EPA-600/276267
October 1976
Environmental Protection Technology Series
MANAGING AND DISPOSING OF RESIDUES FROM
ENVIRONMENTAL CONTROL FACILITIES
IN THE STEEL INDUSTRY
industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development,
U.S. Environmental Protection Agency, have been grouped into
five series. These five broad categories were established to
facilitate further development and application of environmental
technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in
related fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed
to develop and demonstrate instrumentation, equipment and
methodology to repair or prevent environmental degradation from
point and non-point sources of pollution. This work provides the
new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
EPA REVIEW NOTICE
This report has been reviewed by the U. S. Environmental Protection
Agency, and approved for publication. Approval does not signify that
the contents necessarily reflect the views and policies of the Agency, nor
does mention of trade names or commercial products constitute endorse-
ment or recommendation for use.
This document is available to the public through the National
Technical Information Service, Springfield, Virginia 22161.
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EPA-600/2-76-267
October 1976
MANAGING AND DISPOSING
OF RESIDUES FROM
ENVIRONMENTAL CONTROL FACILITIES
IN THE STEEL INDUSTRY
by
Laszlo Pasztor and S. B. Floyd, Jr.
Dravo Corporation
3600 Neville Road
Pittsburgh, Pennsylvania 15225
Grant No. R803619
ROAPNo. 21AZN-019
Program Element No. IBB-036
EPA Project Officer: Robert V. Hendriks
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
In 1974 the United States steel industry produced 145,720,000 tret tons*
of raw steel. During the same period, approximately 16.6 million tons
of pollution abatement residues were generated by the steel industry
in the U.S. This includes all residues arising in 14 different iron
and steelmaking subcategories, but does not include iron and steelmaking
slags.
The pollution control facilities used for air and water pollution
control, the quantities and properties of the residues generated in
coking, sintering, blast furnace (iron), blast furnace (ferro-manganese),
basic oxygen furnace, open hearth furnace, electric arc furnace, vacuum
degassing, continuous casting, rolling operations, pickling operations,
coating operations, waste water treatment facilities, and boilerhouses
as well as the management and disposal of the residues are described.
The information obtained during this study from 13 American integrated
steel mills is compared with those found in the literature and with
data collected during visits to English, German and Japanese steel
mills, technical and industrial associations and government agencies.
A special section deals with recycling of iron and steelmaking pollution
abatement residues. Methods used for recycling of dusts and sludges
and the regeneration or recovery of waste acids and oils are covered.
Of the approximately 16.6 million tons of residues, 9.1 million tons are
recycled, while 7.5 million tons are dumped or "stored for later cease."
* Although EPA policy requires the use of metric units, this report
uses non-metric units for convenience in giving U.S. production
figures. Readers are encouraged to use the conversion factors on
page xi.
iii
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The major reasons for not recycling the residues, besides the economic
factors, are the higher than tolerable tramp element contents (such
as Zn, Pb, Na, K) or oil content, and the extremely fine consistency
of the residues.
In spite of these problems in recycling, with the development of new
technologies the trend is toward recycling not only most of the
process waters but also most of the iron and other metal-containing
residues as well as the waste acids and oils.
IV
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Chapter TABLE OF CONTENTS Page
Abstract ill
Table of Contents v
List of Figures vi
List of Tables vii
Conversion Factors and Abbreviations xi
Acknowledgement xii
I Conclusions and Recommendations 1
II Introduction 7
2.1 Purpose 7
2.2 Organization 8
2.3 Methods Used to Develop Information 9
2.4 General Description of the U.S. Steel Industry 11
2.5 Rationale for Subcategorization 18
2.6 General Description of Pollution Abatement
Residue Generated 20
2.7 References 24
III Pollution Abatement in the Iron and Steel Industry
Category, by Subcategories 25
3.1 Coking 26
3.2 Sintering 35
3.3 Blast Furnace (Iron) 47
3.4 Blast Furnace (Ferromanganese) 63
3.5 Basic Oxygen Furnace (EOF) 67
3.6 Open Hearth Furnace (OH) 80
3.7 Electric Arc Furnace (EAF) 91
3.8 Vacuum Degassing 100
3.9 Continuous Casting (CC) 104
3.10 Rolling 109
3.11 Pickling 127
3.12 Plating and Coating 133
3.13 Boilerhouses 136
3.14 Waste Water Treatment Plants 140
3.15 Miscellaneous Other Operations 153
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Chapter TABLE OF CONTENTS
3.16 Recycling
Appendix Methods used in Analyzing Steel Industry
Pollution Control Residues
Page
156
174
II 2-1
III 3.1-1
3.14-1
3.14-11
3.14-III
3.14-IV
3.14-V
3.14-VI
3.14-VII
3.14-VIII
3.14-IX
FIGURES
Steelmaking from Raw Materials to
Finished Mill Product
Biological Coke Waste Treatment Plant
Schematic
Waste Water Treatment Plant Schematic
Plant B
Waste Water Treatment Plant Schematic
Plant D
Waste Water Treatment Plant Schematic
Plant E
Waste Water Treatment Plant Schematic
Plant F
Waste Water Treatment Plant Schematic
Plant G
Waste Water Treatment Plant Schematic
Plant H
Waste Water Treatment Plant Schematic
Plant I
Waste Water Treatment Plant Schematic
Plant J
Waste Water Treatment Plant Schematic
Plant K
17
30
144
145
146
147
148
149
150
151
152
vi
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Chapter TABLES Page
II
2-1 Iron and Raw Steel Production in the U.S. 12
2-2 Blast Furnace Production 13
2-3 Raw Steel Production by Type of Furnace 14
2-4 Material used by Blast Furnaces in Manufacture
of Iron (Pig and Molten) in 1974 15
2-5 Industry Consumption of Scrap and Pig Iron by
Types of Furnaces 16
2-6 Categorization and Subcategorization of the
Iron and Steel Industry 19
2-7 Quantities of Pollution Control Residues
Generated in Various Iron and Steelmaking
Operations 22
2_s Estimates of Iron and Steel Mill Pollution
Control Residues in the U. S. in 1974 23
III
3.1-1 Quantities of Coke Breeze and Coking Pollution
Control Residues Generated in Steel Mills 31
3.1-2 Raw Residual Loads Associated with Coke
Manufacturing Operations 33
3.2-1 Analysis of Sintering "Windbox" End Pollution
Control Residues 39
3.2-2 Analysis of Sintering "Discharge" End Pollution
Control Residues 40
3.2-3 Analysis of Sinter Plant Dust (from Literature) 41
3.2-4 Particle Size Analyses of Sinter Plant Residues 42
3.2-5 Types and Quantities of Residues Generated in
U.S. Sintering Operations and their Disposal 44
3.2-6 Raw Residual Loads Associated with Sinter Plant
Operations 45
3.3-1 Chemical Analyses of Blast Furnace Residues -
Dust (Part 1) 52
Chemical Analyses of Blast Furnace Residues -
Sludges (Part 2) 53
3.3-2 Chemical Analyses of Blast Furnace Residues
(from the Literature) " 54
3.3-3 Particle Size Distribution of Blast Furnace
Dust and Sludges 55
vii
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Chapter Page
3.3-4 Blast Furnace Dust and Sludge (Residues)
Collected (1974) 56
3.3-5 Blast Furnace Residues Disposition - 1974 57
3.3-6 Typical Ranges of Quantities of Residues
Collected by BF Operations by Countries 58
3.3-7 Raw Residual Loads Associated with Blast Furnace
Operations 59
3.4-1 Chemical Analyses of BF Ferromanganese Dust and
Sludges 64
3.4-2 Particle Size Analyses of BF Ferromanganese
Dust and Sludges 64
3.5-1 Chemical Analyses of EOF Residues - Fines 70
3.5-2 Chemical Analyses of BOF Residues - Sands 71
3.5-3 Chemical Analyses of BOF Residues (from
Literature) 72
3.5-4 Particle Size Analyses of BOF Residues 73
3.5-5 BOF Sludge and Dust Collections - 1974 74
3.5-6 BOF Residues Disposition - 1974 75
3.5-7 Quantities of BOF Pollution Control Residues
Collected by Countries 76
3.5-8 Raw Residual Loads Associated with BOF Steel
Manufacturing Processes 77
3.6-1 Percent of Raw Steel Produced by Furnace Type 80
3.6-2 Chemical Analyses of Open Hearth Dusts 85
3.6-3 Chemical Analyses of Open Hearth Residues
(from Literature) 86
3.6-4 Particle Size Analyses of Open Hearth Dusts 87
3.6-5 Quantities of Residue Generated in Open Hearth
Steelmaking Operations 87
3.6-6 Raw Residual Loads Associated with the Open
Hearth Steel Manufacturing Processes 88
3.7-1 Chemical Analyses of EAF Residues 93
3.7-2 Chemical Analyses of EAF Residues (from
Literature) 94
3.7-3 Particle Size Analyses of EAF Residues 95
3.7-4 Quantities of Residues Generated in EAF Operations 96
viii
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Chapter Page
3.7-5 Raw Residual Loads Associated with EAF Steel
Manufacturing Process 97
3.9-1 Raw Residual Loads Associated with Continuous
Casting 106
3.10-1 Shipments of Steel Products - 1974 (All Grades,
including Carbon, Alloy and Stainless) 111
3.10-2 Residues Collected in Rolling Air Pollution
Control Facilities 112
3.10-3 Waste Process Water Treatments for Hot Rolling
Operations 113
3.10-4 Chemical Analyses of Steel Conditioning Residues 116-117
3.10-5 Scale Collection and Disposition 118
3.10-6a Iron and Oil Content of Rolling Mill Scales 119
3.10-6b Chemical Analyses of Rolling Mill Scales (from
the Literature) 120
3.10-7 Chemical Analyses of Hot Rolling Mill Sludges 121
3.10-8 Quantities of Rolling Mill Sludges Generated and
their Disposal 122
3.10-9 Quantities of Residues Generated in Rolling
Operations by Countries 123
3.10-10 Raw Residual Loads Associated with the Hot
Rolling and Cold Finishing Operations 125
3.11-1 Acids Used and Methods of Spent Liquor Disposal 129
3.11-2 Disposition of Waste Pickling Rinse Waters 129
3.11-3 Chemical Analyses of Pickle Sludge 130
3.13-1 Chemical Analyses of Fly Ashes from Southwestern
Pennsylvania Area 137
3.13-2 Chemical Analyses of Lime and Limestone FGD
Sludges 138
3.14-1 Chemistries of Waste Water Treatment Plant
Sludges 142
3.14-2 Quantities and Disposition of Waste Water
Treatment Plant Sludges 143
3.15-1 Miscellaneous Facilities Associated Regularly
(or Occasionally) with Iron and Steel Mill
Operations 153
IX
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Chapter Page
3.16-1 Estimates of Iron and Steel Industry Pollution
Control Residues in the U.S. in 1974 and
Comparison of % of Residues Recycled in the U.S.
and Abroad 157
3.16-2 Relative Quantities of Residues Recycled, Sold,
"Stored" and Dumped in the U.S. 158
3.16-3 Methods of Beneficiation of Iron and Steel Mill
Environmental Pollution Control Residues 161
3.16-4 Chemical Composition of Waelz Oxides 164
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CONVERSION FACTORS AND ABBREVIATIONS
Conversion Factors
1 kg (kilogram)
1 t (metric ton)
1 m (meter)
3
1 m (cubic meter)
1 1 (liter)
2.2 pounds
1.1 short ton
3.3 feet
35.3 cubic feet
0.26 gallon
Abbreviat ions
AISI
BF
EOF
BSC
CC
EAF
ESF
FGD
JISF
NA
OECD, ED
OH
VDEh
American Iron and Steel Institute
Blast furnace
Basic oxygen furnace
British Steel Corporation
Continuous casting
Electric arc furnace
Electrostatic precipitator
Flue gas desulfurization
Japan Iron and Steel Federation
Not available
Organization for Economic Cooperation and
Development, Environment Directorate
Open hearth
Verein Deutcher Eisenhuttenleute (Germany)
xi
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ACKNOWLEDGEMENT
This study was prepared for the Industrial Environmental Research
Laboratory of the U.S. Environmental Protection Agency by Dravo
Corporation. The authors wish to express their appreciation to the
American Iron & Steel Institute, to its Technical Committee on
Environmental Quality Control, the British Steel Corporation, The Iron
and Steel Federation of Japan, and the Verein Deutscher Eisenhutten-
leute (Germany) for supplying data and making arrangements for the
various plant visits.
The authors also feel indebted to the representatives of Armco Steel
Corporation, Bethlehem Steel Corporation, Inland Steel Corporation,
Jones & Laughlin Steel Corporation, Kaiser Steel Corporation, National
Steel Corporation, Republic Steel Corporation, and United States Steel
Corporation for making the plant visits possible and for reviewing their
individual plant reports. The AISI representative, Mr. David Boltz,
who accompanied the authors on all of these visits to the U.S. steel
plants, and Dr. Hugh B. Durham, who was the first EPA Project Officer
of this grant, deserve special acknowledgement for their efforts.
The fine cooperation of the BSC's In-Plant Fines Group and the Appleby-
Frodingham Steel Works, the Hoesch Huttenwerke A.G.'s Phoenix Horde,
Hermanns Hutte, Union and Westfalenhutte Iron and Steel Works, the
Mannesmann A.G.'s Huttenwerke and Rohrenwerke, the Nippon Steel
Corporation's Kimitsu Works, the Nippon Kokan K.K.rs Fukuyama Works,
and the Kawasaki Steel Corporation's Mizushima Works, for making
arrangements for meetings and plant visits is appreciated, as well as
the information supplied by the pollution control agencies in Germany
and Japan, the Gesellschaft fur Systemtechnik and the Krupp Industrie-
und Stahlbau in Essen, Germany, the UHDE GmbH in Dortmund, and the
Lurgi Chemic und Huttentechnik GmbH in Frankfurt, Germany, and the
Industrial Pollution Control Association of Japan.
xii
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CHAPTER I CONCLUSIONS AND RECOMMENDATIONS
1.1 CONCLUSIONS
The Federal Water Pollution Control Act, the Clean Air Act, their
amendments and the regulations for their implementation, are aimed at
providing an effective program to improve the quality of the nation's
water and air. Due to these strict pollution control laws and
regulations, including pollutant discharge limitations, large
quantities of dusts and sludges are generated during the removal of
the pollutants from the air, off-gases, industrial and process waters.
These dusts and sludges are often called pollution control residues
or simply residues.
The management and disposal of these residues have created new
pollution problems. Their large quantities, their pollution-prone
consistencies (fine dusts or dried sludges can dust when exposed to
winds) and their land, water (run-off) and ground-water-polluting
potentials concern both industry and the government.
The many pollution control facilities in the tn.S'. steel industry
generate a total of more than 16 million tons of residues/year. As
shown in this study, more than 100,000 tons/year of residues (dusts and
sludges - dry basis) are generated in each of ten subcategories or
operations. From raw material processing to finishing operations,
the quantities arising/year in million tons in the subcategories are:
coking - 1.0; sintering - 0.9; blast furnace (BF) - 3.3; basic oxygen
furnace (EOF) - 1.7; open hearth furnace (OH) - 0.5; electric arc
furnace (EAF) - 0.4; continuous casting (CC) - 0.2; rolling - 7.4,
and pickling - 0.4. In addition, large quantities of sludges (0.7
million tons) are also generated in the joint waste water treatment
plants in which effluents from two or more of the above-mentioned
primary and, in some cases, secondary water treatment Operations are
further processed (see Chapter II, Table 8).
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The residues are either (1) recycled (or sold), or (2) "stored" for
future recycling, or (3) dumped, or (4) sometimes used for a useful
purpose. There is also another way to "dispose" of the residues, and
that is to eliminate their generation by converting the wastes to
commercial by-products.
Presently, approximately 60% of the iron and steel mill pollution
control residues are recycled in the U.S. Essentially 100% of the
presently generated coking, sintering and coating residues are recycled.
The first two are usually reused in the steel plants while the coating
residues are reprocessed by the suppliers of the coating materials.
Approximately 80% of the BF, 65% of the rolling, and 50% of the
continuous casting residues are also recycled, while only 25% or less
are reused from the remaining steel mill operations.
Additional large quantities of residues are presently "stored" for
future recycling, awaiting either the development of new technologies
capable of recycling them in a technically and economically feasible
way, or the construction of new agglomerating facilities capable of
handling the quantities of residues generated in pollution control.
Almost one-half of the presently not-recycled residues are "stored"
for this reason. The other half of the not-recycled residues are dumped.
For dumping, well-defined areas, not normally accessible to the public,
are used. Ravines, valleys, often closed with earth dikes or small
dams, are commonly used as dumping sites. Occasionally the dumping
areas are lined with clay or tar to avoid ground water contamination.
The residues and wastes are sometimes also used for some practical
purposes. For instance, waste pickling liquor for municipal water
treatment or for neutralization of alkaline wastes; or dirty waste oils,
and scum and tar for dust control on temporary roads. However, the
quantities directed to such purposes are quite small.
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The regeneration of hydrochloric acid or recovery of sulfuric acid are
good examples of processes that eliminate troublesome wastes. Here,
instead of generating neutralization sludges (usually hard to recycle
or dispose of), commercial by-products are manufactured. Therefore,
the problem of residue management and disposal is automatically solved.
To eliminate the possibility of secondary pollution from the dumped
pollution control residues and also to conserve mineral resources, the
recovery of iron and other non-ferrous values such as zinc, lead,
carbon, oil, acids, etc., by recycling the residues is the best approach
in managing and disposing of the iron and steel works pollution
control residues. In most cases, the U.S. iron and steel industry is
moving in this direction, as demonstrated by the fact that
approximately 60% of the residues are already recycled and another 20%
are "stored" (for future reuse).
