Pollution Prevention in the Steel IndustryToward a Zero Waste Plant

Leonard M. Wrona, P.E., Hatch Associates Consultants, Inc., Buffalo, New York

and Gillian Julien, Ph.D., P. Eng., Hatch Associates Ltd., Mississauga, Ontario

ABSTRACT

The American steel industry has made tremendous efforts in the past decade to drasticallyreduce its operating costs and to comply with environmental requirements. Given thissituation, the promotion and acceptance of a "zero waste" philosophy in environmentalcircles may appear to be an unwelcome challenge for the industry, involving more up frontexploratory work than continued operation with a pollution control/compliance philosophy.

We believe that there are some key areas with significant economic and environmentalimplications where evaluation of zero waste alternatives would make good business senseto steel company Board of Directors.

This paper outlines how the "zero waste" concept could be reflected in a North Americansteel mill's operating reality. It defines the concept of "zero waste" and discusses thetrends driving the acceptance of this philosophy. Key process areas with unresolvedwaste problems are identified and some zero waste alternatives are suggested forresolving them. It highlights the incentives for implementing a "zero waste" operatingphilosophy. An approach to zero waste program development and implementation isdescribed.

INTRODUCTION

The North American steel industry spends on average $12 per ton on operating costs to meet itsenvironmental compliance obligations. Improving collection and treatment efficiencies andattempting to lobby and legislate away environmental regulatory obligations is not a viable longterm alternative for reducing these costs. The current trend across many industries is to re-evaluate the manufacturing process with a view to reducing emissions and process waste by fullyutilizing all resources. Waste minimization strategies for the steel industry have the potential toprovide savings of $5 per ton or more on compliance and waste disposal costs.

Reducing the cost of environmental compliance using a zero waste approach requires a shift inperspective from viewing environmental emissions and process waste as an unavoidable cost toviewing them as a possible source of revenue. In this paper, we define a concept of zero wastewhich is more comprehensive than the concepts encapsulated in regulatory or industry specificdefinitions of "pollution prevention", "source reduction" and "multi-media pollution prevention," theterms used by USEPA and other regulatory agencies to refer to methods of reducing

environmental emissions at the source. The trends driving the acceptance of this broaderphilosophy are discussed. Key steel manufacturing areas that have unresolved waste problemsare identified and suggestions provided with respect to zero waste alternatives. A methodology isgiven for implementation, including economic incentives for reducing waste in all aspects of thesteel plant.

THE ZERO WASTE CONCEPT

Our view of process waste minimization, "zero waste", is that it should be a structured approach tominimizing energy consumption, air emissions, effluent emissions, toxic _nd non-toxic wastegenerated either directly or indirectly by a manufacturing process. The zero waste approachutilizes three methods to accomplish its goal._- Reduce the volume of wastesat the sourcethroughimprovementsin process, operation,and

maintenance. For example, continuous charging technologies for electric arc furnaces reducethe volume of dust discharged by as much as 40%. Scrap in the preheater traps the dust andreturns it to the furnace, thereby increasing steel yield.

_- Convertprocesswastesto a useableproductforsome otherprocess. For example, the valueof EAF steelmaking slag is greatly increased if it is modified for use in cement-makingoperations.Redesignor develop a process whichproducesno unusablebyproducts. For example, theCOREX ironmaking process eliminates the need for cokemaking and coke oven gas byproductrecovery plants.

The "zero waste" approach is being adopted by many of our clients in the ferrous, non-ferrous andmineral processing industries. It acknowledges that the reduction, recycling and recovery ofwastes discharged by a production process is good for a business' bottom line as well as thesurrounding community's well-being

INCENTIVES FOR ADOPTING A ZERO WASTE PHILOSOPHY

U.S. environmental regulations drive the development of pollution prevention strategies acrossmany industries. In recent years, increasing public political and financial pressure andenvironmental compliance costs have spurred much greater activity in this area. Some recentchanges in regulation and perspective in these areas are described in the following paragraphs.

