REFRACTORYThe Benefits of Energy Efficiency and

Environmental Friendliness

Giuliano CopettiPrague, June 15th 2016

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Since the very beginning of the industrial era, different aims andstrives have moved the production technologies towards newhorizons and objectives:

• Mirroring the needs and the evolution of the society• Adopting the new emerging ways of thinking of the populations• Following the changes and the challenges of the time.

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Not proper as a substitution of the previous and original social andeconomical values, but rather as their completion and adaptation toa new vision of the world, concepts like…

• Production• Profit• Gain• Expansion• Growth• Volumes• Markets

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…have been often and often paired and accompanied by new onessuch as:

• Health• Safety

• Environment• Resources

• Sustainability• Responsibility

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Having spread all over the industrial world, this “new” conceptshave been, and still continuously are:

• Touching• Influencing• Redefining

also the world of refractory, and especially its very specific branchof monolithic products.

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So, now, question is:

What are the major actual trends influencing monolithicrefractories applications?

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Without being able to present a fully exhausting list, followingfeatures represent some of the most actual trend for this peculiarbranch of the refractory industry.

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1. Shortening and optimization of the delivery time2. Reduction of warehouse stocks.

Sudden decisions from end customer’s side often requireflexible and short delivery times. Planning is suitable to change,and so has to be the whole supply chain. Often refractorycompany are required to act as just-in-time warehouses for theirfinal customers.If compared to the bricks production (considering the differentshapes needed for any single project), these has always beenadvantages for monolithic refractory.Nevertheless, further solutions have to be found to keep onenhancing these features (e.g. new plant layout solutions toincrease flexibility in the production process).

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3. Diversification.How to match products to different application features.

Products specifically designed for different applications.With or without modifying the installation technology.Research & Development, in one word. Again and again.

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4. Waste reduction.

“Zero waste” is not a reachable target, of course.But it has to be a target to follow and follow.Since, more than in the past, and more and more in the future,waste means money. Lot of money. Lost money.

The monolithic concept of “endless lining”, repair just what isconsumed, offers the strongest possibility to reduce thegeneration of wasted materials from the end utilizers’ productioncycle.Recycling is also a way. But if uncontrolled…

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5. Automatizing.How to enhance installation speed. And safety.

Where possible, monolithic refractories offer the possibility toautomatize or, at least, mechanize the installation activity. A fullyunreachable result for other types of refractory products.

Saving time. Since no need to build/dismantle complex holdingstructures anymore…Saving money. Since time of intervention is strongly reduced,and after installation the plant is immediately suitable to operate.

Protecting people. Because safety is not an issue. Not at all.

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6. Energy saving

Fast curing materials and high insulation propertiesgives strong support to energy savings, actingmostly in the same directions:• Less curing time means less fuel consumption.• Higher insulating capability means less thermal dispersion.

Additionally, protected by materials with high insulationproperties, the refractory layers work under conditions of betterthermal uniformity (as well as mechanical one). As aconsequence, less stress induced by thermal variations,reduced possibility of fractures and material losses…

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A case study of fast curing materials:

Seven Refractories“Cement Free Castable”.

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The water added to a castable is distributed in two differentportions:

• the so-called “Imbibition Water”used to wet the whole range of RM grains, and to fill the openporosity.

• the so-called “Reaction Water”needed to react with HAC (High Alumina Cement), forming thehydrated phases.

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During the heating-up process, the imbibition water evaporates,and its complete elimination is a gradual process spread along arather large time window, at a (theoretical) temperature not higherthan 100°C, without any modification of the castable structure.

The width of this time window, necessary to allow all the containedimbibition water to reach the surface and eventually evaporate,strongly depends upon the thickness of the installed castable layer,and therefore strongly impacts the duration of the heating-upprocedure.

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As temperature further increases, once the different hydratedphases reach their own decomposition temperatures, thecorresponding water release becomes a sudden and ratherviolent phenomenon.

Most of these dehydrations take place between 450 and 550°C,and this “reaction water” is released in a more traumatic way (than“imbibition water”): it is like water… “getting free” at a temperaturethat only allows the existence of overheated vapor, with higherspecific volume than the steam at 100°C.

The practical result is that this second step of water elimination isby far the most critical one, and almost all damages areexperienced there.

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An alternative bonding system can be achieved in several ways.

One of these classes of No Cement Castable (NCC) is based onthe utilization of Liquid Colloidal Silica solutions (LCS).

In this case, the complete elimination of the cement means thesubstitution of the hydrated phases with a sol-gel transitionreaction, to guarantee the setting phenomenon.

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As first result, it definitely smoothens the dependency of themechanical characteristics from the temperature. Therefore LCSare very reliable and performing in comparison to the differenttypes of hydraulic bonded cement based refractory castables.

But the main achievement can be considered the strong reductionin the time (and energy) needed to complete the heating-upprocess.

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In fact, in LCS, all the water in the system behaves as “ImbibitionWater”:

no cement no hydration of CA phases no water included in the structural network no water release at the critical T of 450÷550°C.

All the water has already left the refractory mass after vaporizationaround 100°C.

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Therefore LCS, when especially linked to the curing and heating-upprocedures to be applied, are products specifically suitable for allthe applications where time represents a leading factor in thegeneral economy of the required performance.

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Heating-up time reduction derives from:

• the reduced amount of water addition (instead of pure waterthere is a water solution).

• the complete water release taking place around 100°C (withoutrapid and violent residual water release over 400°C, withconsequent potential strong damages of the casted refractorylining).

