). An alternative strategy for con-trolling Hg emissions from wet FGD scrubbing systems is to inject sorbents upstream of the PM control device. Wet scrubbers installed primarily for mercury cost between $76,000 and $174,000 per pound of mercury removed.

20. For FFs or ESPs operated in combination with FGD techniques, such as wet limestone scrubbers, spray dryer scrubbers or dry sorbent injection, an average removal rate of 75 % or 90 % in the additional presence of SCR can be obtained. The reduction rate when firing sub-bi-tuminous coal or lignite is considerably lower and ranges from 30 – 70%. The lower levels of Hg capture in plants firing sub-bituminous coal and lignite are attributed to the low fly ash car-bon content and the higher relative amounts of gaseous Hg in the flue gas from the combustion of these fuels.

21. Additional mercury control can be achieved by injection of a sorbent (carbon- and/or cal-cium-based) prior to the flue gas treatment system. The used carbon and attached waste products are captured by existing PM controls, such as electrostatic precipitators or bag-houses. The US test programs have shown mercury removals of 50 to over 95 percent, de-pending on the carbon feed rate. The U.S. Environmental Protection Agency (EPA) estimates it would cost between $67,700 and $70,000 per pound to achieve a 90% control level. A recent presentation at the Air Quality conference by the United States Department of Energy (DOE) noted that the preliminary economic analysis of field testing data indicates that good progress is being made to reducing the indicated costs by 25 – 50%. Factors likely to influence the ef-fectiveness and cost-effectiveness of activated carbon include: flue gas temperature (flue gas temperature to preferably be below 150 °C); the amount of carbon injected; particulate control equipment design; the amount, concentration, and species of mercury in the flue gas; the con-tact between the carbon and mercury (efficient distribution is needed for the carbon to absorb the mercury); the type of carbon used (e.g., activated carbon that is chemically impregnated with sulphur, iodide, chloride or calcium hydroxide may be more effective by 25 – 45% than non-impregnated activated carbon, particularly when most of the mercury is in elemental form) (U.S. EPA, 2000).

22. Alternatively to carbon injection, the flue gas can be distributed throughout a carbon filter bed. Carbon filter bed technology is assumed by U.S. EPA to remove 80 – 90% of the mercury

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in flue gas at two large (generic) individual facilities at a cost of $33,00 to $38,000 per pound of mercury removed.

23. Depending on the plant and coal used, periodic monitoring of Hg at frequency of at least every third year up to continuous monitoring is recommended to confirm the effectiveness of a chosen BAT. Continuous monitoring of Hg allows for the possibility of maximizing the capture efficiency of a chosen BAT over short periods of time. Total Hg emissions need to be moni-tored in addition to the speciation of the mercury, i.e., concentration of the elemental, ionized mercury and the Hg present as part of the particulate matter. A mass balance approach is rec-ommended where the mercury in the coal and ash are monitored as well as the emissions from the stack and all analyses are done by accredited laboratories.

24. The least costly retrofit options for the control of Hg emissions from units with ESP or FF are believed to include:- The modification of dry FGD systems by the use of appropriate sorbents for the capture of

Hg and other air toxics is considered to be the easiest retrofit problem to solve.- Injection of a sorbent upstream of the ESP or FF. Cooling of the stack gas or modifications

to the ducting may be needed to keep sorbent requirements at acceptable levels;- Injection of a sorbent between the ESP and a pulse-jet FF retrofitted downstream of the

ESP. This approach will increase capital costs but reduce sorbent costs;- Installation of a semi-dry circulating fluidized-bed absorber (CFA) upstream of an existing

ESP used in conjunction with sorbent injection. It is believed that CFAs can potentially con-trol Hg emissions at lower costs than those associated with the use of spray dryers.

25. Preliminary annual costs of Hg controls using powdered activated carbon (PAC) injection have been estimated based on recent pilot-scale evaluations with commercially available ad-sorbents. These control costs range from 0.03 to 0.4 US cents/kWh, with the highest costs as-sociated with plants having hot-side (HS) ESPs. For plants representing 89 % of current capa-city and using controls other than HS- ESPs, the costs range from 0.03 to 0.2 US cents/kWh. Assuming a 40 % reduction in sorbent costs by the use of a composite lime-PAC sorbent for Hg removal, cost projections range from 0.02 to 0.2 US cents/kWh, with higher costs again be-ing associated with plants using hot-side ESPs.

Combustion of liquid fuels

26. For dedusting off-gases from new and existing liquid fuel-fired combustion plants, BAT is the use of an ESP or a FF. Cyclones and mechanical collectors alone are not BAT, but they can be used as a pre-cleaning stage. BAT associated emission levels for dust are lower for combustion plants over 300 MWth because the FGD technique that is part of the BAT conclu-sion for desulphurisation also reduces particulate matter.

27. Liquid fuels, especially heavy fuel oil, typically contain heavy metals, in particular Vanadium and Nickel. Basically most of the heavy metals evaporate in the combustion process and con-densate later in the process on the surfaces of the particulate matter (e.g. fly ash). The ESP is the most used technique for dedusting off-gases from heavy fuel oil firing. The FF is also an applied technique but less important because of the elevated risk of fire, which is reduced if the FF is applied in combination with FGD. Therefore, BAT to reduce the emissions of dust and heavy metals are the use of high performance ESPs (reduction rate >99.5%) or, taking into ac-count the risk mentioned above, a FF (reduction rate >99.95%). Wet scrubbers installed pri-marily for mercury cost between $76,000 and $174,000 per pound of mercury removed.

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28. According to the BREF document, periodic monitoring of heavy metals is BAT. A frequency of every year up to every third year, depending on the kind of liquid fuel used, is recommended. Total Hg especially needs to be monitored and not only the part bound to particulate matter.

Combustion of biomass and peat

29. For the pretreatment of biomass, in particular for wood, classification based on the size and the contamination are BAT, in order to ensure stable combustion conditions, to reduce the amount of unburned fuel in the ash, and thus to reduce peak emissions. In case the wood used is contaminated, it is BAT to know the type of contamination of the wood and an analytical knowledge of the contaminants for each load that arrives to the power plant.

30. For the combustion of biomass and peat, pulverised combustion, fluidised bed combustion as well as spreader stoker grate-firing technique for wood and the vibrating, water-cooled grate for straw-firing are BAT. Pulverised peat combustion plants are not BAT for new plants.

31. For dedusting off-gases from biomass- and peat-fired new and existing combustion plants, BAT is the use of bag-houses with FF or an ESP. When using low sulphur fuels such as biomass, the potential for reduction performance of ESPs is reduced with low flue-gas SO2 concentrations. In this context, the FF, which leads to dust emissions around 5 mg/m³, is the preferred technical option to reduce dust emissions. Cyclones and mechanical collectors alone are not BAT, but they can be used as a pre-cleaning stage.

32. Biomass and peat have certain concentrations of trace elements such as heavy metals. Ba-sically most of the heavy metals evaporate in the combustion process and condensate later onto the surface of the particulate matter (fly ash). Therefore, BAT to reduce the emissions of heavy metals from flue-gases of biomass- and peat-fired combustion plants is to use a FF (re-duction rate >99.95%) or a high performance ESP (reduction rate >99.5%), where the FF should be seen as the first choice for dedusting.

Emerging techniques

33. Research so far has indicated that the most cost-effective approach to mercury control may be an integrated multi-pollutant (SO2, NOx, PM, and mercury) control technology.

34. Recent data suggests that new designs of ESPs can achieve 99.8% PM reductions.

35. The wet scrubber efficiency for mercury removal can be increased by- Adding lime or limestone: It has been assumed that if lime or limestone is added to the

scrubber to increase the percentage of SO2 removed, the same percentage increase in the amount of oxidized mercury removed would occur (about 18%). For units with existing scrubbers, cost estimates range from $62,000-$258,000 per pound, with a reduction poten-tial of 30 pounds/year.

- Improving the Liquid-to-Gas Ratio. In two separate pilot studies, increasing the liquid-to-gas ratio from 40 gallons/1000 acf (actual cubic feet) to 125 gallons/1000 acf increased the re-moval efficiency of oxidized mercury from 90 percent to 99 percent.

- Wet FGD Tower Design. Research has shown that tray tower or open spray tower designs can be effective in removing oxidized mercury from boiler flue gas. The tray tower design removed from 85 to 95 percent of the total mercury (where the composition of the flue gas

23

was mostly oxidized mercury). The open spray tower design removed from 70 to 85 percent of the total mercury.

- Injection of activated carbon impregnated with addings increasing adsorption capacity. Apart from sulfur, iodide, chloride or calcium compounds other impregnating agents can be used like nobel metals, titania and selenium.

36. Low NOx technologies are also likely to reduce mercury emission in the exhaust gases due to the lower operating temperatures. However, while some sources indicate that a reasonable reduction can be achieved, other preliminary results of staged combustion in atmospheric fluid-ized bed combustion (AFBC) units indicated that low-NOx had little effect on trace element emissions.

37. Reburning: This NOx control technology leads to an increased fly ash carbon content and thus enhances the mercury adsorption capacity of fly ash. While increased mercury capture has been shown to occur with increased fly ash carbon, this phenomenon has not been used in commercial practice for the control of mercury emissions, and it should be considered a poten-tial control option that might be available in the future.

Combustion of coal and lignite

38. Simultaneous control of SOx, NOx and mercury: This flue-gas treatment system, which is under demonstration in the U.S., is a gas-phase oxidation process to simultaneously capture up to 99 % of the nitrogen and sulphur oxides as well as basic vapours and heavy metals (100 % of mercury). Capture rates of up to 99 % SOx and 98 % NOx were demonstrated at lab-oratory level over a wide range of temperatures found in flue-gases. Engineering cost esti-mates for the construction of a full scale 500 MW power plant installation is 30-50 % lower in capital costs and with 1/6th operating costs compared to limestone/SCR. Further advantages of the system are: no lime/limestone is used, no CO2-emissions, no catalysts are used, reagent is recycled, proven co-product technologies, system can be retrofitted on most plants.

Combustion of liquid fuels

39. Fuel cell applications are expected to be a future technique for clean liquid fuels. At the mo-ment, the size of the pilot plants is small compared to large combustion plants.

Combustion of biomass and peat

40. IGCC: Pressurized gasification in an integrated gasification combined-cycle (IGCC) is one of the high efficiency technologies which could reduce emissions from large scale power pro-duction based on solid fuels. Peat is an ideal fuel for gasification because of its high volatile content. A demonstration plant for biomass-fired IGCC is under construction in Sweden. The gasification of straw has only been tested successfully when done together with coal.

Co-combustion of waste and recovered fuel

41. It is expected that in future, due to the extra experience being gained with pretreatment and abatement techniques, the degree of co-combustion will be increased above the level of 10 % on a thermal basis.

24

Emission Limit Values

42. The Protocol on Heavy Metals includes an ELV for particulate emissions for solid and liquid fuels of 50 mg/m³ (referring to 6% O2 and 3% O2 in the flue gas, respectively). For the heavy metals covered by the Protocol no ELV is specified.

43. The following table gives an overview on current ELVs implemented by the Parties. Infor-mation was compiled using Parties’ responses to question 44 of the 2004 questionnaire on Strategies and Policies for Compliance Review and additional information by national experts. For comparison, the table also includes BAT associated emission levels as indicated in the Eu-ropean BREF document. All values are expressed in mg/Nm³ referring to standard conditions (273.15 K, 101.3 kPa, dry gas) and do not cover start-up and shutdown periods except stated otherwise. Application ranges normally refer to thermal energy input.

Table 4: ELVs for the combustion of fossil fuels in utility and industrial boilers (in mg/Nm³ unless

stated otherwise)

Country or other refer-

ence

ELV Remarks

ELV for PM emissions

Protocol (Annex V)

> 50 MW 50 solid (6% O2) and liquid (3% O2) fuels; continuous (daily) and dis-continuous measurements (hourly average)

Austria > 50 MW 50> 50 MW 35> 50 MW 30

solid fuels (6%O2, wood 13% O2)liquid fuels except light fuel oil (3% O2)light fuel oil (3% O2)continuous (daily) and discontinuous measurements (half-hourly average)

Belgium > 50 MW 150

> 50 MW 50

solid and liquid fuels, existing installations built before 01/07/87 (Flanders only)solid and liquid fuels, all other installationsdiscontinuous (Flanders only, each value) or continuous measure-ments (daily average).

Bulgaria < 500 MW 100> 500 MW 50

505

solid fuels (6% O2)

liquid fuels (3% O2)gaseous fuels 3%O2Existing installations.: monthly and yearly mean, new installations. Hourly and daily mean values.

Canada > 25 MWel 20-25 0.095 kg/MWh net energy output (approximately 9 ng/J heat in-put); combustion of solid, liquid, or gaseous fuel; new installations, 6% O2

25

Czech Republic

50< 500 MW 100> 500 MW 5050-100 MW 50> 100 MW 30

5

liquid fuels, existing installationssolid fuels, existing installations

solid and liquid fuels, new installations

gaseous fuels, new and existing installations

Finland > 50 MW 50/30 6%/3% O2; existing installations as of 01/01/2008

Germany >50 MW 20 all installations; solid and liquid fuels except light fuel oil; daily av-erage; for light fuel oil: soot level 1

Nether-lands

20 daily average

Slovakia 50

Slovenia 50-500 MW 100≥ 500 MW 50> 50 MW 5050-100 MW 50> 100 MW 30

For coal burning (6 % O2), existing installations

liquid fuels (3% O2); existing installationscoal burning (6 % O2) and liquid fuels (3% O2); new installations

as of 01/01/2008

Switzerland 50 all installations if mass flow > 0.5 kg/h

United States of America

17

35

82

For new utility boilers > 25 MW, the PM ELV = 6.4 ng/J (which is equivalent to 17 mg/m3 at 6% O2), or sources can meet a 99.9% reduction.For new industrial boilers > 3 MW, the PM ELV = 13 ng/J (which is equivalent to 35 mg/m3 at 6% O2)For existing industrial coal-fired boilers > 3 MW, the PM ELV = 30.3 ng/J (which is equivalent to 82 mg/m3 at 6% O2)

BAT ac-cording to BREF doc-

ument

50-100 MW 5-3050-100 MW 5-20100-300 MW 5-25100-300 MW 5-20> 300 MW 5-20> 300 MW 5-10

all fuels, existing installationsall fuels, new installationscoal and lignite and liquid fuels; existing installationsall fuels: new installations; biomass and peat: also existing instal-lationsall fuels: existing installations; biomass and peat: also new instal-lationscoal and lignite and liquid fuels; new installationssolid fuels: 6% O2, liquid fuels: 3% O2

ELV for Cd emissions

Belgium 0.2 all installations if total load ≥ 1 g/h; common ELV for Cd, Hg, Th and their compounds; discontinuous measurements.

Denmark > 5 MW 0.1 hard coal; hourly average, 10% O2

France > 20 MW 0.05 new and existing installations (as of 01/01/2008); common ELV for Cd, Hg, Tl: 0.1

Germany > 50 MW 0.05 all installations; liquid fuels except light fuel oil; discontinuous measurements; half hour average

26

Switzerland 0.1 all installations if mass flow > 0.5 g/h


1.1 ELV for Total Selected Metals (i.e., 8 metals including lead and cadmium) for existing industrial boilers is 0.001 lb/million Btu (about 0.43 ng/J) or about 1.1 mg/m3.

ELV for Pb emissions

Belgium 5 all installations if total load ≥ 25 g/h; common ELV for Sb, Pb, Cr, Co, Cu, Mn, Pt, V, Sn and their compounds. Discontinuous meas-urements.

Denmark > 2/5 MW 5 heavy fuel oil > 2 MW; hard coal > 5 MW; common ELV for Ni, V, Cr, Cu, Pb; hourly average (10% O2)

France > 20 MW 1 new and existing installations (as of 01/01/2008)

Germany > 50 MW 0.5 all installations; liquid fuels except light fuel oil; discontinuous measurements; half hour average

Switzerland 5 all installations if mass flow > 25 g/h


1.1 ELV for Total Selected Metals (i.e., 8 metals including lead and cadmium) for existing industrial boilers is 0.001 lb/million Btu (about 0.43 ng/J) or about 1.1 mg/m3.

ELV for Hg emissions

Belgium 0.2 all installations if total load ≥ 1 g/h; common ELV for Cd, Hg, Th and their compounds. Discontinuous measurements.

Denmark > 2/5 MW 0.1 heavy fuel oil > 2 MW; hard coal > 5 MW; hourly average (10% O2)

France > 20 MW 0.05 new and existing installations (as of 01/01/2008); common ELV for Cd, Hg, Tl: 0.1

Germany > 50 MW 0.03 all installations; solid fuels; daily average

Switzerland 0.2 all installations if mass flow > 1 g/h


0.01 Mercury ELV for existing industrial boilers is 9 lb/trillion Btu (about 0.004 ng/J) heat input or about 0.01 mg/m3.

References

EC 2001Ambient air pollution by mercury - Position Paper. European Communities, 2001.

EIPPCB 2005Integrated Pollution Prevention and Control: Reference Document on Best Available Tech-niques for Large Combustion Plants. European IPPC Bureau, Sevilla: May 2005.

Environment Canada 2003New Source Emission Guidelines for Thermal Electricity Generation:, Canada Gazette, Part I, January 4, 2003

27

U.S. EPA 2000Great Lakes Binational Toxics Strategy: Draft Report for Mercury Reduction Options. United States Environment Protection Agency, September 2000.

UNECE 2002Control of Mercury Emissions from Coal-Fired Electric Utility Boilers. United Nations Economic Commission for Europe, Economic and Social Council, July 2002.

UNEP (2002)Global Mercury Assessment. United Nations Environmental Programme. UNEP Chemicals. December 2002.

U.S. EPA, 2004National Emission Standards for Hazardous Air Pollutants for Industrial/Commercial/Institu-tional Boilers and Process Heaters: Final Rule. 13 September 2004.

U.S. EPA, 2006New Source Performance Standard (NSPS) for Utility Boilers. April 2006.

