green steel making

8/2/2019 Green Steel Making

http://slidepdf.com/reader/full/green-steel-making 1/17

FUTURE GREEN STEELMAKING TECHNOLOGIES

Sara Hornby Anderson, Gary E. Metius, Jim M. McClellandMidrex Technologies Inc.

2725 Water Ridge Parkway, Suite 200Charlotte,

NC 28217Fax: 704 373 1611

[email protected] tel: 704 378 [email protected] tel: 704 378 3334

[email protected] tel: 704 378 3359

Key Words: Greenhouse Gases, Carbon Emissions, CO2 Emissions, Energy, BOF, EAF, EIF™, AlternativeIron Units, Hot Metal, DRI, HBI, Pig Iron, MIDREX®, FASTMET®, FASTMELT®,FASTIRON®, FASTEEL™, FASTOx®, ITmk3®, Mesabi Nuggets, Pig Pellets, COREX®,HIsmelt®

ABSTRACT

Use of the new direct reduction processes, natural gas-based or coal-based, will improve greenhouse gasemissions and lower steelmaking energy requirements while allowing steelmakers to meet end product qualityrequirements. Using steel mill wastes as feedstock will assist steelmakers to achieve zero waste status.

This paper compares carbon dioxide (CO2)/carbon (C) emissions and energy requirements for variousironmaking/steelmaking routes, from the conventional blast furnace (BF)/BOF and MIDREX® DirecReduction Process direct reduced iron (DRI)/hot briquetted iron (HBI)/EAF routes to the new innovativeAlternative Iron Sources (AISs)/steelmaking routes such as the FASTMET Process, the ITmk3 processFASTEEL, FASTOx, COREX and HIsmelt. Definitions of the process technologies considered herein can befound elsewhere in these proceedings in the paper titled “Influence of AIS Chemistry on EAF Steelmaking.” 1

INTRODUCTION

The issue of greenhouse gases emissions is of growing world importance, mandating greenfield primarymetals production facilities incorporate technologies with lower greenhouse gas generation potentialBrownfield steelmills, striving to improve their worldwide competitiveness, are adopting technologies to lowercosts and improve efficiencies, while maintaining or improving product quality.

In the electric arc furnace (EAF) sector, some of these technologies involve the increased use of chemicalenergy to reduce electrical energy requirements and to increase productivity, and alternative iron units (AIUs) toachieve high steel quality. The EAF sector is reviewing emerging AIU technologies, which will assist them in

mailto:[email protected]










achieving better cost competitiveness, production efficiency, and “zero waste” strategies, even without the needfor higher steel quality.

Although efficient operation of metals production facilities should decrease the generation of greenhousegases, significant further emissions reduction requires a better understanding of how and where the greenhousegases originate and what the impact of the new technologies and changing charge materials will be.

In order to identify the options available for achieving a measurable reduction in CO2 emissions, it isnecessary to assemble an overview of the typical levels of CO2 emissions generated in the various stages ofsteel production. Specifically, this paper provides an evaluation of CO2 emissions and energy consumption insteel production, from the receipt of basic raw materials to the tapping of a ladle of liquid steel. The productionroutes considered herein focus primarily on various AIS/EAF options and compare them to the conventionalBF/BOF operations.

The methodology used to analyze the alternative production routes is as follows. The BF/BOF route uses published data for energy inputs and outputs throughout the steelmaking operation and compares data bothcomputed by the authors and presented in DOE report no. EE-0229 2,3,4,5. For the EAF route, an in-house EAFmelt program has been used to predict, from first principles that we have fine tuned using practical experience,

major operating parameters (for example, electrical, flux, oxygen, yield, thermal efficiency of melting, andlevels of sulfur (S) and phosphorus (P) – Table I) given the input AIU composition, percentage charged, EAFslag “V” ratio, final carbon level in the steel, and the desired tap temperature. (It should be noted that productivity changes are partially reflected in the thermal coefficient of melting, but not fully). For each chargescenario, except the FASTMELT, FASTEEL, FASTOx, ITmk3, HIsmelt , COREX, and high (4%) C DRIscenarios, the practices reflect actual industrial data 6,7,8,9,10. In the case of FASTMET, FASTMELT, FASTEELITmk3, and 4%C DRI, two internal mass balance design programs have been used, one for FASTMETFASTEEL, FASTMELT, FASTOx, and ITmk3, which incorporates the Kakogawa FASTMET DemonstrationPlant results 11,12,13, and one for gas-based DRI/HBI, which combines current operating data 6 with prior resultsfor 3.5%C DRI 14 and extrapolates to 4%C DRI production. For FASTOx, where FASMELT HM(FASTIRON) is fed to a BOF, the internal FASTMET 11,12,13 analysis has been coupled with BOF published

data2,3,4,5

. In all cases, the format used for the process operations’ energy input and output, is shown in TableIIa. The results from each individual process’ energy balance computations are then converted to greenhousegas emissions using the conversion factors given in Appendix A. The bases for comparing the process routesare indicated in Tables IIb and IVb of this paper.

ENERGY USE AND CARBON EMISSIONS

Background

Conventional technology based on BF/BOF operations has been the backbone of steel production. The pre-

eminence of these high quality steelmaking operations is being challenged by EAF-based mini mills chargingvarying amounts of AIUs, primarily pig iron and DRI/HBI, with significant quantities of scrap.

The need for cost effective, efficient, high quality steel production has led to many advances in EAFoperations over the past 30 years. Most of these technologies involve the increasing use of chemical energysuch as C and O2 injection and hot, high energy charge materials, to reduce electrical energy requirements andincrease productivity.