Environmental Regulations

Current initiatives clearly indicate the government's continL_edcommitment to the pollutionprevention philosophy. The 1984 Hazardous and Solid Wastes Amendments to the ResourceConservation and Recovery Act (RCRA) formalized the US federal government's preference forpollution preventionrather than pollution control. Although the Amendments apply only to toxicchemicals, success with the pollution-prevention concept has led EPA to promote the multi-mediapollution-prevention policy with all regulations. The 1990 Pollution Prevention Act crossed mediaboundaries to establish source reduction as the preferred method of environmental control. TheGreat Lakes Water Quality Standards (GLWQS) would set such low toxic limits that many plantswould be required to approach "zero discharge" for their water systems. Some version of the

GLWQS will probably be enacted by the states if not the Federal government. USEPA is currentlyreviewing effluent guidelines for the steel industry, and even without the GLWQS, steel industryeffluent limitations are likely to be reduced substantially.

EPA's effort to redefine hazardous waste through the Hazardous Waste Identification Rule isaimed at increasing metals recovery and recycling, not only within a plant but also betweenindustry sectors. Under one proposal, steel industry wastes sent off site for recovery of valuableconstituents would be treated as recycled products rather than as solid waste. If implemented, thisproposal would remove many regulatory impediments to resource recovery.

USEPA programs such as the Common Sense Initiative, the 33/50 program and the EmissionsReduction Trading program indicate a willingness to cooperate with industry to incorporate asmuch flexibility and creativity in dealing with environmental issues as possible. The emissionstrading concept allows demonstrated emissions reductions to be traded as a commodity betweencompanies or publicly. The U.S. program is currently applicable only to electric power plants,however it is expected this program will be extended to industry in the near future. In Canada, theprovince of Ontario is instituting a pilot emissions reduction trading program that includes all majorindustries. All these initiatives have been welcomed by the North American steel industry.

Public Pressure

The general public and environmental groups have become increasingly active politically andeconomically regarding environmental issues during the past decade. Increased access toinformation on a company's environmental performance through SARA Title III and Title V of theClean Air Act Amendments provides the public with knowledge that can be effectively used topressure companies to improve their environmental performance. To avoid the nuisance andexpense of citizen suits companies must go beyond compliance to remain "good neighbors."

"Socially responsible" mutual funds such as the Calvert Social Growth Fund, Neuburger andBerman's Socially Responsive Fund and the Domini Social Equity Fund are encouraging "GreenInvesting." A good corporate environmental record, recycling programs, energy conservation andagreement with the Coalition for Environmentally Responsible Economies (CERES) Principles areall viewed positively by these funds. Such funds do not purchase the stock of EPA violators orcompanies with poor environmental records. Financial institutions also closely scrutinize acompany's environmental performance before providing capital for expansion or processimprovements, since they would have significant risk exposure with respect to futureenvironmental clean-up costs.

Financial Incentives

In the face of increased global competition and increasingly stringent environmental regulations,the North American steel industry has closed old, inefficient and costly plants, sometimes replacingthem with new technology, as part of its efforts to maintain cost competitiveness. The cost ofbringing these plants into environmental compliance assured that closure was the onlyeconomically viable option. Cokemaking is a prime example of this dynamic. Compliance with the1990 Clean Air Act Amendments requires significant investment in repairs and upgrading of oldfacilities, and the discipline to follow strict operating and maintenance practices. Although manyintegrated and merchant coke producers made the required investment in their cokemaking

facilities in the 1990s, other plants were shut down, in part due to environmental costs. Capitalcosts for new coke ovens, material handling and byproducts plants may range from $200 to $350per ton of coke.

Figure 1 shows the average operating cost in dollars per ton for environmental compliance in theU.S. from 1988 to 1994. The steel industry spends an average of $12 per ton in operating costs tooperate and maintain pollution control equipment. Capital costs for environmental controls totaled$231 million in 1994. Increasingly stringent regulatory restrictions ensure that the costs ofcollecting, treating and disposing of wastes will continue to rise. Waste minimization strategies forthe steel industry have the potential to provide savings of $1 to $5 per ton or more on complianceand waste disposal costs.