28

PRIMARY IRON AND STEEL INDUSTRY

Background

44. This category covers the processing of ferrous metal ores or concentrates with a capacity exceeding 150 tonnes of product per day, and installations for the production of pig iron or steel, including continuous casting, with a capacity exceeding 2.5 tonnes per hour. According to annex III of the Protocol, BATs are considered for sinter and pellet plants, blast furnaces (BF) and basic oxygen furnaces (BOF) with subsequent casting, that typically constitute an in-tegrated steel work. The secondary iron and steel industry including electric arc furnaces is considered within the secondary iron and steel industry, while the production of mercury and gold and other processing of non-ferrous metals is considered within the primary and sec-ondary non-ferrous metal industry.1

45. According to Annex III, fabric filters should be used whenever possible; reducing the dust content to less than 20 mg/m³ (hourly average). If conditions make this impossible, electrostatic precipitators and/or high-efficiency scrubbers may be used, reducing the dust content to 50 mg/m³. Many applications of fabric filters can achieve much lower values. When using BAT as described in annex III in the primary iron and steel industry, the total specific emission of dust directly related to the process can be reduced to the following levels:- Sinter plants 40 - 120 g/Mg- Pellet plants 40 g/Mg- Blast furnace 35 - 50 g/Mg- BOF 35 - 70 g/Mg.Direct reduction and direct smelting are under development and may reduce the need for sinter plants and blast furnaces in the future.


46. In integrated steelworks, sinter plants and steelworks dominate the overall emissions for most atmospheric pollutants including heavy metals. Although big efforts have been made to reduce emissions, the contribution of the sector to the total emissions to air is considerable for a number of pollutants, especially for dust, some heavy metals and PCDD/F. The information below is largely based on the European BREF document (EIPPCB 2001).

47. The reduction and capture of fugitive emissions is important since fallout and re-entrain-ment (e.g., from nearby roadways and parking lots) may contribute significantly to heavy metal loading on the surrounding area and beyond. An emission limit for a control system exhaust becomes meaningless if a significant percentage of emissions are not captured by the control system in the first place.

1 The coverage is in accordance with the technical information given in Annex III to the Protocol, whereas the category description as given in Annex II would cover different activities.

29

Processing of ferrous metal ores

48. Use of conventional controls to lower mercury emissions does not prevent mercury pollu-tion permanently because it collects the mercury and transfers it to scrubber water which is then recycled back to the beneficiation (extraction) process. However, some mercury that is scrubbed out of the gas flows into the tailing basin, attaches to solids and settles out in the basin. There is little biological activity in the solids that settle, therefore re-volatilization of mer-cury should not occur.

49. One option is to make plant area modifications to increase mercury rejection to the tailing and reduce the recycling effect of mercury in the beneficiation process. This option calls for modifying the ore concentrating process to increase the mercury rejection to the tailing and for routing the scrubber water outside of the process to reduce the recycling effect of mercury in the beneficiation process. Increases in mercury separation in the iron concentration process will most likely come from improving the weight recovery of iron through additional stages of grinding and flotation. Flotation as well as increased sulfide levels in the ore may also increase the amount of mercury that is rejected to the tailing.

Sinter plants

50. For sinter plants, the following techniques or combination of techniques are considered as BAT (according to the BREF) with regard to heavy metals and dust emissions for both new and existing installations:a) Waste gas de-dusting by application of:

- Advanced electrostatic precipitation (ESP) (moving electrode ESP, ESP pulse system, high voltage operation of ESP …) or

- Electrostatic precipitation plus fabric filter or- Pre-dedusting (e.g. ESP or cyclones) plus high pressure wet scrubbing system.Using these techniques, dust emission concentrations < 50 mg/Nm3 are achieved in nor-mal operation. In case of application of a fabric filter, dust emissions of 10-20 mg/Nm3 are achieved.

b) Minimisation of heavy metal emissions by:- Use of fine wet scrubbing systems in order to remove water-soluble heavy metal chlo-

rides, especially lead chloride(s) with an efficiency of > 90% or a bag filter with lime ad-dition;

- Exclusion of dust from last ESP field from recycling to the sinter strand, dumping it on a secure landfill (watertight sealing, collection and treatment of leachate), possibly after water extraction with subsequent precipitation of heavy metals in order to minimise the quantity to dump.

c) Recirculation of a part of the waste gas, if sinter quality and productivity are not significantly affected.

51. Total costs of implementing fabric filtration for one representative sinter plant are 3000 to 16000 Euro p.a.

52. It is recommended that an environmental performance indicator for the sintering operation be less than 150 grams of particulate matter per tonne of sinter produced for existing iron sinter plants and 100 grams of particulate matter per tonne of sinter produced for modified or new iron sinter plants [Lemmon 2004].

30

53. Best environmental practices for the minimization of emissions from the sinter strand opera-tion include:a) enclosure and/or hooding, where appropriate, with emission controls, of the sinter strand

operations that are potential sources of fugitive emissions;b) operating practices that minimize fugitive emissions that are not amenable to enclosure or

hooding;

Pelletisation plants

54. For pelletisation plants, the following techniques or combination of techniques are consid-ered as BAT (according to the BREF) with regard to heavy metals and dust emissions for both new and existing installations:

a) Efficient removal of particulate matter from the induration strand waste gas, by means of:

- Scrubbing or- Semi-dry desulphurisation and subsequent de-dusting (e.g. gas suspension absorber

(GSA)) or any other device with the same efficiency.Achievable removal efficiency for particulate matter: >95%; corresponding to achievable concentration of < 10 mg dust/Nm³.

Blast furnaces

55. For blast furnaces, the following techniques or combination of techniques are considered as BAT (according to the BREF) with regard to heavy metals and dust emissions for both new and existing installations:a) Hot stoves: emission concentration of dust <10 mg/Nm3 (related to an oxygen content of

3%) can be achievedb) Blast furnace gas treatment with efficient de-dusting: Coarse particulate matter is preferably

removed by means of dry separation techniques (e.g. deflector) and should be reused. Subsequently fine particulate matter is removed by means of:- a scrubber or- a wet electrostatic precipitator or- any other technique achieving the same removal efficiency;A residual particulate matter concentration of < 10 mg/Nm3 is possible.

c) Cast house de-dusting (tap-holes, runners, skimmers, torpedo ladle charging points); Emis-sions should be minimised by covering the runners and evacuation of the mentioned emis-sion sources and purification by means of fabric filtration or electrostatic precipitation. Dust emission concentrations of 1-15 mg/Nm3 can be achieved. Regarding fugitive emissions 5-15 g dust/t pig iron can be achieved; thereby the capture efficiency of fumes is important.

d) Fume suppression using nitrogen (in specific circumstances, e.g. where the design of the casthouse allows and nitrogen is available).

Basic oxygen steelmaking and casting

56. For oxygen steel making including hot metal pre-treatment, secondary metallurgical treat-ment and continuous casting, the following techniques or combination of techniques are con-sidered as BAT (according to the BREF) with regard to heavy metals and dust emissions for both new and existing installations:a) Particulate matter abatement from hot metal pre-treatment (including hot metal transfer pro-

cesses, desulphurisation and deslagging), by means of:- Efficient capture and exhaust;

31

- Subsequent purification by means of fabric filtration or ESP.Dust emission concentrations of 5-15 mg/Nm³ are achievable with bag filters and 20-30 mg/Nm³ with ESP.

b) BOF gas recovery and primary de-dusting, applying:- Suppressed combustion and- Dry electrostatic precipitation (in new and existing situations) or- Scrubbing (in existing situations).Collected BOF gas is cleaned and stored for subsequent use as a fuel, if economical feasi-ble or with regard to appropriate energy management. In some cases, it may not be eco-nomical or, with regard to appropriate energy management, not feasible to recover the BOF gas. In these cases, the BOF gas may be combusted with generation of steam. Although the impact on reducing heavy metals is uncertain, recycling of collected dusts is a good general practice. Special attention should be paid to the emissions of particulate matter from the lance hole. This hole should be covered during oxygen blowing and, if necessary, inert gas injected into the lance hole to dissipate the particulate matter.

c) Secondary de-dusting, applying:- Efficient capture and exhaust during charging and tapping with subsequent purification

by means of fabric filtration or ESP or any other technique with the same removal effi-ciency. Capture efficiency of about 90% can be achieved. Residual dust content of 5-15 mg/Nm³ in case of bag filters and of 20-30 mg/Nm3 in case of ESP can be achieved.

- Efficient evacuation during hot metal handling (reladling operations), deslagging of hot metal and secondary metallurgy with subsequent purification by means of fabric filtra-tion or any other technique with the same removal efficiency. For these operations emission factors below 5 g/t LS (liquid steel) are achievable.

- Fume suppression with inert gas during reladling of hot metal from torpedo ladle (or hot metal mixer) to charging ladle in order to minimise fume/dust generation.

57. It is recommended that an environmental performance indicator for TPM for the BOF steel-making process would be a maximum of 60 grams per tonne of molten steel for new or modi-fied basic oxygen furnaces and ancillary equipment and a maximum of 90 grams per tonne of molten steel for existing basic oxygen furnaces

Emerging techniques

Sinter plants and blast furnaces

58. New ironmaking techniques discussed below may in future strongly reduce the need for sinter plants.

59. Although the blast furnace route is the main process for iron production, several other pro-duction routes for pig iron are currently being developed and one technique is already applied commercially (Corex). These so-called "smelting reduction" techniques invariably use coal in-stead of coke as the main fuel. Some of the new techniques also replace pellets and sinter by pulverised iron ore. Two main types of alternative ironmaking which can be considered as proven types of alternative ironmaking are following:a) Direct reduction (DR) involves the production of solid primary iron from iron ores and a re-

ducing agent (e.g. natural gas). The solid product is called Direct Reduced Iron (DRI) and is mainly applied as feedstock in electric arc furnaces (EAF) producing steel. The direct re-duction process has been commercialised since the 1970's and a variety of processes have been developed. The DR/EAF technology combination is a complete replacement of the traditional iron sintering/coke oven/BF/BOF steelmaking route.

32

b) Smelting reduction (SR) involves combining iron ore reduction with smelting (cf. blast fur-nace) in a reactor, without the use of coke. The product is liquid pig iron, which can be treated and refined in the same way as pig iron from the blast furnace. Today, only one variant of SR is commercially proven (Corex), but a number of variants are in an advanced state of development.

These processes are alternatives to the coke oven/blast furnace route and possibly with other direct iron smelting processes will replace blast furnaces as they become non-economic. How-ever, no information is available with regard to emissions of heavy metals.

60. Next to the developments in ironmaking, there is a tendency towards continuous processes instead of batch processes. The shift from ingot casting to continuous casting in the 1980's is a representative example of this. In future, batch steelmaking (e.g. Linz-Donawitz -converter, EAF) will probably be replaced by continuous steelmaking processes. However, no information is available with regard to emissions of heavy metals.

Basic oxygen steelmaking and casting

61. The use of new reagents in the desulphurisation process might lead to a decrease in partic-ulate matter emissions and a different (more useful) composition of the generated dusts. The technique is under development.

62. Several foaming techniques at pig iron pre-treatment and steel refining are already avail-able, absorbing the particulate matter arising from the hot metal processing.


63. The Protocol on Heavy Metals includes an emission limit value (ELV) for particulate emis-sions of 50 mg/m³ for sinter plants and for BFs, and of 25 mg/m³ for pellet plants for grinding and drying and for pelletizing or alternatively of 40 g/Mg of pellets produced. For BOF as well as for the heavy metals covered by the Protocol no ELVs are specified.

64. The following table gives an overview on current ELVs implemented by the Parties. Infor-mation was compiled using Parties’ responses to question 44 of the 2004 questionnaire on Strategies and Policies for Compliance Review and additional information by national experts. For comparison, the table also includes BAT associated emission levels as indicated in the Eu-ropean BREF document. All values are expressed in mg/Nm³ referring to standard conditions (273.15 K, 101.3 kPa, dry gas) and do not cover start-up and shutdown periods except stated otherwise.

33

Table 5: ELVs for primary iron and steel production (in mg/Nm³ unless stated otherwise)


ence

ELV Remarks


Protocol (Annex V)

502550

sinter plantspellet plant: grinding, drying, pelletizing; alternatively 40 g/Mg pelletsblast furnacescontinuous (daily) and discontinuous measurements (hourly average)

Austria2 50

20

sinter plants, melting and casting of pig iron, converter, vacuum, electro slag remeltingproduction iron and steelcontinuous (daily) and discontinuous measurements (half-hour aver-age)gaseous or liquid fuels 3%O2 (heat furnace 5%O2), solid fuels 6% O2

Belgium 15050

all installations if mass flow ≤ 500 g/hall installations if mass flow > 500 g/hdiscontinuous or continuous (daily average) measurements

Bulgaria 1050

Blast furnaces: furnace chargingSintering of metallurgic ores, blast furnaces

Czech Republic

501030

10025/50

10050

steel industry and coke-making gas; existing installationsblast furnace; new installationsproduction of steel used elsewhere; new installationsagglomerization, pelletization; existing installationsagglomerization, pelletization; new installationsiron production; existing installationsiron production; new installations

Germany 2010

all installations except blast furnaces (general requirement)blast furnaces (3% O2)continuous (daily) and discontinuous measurements (half-hour aver-age)

Netherlands 40-755-50

Roasting / sintering installations; production of pig iron and steel;8 hour average

Slovakia 50



2331

Sinter plants: new installationsSinter plants: existing installations

2 the regulation is currently under revision, with the aim to reach an adjustment to the state of the art

34

6.823

23 to 68

Blast Furnaces: new installationsBlast Furnaces: existing installationsBasic Oxygen Furnaces (BOFs): ELVs are in this range for various op-erations at BOFs at new and existing installations.

BAT accord-ing to BREF document

<5010-20

<10<10

1-1520-30

5-1520-30

5-15

sinter plantsinter plant using fabric filterpelletisation plantblast furnaces: blast furnace gasblast furnaces: cast house dedustinghot metal pre-treatment (including hot metal transfer processes, desul-phurisation and deslagging) using ESPhot metal pre-treatment using bag filterbasic oxygen furnace using ESPbasic oxygen furnace using bag filteradditionally: hot metal handling (reladling operations), deslagging of hot metal and secondary metallurgy < 5 g/t liquid steel


Austria 0.2 production iron and steel; common ELV for Cd, Hg, Tl; discontinuous measurements (half-hour average)

Belgium 0.2 all installations if mass flow ≥ 1 g/h; common ELV for Cd, Hg, Th and their compounds; discontinuous measurements.

France 0.05 basic oxygen furnace, sinter plants; if mass flow Cd+Hg+Tl > 1 g/h; ad-ditional common ELV of 0.1 mg/Nm³

Germany 0.05 all installations (general requirement); alternatively < 0.15 g/hcommon ELV for Cd and As and their compounds, Benzo(a)pyren, wa-ter soluble Co compounds, Cr(VI) compounds; continuous (daily) and discontinuous measurements (half-hour average)



Austria 5 production iron and steel; common ELV for Pb, Cr (exc. CrVI), Cu, Mn, V, Sn; discontinuous measurements (half-hour average)

Belgium 5 all installations if mass flow ≥ 25 g/h; common ELV for Sb, Pb, Cr, Co, Cu, Mn, Pt, V, Sn and their compounds; discontinuous measurements.

Denmark 1 all installations if mass flow > 5 g/h; hourly average

France 1 basic oxygen furnace, sinter plants; if mass flow Pb and its compounds > 10 g/h

Germany 0.51

all installations except sinter plants (general requirement);sinter plants: sintering beltcommon ELV for Pb, Co, Ni, Se, Te and their compounds; continuous (daily) and discontinuous measurements (half-hour average)



35

Austria 0.2 production iron and steel; common ELV for Cd, Hg, Tl; discontinuous measurements (half-hour average)

Belgium 0.2 all installations if mass flow ≥ 1 g/h; common ELV for Cd, Hg, Th and their compounds. Discontinuous measurements.

Denmark 0.1 all installations if mass flow > 1 g/h; hourly average

France 0.05 basic oxygen furnace, sinter plants; if mass flow Cd+Hg+Tl > 1 g/h; ad-ditional common ELV of 0.1 mg/Nm³

Germany 0.05 all installations (general requirement); alternatively < 0.25 g/hcontinuous (daily) and discontinuous measurements (half-hour aver-age)


References

EC 2001Economic Evaluation of Air Quality Targets for Heavy Metals. European Commission, Entec UK Limited, January 2001.

EIPPCB 2001Integrated Pollution Prevention and Control: Best Available Techniques Reference Document on the Production of Iron and Steel. European IPPC Bureau, Sevilla: December 2001.

U.S. EPA 2000Great Lakes Binational Toxics Strategy: Draft Report for Mercury Reduction Options. United States Environment Protection Agency, September 2000.

U.S. EPA, 2003National Emissions Standard for Hazardous Air Pollutants (NESHAP) for Integrated Iron and Steel Industry. United States Environment Protection Agency, May 20, 2003.

Lemmon 2004Further Development of Emission Standards for the Iron and Steel Sector. William Lemmon and Associates Ltd., Cheminfo Services Inc. (Report prepared for: Environment Canada). Draft, November 2004

36

SECONDARY IRON AND STEEL INDUSTRY

Background

65. This category covers the secondary production of iron and steel (secondary fusion), includ-ing electric arc furnaces (EAF), with a capacity exceeding 2.5 tonnes per hour, for which BATs are considered according to annex III. The production of pig-iron or steel is considered within the primary iron and steel industry.3

66. According to the description of best available techniques (BAT) in annex III of the Protocol, the efficient collection of all emissions by installing doghouses or movable hoods or by total building evacuation is important. For all dust-emitting processes in the secondary iron and steel industry, dedusting in fabric filters, which reduces the dust content to less than 20 mg/m3, shall be considered as BAT. When BAT is used also for minimizing fugitive emissions, the specific dust emission (including fugitive emission directly related to the process) will not exceed the range of 0.1 to 0.35 kg/Mg steel. There are many examples of clean gas dust content below 10 mg/m3 when fabric filters are used. The specific dust emission in such cases is normally below 0.1 kg/Mg.


67. Processing of secondary raw materials such as iron and steel can be a significant source of particulate matter and heavy metals emissions, including mercury emissions, and emission control technologies are often applied to limit these emissions. In this case the origin of the mercury may be from both natural impurities as well as from the intentional use of iron/steel scrap containing mercury (e.g. switches, air-bag activators).

68. Pollution prevention techniques are very effective at reducing mercury emissions from sec-ondary steel production processes. For example, mercury-bearing components in steel scrap can be removed prior to shipping the scrap to a secondary iron & steel facility. The mercury can then be recovered at a mercury recycling facility. Removal of mercury switches from end-of-life automobiles is mandated in all European Union countries. Also, there may be opportunit-ies to remove additional mercury-bearing components from other products prior to recycling in secondary iron & steel facilities.