The development of new AIUs offers even greater flexibility and competitiveness to EAF steelmakers thanwas available 10 years ago. These AIUs, including pig iron (PI), DRI, HBI, ITmk3 nuggets (“pig pellets” orPP), and hot metal (HM), are and/or would be used primarily to produce high steel quality. Howeverexpanding upon the benefits of educated DRI/HBI use 1,6,7,8,9,10, the novel raw materials offer potential benefitssuch as charge make-up flexibility to ensure minimum cost, maximum productivity, and efficiency, whilereducing greenhouse emissions over the conventional steelmaking techniques 3,4,5.

The potential AIU/scrap combinations are limitless. Those considered herein were chosen to reflect a crossection of proven and future steelmaking operations. Due to the publication constraints, the lengthy nature otabulating the computations, and prior publication of some of the same 3,4,5, the authors intend only to fullydefine the energy balance and greenhouse gas emissions data for the BF/BOF production processes 2,3,4,5 andthose other production processes not previously considered elsewhere 2,3,4. A complete, detailed, analysis can be found at www.midrex.com. All references to tons herein are equivalent to metric tons (1000kg).

Table I. Some EAF Melt Program Specifics for the EAF Charge Combinations ConsideredProcess Met’c

Fe(%)

TotalIron(%)

Blend%C inAIUChge

CarbonChg Inj

(kg/tls)

Ther Meltefficy

Lime(kg/tls)

O2

(Nm3/tls)

MeltPower (kWh/

tls)

SlagVol(kg/tls

Over-all

Yield(t/tls)

89% BF HM - BOF 94.48 94.48 4.0 0 0 91.22 54.30 56.80 -68.27 125.81 0.912

80% FI - BOF 93.90 93.90 4.4 0 0 91.01 68.32 59.28 -50.83 154.38 0.904

80% Cold DRI 86.31 91.85 2.5 0 3.5 83.84 27.90 22.27 546.40 110.52 0.881

80% Hot DRI 86.34 91.85 2.5 0 3.5 85.51 27.90 22.27 407.02 110.52 0.881

80% Hi C CDRI 85.01 90.44 4.0 0 3.5 84.40 27.94 38.80 499.50 110.45 0.871

80% Hi C HDRI 85.01 90.44 4.0 0 3.5 86.10 27.94 38.80 357.96 110.45 0.871

50% CDRI 86.34 91.85 2.5 2 3.5 84.07 31.48 22.05 527.11 102.33 0.905

50% HBI 86.05 92.53 1.5 5 3.5 83.66 31.46 19.68 561.77 102.07 0.908

20% HBI/30% PI

86.0594.51

92.5394.51

1.54.0

0 3.5 85.02 31.05 28.59 447.83 90.69 0.923

50% PP 95.19 95.19 3.5 0 3.5 85.49 26.60 33.86 404.58 72.52 0.939

50% BF HM 94.48 94.48 4.0 0 3.5 88.39 30.79 38.65 167.15 83.33 0.933

50% FASTIRON 93.90 93.90 4.4 0 3.5 88.64 35.01 42.84 146.61 94.22 0.92850% FASTEEL 93.90 93.90 4.4 0 3.5 89.32 35.00 42.84 89.83 94.22 0.928

50% COREX 93.81 93.81 4.6 0 3.5 88.61 32.96 43.33 148.97 88.93 0.929

50% HIsmelt 95.56 95.56 4.0 0 3.5 88.08 22.48 35.02 192.90 56.67 0.945

30% CDRI 86.34 91.85 2.5 3 3.5 84.22 33.75 21.22 514.50 96.72 0.921

30% Hi C CDRI 85.01 90.44 4.0 0 3.5 84.44 33.79 21.00 496.57 96.64 0.917

30% Hi C HDRI 85.01 90.44 4.0 0 3.5 85.05 33.79 21.00 445.55 96.64 0.917

30% HBI 86.05 92.53 1.5 5 3.5 83.98 33.73 20.22 534.96 96.58 0.923

10% FMWO/20% PI

68.5094.51

76.0094.51

2.54.0

0 3.5 84.75 41.73 26.68 470.40 130.70 0.908

10% FMWO/20% PP

68.5095.19

76.0095.19

2.53.5

0 3.5 84.65 39.97 24.74 479.35 126.13 0.911

30% CFMO 79.90 86.80 2.5 2 3.5 84.10 41.54 22.15 524.97 135.76 0.898

30% HFMO

79.90 86.80 2.5 2 3.5 84.74 41.54 22.15 471.48 135.76 0.89830% PP (ITmk3) 95.19 95.19 3.5 0 3.5 85.08 30.78 24.74 442.94 79.01 0.942

30% Pig Iron 94.51 94.51 4.0 0 3.5 85.24 33.29 27.56 429.94 85.48 0.938

30% FASTIRON 93.90 93.90 4.4 0 3.5 87.00 35.81 30.02 283.34 91.97 0.935

30% FASTEEL 93.90 93.90 4.4 0 3.5 87.98 35.81 30.02 201.97 91.97 0.935

30% COREX 93.81 93.81 4.6 0 3.5 86.98 34.59 30.32 284.72 88.83 0.936

30% HIsmelt 95.47 95.47 4.0 0 3.5 86.67 28.30 25.47 310.67 69.50 0.945

100% Scrap 94.48 94.48 0.04 4 3.5 84.44 37.03 19.09 496.67 89.23 0.945

http://www.midrex.com/





Table IIa – BF/BOF Energy Data

Description US Data2

BF Pellet Sinter BF BOF/t pellet /t sinter /t hot metal /t liq. steel

Energy Input (MJ/t)

Metallurgical coal 0.0 0.0 0.0 0.0Metallurgical coke 0.0 1282.4 14555.7 0.0

Electrical power 652.2 342.4 243.7 255.9Utilities 0.0 0.0 1634.3 0.0Heavy Oil 976.3 0.0 1048.9 0.0Low Btu gas 0.0 47.5 0.0 8.2O2/N2 0.0 0.0 133.4 393.4

Non-coking coal 0.0 278.2 0.0 0.0Pulverized coal 0.0 0.0 2863.1 0.0Steam coal 0.0 0.0 0.0 0.0Limestone 0.0 0.0 0.0 0.0