POTENTIAL ZERO WASTE PROCESSES FOR THE STEEL INDUSTRY

It is neither reasonable nor economical to attempt to make every process within a steel plant into azero waste process, since the thermodynamics and kinetics of some reactions mitigate againstachieving absolute zero waste. The key is to choose those areas with the greatest potential tomake an immediate environmental and economic impact. We believe that the cokemaking, DRIproduction, steelmaking and hot rolling areas hold the greatest potential for economic wasteminimization. Some suggestions for zero waste approaches and technologies in these areas areprovided below. A value for potential savings in environmental costs cannot be provided, since theeconomics for every plant is uniquely determined by its location, age, product mix, equipment, coststructure among other factors.

Cokemaking

Coke oven gas by-product recovery processes continue to pose problems in two areas:•"- Benzene emissions from tar decanters, dehydrators and the light oil recovery process.

Extensive multi-stage water treatment processes consume energy and resources and may notprovide sludges suitable for re-use in coke ovens.

For these reasons, byproducts plants provide excellent opportunities for zero waste initiatives.Integrated and merchant coke producers in operation after 1991 installed gas-tight emissionscollector headers in the byproducts recovery plant. These new systems assure negative pressurein the system to eliminate leaks and use a "sweep" gas to maintain flow. At Acme Steel, theseimprovements prevented the loss of 14,000 pounds per year of benzene as Well as smalleramounts of toluene and xylene, which are now sold as byproducts.1 Waste can often beminimized by tightening up the operation and maintenance of existing processes. Nonetheless,the cost of treatment to meet compliance standards has contributed to the closure of manycokemaking facilities.

Another zero waste option in this area is to develop new coking processes that reduce emissionsat the source. The Jewell and Kembla non-recovery cokemaking processes are technically viablefor a narrow range of coals. These existing processes eliminate the need for a traditional by-product recovery plant and associated emissions of hazardous air and water pollutants. However,SO2 emissions have been significantly greater than traditional coke plants. Continued effort toincrease the quality of coals that can be processed may take 5 to 15 years but is worth pursuing.Other sealed coke manufacturing processes such as the European "Jumbo Coking Reactor"2 and

the American Calderon Coking 3 process currently under development may nearly eliminate allcoke oven emissions, approaching a true zero waste process.

The COREX ironmaking technology could be truly a zero waste approach if the excess fuel gasgenerated can be usefully harnessed. The COREX process produces approximately 20% of theemissions of comparable blast furnace and coke ovens. A 715,000 ton capacity unit will generate5.3 million cubic feet per hour of high BTU content gas. This excess fuel could be used to operatea Non-Utility Generator (NUG). The Indian steel company, Jindal Steel, will build and operate a 95MW electric generation facility in conjunction with its 1.5 million tpy COREX plant. Thecombination of COREX and a NUG is a reasonable option in areas with an inadequate powersupply grid.

DRI Production

The rapid growth in electric arc furnace steelmaking in the U.S. and the anticipated difficulties inobtaining low residual scrap have made DRI a very attractive raw material for use in EAFsteelmaking. The production of DRI is not without its unresolved waste problems, however. Ironoxide fines generated during the screening of ore and pellets are a process waste for which thereis no current economic use. Many DRI plants buy pellets and it is not economical to return fines tothe pelletizing plants that supply their raw materials. A pelletizing plant could recycle oxide,metallized fines, and some scrubber sludges, but iron ore fines are usually stockpiled for eventualreclaiming. The volume of fines can be reduced if the plant is fed pellets rather than lump ore.

A DRI technology that uses iron ore fines is a zero waste complement to the two DRI technologieswidely used. There are several processes for the production of direct reduced iron or thetreatment of iron bearing wastes which use iron oxide fines as raw material:

The DIOS coal based process (Japan) uses iron ore fines, which are pre-reduced in a fluidizedbed, to produce liquid iron from a bath smelting reduction process.The FIOR natural gas based process (Venezuela) uses 100% fines in a multiple stationaryfluidized bed.

The Lurgi Circofer (coal based) and Circored (hydrogen based) processes use iron ore fines toproduce DRI.