The problem of not recycling the residues originates not only from the
technical difficulties in handling some of the residues, as pointed
out in Section 3.16, Recycling, but also from the following facts:
1) Thus far, there is no single process available for recycling or
pre-treating all residues, as a mixture or in subsequent operations,
using the same facility.
2) Some of the new processes (e.g., used for recycling of the large
quantities of zinc and lead or oil-containing residues) are not
yet generally accepted as technically and economically feasible
technologies.
3) Most of the U.S. steel corporations do not produce large enough
quantities of residues (requiring special processes for recycling
or pre-treatment) in one location, to make investment in such
facilities feasible.
4) The large capital outlays needed to build these (in some cases,
still experimental) facilities is not easily available to the
steel companies, and
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5) The uncertainty about future regulations affecting the disposal
and/or recycling of the residues make the investment in
recycling operations risky.
1.2 RECOMMENDATIONS
Based on the conclusions of our study and the data and information
obtained in England, Germany and Japan, the recommendations described
in the following paragraphs can be made:
The U.S. EPA ORD should continue the work on the management and disposal
of residues from the environmental control facilities of the iron and
steel industry. The work should be concentrated on and high priority
should be given to the recycling of (a) zinc and lead-containing iron
and steelmaking dusts and sludges, and (b) oil-containing sludges.
In the area of zinc and lead-containing sludges, a technical and
economic feasibility study should be commissioned (Phase I) to
establish the optimum conditions for recycling of these wastes. As a
part of this effort, the use of small installations serving individual
mills vs. regional installations serving several steel mills in the
same area, should be evaluated. The study should also include a
comparison of the advantages and disadvantages of the various available
methods with specific coverage of the SL/RN, the Berzelius (Waelz)
and the Kawasaki processes.
As a part or a continuation of this study, a demonstration project or
projects should be initiated (Phase II) using existing facilities
(U.S. or foreign). In this project, several presently not-recycled,
typical, zinc and lead (and other tramp element) containing residues
from various U.S. steel mills should be treated or pre-treated, to
make them suitable for recycling in iron and/or steelmaking operations.
The recovery of zinc and lead in these processes would also be
evaluated because the economic feasibility of these operations seems
to depend on the possibility of also recycling the zinc and lead.
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Depending on the findings of the Phase I study, the construction of a
U.S. plant for the recycling of zinc and lead-containing residues
as an alternative to or a follow-up of the Phase II demonstration
project could be considered. This plant, supported with EPA and other
funds, would serve as a full-scale demonstration operation. It could
be a small facility serving only one mill or it might be a larger
regional residue treatment-recycling installation.
To study the recycling of the oil-containing wastes, the U.S. EPA ORD
effort should be directed toward:
1) The separation of oils from the effluents before the residues
are generated or removed for disposal or recycling, and
2) The separation of oil from the residues in a pre-treatment
step before the agglomeration and recycling of the residues.
Again, the commissioning of a feasibility evaluation by the U.S. EPA
ORD can be recommended as Phase I. Such a study should determine the
technical and economical merits of recycling oily wastes (including
the oil recovery aspects of such processes). The evaluation of various
already-used oil (physical, physicochemical, solvent extraction and
chemical, including emulsified oil-water and oil-sludge) separation
systems should be included in such a study. This approach (Phase I)
should lead to demonstration projects after the selection of the best
processes (Phase II).
*********************
The support cf such projects by the U.S. EPA ORD would help the industry
to decide on the selection of the most suitable systems &f their
specific requirements for the recycling of presently "stored" or
not-recycled tramp element or oil-containing residues. At the same
time, the study and demonstration projects would help the U.S. EPA ORD
and the state and local environmental authorities to demonstrate that
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economically and technically feasible processes are available for the
recycling of even those presently not-recycled steel mill residues.
We estimate that of the presently dumped or "stored" 7 million tons of
steel mill residues per year, close to 90% (or more than 6 million
tons) would be recycled if the availability of technically and
economically feasible processes for the recycling of residues can be
demonstrated to the steel industry. Even for the industry, the
economically feasible recycling of residues is the most attractive
solution to the management and disposal of pollution control residues,
if the capital can be made available to build such facilities.
For the residues which cannot be recycled as waste, or which are
generated during the recycling processes as final wastes, residue
stabilization methods should be developed to make the environmentally
safe disposal of these residues possible.
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CHAPTER II - INTRODUCTION
2.1 PURPOSE
The implementation of the Federal Clean Air Act and the Federal Water
Pollution Control Act, and especially their major amendments (the
Federal Water Pollution Control Act Amendments of 1972, and the Clean
Air Amendments of 1970) resulted in the removal of various pollutants
from the air and water.
Because of this effective program to improve the quality of our nation's
air and water, large quantities of pollution abatement residues
(residues) are generated in the pollution control facilities of the iron
and steel industry. The handling and disposal of these residues
present new environmental problems.
The purpose of this U.S. EPA Grant R-803619 was to establish (1) in
what subcategories of the United States iron and steel industry residues
are arising; (2) in what general types of pollution control facilities
the residues are generated; (3) in what quantities the residues are
collected; (4) what are the chemical composition and main physical
characteristics of the residues; (5) how the residues are managed and
disposed of, and (6) what the trends are in the management and disposal
of these residues.
It was also the purpose of this study to determine the differences, if
any, in the above-mentioned areas (1-6) between the steel works of this
country and those of other major steel producing nations.
Special attention was to be given to the recycling of the residues,
their useful application or potential uses, including resource recovery
of metallic and other components such as acids and oils, and to the
problems which may make their recycling or useful application impractical.
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Finally, it was also the purpose of this study to make recommendations,
based on our findings, to the U.S. EPA for future research and
demonstration projects which might help to solve the problems of
disposal of the generated residues. The research and demonstration
projects would, hopefully, lead to resource recovery, reuse, or at
least to the stabilization and environmentally safe disposal of the
residues, dusts, sludges and other final wastes originating from iron
and steelmaking operations.
2.2 ORGANIZATION OF REPORT
The conclusions of our study and the recommendations for further
research and demonstration projects are described in Chapter I.
This introduction, Chapter II, describes the approaches used to develop
the information,the statistical data, and a general description of
the United States iron and steel industry as a whole. This is followed
by the rationale used for the categorization and subcategorization of
the industry, and a general description of the types and quantities of
residues generated in the various subcategories.
In Chapter III (Pollution Abatement Categorization by Subcategories)
essentially the same approach is used to describe and discuss in detail
each of the 14 subcategories: coking; sintering; blast furnace (iron);
blast furnace (ferro-manganese); basic oxygen furnace; open hearth
furnace; electric arc furnace; vacuum degassing; continuous casting;
rolling operations; pickling operations; coating operations; waste water
treatment operations, and boilerhouse.
First, the purpose of the iron or steelmaking operations covered in the
subcategory is described: what products, from what raw materials, in
what type of facilities and in what quantities they are manufactured.
The second part contains the description of the types of pollution control
facilities used, the types of residues generated, their chemical and
physical properties, and the quantities expressed as kg/ton of product
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generated. To present the data, whenever reasonable, tables are used
and in them the data obtained from the literature are also included.
This is followed by a review of the methods used for the disposal of
the residues, including estimates on the percent reused, sold or "stored"
for future recovery and dumped.
Finally, the information and data obtained on U.S. practices are compared
with those of other major steel-producing countries.
2.3 METHODS USED TO DEVELOP INFORMATION
We asked the American Iron and Steel Institute (AISI) for help and
guidance in obtaining the necessary information on the types, quantities,
properties, management and disposal of residues generated in the United
States iron and steel industry. After meetings with the representatives
of the AISI, the Technical Committee on Environmental Quality Control
of the AISI advised us that they had approved a procedure for us to
follow in connection with our subject study.
The AISI assured the cooperation of eight of the nine largest U.S. steel
producers with a total raw steel production of 105.7 million tons in
1974. This cooperation allowed the authors, in the company of a
representative from the AISI Technical Committee on Environmental Quality
Control, to visit 11 integrated steel works, having a total of about 35.1
million tons of raw steel production in 1974. They also made arrangements
to obtain samples and some data from two additional works having an
output of roughly 5.3 million tons.
Based on the fact that raw steel production in the United States during
1974 was 145.72 million tons^ , it can be stated that companies
representing about 73% of the United States steel production cooperated
through the AISI in our study. The production of the 11 works visited
represents 24% and the 13 works from which samples were obtained, 28%,
of the total raw steel produced in 1974 in the U.S. The AISI was of the
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opinion that the plants visited were representative of the U.S. steel
industry, and further visits or samplings would not significantly
alter the results of our study.
After the preliminary arrangements were made for the plant visit, each
company received a detailed questionnaire (of 18 pages), with a
covering letter explaining the purpose of the study. The companies
were asked to fill out the questionnaires before the plant visits and
have them available to facilitate our work during the visits. However,
not all companies complied and, in some cases, a considerable period
after the visit elapsed before we got the completed questionnaire.
Each plant visit started out with an introduction by the representative
of the AISI explaining the reasons for their cooperation. This was
followed by a general review of the purpose of our visit. Subsequently,
using the completed questionnaire when possible, the various operations
(subcategories) of the works were reviewed and production figures
checked. The pollution control facilities described and the types and
quantities of residues generated in the various pollution control and
waste treatment facilities were discussed, along with the fate (reuse
or disposal) of the residues.
The second part of the plant visit was a tour of the pollution control
facilities of the works during which the operation and performance of
the facilities and the generation of the residues was explained and
disposal sites visited. After the plant visit, a final question-and-
answer period followed, in which the data and information collected during
the visit was reviewed. When necessary, additional information and/or
samples were requested.
After each plant visit, a trip report was issued and sent to the steel
company for approval. The steel companies reviewed the information and
data we collected and approved our report, usually with no or only minor
10
-------
changes. Subsequently, the data and information were reorganized and
used in the appropriate subcategory (chapter) of our study.
In connection with our study, more than 200 residue samples were
analyzed. The samples included iron and stealmaking dusts and sludges,
coking, sintering, steel processing (including rolling, pickling,
coating), power plant and waste water treatment dusts and sludges.
Simultaneously, a literature search was made during which more than
500 articles on the subject matter were reviewed.
The British Steel Corporation (BSC), the Verein Deutscher Eisenhuttenleute
(VDEL), and The Japan Iron and Steel Federation (JISF) were contacted
and offered cooperation in obtaining information on the arising,
management and disposal of residues generated in the pollution control
facilities of the British, German and Japanese steel industry. As a
result of this cooperation, two steel works were visited in England,
five in Germany, and three in Japan, with a total annual production of
5, 11 and 40 million tons in the 2, 5 and 3 steel, works, respectively.
In addition to the foreign plant visits, a meeting was held with the
In-Plant Fines Group of the BSC and two meetings in Germany with the
environmental specialists of the VDEL, the Wirschaftsvereinigung
Eisen-und Stahlindustrie and the German government. In Japan one meeting
was held with the JISF Committee on Wastes of the Committee on Industrial
Location and Environmental Pollution, and one meeting with each of two
Japanese government agency representatives (the Environment Agency and
the Ministry of International Trade and Industry).
2.4 GENERAL DESCRIPTION OF THE U.S. STEEL INDUSTRY
The United States iron and steel industry produced 145,720,000 tons of
raw steel in 1974 and 150,799,000 tons in 1973. During the same period
the total world production of raw steel was 782,818,000 and 768,570,000
tons, respectively. In other words, the U.S. accounted for 18.6% of the
world raw steel production in 1974 and 19.6% in 1973.
11
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Iron and raw steel production figures for the U.S. by steelmaking
furnace type for 1973 and 1974 were as follows:
Table 2-1 IRON AND RAW STEEL PRODUCTION IN THE UNITED STATES
(thousands of net tons)
(1)
Year
1974
1973
Iron
Blast Furnace
95,909
101,208
Raw Steel
Basic
Oxygen Process
81,552
83,260
Open Hearth
35,499
39,780
Electric
Arc Furnace
28,669
27,759
Total
145,720
150,799
The blast furnace production has increased rather slowly in the last ten
years from 88,105,000 tons to 95,909,000 tons in 1974, as can be seen in
Table 2-2.
During the same period, however, the open hearth furnace raw steel
production decreased significantly from 94,193,000 tons to 35,499,000
tons while the basic oxygen process raw steel production increased from
22,879,000 to 81,552,000 tons and the electric arc furnace production
increased from 13,804,000 to 28,669,000 tons (Table 2-3).
In the production of pig and molten iron, various raw materials are used
(Table 2-4X Iron ore, including agglomerated iron ore, coke and flux
(mainly limestone and dolomite) are the main raw materials needed for
iron production, but scrap and other solid wastes such as coarse roll
scale and mill cinder are also used as iron-rich raw materials.
The pig and molten iron produced in blast furnaces is used for the
production of steels and iron (direct) casting. The other main raw
material used in steelmaking is scrap. The consumption of pig iron
12
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Table 2-2 BLAST FURNACE PRODUCTION
(thousands of net tons)
(1)
Year
1974
1973
1972
1971
1970
1969
1968
1967
1966
1965
Basic
91,193
96,202
83,961
77,341
86,438
89,888
83,396
81,344
83,374
80,431
Bessemer
1,100
1,242
1,336
1,215
1,447
1,306
1,437
1,722
2,882
2,716
Low
Phosphorus
106
101
105
145
146
96
169
166
209
220
Foundry
1,528
1,581
1,977
1,214
1,707
1,850
1,536
1,550
1,673
1,599
Malleable
1,382
1,352
1,193
1,336
1,415
1,456
1,804
1,830
2,848
2,806
All Other
(Silvery
Pig Iron,
Direct
Castings)
600
359
370
48
282
421
438
372
415
413
Total
Iron
95,909
100,837
88,942
81,299
91,435
95,017
88,780
86,984
91,500
88,185
Ferro-
alloys
a.
371
458
393
381
463
553
663
650
674
Total
Blast
Furnace
Production
95,909
101,208
89,400
81,692
91,816
95,480
89,333
87,647
92,150
88,859
Included in All Other.
-------
Table 2-3 RAW STEEL. PRODUCTION BY TYPE OF FURNACE
(thousands of net tons)
(1)
Year
1974
1973
1972
1971
1970
1969
1968
1967
1966
1965
a
Open Hearth
35,499
39,780
34,936
35,559
48,022
60,894
65,836
70,690
85,025
94,193
Basic
Oxygen Process
81,552
83,260
74,584
63,943
63,330
60,236
38,812
41,434
33,928
22,879
Electric
: Arc Furnace
28,669
27,759
23,721
20,941
20,162
20,132
16,814
15,089
14,870
13,804
Total
145,720
140,799
133,241
120,443
131,514
131,262
131,462
127,213
134,101
131,462
a Basic and acid open hearth production.
14
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Table 2-4 MATERIAL USED BY BLAST FURNACES IN MANUFACTURE
OF IRON (PIG AND MOLTEN) IN 1974^
Products
Ore
Iron ore (incl. manganiferous and block)
Manganese ore (incl. ferruginous manganese)
Agglomerated products (sinter, pellets, etc.)
TOTAL ores and agglomerated products
consumed
LESS flue dust and sludge produced
NET - ores & agglomerated products consumed
Scrap
Total scrap consumed
LESS produced at blast furnaces & auxiliary
units
NET - scrap consumed
Mill cinder, roll scale, etc.
Limestone, dolomite, other flux materials >
Coke
Total coke consumed in blast furnaces
LESS coke breeze (dust) recovered
NET - coke consumed
Thousands
of
Net Tons
41,163
195
116,984a
158,342
3,156
155,186
4,612
1,612
3,000
4,587
23,389
' 60,606
2,165
58,441
Net Tons
Per Ton
of Iron
Produced
0.429
.002
1.220
1.651
.033
1,618
0.048
0.017
0.031
0.048
0.244
0.632
0.023
0.609
a Includes production at or near mine site and at other locations.
b Based on total limestone and dolomite charged directly into blast
furnace, plus tonnage consumed in the production of agglomerates,
15
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(including molten iron) and scrap by types of furnaces (e.g., in 1974)
was as follows:
Table 2-5' INDUSTRY CONSUMPTION OF SCRAP AND PIG'IRON BY
OF FURNACES
(thousands of net tons)
TYPES
Year
1974
Type of Furnace
Open hearth
Basic oxygen process
Electric
Cupola^
Direct castings
Blast
Other (incl. air furnace)
TOTAL
Consumed
Scrap
18,922
25,448
28,920
705
4,447
696
80,138
Pig Iron a
23,383
65,443
1,060
263
499
92,525
Total
42,305
91,891
29,980
968
1,877
4,447
1,195
172,663
a Excluding molten iron used in direct castings.
(Source: Bureau of Mines)
The steel produced in the various steelmaking facilities may be further
treated in vacuum degassing or other refining operations before it is
either cast into molds or continuously cast into billets, slabs, etc.
The ingots from the molds (after heat treatment in soaking pits) enter
the primary rolling mills, where they are converted to blooms, billets
or slabs. These blooms, billets and slabs, usually referred to as
semi-finished steel, are rolled in hot rolling mills after heat treatment
and, if desired, subsequently in cold rolling mills.
A flow sheet (Fig. 2-1) on steelmaking from raw materials to finished
mill products shows the main steps in iron-steelmaking and finishing
operations, including the most significant coating operations.
16
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By-product
Plant
By-products
Coke
Limestone
crushing,
screening/
etc.