Natural gas 0.0 13.9 111.3 365.6Metallic feed 0.0 0.0 0.0 2257.1

Sub-total (a) 1628.5 1964.4 20590.4 3280.1

Energy Output (MJ/t)

Coke for sale 0.0 0.0 0.0 0.0By-products for sale 0.0 0.0 0.0 0.0Metallic products 0.0 0.0 2536.0 0.0Electrical power for sale 0.0 0.0 0.0 0.0Utilities for sale 0.0 0.0 0.0 0.0Low Btu Gas for sale 0.0 0.0 5509.3 0.0

Sub-total (b) 0.0 0.0 8045.3 0.0

Sub-total Energy (a) - (b) 1628.5 1964.4 12545.1 3280.1

Total Energy (MJ/t) 16785.0Total Energy (kWh/t)Limestone kg/t 40.0 100.0 32.2 59.0

tons/t next processing step 1.073 0.449 0.890 1.000

Table IIb – BF/BOF Production Conditions

Operation Sequence Step Conditions

BF-BOF Pelletizing• Oil-fueled induration, fluxed or acid pellet, 64%

total iron

Sinter • Coal fueled sintering, fluxed sinter, 56% total iron

Blast Furnace • Coke + coal injection + oil/nat.gas add. + O2

enrichment, 4.0% C, 0.6% Si, 1500oC

BOF • 89% HM, 11% Scrap, 0.04% C, 1620oC



Production Processes

The following sections briefly describe the production processes chosen. The options considered fall into thefollowing groups:

• 80% AIU HM/20% scrap representative of economical integrated steelmaking practice

• 80% DRI/20% scrap representative of a captive DRI plant steelmaking practice• 50% AIU/50% scrap representative of maximum HM usage in EAF steelmaking

• 30% AIU/70% scrap representative of the minimum AIU use for high quality steel productionincluding 10% waste oxide AIU usage representing on-site auto-generation

• 100% scrap representing the EAF baseline

All of these are compared to 89% hot metal/11% scrap use in the BOF representing the BF/BOF baseline fromthe DOE report no. EE-022920 and from MIDREX computations.

The process combinations represent the desire for hot and cold high %C (high chemical energy) charges, aswell as cold “low” %C (conventional) charges. Carbon additions (both charge and foamy slag injected) to the

EAF reflect current steelmaking practices 6,8,9,10,15, thus allowing the impact of the higher %C AIUs to be felt onthe process. Charge C was added to heats to ensure a minimum O2 volume to reflect typical US practice ofapproximately 20 Nm3/tls. O2 usage has been allowed to “float” relative to the %C contained in eachsteelmaking system, in order to define the “least cost steelmaking” scenario 1. O2 values varied from 19.0 Nm3/t for 100% scrap to 43.3 Nm3/t for 50% COREX/ 50% scrap scenario. Table I outlines the blendedanalysis of the EAF feeds and the predicted thermal efficiency of melting, oxygen, and electrical energyrequired for steel production using a quaternary slag “V” ratio of 1.75.

In order to simplify the comparison between various charge mixes, high quality scrap charge mixes were used.It should be noted that with the 80% and 50% AIU mixes, it might be possible to opt for cheaper scrap mixes,which would lower the cost/t liquid steel.

Table III. Cost, Yield and Charge Make Up Assumptions for Scrap Charge

EAF CHARGE MIX $/Tonne %Phos %Sulf Yield EstScrap Charge Make-Up

20% 50% 70%

Heavy #1 $88.71 0.020% 0.040% 92.00% 0.00% 0.00% 0.00%

Heavy #2 $77.82 0.030% 0.070% 85.00% 0.00% 0.00% 0.00%

Heavy Prime $110.59 0.025% 0.025% 95.00% 0.00% 0.00% 0.00%

#1 Bushelling $113.58 0.010% 0.020% 95.00% 7.00% 19.00% 28.00%

Turnings $39.92 0.030% 0.080% 92.00% 0.00% 0.00% 0.00%

Shred $104.21 0.025% 0.040% 92.00% 0.00% 6.00% 8.00%

#1 Bundles $119.95 0.020% 0.025% 95.00% 7.00% 19.00% 28.00%

#2 Bundles $62.40 0.030% 0.090% 82.00% 0.00% 0.00% 0.00%Returns $123.00 0.020% 0.040% 98.00% 4.00% 4.00% 4.00%

Skulls $64.42 0.030% 0.080% 84.00% 2.00% 2.00% 2.00%

Municipal Shred $25.00 0.030% 0.090% 80.00% 0.00% 0.00% 0.00%

Pit Scrap $113.00 0.030% 0.080% 70.00% 0.00% 0.00% 0.00%

Note: The scrap yield for the 20%, 50% and 70% scrap charges varied from 94.445% to 94.555%. An average of 94.5%has been used as the global scrap yield for all charge mixes to calculate % gangue.



The combination of processes is not an exhaustive list of possible ironmaking/steelmaking combinationsavailable to the EAF operator, but the typical performance characteristics of each respective option is presented.The scope of processing incorporated into each of the production methods begins with the receipt of feedmetallics (iron ore and scrap), reductants (coal, natural gas, etc.), and energy (coal, natural gas and electricity)and ends with the tapping of a ladle of liquid steel (0.04% carbon and 1620°C) prior to any ladle furnace processing.

BF/BOF - The blast furnace information included was based on data covering the average of four highvolume, high technology (O2/fuel injection) BF operations in the US, reported in Iron & Steelmaker 2. TheBF/BOF information is based on an overall integrated energy balance covering coking, pelletizing, sinteringand BOF steelmaking, which was presented at the 2001 COM Conference 3. The BF operations from the USwere the basis for specific consumptions in the BF operations area. The energy balance for the BF/BOFoperations is shown in Table IIa. The conditions assumed in the BF/BOF operations for comparison with other production methods are indicated in Table IIb.