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Comparison between theoretical heating-up curves:

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HOURS: 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58

800°C

750

700

650

600

550

500

450

400°C

350

300

250

200

150

100°C

50

20°C0

RC‐LCC‐ULCC HEATING CURVE ‐ SCHEMATIC

TEMPE

RATU

RE

HOURS: 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58

800°C

750

700

650

600

550

500

450

400°C

350

300

250

200

150

100°C

50

20°C0

TEMPE

RATU

RE

NCC* HEATING CURVE ‐ SCHEMATIC

LCC NCC - LCS

Referring to application:

• LCS casting technology is fully consolidated and widelyaccepted in the several refractory application fields.

• Other LCS application technologies still present wide“exploration” possibilities. Among them, LCS shot-cretingtechnology is maybe the one that seems to show the largestand most promising expectations of success in the short-medium period of time.

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9. Environment.Really a peculiar and specific issue?

We have already mentioned the “endless lining”, with theconsequent waste reduction capability.Same for the fuel reduction, due to the use of fast curing and highinsulating products, that also helps in the CO2 emission reduction.

Can we call monolithic refractory “environmentally friendly”?For sure, they are – among the refractory products – the closestone to the suistanable economy...

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10. Health and Safety.The human being, above all.

Some peculiar raw material (e.g. the spinel-containing ones) hasmade possible to give up the utilization of Cr derivatives (such asCr2O3 or Chromite) in the refractory formulation.

Performances have been kept at comparable levels, while theexposition of producers’ and utilizers’ workforce to such toxiccomponents has been almost eliminated.

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Better and better performing products for purging plugs andsliding gates have drastically reduced their need of substitution,thus limiting human intervention under heavy operating conditions.

As already mentioned, particular materials and technologies havemade possible repair intervention on blast furnaces from outside,by means of remotely operated equipment.

Potential risks and danger exposures of the people otherwiseinvolved have been therefore strongly reduced.To be noted that an intervention in a Blast Furnace form inside canbe considered as a typical example of Confined Space Entry…

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For the taphole clay production, it is needless to mention theadvantage, in terms of health and safety, of having developedproducts with low (if not even without…) Polycyclic AromaticHydrocarbons content.

The move from the old-fashioned tar-bonded taphole clays, to theactual resin-bonded products, represents one of the most importantsteps of the refractory industry towards ensuring cleanenvironment, health conditions and full compliance with the mostrecent safety regulations.

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A case study of environmentally friendly refractories:

Seven Refractories“Green”

Blast Furnace Taphole Clay

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The main Seven’s concept for THC is that of a:

Continuously OngoingDevelopment Path

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At first, a Consolidated System applied:

…for RAW MATERIALS and LAB CONTROLS:

• Raw material: selection / characterization / control / acceptance.

• Controls and analysis: internal / external

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…for PRODUCTION:

• STS - Seven Traceability System.

• Tolerance control on dry mixing.

• Addition of liquids: quantity control, tolerances management, temperature control, seasonal adjustment.

• Workability control: frequency, time intervals, acceptance procedure.

• Workability measurement devices management.

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…for DELIVERY and CUSTOMER SERVICE:

• Temperature recording (data logging) during shipment and/or transportation.

• Customer support during trials.

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The Consolidated System is coupled with a System Development,which applies working:

…on the STRUCTURE:

• Substitution of tar with resins to achieve an environmental and healthy friendly product.

• Continuous development of different kind of resins to adjust the rates of setting inside of the taphole.

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...on the ADDITIVES:

• Introduction of metallic elements able to form carbide bindings inside the sintered structure:

Me + C —> MeC

• Utilization of carbon black as well as activated carbons to facilitate the formation of MeC.

• Utilization of Nitrides, Azides and Borides to enhance sintering processes due to their anti-oxidization effect.

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…on the IDEAS

• Introduction of Ti Oxides of different purities and in different percentages, with the aim of using THC also as a Ti-carrier, to intervene against localised BF hearth sidewalls consumption.

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And, based on this

Continuously Ongoing Development Path,

Seven Refractories has been able to achieve…

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…the most ENVIRONMENTALLY FRIENDLY

tap hole clay

now available on the market.

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…characterized by having theLOWEST EMISSION LEVEL

of

POLYCYCLIC AROMATICHYDROCARBONS

(PAH)

achievable so far !

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20,300.00 19,700.0018,700.00

15,263.00

12,600.00

9,450.00

6,580.005,740.00

0

5,000

10,000

15,000

20,000

25,000

Compe

titor 1

Compe

titor 2

Compe

titor 3

Compe

titor 4

Compe

titor 5

Compe

titor 6

Compe

titor 7

Compe

titor 8

ppm

COMPETITOR PRODUCTS WITH TARANALYSIS OF POTENTIALLY HARMFUL

TOTAL USEPA 16 PAHs

LOWEST PAH VALUE:5740 ppm

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114.00 66.70 35.00 18.40 13.90 11.00 7.070

5,000

10,000

15,000

20,000

25,000

Compe

titor 9

Compe

titor 10

Compe

titor 11

Compe

titor 12

Compe

titor 13

Compe

titor 14

Compe

titor 15

ppm

COMPETITOR PRODUCTS WITH RESINANALYSIS OF POTENTIALLY HARMFUL

TOTAL USEPA 16 PAHs

HIGHEST VALUE:114 ppm

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114.00

66.70

35.00

18.4013.90 11.00 7.07 3.61 2.87 2.73 1.80

0

20

40

60

80

100

120

Compe

titor 9

Compe

titor 10

Compe

titor 11

Compe

titor 12

Compe

titor 13

Compe

titor 14

Compe

titor 15

Seven Tap 20

0

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0

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5

Seven Tap 05

5 PL

ppm

PRODUCTS WITH RESINfrom “acceptable” to “GREEN”

THANKYOU

• www.sevenrefractories.com

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