69. For electric arc furnace steelmaking, the following techniques or combination of techniques are considered as BAT with regard to heavy metals and dust emissions for both new and exist-ing installations:a) Dust collection efficiency:

- With a combination of direct off gas extraction and hood systems or- dog-house and hood systems or- total building evacuation98% and more collection efficiency of primary and secondary emissions from EAF are achievable.

b) Waste gas de-dusting by application of:


37

- Well-designed fabric filter achieving less than 5 mg dust/Nm3 for new plants and less than 15 mg dust/Nm3 for existing plants, both determined as daily mean values.

The minimisation of the dust content correlates with the minimisation of heavy metal emis-sions except for heavy metals present in the gas phase like mercury.

70. It is recommended that the following pollution prevention techniques be included as a best environmental practice: a) Develop and implement operating practices to prevent or minimize the contaminants in the

steel scrap or other raw materials;b) Develop and implement operating practices to prevent or minimize the presence of mercury

in the scrapc) Enclose the filter dust collection and discharge and carry out transfer and disposal in an en-

vironmentally sound method.

71. It is recommended that an environmental performance indicator for the EAF steelmaking process would be a maximum of 60 grams per tonne of molten steel for new or modified elec-tric arc furnaces and a maximum of 120 grams per tonne of molten steel for existing electric arc furnaces.

Emerging techniques

72. In recent years a number of new furnace types have been introduced, that might be re-alised at industrial scale, and that show advantages with regard to heavy metals and dust emissions:- Comelt EAF: integrated shaft scrap preheating and a complete off gas collection in each

operating phase.- Contiarc furnace: waste gas and dust volumes are considerably reduced, and the gas-tight

furnace enclosure captures all primary and nearly all secondary emissions.- Direct reduction (DR) involves the production of solid primary iron from iron ores and a re-

ducing agent (e.g. natural gas). The solid product is called Direct Reduced Iron (DRI) and is mainly applied as feedstock in electric arc furnaces (EAF). The direct reduction process has been commercialised since the 1970's and a variety of processes have been developed. The use of DRI in EAF steelmaking is forecast to continue to grow in the near future. The major driving forces for DRI production are the need for virgin material in the EAF steelmak-ing process to produce higher quality steel and the increasing price of steel scrap offset by increased natural gas prices.

- The use of liquid iron might be a further option.


73. The Protocol on Heavy Metals includes an emission limit value (ELV) for particulate emis-sions of 20 mg/m³ for EAF. For other related processes and for the heavy metals covered by the Protocol no ELVs are specified.

74. The following table gives an overview on current ELVs implemented by the Parties. Infor-mation was compiled using Parties’ responses to question 44 of the 2004 questionnaire on Strategies and Policies for Compliance Review and additional information by national experts. For comparison, the table also includes BAT associated emission levels as indicated in the Eu-ropean BAT reference (BREF) document. All values are expressed in mg/Nm³ referring to standard conditions (273.15 K, 101.3 kPa, dry gas) and do not cover start-up and shutdown pe-riods except stated otherwise.

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Table 6: ELVs for secondary steel production (in mg/Nm³ unless stated otherwise)

Country ELV Remarks


Protocol (Annex V)

20 EAF > 2.5 t/h; continuous (daily) and discontinuous measurements (hourly average)

Austria4 2050

EAF, induction, ladle furnaceconverter, vacuum melting, electro slag remeltingcontinuous (daily) and discontinuous measurements (half-hour aver-age), gaseous or liquid fuels 3%O2 (heat furnace 5%O2), solid fuels 6% O2

Belgium 20 EAF; discontinuous or continuous (daily average) measurements

Bulgaria 20 EAF

Czech Republic

5020

EAF < 2.5 t/h, new installationsEAF > 2.5 t/h, new installations

Germany 520

EAFall installations (general requirement)continuous (daily) and discontinuous measurements (half-hour aver-age)

Slovakia 50



12 EAF: ELV for new installations, based on regulation finalized in 1984 and applies to facilities built after 1984 (U.S. EPA, 1984).


< 15< 5

EAF, existing installations, daily meanEAF, new installations, daily mean


Austria 0.2 production of iron and steel; common ELV for Cd, Hg, Th; discontinu-ous measurements (half-hour average)


France 0.05 EAF if mass flow Cd+Hg+Tl > 1 g/h; additional common ELV of 0.1 mg/Nm³




4 the regulation is currently under revision, with the aim to reach an adjustment to the state of the art

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Austria 5 production of iron and steel; common ELV for Pb, Cr (exc. CrVI), Cu, Mn, V, Sn; discontinuous measurements (half-hour average)

Belgium 5 all installations if mass flow ≥ 25 g/h; common ELV for Sb, Pb, Cr, Co, Cu, Mn, Pt, V, Sn and their compounds. Discontinuous measurements.


France 1 EAF if mass flow Pb and its compounds > 10 g/h

Germany 0.5 all installations (general requirement); common ELV for Pb, Co, Ni, Se, Te and their compounds; continuous (daily) and discontinuous measurements (half-hour average)



Austria 0.2 production iron and steel; common ELV for Cd, Hg, Th; discontinuous measurements (half-hour average)



France 0.05 EAF if mass flow Cd+Hg+Tl > 1 g/h; additional common ELV of 0.1 mg/Nm³



References

EIPPCB 2001Integrated Pollution Prevention and Control: Best Available Techniques Reference Document on the Production of Iron and Steel. European IPPC Bureau, Sevilla: December 2001.

UNEP 2002Global Mercury Assessment. United Nations Environmental Programme. UNEP Chemicals, December 2002.

U.S. EPA, 1984. New Source Performance Standard (NSPS) for Secondary Iron and Steel (Electric Arc Furnaces). 40 Code of Federal Regulations (CFR) Part 60, Subpart AAa. Octo-ber 31, 1984.

Lemmon 2004Further Development of Emission Standards for the Iron and Steel Sector. William Lemmon and Associates Ltd., Cheminfo Services Inc. (Report prepared for: Environment Canada). Draft, November 2004

40

Lourie & Love 2002Mercury Use in Switches in Canada and Estimating the Release of Mercury from these Sources at Electric Arc Furnaces, prepared for CCME by Lourie & Love Inc., March 2002

41

IRON FOUNDRIES

Background

75. This sector covers ferrous metal foundries with a capacity exceeding 20 tonnes per day. According to annex III of the Protocol, best available techniques (BAT) are considered for cupola and induction furnaces that are operated in iron foundries. Electric Arc Furnaces (EAFs) are treated within the secondary iron and steel industry.

76. Rotary furnaces are not currently taken into account in Annex III but may be a relevant source of heavy metal emissions. Therefore, additional information is given for these installa-tions.

77. According to Annex III, the efficient collection of all emissions by installing doghouses or movable hoods or by total building evacuation is important. Emission reduction with electro-static precipitators (ESPs), fabric filters (FFs), the latter also combined with pre-dedusting, dry absorption or chemisorption, or venturi scrubbers can reduce dust concentrations to 20 mg/m3, or less. For existing smaller installations, these measures may not be BAT if they are not eco-nomically viable.


78. For the foundries industry, emissions to air are the key environmental concern. The foundry process generates (metal-laden) mineral dusts, acidifying compounds, products of incomplete combustion and volatile organic compounds. Dust is a major issue, since it is generated in all process steps, in varying types and compositions. Dust is emitted from metal melting, sand moulding, casting and finishing. Any dust generated may contain metal and metal oxides. In the foundry process, emissions to air will typically not be limited to one (or several) fixed point(s). The process involves various emission sources (e.g. from hot castings, sand, hot metal). A key issue in emission reduction is not only to treat the exhaust and off-gas flow, but also to capture it.

79. For iron foundries, the following techniques or combination of techniques (Points 75 through 84) are considered as BAT (according to the BREF) with regard to heavy metals and dust emissions. The BAT associated emission level for dust, after collecting and dedusting ex-haust gases, for all types of furnaces (cupola, induction, and rotary furnace) and mouldings (lost mould and permanent mould) as well as finishing operations is 5-20 mg/m³ (daily average, standard conditions).

Fugitive emissions

80. BAT is to minimise fugitive emissions arising from various non-contained sources in the process chain, by using a combination of the following measures. The emissions mainly involve losses from transfer and storage operations and spills.- avoid outdoor or uncovered stockpiles, but where outdoor stockpiles are unavoidable, to

use sprays, binders, stockpile management techniques, windbreaks, etc.- cover skip and vessels

43

- vacuum clean the moulding and casting shop in sand moulding foundries - clean wheels and roads- keep outside doors shut- carry out regular housekeeping

81. Additionally, fugitive emissions may arise from the incomplete evacuation of exhaust gas from contained sources, e.g. emissions from furnaces during opening or tapping. BAT is to minimise these fugitive emissions by optimising capture and cleaning. For this optimisation one or more of the following measures are used, giving preference to the collection of fume nearest to the source:- hooding and ducting design to capture fume arising from hot metal, furnace charging, slag

transfer and tapping- applying furnace enclosures to prevent the release of fume losses into the atmosphere- applying roofline collection, although this is very energy consuming and should only be ap-

plied as a last resort.

Cupola furnace melting of cast iron

82. The amount of dust and exhaust gases resulting are directly related to the amount of coke charged per tonne of iron. Therefore, all measures that improve the thermal efficiency of the cupola will also reduce the emissions from the furnace. For the operation of cupola furnaces, BAT is all of the following, to:a) use divided blast operation (2 rows of tuyères) for cold blast cupolasb) use oxygen enrichment of the blast air, in a continuous or intermittent way, with oxygen lev-

els between 22 and 25 % (i.e. 1 % - 4 % enrichment)c) minimise the blast-off periods for hot blast cupolas by applying continuous blowing or long

campaign operation. Depending on the requirements of the moulding and casting line, du-plex operations must be considered- apply good melting practice measures for the furnace operation- Operating the furnace in its optimum regime as much as possible- Avoiding excess temperatures- Uniform charging:- Minimising air losses- Avoiding “bridging” in the cupola- Utilising good lining practice

d) use coke with known properties and of a controlled qualitye) clean furnace off-gas by subsequent collection, cooling and dedusting. BAT for dedusting is

to use a bag filter or wet scrubber.

Induction furnace melting of cast iron and steel

83. For the operation of induction furnaces, BAT is all of the following, to:- apply measures to increase furnace efficiency through shorter melting times and reduced

downtime.- use a hood, lip extraction or cover extraction on each induction furnace to capture the fur-

nace off-gas and to maximise off-gas collection during the full working cycle- use dry flue-gas cleaning- keep dust emissions below 0.2 kg/tonne molten iron.

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Rotary furnace melting of cast iron

84. For the operation of rotary furnaces, BAT is all of the following, to:- use techniques to optimise furnace operation and to increase the melting efficiency.- collect the off-gas close to the furnace exit, apply post combustion, cool it using a heatex-

changer and then to apply dry dedusting.

Lost mould casting

85. For green sand moulding, BAT for green sand preparation is to enclose all the unit opera-tions of the sand plant (vibrating screen, sand dedusting, cooling, mixing operations) and to de-dust the exhaust gas.

86. For chemically-bonded sand mould and core-making, all types of binders are determined as BAT if they are applied according to good practice measures, which mainly involve process control and exhaust capture measures to minimise emissions.

87. Pouring, cooling and shake-out generate emissions of dust, volatile organic compounds (VOCs) and other organic products. BAT is to:- enclose pouring and cooling lines and to provide exhaust extraction, for serial pouring lines,

and- enclose the shake-out equipment, and to treat the exhaust gas using wet or dry dedusting.

Permanent mould casting

88. BAT for sand preparation in permanent mould casting is to enclose all the unit operations of the sand plant (vibrating screen, sand dedusting, cooling, mixing operations) and to dedust the exhaust gas.

89. BAT for used sand management in permanent mould foundries is to enclose the de-coring unit, and to treat the exhaust gas using wet or dry dedusting.

Finishing of castings

90. For abrasive cutting, shot blasting and fettling, BAT is to collect and treat the finishing off-gas using a wet or dry system. If an Argon-Oxygen Decarborization (AOD) converter is used for steel refining, BAT is to extract and collect the exhaust gas using a roof canopy.

Emerging techniques

91. Use of low cost combustible materials in cupola melting: In order to reduce the consump-tion of coke, techniques have been developed to allow the use of high calorific value solid waste (tyres, plastic pieces, etc.) together with lower grade coke as a fuel. However, the appli-cation of alternative fuels will cause a change in the flue-gas composition; leading to higher amounts of dust for disposal, possibly with a higher content of pollutants and an increased risk of dioxins, PAHs and heavy metals.

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92. The Protocol on Heavy Metals does not specify any ELV for this category.


Table 7: ELVs for iron foundries (in mg/Nm³ unless stated otherwise)

Country ELV Remarks


Austria 20

50

Induction, EAF, cupola with furnace top extraction; heat treatment; core prod. ≥0.5 kg/h other furnaces; plants of sand regeneration, mould production, cleaning and fettling (>25 kg/h)5% O2 for heat treatment furnaces; continuous (daily) or discontinuous measurements (half-hour average)

Belgium 20 foundriesdiscontinuous or continuous (daily average) measurements

Germany 20 all installations (general requirement)continuous (daily) and discontinuous measurements (half-hour aver-age)

Netherlands 5 daily average or half hourly average for discontinuous measurements



4.613.8 2.3

11.5

4.623

Cupola or electric arc furnace: new installationsCupola furnace: existing installationsElectric induction furnace or scrap pre-heater: new installationsElectric arc furnace, electric induction furnace or scrap pre-heater: ex-isting installationsPouring area or pouring station: new installationsPouring area or pouring station: existing installations


5-20 daily average; additionally dust emissions < 0.2 kg/tonne molten iron for induction furnaces


Austria 0.2 common ELV for Cd, Tl; 5% O2 for heat treatment furnaces; discontinu-ous measurements (half-hour average)


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France 0.05 foundries; if mass flow Cd+Hg+Tl > 1 g/h; additional common ELV of 0.1 mg/Nm³


Netherlands 0.05 If mass flow of Cd is > 0.25 mg/m3

Slovakia 50



Austria 5 common ELV for Pb, Zn, Cr, Cu, V, Sn; 5% O2 for heat treatment fur-naces; discontinuous measurements (half-hour average)



France 1 foundries; if mass flow Pb and its compounds > 10 g/h

Germany 0.5 all installations (general requirement); common ELV for Pb, Co, Ni, Se, Te and their compounds; continuous (daily) and discontinuous measurements (half-hour average)

Netherlands 0.5 If mass flow of Pb is > 2.5 mg/m3



Austria 0.1 common ELV for Hg, Be; 5% O2 for heat treatment furnaces; discon-tinuous measurements (half-hour average)



France 0.05 foundries; if mass flow Cd+Hg+Tl > 1 g/h; additional common ELV of 0.1 mg/Nm³


Netherlands 0.05 If mass flow of Hg is > 0.25 mg/m3


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References

EIPPCB 2005Integrated Pollution Prevention and Control: Reference Document on Best Available Tech-niques in the Smitheries and Foundries Industry. European IPPC Bureau, Sevilla: May 2005.

U.S. EPA, 2004. National Emission Standards for Hazardous Air Pollutants for Iron and Steel Foundries: Final Rule, 69 Federal Register 21905. United States Environmental Protection Agency. 22 April 2004.

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PRIMARY AND SECONDARY NON-FERROUS METAL INDUSTRY

Background

94. This category covers the primary and secondary production of non-ferrous metals. With re-spect to the heavy metals of concern, according to Annex II consideration is limited to the pro-duction of copper, lead, zinc and mercury. For the production from ore, concentrates or sec-ondary raw materials of copper, lead, and zinc by metallurgical processes, the coverage is lim-ited to installations with a capacity exceeding 30 tonnes of metal per day for primary installa-tions and 15 tonnes of metal per day for secondary installations. For installations for the smelt-ing, including alloying, of these metals, including recovered products, the coverage is restricted to installations with a melting capacity of more than 4 tonnes per day for lead and 20 tonnes per day for copper and zinc. According to annex III, BAT are also considered for the primary production of gold.5

95. Secondary aluminium production is not currently taken into account but may be a relevant source of heavy metal emissions. Therefore, additional information is given for these sector.

96. Large amounts of mercury are currently brought out of use as a result of ongoing and antic-ipated substitution of mercury-based chlor-alkali production in Europe and North America. Use of mercury is declining, at both global and EU levels, yet some significant uses remain. The main global uses are gold mining, batteries and the chlor-alkali industry, together accounting for over 75% of consumption. As a pro-active contribution to a proposed globally organised ef-fort to phase out primary production of mercury and to stop surpluses re-entering the market, the European Commission intends to propose an amendment to Regulation (EC) No. 304/2003 to phase out the export of mercury from the European Community by 2011. In North America, to reduce supply, the US Government decided in 2004 to place a large quantity of previously stockpiled mercury into long-term storage (at least 40 years) to prevent it from entering the market (U.S. DNSC, 2004).

97. According to annex III, BAT in this sector are the following:a) For mercury production, soot from the condensers and settling tanks should be removed,

treated with lime and returned to the retort or furnace. For efficient recovery of mercury the following techniques can be used:- Measures to reduce dust generation during mining and stockpiling, including minimizing

the size of stockpiles;- Indirect heating of the furnace;- Keeping the ore as dry as possible;- Bringing the gas temperature entering the condenser to only 10 to 20°C above the dew

point;- Keeping the outlet temperature as low as possible; and- Passing reaction gases through a post-condensation scrubber and/or a selenium filter.Dust formation can be kept down by indirect heating, separate processing of fine grain classes of ore, and control of ore water content. Dust should be removed from the hot reac-tion gas before it enters the mercury condensation unit with cyclones and/or ESPs.