Since the original “green steelmaking” papers 3,4, a comparison between Midrex data and data from DOE publication EE-0229 5 has been performed to define any major difference in computations. There was closeagreement between the two sets of data except for the electrical power energy conversion. Midrex data

originally assumed 3,413 btu/kWh (net energy value for a kW of electrical power), while the DOE assumptionwas based on 10,500 btu/kWh (gross heat required to generate a kW of electrical power from coal). TheMidrex basis was changed to use 10,500 btu/kWh to be consistent with the DOE assumption. With this changeincorporated, the Midrex computations have been used as the basis for all production scenarios for liquid steelconsidered herein, and the energy balance format (Table IIa) was used. However, due to the volume of dataonly the summaries for each computational results for “total energy requirements” for each step and the“tons/ton next processing step” are given in Table IVa.

Details of the assumed production conditions for each production route, which allowed comparative analysisare summarized in Table IVb. Each data source for the production route is defined here below. Fulcomputational results are available at www.midrex.com

DEFINITION OF DATA SOURCES FOR PRODUCTION ROUTES

Results for “energy requirements per ton” for each step and the “total energy per ton liquid steel”, whichfactors in the feed ratios, are summarized in Table IVa. Details of the assumed production conditions for each production route, which allowed comparative analysis, are summarized in Table IVb.

80% FASTIRON HM/BOF (configuration known as FASTOx) –The production of FASTIRON, a liquid hotmetal product, uses the FASTMET RHF direct reduction technology and close-links the hearth with an EIF(electric ironmaking furnace) to produce hot metal, which is then charged to a conventional BOF. The

FASTIRON information is based upon an actual project quotation20

. The BOF data was gathered from BOFoperating data reported in Iron and Steelmaker and by DOE publication EE-0229 2,5.

80%, 50% and 30% hot or cold nominal C (2.5%) and high C (4%) DRI/EAF - The direct reductioninformation, using NG-based DRI, was gathered from material presented at the Midrex HBI/DRI MeltingSeminar 6 and data provided for the Midrex 2000 Operations Report 7, which gathers direct reduction plantsoperating data. The high C DRI data is based on operational experience of producing 3.5%C DRI 14, which has been extended to cover 4% C DRI production. This data applies equally to all the percentages CDRI and HDRused, at both the nominal (2.5%C) and high (4%C) carbon levels.





50% and 30% HBI/EAF – The hot briquetting information, using NG-based HBI, was gathered from material presented at the Midrex HBI/DRI Melting Seminar 6 and data provided for the Midrex 2000 Operations Report7, which gathers direct reduction plants’ operating data.

20% HBI + 30% PI/EAF – The hot briquetting information was gathered as specified above. The PIinformation is based on communications by Hornby-Anderson 8,9,15 with a steelmaker using high percentages of

pig iron, and the average data taken from four high production, high technology BF operations in the USreported in Iron & Steelmaker 2.

50% and 30% PP/EAF – The PP (“pig pellets”) refers to a new technology, ITmk3. Ore and coal fines are pelletized or cold briquetted and fed to an RHF, where the pellets/briquettes are reduced, and then proprietarytechnology is used to separate the gangue from the iron, producing iron nuggets. On discharge from the RHF,the gangue residue is separated from the nuggets, leaving pig iron quality iron nuggets (“pig pellets” [PP]) witha potential 3.0% to 4.0% C content. The ITmk3 information is based on data from the Kobe Steeldemonstration plant (KDP) and the scale-up for the Mesabi Nugget demonstration plant in Minnesota 21.

50% BF hot metal/EAF – the BF information is based on data covering the average of four high volume, high

technology (O2/fuel injection) BF operations in the US, reported in Iron & Steelmaker 2

. The BF/BOFinformation is based on an overall integrated energy balance covering coking, pelletizing, sintering, and BOFsteelmaking, presented at the 2001 COM Conference 3. BF operations from the US are the basis for specificconsumptions in the BF operations area.

50% and 30% FASTIRON + 50% and 70% cold scrap/EAF – The production of FASTIRON, a liquid hotmetal product, uses the FASTMET RHF direct reduction technology and close-links the hearth with an EIF (configuration known as FASTMELT) to produce hot metal (FASTIRON) and thereby, reduce the slagcompounds going to the EAF. The FASTIRON information is based on an actual project quotation to aEuropean steelmaker 20.

50% and 30% FASTIRON + 50% and 70% hot scrap/EAF (configuration known as FASTEEL ) – This isa new process merging FASTMELT and CONSTEEL® technologies. The result is an EAF with constant feedof FASTIRON Hot Metal (FI HM) and preheated scrap. The FASTIRON information is based on an actual project quotation to a European steelmaker 20.

50% and 30% HIsmelt HM/EAF – The HIsmelt Process reduces iron ore fines with coal and enriched hot air blast to produce HM. The HIsmelt information is based on a published paper by presented by Bates 18.

50% and 30% COREX HM/EAF – The COREX Process produces HM from reduced oxide pellets and/orlump ore and coal in a smelting furnace. The smelting furnace produces excess quantities of fuel rich off-gas,which is used to reduce the iron ore and optionally to produce power. The information is based on a VAI

publication19

.

50% and 30% HBI/EAF - The hot briquetting information, using NG-based HBI, was gathered from material presented at the Midrex HBI/DRI Melting Seminar 6 and data provided for the Midrex 2000 Operations Report7, whichgathers direct reduction plants’ operating data.

10% Waste Oxide FASTMET + 20% PI/EAF – The FASTMET waste oxide (FM(WO)) information is based on the two commercial FASTMET installations at KSL and Nippon Steel and proposals for FM(WO)recycling projects in the US12,13,16. The PI information is based on the average data taken from four high



production, high technology BF operations in the US reported in Iron and Steelmaker 2 and on privatediscussions with steelmakers melting PI 8,15.