Prepared
limestone'
High grade
iron bearing
materials
Continuous
Casting
Machine
Pice s
Tubes.
Heating
Fu JTH.3.G G S
1— •>
Skelp
mills
Plate
mills
Hot-
strip
mills
Skelp ,
/
Contin. 1
butt —we Id. 1
pipe mill
Cold
reduction'
s
• ?
Plates ^
'
Hot-rolled sheets
and strips ""
Cold-rolled &
Hot-
rolled
breakdowns
in coil form
mills
Boiler
House
Figure 2-1 STEELMAKING PROM RAW MATERIALS TO FINISHED MILL PRODUCTS
Waste
Water
Treatment
strip (includ.
black plate)
< Electrolytic
(Hot dip)
f«ot dip galv.
> Electro, galv.
Terne
"(Sn-Pb)
• Aluminum
. Other coatings
-------
A general description of various iron and steelmaking operations is
given in the introductory part of each chapter dealing with one of the
steps of iron and steelmaking.
A detailed, in-depth description of the iron and steelmaking and
finishing operations can be found, among others, in "The Making, Shaping
and Treating of Steel - Ninth Edition," United States Steel
Corporation, 1971(2).
2.5 RATIONALE FOR SUBCATEGDSIZATION
In the subcategorization of the United States iron and steel industry
category, the following were taken into consideration:
A. Prior categorization and subcategorization used in U.S. EPA
document ;
B. Manufacturing processes and products;
(4)
C. Standard Industrial Classification (SIC)
D. Size and location of works;
E. Pollution control residue generating facilities, and
F. Quantities of pollution control residues generated.
After all of these factors were considered, we concluded that to include
all operations — found even in complex integrated iron and steel works -
generating significant quantities of pollution abatement residues,
the steel industry can be, for the purpose of our study, subcategorized
into fifteen (15) subcategories, as described in Table 2-6. The 15
(3)
subcategories cover 11 of the 12 subcategories of the EPA document .
The beehive coke subcategory was omitted because only an insignificant
quantity (< 1%) of metallurgical coke is manufactured in beehive coking
operations today. The two basic oxygen furnace (EOF) subcategories
(semi-wet and wet) and the two electric arc furnace (EAF) (semi-wet and
wet) subcategories in the EPA document are discussed in one EOF and one
EAF subcategory in our report. However, new subcategories were
established based on SIC Group 331 description to include rolling,
pickling, coating and waste water treatment operations and the always-
18
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present iron and steel mill-related boilerhouse operations. From the
SIC Group 331 series, in Industrial No. 3313, only electro-metallurgical
steelmaking was included because the only ferro-alloy operation in the
U.S. steel mills we visited was a blast furnace-ferromanganese
operation, already covered as in the EPA document in a separate
subcategory.
Table 2-6 SUBCATEGORIZATION OF THE IRON AND STEEL INDUSTRY
CATEGORY
1. Coke-making operations
2. Sintering
3. Blast furnace - iron
4. Blast furnace - ferromanganese
5. Basic oxygen furnace
6. Open hearth
7. Electric arc furnace
8. Vacuum degassing
9. Continuous casting
10. Rolling operations
11. Pickling operations
12. Coating operations
13. Waste water treatment operations
14. Boilerhouse (power plant)
15. Miscellaneous other operations (direct reduction,
lime kilns, etc.)
The 11 plants visited in the United States and the two additional plants
from which samples and information were obtained produced the following
amounts (thousand net tons) of raw steel in 1974:
810; 857; 1,350; 1,720; 1,820; 2,700; 2,865; 2,920;
3,882; 4,227; 4,430; 4,800, and 8,043-
19
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The locations of the plants are the following:
Northeastern 2 Middle Atlantic 4
Northern Great Lakes 4 Southern 2
Western 1
The 13 steel plants had the following installations in which pollution
control facilities were generating residues:
All plants had rolling pickling and boilerhouse operations; 12 had
blast furnaces (iron); 10 had basic oxygen furnaces, coating operations
and waste water treatment plants; 9 had coking (by-product); 8 had
sintering; 6 had open hearth furnaces; 5 had electric arc furnaces and
continuous casting; 3 had vacuum degassing, and 1 had blast furnace
(ferromanganese) operations.
During our study it became evident that presently most of the residues
generated in the pollution control facilities of the iron and steel
industry are arising in eight subcategories: coking, sintering, blast
furnace (iron), basic oxygen process, open hearth furnace, electric arc
furnace, rolling and pickling. However, to also make our study more
comprehensive, six other subcategories were studied and, for the
present, even less important residue-generating facilities a
"Miscellaneous Other Operations" was established for the purpose of
this study.
2.6 GENERAL DESCRIPTION OF POLLUTION ABATEMENT RESIDUES GENERATED
In our research, "dry," "wet" and "semi-wet" pollution control residues
were considered. "Dry" residues are generated in mechanical collectors
(such as primary dust catchers, cyclones, etc.), "baghouses" and dry
electrostatic precipitators. "Wet" residues are generated in scrubbers
(usually the venturi type), wet electrostatic precipitators, wet cyclones,
coarse separators, clarifiers, scale pits, filters (gravity, vacuum or
pressure), centrifuges and in various other waste water treatment
facilities, including settling ponds.
20
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"Semi-wet" residues are arising when dry residues are wetted (e.g., in
pug mills to make the handling of the fine dusts easier) or in drying
facilities where most of the water is removed again to make the
handling and/or disposal environmentally more attractive.
The consistency of the residues varies from coarse particles (e.g.,
coarse scale collected in scale pits or iron and steelmaking residues
collected in "dust catchers" or "coarse separators") to very fine dusts
or fine solid particles in sludges.
Not only the consistency but also the quantities of residues generated
can vary even from the same type of iron and steelmaking or finishing
operation from mill to mill and even within the same mill from shop to
shop, depending on the efficiency of pollutant removal, iron and
steelmaking process practice, type and degree of finishing operations,
the physical consistency (e.g., hardness and particle size) of the raw
materials and the chemical composition of and the ratios of the raw
materials used.
The effect of the above variables (even when the pollutant removal
efficiency is essentially the same) explains the differences in the
quantities of residues generated in the various subcategories of iron
and steelmaking, as shown in the following Table 2-7.
In the data, we took into consideration all information obtained from
13 United States, 2 English, 3 Japanese and 4 German integrated steel
mills as well as the data obtained from the British Steel Corporation's
In-Plant Fines Group, The Japan Iron and Steel Federation, and the
Verein Deutscher Eisenhuttenleute (Germany). However, the spread in the
quantities of residues generated even in the same country is not
significantly smaller , as one can see in the tabulations within each
subchapter of this report, where not only the management and disposal
practices but also the quantities of residues arising are compared.
21
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Table 2-7 QUANTITIES OF POLLUTION CONTROL RESIDUES GENERATED
IN VARIOUS IRON AND STEELMAKING OPERATIONS
(kg of residue - dry basis - per ton of product)
Coking
Breeze
19-50
Other
0.5-1
Sinter-
ing
3-33
BF
7-55
BOF
8-35
OH
5-20
EAF
5-20
CC
2-25
Rolling
30-102a
BF = blast furnace
BOF = basic oxygen furnace
OH = open hearth furnace
EAF = electric arc furnace
CC = continuous casting
a Per ton of raw steel production
The total quantities of residues generated by the U.S. steel industry's
pollution control facilities in 1974 are shown in Table 2-8.
The total quantities of residues generated in the pollution control
facilities of the U.S. iron and steel industry were approximately 16.6
million tons (Mt) in 1974. Of this, almost 55%, or 9.1 Mt, was recycled
and 45%, or 7.5 Mt, dumped or "stored" for possible later reuse.
The major problem in recycling the presently dumped or "stored" residues
is the tramp element content (such as zinc and lead, or oil) of the
residues . The quantities recycled are discussed by subcategories
in Chapter III and in a special Section, 3.16, Recycling.
The cost of pollution control and disposal of the residues generated in
the iron and steel industry are not subjects of this study but can be
f , . ,(7,8,9) . (10,11,12)
found in government and other publications
22
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Table 2-8 ESTIMATES OF IRON AND STEEL MILL POLLUTION CONTROL
RESIDUES IN THE UNITED STATES IN 1974
(million tons/year)
1 . Coking
2. Sintering
3. BF (iron)
4. BF (Fe-Mn)
5. BOF
6. OH
7. EAF
8. Vacuum degassing
9. Continuous casting
10. Rolling
11. Pickling
12. Coating
13. Waste water plant
14 . Boilerhouse
TOTAL
Residue Arising
1.0
0.9
3.3
< 0.053
1.7
0.5
0.4
<0.05«
0.2
7.4
0.4
C 0.05
0.7
c
16.6
. Recycled
1.0
0.9
2.3
- a
0.4
0.1
0.05
- a
0.1
4.2
-
- a
-
c
9.1
Dumped
^0.05
<0.05
1.00
a
1.3b
0.4b
0.4b
a
0.1
3.2b
0.4b
- a
0.7b
c
7.5
a .Insufficient data
b Including "stocked" for possible later reuse.
c Negligible when low sulfur oil or gas is used,
23
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2.7 REFERENCES
1) Annual Statistical Report for 1974. American Iron and Steel
Institute, Washington, D. C., 1975.
2) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
3) Development Document for Proposed Effluent Limitations Guidelines
and New Source Performance Standards for Steelmaking. U.S.
Environmental Protection Agency, EPA 440/1-73/024, February 1974.
4) Executive Office of the President, Office of Management & Budget.
Standard Industrial Classification, 1972.
5) Pasztor, L., and Floyd, S. B., Jr. Pollution Abatement Residues
Arising in the Iron and Steel Industry. In: Proceedings of
3rd National Conference on Complete Water Reuse (Paper 13a),
Cincinnati, Ohio, June 27-30, 1976.
6) Pasztor, L. Problems of Resource Recovery in the Iron and Steel
Industry. In: Proceedings of the 4th Annual Industrial
Pollution Control Conference of WWEMA (Paper #L), Houston, Texas,
March 30-April 1, 1976.
7) Pollution Abatement Costs and Expenditures - 1973. U.S. Department
of Commerce, Bureau of the Census, MA-200(73)-2, Washington, D.C.,
1976.
8) Arthur G. McKee & Company (Cleveland, Ohio). (Report prepared
for the National Commission on Water Quality.)
9) Baker & Sloan, Inc. (Cambridge, Mass.). (Report prepared for the
U.S. Environmental Protection Agency.
10) Arthur D. Little, Inc. Steel and the Environment: A Cost Impact
Analysis - A Report to the American Iron and Steel Institute.
ALD, Inc., C-76482, May 1975.
11) Taishoff, E. The Impact of Environmental Controls. Steel Facts
72/2 (1972).
12) Agarwell, J. C., Flood, H. W., and Gilbert!, R. A. Preliminary
Economic Analyses of Pollution Control Systems in Metallurgical
Plants. J. of Metals, December 1974, pp. 7-17.
24
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CHAPTER III - POLLUTION ABATEMENT IN THE
IRON AND STEEL INDUSTRY CATEGORY, BY SUBCATEGORIES
The iron and steelmaking process is usually described as consisting of
four principal processing steps: (1) preparation of raw materials;
(2) raw iron manufacturing; (3) raw steel manufacturing, and
(4) finishing of steel products. This is one way in which the iron
and steelmaking process can be divided.
For the purposes of this report, however, a subcategorization of the
principal processing steps of the iron and steel industry category was
necessary. This approach was used not only to follow the previously
established subcategorization by EPA but also to more closely identify
the arising of the residues generated in the various pollution control
facilities. This chapter deals with the 13 principal iron and steel-
making subcategories from coking and sintering to rolling and other
finishing operations.
Three more sections or subcategories have been added: one deals with
joint waste water treatment plants, another with miscellaneous
operations (pig casting, machine and maintenance shops, etc.), and
a final section describing the progress and problems in the recycling
of pollution abatement residues.
25
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3.1 SUBCATEGORY: COKING
Coke, a primary constituent in the blast furnace charge, is the hard,
porous aggregate that remains after certain coals are heated to high
temperatures in the absence of air. In modern practice, this heating
is carried out in long, high but narrow chambers (for example, 3 meters
high by 10 meters long by 0.5 meters wide) which are combined in
groupings of 50 or more to form a battery. Each chamber is ported at the
top to receive the coal charge. Typically, the coal is chuted into the
ovens from larry cars which traverse the top of each battery. The ends
of each chamber or oven are closed by doors which are removed to
facilitate the discharge of the coke at the completion of the
carbonization cycle. Subsequently, the coke is quenched.
The ovens are formed of high-grade refractory brick and an intricate
arrangement of flues and ducts is built into the walls between chambers,
to assure uniform coking of the coal. Heat is supplied to the ovens
through these flues and ducts. A regenerative heating system is used and
each battery contains its own set of checker chambers which are used for
preheating the gases. The coke oven and blast furnace gases are normally
utilized as fuel.
Volatile constituents driven from the coal during the roughly 17-hour
coking cycle are withdrawn through ducting attached to the top end(s)
of the oven chambers. From here the gases and vapors are drawn into a
collecting main(s) where spray water (recycled flushing liquor) is used
to cool and convey the gases and condensed liquids to a by-product plant
where the gas is, in effect, cleaned in preparation for its subsequent
use as fuel throughout the plant.
The liquids from coking operations are generally designated as: ammonia
liquor, tar and light oil. These primary products are broken down in
the secondary operations of the by-product plant into their many
components in line with the internal or marketing needs.
26
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In 1974 54,707,597 tons of metallurgical coke was produced by the U.S.
iron and steel industry .
Almost all integrated steel mills contain by-product coking plants.
These operations are a major source of concern with regard to air and
water pollution potential. From the coking aspect,tthe following
procedures or phases are recognized as being historically dirty:
A. Charging - The placing of fine coal into hot ovens is the primary
(2)
source of pollution with the evolution of hydrocarbons, steam,
particulates, CO and H,,S.
B. Coking or Carbonization - A well-sealed oven will produce few, if any,
emissions during this conversion period. However, this depends on
good maintenance procedures, particularly with regard to the doors
and sealing of the charge ports.
C. Pushing - Emptying of the oven after firing is an inherently dusty
operation complicated at times by incomplete coking of the charge.
(2)
Phenol and cyanide releases are an additional problem
By-product operations are primarily concerned with the conversion of the
condensed, and volatile constituents from the coking operation into
marketable or useable products. Regardless of the sophistication of
this operation, process wastes always remain. These wastes are
troublesome from a disposal standpoint and efforts to make them less so
results in pollution control residues.
All but 2 of the 11 plants visited for this study had coking facilities.
These ranged in size and output from one battery of 75 ovens with a 1974
production of slightly under 400,000 tons to a seven battery, 500+ oven
installation with just under 3,000,000 tons for 1974. Five plants
reported on their efforts to reduce charging emissions. These included
smokeless larry cars on four of 16 batteries at three plants: a
stage-charging system on the one battery at one plant; an AISI larry
car on one of six batteries at another facility, and a coal preheat and
27
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steam charging installation on one of seven batteries at one plant.
The waste water effluents from the scrubbers on the smokeless larry
cars were, in all cases, discharged to the quench water circuits serving
those batteries and neither the quantities nor the chemical composition
of these wastes were reported.
The limiting of emissions during carbonization, as previously indicated,
depends primarily on good maintenance procedures. In our discussions
at the various plants, it was obvious that concerned personnel were
well aware of this and efforts were being made in this direction.
Only two batteries (one at each of two plants) are equipped with devices
designed specifically to alleviate pushing emissions. One of these
is a hood extending the length of the battery. A wet scrubber is
provided to clean the exhaust from this hood with a reported collection
of 0.12 kg of dry residue/ton of coke. The residue is combined with the
sump breeze from the quenching operation. The other collection system
consists of a hooded coke car also equipped with a wet scrubber which,
again, discharges its liquid wastes to the adjacent quench water circuit.
In this instance, exact figures as to the quantity of residue from the
push car collector were not available but an increase in sump collection
is noted in the following discussion on quench station residues.
The quench water circuits at all of the plants we visited were closed
loop with fresh water makeup and a sump to settle out suspended solids.
Four plants reported sump breeze collections in the 3.5 kg/ton of fired
coke to 9 kg/ton range. The latter figure is for the one battery
provided with the push car coke dust collector noted in the above
paragraph. The other batteries at the site that do not have charging or
pushing pollution control devices are listed as yielding only 5 kg of
sump residue per ton of coke. Most of the sump breeze is sold (larger
pieces, primarily) and used for soaking pit bottoms or in the sinter mix.
Only a small amount was delegated to stock.
28
-------
Only one plant reported a pollution control residue as the result of
their by-product operation. (All of the others considered their plant
effluents as process wastes.) This plant had a biological treatment
system (see Figure 3.1-1) that yielded 3.8 kg of lime-biomass residue
(filter cake - dry basis) per ton of coke. This residue was
landfilled. One other plant also had a biological treatment system
but it was discharging the liquid effluent from this plant into a
nearby stream. Consequently, no residue was reported, per se.
The chemical composition of coke breeze is usually between 80-90% C,
with the balance varying with the chemistry of the inorganic components
(ash) of the various coals used in the coking operations.
Because the coking pollution control residues are recycled (and,
therefore, no problem exists with the management and disposal of these
residues) no investigation was made either on the variation in chemistry
or in particle size of these residues.
In most coking operations the coke breeze (sometimes called "sump
breeze") originating in the coke-quenching operation is mixed with the
coke breeze obtained in screening and dedusting operations. The total
quantities of coke breeze generated in all of the operations are
usually reported by companies and institutions. The quantities of
strictly pollution control mixtures are reported in Table 3.1-1 and are
compared with the total quantities of coke breeze collected in the
coking operations.