49

b) For gold production by amalgamation, similar strategies as for mercury can be applied. Gold is also produced using techniques other than amalgamation, and these are consid-ered to be the preferred option for new plants.

c) For the production of non-ferrous metals from sulfitic ores, fabric filters should be used when appropriate. A dust content of less than 10 mg/m3 can be obtained. The dust should be recycled in-plant or off-site. Before being fed to an SO3 contact plant, the off-gas must go through a thorough dedusting (< 3 mg/m3) and could also require additional mercury re-moval thereby also minimizing heavy metal emissions.

d) For primary lead production, first experiences indicate that there are interesting new direct smelting reduction technologies without sintering of the concentrates. These processes are examples of a new generation of direct autogenous lead smelting technologies which pol-lute less and consume less energy.

e) Secondary lead is mainly produced from used car and truck batteries,. This BAT should in-clude one melting operation in a short rotary furnace or shaft furnace. Oxy-fuel burners can reduce waste gas volume and flue dust production by 60%. Cleaning the flue-gas with fab-ric filters makes it possible to achieve dust concentration levels of 5 mg/m3.

f) For primary zinc production, pressure leaching may be an alternative to roasting and may be considered as a BAT for new plants depending on the concentrate characteristics. Emis-sions from pyrometallurgical zinc production in Imperial Smelting (IS) furnaces can be mini-mized by using a double bell furnace top and cleaning with highefficiency scrubbers, effi-cient evacuation and cleaning of gases from slag and lead casting, and thorough cleaning (< 10 mg/m3) of the CO-rich furnace off-gases.

g) In general , processes should be combined with an effective dust collecting device for both primary gases and fugitive emissions. Dust concentrations below 5 mg/m3 have been achieved in some cases using fabric filters.


98. The main environmental issues for the production of most non-ferrous metals from primary raw materials include the potential emission to air of dust and metals/metal compounds. The pyrometallurgical processes are potential sources of dust and metals from furnaces, reactors and the transfer of molten metal. The production from secondary raw materials is also related to the off-gases from the various furnaces and transfers that contain dust and metals.

99. In the majority of cases these process gases are cleaned in fabric filters and so the emis-sions of dust and metal compounds such as lead are reduced. Gas cleaning using wet scrub-bers and wet electrostatic precipitators is particularly effective for process gases that undergo sulfur recovery in a sulfuric acid plant. In some cases where dust is abrasive or difficult to filter, wet scrubbers are also effective. The use of furnace sealing and enclosed transfers and stor-age is important in preventing fugitive emissions.

Materials handling and storage

100. The techniques that are used depend to a large extent on the type of material that is be-ing used. BAT to prevent releases of particulate matter and heavy metals from raw material handling are:- Transfer conveyors and pipelines placed in safe, open areas above ground so that leaks

can be detected quickly and damage from vehicles and other equipment can be prevented.- Where required, sealed delivery, storage and reclamation systems can be used for dusty

materials and silos can be used for day storage. Completely closed buildings can be used for the storage of dusty materials and may not require special filter devices.

50

- Sealing agents (such as molasses and PVA) can be used where appropriate and compati-ble to reduce the tendency for material to form dust.

- Where required enclosed conveyors with well designed, robust extraction and filtration equipment can be used on delivery points, silos, pneumatic transfer systems and conveyor transfer points to prevent the emission of dust.

- Rationalised transport systems can be used to minimise the generation and transport of dust within a site.

Fume and gas collection

101. Emissions to air arise from the storage, handling, pre-treatment, pyro-metallurgical and hydrometallurgical stages. Transfer of materials is particularly important. Data provided has confirmed that the significance of fugitive emissions in many processes is very high and that fugitive emissions can be much greater than those that are captured and abated. In these cases it is possible to reduce environmental impact by following the hierarchy of gas collection techniques from material storage and handling, reactors or furnaces and from material transfer points. Potential fugitive emissions must be considered at all stages of process design and de-velopment. The hierarchy of gas collection from all of the process stages is:- Process optimisation and minimisation of emissions;- Sealed reactors and furnaces;- Targeted fume collection;

102. With regard to dust and heavy metals emissions, important gas collection measures are:- The use of sealed furnaces or other process units to prevent fugitive emissions, allow heat

recovery and the collection of process gases.- The use of semi-sealed furnaces where sealed furnaces are not available.- The minimisation of material transfers between processes.- Where such transfers are unavoidable, the use of launders in preference to ladles for

molten materials.- In some cases the restriction of techniques to those that avoid molten material transfers

may prevent the recovery of some secondary materials that would then enter the waste stream. In these cases the use of secondary or tertiary fume collection is appropriate so that these materials can be recovered.

- Hooding and ductwork design to capture fume arising from hot metal, matte or slag trans-fers and tapping.

- Furnace or reactor enclosures may be required to prevent release of fume losses into the atmosphere.

- Where primary extraction and enclosure are likely to be ineffective, then the furnace can be fully closed and ventilation air drawn off by extraction fans to a suitable treatment and dis-charge system.

- Roofline collection of fume is very energy consuming and should be a last resort.

Removal of mercury

103. Mercury removal is necessary when using raw materials that contain the metal. Mercury appears as an impurity of copper, zinc, lead, and nickel ores. The element is also present in the gold ores. The following techniques are considered to be BAT.- The Boliden/Norzink process with the recovery of the scrubbing solution and production of

mercury metal.- Bolchem process with the filtering off the mercury sulphide to allow the acid to be returned

to the absorption stage.- Outokumpu process: Mercury is removed as sulphide from the gas stream.

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- Sodium thiocyanate process.- Activated Carbon Filter. An adsorption filter using activated carbon is used to remove mer-

cury vapour from the gas stream as well as dioxins.

104. For processes where mercury removal from the gases is not practicable the two pro-cesses to reduce the mercury content in sulphuric acid produced during the production of non-ferrous metals are considered to be BAT.- Superlig Ion Exchange process.- Potassium iodide process.The emissions associated with the above processes are related to any residual mercury that will be present in the acid that is produced, the product specification is normally < 0.1 ppm (mg/l) and is equivalent to ~ 0.02 mg/Nm3 in the cleaned gas.

105. Formation of particles of chloride and sulfate salts was considered to be an important re-moval mechanism for mercury in the FGD process. This would be promoted by high Cl content in the coal and for mercury sulfate, and by low temperatures combined with the catalytic effect of activated carbon.- The relatively low temperatures found in wet scrubber systems allow many of the more

volatile trace elements to condense from the vapor phase and thus to be removed from the flue gases. In general, removal efficiency for mercury ranges from 30 to 50%.

- In summary, the overall removal of mercury in various spray dry systems varies from about 35 to 85%. The highest removal efficiencies are achieved from spray dry systems fitted with downstream fabric filters.

106. Mercury releases and health hazards from artisanal gold mining activities may be re-duced by educating the miners and their families about hazards, by promoting certain tech-niques that are safer and that use less or no mercury and, where feasible, by putting in place facilities where the miners can take concentrated ores for the final refining process.

Abatement of dust and heavy metals emissions

107. BAT for the abatement of dust and heavy metals emissions are the following:- Fume collection systems used should exploit furnace or reactor sealing systems and be de-

signed to maintain a reduced pressure that avoids leaks and fugitive emissions, where ap-plicable. Systems that maintain furnace sealing or hood deployment should be used. Exam-ples are through electrode additions of material, additions via tuyeres or lances and the use of robust rotary valves on feed systems. The use of an intelligent system capable of target-ing the fume extraction to the source and duration of any fume is more energy efficient.

- Overall for dust and associated metal removal, fabric filters (after heat recovery or gas cool-ing) can provide the best performance provided that modern wear resistant fabrics are used, the particles are suitable and continuous monitoring is used to detect failure. Modern filter (e.g. membrane filter) offer significant improvements in performance, reliability and life and therefore offer cost savings in the medium term. They can be used in existing installa-tions and can be fitted during maintenance. They feature bag burst detection systems and on-line cleaning methods.

- For sticky or abrasive dusts, wet electrostatic precipitators or scrubbers can be effective provided that they are properly designed for the application.

- Best Available Techniques for gas and fume treatment systems are those that use cooling and heat recovery if practical before a fabric filter except when carried out as part of the production of sulphuric acid. The gas cleaning stage that is used prior to the sulphuric acid plant will contain a combination of dry ESP, wet scrubbers, mercury removal and wet ESP.

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BAT for gas collection and abatement for the various process stages regarding to PM and heavy metals are summarized in the following table:

Materials handling and stor-age.

Correct storage, handling and transfer. Dust collection and fabric filter if necessary.

Grinding, drying. Process operation. Gas collection and fabric filter.Sintering/roasting, Smelting, Converting, Fire refining

Gas collection, gas cleaning in fabric filter, heat recovery.

Slag treatment. Gas collection, cooling and fabric filter.Thermal refining. Gas collection and fabric filter.Electrode baking, graphitisa-tion

Gas collection, condenser and ESP, afterburner or alumina scrub-ber and fabric filter.

Metal powder production Gas collection and fabric filter.Melting and casting. Gas collection and fabric filter.

108. FFs may not be BAT for the recovery of non-ferrous metals from sulfur-bearing concen-trates due to the potential for condensation of sulphuric acid on the baghouse filter media par-ticularly during temporary outages and operation at gas temperatures below the acid gas dew point. If FFs are correctly designed, constructed and sized, they can be considered as BAT. The ESP may be the preferred PM abatement method for some applications. It will tolerate short periods of condensation without plugging/blinding as occurs immediately even with mod-ern fabric filters (e.g., membrane filter bags).

109. When BAT are used, the associated emission level for dust, depending on its character-istics, for FF and alumina scrubber is 1-5 mg/Nm³, and for wet ESP or ceramic filter < 5 mg/Nm³ (daily average, standard conditions).

110. The concentration of heavy metals is linked to the concentration of dust and proportion of the metals in the dust. The metal content of dust varies widely between processes. In addition, for similar furnaces there are significant variations in metal content due to the use of varying raw materials. It is considered that low concentrations of heavy metals are associated with the use of high performance, modern abatement systems such as a membrane fabric filter pro-vided the operating temperature is correct and the characteristics of the gas and dust are taken into account in the design. A total dust retention of more than 99.75 % can be achieved with the use of ESPs and FFs, the contents of heavy metals, including mercury on particles in the flue gas can be reduced by at least 95.0 to 99.0 %.

Production of copper and its alloys from primary and secondary raw materials

111. Process selection for primary copper smelting : Depending on the raw materials available, BAT are:- The continuous processes from Mitsubishi and Outokumpu/Kennecott are considered to be

BAT for the smelting and converting stage. The Mitsubishi system also treats copper sec-ondary raw material and scrap. The Mitsubishi and Outokumpu processes are derivatives of the Canadian INCO flash furnace which was the first continuous smelting process for copper and nickel. The Mitsubishi and Outokumpu processes are derivatives of the Cana-dian INCO flash furnace which was the first continuous smelting process for copper and nickel.

- Similar environmental performance, using concentrate blends from various sources, can be achieved using the Outokumpu Flash Smelting Furnace, and for smaller throughputs the

53

ISA Smelt furnace. These furnaces are used in combination with the Peirce-Smith (or simi-lar) converter.

- The combination of partial roasting in a fluid bed roaster, electric furnace matte smelting and Peirce-Smith converter offers advantages for the treatment of complex feed materials allowing recovery of other metals contained in the concentrate like zinc and lead.

- The use of the Outokumpu Flash Smelting Furnace for direct smelting to blister copper us-ing specific concentrates with a low iron content or very high grade concentrates (low slag fall).

- The Noranda, El Teniente converter and Contop furnaces may also achieve the same envi-ronmental performance as those listed above, given good gas collection and abatement systems. The INCO flash furnace may also have advantages but operates with 100% oxy-gen resulting in a narrow operating window.

Gases from the primary smelting and converting processes should be treated to remove dust and volatile metals.

112. Process selection for the production of copper from secondary raw materials: For the pro-duction of copper from secondary raw materials the variation in feed stock and the control of quality also has to be taken into account at a local level and this will influence the combination of furnaces, pre-treatment and the associated collection and abatement systems that are used. BAT are Blast Furnaces, mini-smelter, TBRC, Sealed Submerged Arc Electric furnace, ISA Smelt, and the Peirce-Smith converter. The submerged arc electric furnace is a sealed unit and is therefore inherently cleaner than the others, provided that the gas extraction system is ade-quately designed and sized. The electric furnace is also used for secondary material. For high grades of copper scrap without organic contamination, the reverberatory hearth furnace, the hearth shaft furnace and Contimelt process are considered to be BAT in conjunction with suit-able gas collection and abatement systems.

113. Process selection for primary and secondary converting : If batch operated converters such as the Peirce-Smith converters (or similar) are used they should be used with total enclo-sure or efficient primary and secondary fume collection systems. The hooding systems should be designed to allow access for the ladle transfers while maintaining good fume collection. This can be achieved by the use of a system of intelligent control to target fume emissions automati-cally as they occur during the cycle. The blowing cycle of the converter and the fume collection system should be controlled automatically to prevent blowing while the converter is rolled out. Additions of materials through the hood or tuyeres should be used if possible. The ISA Smelt furnace can be operated batch-wise, where smelting is carried out in a first stage followed by conversion in a second stage, and is also considered as BAT.

114. Process selection for other processes stages : BAT are:- The drying of concentrate etc in directly fired drum and flash dryers, in fluid bed and steam

dryers.- Slag treatment by electric furnace slag cleaning, slag fuming, crushing/grinding and slag

flotation.- Fire refining in rotary or tilting reverberatory furnaces. Anode casting in pre-formed moulds

or in a continuous caster.- Electrolytic copper refining by optimised conventional or mechanised permanent cathode

technology.- The hydro-metallurgical processes using the electro-winning process are considered to be

BAT for oxidic ores and low grade, complex and precious metal free copper sulphide ores.

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115. Gas collection and abatement : Fume production from secondary raw materials can be minimised by the choice of the furnace and abatement systems. Secondary fume collection is needed in the case of some batch converters and for the ventilation of tap-holes, launders etc. BAT for gas collection and abatement for the various process stages with the regard to PM and HM are summarized in the following table:

Raw materials handling. Correct storage, handling and transfer. Dust collection and fabric filter.

Raw materials thermal pre-treatment

Correct pre-treatment. Gas collection and fabric filter.

Primary smelting Process operation and gas collection, gas cleaning followed by gas cooling/final cleaning (normally followed by sulphuric acid plant)

Secondary smelting Process operation and gas collection, cooling and cleaning by fab-ric filter; scrubbing if necessary

Primary converting Process operation and gas collection, gas cleaning (followed by sulphuric acid plant)

Secondary converting Process operation and gas collection, cooling and cleaning by fab-ric filter; scrubbing if necessary

Fire refining Process operation and gas collection, cooling and cleaning by fab-ric filter or scrubber

Melting and casting. Process operation and gas collection, cooling and cleaning by fab-ric filter.

Pyro-metallurgical slag treat-ment

Process operation and gas collection, cooling and cleaning by fab-ric filter.

116. The BAT associated emission level for dust is 1-5 mg/Nm³ (daily average). For secondary smelting and converting, primary and secondary fire refining, electric slag cleaning and melting, it can be reached using high performance fabric filters. For secondary fume collection systems and drying processes, fabric filter with lime injection (for SO2 collection/filter protection) are BAT.

Production of aluminium from secondary raw materials

117. Process selection for secondary aluminium smelting : The smelting and melting processes that are considered to be BAT are the Reverberatory furnace, Tilting rotary furnace, Rotary fur-nace, Meltower Induction furnace, depending on the feed materials, with the following features:- The use of a sealed charging carriage or similar sealed feeding system if possible.- The use of enclosures or hoods for the feeding and tapping areas and targeted fume ex-

traction systems if practical- The use of coreless-induction furnaces for relatively small quantities of clean metal- The use of fabric or ceramic filters for dust removal.

118. Process selection for other processes stages : BAT for Holding or De-gassing is the fume collection from furnaces and launders, cooling, and fabric filter if necessary.

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119. Gas collection and abatement : BAT for gas and fume treatment systems are those that use cooling and heat recovery if practical before a fabric filter. FF or ceramic filters that use modern high performance materials in a well constructed and maintained structure are applica-ble. The use of or the recycling of skimmings and filter dusts, if it is possible, is considered to be part of the processes. BAT for gas collection and abatement for the various process stages are summarized in the following table:

Raw materials handling. Dust prevention and correct storage. Dust collection and fabric fil-ter.

Raw materials pre-treatment Correct pre-treatment. Gas collection and fabric filter.

Secondary smelting Process operation, gas collection and efficient dust removal.

Holding and refining Process operation and gas collection/cleaning

Salt slag and skimmings treat-ment processes

Process operation and gas collection/treatment

120. The BAT associated emission level for dust is 1-5 mg/Nm³ (daily average) for materials pre-treatment (including swarf drying), melting and smelting of secondary aluminium and hold-ing and de-gassing molten metal, using a high performance fabric filter.

Production of lead and zinc from primary and secondary raw materials

121. Process selection for primary lead smelting : Depending on the raw materials available, BAT are:

applied technique raw material

Kaldo process TBRC (Totally enclosed)

Pb concentrate and secondary (most grades)

ISF and New Jersey Distilla-tion

Zn/Pb concentrates

QSL Pb concentrate and secondary material

Kivcet furnace Cu/Pb concentrate and secondary material

Kaldo Furnace Pb concentrate and secondary material

ISA Smelt Furnace Pb concentrate and secondary material

Blast Furnace complex lead bearing primary and secondary material

Gases from the sintering, roasting and direct smelting processes should be treated to remove dust and volatile metals.

122. Process selection for secondary lead smelting : Depending on the raw materials available, processes that are BAT are: The blast furnace (with good process control), ISA Smelt/Ausmelt, the electric furnace and the rotary furnace. The submerged arc electric furnace is used for mixed copper and lead materials. It is a sealed unit and is therefore inherently cleaner than the others, provided that the gas extraction system is adequately designed and sized. The electric furnace is used for secondary material containing sulphur and is connected to a sulphuric acid plant. When only clean lead and clean scrap is used, also melting crucibles and kettles is BAT.

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123. Process selection for lead refining : Processes would be used with efficient primary and if necessary, secondary fume collection systems. Temperature control of the refining kettles is articularly important to prevent lead fume and indirect heating is more effective in achieving this.

124. Process selection for primary and secondary zinc production : No specific process is BAT provided that for any process good process control, gas collection and abatement systems are used.

125. Gas collection and abatement : The ISF process need to use wet scrubbing so that the gases are cooled prior to use as a fuel. BAT for gas collection and abatement for the various process stages are summarized in the following table:

Raw materials handling. Correct storage, dust collection and fabric filter.

Raw materials pre-treatment (mechanical de-coating/strip-ping; thermal de-coating)

Correct pre-treatment. Gas collection and fabric filter.

Primary roasting and smelting, sintering

Process operation, gas collection, gas cleaning, cooling and sul-phuric acid plant

ISF Wet scrubbing (to cool gas) prior to use as LCV (low calorific value) gas

Secondary smelting Process operation and gas collection, cooling and fabric filter

Thermal refining Process operation, gas collection, cooling and fabric filter

Melting, alloying, casting and dust production

Process operation, gas collection, cooling and fabric filter

Slag fuming and Waelz kiln processes

Process operation, gas collection, cooling and fabric filter or wet ESP if wet quenching is used.