Table IVa. Summary of Energy Data for all Steelmaking Options (kWh/t)

Energy for eachProcess Step& Total Energy per t liquid steel.* B F

P e l l e t

/ t

p e l l e t

D R

P e l l e t

/ t

p e l l e t

C B Q

/ t b r i q

C B P

/ t

p e l l e t

S

i n t e r

/ t

s i n t e r

B F

/ t H M / P I

C D R

I / H D R I

/ t D R I

H B I

/ t H B I

R H F

/ t D

R I / P P

E I F

/ t H M

S F

/ t H M

B O F

/ t l . s .

E A F

/ t l . s .

T o t

E n e r g y

K W h / t l . s

89% BF HMMTI

452 546 3485 911 4663

89% BF HMDOE

503 546 3397 911 4624

80%FI-FASTOx 80 2705 1321 892 4545

80% Cold DRI 529 2695 1949 5065

80% Hot DRI 529 2570 1634 4592

80% Hi C CDRI 529 2795 1956 5124

80% Hi C HDRI 529 2670 1633 4766

50% CDRI 529 2795 1907 3893

50% HBI 529 3341 1924 4204

20%HBI/30%PI 452 529 546 3857 3341 1606 4007

50% PP 511 4744 1516 4447

50% BF HM 452 546 3485 1003 3284

50% FASTIRON 80 2705 1321 980 3419

50%FI/H scrap(FASTEEL)

80 2705 1321 805 3243

50% COREX 452 5342 987 4217

50% HIsmelt 5310 1046 3856

30% CDRI 529 2695 1735 2901

30% Hi C CDRI 529 2795 1716 2891

30% Hi C HDRI 529 2670 1600 2734

30% HBI 529 3341 1817 3163

10% FM(WO)/20% PI

452 91 546 3857 2759 1631 2970

10% FM(WO)/20% PP

91 51127594744

1645 3174

30% CFM (O) 91 3750 1787 3092

30% HFM (O) 91 3550 1687 2926

30% PP (ITmk3) 511 4744 1541 3294

30% BF HM 452 546 3485 1520 3000

30% FASTIRON 80 2705 1321 1210 2662

30%FI/H ScrapFASTEEL)

80 2705 1321 973 2423

30% COREX 452 5342 1217 3140

30% HIsmelt 5310 1272 2957

100% Scrap 1647 1647

* Note: Total Energy per t liquid steel. requires feed ratio information from computational tables.



10% waste oxide FASTMET + 20% PP/EAF – The FASTMET waste oxide (FM(WO)) information is basedon the two commercial FASTMET installations at KSL and Nippon Steel and proposals for FM(WO) recycling projects in the US12,13,16. The PP (“pig pellets”) are produced by a new technology, ITmk3. Ore and coal finesare pelletized or cold briquetted and fed to an RHF, where the pellets/briquettes are reduced, and then proprietary technology is used to separate the gangue from the iron, producing iron nuggets. On discharge fromthe RHF, the gangue residue is separated from the nuggets, leaving pig iron quality iron nuggets (“pig pellets”[PP]) with a potential 3.0% to 4.0% C content. The ITmk3 information is based on data from the Kobe Steel

demonstration plant (KDP) and the scale-up for the Mesabi Nugget demonstration plant in Minnesota 21.

30% ore based cold and hot FASTMET/EAF – The ore-based FASTMET (FM(O)) information is based onthe two commercial FASTMET installations at KSL and Nippon Steel and FM proposals 13,16.

30% PI/EAF – The pig iron information is based on communication with a steelmaker by Hornby-Anderson8,15 using high percentages of pig iron, and the average data taken from four high production, high technologyBF operations in the US, reported in Iron & Steelmaker 2.

100% scrap/EAF - The scrap information is based on discussions with steelmakers by Hornby-Anderson 6,8,15

The information is being primarily presented to show the background scrap results, which are used in nearly all

of the case comparisons. For the purpose of this paper, scrap has been chosen to best represent high steel quality production to enable a better comparison with the AIU/EAF practices. In reality, 50% and 80% AIU mixecould use lower scrap qualities, which would change energy and greenhouse gas computations, making themhigher.

Table IVb. Summary of Operating Conditions for the Various Liquid Steel Production Scenarios


BF HM-BOF Pelletizing • Oil fueled induration, fluxed or acid pellet, 64% total iron


Blast Furnace• Coke + coal injection + oil/nat.gas add. + O2 enrichment, 4.0% C,

0.6% Si, 1500°C

BOF• 89% HM, 11% Scrap, 0 kg added carbon, 56.80 Nm3/t oxygen,

0.04% C, 1620°C80% FASTIRON-BOF (FASTOx)