The quantity of total coke breeze collected in the U.S. is approximately
36 kg/ton to 57 kg/ton of coke produced. Another respected
/•o\
source gives a range of 50-100 kg/ton of coke produced. Since
total coke breeze figures are usually given in England * ' , Germany
and Japan' ' as well as in the U.S., and because various size fractions
(including the pollution control residues) may be included or excluded
in the coke breeze figures, a direct comparison is not possible.
29
-------
Aeration Basins
To final effluent
control pond
Balancing
Tank
Clarifier
Clarifier
Lime
Sludge
Clarifier
Ammonia
Stills
Drum
Filtets
Oil & Tar
Separation
Tank
Lime Sludge
Contaminated Waters
and Flushing Liquor
from Coke Works
Figure 3.1-1 BIOLOGICAL COKE WASTE TREATMENT PLANT SCHEMATIC
30
-------
Therefore, the figures have to be looked at, taking this loose
definition of coke breeze into consideration.
Table 3.1-1
QUANTITIES OF COKE BREEZE AND COKING
BOLLUTION CONTROL RESIDUES GENERATED
IN STEEL MILLS
(kg/ton o,f coke produced)
United States
England
Germany
Japan
Totalh
36^
30 - 40(4)
25 - 40(5)
^•OTt.
Strictly Pollution
Control Residues^
3.5 - 9
1.7 - 8
NA
10 - 20(6)
a Includes unloading, charging, coking cycle, discharge
and quenching.
b Includes screening coke breeze and pollution control
residues.
The OECD, ED reported ' all the airborne and waterborne residues
generated in coke operations based on information supplied by six
European countries and the U.S., Japan and Canada (Table 3.1-2).
The pollution control facilities on the coking operations are essentially
the same in Europe and Japan as in the U.S. For the dedusting during
the charging and coke-pushing cycles, only experimental setups are in
operation; however, everywhere (as it is in the U.S.) the trend is
toward dedusting of these operations. The clarification and recovery of
coke breeze from the quenching waters is also similar. The coke breeze
and the residues are recycled mostly through the sintering operation
although in some cases, it is returned to the coal piles, used in
soaking pit bottoms, or, occasionally, briquetted and used for various
purposes.
31
-------
The only major difference in the pollution control and residue
generation of the coking operations is the trend towards complete
control of the SCL or H S emissions in Japan. All three huge integrated
steel mills we visited in Japan had coking off-gas desulfurization
units. All of these operations, however, convert the sulfur in the
off-gases to commercial elemental sulfur, ammonium sulfate, gypsum or
sulfuric acid, in place of producing residues. The processes used in
these desulfurization operations are the Diatnox (developed by
Mitsubishi Chemical Industries, Ltd.), the Ammonia Takahax Wet
Oxidation method (by Nippon Steel Chemical Company), and the Fumax
process (by Sumimoto Chemical Engineering Company). In the U.S. (while
not generally accepted yet) the Karl Still, Koppers,Glaus and other
processes are used for the same purpose. These are similar to or the
same processes also used in Europe.
32
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Table 3.1-2 RAW RESIDUAL LOADS ASSOCIATED WITH COKE
MANUFACTURING OPERATIONS
Type of Discharge
Raw Residual Load
kg/ton of coke
Airborne residuals
Particulates
Sulfur dioxide
Hydrocarbons (tar)
Hydrogen sulphide
Hydrogen cyanide
30.0
0.2
4.0
0.1
0.1
50.0
1.0
8.0
0.8
0.6
Waterborne residuals
(effluent flow, lit. /ton)
Ammonia
Phenol
Cyanide
Sulphide
Oil and grease
Suspended solids
(pH)
(730)
1.5
0.3
0.15
0.9
0.3
0.09
0.07
(6 - 9)
33
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3.1 REFERENCES - COKING
1) Annual Statistical Report, 1974. American Iron and Steel Institute,
Washington, D. C., 1975-
2) Barnes, T. M., Hoffmann, A. 0., and Lownie, H. W. First Report
on Evaluation of Process Alternatives to Improve Control of Air
Pollution for Production of Coke. Battelle Memorial Institute
Report to Division of Process Control Engineering, NAPCA,
January 1970.
3) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
4) Private communication from British Steel Corporation.
5) Private communication from Verein Deutscher Eisenhuttenleute.
6) Prviate communication from The Japan Iron and Steel Federation.
7) Organization for Economic Cooperation and Development.
Environment Directorate PCC/AEU/ENV/75.2 (Preliminary Draft),
Paris, 1975.
8) Trace Pollutant Emissions from the Processing of Metallic Ores.
U.S. Environmental Protection Agency, EPA-6502-74-115, October
1974.
9) Speight, G. E. Best Practical Means in the Iron and Steel
Industry. The Chemical Engineer, March 1973, pp. 132-139.
10) U.S. Bureau of Mines. Distribution of Oven and Beehive Coke and
Breeze in 1974. Mineral Industry Surveys, U.S. Department of
the Interior, Washington, D. C., March 1976.
34
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3.2 SUBCATEGORY: SINTERING
Sinter and pellets are major, relatively new industrial constituents in
modern blast furnace practice. Both provide iron units and both have
improved furnace operations largely because of their closely controlled
sizing. The measure of their importance is che fact that almost three
times as much agglomerated material (sinter, pellets, etc.) was used
for charge material in making iron in 1974 as raw iron ore '
(approximately 117 million tons of agglomerated products vs. 41 million
tons of raw iron ore).
Since pellet production is almost exclusively tied in with mining and
ore concentrating operations far removed from basic iron and steel-
making facilities, pellet plants did not fall within the scope of this
study. Sintering, on the other hand, is principally an integral or
closely associated steel plant operation since many of the base materials
for sinter are found in the integrated steel mills.
Sinter is a hard, porous agglomerate formed by fusing a wide variety
of fines together on what is known as a sinter machine or strand.
The raw sinter mix can vary considerably but may typically include
naturally fine ore, iron concentrates, ore fines from screening
operations, BF flue dust and sludge as well as other iron-bearing
residues from plant operations. The addition of BF fluxing agents,
to make "fluxed" sinter, is becoming increasingly popular. These
materials are blended with a fuel (coke breeze or coal fines) and
return sinter fines in a mixing drum or disc. The latter results in
the "granulation" of the mix so that the feed to the sinter machine
consists of a wide range of odd-sized and shaped granules resulting
in the formation of a permeable bed.
The sinter machine itself is, in effect, an endless moving belt with
the conditioned mix placed on the feed end and the finished hot sinter
coming off the opposite or discharge end. The belt consists of a
large number of pallets containing high temperature grates which support
35
-------
the bed. Rolls on the sides of these pallets ride on side rails and
permit the pallets to be pushed along. A firing hood on the head end
of the machine ignites the fuel in the top of the bed and air is drawn
through the material and grates as the pallets move slowly down the
machine. With a properly proportioned fuel addition, the flame front
developed from the ignited firing progresses down through the bed.
When this front reaches the bottom of the material, the finished sinter
is ready for discharge. In the latest machines, a thin hearth layer
of fired sinter is deposited on the grates prior to the raw sinter mix.
This serves to lower grate temperatures and prevent damage to the grate
bars at burn-through.
Temperatures developed during sinter firing are such that fusion
of the bed takes place and large, porous sintered masses are formed.
These masses are given an initial crushing and sizing as they leave
the machine. The still-hot sinter then goes to a cooling station and
then to additional crushing and screening operations to yield the final
sized product. Forced air coolers are normally used although water
quenching was employed at two of the plants we visited.
Sinter machines vary widely in size and capacity. With the recent
adoption of higher suction (increased air flows and pressure drops
across the bed) the capacity of the machines expressed as sinter output
per square foot of grate area per unit of time continues to increase.
This, combined with technological advances in grate and machine
design, has resulted in single strands with a rated annual output
of over 4,000,000 tons of sinter per year in contrast to earlier
strand ratings of 500,000 tons per year or less.
The seven plants we visited with sintering operations contained a total
of 17 strands with variations of from one to six machines per plant.
1974 sinter production from these facilities was a total of 12,000,000
tons and ran from slightly more than 500,000 tons at two of the plants
to roughly 2,500,000 tons at one plant. Total industry-wide production
36
-------
for the year was 40,769,185 tons (including some briquettes and
nodules)(^).
Sinter operations are inherently dusty. Particulates, as well as
combustion products, become entrained in the gas stream (windbox
exhaust) as it is drawn through the sinter bed and substantial
quantities of airborne dust are generated from the cooling, screening
and sizing of the sinter ac the discharge end of the machine. In the
more recent sinter plant installations and those older plants where
pollution abatement equipment have been added, both wet and dry collection
systems are used to clean the windbox exhaust in addition to the
basic primary mechanical collectors with which these machines are
equipped. Venturi scrubbers are the choice for the wet systems and
either electrostatic precipitators or baghouses for the dry. Where
collection equipment is used on the discharge end operations, dry
collectors are the usual choice including high efficiency cyclones
and baghouses.
The following tables outline our findings in those plants we visited
with regard to the collection equipment they use:
"Windbox" Exhaust Control "Discharge End" Emission .Control
No. of Plants No., of Plants
Dry ESP 2 Mechanical 2
Mechanical only 2 Baghouses 2
Baghouse 1 Scrubbers 1
Scrubber 1 Water quench 2
Dry ESP & scrubber 1
The water circuit for the one windbox exhaust gas scrubber shown
above is closed loop with a bleed to a secondary treatment system. The
discharge end scrubber water is once-through with pariculate removed in
a joint treatment facility. In the two water quench application, the
water used to quench the hot sinter (rather than air or forced draft
37
-------
cooling) is recycled with a blowdown to settling ponds for sludge
removal. One of these two plants also has a mechanical collector on
the discharge end of one of their four sinter machines.
We were not able to obtain as much factual information on the quantity
and nature of sinter plant emissions from our plant visits as we
would have liked, because virtually all of the collected dusts and
sludges are recycled directly to the sinter strand, usually without
weighing or chemical analysis. Since the sintering operation
includes a built-in recycle system (for hot and cold return fines),
the recycling of these emission control residues poses no major
problem. The data we were able to develop with regard to the
chemical makeup of the collected residues of the plants is given in
Tables 3.2-1 and 3.2-2. With the exception of the high alkali
content in the windbox dust from plant G there are no indicated
chemical reasons why recycling is not practical. Plant G does,
however, landfill their windbox dust for the afore-mentioned reason.
Table 3.2-3 lists the chemical analyses of sinter dust as reported
by several literature sources. Table 3.2-4 gives sizing data on
our samples indicating great variation in the size of the particles
of the sintering residues. Data obtained from the literature
indicate the same variation in particle mix distribution. A British
source reports similar data as our Plant E for ESP dust (i.e.,
19-41%) while others report 61%(2)' 84%(4) and 98.1%(3) in the -325
mesh range.
The reason for the little substantive data gathered on the quantities
of dusts and sludges generated at these plants is that these
residues have almost without exception been successfully absorbed into
the sinter process and are no longer considered as troublesome wastes.
Consequently, the pollution control personnel we had contact
with had little knowledge,or real concern with, specifics on this
38
-------
Table 3.2-1 ANALYSIS OF SINTERING "WINDBOX" END POLLUTION
CO
CO
CONTROL RESIDUES
(% dry basis)
a Results obtained from the steel company
b Electrostatic Precipitator dust
c • Contained also 1-2% oil
d Contained also 0.36% oil
Plant
A
if
E
C
I
Sample
Sludge 1
Sludge 2
S'ludge
Dust Ia
Dust 2b
Dnstd
Sludge
Total Fe
57.0
51.5
20.3
52.9
50.1
22.5
34.1
C
5.4
13.8
NA
7.9
6.1
6.6
Zn
0.02
0.02
NA
0.02
0.01
Pb
0.04
0.06
NA
0.04
0.02
K20
0.17
0.27
NA
0.57
0.36
10.4
3.8
A120,
2.4
2.1
3.0
1.7
1.5
1.04
5.9
Sa
0.0-*
0.01
NA
0.02
0.02
S102
5.2
4.7
19.0
5.3
5.2
CaO
KgO
j
0.21
0.12
22.0
; 4.3
5.3
16.2
12.3
0.15
0.09
11.0
2.0
2.7
4.6
3.0
S
0.16
0.27
0.29
0.19
1.2
0.7
-------
Table 3.2-2 ANALYSIS OF SINTERING "DISCHARGE" END POLLUTION
CONTROL RESIDUES
(% dry basis)
Plants
D*
E
ca
Sample
b
Sludge 1
Sludge b 2
Dust c 1
Dust ° 2
Dust C 3
Total Fe
21.7
23.2
37.5
18.4
18.4
18.5
C
Na
8.0
8.6
NA
NA
NA
Zn
NA
0.01
0.01
NA
NA
NA
Pb
NA
0.01
0.02
NA
NA
NA
k2o
NA
0.23
0.29
NA
NA
NA
A1203
NA
1.6
2.8
1.2
1.2
1.35
Sn
NA
1.7
0.04
NA
NA
NA
Si02
10.0
5.9
6.5
6.20
5.85
5.96
CaO
31.0
27.4
13.8
30.4
30.2
29.7
MgO
30.0
2.6
2.0
15.7
14.5
14.9
.p-
o
a Results obtained from the steel company
b From hot quench operation
c Baghouse dust
-------
Table 3.2-3 ANALYSIS OF SINTER PLANT DUST (FROM LITERATURE)
(% dry basis)
Ref .
2
3
4
Tot . Fe
43.5
45.0
45.3
C
3.5
.8-5
3.2
Zn
0.03
0-3
0.15
Pb
NA
0-.05
0.05
K20
NA
NA
NA
A1203
3.5
1.9-
-3.8
3.2
Si02
8.6
NA
9.3
CaO
15.5
5.6-
-7.0
7.9
MgO
1.5
NA
0.7
S
0.2
3-4
0.6
Ti02
0.7
NA
0.5
Ni
NA
0-
7
NA
-------
Table 3.2-4 PARTICLE SIZE ANALYSES OF SINTER PLANT
RESIDUES
(Cumulative Percent Retained on Screen)
Screen
8 mesh
16 mesh
30 mesh
50 mesh
100 mesh
200 mesh
325 mesh
325 mesh°
20 micron
10 micron
Plant Aa
Windbox
Scrubber Sludge
Simple 1
-
-
-
T
1.5%
18.4
37.3
27.5
52.6
64.1
Sample 2
-
-
0.1%
0.5
5.5
25.7
42.0
25.5
48.4
61.2
Plant E
ESP' Dust
Sample 1
-
0.7%
2.8
8.1
21.5
43.8
60.4
59.4
79.1
84.3
Sample 2
0.2%
2.5
13.0
24.7
40.2
64.6
79.7
81.4
-
-
Cooling ,
Water__Sludge
Sample 1
-
.-
-
-
-
-
-
3.4%
22.7
44.6
Sample 2
-
-
-
-
-
-
-
1.9%
17.7
39.1
a Plant A secured this sample from their companion operation.
b Settled sludge from blowdown of closed loop water cooling circuit.
c Separate screening of another portion of sample.
42
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material. The information we were able to gather as to types,
quantities and dispostion are in Table 3.2-5.
An EPA'°' source gives a dust output for sintering operations as
about 21 kg/ton. In the U. S. plants which we visited 3-25 kg
of sinter residues are generated/ton of sinter produced; in European
plants 15-30 (in England 19(5), in Germany 15-30) and in Japan,
13-20 kg were reported, fhe OECD, ED report(-7) estimates the
airborne residues to be between 15-25 kg/ton and the suspended
solids 8.3 kg/ton (Table 3.2-6).
As in the U.S., the sintering pollution control residues are also
recycled in Europe and in Japan. However, in Europe and in Japan
when the Zn and Pb content of the residues is getting high 2tue
to Zn and Pb accumulation, the residues are recycled through special
processes such as the SL/RN or Waelz processes. In these processes,
the Zn and Pb are volatilization-separated from the iron-rich
matrix at elevated temperatures in a reducing atmosphere. Subsequently
the Zn and Pb is recovered from the separated Zn and Pb-rich residues.
For details on these recovery processes, see Section 3.16,
Recycling.
In two mills of the three we visited in Japan, SD^ as well as
particulate matter is removed from the sinter off-gases. At one of
the plants the end product of the desulfurization on two sintering
units is high-purity gypsum. At another plant (on one unit) the end
products of desulfurization are either ammonium sulfate crystals
or gypsum, both regarded as high-quality saleable commercial by-
products.
While the quantities of these by-products vary depending on the
sulfur content of the sintered materials, they are not regarded as
pollution control residues since they are sold as commercially
valuable products.
43
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Table 3.2-5 TYPES AND QUANTITIES OF RESIDUES GENERATED IN U.S.
SINTERING OPERATIONS AND THEIR DISPOSAL
Plant
I
J
G
K
F
D
E
Residue
Dust
X
X
X
X
X
X
X
Sludge
X
Joint
-
_
-
b
3T
Residue Quantities
Dust
NA
NA
24.5 kg/ ton
2.9 kg/ton a
5 kg/ton
NA
6.2 kg/ton
Sludge
NA
NA
-
-
-
.95 kg /ton
Disposition
Recycle - sinter
Recycle - sinter
80% recycle -sinter
20% landfill
Recycle - sinter
Recycle - sinter
Recycle - sinter
Dust - sinter
Sludge - stock
a Baghouse portion - no figure available on cyclone residue
b Sludge from hot quench operation
-------
Table 3.2-6 RAW RESIDUAL LOADS ASSOCIATED WITH SINTER
PLANT OPERATIONS
Type of Discharge
Raw Residual
Load
(kg/ton of sinter)
Airborne residuals
Particulates
Sulfur dioxide
15.0 - 25.0
1.0 - 12.0
Waterborne residuals
(Wet particulate control system)
(Effluent flow, lit./ton)
Suspended solids
Oil and grease
Sulphide
Fluoride
(pH)
(1,043)
8.3
0.6
0.2
0.03
(8 - 10)
45
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3.2 REFERENCES - SINTERING
1) Annual Statistical Report for 1974. American Iron and Steel
Institute, Washington, D. C., 1975.