126. The BAT associated emission level for dust is 1-5 mg/Nm³ (daily average). This can be achieved using a high performance fabric filter for the melting of clean material, alloying and zinc dust production. Temperature control of melting kettles or vessels is needed to prevent volatilisation of metals. For materials pre-treatment, secondary smelting, thermal refining, melt-ing, slag fuming and Waelz kiln operation, this can be achieved using a high performance fab-ric filter or wet ESP (A wet ESP may be applicable to gases from slag granulation or wet gas quenching).

Production of gold

127. Process selection : No specific process is considered as BAT. The use of the copper route for smelting precious metals has a lower potential for the emission of lead to all environmental media and should be used if the combination of raw materials, equipment and products allows it.

128. In Nevada, USA, as part of the Voluntary Mercury Reduction Program several large gold production facilities reduced their mercury emissions within two to three years (2000-2003) by about 75% by applying various control technologies and pollution prevention measures, includ-

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ing carbon adsorption units, mercurous chloride scrubbers, venture scrubbers, and chemical additives to improve mercury capture (Miller and Jones 2005).

129. Gas collection and abatement : Secondary fume collection is needed in the case of some furnaces. The use of or the recycling of acids, slags, slimes and filter dusts are considered to part of the processes. In the case of high content of mercury in the ore it is necessary to use an activated carbon adsorber bed. BAT for gas collection and abatement for the various process stages are summarized in the following table:

Raw materials handling. Correct storage. Dust collection and fabric filter if necessary.

Raw materials pre-treatment Correct pre-treatment. Gas collection and fabric filter.

Roasting and smelting Process operation, gas collection, cooling and fabric filter; scrub-bing if necessary

Selenium roasting Process operation, gas collection, cooling and dust removal, scrub-bing and wet ESP

Dissolution and chemical refin-ing

Process operation and gas collection with oxidising scrubber

Thermal refining (Miller process)

Process operation, gas collection, scrubbing and wet ESP

Melting, alloying and casting Process operation, gas collection, cooling and fabric filter

Slag treatment and cupelling Process operation, gas collection, cooling and fabric filter.

130. The BAT associated emission level for dust for materials pre-treatment (including inciner-ation), roasting, cupelling, smelting, thermal refining, and melting for precious metal recovery is 1-5 mg/Nm³ (daily average). This can be achieved using a high performance fabric filter or ce-ramic filter.

Production of mercury

131. Materials handling and storage In addition to the generic BAT for materials handling and storage, because of the vapour pressure of mercury, storage of the product in sealed and iso-lated flasks is considered to be BAT.

132. Process selection for mercury production : The Best Available Technology to produce mercury is the production of mercury from secondary raw materials. Only in situations were waste mercury cannot be obtained, for primary mercury production from cinnabar using the Herreschoff furnace is BAT. For other production either from gas treatment systems for other non-ferrous metals or from secondary raw materials it is not possible to conclude that a single production process is BAT.

133. Gas collection and abatement : Best Available Techniques for gas and fume treatment systems are those described for mercury removal. For dust forming process stages a fabric fil-ter is considered to be BAT. BAT for gas collection and abatement for the various process stages are summarized in the following table:

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Ore grinding and conveying. Dust collection and fabric filter.

Handling secondary material Enclosed handling, scrubbing of ventilation gases

Primary or secondary roasting Mercury condenser and mercury scrubber system.

Product handling Enclosed filling station, scrubbing of ventilation gases.

The performance of the scrubber based processes are uncertain for fine mercury particles and it is concluded that further investigation of the techniques in this application is needed before BAT can be confirmed and associated emissions given.

134. The BAT associated emission level for dust from ore grinding, roasting, distillation and as-sociated processes for primary production of mercury is 1-5 mg/Nm³ (daily average). This can be achieved using a fabric filter, while a wet ESP may be applicable to gases from slag granu-lation. Mercury emissions to air from secondary production and production from base metals associated with the use of BAT in the mercury sector are of 0.02 mg/Nm³ (daily average), what can be achieved by a mercury scrubber (Boliden, thiosulphate etc).

Emerging techniques

135. The application of selenium filter is proposed as a dry media process, which can be ap-plied at both steel and non-ferrous metal smelters. Mercury removal of above 90 % has been achieved through this technique reducing the mercury concentrations to below 0.01 mg/m³. Se-lenium filters are recommended for the removal of mercury from the flue gas stream upstream of the acid plant in non-ferrous metal smelters. For copper production, the estimates of the an-nualized cost indicate a range from 1990 US$ 10.0 to more than 50.0 per tonne of copper. In the case of lead smelters this cost is about 50 % lower.

136. The mercury reduction of a selenium scrubber is about 90–95%, resulting in mercury con-centrations of about 0.2 mg/m³. However, at low incoming Hg concentrations the removal effi-ciency can be less than 90 %.

137. For the Odda chloride process, mercury concentrations of the treated gases are 0.05-0.1 mg/m³.

Production of copper and its alloys from primary and secondary raw materials

138. Bath smelting can offer low cost installations because of the potential high reaction rates in modern plant coupled with sealed or semi-sealed furnaces. Plant reliability needs to be proven in the long term.

139. ISA Smelt for reduction/oxidation is not industrially proven but is emerging.

140. The use of hydro-metallurgical processes is also emerging and they are suitable for mixed oxidic/sulphidic ores that contain low concentrations of precious metals. Some pro-cesses are being developed for concentrates and dust treatment based on leaching for exam-ple leach-solvent extraction-electro-win (L:SX:EW) processes.

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141. Developments in other industrial sectors may also be seen as emerging for copper pro-duction processes. Particular developments are: (a) The use of modern fabrics for bag filters mean that more effective and robust fabrics (and housing design) can allow bag life to extended significantly, improving performance and reduc-ing costs at the same time.(b) The use of intelligent damper controls can improve fume capture and reduce fan sizes and hence costs. Sealed charging cars or skips are used with a reverberatory furnace at a sec-ondary aluminium smelter and reduces fugitive emissions to air significantly by containing emissions during charging.

Production of aluminium from secondary raw materials

142. Reuse of filter dust from secondary aluminium production: Dust and fume from a rotary furnace is treated with sodium bicarbonate and activated carbon as the scrubbing medium to remove chlorides produced by the salt flux and sodium chloride is formed. The dust is then col-lected in a fabric filter and can be included with the salt charged to the furnace.

143. Catalytic filter bags.

Production of lead and zinc from primary and secondary raw materials

144. Leaching processes based on chloride for zinc and lead recovery are reported as being at the demonstration stage.

145. The injection of fine material via the tuyeres of a blast furnace has been successfully used and reduces the handling of dusty material and the energy involved in returning the fines to a sinter plant.

146. Control parameters such as temperature are used for melting furnaces and kettles and reduce the amount of zinc and lead that can be fumed from a process.

147. Furnace control systems from other sectors may be available for the blast furnace and ISF.

148. The EZINEX process is based ammonia/ammonium chloride leaching followed by cemen-tation and electrolysis. It was developed for the direct treatment of EAF dusts and one plant is operational. It may be used for richer secondary zinc feed.

149. The Outokumpu Flash Smelting Furnace has been used on a demonstration basis for the production of lead by direct smelting. The use of Waelz kilns for this purpose has also been re-ported. The literature contains many other potential examples that have not yet been devel-oped beyond the pilot scale.

150. For the lead sulfide process, a mercury removal efficiency of 99.0 % has been measured, resulting in mercury emission concentrations of 0.01-0.05 mg/Nm³.

151. The BSN process treats pelletised EAF dust by drying and clinkering followed by the re-duction, volatisation and re-oxidation to produce ZnO.

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Production of gold

152. The 'J' process is not operated in Europe but can operate with a lower inventory of gold compared with other gold refining processes. It uses a re-generable iodine solution to dissolve impure gold (< 99.5%). The gold is reduced by potassium hydroxide, separated, washed and dried to a powder containing 99.995% gold. Liquor from the reduction stage is fed to an elec-trolytic cell where soluble impurities and any unreduced gold iodide are deposited on the cath-ode and removed for recovery in a precious metals circuit. The solution is then transferred to an electrolytic diaphragm cell fitted with inert electrodes. Iodine solution produced in the anode compartment and KOH solution produced in the cathode compartment are recycled

153. A process has been designed to treat a pyrite concentrate that contains microscopic gold particles (< 1 µm) to produce a gold dore, a lead/silver concentrate and a zinc concentrate

Production of mercury

154. A process integrated with primary mercury production is being developed to recover mer-cury that is removed from processes that are substituting other materials for mercury. This de-velopment will include the abatement of fine mercury particles and this technique will be avail-able for primary mercury production.

Overview on ELVs and BAT associated emission levels

155. The Protocol on Heavy Metals includes an ELV for particulate emissions for the produc-tion of copper and zinc, including Imperial Smelting furnaces, of 20 mg/m³, and of 10 mg/m³ for the production of lead. No ELV is specified for the heavy metals covered by the Protocol, nor for the production of mercury or gold.


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Table 8: ELVs for primary and secondary production of non-ferrous metal industry (in mg/Nm³ unless stated otherwise)

Country ELV Remarks


Protocol (Annex V)

2010

production of copper and zinc, including Imperial Smelting furnacesproduction of leadcontinuous (daily) and discontinuous measurements (hourly average)

Austria6 2010

> 5 MW (electric furnace > 3MW); production of Pb and Zn, > 1MW6% O2 solid, 3% O2 liquid and gaseous fuels; continuous (daily) and dis-continuous measurements (half-hour average)

Belgium 1020

primary lead production and meltingprimary production and melting of other non-ferrous metalscontinuous measurements, daily average.

Bulgaria 2010

production of copper and zincproduction of lead

Canada 23

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5050

Secondary Lead Smelters : operations involving the use of holding fur-naces, kettle furnaces or lead oxide production units or involving scrap handling and material handling, crushing, furnace tapping, furnace slagging, furnace cleaning or castingSecondary Lead smelters : operations involving the use of blast fur-naces, cupolas or reverberatory furnacesQuebec regulation for zinc smelting plantsEmission guideline for release concentration of total particulate matter from process air emissions at base metals smelters and refineries

Germany 5

5

production of non-ferrous unrefined metals, roasting, smelting or sintering of non-ferrous metal ores

melting, alloying or refining of non-ferrous metals (non-ferrous metal foundries with a production capacity of > 20 t/d or > 4 t/d for lead and cadmium)continuous (daily) and discontinuous measurements (half-hour aver-age)

Netherlands 1-5 prod. of copper, lead, zinc, gold and mercury; daily average



Primary Copper Smelting: Nonsulfuric acid PM limit of 6.2 mg/dscm for flash smelting furnaces, slag cleaning vessels and batch converters


1-5 prod. of copper, lead, zinc, gold and mercury; daily average

6 The regulation is currently under revision, with the aim to reach an adjustment to the state of the art

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UNECE continuous (daily) and discontinuous measurements (hourly average)

Austria 0.05 additionally common ELV for Cd, Hg, Be, Tl < 0.2 mg/m³; discontinuous measurements (half-hour average)


Canada Base metals smelters and refineries are to develop facility emission re-duction targets for, and timetables to achieve, reductions in releases taking into account facility emission reduction targets for sulphur diox-ide and particulate matter, pollution prevention and control options, and performances for various feeds, smelting processes, and emission con-trol systems

France 0.05 primary and secondary production of lead, zinc and aluminium; if mass flow Cd+Hg+Tl > 1 g/h; additional common ELV of 0.1 mg/Nm³





UNECE continuous (daily) and discontinuous measurements (hourly average)

Austria7 5 Common ELV for Pb, Zn, Cr (except for Cr-VI), Cu, Mn, V, Sn; discon-tinuous measurements (half-hour average)


Canada Base metals smelters and refineries are to develop facility emission re-duction targets for, and timetables to achieve, reductions in releases taking into account facility emission reduction targets for sulphur diox-ide and particulate matter, pollution prevention and control options, and performances for various feeds, smelting processes, and emission con-trol systems


France 1 primary and secondary production of lead, zinc and aluminium; if mass flow Pb and its compounds > 10 g/h

Germany 0.51121

all installations (general requirement); sinter plant: sintering beltprod. of non-ferrous unrefined metals except leadproduction of leadlead refining

7 The regulation is currently under revision, with the aim to reach an adjustment to the state of the art

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common ELV for Pb, Co, Ni, Se, Te and their compounds; continuous (daily) and discontinuous measurements (half-hour average)


Switzerland 15

Production of lead batteryall installations if mass flow > 25 g/h


Primary Lead Smelting: 500 grams of lead per megagram of lead metal producedSecondary Lead Smelting: Lead limit of 2.0 mg/dscm for all furnace types (blast, reverberatory, rotary and electric).


Protocol (Annex V)

continuous (daily) and discontinuous measurements (hourly average)

Austria 0.1 Sum Be and Hg, additionally common ELV for Cd, Hg, Be, Tl < 0.2 mg/m³; discontinuous measurements (half-hour average)


Canada existing primary zinc, lead and copper smelters: 2 g Hg/tonne total pro-duction of finished metals (as of 2008)new and expanding primary zinc, nickel and lead smelters: 0.2 g Hg/tonne production of finished zinc, nickel and leadnew and expanding primary copper smelters: 1 g Hg/tonne of finished copperatmospheric emissions; for new installations additional mercury offset program to ensure no “net” emission increases occur: a new facility will recover and retire an amount of mercury equivalent to their annual emissions.


France 0.05 primary and secondary production of lead, zinc and aluminium; if mass flow Cd+Hg+Tl > 1 g/h; additional common ELV of 0.1 mg/Nm³




References

CEC 2005Community Strategy Concerning Mercury. Commission of the European Communities, COM(2005) 20 final

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CCME 2000 Canada-wide Standards for Mercury Emissions. Canadian Council of Ministers of the Environ-ment, Quebec, June 5-6, 2000

EC 2001Ambient air pollution by mercury - Position Paper. European Communities, Luxembourg, 2001.

Environment Canada 2002Multi-pollutant emission reduction analysis foundation (MERAF) for the base metals smelting sector : final report. September 17, 2002.

Environment Canada 2006Environmental Code of Practice for Base Metals Smelters and Refineries : Code of Practice, Canadian Environmental Protection Act, 1999. First edition. March 2006.

EIPPCB 2001Integrated Pollution Prevention and Control: Reference Document on Best Available Tech-niques in the Non Ferrous Metals Industries. European IPPC Bureau, Sevilla: December 2001.

Hatch Consulting 2002Proposed Emissions Standards for Total Particulate Matter and Sulphur Dioxide for the Base Metals Smelting Sector. Prepared for Environment Canada, March 2002.

Hatch Consulting 2004Guidance Document for Management of Wastes from the Base Metals Smelting Sector. Pre-pared for Environment Canada, March 2004.

Miller and Jones, 2005Mercury and Modern Gold Mining in Nevada. Greg Jones, Glenn Miller. Dept. of Natural Re-sources and Environmental Sciences. University of Nevada. October 24, 2005

UNEP 2002Global Mercury Assessment. United Nations Environment Programme, UNEP Chemicals, Geneva, December 2002.

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CEMENT INDUSTRY

Background

157. This category covers installations for the production of cement clinker in rotary kilns with a production capacity exceeding 500 tonnes per day, or in other furnaces with a production ca-pacity exceeding 50 tonnes per day. According to annex III of the Protocol, BAT are considered for fossil fuel fired kilns. The co-incineration of waste in cement kilns is treated within the waste incineration category.

158. According to Annex III, in terms of energy demand and emission control opportunities, ro-tary kilns with cyclone preheaters are preferable for clinker production. For heat recovery pur-poses, rotary kiln off-gases are conducted through the preheating system and the mill dryers (where installed) before being dedusted, and the collected dust is returned to the feed material. Based on annex III, less than 0.5% of lead and cadmium entering the kiln is released in ex-haust gases. The high alkali content and the scrubbing action in the kiln favour metal retention in the clinker or kiln dust. The emissions of heavy metals into the air can be reduced by, for in-stance, taking off a bleed stream and stockpiling the collected dust instead of returning it to the raw feed. However, in each case these considerations should be weighed against the conse-quences of releasing the heavy metals into the waste stockpile. Another possibility is the hot-meal bypass, where calcined hot-meal is in part discharged right in front of the kiln entrance and fed to the cement preparation plant. Alternatively, the dust can be added to the clinker. An-other important measure is a very well controlled steady operation of the kiln in order to avoid emergency shut-offs of the electrostatic precipitators (ESPs). It is important to avoid high peaks of heavy metal emissions in the event of such an emergency shut-off. To reduce direct dust emissions from crushers, mills, and dryers, fabric filters (FFs) are mainly used, whereas kiln and clinker cooler waste gases are controlled by fabric filters or electrostatic precipitators. With ESP, dust can be reduced to concentrations below 50 mg/m3. When FF are used, the clean gas dust content can be reduced to 10 mg/m3 (273 K, 101.3kPa, dry gas).


159. The selected process has a major impact on the energy use and air emissions from the manufacture of cement clinker. For new plants and major upgrades, according to the BREF, the best available technique for the production of cement clinker is considered to be a dry process kiln with multi-stage preheating and precalcination. Based on the BREF document, the associated BAT heat balance value is 3000 MJ/tonne clinker. It is expected that all the non-dry kilns will convert to the dry method when they are renewed

160. The best available techniques for the manufacturing of cement with regard to particulate matter (PM) and heavy metals emissions includes the following general primary measures:- A smooth and stable kiln process, operating close to the process parameter set points, is

beneficial for all kiln emissions as well as the energy use. - Minimising fuel energy use.- Careful selection and control of substances entering the kiln can reduce emissions. When

practicable selection of raw materials and fuels with low contents of sulphur, nitrogen, chlo-rine, metals and volatile organic compounds should be preferred.

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161. Fugitive emission sources mainly arise from storage and handling of raw materials, fuels and clinker and from vehicle traffic at the manufacturing site. A simple and linear site layout is advisable to minimise possible sources of fugitive dust. Proper and complete maintenance of the installation generally has the indirect result of reducing fugitive PM by reducing air leakage and spillage points. The use of automatic devices and control systems also helps fugitive dust reduction, as well as continuous trouble-free operation.

162. Some techniques for fugitive PM abatement are:- Open pile wind protection. Outdoor storage piles of dusty materials should be avoided, but

when they do exist it is possible to reduce fugitive dust by using properly designed wind barriers.