Cold Briquetting • Coal reductant, organic binders

Direct Reduction • NG-fueled, RHF, 1000°C

EIF® • AC furnace, 4.4% C, 0.8 Si, 1500°C

BOF• 80% HM, 20% Scrap, 0 kg added carbon, 59.28 Nm3/t oxygen,

0.04% C, 1620°C

CDRI/HDRI-EAFPelletizing • NG-fueled induration, DR pellet, 67% total Fe

Direct Reduction• CDRI NG-based, shaft furnace, 2.5% carbon

• HDRI NG-based, shaft furnace, 2.5% carbon, 700oC




EAF

• All 3.5kg/t foamy slag C; 0.04%C, 1620o

• 80% CDRI/HDRI, 20% Scrap, 0 kg charge carbon, 22.27 Nm3/toxygen

• 50% CDRI, 50% Scrap, 2.0 kg charge carbon, 22.05 Nm3/toxygen

• 30% CDRI, 70% Scrap, 3.0 kg charge carbon, 21.22 Nm3/toxygen

Hi C CDRI/HDRI-EAF

Pelletizing • NG-fueled induration, DR pellet, 67% total Fe

Direct Reduction• CDRI NG-based, shaft furnace, 4.0% C

• HDRI NG-based, shaft furnace, 4.0% C, 700oC

EAF

• All 3.5kg/t foamy slag C; 0.04%C; 1620oC

• 80% Hi C CDRI/HDRI, 20% Scrap, 0 kg charge carbon,38.80Nm3/t O2

• 30% Hi C CDRI/HDRI, 70% scrap, 0 kg charge carbon,21.00Nm3/t O2

HBI-EAFPelletizing • NG-fueled induration, DR pellet, 67% total Fe

Direct Reduction • NG-based, shaft furnace, 1.5% C

EAF• All 3.5kg/t foamy slag C; 0.04%C, 1620oC

• 50% HBI, 50% Scrap, 5.0 kg charge carbon, 19.68 Nm3/t O2

• 30% HBI, 70% Scrap, 5.0 kg charge carbon, 20.22 Nm3/t O2

20% HBI +30% PI-EAF

Pelletizing • Oil fueled induration, fluxed or acid BF pellet, 64% total Fe

Sinter • Coal fueled sintering, fluxed sinter, 56% total Fe

Blast Furnace• Coke + coal injection + oil/NG add. + O2 enrichment, 4.0%

carbon, 0.6% silicon

Pelletizing •

NG-fueled induration, DR pellet, 67% total Fe

Direct Reduction • NG-based, shaft furnace, 1.5% C

EAF• 3.5kg/t foamy slag C; 0.04%C; 1620oC

• 20% HBI, 30% PI, 50% Scrap, 0 kg charge carbon, 28.59 Nm 3/tO2

ITmk3 (PP)-EAFPelletizing/Cold

briquetting• Coal reductant, organic binders

Direct Reduction • NG-fueled RHF, 3.5% C

EAF

• All 3.5 kg/t foamy slag C, 0.04% C, 1620°C

• 50% PP, 50% Scrap, 0 kg charge carbon, 33.86 Nm3/t O2

• 30% PP, 70% scrap, 0 kg charge carbon, 24.74 Nm3

/t O2

50% BF HM-EAF Pelletizing • Oil fueled induration, fluxed or acid BF pellet, 64% total Fe



carbon, 0.6% silicon, 1500°C

EAF• 50% HM, 50% Scrap, 3.5 kg/t foamy slag C, 0 kg charge carbon,

38.65 Nm3/t O2 0.04% carbon, 1620°C




FASTIRON-EAF Cold Briquetting • Coal reductant, organic binders

Direct Reduction • Natural gas-fueled, rotary hearth furnace, 1000°C

EIF® • AC furnace, 4.4% carbon, 0.8% Si, 1500°C

EAF• All 3.5 kg/t foamy slag C, 0.04% carbon, 1620°C

• 50% FI HM, 50% Cold Scrap, 0 kg charge carbon, 42.84 Nm 3/t O2

• 30% FI HM, 70% Cold Scrap, 0 kg charge carbon, 30.02 Nm 3/t O2

FASTIRON-EAFw/Scrap Preheat(FASTEEL™)


Direct Reduction • Natural gas-fueled, rotary hearth furnace, 1000°C

EIF® • AC furnace, 4.4% carbon, 0.8% Si, 1500°C

EAF

• Scrap preheated to 600oC

• All 3.5 kg/t foamy slag C, 0.04% carbon, 1620°C

• 50% FI HM, 50% Hot Scrap, 0 kg charge carbon, 42.84 Nm 3/t O2

• 30% FI HM, 70% Hot Scrap, 0 kg charge carbon, 30.02 Nm 3/t O2

COREX-EAF Pelletizing • Oil fueled induration, acid BF pellet, 64% total iron

Smelting Furnace• BF grade pellets, Coal and O2 for smelt reduction, HM at 4.5%

C, 0.7% Si, 1500°C. 13.2 GJ/t off gas credit.

EAF• All 3.5 kg/t foamy slag C, 0.04% carbon, 1620°C

• 50% HM, 50% Scrap, 0 kg charge carbon, 43.33 Nm3/t O2

• 30% HM, 70% Scrap, 0 kg charge carbon, 30.32 Nm3/t O2

HIsmelt-EAF Smelting Furnace• Iron ore fines, Coal, 30% O2 enriched hot blast, HM at 4% C,

0.2% Si, 1500°C. “Power Balanced Flowsheet” All electrical & O2

power is produced from off gas.

EAF• All 3.5 kg/t foamy slag C, 0.04% C, 1620°C

• 50% HIS HM, 50% Scrap, 0 kg charge carbon, 35.02 Nm 3/t O2

• 30% HIS HM, 50% Scrap, 0 kg charge carbon, 25.47 Nm 3/t O2

10% FM(WO)+20% PI-EAF

Pelletizing • Oil fueled induration, fluxed or acid BF pellet, 64% total Fe



carbon, 0.6% silicon


Direct Reduction • NG-fueled, RHF, 2.5% C, 1000°C

EAF•

10% FM(WO) DRI, 20% PI, 70% Scrap, 3.5 kg/t foamy slag C, 0kg charge carbon, 26.68 Nm3/t O2, 0.04% C, 1620°C10% FM(WO)+20% PP-EAF

Pelletizing/Cold briquetting

• Coal reductant, organic binders

Direct Reduction • NG-fueled RHF, 3.5% C


Direct Reduction • NG-fueled, RHF, 1000°C, 2.5% C




EAF• 10% FM(WO) DRI, 20% PP, 70% Scrap, 3.5 kg/t foamy slag C, 0

kg charge carbon, 24.74 Nm3/t O2, 0.04% C, 1620°C

30%CFM(O)/HFM(O)-

EAFCold Briquetting • Coal reductant, organic binders

Direct Reduction • CFM NG-fueled, RHF, 2.5%C• HFM NG-fueled, RHF, 2.5%C, 1000°C

EAF

• All 3.5 kg/t foamy slag C, 0.04% C, 1620°C

• 30% CFM(O) DRI, 70% Scrap, 2.0 kg charge carbon, 22.15 Nm3/tO2

• 30% HFM(O) DRI, 70% Scrap, 2.0 kg charge carbon, 22.15 Nm3/tO2

30% Pig Iron-EAF Pelletizing • Oil-fueled induration, acid pellet, 64% total Fe pellet