2) Saito, Y. Direct Reduction Process for Recycling Steel Plant
Waste Fines. In: Proceedings of Ironmaking Conference, Vol. 34,
ISS-AIME, Toronto, 1975.
3) Anonymous. Recycling of Steel Plant Waste Materials. Steel
Research, 1974, British Steel Corporation, 1975-
4) Yatsunami, K. Outline of SL/RN Reduced Pellet Plant at NKK's
Fukuyama Works in Japan. Lurgi, West Germany, 1975.
5) Speight, G. E. Best Practical Means in the Iron and Steel
Industry. The Chemical Engineer, March 1973, pp. 132-138.
6) Varga, J., Jr., and Lonnie, H. W. A Final Technological Report
on a Systems Analysis Study of the Integrated Iron and Steel
Industry. Battelle Memorial Institute, Columbus, Ohio. '
7) Organization for Economic Cooperation and Development.
Environment Directorate, PCC/AEU/ENV/75.2 (Preliminary Draft),
Paris, 1975.
8) EPA. Trace Pollutant Emissions from the Processing of Metallic
Ores. EPA 650/2-74-115, October 1974.
9) Pengidore, D. A. Sinter Plant Windbox Gas Recirculation System
Demonstration. EPA 600/2-75-014, August 1975.
10) Varga, J., Jr. Control of Reclamation (Sinter) Plant Emissions
Using Electrostatic Precipitators. Battelle Memorial Institute,
Columbus, Ohio, January 1976.
46
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3.3 SUBCATEGORY: BLAST FURNACE (IRON)
The blast furnace (BF), the basic unit for the production of iron, has an
evolutionary history dating back some centuries. However, it has only
been during the last hundred years that the rapid strides have taken
place which make these units the highly efficient mass producers of
this essential metal that they are today. In capsule form, the blast
furnace reduces an iron-bearing charge to iron and a gangue slag. Coke,
as heat source and reducing agent in the charge, air as hot blast, and
limestone or dolomite as fluxes, are the essential ingredients which,
with time, produce the transformation of the raw materials to iron.
The furnace charge and firing practice vary considerably throughout the
industry. The choice of raw materials, their physical and chemical
make-up, and the iron grade desired are but a few of the reasons for
this. The U.S. steel industry in 1974 (when 95,909,000 tons of iron
were produced ) consumed the following materials per ton of iron
produced in the blast furnaces:
Ore and agglomerates 1.618 tons
Scrap ' 0.031 tons
Flux materials 0.244 tons
Cinder, scale, etc. 0.048 tons
Coke 0.609 tons
The ore and agglomerates are the main iron-bearing components.
Agglomerates are normally pellet and/or sinter although some nodules and
briquettes are also used. Pellets are produced in conjunction with
mining and concentrating operations and, like the ores, are shipped to
the mill complexes by boat or rail. Sinter, on the other hand, is a
product of in-plant or closely associated operations since it is the
vehicle by which many of the plant fines and waste residues, including
those resulting from pollution abatement procedures, are effectively
-, j
recycled
47
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The blast furnace is a tall circular refractory-lined steel shell with
a working height of up to 30 m (100 ft.) and a hearth diameter
on the bottom of from 3-12.2 m (10 to over 30 ft.) in diameter in
the U.S. and up to 14.6 m (47.4 ft.) in Japan and Europe.
The charge is inserted at the top of the shell in a rather unique manner
which assures the sealing of the furnace and the collection of the
off-gases. As the burden moves down the furnace column it is subjected
to heat supplied by the burning of the coke in the presence of hot fuel-
enriched blast air introduced through a series of tuyeres near the
bottom. Carbon monoxide formed by the burning of the coke is the
primary reactant reducing the iron ore and, in general, the iron oxides
to metallic iron in the charge. The fluxing agents permit the forming
of a slag at operating temperatures enabling the gangue (largely silica
and alumina) to be effectively carried out of the furnace in a hot and
liquid slag form.
Smelting of the charge yields iron and slag which are periodically
removed from the bottom of the furnace and a continuous discharge of
blast furnace gas out of the top. In the largest furnaces in Japan and
Europe, the iron and slag is essentially continously removed.
Most of the iron (about 90%) is retained in liquid form for subsequent
refining into steel with a small amount going directly to associated
foundaries. The balance is cast into pigs for convenience in handling
and later remelting in cupolas or similar furnaces in the casting
industry. The hot molten slag is normally solidified with the help of
water and combed for entramped residual metal before disposal or reuse.
Because of their heating value, the large volumes of blast furnace
off-gases are used within the plant as an important fuel.
Blast furnace sizing varies considerably, the more modern units generally
being of the larger capacity. The newest and largest furnaces in the
U.S. can produce 4,500-8,000 tons of molten iron daily, and at top
operating levels can reduce a charge to metal in less than six hours.
48
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The annual capacity of the largest U.S. unit already in operation is
approaching 2 million tons; the largest Japanese and European blast
furnaces have a 4 million tons/year capacity. Of the plants we
visited, the number of furnaces per plant varied from 1 to 8 with a
total number of 42, although all of these furnaces were not in
operation. The following table gives the range of iron production
capabilities for these mills:
Work's Iron Capacity
(million tons /year)
<0.5
0.5 - 1.0
1.0 - 1.5
1.5 - 2.0
2.0 - 3.0
3.0 - 4.0
>4.0
Number of
Plants
None
2
1
None
4
1
2
The AISI Annual Statistical Report lists 135 of the 197 American
furnaces as in blast at the start of 1975.
CD
Unlike some of the steel refining steps to follow, BF smelting itself
is an inherently non-polluting operation from a particulate standpoint.
The furnace is sealed and the top gases are collected for further use
as an in-plant fuel or burned before release to the atmosphere.
Ahead of the furnace, stacking, blending' and materials-handling phases
can be and are a source of air contamination, but these discharges
are of a comparatively minor nature in the overall picture and most
plants make a reasonable effort to control these dusts within the
confines of the plant. The same holds true for the periodic tapping
and teeming operations when the iron and slag are removed from the
furnace. In the long run, however, even these emissions will be better
controlled (not so much from the particulate standpoint but rather
because of their gaseous constituents which represent possible health
49
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hazards to operating personnel), to comply with the air pollution
control regulations.
At present, the only pollution abatement residues arising from BF
operations are those associated with the cleaning of the off-gases to
make them suitable as an in-house fuel. The quantity of these gases is
(2)
quite significant in that 4,920 pounds (or roughly 63,500 scf ) are
generated for each ton of molten iron. The cleaned gases, with their
2
high CO content (about 25%) and resultant heat value of 75-90 BTU/ft. ,
are used primarily as reheat for the stoves and for a number of other
secondary applications within the plant.
The standard industry approach to BF gas cleaning is to use a dual
processing procedure. The first or primary phase yields a dry residue
while the second (which may vary considerably in sophistication) results
in a dust-ladened water slurry. All furnaces are equipped with dust
catchers as the primary or dry dust-collecting source. These units
are large brick-lined chambers which, by virtue of an increasing
volume and reversal in gas stream direction, cause the heavier entrapped
particles to settle out. Only one of the plants we visited reported
an additional dust source from one bank of furnaces. Here, that
portion of the gas intended for boiler firing was passed through
multiclones after the dust catchers with no subsequent processing.
The ten plants we visited had a total of twelve BF shops (two plants
had two separate BF sections). Eight of these twelve installations
used scrubbers (largely venturi) as the wet phase of their dust
removal systems. The four other plants utilized wet electrostatic
precipitators in conjunction with washers and/or scrubbers for final
processing. One of the eight had precipitators in the line but was not
using them, and another followed their Venturis with disintegrators.
The rather dilute wet cleaning effluents are first sent to thickeners
or clarifiers for an intermediate concentration of the solids, and then
50
-------
on to filters or sludge basins for final thickening. Eight plants we
observed used vacuum filters and three, sludge basins. At this stage,
the sludge or filter cake has a solids content in the 75-80% range
at which level it can be reasonably handled by trucking.
Closed loop treatment of the process waters (both cooling and gas
cleaning) for blast furnace shops are gaining increasing popularity,
with four of the eleven shops now using this approach and several
others either in the installation stage or actively considering
recycling of water at the time of our visit. All of the closed loop
circulating systems utilize a bleed to balance their loops, and all
have a cooling tower in the circuit. Chemical additives to facilitate
settling or control contaminants are used by one half of the plants,
and joint treatment facilities in two cases.
The chemical makeup of the dust and sludge from these pollution
abatement procedures can vary widely from plant to plant, and even
within a plant with respect to time. Obviously, changes in the
chemical composition or physical consistency of the charge materials
and their proportions, firing practice and the grade of iron being
produced will have an effect on the amount and composition of the
entrained solids and gaseous products carried out at the top of the
furnace. Tables 3.3-1 lists the results of our chemical analyses of
the dust and sludge samples collected for this study.
The main constituents of the blast furnace residues are iron and carbon,
The total iron content of the samples we have analyzed varied between
16.8% and 54% while the carbon content varied between 17.3% and 53%.
In most cases, the sum of Fe and C was between 50-75%, making the
recycling of these residues attractive.
51
-------
Table 3.3-1 CHEMICAL
ANALYSES OF BLAST FURNACE RESIDUES - DUST
(weight %)
PART 1
Plant
C
E
F
H
I
L
Sample
1
2
3
4
1
2
T
J.
2
1
2
3
4
1
2
3
4
1
2
3
4
Fe
34.4
38.2
36.2
31.4
31.3
29.0
54.0
49.4
30.7
26.7
35.6
25.8
20.8
20.0
16.8
20.7
46.8
29.8
37.6
20.4
C
30.4
28.5
32.4
31.5
36.1
34.4
17.3
20.3
49.3
46.7
44.8
50.7
32.2
37.4
43.7
: 28.7
20.0
46.7
37.6
53.6
S
0.28
0.27
0.14
0.18
0.39
0.36
0.33-
0.42
0.16
0.21
0.31
0.34
0.29
0.75
0.10
0.35
0.23
0.57
0.63
0.66
Pb
0.01
0.01
0.01
0.01
0.02
0.03
0.06
0.08
0.03
0.02
0.03
0.02
0.01
0.01
0.01
0.01
0.15
0.09
0.05
0.09
Sn
0.01
0.01
0.02
0.04
0.03
<0.01
0.04
0.04
0.02
0.01
0.02
<0.01
0.04
0.04
0.04
0.04
0.02
CO. 01
0.03
0.04
Zn
0.09
0.09
0.09
0.07
0.05
0.12
0.21
0.17
0.01
0.02
0.03
0.02
0.01
0.01
0.01
0.02
0.02
0.02
0.02
0.02
Mn
0.15
0.12
0.06
0.14
0.16
0.11
0.04
0.04
0.06
0.08
0.06
0.04
1.52
0.42
0.77
1.02
0.20
0.18
0.15
0.17
1
0.05
0.08
0.07
0.10
0.04
0.05
0.04
0.09
0.11
0.13
0.11
0.08
0.11
0.01
0.08
0.07
0.15
0.33
0.51
0.22
K2°
2.4
2.3
2.7
4.5
2.6
1.6
0.40
1.2
1.0
r.e
1.3
1.0
0.63
0.02
0.66
0.80
1.8
2.7
2.. 5
3.0
A12°3
3.2
5.0
2.0
5.4
1.7
1.7
1.1
1.5
4.8
6.1
5.6
0.8
2.4
2.4
2.5
1.7
6.7
7.6
2.4
7.6
CaO
4.6
5.1
4.2
5.4
3.0
2.4
1.8
6.0
3.2
5.4
3.4
2.7
8.7
7,1
7.2
8.2
3.7
8.9
9.3
11.0
MgO
2.8
2.9
2.2
3.0
1.1
1.2
2.4
3.1
1.4
1.8
1.5
0.65
2.5
1.9
2.2
2.2
2.2
2.1
2.1
2.6
sio2
. 7.6
5.2
:
5.4
5.4
11.1
*
7.2
As
<0.02
<0.02
0.02
<0.02
CO. 02
<0.02
Sb
<0.01
<0.01
•
0.01
<0.01
<0.01
<0.01
Se
<0.01
< 0.01
0.01
<0,.01
<0.01
<0.01
en,
to
-------
Table 3.3-1 CHEMICAL ANALYSES OF BLAST' FURNACE RESIDUES - SLUDGES
(weight %)
PART 2
Plant
C
D
E
F
I
M
Sample
1
2
3
4
1
1
2
1
2
1
2
3
4
i^
2
O
4
Fe
29.4
26.5
25.6
27.2
21.8
C
29.3
27.7
28.0
29.8
40.9
40.7
43.0
39.6
38.9
30.3
30.2
30.4
24.7
32.5
28.5
27.5
35.6
24.3
21.1
18.3
18.9
30.2
31.4
34.3
40.5
32.5
32.. 3
35.1
20.9
S
0.47
0.45
0.44
0.19
0.25
0.46
0.46
0.78
0.94
0.25
0.31
0.26
0.68
0.63
0.86
0.93
1.01
Pb
0.09
0.09
0.13
0.11
0.10
0.19
0.13
,092
1.02
0.05
0.04
0.05
0.04
0.05
0.06
0.06
0.07
1
Sn
0.01
O.Oi
<0.01
•iO.Ol
O.Q&
O.C2
0-.03
0.05
0.04
0.03
0.02
0.03
0.02
0.01
0.01
0.03
0.03
Zn
1.11
0.50
0.86
1.04
1.6
0.26
0.38
2.1
2.6
0.04
0.06
0.06
0.07
0.08
0.14
0.12
0.11
Mn
0.06
0.09
0.14
0.13
0.07
0.17
0.10
O.C1
0.02
0.26
0.17
0.29
0.10
0.15
0.09
0.06
0.17
Na2°
0.07
0.08
0.07
0.05
0.11
0.04
0.04
0.08
0.09
0.03
0.04
0.04
0.03
0.08
0.03
0.07
0.04
V
1.6
1.9
1.3
1.1
1.9
1.2
0.87
0.65
0.92
0.41
0.60.
0.49
0.48
0.48
1.2
0.69
0.61
A120,
3.6
4.7
4.0
3.0
2.6
3.1
2:1
0.30
0.28
1.7
2.0
2.2
2.1
1.8
2.3
2.0
2.2
CaO
5.3
4.4
5.0
s:o
3.2
3.2
2.8
4.0
3.5
5.6
5.1
4.0
4.7
4.7
6.3.
6.8
8.2
MgO
2.5
2.4
3.0
2.7
1.8
1.2
0.86
2.3
2.2
2.0
1.8
1.5
1.5
1.2
1.7
1.8
1.9
SiO?
9.3
9.7
6.2
6.5
7.8
7.5
As
-CO. 02
<0.02
<0.02
•40.02
4,0.02
1
<0.02
Sb
<0.0l
,£0.01
<-o.oi
£0.01
<0.01
<0.01
Se
^0.01
<.0.01
<0.01
0.01
0.01
0.01
en
CO!
-------
CJ1
Table 3.3-2 CHEMICAL ANALYSES 0? BLAST FURNACE RESIDUES (FROM THE LITERATURE)
(% dry basis)
a
b
R-3f.
3a, d
3a, e
5b
6*
• 6a
7a-
8k. c
9a
10b
llb
12.b
12a
Fe
20.0/
49.9
5.9/
43
45
28.6
32.2
27.0
27.5
23.6
40. 2/
61.0
20.07
25.0
33.6
31.5
12a ! 40.0
123 ! 51.0
13a 1 50.0
14a i 2S.O
15a, c
43
C
6.67
50.0
1I.2/
33.9
5.5
40.8
38.5
21.4
S
-
-
4.6 -
0.3
0.2
-
17. S j 2.0
41.1
1.17
16.0
17.07
1S.O
23.3
30.0
10.0
10.3
11.0
25.4
2.5
0.22
0.087
0.3
—
-
0.7
0.2
0.3
0.2
0.54
3.4
Pb
0.0017
0.28
0.057
3.4
0.03
-
-
0.01
4.2
0.01
0.27
0.3
0.3
0.3
0.2
0.2
0.1
CO. 05
0.02
Sn
-
-
0.01
-
-
-
-
-
—
-
-
-
-
-
-
0.01
Zn
0.087
2.7
<:o.os/
11.5
0.2
0.54
0.45
0.05
9.5
0.08
0.27
0.3
9.07
10.5
0.7
0.7
0.8
0.8
0.8
0.15
0.4
Mr.