- Water spray and chemical dust suppressors. When the point source of dust is well localised a water spray injection system can be installed.

- Paving areas used by lorries, road wetting and housekeeping.- Mobile and stationary vacuum cleaning. During maintenance operations or in case of trou-

ble with conveying systems, spillage of materials can take place. To prevent the formation of fugitive dust during removal operations, vacuum systems should be used.

- Ventilation and collection in fabric filters. As far as possible, all material handling should be conducted in closed systems maintained under negative pressure. The suction air for this purpose is then de-dusted by a fabric filter before emitted into the atmosphere.

- Closed storage with automatic handling system. Clinker silos and closed fully automated raw material storage are considered the most efficient solution to the problem of fugitive dust generated by high volume stocks. These types of storage are equipped with one or more fabric filters to prevent fugitive dust formation in loading and unloading operations.

163. According to the BREF, BAT for reducing dust emissions are the combination of the above described general primary measures and:a) Minimisation/prevention of dust emissions from fugitive sourcesb) Efficient removal of particulate matter from point sources by application of:

- Electrostatic precipitators with fast measuring and control equipment to minimise the number of carbon monoxide trips

- Fabric filters with multiple compartments and ‘burst bag detectors’

164. In contrast to the BAT description in the HM Protocol, according to the BREF, the BAT emission level for dust associated with these techniques is 20-30 mg/m³ on a daily average ba-sis. This emission level can be achieved by electrostatic precipitators and/or fabric filters at the various types of installations in the cement industry. The best installations achieve emission levels below 10 mg/m³ (273 K, 101.3 kPa, 10% oxygen, dry gas).

165. In general, available information indicates that there is no major difference in heavy metal emissions between the different process types (e.g. wet or dry kilns), or between kilns burning different fuels (e.g. conventional fuels or waste derived fuels). This is because it is the raw ma-terial input and not the process type which has the greater effect on heavy metal emissions. Mercury is primarily introduced into the kiln with raw-materials (usually about 90% of the mer-cury is in the material input) with generally a minor amount (about 10%) coming from the fuels.

166. The best way to reduce heavy metal emissions is to avoid using feed materials with a high content of volatile metals such as mercury. Mercury can build up over time in the cement kilns dust, which is usually returned to the kiln system. When high build-ups occur in the dust, emissions may increase. This can be remedied by discarding the cement kiln dust rather than returning it to the raw material. As metals are often bound to dust, particulate abatement meth-ods will help to reduce HM emissions.

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Emerging techniques

167. Fluidised bed cement manufacturing technology: This process is expected to reduce heat use by 10-12%.

168. A way to minimize mercury emissions is to lower the exhaust temperature. When high concentrations of volatile metals (especially mercury) occur, adsorption on activated carbon is an option.

169. The energy content of emissions can be reduced further by replacing clinker in cement by slag from the production of iron (BOF slag). For more information: http://www.ecocem.ie and http://www.epa.gov/epaoswer/non-hw/procure/products/cement.htm


170. The Protocol on Heavy Metals includes an ELV for particulate emissions for the produc-tion of cement of 50 mg/m³ (273 K, 101.3 kPa, dry gas). No ELV is specified for the heavy met-als covered by the Protocol.


Table 9: ELVs for cement industry (in mg/Nm³ unless stated otherwise)

Country ELV Remarks


Protocol (Annex V)

50 continuous (daily) and discontinuous measurements (hourly average)

Austria8 50 continuous (daily) and discontinuous measurements (half-hour aver-age) (10% O2)

Belgium 15050

all installations if mass flow ≤ 500 g/hall installations if mass flow > 500 g/hcontinuous measurements, daily average.

Bulgaria 50

Czech Republic

50

Germany 20 10% O2; continuous (daily) and discontinuous measurements (half-hour average)

Netherlands 15 8 hour average

8 The regulation is under revision, with the aim to reach an adjustment to the state of the art.

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http://www.epa.gov/epaoswer/non-hw/procure/products/cement.htm

Slovakia 50



The ELV for new and existing installations = 0.15kg of PM per Mg of feed (dry basis) to kiln, based on continuous basis.


20-30 These are the reported achievable concentrations with application of BAT from European BREF documents, at 10 % O2, daily average


Austria 0.1 discontinuous measurements (half-hour average)


France 0.2 common ELV for Cd, Ti, Hg

Germany 0.05 10% O2; alternatively < 0.15 g/hcommon ELV for Cd and As and their compounds, Benzo(a)pyren, wa-ter soluble Co compounds, Cr(VI) compounds; continuous (daily) and discontinuous measurements (half-hour average)



Austria 1 common ELV for Pb, Co, Ni, As; discontinuous measurements (half-hour average)



France 5 common ELV for Sb, Cr, Cu, Sn, Mn, Pb, V, Zn

Germany 0.5 10% O2; common ELV for Pb, Co, Ni, Se, Te and their compounds; continuous (daily) and discontinuous measurements (half-hour aver-age)

Netherlands 1 8 hour average





France 0.2 common ELV for Cd, Ti, Hg

Germany 0.05 10% O2; alternatively < 0.25 g/h; continuous (daily) and discontinuous measurements (half-hour average)

Netherlands 0.05 8 hour average


70

References

EC 2001Economic Evaluation of Air Quality Targets for Heavy Metals. European Commission, Entec UK Limited, January 2001.

EC 2001aAmbient air pollution by mercury - Position Paper. European Communities, Luxembourg, 2001.

Environment Canada 2004Foundation Report on the Cement Manufacturing Sector. December, 2004.

EIPPCB 2001Integrated Pollution Prevention and Control: Reference Document on Best Available Tech-niques in the Cement and Lime Manufacturing Industries. European IPPC Bureau, Sevilla: De-cember 2001.

U.S. EPA, 1999National Emission Standards for Hazardous Air Pollutants for Portland Cement Manufacturing Industry; Final Rule, 64 Federal Register 31898. United States Environmental Protection Agency. 14 June 1999.

71

GLASS INDUSTRY

Background

172. This category covers installations for the manufacture of glass using lead in the process with a melting capacity exceeding 20 tonnes per day. According to annex III, best available techniques (BAT) are considered for the production of glass using lead in the process, includ-ing the recycling of lead containing glass.

173. Lead is used in fluxes and colouring agents in the frit industry, in some special glasses (e.g. coloured glasses, CRT funnels) and domestic glass products (lead crystal glasses). Exter-nal cullet is an important source of metal contamination particularly for lead.

174. According to annex III, dust emissions stem mainly from batch mixing, furnaces, diffuse leakages from furnace openings, and finishing and blasting of glass products. They depend no-tably on the type of fuel used, the furnace type and the type of glass produced. Oxy-fuel burn-ers can reduce waste gas volume and flue dust production by 60%. The lead emissions from electrical heating are considerably lower than from oil/gas-firing. During the melting cycle using discontinuous furnaces, the dust emission varies greatly. The dust emissions from crystal glass tanks (<5 kg/Mg melted glass) are higher than from other tanks (<1 kg/Mg melted soda and potash glass). Some measures to reduce direct metal-containing dust emissions are: pelleting the glass batch, changing the heating system from oil/gas-firing to electrical heating, charging a larger share of glass returns in the batch, and applying a better selection of raw materials (size distribution) and recycled glass (avoiding lead-containing fractions). Exhaust gases can be cleaned in fabric filters, reducing the emissions below 10 mg/m3. With electrostatic precipita-tors 30 mg/m3 is achieved.


175. Related to the category description, the production of container glass, flat glass, domestic glass, special glass and frits may be of concern, due to the potential use of lead oxides as raw material or the use of cullet that may comprise lead containing glasses. The BATs described in this subsection are primarily based on the European BAT reference (BREF) document (EIP-PCB, 2001) and are valid for the production of all these types of glass mentioned if not stated otherwise.

Materials Storage and Handling

176. Bulk powder materials are usually stored in silos, and emissions can be minimised by us-ing enclosed silos, which are vented to suitable dust abatement equipment such as fabric fil-ters. Where practicable collected material can be returned to the silo or recycled to the furnace. Where the amount of material used does not require the use of silos, fine materials can be stored in enclosed containers or sealed bags. Stockpiles of coarse dusty materials can be stored under cover to prevent wind born emissions. Where dust is a particular problem, some installations may require the use of road cleaning vehicles and water damping techniques.

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177. Where materials are transported by above ground conveyors some type of enclosure to provide wind protection is necessary to prevent substantial material loss. These systems can be designed to enclose the conveyor on all sides. Where pneumatic conveying is used it is im-portant to provide a sealed system with a filter to clean the transport air before release. To re-duce dust during conveying and "carry-over" of fine particles out of the furnace, a percentage of water can be maintained in the batch, usually 0 - 4 %.

178. An area where dust emissions are common is the furnace feed area. The main tech-niques for controlling emissions in this area are:- Batch moisture.- Slight negative pressure within the furnace (only applicable as an inherent aspect of opera-

tion).- Provision of extraction, which vents to a filter system, (common in cold top melters).- Enclosed screw feeders.- Enclosure of feed pockets (cooling may be necessary).

179. In potentially very dusty areas such as batch plants the buildings can be designed with the minimum of openings and doors, or dust curtains can be provided where necessary. In the furnace buildings it is often necessary to ensure a degree of natural cooling and so vents etc are provided. It is important to ensure a good standard of house keeping and that all dust con-trol measures (seals, extraction etc.) are properly functioning.

180. Areas of the process where dust is likely to be generated (e.g. bag opening, frit batch mixing, fabric filter dust disposal, etc) can be provided with extraction which vents to suitable abatement plant. This can be important at smaller installations where a higher degree of man-ual handling takes place. All of these techniques are particularly relevant where more toxic raw materials are handled and stored, e.g. lead oxide.

Particulate matter and heavy metals

181. In general, BAT for controlling dust emissions from furnaces in the glass industry is the use of either an electrostatic precipitator (ESP) or fabric filter system, operating where appro-priate, in conjunction with a dry or semi-dry acid gas scrubbing system. The BAT emission level for dust associated with these techniques is 5 - 30 mg/Nm³ which generally equates to less than 0.1 kg/tonne of glass melted. Values in the lower part of the range given would generally be expected for bag filter systems. In some cases, the application of BAT for metals emissions may result in lower emission levels for dust. Secondary dust abatement represents BAT for most glass furnaces, unless equivalent emissions can be achieved with primary measures.

182. Glass manufacturing facilities in the US typically control PM emissions using an ESP, or a fabric filter (FF) using acid and temperature resistant filters. Acid gases are controlled using a Dry Injection FF/ Dry Lime Scrubber combination, or a wet scrubber. U.S. EPA has found that ESPs are most effective for reduction of heavy metals in furnace gases. ESPs achieve about 95% reduction in fine PM and metal fumes, and can easily handle the high temperature gases from furnaces. Although generally a FF is expected to achieve at least 99% efficiency for re-moval of PM, this level is not achieved at the high temperatures and fine PM characteristic of the glass manufacturing industry. However, a FF can be engineered to achieve similar results (e.g., fitted with high-temperature resistant, acid gas resistant filters).

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183. In general in this sector, BAT is considered to be raw material selection to minimise emis-sions of heavy metals, combined with acid gas scrubbing and dust abatement, where appropri-ate. The emission level associated with BAT for metals including lead (As, Co, Ni, Se, Cr, Sb, Pb, Cu, Mn, V, Sn) is <5 mg/ Nm³.

Domestic Glass

184. In general and where it is economically viable, predominantly electrical melting is consid-ered BAT for lead crystal, crystal glass and opal glass production, since this technique allows efficient control of potential emissions of volatile elements. Where crystal glass is produced with a less volatile formulation, other techniques may be considered when determining BAT for a particular installation.

Downstream processes

185. For the production of container glass, the main potential source of emissions from down-stream processes is hot end coating treatment. A number of techniques can be used to treat emissions. Hot end treatment fumes may also be treated with the furnace waste gases in a common acid gas/dust abatement system. The emission level associated with BAT is < 20 mg/Nm3 for particulate matter (PM).

186. For flat glass processing, a number of techniques can be used to treat downstream emis-sions. The emission levels associated with BAT are < 20 mg/Nm3 for particulates and <5 mg/Nm³ for metals including lead (As, Co, Ni, Se, Cr, Sb, Pb, Cu, Mn, V, Sn).

187. Potential emissions from downstream processes in the domestic glass sector consist mainly of dust and acid gas fumes from lead crystal and crystal glass production. For poten-tially dusty activities BAT is considered to be cutting under liquid where practicable, and if dry cutting or grinding is carried out then extraction to a bag filter system. The emission level asso-ciated with BAT for particulates is <10 mg/Nm³, and for metals including lead (As, Co, Ni, Se, Cr, Sb, Pb, Cu, Mn, V, Sn) is <5 mg/Nm³.

188. For the production of special glass, the emissions associated with downstream process-ing can be very variable and a wide range of primary and secondary techniques can be used. For potentially dusty activities BAT is considered to be dust minimisation by cutting, grinding or polishing under liquid, or where dry operations are carried out extraction to a bag filter system. The emission level associated with BAT for particulates as well as for metals including lead (As, Co, Ni, Se, Cr, Sb, Pb, Cu, Mn, V, Sn) is <5 mg/Nm³.

189. In frits production, the only likely emission from downstream processes is dust and BAT is considered to be the use of a bag filter system. The emission levels associated with BAT are considered to be 5 - 10 mg/Nm3 for particulate and <5 mg/Nm3 for metals (As, Co, Ni, Se, Cr, Sb, Pb, Cu, Mn, V, Sn).

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Emerging techniques

190. The Plasma Melter makes use of the electrical conductivity of molten glass and operates with negligible dust emissions. It is however not expected to be a viable technique for melting within the foreseeable future.


191. The Protocol on Heavy Metals includes an emission limit value (ELV) for lead emissions for the production of glass of 5 mg/m³. No ELV is specified for particulate emissions nor for the emissions of cadmium and mercury.


Table 10: ELVs for glass industry (in mg/Nm³ unless stated otherwise)

Country ELV Remarks

ELVs for particulate matter (PM) emissions

Austria 50 O2 reference: 8% flame heated tanks; 13% day tanks; actual O2 electric fur-naces; 21% Oxy fuel melting; continuous (daily) and discontinuous meas-urements (half-hour average)

Belgium 50 continuous measurements, daily average.

Germany 20 melting capacity >20 t/d;8% O2 for flame-heated glass melting furnaces, 13% O2 for flame-heated pot furnaces and day tanks, special provisions for oxygen fuel fired and electrically heated glass melting tanks; continuous (daily) and discontinuous meas-urements (half-hour average)

Netherlands 5-30 equates to < 0,1 kg/tonne of glass melted



0.1-0.13 g PM per Kg glass produced

The ELVs for lead glass manufacturing installations built after 1980 are 0.1 g PM per kg glass produced (0.1 g/Kg) for furnaces with gaseous fuel and 0.13 g/Kg for furnaces with liquid fuel (U.S. EPA, 1980).


5-30< 20< 105-10

furnaces; equates to < 0.1 kg/tonne of glass melted; downstream processes: container glass, flat glass downstream processes: domestic glassdownstream processes: fritsThese values are considered the achievable concentrations by using BAT as defined in the BREF document EIPPCB, 2001); 8 Vol% O2

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continuous melters, 13 Vol% O2 discontinuous melters (except oxy-fuel fired systems)


Austria 0.1 O2 reference: 8% flame heated tanks; 13% day tanks; actual O2 electric fur-naces; 21% Oxy fuel melting; discontinuous measurements (half-hour av-erage)

Belgium 0.25

special glassother glass; common ELV for Cr, Vi, Pb, Cd, Sb, Ni, Co, Se, V;discontinuous measurements.

France 0.05 if mass flow Cd+Hg+Tl > 1 g/h; additional common ELV of 0.1 mg/Nm³

Germany 0.050.5

0.2

other glass, alternatively < 0.15 g/hcontainer glass, common ELV for Cd and As and their compounds, Benzo(a)pyren, wa-ter soluble Co compounds, Cr(VI) compoundsELV for Cd only; if cadmium compounds are used as colouring agents for quality reasons and Cd mass flow < 0.5 g/h;Melting capacity >20 t/d; 8% O2 for flame-heated glass melting furnaces, 13% O2 for flame-heated pot furnaces and day tanks, special provisions for oxygen fuel fired and electrically heated glass melting tanks; continuous (daily) and discontinuous measurements (half-hour average)




Protocol (Annex V)

5 continuous (daily) and discontinuous measurements (hourly average)

Austria 5 Common ELV for Cd, As, Co, Ni, Se, Sb, Pb, Cr, Cu, Mn; O2 reference: 8% flame heated tanks; 13% day tanks; actual O2 electric furnaces; 21% Oxy fuel melting; discontinuous measurements (half-hour average)

Belgium 55

special glassother glass; common ELV for Cr, Vi, Pb, Cd, Sb, Ni, Co, Se, V;discontinuous measurements.


France 31

CRT funnelsother glassif mass flow Pb and its compounds > 5 g/h

Germany 0.53

0.8

if lead is required for product qualitycommon ELV for Pb, Co, Ni, Se, Te and their compounds; ELV for Pb and its compounds only; container glass using foreign cul-let; additionally common ELV for Pb, Co, Ni, Se, Te and their com-pounds < 1.3 mg/Nm³Melting capacity >20 t/d; 8% O2 for flame-heated glass melting fur-naces, 13% O2 for flame-heated pot furnaces and day tanks, special

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provisions for oxygen fuel fired and electrically heated glass melting tanks; continuous (daily) and discontinuous measurements (half-hour average)



BAT accord-ing to the

BREF

< 5 These values are considered the achievable concentrations by using BAT as defined in the BREF document EIPPCB, 2001); Common BAT level for As, Co, Ni, Se, Cr, Sb, Pb, Cu, Mn, V, Sn; furnaces and down stream processes; at 8 % O2 by volume for continuous melters and 13 % O2 by volume for discontinuous melters (except oxy-fuel fired sys-tems)




France 0.05 basic oxygen furnace if mass flow Cd+Hg+Tl > 1 g/h; additional com-mon ELV of 0.1 mg/Nm³

Germany 0.05 melting capacity >20 t/d;; alternatively < 0.25 g/h8% O2 for flame-heated glass melting furnaces, 13% O2 for flame-heated pot furnaces and day tanks, special provisions for oxygen fuel fired and electrically heated glass melting tanks; continuous (daily) and discontinuous measurements (half-hour average)



78

References

EIPPCB 2001Integrated Pollution Prevention and Control: Reference Document on Best Available Tech-niques in the Glass Manufacturing Industry. European IPPC Bureau, Sevilla: December 2001.