Blast Furnace• Coke +coal injection +oil/NG add.+O2 enrichment, 4.0% carbon,

0.6% silicon

EAF• 30% PI, 70% Scrap, 3.5 kg/t foamy slag C, 0 kg charge carbon,

27.56 Nm3/t O2, 0.04% carbon, 1620°C

Scrap-EAF EAF• 100% Scrap, 3.5 kg/t foamy slag C, 4.0 kg charge carbon, 19.09

Nm3/t O2, 0.04% carbon, 1620°C

RESULTS

Energy & Emissions

Figures 1, 2, and 3 summarize the results of the energy and emissions evaluation for the production methodsassessed. The graph includes the total energy required to produce the liquid steel, energy for conversion fromiron to steel (BOF or EAF energy inputs), and the carbon dioxide emissions generated throughout the production process. The units of energy are given in kWh/t of liquid steel, and the emissions are given in kg-CO2/t liquid steel. Due to the number of cases studied, the results are divided into three graphs which representhe 80% AIU, 50% AIU and 30%AIU usage, respectively.

In order to highlight the significant impact of feed materials on the EAF energy balance, the conversionenergy line has been expanded by using the same scale as for the CO2 emissions.



Figure 1 – Total Energy, EAF Energy and CO2 Emissions (80% AIU)


AI-EAF Comparison

4

7 6 5 5

1 2 4

4 5 9

2

5 0 6 5

1 6 4 7

4 5 4 5

4 6

6 2

4 6 2

4

1 9 2 2

1 9 5 9

1 4 6 7

4

4 1

1 1 6 3

1 0 6 5 1

1 9 5

1 0 6 6

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

BF-BOF

(DOE)

BF-BOF

(Midrex)

FASTMELT-

BOF

100% SCRAP 80% CDRI 80% HDRI 80% HI C

CDRI

80% HI C

HDRI

k W h / t L S ( T o t a l E n e r g y )

0

500

1000

1500

2000

2500

3000

k W h / t L S ( E A F E n e r g y ) , k g C O 2 / t L S ( C O 2 E m i s s i o

n s )

Total Energy

EAF Energy

CO2 Emissions

AI-EAF Comparison

3 4 1 9

3 2 4 3

3 8 8 7

3 3 0 0

4 2 1 7

4 4 3 5

4 0 1 7

4 2 0 7

3 8 9 3

1 6 4 7

4 5 4 5

4 6 6 2

4 6 2 4

1 9 2 2

1 9 5 9

1 4 6 7

4 4 1

9 1 2

9 9 1

1 3 2 0

1 1 9 8

1 5 0 7

1 0 8 5

1 0 4 1

1 8 8 0

1 2 5 9

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

B F - B O F

( D O E

)

B F - B O F

( M i d r

e x )

F A S T M E

L T - B O F

1 0 0 %

S C R

A P

5 0 % H

I C C D R

I

5 0 % H

B I

2 0 % H

B I + 3

0 % P I

5 0 % I T

M K 3

5 0 % B

F H M

5 0 % F A

S T I R

O N

5 0 % F A

S T E E

L

5 0 % C

O R E X

5 0 %

H I S M E

L T


0

500

1000

1500

2000

2500

3000

k W h / t L S ( E A F E n e r g y ) , k g C O 2 / t L S ( C O 2 E m i s s i o

n s )

Total Energy

EAF Energy

CO2 Emissions




The results of this study indicate that:

• For a 80% iron ore-based steelmaking facility, DRI consumes slightly more overall energy but producessignificantly less carbon emissions than the BF/BOF technology because of its use of natural gas for ironore reduction.

• The EAF production routes, which utilize greater amounts of scrap, have lower total energy and carbon

emissions than the conventional BF/BOF route.• To minimize total energy consumption and CO2 emissions, scrap use must be maximized.

• Since many steel products cannot be made with a 100% scrap feed, a portion of alternative iron ischarged to the EAF to meet quality requirements.

• As the amount of AIUs charged to the EAF increases, so do the total energy consumptions and CO 2

emissions.

• AIUs produced by natural gas-based reduction (DRI & HBI) promote lower total energy consumptionsand significantly less CO2 emissions than (cold) pig iron.

• In the 80% AIU group, Hi C HDRI & HDRI have lower CO 2 and EAF energy, and compare equally fortotal energy with the BF-BOF route.

• In the 50% AIU group, FASTIRON, FASTEEL, and BF HM have the lowest total energy and EAF

energy, while BF HM and COREX have the highest CO2 emissions.

• In the 30% AIU group, FASTEEL has the lowest Total energy and EAF energy, followed byFASTIRON. The highest CO2 emissions from the group fall to the PI and COREX scenarios.

• All of the HM scenarios have the lowest EAF energy for any given group.

• EAF operations need to consider the global picture rather than operate in isolation.