-
-
-
0.3
0.5
1.1
-
-
-
—
0.4
0.4
0.3
0.8
-
NagO
0.0957
0.52
<0.047
1.4
-
-
-
-
-
-
-
—
-
-
-
-
0.34
-
_
6.4
_
K20
0.487
1.82
0.307
5.4
-
-
-
-
-
-
-
—
0.5
0-.5
1.5
1.5
0.2
-
-
A12°3
-
-
6.2
3.0
2.5
-1.2
-
-
2.17
3.9
—
2.8
2.6
6.5
4.0
.-
13.2
3.8
1
CaO MgO
-
-
7.7
2.7
3.1
5.2
• -
-
3.17
4.6
—
7.5
7.0
6.0
6.0
4.5
9.4
-
-
-
-
0.7
0.7
2. .2
-
-
0.97
5.9
—
1.1
1.0
1.2
2.0
0.9
0.07
-
sio2
-
-
-
6.1
6.9
7.3
-
-
4.17
8.5
—
10.5
9.8
11.0
10.5
6.8
11.6
-
AS
-
-
0.007
-
-
-
-
-
—
~-
-
—
-
-
-
-
0.001
Dust
Slurry or sludge
C :
d
Average
Primary
Secondary
-------
Table 3.3-3 PARTICLE SIZE DISTRIBUTION OF BLAST FURNACE DUST & SLUDG2S
(Cumulative Percent Retained on Screen)
Screen
8 mesh
16 mesh
30 mesh
50 mesh
100 mesh
200 mesh
323 mesh
325 iaesha
20 ntcron
10 micron
Dusts at Plant
C
T
0.2%
,
^.2.2
22.7
67.1
89.5
94.6
97.6
98.5
99.2
E
-
0.7%
_2.4
12.5
46.5
77.3
89.8
86.6
97.2
98.1
F
-
T
0.6
5.9
25.4
66.0
94.0
93.5
98.8
99.4
H
0.2%
2.2
10.7
39.5
70.4
86.3
93.8
87.3
98.5
100.0
A-
-
0.1%
3.1
25.3
70.5
89.2
93.8
92.4
97.4
98.3
1
2.0%
• 3.3
8.2
34.9
69.0
91.0
95,9
95.5
98.8
99.8
Sludges at Plant
C
_
0.1%
0.2
5.4
38.0
56.0
33.9
57.9
66.3
D
-
-
-
T
4.5%
32.8
56.2
50.9
72.4
81.7
E
-
-
-
-
-
-
-
27.3%
52.2
70.0
F
-
-
-
-
-
-
-
30.0%
73.5
84.3
I
-
•-
-
1.0%
8.9
24U
38.7
33.5
78.5
88.5
M
-
-
-
-
-
-
38.2%
62.4
75.0
01
a Separate screening of another portion of sample.
-------
The tramp element content also varied, coincidentally: zinc between
0.1-2-6%, Pb from tr<
between 0.43 and 10.1
0.1-2-6%, Pb from trace to 1.02%, and the alkali (K20 + Na20) content
The chemical analyses of blast furnace dusts, sludges and slurries
reported in the literature show similar variation in composition
(Table 3.3-2).
As part of our study, we also ran size analyses on selected samples to
aid in determining how these materials might fit into possible
recycling processes that could be suggested for better utilization of
the potential represented by these waste residues. The particle size
distribution of the collected samples is presented in Table 3.3-3.
We found a wide variation from plant to plant in the quantities of
dusts and sludges (dry basis) collected (Table 3.3-4).
Table 3.3-4 BLAST FURNACE DUST AND SLUDGE (RESIDUES)
COLLECTED (1974)
'% OF IRON PRODUCTION
Plant
A
C
D
E
F
G
H
I
J
K
Dust %
2.8
2.3
3.4
3.4
1.8
0.8
1.5
0.8
1.0
0.7 ,
Weighted Avg. 1.55
Sludge %
0.8
0.2
1.1
0.5
1.0
1.3
1.2
1.6
2.8
0.8
1.37
Total %
3.6
2.5
4.5
3.9
2.8
2.1
2.8
2.4
3.8
1.6
2.9
56
-------
Six of the ten plants we visited with BF shops recycle all of their dusts
and sludges to sinter. The balance of the plants recycle or store their
dusts and landfill or stock their sludges (Table 3.3-5).
Table 3.3-5 BLAST FURNACE RESIDUES DISPOSITION - 1974
Plant
Disposition
Dust
Sludge
A
C
D
E
F
G
H
I
J
K
Recycle - sinter
Recycle - sinter
Recycle - sinter
Recycle - sinter
50% sale or sinter,
50% stock
Storage
Recycle - sinter
Recycle - sinter
Recycle - sinter
Recycle - sinter
Recycle - sinter
Recycle - sinter
Landfill
Recycle - sinter
Landfill
Landfill
Storage
Recycle - sinter
Recycle - sinter
Recycle - sinter
On a combined basis, the present disposition of the waste residues is as
follows: Weighted Averages
Recycle - sinter 77.4%
Landfill 13.3%
Stock 9.3%
The problems in recycling BF dusts and sludges are covered in Section
3.16, Recycling.
57
-------
The blast furnace off-gas cleaning practices are essentially the same in
England, Germany and Japan as in the U.S. In the works we visited in
these countries, "primary dusts" are usually collected in dust catchers
and sometimes in dry cyclones. Subsequently, the BF gases are further
cleaned in wet scrubbers and/or wet-type electrostatic precipitators.
In some operations in Germany, wet electrostatic
precipitators are used in combination with baghouses for the same
purpose.
The only major difference in the pollution control of the BF operations
between the U.S. and foreign plants visited is that the largest and
most modern blast furnaces in Japan also have tap hole, runner and
casthouse dedusting and degassing pollution control units. The
pollution control equipment used for these dedusting and degassing
operations &n older units include "wet rotocyclones," "dry air
tumblers," and baghouses.
The quantities of residues generated in the BF operations of the
different countries are presented in Table 3.3-6.
The residual loads associated with blast furnace operations based on
the OECD, ED 1975 study are given in Table 3.3-7.
Table 3.3-6 TYPICAL RANGES OF QUANTITIES OF RESIDUES
COLLECTED IN BF OPERATIONS BY COUNTRIES
(kg/ton dry basis)
United States 16-45 (33a)
England 25-50
Germany 20-55
Japan 7-35
a U.S. average in 1974'1'
58
-------
Table 3.3-7 RAW RESIDUAL LOADS ASSOCIATED WITH
BLAST FURNACE OPERATIONS
€17)
Type of Discharge
Raw Residual Load
(kg/ton of iron)
Airborne residuals
Particulates
0.2 - 1.6
Waterborne residuals
(effluent flow, lit./ton)
Ammonia
Phenol
Cyanide
Sulphide
Suspended solids
Fluoride
(pH)
(16,263)
0.2
0.02
0.03
0.3
26.0
0.08
(7 - 9)
The relatively lower residue quantities generated in the
ironmaking facilities are attributed by the Japanese experts ' to
two main differences in their BF operations: (1) the data supplied to
us were from some of the world's largest and most modern ironmaking
furnaces, and (2) the Japanese in the visited blast furnace operations
use higher sinter ratios than elsewhere in the world. The same
experts noted that when they have to switch from the high (i.e.. 80-90%)
sinter ratio (yielding a low 7-10 kg/ton residue) to a lower (e.g., 70%)
sinter ratio, the generated dust quantity increases to 15-16 kg/ton of
iron produced even in their large (11,000 tons/day) blast furnaces.
59
-------
While our study showed that an average of 77.4% of the total BF
pollution control residues generated in the U.S. are recycled, the
British Steel Corporation recycled about 50% of their residues (73%
of their dry and 22% of their wet residues). The Germans recycled
almost 94% and the Japanese snore than 90%, mainly through
sintering operations or "reduced pellet" operations.
60
-------
3.3 REFERENCES - BLAST FURNACE
1) Annual Statistical Report for 1974. American Iron and Steel
Institute,Washington, D. C., 1975.
2) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
3) British Steel Corporation. The Arising and Treatment of BSC
In-Plant Fines. Swinden Laboratories, Moorgate, Rotherham, 1975.
4) Private communication. Verein Deutscher Eisenhuttenleute.
5) Private communication. The Japan Iron and Steel Federation.
6) Saito, Yoshio. Direct Reduction Process for Recycling Steel Plant
Waste Fines. In: Ironmaking Proceedings, Vol. 34, ISS-AIME,
Toronto, 1975.
7) Goskel, M. A. Recovery of Iron, Zinc and Lead from BOF Dust and
Other Steel Plant By-Products. In1:! TSM-AIME Ironmaking
Proceedings, #30, 171, pp. 126-145.
8) Serbent, Harry (Lurgi), Maczek, Helmut (Berzelius Metallhutten
GmbH), and Rellermeyer, Heinrich (August Thyssen-Hutte).
Large Scale Test for the Treatment of BF Sludge and BOF Dust
According to the Waelz Process. AIME 34th Ironmaking Conference,
Toronto, April 15, 1975.
9) Barnard, P. G., et al. Recycling of Steelmaking Dusts. In:
Proceedings of 34rd Mineral Waste Utilization Symposium, Chicago,
1972, pp. 63-68.
10) George, H. D., and Boardman, E. B. The IMS Grangcold Process for
Agglomerating Steel Mill Waste Material. Grange Ore News,
October 1973, pp. 13-21.
11) Pi'naev, A. K., et al. Processing Sludge from Blast Furnace Gas
Cleaners. Steel USSR,^ Vol. 2 (11), 1972, pp. 859-861.
12) Brinn, D. G. A Survey of the Published Literature Dealing with
Steel Industry In-Plant Fines and Their Recycling. NTIS,
PB-236-359, August 1974.
13) Wetzel, R., and Meyer, G. Processing of Steel Works Dust and
Slurry. ISI Publication #139, Operation of Large BOF's, 1971,
pp. 44-51.
61
-------
3.3 REFERENCES (continued)
14) Dressel, W. M., et al. Pre-Reduced Pellets from Iron and
Steelmaking Wastes. AIME Annual Meeting, Preprint #73-B-82,
Chicago 1973, pp. 12.
15) British Steel Corporation. Recycling of Steel Plant Waste
Materials. Steel Research 1974, British Steel Corporation, 1975.
16) Private communication. Mizutani, H., Nippon Steel Corporation,
Kimitsu Works, 1976.
17) Organization for Economic Cooperation and Development Environment
Directorate, PCC/AEU/ENV/75.2 (Preliminary Draft), Paris, 1975.
62
-------
3.4 SUBCATEGORY: BLAST FURNACE (FERROMANGANESE)
This subcategory was established for this study because a previous
EPA study covered in a separate subcategory the ferromanganese
operations, and we also visited one plant that had a companion operation
where one blast furnace had been recently used for ferromanganese
production. Most ferroalloys are now made in electric furnaces.
Coincidentally, there were only two BF ferromanganese operations in
the U.S. in 1974(2).
The gas cleaning circuit used on this furnace consists of a dust
catcher, venturi scrubber and gas cleaning tower. The water circuit
is closed with the overflow from a 110' diameter thickener being
recycled to the scrubber and tower. Thickener underflow passes to a
vacuum filter. Fifty-seven kg (104 Ibs.) of dust and 114 kg (228
Ibs.) of dry sludge/ton of ferromanganese produced are collected. The
fresh filter cake contains roughly 35% moisture and is deposited in a
tar-lined (based) pit at their dump site. Collected dust is sold for
conversion to briquettes or pellets such as BOF feed.
Samples of the dust and sludge were provided and chemical and sieve
analyses were made. These data are presented in Tables 3.4-1 and
3.4-2. It should be kept in mind that these samples were collected
from storage or disposal piles that had been sitting for well over a
year since this furnace had not been in ferromanganese production since
1974.
In none of the plants visited in England, Germany and Japan did they
have blast furnace ferromanganese production nor did the Verein
Deutscher Eisenhuttenleute and the Japan Iron and Steel Federation harae
information available on the residues produced in these operations. In
general, we were informed that the quantities generated in BF farro-
manganese production are very small and negligible when compared with
the quantities arising in other types of pollution control operations
of the steel mills. Even when residues generated in electric arc
63
-------
Table 3.4-1 CHEMICAL ANALYSES OF BF FERROMANGANESE DUST & SLUDGE
(% dry basis)
Sludge
Dust
Zn
.41
.37
.16
.17
Pb
.04
.04
.01
.01
Sn
.06
.04
.04
.04
Al
3.61
3.55
5.05
5.05
K
7.49
8.74
1.87
2.87
Mg
1.93
1.70
.28
.25
Ca
6.95
6.38
1.91
1.68
Mn
6.86
5.75
19.36
21.22
Na
.51
.48
.07
.05
C
7.4
7.6
9.5
7.1
Moist-
ure
26.4
27.4
-
-
Total
Fe
2.4
1.4
4.8
5.3
Si02
5.42
5.41
6.17
6.8
Table 3.4-2 PARTICLE SIZE ANALYSES OF BF FERROMANGANESE DUST AND SLUDGE
(Cumulative Percent Retained on Screen)
Sludge
Screen Sizing
Sludge 44 micron
20 micron
10 micron
Sample 1
3.5%
11.1
24.3
Sample 2
4.6%
11.3
24.6
Dust
Screen Sizing
Dust 8 mesh
16 mesh
30 mesh
50 mesh
100 mesh
200 mesh
325 mesh
Sample 1
0.1%
.2
4.7
28.0
62.1
84.1
92.4
Sample 2
_
.1%
3.2
22.8
63.5
89.4
94.9
-------
furnace ferromanganese production are considered, the total quantity
of this type of residue was regarded as "small." Since the residue
quantities are small and are usually recycled or sold, the
representatives of the foreign steel industry and iron and steel
works whom we visited were not aware of any problem in the disposal
of these residues.
However, after our visit to the BSC in England, the following
(3)
information was obtained : The BSC ferromanganese blast furnace
production, centered on Teesside in the northeast of England, was
191,000 tons/year in 1974-75.
"...6,200 tons of primary dust were collected dry, but the
pyrophoric nature of this material means it is very difficult
to handle and, therefore, is wetted to form a slurry. This
slurry is combined from solids arising from secondary cleaning
to yield approximately 19,000 tons of solids containing 40%
moisture and approximately 25% of manganese dry weight. These
solids contain unacceptable amounts of cyanide and alkali.
Current practice is to dump."
65
-------
3.4 REFERENCES - BLAST FURNACE (FERROMANGANESE)
1) Development Document for Proposed Effluent Limitations Guidelines
and New Source Performance Standards for the Steelmaking Segment
of the Iron and Steel Manufacturing Point Source Category.
EPA 440/1-73/024. U.S. EPA, 1974.
2) Annual Statistical Report for 1974. American Iron and Steel
Institute, Washington, D.C. , 1975.
3) Private communication from John M. Campbell of the British Steel
Corporation.
66
-------
3.5 SUBCATEGORY: BASIC OXYGEN FURNACE (EOF)
The continuing phase-out of the open hearth furnaces (OH) is the result
of the development in the early 1950's of the basic oxygen process
(EOF) . The latter is faster, requires no supplementary fuel addition,
and is specifically designed for the efficient utilization of oxygen.
Its one drawback is an inability to process as much scrap as the OH
furnaces since process heat availability limits it to 30% or less
scrap in the charge.
The basic oxygen furnace is a cylindrical or barrel-shaped refractory-
lined vessel with a closed bottom and a reduced diameter but nonetheless
open top through which the charge and oxygen are added. The vessel is
mounted on trunions and is tillable so that molten steel can he poured
(tapped) out of an upper side tasp hole when rotated in one direction
and slag can be discharged with full inversion of the vessel with
counter rotation.*
Scrap and hot metal constitute the charge which is added to the slightly
tilted vessel. The scrap is charged first, followed by the molten iron.
The vessel is then raised to a vertical position, the lance inserted and
the oxygen blow is begun. Following this, the flux additions (lime and
fluorspar) are made through an overhead chute projecting through a
water-cooled hood surrounding the lance and open end of the vessel. The
hood, in turn, is connected to an exhaust fan. Tap-to-tap time is in
the order of one hour or less.
* United States Steel Corporation has developed a modified version of
this process using a bottom blown vessel which they call the Q-BOP
process. This became practical with a breakthrough in bottom design
allowing the blowing of oxygen without excessive bottom erosion. This
approach is said to yield slightly more steel (less loss) and lower
nitrogen, carbon and sulfur levels in the finished steel than the normal
BOP. One of the eight plants we visited using basic oxygen furnaces had
Q-BOP operations.
67
-------
Basic oxygen furnaces are built in a wide variety of sizes ranging from
roughly 50 tons to 350 tons per heat. As is the case with blast
furnaces, the newer BOF's are usually of the larger capacities. In 1974
81,522,000 tons of carbon and alloy steels were produced in these
( 21)
furnacesv ' . This represents about 56% of the total U.S. steel
production for the year.
Our study took us to eight plants having a total of 20 BOP vessels.
They ranged in size from 130 to 335 tons/heat. Two of these units were
Q-BOP types rated at 200 tons/heat.
Oxygen blowing inherent to the process generates substantial quantities
of verj fine particles that are carried out of the vessel in the off-gas.
Wet, semi-wet and dry systems are used for removing the particulate
matter from the gas stream.
(2)
A recent EPA Development Document covered the BOF operations in two
subcategories (wet and semi-wet). But for our purposes, a single
subcategory was more preferred because the residues generated in wet or
semi-wet BOF pollution control facilities are similar in compositions
and quantities.
The wet systems normally utilize venturi scrubber(s) in conjunction with
prior gas conditioning in a "wet spark box" or "quencher." A dry
electrostatic precipitator is substituted for the scrubber in the semi-
wet approach (after "wet" gas conditioning). Dry electrostatic
precipitators are also used for the final cleaning of the off-gases in
the dry system, rather than baghouses. Six of the eight installations
we visited used the wet system, one a semi-wet and the remaining plant,
a dry system. The Q-BOP shop (wet) had a dust leg to remove the
coarser particles ahead of their quencher and scrubber.