One option which produces a true zero-waste process is a combination COREX and DRI plant.The excess fuel generated by a COREX plant is sufficient to produce DRI at 60% or more of thehot metal volume. In addition, the oxide and metallized iron fines generated in the DRI plant couldbe fed to the COREX melter gasifier. Hanbo Steel's Dang Jim plant in Korea will use the off-gasfrom two COREX C-200 plants to operate a Midrex DRI facility and generate 200 MW ofelectricity. 4

Steelmaking Slags

Steelmaking slags have fewer applications than blast furnace slags, and presently the industry isstockpiling BOF slag at a rate of approximately 4 million tons per year. In the U.S., BOF slag maybe used as aggregate for road construction after it has been screened and treated to remove themetallics. Recently in Canada, the Province of Ontario placed a moratorium on the use of allsteelmaking slags for road construction after experiencing significant problems in pavement

performance. EAF slags are typically landfilled since their free lime content makes the productunsuitable for road construction.

Opportunities for waste minimization include the reduction of slag volume through better control oflime input to the furnace and improved control of silicon and sulphur in blast furnace hot metal.Steelmaking slags could also be reformulated for use in areas currently served by blast furnaceslags. In 1994, 13.5 million tons of blast furnace slags were sold for the manufacture of cement,road base, railroad ballast, light weight concrete block, glass and artificial rock.

Evaluation of slag reuse is a low cost, high value option for steel plants. The technology forreducing slag volume and increasing its value to other industries exists. It is dependent more onsteelmaking chemistry and operating practices than on capital investment.

ROF Steelmaking Dust and Sludge

Dust and sludge from BOF steelmaking shops pose a reuse and recycling problem since there arecurrently no alternate uses for this material. The rising cost of scrap and waste disposal, scarceon-site landfill space, and potential future environmental liabilities provide economic incentive torecover iron units from dust and sludge. Recycling it to the blast furnace may raise the hot metalphosphorus content to undesirable levels. The increasing use of galvanized scrap could increasedust and sludge zinc content such that the material would be regulated by EPA. The zinc maybuild up on linings, interfering with gas flow to the furnace. Typically zinc oxide levels in BOF dustand sludge range from 0.5 to 2%; it may be as high as 8% at some plants.

The zero waste approach for this area has two elements; minimization of the amount of dustdischarged in the off-gas and recycling the dust back into upstream processes. Scrapmanagement, the use of alternative sources of iron units or black scrap ensures that the zinc oxidecontent of dust and sludge remains low. This waste could be used as a low-cost scrap substitute ifcold-briquetted or cemented and ground. USS/Kobe avoids the use of galvanized scrap in itsoperation, thus permitting the recycling of BOF filter cake to its blast furnace and BOF, along withother waste oxides. Metal Recovery Technologies, Inc. (MRTI) recently began operating a facilityin East Chicago, Indiana, to remove zinc from scrap, s The process, developed in conjunction withthe AISI and U.S. Department of Energy, generates high-quality black scrap and 99.8% pure zinc,while removing zinc from the BOF waste stream.

Electric Arc Furnace Dust

EAF dust has long been a source of environmental concern for electric furnace operators.Baghouse dust from electric arc furnace melt shops is classified as a hazardous waste in NorthAmerica, Europe and Japan. Historically only the Waelz Kiln process has been a viable method ofrecovering zinc from large volumes of EAF dust. Hydrometallurgical processes such as the MRTprocess and Ezinex are recent exceptions, since they recover high quality zinc at reasonableoperating costs. Waelz kiln dust treatment costs range from $3 to $5 per ton of steel in the US.,based on dust zinc content. Landfilling of EAF dust stabilized by the Super Detox process isallowed in the U.S. under a 1995 USEPA ruling. However, stabilized dust does not recover anyvaluable constituents and increases the volume of waste going to landfill sites.

A zero waste approach worth investigating is the reduction of dust generated in the steelmakingprocess combined with methods of reducing the volume of dust to be captured by the baghouse.A joint project by the Center for Material Production and Steel Manufacturer's Association isstudying methods of reducing the volume of dust generated during EAF steelmaking.