AI-EAF Comparison

2 9 7 2

3 1 7 4

3 0 9 2

2 9 2 6 3

2 9 4

2 6 6 2

2 4 1 0

2 9 5 7

3 0 0 3

3 1 6 3

2 7 3 4

2 8 9 1

2 9 0 1

1 6 4 7

4 5

4 5

4

6 6 2

4

6 2 4

3 1 4 0

1 9 2 2

1 9 5 9

1 4 6 7

4 4 1

9 9 7

8 2 6

8 5 2

8 1 1

8 7 6

1 1 6 5

8 1 1

7 4 9

1 2 8 6

9 1 8 7

0 2

6 9 3

6 3 2 7

6 6

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

B F - B O F ( D

O E )

B F - B O F

( M i d

r e x )

F A S T M E

L T - B O

F

1 0 0 %

S C R A

P

3 0 % C

D R I

3 0 % H

I C C

D R I

3 0 % H

I C H

D R I

3 0 % H B I

1 0 % F M

( W O ) + 2 0

% P I

1 0 % F M

( W O ) + 2

0 % I T M K

3

3 0 % C F M

( O )

3 0 % H F M

( O )

3 0 % I T

M K 3

3 0 % P

I

3 0 % F A

S T I R O

N

3 0 % F A S T

E E L

3 0 % C O

R E X

3 0 % H I S M

E L T


0

500

1000

1500

2000

2500

3000

k W h / t L S ( E A F E n e r g y ) , k g C O 2 / t L S ( C O 2 E m i s s i o n s )

Total Energy

EAF Energy

CO2 Emissions



SUMMARY

The most greenhouse gas and energy friendly steelmaking process is EAF melting of 100% scrap. As this practice is not conducive to high quality steelmaking, AIUs must be used. NG-based reduction maintains it position as the minimum CO2 route, but availability and cost of NG make this option unattractive in manyregions. Coal-based reduction, with hot metal charging to the EAF, offers the next best option by reducing totaand EAF energy and only slightly increasing CO2 emissions over the NG scenarios.

FASTEEL, incorporating both coal-based reduction, hot metal, and preheated scrap charging to the EAF,might present the best picture of future steelmaking.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the kind support of Midrex Technologies, Inc., Kobe Steel Ltd.MIDREX Process Licensees, and contributing steelmakers for providing their operating data to enable thecontinued improvement in steelmaking operations.



REFERENCES

1. S.A. Hornby Anderson, G.E. Metius, R.L. Hunter, “Influence of AIS Chemistry on EAF SteelmakingEconomics”, to be presented at the Electric Furnace Conference, San Antonio, TX Nov 10-13, 2002, Ironand Steel Society

2. “2000 Blast Furnace Roundup”, Iron & Steelmaker, Vol. 27, No. 8, August, 20003. S. Hornby-Anderson, J. Kopfle, G. Metius and M. Shimizu, “Green Steelmaking with the MIDREX® and

FASTMET® Processes”, Paper presented at COM: The Conference of Metallurgists “Greenhouse Gases inthe Metallurgical Industries: Policies, Abatement, and Treatment“, Toronto, Canada, August 26-29, 2001

4. J.M. McClelland, G.E. Metius, S.A. Hornby Anderson, “Future Green Steelmaking”, 32nd SEAISIConference Proceedings, Tokyo, Japan, April 2002

5. “Energy and Environmental Profile of the U.S. Iron and Steel Industry”, DOE report no EE-0229, August2000

6. Plant data submitted for Midrex Melting Seminar, May, 2000, Tuscaloosa, AL, USA7. Plant data submitted for Midrex Operations Report, January, 2000, Unpublished8. S. Hornby-Anderson, Private Communications, Midrex Technologies, Inc., March, 20019. Midrex Technologies Inc./BHP, “HBI & DRI Melting Seminar”, held in conjunction with 30th SEAISI

Conference, Singapore, May 2001

10. S.A. Hornby Anderson, “Educated Use of DRI/HBI Improves EAF Energy Efficiency and Yield andDownstream Operating Results”, European Electric Steelmaking Congress proceedings, Venice, Italy, May26-29, 2002

11. G. E. Hoffman, “FASTMELT - The Preferred Choice”, Paper presented at the Gorham Conference“Beyond the Blast Furnace”, Atlanta, GA, USA, 7 June 2000

12. J. M. McClelland, Private Communications addressing waste oxide recycling at a North American steelmill, October 2000

13. J. M. McClelland, “Proven FASTMET® Process: Right for India”, The Indian Institute of Metals and TataSteel’s Conference “Direct Reduction and Direct Smelting”, Jamshedpur, India, Oct. 5th – 6th, 2001

14. G. Metius, Authors personal experience, April 1990, and subsequent technology developments.15. S.A. Hornby Anderson, Private Communications with MIDREX Licensees’ steelmills

16. J. M. McClelland, Private Communications, Midrex Technologies, Inc., March, 200117. S. Montague, “HOTLINK™ - Hot Charging DRI for Lower Cost and Higher Productivity”, ISS 57th

Electric Furnace Conference Proceedings, Pittsburgh, PA, USA, Nov. 14-16, 199918. Peter Bates and Andrew Coad, “HIsmelt, The Future In Ironmaking Technology”, 4th European Coke &

Ironmaking Conference, Paris, June 200019. VAI publication, “The COREX® C-3000 Generation”20. Kobe Steel Proposal for FASTIRON facility at a European Steelmill21. Estimated consumptions from design calculations for Mesabi Nugget Project, to be verified during

demonstration plant operation.



APPENDIX A

Energy & Carbon Conversion Factors

The conversion factors used in the paper, shown below, are based on continental US operating conditions

Conversion Factors

Item to Convert Factor

Electricity to energy & carbon

2646 kcal/kWh*, 0.208 kg-C/kWh for composite grid power**0.281 kg-C/kWh for coal generated power

Natural gas to energy & carbon 9,518 kcal/Nm3, 0.065 kg-C/Mcal

Coke to energy & carbon 7,149 kcal/kg, 0.122 kg-C/Mcal

Coal to energy & carbon 7,492 kcal/kg, 0.106 kg-C/Mcal

Coke to coal equivalent 1.0 kcal coke : 1.3 kcal coalFuel oil to energy & carbon 9,801 kcal/kg, 0.087 kg-C/Mcal

Oxygen to electricity 1.2 kWh/Nm3

Limestone to carbon 0.12 kg-C/kg

* Equivalent Thermal Energy required to generate delivered electricity 15

** Calculated from “Electrical Power Annual 2000 – Volume 1”, Energy InformationAdministration2

green steel making

Documents