The wet gas cleaning circuit yields two residues: a coarse product
("sands") and a fine product ("fines"). Settling basins or tanks,
68
-------
usually fitted with rakes, are used to remove the former, and classifiers
and thickeners followed by filtering for the latter. Flocculation
polymers are generally added to facilitate the settling of the fines.
The semi-wet circuit, of course, yields a wet coarse fraction and dry
fines (dust). In the dry systems, both the coarse and fine fractions
are dry. In all cases, both the coarse and fine residues were, in effect
if not in practice, considered as one type from a disposal or reuse
standpoint.
Many shops have an additional dry collection system to handle emissions
during charging and tapping; four of the eight we visited did. These
are invariably baghouse operations that collect a rather small amount of
(3)
dust over a period of a year. Brinn reports that these emissions
are in the order of 0.07 kg/ton of metal poured. Our findings
(approximate) were: .13, .19, .01 and .15 kg/ton for the respective
plants.
The results of the chemical analyses of the dust and sludge samples
collected or obtained for this study are given in Table 3.5-1 (fines)
and 3.5-2 (sands). As can be seen from these results, the chemical
compositions of the BOF residues vary considerably. The iron content
in most cases is between 50 and 60%; however, values as low as 32.4%
and as high as 66.4% were encountered in our samples. The variation in
zinc is even greater, from 0.01% to as high as 13-14%.
The variation in chemical composition of residues is attributed to the
variation in the raw materials used in BOF steelmaking, e.g., the more
zinc or lead containing scrap used, the higher the zinc and lead content
of the residues will be. This is due to the fact that during steelmaking
the zinc and lead, having low boiling points, easily volatilize, and
after oxidation in the air, or oxygen mixture, are recovered as dusts
during the BOF off-gas cleaning operations.
69
-------
Table 3.5-1 CHEMICAL ANALYSES 0? EOF RESIDUES
(weight % - dry)
FINES
Plant
, a
Sample
Sludj~eb
1
2
F bust °
1
2'
G Sludgeb
1
1 -
3
i 4
I
Sludge
1
2
Fe
45.2
43.9
58.3
60. 4
60.2
60.7
61.9
61.8
55.6
56.5
3 57.4
* 55.6
K
C
2.9
3.1
' 0.7
0.5
1.4
1.5
1.3
1.2
1.7
1.4
1.3
1.6
Slv.decbi
; : 53.4 | 1.5
2 =51, 2 1.5
j
3 '57.5
4 ! 56.2
1.1
2.6
S I Pb
0.18
0,44
0.04
0.01
0.20
0.17
0.15
0.13
0.14
0.13
0.13
0.11
0.13
0.09
0.05
0.04
1.8
1.7
1.6
1.4
0.04
0.07
0.06
0.05
i
0.10
0.10
0.07
0.15
0.73
0.60
0.29
0.60
Sn
•0.02
0.04
0.02
0.03
0.06
0.04
0.04
<0.01
<0.01
<0.01
<0.01
C0.01
0.05
0.02
0.01
0.02
Zn
12.8
13.7
0.24
0.12
2.0
1.7
1.6
1.4
0.07
0.07
0.09
0.07
4.5
3.5
1.4
3.7
Mn
.
0.58
Na?0
0.07
0.55 0.05
0.12
0.13
0.50
0..27
0.35
0.11
0.52 0.07
0.41
0.37
0.36
0.50
0.59
0.34
0.12
0.08
0.14
0.35
0.07
0.07
0.11'
0.09
0.11
0.09
0.16
0.13
0.11
0.13
V
0.27
0.23
1.2
0.70
0.31
0.29
0.22
0.27
0.12
0.12
0.12
0.12
0.35
Al?0,
0.30
0.25
0.09
0.08
0.08
0.09
0.11
0.08
0.11
0.08
0.08
0.09
0.17
0.4V 0.55
0.27
0.37
0.17
0.25
CaO
5.6-
5.9
7.6
6.0
3.6
4.2
3.4
3.6
6.9
6.1
5.7
6.5
&.0
8.9
6.4
4.6
MgO
0.66
0.60
0.61
0.61
0.98
0.99
0.80
0.75
2.0
2.4
2.0
2.6
1.1
1.2
1.4
1.0
SiO?
1.8
2.8
1.6
2.3
2.0
As
^0.02
<0.02
<0.02
<0.02
<0.02
Sb
<0.01_.
<0.01
<£0.01
<0.01
<0.01
Se
£0.01
.
<0.01
<0.01
-------
Table 3.5-2 CHEMICAL ANALYSES OF BOP RESIDUES
(weight % - dry)
- SANDS
Plant
b
A
EC
I
J
Sample
Filter
cake'
1
2
Sludgeb
1
2
Sludged
1
2
3
4
d
Sludge
1
2
3
4
Fe
59.1
50.6
35.0
32.4
52.9
46.1
47.3
55.5
53.7
66.4
61.6
59.3
C
0.9
1.8
1.0
2.0
1.6'
1.1
1.0
0.9
0.6
0.4
0.7
0.5
S
0.02
0.04
0.06
0.08
0.10
0.09
C.06
0.02
•C0.01
<0.01
0.01
0.01
Pb
,
0.02
0.21
0.01
0.02
<0.01
0.01
<0.01
•iO.Ol
•C0.01
<0.01
0.01
0.01
Sn
0.10
0.10
0.02
0.04
0.02
0.02
0.01
0.01
<0.01
0.01
<0.01
0.01
Zn
0.01
0.01
0.3
3.3
0.01
0.01
0.01
0.01
0.03
0.05
u.05
o.oa
Mn
0.61
0.52
0.67
0.72
0.32
0.28
0.36
0.88
0.16
0.25
0.47
0.33
Na2°
0.03
0.11
0.03
0.03
0.04
0.03
0.03
0.01
0.01
<0.01
0.01
0.01
K20
0.03
0.18
0.14
0.16
0.08
0.07
0.05
0.05
.
0.01
0.01
0.01
0.01
A1203
0.13
0.38
0.62
0.53
0.25
0.21
0.25
0.25
0.15
0.08
0.13
0.15
CaO
15.9
11.4
23.7
20.8
16.1
15.2
15.4
13.8
5.4
2.8
5.4
9.2
MgO
2.0
1.8
2.1
1.6
8.3
4.8
5.7
3.6
1.7
0.79
1.8
2.1
Si02
3.4
13.0
2.8
3.7
As
<0.02
<0.02
<0.02
4.0.02
Sb
<0.01
-------
-3
CO
Table 3.5-3 CHEMICAL ANALYSES OF EOF RESIDUES (FROM LITERATURE)
(% dry basis)
Raf .
3d
(R) 4
5* •
6a
(R) 7C
8C
9C _J
(A) 10°
10C
(A) 1QC
lld
lld
(R) 12d
13d '
13C
I4d
15d
16C
(R) 17C
Fa
52.2
52.0/
56.1
60
56.5
50. 5/
79.2
64.8
57.1
55.7
55.7
54.0
59.0
75.0
4I.'3/
53.0
62.0
54.5
64.1
56.0
55.7
47. 0/
83.6
C
1.0
Trace/
1.3
_
1.45
Trace/
0.55
-
0.56
0
0.44
_
0.2
0,2
0.8/
6.1
0.1
0.2
-
-
0.44
0.2/
1.0
S
-
O.I/
2.0
0.7
0.06
0.03/
1.4
0.03
-
0.2
0.11
_
0.6
0.5
O.I/
0.2'
0.3
0.2
0.5
0.1
0.11
—
Pb
-
Trace/
0.29
0.3
0.09
. C.21/
0.79
-
o.ooi
0.3
0.44
0.4
-
_
- ...
0.3
0.2
-
-
0.4
0.19/
0.75
sJ
-
Trace./
0.46
—
-
-
-
-
_ ,
-
_
-
_
r -
—
-
-
-
—
Zn
-
Trace/
3.6
3.0
2.0
2.37/
15.1
1.1
5.1
1.5
6.3
3.0
-
-
0,3/
7.1
2:8
0.4/
2.0
0.4
0.5
6.3
0.16/
2.5
Mn
0.93
0.31/
1.3
_
1.0
0.25/
0.9.5
-
0.90
_
-
1.0
2.0
2.0
-
•"
-
-
0..54
!
NagO
-
_
-
-
-
-
_
-
-
_
-- -
-
•~
-
-
0.34
0.47
K2°
0.1
_
-
-
-
-
_
-
-
_
-
0.3
0.6
-
-
-
0.15
A12°3
0.8
Trace/
3.6
0.04
0.25
Trace/
0.2
0.1
0.10
_
-
-
_ '
0.6/
1.8
-
~-
-
0.4
3.0
—
CaO
11.1
0.3/
7.9
5.0
4.0
C.75/
5.2
1.8
2.9
6.0
-
2.0
2.0
12. 2/
15.9
1.4
12.5
1,5
12.5
5.3
•*
MgO-
1.8 '
0.15A
2.6
„
1.6
O.ll/
0.37
0.1
0.56
0.3
-
-
_
1.8/
8.6
0.7
0.5
-
1.3
0.50
™
Si02
2.2
0.34/
1.8
_
1.7
0.65/
1.2
-1 -V
J-. /
1.7
1,7
-
1.0
.1.0.
1.9/
2.5
0.9
1.4
1.1
2.4
4.7
™
a Raw fume b Slurry c Dust
d Fines (A) Average
(R) Range of composition
reported in reference
-------
-a
CO
Table 3.5-4 PARTICLE" SIZE ANALYSES OF EOF RESIDUES
(Cumulative Percent Retained on Screen)
'
Screen
6 mesh
16 mesh
30 mesh
50 mesh
100 mesh
200 mesh
325 mesh
325 mesha
20 micron
10 micron
Fines (Sludge or Dust) at Plant
E
4.6%
14.1
19.0
F
26.7%
34.6
39.5
G
20.5%
50.0
66.5
T
11.4%
18.6
22.9
K
19.9%
29. S
34.4
L
'7.9%
11.6
16.0
M
3.2%
7.9
10.9
Sands at Plant
A
-
-
1.9%
9.4
33.0
70.9
86.9
83.3
90.3
90.8
E
-
0.1%
6.5
32.2
62.3
83.9
92.4
92.2
-
- ,
I
-
-
0.1%
10.3
33.9
66.8
82.0
74.1
82.2
84.5
J
-
1.1%
5.4
21.0s
67.1
93.5
96.4
96.6
98.1
98.7
a Separate screening of another portion of sample.
-------
Representative data from the literature are presented in Table 3.5-3
and show the same types of variations in the analytical results as
those observed in our study.
From the sizing standpoint, BOF dusts are extremely fine with the bulk
of material reported to be 1 micron or less ' ' . Our particle
size analyses are given in Table 3.5-4.
The very fine particle size of some of the residues (i.e., the fine dusts
and sludges) and the difficulty of dewatering the sludges present some
problems in the management and disposal of these wastes. Before reuse
or even disposal, the dewatering and/or agglomeration of these residues
is often the practice.
BOF operations produce substantial dust emissions, with reported values
in the U.S. plants varying from 8 kg/ton of product to 30 kg/ton.
The eight plants we visited collected an average of roughly 20 kg of
dust and sludge (dry basis) per ton of steel product (Table 3.5-5).
In these works, almost 90% of the collected residue is in sludge form
with the balance in dust.
Table 3.5-5 BOF SLUDGE AND DUST COLLECTIONS - 1974
Plant
A
D
E
F
G
I
J
K
Weighted Avg.
Residue Collected - % Steel Prod.
Sludge3
2.0
0.6
0.5
-
3.0
2.0
1.8
1.5
1.79
Dust
-
1.4
0.2
2.5
-
-
-
-
0.22
Total
2.0
2.0
0.8
2.5
3.0
2.0
1.8
1.5
2.0
a Dry basis
74
-------
The method of EOF residue disposal for the eight steel works with EOF
operations is presented in Table 3.5-6. Of the residues, 24.3% is
recycled via the sinter strand, 50.2% is landfilled, and 25.5% is
stocked.
Table 3.5-6 EOF RESIDUE DISPOSITION - 1974
Plant
A
D
E
F
G
I
J
K
Disposit ion
Landfill
Landfill
Recycle - sinter
50% recycled/ sale - 50% stock
Landfill
Stocked
Recycle - sinter
Stocked
Summation: Weighted Average
Landfill 50.2%
Recycle 24.3%
Stock 25.5%
The main problem in recycling of the EOF pollution abatement residues
is the tramp element content (mainly zinc and lead) and to a lesser
extent, the fine consistency of the EOF pollution control residues.
(For details on problems of recycling, see Section 3.16, Recycling.)
Based on information obtained in England, Germany and Japan and from
data in the literature(2'4'5'10'11'14'17 the chemical composition and
size distribution^ of the fines in other countries are essentially
the same as in the U.S. The quantities of residues collected from the
EOF operations are also very similar (Table 3.5-7).
75
-------
Table 3.5-7 QUANTITIES OF EOF POLLUTION
CONTROL RESIDUES COLLECTED
BY COUNTRIES
(kg/ton of steel)
United States
England
Germany
Japan
8 - 30
14 - 20
13 - 30
11 - 25
The quantities in the U.S. vary between 8 and 30 kg/ton of steel
produced, while in the other three countries, with high steel production,
the quantities are between 11 and 30 kg/ton.
For the collection of the residues abroad, "wet" pollution control
devices are usually used. Even in Germany and Japan where earlier
"dry" systems were used to a significant extent, the trend today is
toward scrubbing (mostly in venturi-type scrubbers) and toward wet
electrostatic precipitators. However, even in some of their
most modern facilities, dry electrostatic precipitators are still
used by the Japanese. Baghouses are also used in Japan to control
the EOF "fugitive emissions."
In Japan the recovery of BTU values from the EOF off-gases, especially
since the energy crises, is becoming popular. For instance, in one
steel works, the ICR (IRSID, France), systems are used but .their newest
furnace utilizes the Bischoff (German) gas recovery system.
(19)
An international study gives somewhat higher figures (30-33 kg/ton)
for particulates generated in EOF operations (Table 3.10-8).
76
-------
Table 3.5-8 RAW RESIDUAL LOADS ASSOCIATED WITH BOF
STEEL MANUFACTURING PROCESSES^19)
Type of Discharge
Raw Residual Load
(kg/ton of Steel)
BOF - Airborne
Participates
BOF (Semi-wet) Waterbome
Suspended solids
Fluoride
PH
BOF (Wet) Waterborne
Suspended solids
Fluoride
pH
30.0 - 33.0
0.5
0.04
10 - 12
5.0
0.08
6-9
Presently About 41% of the BOF residues are recycled in England while the
goal is toward 100% recycling in Germany and Japan. The Germans have
developed the Berzelius-Lurgi variations of the Waelz process and the
SL/RN process, and the Japanese, the Kawasaki process. The Japanese,
using partly the German-American SL/RN and the Kawasaki processes,
are already recycling even the zinc and lead-containing residues,
and in Germany the Berzelius-Lurgi plant has been in operation since
1974. The BSC has completed a feasibility study and has considered
building a recycling unit capable of handling Zn and Pb-containing BOF
and other residues
(17)
77,
-------
3.5 REFERENCES - BASIC OXYGEN FURNACE
1) The Making, Shaping and Treating of Steel - Ninth Edition,
United States Steel Corporation, 1971.
2) Development Document for Proposed Effluent Limitations Guidelines
and New Source Performance Standards for the Steelmaking Section
of the Iron and Steel Manufacturing Point Source Category,
EPA 440/1-73/024, U.S. Environmental Protection Agency, Feb. 1974.
3) Brinn, D. G. A Survey of the Published Literature Dealing with
Steel Industry In-Plant Fines and Recycling. NTIS, PB-236,359,
1974.
4) Hopkins, D. W., Johnson, W., and Davies, R. Constitution of Oxide
Fume from Steelmaking. Ironmaking & Steelmaking Quarterly, No. 1,
(British Steel Corporation), 1974, pp. 25-29.
5) Anonymous. Recycling of Steel Plant Waste Materials. Steel
Research - 1974, British Steel Corporation, 1975.
6) Holley, C. A., and Weidner, T. H. New Process for Converting
Steelmaking Fumes into Low-Zinc Pellets. AISI Regional Meeting,
Chicago, 1969, pp. 1-8.
7) Holowaty, M. 0. A Process for Recycling of Zinc-Bearing Steel-
making Dusts. AISI Regional Technical Meeting, Chicago, 1971,
pp. 149-171.
8) Saito, Yoshio. Direct Reduction Process for Recycling Steel Plant
Waste Fines. In: AIME Ironmaking Proceed, Vol. 30, 1971, pp. 126-145,
9) Goksel, M. A. Recovery of Iron, Zinc and Lead from BOF Dust and
Other Steel Plant By-Products." In: TSM-AIME Ironmaking
Proceedings, 1971, Vol. 30, pp. 126-145.
10) Serbent, H., Maczek, H., and Rellermeyer, H. Large Scale Test for
the Treatment of BF Sludge and BOF Dust According to the Waelz
Process. AIME 34th Ironmaking Conference, April 15, 1975, Toronto.
11) Cavaghan, N. J., and Traice, F. B. Utilization of In-Plant Fines.
JISI, 1970, 208 (6), pp. 538-542.
78
-------
3.5 REFERENCES (continued)
12) George, H. D., and Boardman, E. B. The IMS-Grangcold Process
for Agglomerating Steel Mill Waste Material. Granges Ore News,
October 197S3, pp. 13-21.
13) Wetzel, R., and Meyer, G. Processing of Steel Works Dust and
Slurry. ISI Publ. 139,Operation of Large BOF's, 1971, pp. 44-51.