Continuous scrap charging/preheating technologies, such as the Consteel process, reduce dustdischarged from the furnace by two methods. Firstly, the system eliminates a backcharge and inmost cases the initial charge, thereby eliminating the large plume of dust and fumes producedduring those operations. Charging is the most difficult fume control problem and the size of thecharging plume normally sets the fume control system capacity. By reducing or eliminating theneed for charging, these processes reduce overall air pollution control costs. Secondly, theincoming scrap traps the dust generated in the furnace as the furnace off gas contacts it. Thescrap acts as a filter to capture dust and return it to the furnace, thereby reducing the volume ofdust discharged to the baghouse.

New EAF dust treatment processes such as All-Met, Horsehead Resources Development's TotalRecycle process and Phillip Environmental's IBRD-ZIP process seek to recover both zinc and iron,and are designed to produce minimal by-products, making them virtually zero waste.

Hot Rolling

The hot rolling operation generates scales and sludges with high iron content, contaminated withsignificant amounts of oil and grease. A hot strip mill could generate as much as 50 tons per dayof scale and sludge with oil content ranging from 1% to 30%. Historically, the industry recycledthese wastes to sinter plants, but the smoke generated from the oil has made compliance withClean Air Act requirements uneconomic, and many aging sinter strands have closed. The adventof pelletized ore use in blast furnaces has discouraged the building of new sinter plants with state-of-the-art emission control technologies. Only 20% of U.S. steel plants operate sinter plants, andthey do not accept oily wastes. Therefore, most mills landfill sludges and scale at a cost of $25 to$50 per ton of scale.

The zero waste approach in this area has three elements:_- Minimize Scale Generation. Direct rolling or hot charging and good reheat furnace

management can reduce scale loss to the range of 0.5 to 1.0 percent._- Reduce Oil Contamination: One of the primary sources of oily scale is leaking bearings.

Dofasco has reported significant reductions in oil losses through the use of sealed bearings,thus reducing maintenance, operating costs, and the quantity of oil in sludge. 6 Improvedmaintenance practices can significantly reduce oil contamination.

." Oil Separation. Oily sludge is a slurry of water, oil and metallics which is difficult to separate.

A recent program by the Center for Metals Production demonstrated that significantly improvedseparation of the constituents can be obtained using microwave technology and speciallydeveloped oil release agents. 7 The products of the lab scale tests could be recycled directly.Bethlehem Steel is also designing a demonstration plant for recovery of oil and iron fromsludge.

ZERO WASTE IMPLEMENTATION

Board of directors' approval of funds to explore zero waste options may be more difficult to obtainthan for mature technologies which treat specific process problems. Waste minimization andrecycling is widely perceived to require more initial exploratory work than continued operation witha pollution control/compliance philosophy. Appropriations procedures favor low risk (tried andtrue) technology since firm details are usually required before funds are released to exploretechnology options.

An organized approach to waste minimization is required to identify and economically justifyopportunities to reduce environmental costs and/or make a valuable product from waste. Asuccessful zero waste program has five key factors:_,- Total commitment from the highest levels of management._- Cross discipline teamwork.

Clear-sighted identification of areas which provide environmental and economic opportunities._-- Objective process evaluation._- A continuous improvement outlook.To ensure that the program is successful, the steps outlined below should be followed.

Planning and Organizing Phase

It has been our experience that companies who have achieved considerable economic benefitfrom zero waste programs also have the total commitment of top management to these programs.Clear economic goals articulated by top management ensure that zero waste initiatives develop ina direction that is profitable for the company. For example, Dow Chemical expects environmentaldecisions to improve their financial bottom line through reductions in emissions, the number ofspills, injuries, etc.

A cross disciplinary waste minimization assessment team should be established to develop andimplement the program. The applied expertise of operations, engineering, metallurgy,environmental and accounting permits a balanced evaluation of potential projects. Many millsalready have cross-disciplinary teams active on quality improvement and process optimization.Their mandate could be expanded to encompass waste minimization.