Marinshaw and Parrish, 2006Characterization of the Glass Manufacturing Industry for Glass Manufacturing Area Source NE-SHAP (Draft). Memorandum from R. Marinshaw and K. Parrish, of Research Triangle Institute to Susan Fairchild, of U.S. Environmental Protection Agency. May 5, 2006.

U.S. EPA, 1980New Source Performance Standard (NSPS). United States Environmental Protection Agency. 60 Code of Federal Regulations (CFR) Subpart CC. Standards of Performance for Glass Manufacturing Plants. 1980.

79

CHLOR-ALKALI INDUSTRY

Background

193. This category covers installations for chlor-alkali production by electrolysis using the mer-cury cell process.

194. The use of mercury-cell technology has been declining in Europe and North America over the past few decades, as many such plants have shut down or been converted to non-mercury processes. Moreover, European and North American producers are committed to not building any new mercury-cell facilities. In addition, North American and European regulations do not al-low the construction of these facilities. The total phase-out of the mercury process for chlor-al-kali production by the year 2010 was recommended by the Commission for the Protection of the Marine Environment of the North-East Atlantic (OSPARCOM) in its PARCOM decision 90/3 of 14 June 1990, which was reviewed in 1999-2001 without any changes.

195. According to Best Available Techniques (BATs) as described in annex III, with regard to emissions into air, Hg diffusely emitted from the cells to the cell room are particularly relevant. Preventive measures and control are of great importance and should be prioritized according to the relative importance of each source at a particular installation. In any case specific control measures are required when mercury is recovered from sludges resulting from the process. The following measures can be taken to reduce emissions from existing mercury process plants:- Process control and technical measures to optimize cell operation, maintenance and more

efficient working methods;- Coverings, sealings and controlled bleeding-off by suction;- Cleaning of cell rooms and measures that make it easier to keep them clean; and- Cleaning of limited gas streams (certain contaminated air streams and hydrogen gas).Based on Annex III, these measures can cut mercury emissions to values well below 2.0 g/Mg of Cl2 production capacity, expressed as an annual average. There are examples of plants that achieve emissions well below 1.0 g/Mg of Cl2 production capacity. The membrane process re-sults in no direct mercury emissions. Moreover, the global energy balance shows a slight ad-vantage for membrane cell technology in the range of 10 to 15% and a more compact cell op-eration. It is, therefore, considered as the preferred option for new plants. PARCOM decision 90/3 of 14 June 1990 of the Commission for the Prevention of Marine Pollution from Land-based Sources (OSPARCOM) recommends that existing mercury cell chlor-alkali plants should be phased out as soon as practicable with the objective of phasing them out completely by 2010. As a result of PARCOM decision 90/3, existing mercury-based chlor-alkali plants were required to meet the level of 2 g of Hg/Mg of Cl2 by 31 December 1996.


196. The selected process technology has a major impact on the energy use and emissions from the manufacture of chlor-alkali. According to the BREF, best available techniques for the production of chlor-alkali is considered to be membrane technology. Non-asbestos diaphragm technology can also be considered as BAT.

81

197. Mercury releases from chlor-alkali operations can be entirely eliminated only by convert-ing to a non-mercury process such as the membrane cell process. Conversion to membrane cell technology is considered as BAT in the BREF document for chlor-alkali production under the IPPC Directive. Conversions and closures of mercury-cell chlor-alkali plants are being car-ried out faster in some OSPARCOM countries than in others.

198. Among OSPARCOM countries and in the EU there has been considerable discussion about the possible impacts the re-marketing of the mercury from decommissioned chlor-alkali facilities will have on the global mercury market. In 1999 all West European chlor-alkali produ-cers presented the authorities with a voluntary commitment, one clause of which commits them not to sell or transfer mercury cells after plant shutdown to any third party for re-use. Euro Chlor signed an agreement with the state-owned Miñas de Almadén of Spain. This agreement stipulates that Miñas de Almadén will accept all surplus mercury from western European chlor-ine producers, under the condition that it displaces, ton for ton, mercury that would otherwise have been newly mined and smelted to satisfy legitimate uses. As a pro-active contribution to a proposed globally organised effort to phase out primary production of mercury and to stop sur-pluses re-entering the market, the Commission intends to propose an amendment to Regula-tion (EC) No. 304/2003 to phase out the export of mercury from the Community by 2011. In North America, to reduce supply, the US Government decided in 2004 to place a large quantity of previously stockpiled mercury into long-term storage (at least 40 years) to prevent it from en-tering the market (U.S. DNSC, 2004).

199. During the remaining life of mercury cell plants, all possible measures should be taken to protect the environment as a whole including:a) Minimising mercury losses to air by:

- use of equipment and materials and, when possible, a lay-out of the plant (for example, dedicated areas for certain activities) that minimise losses of mercury due to evapora-tion and/or spillage

- good housekeeping practices and good maintenance routines- collection and treatment of mercury-containing gas streams from all possible sources,

including hydrogen gas. Sulphur impregnated activated charcoal was used by ICI Corn-wall for the hydrogen filters.

- reduction of mercury levels in caustic sodaAccording to the BREF, the best performing mercury cell plants are achieving total mercury losses to air, water and with products in the range of 0.2-0.5 g Hg per tonne of chlorine ca-pacity as a yearly average, and with regard to air emissions 0.21-0.32 g Hg/Mg Cl2. In the following table mercury emissions from best performing plants in Europe are indicated.

Air emissions from g Hg/tonne chlorine capacity

cell room 0.2-0.3

process exhausts, including Hg distillation unit 0.0003-0.01

untreated cooling air from Hg distillation unit 0.006-0.1

hydrogen gas <0.003

b) Minimising current and future mercury emissions from handling, storage, treatment and dis-posal of mercury-contaminated wastes by:- implementation of a waste management plan drawn up after consultation with the ap-

propriate authorities- minimising the amount of mercury-containing wastes- recycling the mercury contained in wastes when possible- treatment of mercury-contaminated wastes to reduce the mercury content in the wastes

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- stabilisation of residual mercury-contaminated wastes before final disposal.c) Decommissioning carried out in a way that prevents environmental impact during and after

the shutdown process as well as safeguarding human health

200. Major points of mercury emission generation in the mercury cell process of chlor-alkali production include: byproduct hydrogen stream, end box ventilation air, and cell room ventila-tion air. Typical devices/techniques for removal of mercury in these points are: - gas stream cooling to remove mercury from hydrogen stream, - mist eliminators, - scrubbers, and - adsorption on activated carbon and molecular sieves. The installation of the above mentioned devices can remove mercury with the efficiency of more than 90 %.

201. However, most mercury losses from chlor-alkali facilities are fugitive. Relevant preventive measures include:- Equipment cool-down before opening for invasive maintenance;- Consolidation of maintenance actions to minimize the number of invasive maintenance

events; - Draining mercury from components before they are opened or keeping the internal mercury

covered with cooling water or installing a hood to capture mercury vapour;- Capital investment in larger-capacity decomposers that require less invasive maintenance;- Improving the purity of brine so as to prevent build-up of mercury wastes that require inva-

sive maintenance;- Use of longer-lasting metallic anodes that necessitate less invasive maintenance; DSA’s

were used in Canada: Dimensionally Stable Anodes (DSA) replaced graphite (carbon) an-odes that were the cause of many chlorinated organic substances released

- Capital investment in new elongated cells with air pollution prevention features like internal mechanical arms that can accomplish some maintenance actions that formerly required in-vasive maintenance.

202. In the U.S. regulation for chlor-alkali plants there are no ELVs for “total” emissions from these facilities or for “cell rooms.” Instead, stringent workplace standards are required in U.S. to minimize emissions from cell rooms or, as an alternative, facilities can implement a cell room monitoring program. Also, the U.S. regulation does include ELVs for certain vents, as shown in the ELV table below. The stringent work place practices to reduce emissions, include:a) Use of specific equipment (e.g., smooth interior pipes, fixed covers, head space routed to

ventilation system etc....)b) Preventive Operations (e.g., cool electroplate and decomposer before opening, keep mer-

cury covered with aqueous liquid at temperature below its boiling point, and gas stream cooling to remove mercury from hydrogen stream). For more details see the U.S. regula-tion (U.S. EPA, 2003).

203. Based on OSPAR 2005, all plants comply with the limit value of 2 g Hg/t Cl2 for air emis-sions in PARCOM Decision 90/3, and it is clear that in many plants, air emissions continue to fall. However, for reported emissions a wide range in actual values from 0.14 to 1.57 g Hg/t Cl2 is shown.

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Emerging techniques

204. Fundamental research programmes related to mercury technology are not being devel-oped since it is very unlikely that any new mercury plants will be built. The only recent improve-ments in mercury cells concern the anode geometry with the aim of improving gas release in order to decrease electrical energy usage and increase anode coating life.


205. The Protocol on Heavy Metals includes an emission limit value (ELV) for mercury for new chloralkali plants of 0.01 grams of mercury per metric tonne of chlorine production capacity (i.e. 0.01 g Hg/tonne Cl2). However, no ELVs for mercury emissions from existing plants are speci-fied in the Protocol. Instead, the Protocol requires Parties to evaluate ELVs for existing chlor-al-kali plants within two years after the date of entry into force of the Protocol. A separate sum-mary of emission limit values and control for the chlor-alkali industry with regard to mercury emissions from existing plants was submitted to WGSR at its 37th session in 2005 (EB.AIR/WG.5/2005/2 Annex I).

206. The following table gives an overview on current ELVs implemented by the Parties. Infor-mation was compiled using Parties’ responses to question 44 of the 2004 questionnaire on Strategies and Policies for Compliance Review and additional information by national experts. For comparison, the table also includes BAT associated emission levels as indicated in the Eu-ropean BREF document. All values are expressed in g Hg/Mg Cl2 production (capacity) as an annual mean value, referring to standard conditions (273.15 K, 101.3 kPa, dry gas), and do not cover start-up and shutdown periods except stated otherwise.

Table 11: ELVs for chlor-alkali plants (in g Hg/tonne chlorine capacity unless stated otherwise)


ence

ELV Remarks

ELVs for mercury (Hg) emissions

Protocol (Annex V)

0.01 new installations, total plant emissions

Belgium 1.52

new installations; existing installations;additionally ELV of 0.2 mg/Nm3 if mass flow 1 g/hphase out of mercury cell process by 2010

Canada 50.10.10.1

existing installations, emissions from cell roomexisting installations, emissions from hydrogen gasexisting installations, emissions from end boxesexisting installations, emissions from retorts/Hg recoveryadditionally ELV of 1.68 kg Hg/day for total plant emissions

Czech Republic

0.012

new installationsexisting installations

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Finland phase out of mercury cell process by 2010

France ELV of 0.05 mg Hg/Nm3 if mass flow Cd+Hg+Tl > 1 g/h; additional com-mon ELV of 0.1 mg/Nm³

Germany 11.2

existing installations; existing installations if alkali lye and dithionite or alcoholates are pro-duced simultaneously in one facility;emissions from cell room and end boxes

Netherlands 1.5 phase out of mercury cell process by 2010

Slovakia 1.5

Sweden phase out of mercury cell process by 2010

Switzerland ELV of 0.2 mg/m³ for all installations if mass flow > 1 g/h


0.00.076

0.033

ELV for total mercury emissions for new installationsELV for mercury from hydrogen streams and end box ventilation sys-tems for existing installations with end box ventilation based on 52 week average of Cl2 produced (not capacity); ELV for mercury from hydrogen streams for existing installations with-out end box ventilation based on 52 week average of Cl2 produced.For cell rooms, no numerical ELV is specified; however, stringent work-place standards are required to minimize emissions from cell rooms or, as an alternative, facilities can implement a cell room monitoring pro-gram. Cell room ventilation emissions of below 1,3 kg/d may be as-sumed when the operator carries out the work practice standards.Also, for all mercury recovery facilities with oven type thermal recovery units, total mercury emissions are not to exceed 23 mg per normal cu-bic meter (mg/Nm³) from each unit vent; and for non-oven type mercury thermal recovery units, emissions are not to exceed 4 mg/Nm³.


0.21-0.32 existing installations, total plant emissions (air, water and products) achievable with application of BAT from European BREF documents.

OSPAR-COM

0.14-1.57 reported emissions of existing installations for 2003, phase out of the mercury process for chlor-alkali production by 2010

References

CEC 2005Community Strategy Concerning Mercury. Commission of the European Communities, COM(2005) 20 final


85

EIPPCB 2001Integrated Pollution Prevention and Control: Reference Document on Best Available Tech-niques in the Chlor-Alkali Manufacturing industry. European IPPC Bureau, Sevilla: December 2001.

OSPAR 2004OSPAR Implementation Report Dec. 90/3: Overview Assessment of Implementation of PAR-COM Decision 90/3 on Reducing Atmospheric Emissions from Existing Chlor-Alkali Plants - Update 2004. OSPAR Commission, 2004.

OSPAR 2005Mercury Losses from the Chlor-Alkali Industry in 2003. OSPAR Commission, 2005.

UNEP 2002Global Mercury Assessment. United Nations Environmental Programme. UNEP Chemicals, December 2002.

U.S. DNSC, 2004. Mercury Management Environmental Impact Statement. United States Defense National Stockpile Center (DNSC). 30 April 2004. 69 Federal Register 23733, 4/30/04.

U.S. EPA, 2003NESHAP for Mercury Emissions from Mercury Cell Chlor-Alkali Plants; Final Rule 68 Federal Register 70904 - 70946, United States Environment Protection Agency. December 19, 2003.

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MUNICIPAL, MEDICAL AND HAZARDOUS WASTE INCINERATION

Background

207. This sector covers installations for the incineration of hazardous or medical waste with a capacity exceeding 1 tonne per hour and for the incineration of municipal waste with a capacity exceeding 3 tonnes per hour, as well as installations for the co-incineration of municipal, medi-cal and hazardous waste. According to annex III, besides emissions abatement measures waste management strategies and alternative waste treatment methods are also considered.

208. There are wastes that are neither classified as hazardous, municipal or medical wastes, depending on national legislation (e.g., non-hazardous industrial wastes, sludge etc.), and thus are not currently taken into account according to annex II. These wastes may be incinerated as well as co-incinerated in other industries, therefore potentially constituting a relevant source of heavy metal emissions. Therefore, additional information is given for these type of wastes. Fur-thermore, there are other thermal waste treatment methods (e.g. pyrolysis) that are not cur-rently taken into account in annex II but may be a relevant source of heavy metal emissions. Therefore, additional information is given for these processes as well.

209. According to annex III, particular actions should be taken both before and after incinera-tion to reduce the emissions of mercury, cadmium and lead. The best available technology (BAT) for reducing particulate matters is considered to be fabric filters in combination with dry or wet methods for controlling volatiles. Electrostatic precipitators (ESPs) in combination with wet systems can also be designed to reach low particulate matters emissions, but they offer fewer opportunities than fabric filters especially with precoating for adsorption of volatile pollu-tants. When BAT is used for cleaning the flue gases, the concentration of particulate matters will be reduced to a range of 10 to 20 mg/m3; in practice lower concentrations are reached, and in some cases concentrations of less than 1 mg/m3 have been reported. The concentra-tion of mercury can be reduced to a range of 0.05 to 0.10 mg/m3, normalized to 11% O2). Heavy metals are found in all fractions of the municipal waste stream (e.g. products, paper, or-ganic materials). Therefore, by reducing the quantity of municipal waste that is incinerated, heavy metal emissions can be reduced. This can be accomplished through various waste man-agement strategies, including recycling programs and the composting of organic materials. In addition, some UNECE countries allow municipal waste to be landfilled. In a properly managed landfill, emissions of cadmium and lead are eliminated and mercury emissions may be lower than with incineration.


210. For BAT as well as in the Waste incineration Directive of the EU, no differentiation is made between municipal, hazardous and medical waste in terms of applied techniques or achievable emission limits (as all types of waste are often incinerated in the same installation).

211. The only relevant primary techniques for preventing emissions of mercury into the air be-fore incinerating are those that prevent or control, if possible, the inclusion of mercury in waste. In some countries mercury-containing components are separated out of the solid waste stream and managed or recycled properly. Removing mercury from the waste stream before it enters the incinerator is much more cost-effective than capturing mercury later from flue gases using

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emissions control devices (e.g., carbon beds or activated carbon injection). Once present in the waste stream, mercury contributes to the need for emission controls on incinerators, special disposal of incinerator residues, landfill leachate treatment etc.

212. Lower emissions of mercury from municipal waste combustors and medical waste inciner-ators can be achieved through product substitution. Although this is potentially applicable to a wide range of components, batteries have received the greatest attention because of their sig-nificant contribution to total mercury content in municipal and medical wastes. The applicability of the product substitution to other areas should be based on technical and economic feasibil-ity.

213. Non-technical measures for preventing and controlling mercury releases from waste streams are:- prohibit mercury in product waste and in process waste from being released directly to the

environment, by means of an effective waste collection service; and- prohibit mercury in product waste and in process waste from being mixed with less hazard-

ous waste in the general waste stream, by ensuring separate collection and treatment.

214. In general, BATs for reducing heavy metals and PM emissions are:- to establish and maintain quality controls over the waste input,- in order to reduce overall emissions, to adopt operational regimes and implement proce-

dures (e.g. continuous rather than batch operation, preventative maintenance systems) in order to minimise as far as practicable planned and unplanned shutdown and start-up oper-ations,

- the optimisation and control of combustion conditions- properly designed, maintained, and operated PM control devices

215. Mercury emissions from MWIs occur in two main forms: elemental mercury and ionic mer-cury. Elemental mercury is not readily removed by conventional emission control devices (such as electrostatic precipitators, fabric filters, scrubbers). However, ionic mercury is captured relat-ively well by some of these devices. Also, some mercury-specific technologies can capture ele-mental mercury (such as sorbent injection). Therefore, in order for elemental mercury to be ef-fectively controlled, it either has to be transformed into ionic mercury (which can then be re-moved by a suitable conventional device) or mercury-specific capture technologies must be ap-plied. In the presence of chloride ions and at combustion chamber temperatures above 850°C a considerable part of mercury is present as HgCl2 in municipal waste incinerators.

216. Between 30 % and 60 % of mercury is retained by high efficiency ESPs or fabric filters (FFs), and flue gas desulfurisation (FGD) systems capture further 10 to 20 %.

