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Through the promotion of responsible policies that conserve energy and natural resources while sustaining a
sound economic environment, the steel industry is committed to the protection of human health and the
The steel industry has invested more than $7 billion in environmental controls over the past 30 years in order
to meet the challenge of compliance with national health-based standards. In a typical year, iron and steel plants
spend roughly 15% of their capital expenditures on environmental projects. In fact, the industry’s discharge of
air and water pollutants has been reduced by well over 90% since the early 1970s. Despite this significant
progress, further improvements in pollution prevention technologies are needed for iron and steel plants to reduce
costs, improve profitability, and facilitate compliance with changing federal regulations.
Recently promulgated and impending air and water pollution control regulations pose a daunting challenge for
the U.S. steel industry. In accordance with requirements of the Clean Air Act, EPA has established Maximum
Achievable Control Technology (MACT) standards for hazardous air pollutant emissions. Under this program,
EPA established standards for coke oven door and topside leaks and charging emissions in 1992 and placed
cokemakers on a timetable to achieve progressively more stringent standards between 1995 and 2020. In 2001,
additional MACT standards are proposed for coke oven pushing and quenching operations and coke battery
combustion stacks. Also in 2001, MACT standards are proposed for blast furnaces, sinter plants, basic oxygen
shops, and ancillary operations.
In addition to these industry-specific regulations, EPA has also revised the ambient air quality standards for fine
particulate matter (PM-2.5) and for ozone. As regulatory programs are implemented over the next few years to
achieve these ambient standards, additional control requirements are possible for iron and steel industry sources
emitting fine particles or gases that contribute to the formation of urban smog, including NOx, SOx, and VOCs.
Also, the federal air permitting process under Title V of the Clean Air Act will require additional administrative
controls and monitoring obligations.
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The industry also faces substantially tighter regulations under the Clean Water Act. EPA has proposed revisions
to Effluent Limitations Guidelines (ELGs) for the Iron and Steel Point Source Category that have been in place
since the early 1980s. The EPA is on schedule to issue these rules in final form by April 2002. The new limits
are dramatically lower than the existing ELGs and would require significant increases in recycling and more
efficient treatment for the full range of iron and steel processes. Many steel plants are already required to reduce
effluents below the previously established ELG limits because of the need to meet state and federal water quality
standards, particularly in the Great Lakes area as a result of the Great Lakes Water Quality Initiative.
Meeting these new and changing regulations requires effective R&D efforts throughout many different aspects
of the steelmaking process. To target future research, it is useful to examine the various processes and the
pollutants they produce. Although the coking process has been widely considered to pose the biggest
environmental challenge, environmental regulations affect all stages of the manufacturing and forming process.
The following sections discuss the potential pollutant output and development needs of each of the major
processes: cokemaking, ironmaking, steelmaking, refining, casting, forming, and finishing.
Cokemaking represents perhaps the greatest environmental concern to the steel industry. Although much
progress has been made, cokemaking emissions continue to be a target of federal environmental regulations.
Continual efforts to reduce emissions are necessary to ensure the stability of U.S. cokemaking; some by-products
present an additional concern. Figure 4-1 illustrates the cokemaking process with its major inputs and outputs.
Strict environmental regulations in the United States, including the Clean Air Act Amendments of 1990, threaten
the economic viability of domestic coke production. While improvements to contain emissions have been
incorporated into recent oven designs, many older cokemaking facilities cannot be retrofitted economically to
meet current and proposed environmental standards. Tighter environmental regulations threaten to accelerate
plant closures, in turn reducing domestic production capacity by approximately 30% by the year 2003. Other
developed and developing nations are expected to follow the lead of the United States with tighter environmental
regulations that will affect worldwide coke production. At present, no new by-product cokemaking technology
is guaranteed to be environmentally compliant. In fact, new MACT standards provide an incentive for non-
recovery coke ovens for new facilities. In the future, U.S. dependence on foreign sources is expected to increase.
4.1.1 Cokemaking Emissions
Typical cokemaking air emissions include ammonia, benzene-soluble organics, benzene, particulates, SOx, and
VOCs. Coke plant operators have initiated significant efforts to control these emissions and have spent millions
of dollars on environmental control systems, improved operating and maintenance practices, and increased
personnel training. These efforts have substantially reduced cokemaking air emissions over the last three decades
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Figure 4-1. Cokemaking Flow Diagram
The industry’s efforts have reduced emissions by more than 95% for benzene and VOCs from by-product
sources, particulate matter emissions from charging and pushing, and SOx emissions from the combustion of
“cleaned” coke oven gas. To reduce air emissions, the industry installed many types of new and improved
environmental hardware. Training and, more importantly, the conscientious efforts of skilled operating personnel
have also substantially reduced emissions of benzene-soluble organics from coke plant doors, lids, offtakes, and
charging emissions sources.
4.1.2 Cokemaking Effluents
The typical volume of process wastewater generated at a well-controlled coke plant is approximately 150
gallons/ton of coke produced (EPA 2000). About 25 to 35 gallons/ton are generated as waste ammonia liquor
from moisture contained in the charged coal. The balance is from the steam used in distilling ammonia from the
waste liquor, light oil recovery, and other processes.
Cokemaking wastewaters contain significant levels of oil and grease, ammonia, nitrogen, cyanides, thiocyanates,
phenols, benzenes, toluene, xylene, other aromatic volatile components, and polynuclear aromatic compounds.
Wastewaters also contain trace amounts of the toxic metals antimony, arsenic, and selenium. The amount of each
pollutant generated depends on the by-product process, specific facility equipment, practices, and the range of
constituents in the coals used.
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4.1.3 Cokemaking By Products
In the by-product coking process, volatile components are collected as unpurified “foul” gas containing water
vapor, tar, light oils, coal dust, heavy hydrocarbons, and complex carbon compounds. Condensable materials,
such as tar, light oils, ammonia, and naphthalene are removed, recovered, and processed as gas and coal chemical
by-products. Finally, sulfur is removed, leaving clean, desulfurized coke oven gas. The cleaned, desulfurized
gas is then used as fuel for coke ovens or other plant combustion processes, or it is sold to nearby facilities.
Approximately 11,000 scf of coke oven gas (at about 500 Btu/scf) is produced/ton of coal charged (EPA 2000;
AISE 1998). About 40% of the gas is used to heat the coke ovens.
4.1.4 Hazardous Cokemaking Wastes
As shown in Figure 4-1, seven listed hazardous wastes are associated with cokemaking under the Resource
Conservation and Recovery Act (RCRA). These include residues from coal tar recovery, tar storage tanks, light
oil processing units, wastewater sump residues, and naphthalene collection and recovery.
Process residues from coal tar recovery (K141) are generated when uncondensed gas enters a primary cooler.
Condensates from the primary cooler flow into the tar collecting sump and are discharged in the flushing liquor
decanter. Tar collection sump residue or sludge accumulates at the bottom of the collecting sump, and must be
recycled periodically as an individual stream, through the flushing liquor decanter, or back to the coke oven.
Tar storage tank residues (K142) are produced when residuals settle out of the crude coal tar collected as a coking
by-product. The residues are periodically removed from the storage tanks and are recycled to the oven or
Residues from light oil processing units (K143) collect in a light-oil scrubber and light-oil stripping still. Resin
is a related waste that accumulates from cleaning wash oil used in the light-oil recovery process. Wash-oil muck,
residue from a wash-oil purifier or decanter, is periodically removed and recycled to the coke oven, reclaimed
off-site, or used as