Identify Pollution Prevention Opportunities

Identifying opportunities can be the most difficult portion of the pollution prevention program sinceit involves challenging basic assumptions about the mill's production processes. The processes,materials and operating practices in all plants have usually evolved over the years without anyformal review. Processareas that currentlypose a significantproblemwith respect toenvironmental compliance and/or costs are good places to start.

Prepare Process F/ow Diagrams: Process flow diagrams and energy balances for the chosenprocesses should be prepared, indicating all raw material, products and waste streams. Theinformation required is already available within the company's Title V, Clean Water Act andEmergency Response and Community Right to Know Act documents. This information can alsobe used to determine current emissions, identify major costs, and track progress from year to year.

Assign Costs to Waste Streams: It is crucial to identify all costs associated with a waste stream.Costs for waste disposal, regulatory compliance and an allowance for future liability whereapplicable should be included. An attempt must be made to evaluate those unquantifiable costsassociated with some process wastes; estimates and clearly articulated assumptions are areasonable approach.

Review Process to Identify Causes of Waste: Most often the causes of waste are poorhousekeeping, operational negligence, poor maintenance, or choice of materials.

Identify Opportunities: Pollution prevention opportunities may require operational controls,recycling programs, replacement of hazardous materials, e.g. solvents, reuse of waste or creationof a salable by-product and improved housekeeping.

Implementation

Project Selection: Initial work on projects with significant economic and environmental savings willprovide the financial base for a continuing program, as well as the encouragement necessary tomaintain momentum. The objective is to perform projects that have cost savings attached, not justenvironmental projects. If the costs of wastes were properly identified earlier, it will not be difficultto identify environmentally beneficial projects with attractive cost savings.

Implementation: Proper implementation of the recommendations is crucial to a successfulprogram. A multi-discipline team approach assures program success since it facilitates theimplementation of projects by every member working through their respective groups.

Continuous Improvement

Pollution prevention does not end with project implementation, Follow-up and continuousimprovement are crucial to pollution prevention programs. Measurement and reporting of wastereduction and cost saving goals achieved will help to justify future projects and indicate areas forfurther work.

SUMMARY

The zero waste concept can be applied to both integrated and mini-mill steel plants. Economic,regulatory and public pressures are forcing companies to continuously reduce environmentalemissions.

A zero waste perspective views environmental emissions as potential raw materials to beconserved or reused rather than wasted. A structured zero waste methodology clearly identifiesappropriate manufacturing processes and insures bottom line cost savings. Implementing theidentified projects reduces process wastes discharged, converts waste to economically beneficialmaterial and develops new processes that eliminate waste.

A successful zero-waste program is incremental. The ideal of a "zero waste" steel mill isapproachable by the continuous reduction, reuse, and recycling of wastes.

Figure 1: U.S. Steel Industry Environmental Operating Costs*

$13.00

$11.2_$12.00 $11_1 i$11.00 _'_36- I

$10.00 i $_'70-i

$9.00 158"16 I$8.00

$7.00

$6.00

$5.00

$4.OO

$3.00

$2.OO

$1.00

$0.001988 1989 1990 1991 1992 1993 1994

[3 Solid Waste|Year• Water I

* Prepared using U.S. Department of Commerce and AISI data.

REFERENCES

1 Holmberg, D.J., "33/50=86 Acme Steel Cleanup Exceeds Even Its Own Emission Goals," American MetalMarket, April 12, 1995.

2 Nashan, G., "Conventional Maintenance and the Renewal of Cokemaking Technology," Committee onTechnology, TECHNO-24, May 1992.

3 "Project Facts - Calderon Cokemaking Process/Demonstration Project," Pittsburgh Energy TechnologyCenter.

4 Ritt, A., ""DRI Comes to the Gulf Coast," New Steel, January 1996.

5 "Metal Recovery Begins De-Zincing," American Metal Market, March 27, 1996.

6 Schrama, R.C., R.M Essig, "Roll Neck Bearing Lubrication Systems," Iron and Steel Engineer, March 1989.

7 Goodwill, J.E, R.J. Schmitt, D.A. Purley, "New Developments in Microwave Treatment of Steel MillSludges," Iron and Steel Engineer, February 1996.