217. The following technologies may be used to filter out mercury from waste incinerators and combustors:- Carbon filter beds have been developed for use as a final cleaning stage in waste incinerat-

ors and utility boilers to remove volatile heavy metals (e.g., mercury). Cost effectiveness studies indicate US $513–$1,083 per pound mercury removed using carbon filter beds on waste incinerators.

- Wet scrubbing systems are available in different designs and can be used to control metals. A 90 percent reduction of mercury is possible with a wet scrubber when additives are used. Cost-effectiveness for this technology is estimated to be US $1,600–$4,000 per pound of mercury removed for waste incineration.

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- Selenium filters have been developed to remove elemental mercury. Selenium filters are ef-fective on flue gas streams with inlet mercury concentrations of up to 9 mg/m³.

- Activated carbon injection prior to the ESP or FF: test programs have shown mercury re-movals of 50 to 95 percent. The cost of removing mercury from MWCs using activated car-bon injection is estimated to be US $211–$870 per pound and from Medical Waste Inciner-ators, US $2,000-$4000 per pound. Activated carbon injection is currently used to control mercury emissions from four hazardous waste incinerators and capture efficiencies have ranged from 80% to greater than 90%.

218. BAT is the use of an overall flue-gas treatment (FGT) system that, when combined with the installation as a whole, generally provides for the operational emission levels listed in the following table for releases to air associated with the use of BAT (in mg/Nm³):

non-continu-ous measure-

ments

1/2 hour aver-age

daily average

Total particu-late matter

1-20 1-5 In general the use of fabric filters give the lower levels within these emission ranges. Effective maintenance of dust control systems is very important. En-ergy use can increase as lower emis-sion averages are sought. Controlling dust levels generally reduces metal emissions too.

Mercury and its com-pounds(as Hg)

<0.05 0.001-0.03 0.001-0.02 Adsorption using carbon based reagents is generally required to achieve these emission levels with many wastes - as metallic Hg is more difficult to control than ionic Hg. The precise abatement performance and technique required will depend on the levels and distribution of Hg in the waste. Some waste streams have very highly variable Hg concentrations – waste pretreatment may be required in such cases to prevent peak overload-ing of FGT system capacity.

Total cad-mium and thallium (and their com-pounds ex-pressed as the metals)

0.005-0.05 See comments for Hg. The lower volatility of these metals than Hg means that dust and other metal con-trol methods are more effective at con-trolling these substances than Hg.

sum other metals

0.005 - 0.5 Techniques that control dust levels generally also control these metals

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219. If re-burn of flue gas treatment residues is applied, then suitable measures should be taken to avoid the re-circulation and accumulation of Hg in the installation.

220. For the control of Hg emissions where wet scrubbers are applied as the only or main ef-fective means of total Hg emission control:- the use of a low pH first stage with the addition of specific reagents for ionic Hg removal, in

combination with the following additional measures for the abatement of metallic (elemen-tal) Hg, as required in order to reduce final air emissions to within the BAT emission ranges given for total Hg

- activated carbon injection,- activated carbon or coke filters,

221. For the control of Hg emissions where semi-wet and dry FGT systems are applied, the use of activated carbon or other effective adsorptive reagents for the adsorption of Hg, with the reagent dose rate controlled so that final air emissions are within the BAT emission ranges given for Hg.

222. Selective catalytic reduction (SCR) for control of nitrogen oxides also reduces mercury emissions as a co-benefit by changing it into a form that can be collected by fabric filters.

223. Most Parties require discontinuous monitoring of mercury emissions only, while some consider continuous monitoring as BAT; proven systems for continuous measurements of mer-cury emissions are available on the market.

224. According to the EU-landfill directive 1999/31 EU (version 20/11/2003) only pre-treated waste may be landfilled in the EU-member states and specific requirements have to be fulfilled (e.g. C-content). Under special conditions (e.g. low ph) heavy metals may be mobilized and washed out from the landfills. Considering the integrated emissions, it can not generally be stated, that the emissions from landfills are lower than those from incineration.

Co-incineration of waste and recovered fuel in cement kilns

225. The use of suitable wastes as raw materials can reduce the input of natural resources, but should always be done with satisfactory control on the substances introduced to the kiln process.

226. The use waste fuels may increase the input of metals into the process. As the metals en-tering the kiln system are of varying volatility and because of the high temperature, the hot gases in the cement kiln system contain also gaseous metal compounds. Mass balance inves-tigations show that there is low retention of elements with high volatility in the clinker, resulting in an accumulation of these substances in the kiln system.

227. Volatile metals in material that are fed at the upper end of the kiln or as lump fuel can evaporate. These metals do not pass the primary burning zone and may not be decomposed or bound in the cement clinker. Therefore the use of waste containing volatile metals (mercury, thallium) can result in an increase of the emissions of mercury, thallium when improperly used.

228. In general, the BAT for cement kilns apply (see chapter "cement industry").

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Co-incineration of waste and recovered fuel in combustion installations

229. Certain waste derived fuels may be co-combusted in regular combustion installations such as power plants together with conventional fuels. These secondary fuels include materials like e.g. animal by-products, organic acids, solvents, packing materials and plastics, fuels de-rived from waste (recovered fuels), sludge, tires, agricultural residues, demolition wood etc. Waste derived fuels are mainly solid or liquid with a significant amount of ash. For this reason co-combustion is more or less limited to the application in coal-fired boilers and fluidized bed combustion systems.

230. In general, the BAT for combustion installations apply (see chapter "combustion of fossil fuels in utility and industrial boilers").

231. Co-incineration in large combustion plants should not cause higher emissions than co-combustion in incineration plants. Large combustion plants, designed and operated according to BAT, operate effective techniques and measures for the removal of dust, including partly heavy metals, and other emissions. In general, these techniques can be seen as sufficient and can, therefore, also be considered as BAT for the co-combustion of secondary fuel. The ratio-nale as to which wastes can be used for co-combustion is based of the specifications of the conventional fuel normally burned in the specific plant and its associated measured emission levels. If the range of impurities of the waste, in particular the content of heavy metals, lies within the same range as that from the normally used conventional fuel, the fuel specific BAT applies also for the co-combustion of this secondary fuel. The first BAT choice in this respect is also the careful selection of the type and mass flow of the secondary fuel, together with limiting the percentage of the secondary fuel that can be co-combusted. With regard to heavy metals, this encompasses to avoid Hg entering as an elevated component of the secondary fuel and, when there are large quantities of secondary fuel with high concentrations of heavy metals (es-pecially Hg), to use gasification of the secondary fuel and cleaning of the product gas. How-ever, according to the waste used, the co-combustion of secondary fuel can lead to increased emissions of heavy metals, in particular mercury. In this case the adaptation of flue-gas clean-ing systems and the additional injection of activated carbon with an associated reduction rate of 70 – 85 % for mercury is BAT.

Emerging techniques

232. The PECK process for municipal solid waste treatment [EIPPCB 2005]: Before re-circulat-ing to the grate, fly ashes collected in the boiler and ESP are mixed with dewatered sewage sludge and fed to a pelletiser. The resulting dry pellets are treated in a fluidised bed reactor, where chlorination and evaporation of the metals take place at 900 °C. The evaporated metals leave the fluidised bed reactor together with the flue-gas. By a partial quench the heavy metals are condensed and filtered afterwards. The depleted fly ash, the re-circulate, is removed from the evaporation reactor and fed back through a buffer silo to the grate. The filtered heavy metal concentrate is then transported to the zinc and lead refining industry. Heavy metals like zinc, lead, cadmium and copper are concentrated in the output flows hydroxide sludge, ferrous and copper scrap. The heavy metals flow via the mineral product and the purified flue-gas are negli-gible. The process has been developed for municipal solid wastes but could in principle be ap-plied to other wastes.

233. Heavy metal evaporation process: Fly ash is heated to around 900 ºC in an atmosphere enriched with hydrochloric acid. The heavy metals are volatilised as chlorides and then con-densed on a filter where they concentrate to such an extent that re-cycling may be possible.

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The remaining fly ash is thus cleaned and may be used for construction. When sited on an ex-isting incineration site the flue-gases evolved may be treated in the existing FGT system, and the HCl may be drawn from a wet scrubber. The process has not been demonstrated on a commercial scale plant.

234. Hydro-metallurgical treatment + vitrification: In this process hydrometallurgical treatment allows the removal of heavy metals and salts. The subsequent vitrification of the fly ash pro-duces a slag which may be used for construction. The process is reported to be applicable to several ash compositions and to have been demonstrated on a semi-industrial scale.

Emission Limit Values (ELVs)

235. The Protocol on Heavy Metals includes ELVs for particulate emissions of 10 mg/m³ for hazardous and medical waste incineration and of 25 mg/m³ for municipal waste incineration, and for mercury emissions of 0.05 mg/m³ for hazardous waste incineration and of 0.08 mg/m³ for municipal waste incineration (11% O2, daily average). No ELVs are specified for co-inciner-ation, for lead and cadmium emissions and for the emissions of mercury from medical waste in-cineration. Instead, the Protocol requires Parties to evaluate ELVs for mercury-containing emis-sions from medical waste incineration within two years after the date of entry into force of the Protocol. A separate summary of emission limit values and control for medical waste incinera-tion with regard to mercury emissions was submitted to WGSR at its 37th session (EB.AIR/WG.5/2005/2 Annex II).


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Table 12: ELVs for municipal, medical and hazardous waste incineration (in mg/Nm³ unless stated otherwise)


ence

ELV Remarks


Protocol (Annex V)

1025

hazardous and medical waste incineration municipal waste incineration11% O2; continuous (daily) and discontinuous measurements (hourly average)

Austria 1010-20

10-15

waste incineration (solid fuels: 11% O2, liquid fuels: 3% O2)co-incineration in cement kilns (≤ 40% thermal input, 10% O2) and co-incineration in combustion installations ≤ 100 MW (≤ 40% thermal in-put); sliding scale ELV (≤ 40% thermal input)co-incineration in combustion installations > 100 MW (≤ 40% thermal input); sliding scale ELV (≤ 40% thermal input)continuous measurements, daily average

Belgium 10 municipal, medical and hazardous waste incineration; continuous measurements, daily average.

Bulgaria 10 hazardous waste incineration, 11% O2, daily average.

Czech Republic

10 waste incineration, daily average

Germany 10

20

waste incineration (11% O2, waste oil and pyrolysis gas: 3% O2), co-in-cernation in combustion installations (< 25% thermal input, solid fuels: 6% O2, liquid and gaseous fuels: 3% O2), co-incernation in cement and lime kilns (> 60% thermal input, 11% O2, waste oil and pyrolysis gas: 3% O2; on demand: sliding scale ELV of 10-20 mg/m³ depending of the amount of co-incinerated waste), co-incernation in other installations (> 25% thermal input)co-incernation in cement kilns (< 60% thermal input, 10% O2), in exist-ing combustion installations and if no desulphurication is necessary (< 25% thermal input, solid fuels: 6% O2, liquid and gaseous fuels: 3% O2) and in other installations (< 25% thermal input); continuous measurements; daily average

Netherlands 5 municipal, hazardous and medical waste incineration, 8 hour average

Slovakia 503020

waste incineration, < 1 t/hwaste incineration, 1-3 t/hwaste incineration, > 3 t/h

Switzerland 10 waste incineration, 11% O2


1719

Municipal Waste Combustors (MWCs), new installations (11% O2)MWCs, existing installations > 9.5 tonnes/hr (11% O2)

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502.4 to 2421 to 57

2424

MWCs, existing installations 1.4 to 9.5 tonnes/hr (11% O2)Range for 5 types of hazardous waste combustors, new facilities.Range for 5 types of hazardous waste combustors, existing facilities.Medical Waste incinerators: new installations > 90.9 kg/hr (11% O2)Medical Waste Incinerators: existing installations > 227 kg/hr (11% O2).


BREF

1-5 waste incineration, daily average


Austria 0.05 waste incineration and co-incineration ≤ 40% thermal input (solid fuels: 11% O2, liquid fuels: 3% O2, cement kilns: 10% O2); half-hour average

Belgium 0.05

0.2

0.5

Flanders: Municipal, medical and hazardous waste incineration; com-mon ELV for Cd, Tl; continuous (daily) and discontinuous measure-mentsWalloon: Municipal waste incineration (17% O2), medical waste inciner-ation (9% O2)Walloon: waste oil incineration

Bulgaria 0.05 hazardous waste incineration, 11% O2, daily average.

Czech Republic

0.1 combustion of waste oils

Denmark 0.05 municipal waste incineration, discontinuous measurements

France 0.05 municipal, medical and industrial waste incineration; common ELV for Cd, Tl

Germany 0.05 incineration and co-incernation of waste (> 25% thermal input, > 60% for cement and lime kilns); common ELV for Cd and Tl and their com-pounds; common ELV for Cd and As and their compounds, Benzo(a)pyren, water soluble Co compounds, Cr(VI) compounds; com-mon ELV for Cd, As, Co, Cr and their compounds, Benzo(a)pyren; dis-continuous measurements; 11% O2, waste oil and pyrolysis gas: 3% O2, cement kilns: 10% O2, solid fuels: 6% O2, liquid and gaseous fu-els: 3% O2; minor co-incineration covered to sector-specific regulations

Netherlands 0.05 municipal, hazardous and medical waste incineration, common ELV for Cd, Th; 8 hour average

Slovakia 0.2 waste incineration; common ELV for Hg, Tl, Cd


0.030.07

0.0280.113

MWCs, existing installations > 9.5 tonnes/hr (11% O2)MWCs, existing installations 1.4 to 9.5 tonnes/hr (11% O2)Medical Waste incinerators: new installations > 90.9 kg/hr (11% O2)Medical Waste Incinerators: existing installations > 227 kg/hr (11% O2).


BREF

0.005-0.05 waste incineration, common BAT value for Cd, Tl and their compounds; discontinuous measurements


Austria 0.5 waste incineration and co-incineration ≤ 40% thermal input (solid fuels: 11% O2, liquid fuels: 3% O2, cement kilns: 10% O2); common ELV for

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Pb and 9 other HM; half-hour average

Belgium 0.5

5

Flanders: Municipal, medical and hazardous waste incineration; com-mon ELV for Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V, Sn; continuous (daily) and discontinuous measurements Walloon: common ELV for Pb, Cr, Cu, Mn; municipal waste incineration (17% O2), medical waste incineration (9% O2), waste oil incineration

Czech Republic

1 combustion of waste oils

Denmark 0.5 municipal waste incineration; common ELV for As, Pb, Sb, Cr, Co, Cu, Mn, Ni, V, discontinuous measurements

France 0.5 municipal, medical and industrial waste incineration; common ELV for Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V

Germany 0.5 incineration and co-incernation (> 25% thermal input, > 60% for cement and lime kilns) of waste; common ELV for Sb, As, Pb, Cr, Co, Cu, Mn, Ni, V, Sn and their compounds; discontinuous measurements; 11% O2, waste oil and pyrolysis gas: 3% O2, cement kilns: 10% O2, solid fuels: 6% O2, liquid and gaseous fuels: 3% O2; minor co-incineration covered to sector-specific regulations

Netherlands 0.51

hazardous and medical waste incineration, municipal waste incinerationcommon ELV for HM incl. Pb; 8 hour average

Slovakia 5 waste incineration; common ELV for Pb, Cu, Mn


0.311.2

0.050.85

MWCs, existing installations > 9.5 tonnes per hour (11% O2)MWCs, existing installations 1.4 to 9.5 tonnes per hour (11% O2)Medical Waste incinerators: new installations > 90.9 kg/hr (11% O2)Medical Waste Incinerators: existing installations > 227 kg/hr (11% O2).


BREF

0.005-0.5 waste incineration, common BAT value for other metals except Hg, Cd, Tl and their compounds; discontinuous measurements


Protocol (Annex V)

0.050.08

hazardous waste incinerationmunicipal waste incineration11% O2; continuous (daily) and discontinuous measurements (hourly average)

Austria 0.05 waste incineration and co-incineration ≤ 40% thermal input (solid fuels: 11% O2, liquid fuels: 3% O2, cement kilns: 10% O2); continuous (daily) and discontinuous measurements (half-hour average)

Belgium 0.05

0.2

Flanders: municipal, medical and hazardous waste incineration; con-tinuous (daily) and discontinuous measurementsWalloon: common ELV for Pb, Cr, Cu, Mn; municipal waste incineration (17% O2), medical waste incineration (9% O2)

Bulgaria 0.05 hazardous waste incineration, 11% O2, daily average.

Canada 0.02 municipal and medical waste incineration except conical waste com-

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0.050.070.040.050.07

busters; new or expanding facilities of any size and existing facilities except medical waste incineration < 120 Tonnes/yearhazardous waste incineration; new or expanding facilities of any size;Sewage sludge incineration; new or expanding facilities of any size;medical waste incineration < 120 Tonnes/year; existing facilities hazardous waste incineration; existing facilitiesSewage sludge incineration; existing facilities11% oxygen

Czech Republic

0.080.1

0.05

municipal waste incineration medical waste incinerationco-incineration in cement plants and combustion installations

Denmark 0.05 municipal waste incineration; discontinuous measurements

France 0.05 municipal, medical and industrial waste incineration

Germany 0.03

0.05

incineration of waste (11% O2, waste oil and pyrolysis gas: 3% O2), co-incernation in cement and lime kilns (10% O2), co-incernation in com-bustion installations (solid fuels: 6% O2, liquid and gaseous fuels: 3% O2), co-incernation in other installationsco-incernation in cement kilns (< 60% thermal input), if Hg due to raw materials; 10% O2continuous measurements; daily average

Netherlands 0.05 municipal, hazardous and medical waste incineration, 8 hour average

Slovakia 0.2 waste incineration; common ELV for Hg, Tl, Cd

Switzerland 0.1 waste incineration, 11% O2


0.390.06

0.005 to 0.09

Medical Waste incinerators (11% O2)MWCs, existing installations (11% O2)Range for 5 types of hazardous waste combustors (11% O2)


BREF

0.001-0.02 waste incineration, daily average

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References

CCME 2000 Canada-wide Standards for Mercury Emissions. Canadian Council of Ministers of the Environ-ment, Quebec, June 5-6, 2000


EIPPCB 2005Integrated Pollution Prevention and Control: Reference Document on the Best Available Tech-niques for Waste Incineration. European IPPC Bureau, Sevilla: July 2005.

EPA 2000Draft Report for Mercury Reduction Options. United States Environment Protection Agency, September 2000.

UNEP 2002Global Mercury Assessment. United Nations Environmental Programme Chemicals, 2002.

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