14) Tanaka, M., et al. The Properties of Reduced Pellets made from
Basic Oxygen Furnace Dust. Translation HB7 402 (ex. Tetsu-to-
i
Hagane), 1967 (11), pp. 1166-68.
15) Pugh, J. L., and Fletcher, L. N. Experience in Handling and
Consuming Basic Oxygen Flue Dust in a Sinter Plant. In:
Proceedings of TMS-AIME Ironmaking Conference, Chicago, 1972,
pp. 5.
16) Dressel, W. M., et al. Removal of Lead and Zinc and the Production
of Pre-Reduced Pellets from Iron and Steelmaking Wastes.
U.S. Bureau of Mines,NTIS Report PB-234 688/OWP, July 1974 (20),
Special Report.
17) British Steel Corporation. The Arising and Treatment of BSC
In-Plant Fines. Swinden Laboratories, Moorgate, Rotherham, 1975.
18) Parker, C. M. Basic Oxygen Air Cleaning Experiences. Journal
of Air Pollution Control Association, 16 (8), 1966.
19) Organization for Economic Cooperation and Development, Environment
Directorate, PCC/AETJ/ENV/75.2 (Preliminary Draft), August 1975.
20) Barnard, P. G., et al. Recycling of Steelmaking Dusts. In:
Proceedings of 34rd Mineral Waste Utilization Symposium, Chicago,
1972, pp. 63-68.
21) Annual Statistical Report for 1974. American Iron and Steel
Institute, Washington, D. C., 1975.
79
-------
3.6 SUBCATEGORY: OPEN HEARTH FURNACE (OH)
The conversion of molten iron to steel is accomplished in one of three
furnace types: open hearth (OH), basic oxygen (EOF), or electric (EAF),
At one time most of the steel produced in this country was made in
open hearth shops but their popularity has been falling rapidly since
the introduction of EOF steel making' . Table 3.6-1 shows the extent
(2)
of the decline of the importance of OH in the production of steel
Table 3.6-1 PERCENT OF RAW STEEL PRODUCED BY FURNACE TYPE
Furnace Type
Open hearth
Basic oxygen
Electric
Other
Total %
Raw steel produced in
100,000 tons
Percent of U.S. Production
1974 1969 1964
24.3
56.0
19.7
-
100.0
145.7
43.1
42.6
14.3
-
100.0
141.3
77.3
12.2
9.9
0.6
100.0
127.1
There have been no new OH facilities built in this country in recent
years and based on information obtained from the steel companies there
are no plans to construct new ones in the future, since both the EOF
and EAF offer savings in time and energy costs. As a result, the open
hearth method of producing steel will continue to decline in importance
as the older furnaces are taken out of service.
The open hearth furnace is a shallow, rectangular, covered hearth. A
charge is evenly distributed on the refractory hearth and heated by passing
hot burning gases over the materials from alternate ends of the furnace.
In a normal regenerative operation checker chambers are used for heat
recuperation. Oxygen is usually added through roof lances to increase
80
-------
flame temperatures and heat transfer after the hot metal was added
to the hearth. This is done to reduce a normal charge-to-tap time
of 10 hours to 7-8 hours^ .
Firing time is largely dependent on the size and makeup of the charge
which, in theory but not in normal practice, can vary from all hot metal
to all scrap. The charge composition depends upon the relative avail-
abilities of hot metal and in-plant or purchased scrap, with typical
i
scrap usage in the 45 - 55% range. The solid components are charged
first. These will normally be scrap and/or cold pig iron, fluxing agents
(limestone or lime primarily) and raw ore, briquettes, sinter or nodules
as a source of reaction oxygen. At the proper time and with partial
melting of the solids, the molten iron is introduced. Then, after
several distinct reaction phases within the bed and a final refining
period, during which most of the C and S are removed from the melt,
the charge is ready to tap.
In 1970 there were 408 basic open hearth furnaces in the United States
in operation, with capacities ranging from 30 to 600 tons/heat(D.
This included a small number of tilt-type furnaces that were or had been
previously used in duplexing operations. Also 10 acid open hearths
still in operation were reported(!'. Open hearth steel production in
1970 was 48,022,000 tons whereas in 1974 only 35,499,000 tons of OH
steel were produced^), confirming the continuing decline in the usage
and availability of these units.
The four plants we visited with OH shop operations had a total of 25
OH furnaces in 1974 with capacities ranging from 240 tons/heat to 335
tons. Operating fuels for these units varied from oil and tar to
natural and by-product gases.
Cleaning of the off gases from furnace operations is the major and only
source of pollution abatement residues in typical OH steelmaking practice.
Because of the nature of the charge and the variety of firing fuels,
81
-------
these gases usually contain not only entrapped particulates but also
combustion as well as reaction products. Wet and dry gas cleaning
systems are used. If wet, venturi scrubbers are standard; if dry,
dry electrostatic precipitators are used.
Since the four shops we visited all had dry cleaning systems and a dust
residue, we were not able to obtain first-hand information relative to
(3)
wet collection systems. However, it is reported that the aqueous
discharge from wet scrubbers is treated the same as in EOF practice
except that pH adjustment has to be made because of the acidic nature
of the discharged wastes. This same source describes two such systems,
both of which use water recycle and blowdown. Coagulation aids are
needed to settle the solids because of the fineness of the
suspended particles.
Our chemical analysis of the dust samples obtained for this study are
given in Table 3.6-2. The iron content of the dusts varies from 34.4 -
65.7%. The tramp element content such as zinc varied from less then 0.05
to as high as 26.6%, lead from 0.07 to 2.0%,and the Na£0 + K 0 content
from 0.67 to 3.15%. Similar variation in the chemical composition of
the OH residues is shown in the data presented in the literature (Table
3.6-3).
The results of our sample screenings, particle size analysis, are
presented in Table 3.6-4, indicating that all open hearth dusts are of
very fine consistency. According to one source in the literature(6)
50% of the OH fines are below 5 microns in the U.S. A paper on Czech OH
practices indicates that 7Q% of the dust particles are below 1 micron
Of the three major steelmaking processes (OH, BOF, and EAF), the open
hearth process produces the smallest amount of pollution control residue
on a kg-per-ton-of-raw-steel-produced-basis. The four operations we
observed had a weighed average of collected dust equivalent to 1.1%
(11 kg/ton) of steel produced (Table 3.6-5). Similar quantities of
82
-------
OH dusts generated (e.g., 10 kg/ton^11) or 4.2 kg/ton without oxygen
lancing and 4.7-11 kg with oxygen lancing(19)) were reported in the
literature. However, it should be noted that the quantities generated
depend not only on the processing practices but also on the composition
of the raw material feed. For instance, if a high ratio of scrap with
high zinc and lead content is used, quantities of dusts collected also
increase (since essentially all of these volatile metals are expelled
during the steelmaking).
None of the four plants indicated that they were directly recycling any
of their dusts at the time of our visit. One plant was selling its
waste to an associated outside concern for non-steel use. Another was
stockpiling in anticipation of the startup of a briquetting facility
which would handle this as well as other fine plant wastes. Presumably
these briquettes would then be recycled within the plant as furnace
feed. The remaining two installations sent their dust to landfill sites.
Overall, we found that 58% of the dust was landfilled, 29% stocked, and
13% sold. Obviously, this small sampling has distorted the true industry-
wide picture since the sale of these residues is minimal according to
most authorities on the subject.
In Germany in 1974 there were no pollution controls on open hearth
furnaces and, therefore, no residues were collected. As late as 1975,
during our visit to Germany, only one experimental open hearth off-gas
dedusting system was in operation, but the residue quantities collected
with this experimental electrostatic precipitator were not available.
According to the OECD, ED study 2-20 kg airborne and 5 kg waterborne
residues are generated in open hearth operations(1^' (Table 3.6-6).
In Japan only 1.3% of the raw steel produced during 1974 was made in
open hearth furnaces(12). Since it is regarded as a negligable problem
by the Japanese steel industry and the Environment Agency of Japan, the
only information obtained on this subject was the typical chemical
analysis of OH residues (see Table 3.6-3, reference 15) from the
83
-------
Environment Agency.
In England "only certain" OH furnaces have dust control equipment on
the off-gases. The quantities of residues collected are relatively
small (i.e., less than 5% of all of the dust collected in the iron and
steelmaking furnace operations). In the British Steel Corporation
facilities, 26,000 tons of OH residues are collected of which none
are recycled. Of this 26,000 tons, 4,000 (or 15%) are sold and 22,000
(13)
(or 85%) are dumpedv.
In the U.S., based on the information obtained from the four plants
which had OH operations, as stated before, 87% of the OH residues are
dumped or stocked and 13% sold. Based on additional information obtained
during our study, less than 20% of the OH residues were sold or recycled
in the U.S. in 1974.
The main problems in the recycling of these residues are (1) the high
tramp element content, especially zinc and lead, and (2) the very fine
consistency of the dusts.
For further details on problems of recycling OH residues, see Section
3.16, Recycling.
84
-------
Table 3.6-2 CHEMICAL ANALYSES OF OPEN HEARTH DUSTS
(weight %) .
Plant
C
F
G
-
H
Sample
1'
2
3
4
1
2
1
2
.3
4
1
2
3
4
1
Fe
62.0
58.3
58.8
55.5
64.3
65.2
49. 7
34.4
48.6
46.3
64.7
C
0.3
0.3
0.5
0.3
0.5
0.4
0.4
0.3
0.3
0.4
1.2
64.2 1 0.5
64.7 I 0.4
65.7 ' 0.7
1
S
1.1
1.2
1.0
1.3
1.2
0.78
1.3
0.93
0.99
0.20
0.46
0.11
0.61
0.51
Pb
0.6
1.4
1.2
1-6
0.14
0.07
2.0
1.3
1.9
1.5
0.46
0.83
0.52
0.35
Sn
0.09
0.10
0.06
0.10
<0.01
<0.01
0.12
0.10
0.13
0.10
0.02
0.02
0.03
0.02
Zn
2.0
3.5
4.8
5.8
0.23
0.18
10.5
26.6
12.0
16.6
0.07
0.07
0.33
0.03
Mn
0.18
0.20
0.16
0.12
0.07
0.06
0.11
0.02
0.19
0.07
0.38
0.16
0.17
0.12
Na20
0.23
0.43
0.36
0.50
0.35
0.27
0.44
0.47
0.85
0.43
0.16
0.15
0.20
0.13
K?0
1.8
2.1
2.3
2.1
0.73
0,54
2.5
2.1
2.3
2.1
0.71
0.52
0.59
0.83
A1203
0.15
0.13
0.11
0.13
0.15
0.11
0.19
0.17
0.26
' 0.19
0.45
0.17
0.11
0.04
CaO
1.2
O.E3
0.'95
0.87
0.74
O.S2
0.93
0.48
0.97
0.46
2.6
1.2
0.82
0.50
MgO
0.32
0.27
0.37
0.27
0.28
0.27
0.48
0.22
0.70
0.23
0.90
0.41
•0.40
0.20
Si°2
0.7
0.5
0.5
0.8
As
<0.02
<0.02
<0.03
46,02
Sb
<0.01
40-01
40.01
40.01
Se
40.01
410.01
4:0.01
40.01
oo
Oil
NOTE: All samples are from dry ESP.
-------
Table 3.6-3 CHEMICAL ANALYSES OF OPEN HEARTH RESIDUES (from Literature)
(weight % dry basis)
Reference
5
. 6
7
'i 8 a
;
:9a
13
15
15
Fe
66.0
55.0
50.5
63. 5/
68.0
55.9/
63.7
27^51
65.1
64.7
C
0.64
"~
- -
-
_
-
-
-
S
.0.55
1.1
0.34/
0.70
0.40/
2.7
-
0.2
. O-.l •
Pb | Zn
0.12
0.8
0.8
0.05/
0.95
0.50
1.8-2,5
-
-
3.0
5.0
15.1 .
0.21/
1.64
0.58/
1.7
8-10
1.2
• 1.4 .-
Mn
0.35
0.3
0.2
_
0.47/
0.49
-
--
. • ' '!
Alkalies
-
_
-
_
0.47/
6.49
2
-
» . .
A1203
0.25
_
0.2
-
0.47
0.67
-
-
••. .- ..
CaO
0.94
-
0.7
-
0.85/
1.06
-
0.6
...1.6,.
MgO
0.4 ;
;
0.3 ',
-
0,39/
i.sa
-
-
M
SiOo
1.1
_
0.6 •'
-
0.4/
0.92
-
0.7
0.3,.
00
Oi,
a- Range of results reported by the authors.
-------
Table 3.6-5 PARTICLE SIZE ANALYSES OF OPEN
HEARTH DUSTS
(Cumulative Percent Retained on Screen)
Screen
30 mesh
50 mesh
100
200 mesh
325 mesh
325 mesh a
20 micron
10 micron
C
T
0.1%
1.0
8.3
22.8
21.2
42.7
57.9
Plan
F
_
-
-
-
-
8.4%
18.5
24.9
t
G
_
-
-
-
-
5.0%
12.4
15.2
H
_
-
-
-
-
3.6%
8.6
12.6
a Separate screening of another portion of sample.
Table 3.6-5 QUANTITIES OF RESIDUES GENERATED
IN OPEN HEARTH STEELMAKING OPERATIONS
Plant
C
F
G
H
Weighted Avg.
Residues Collected
% of Raw Steel
1.0
0.6
1.2
2.0
1.1
87
-------
Table 3.6-6 RAW RESIDUAL LOADS ASSOCIATED WITH
THE OPEN HEARTH STEEL MANUFACTURING
Type of Discharge
OHF - Airborne
Particulates
so2
OHF (Wet) - Waterborne
Suspended solids
Fluoride
Nitrate
Zinc
(pH)
Raw Residual Load
(kg/ton of steel)
2.0 - 20.0
0.7 - 6.0
5.0
0.05
0.09
1.0
(3 - 7)
88
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3.6 REFERENCES - OPEN HEARTH FURNACES
1) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
2) Annual Statistical Report for 1974. American Iron and Steel
Institute, Washington, D. C., 1975.
3) Development Document for Proposed Effluent Limitations Guidelines
and New Source Performance Standards for Steelmaking Segment
of the Iron and Steel Manufacturing Point Category.
U.S. Environmental Protection Agency, EPA 440/1-73/024, 1974.
4) Lund, H. F. Industrial Pollution Control Handbook.
McGraw-Hill Book Company, New York, 1971.
5) Holley, C. A., and Weidner, T. H. New Process for Converting
Steelmaking Fumes into Low-Zinc Pellets. AISI Regional Meeting,
Chicago, 1969, pp. 1-8.
6) Barnard, P. G., et al. Recycling of Steelmaking Dusts. In:
Proceedings of 3rd -Mineral Waste Utilization Symposium, Chicago,
1972, pp. 63-68.
7) Holowaty, M. 0. A Process for Recycling of Zinc-Bearing
Steelmaking Dusts. AISI Regional Technical Meeting, Chicago,
1971, pp. 149-171.
8) Thorn, G. G. W., and Schuldt, H. A. The Collection of OH Dust and
Its Reclamation Using the SL/RN Process. Canadian Mining &
Metallurgical Bulletin, October 1966, pp. 1229-1233.
9) Trace Pollutants from the Processing of Metallic Ores.
U.S. Environmental Protection Agency, EPA 650/2-74/115, October
1974.
10) Bartacek, J. Dust Removal from the Combustion Products in Oxygen
Intensified Open Hearth Furnaces. Hutnick, 1969, pp. 334-339.
11) Brim, D. G. Survey of the Published Literature Dealing with the
Steel Industry In-Plant Fines and their Recycling. U.S.
Environmental Protection Agency, NTIS, August 1974, pp. 236-358.
12) Japan's Iron and Steel Industry - 1975. Kanata Publicity, Inc.,
Tokyo, November 1975.
89
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3.6 REFERENCES (continued)
13) British Steel Corporation. The Arising and Treatment of BSC
In-Plant Fines. Swinden Laboratories, Moorgate, Rotherham, 1975,
14) Organization for Economic Cooperation and Development.
Environment Directorate, PCC/AETJ/ENV/75.2, Preliminary Draft,
Paris, 1975.
90
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3.7 SUBCATEGORY: ELECTRIC ARC FURNACE (EAF)
As the phasing out of the basic open hearth process has progressed in
recent years, the use of the electric arc furnace has increased. This
type of furnace, once considered primarily for alloy steel production,
accounted for almost 20% of the U.S. steel output in 1974 with over
65% of this in carbon steel grades . Part of its increasing
popularity is due to the fact that it can be used to produce the full
range of steels starting with a cold charge of scrap and/or pig iron.
Since it needs no hot metal, this furnace lends itself to those
smaller plants where basic iron production facilities are either
limited or lacking altogether. Because of its versatility, it is used
to supplement EOF operations in many of the larger integrated plants.
The electric arc furnace consists of a refractory-lined cylindrical
steel shell and dished bottom with a large shell diameter-to-depth ratio.
Since most modern furnaces use top charging, a refractory-lined,
removable top is standard. This top has three openings through which
retractable graphite electrodes are inserted. Heat to melt and process
the charge is produced by the electrical arcing between the electrodes
and the charge as well as the passage of the current through the
bath(2).
The furnaces are mounted on rocking mechanisms so that they can be
tilted backwards for slag removal and forwards for tapping. Doors or
covered ports in the shell provide for observation, fettling, oxygen
or other gas refining, and for fluxing and alloying material additions.
Mechanical or magnetic induction stirrers are normally used to agitate
the bath and assure better mixing and blending.
After charging of the scrap and fluxing agents, which may take more than
one charge/melt cycle, the melting and refining proceed. Slag control
is the important consideration in the EAF process, and the fact that
slags can be easily adjusted to meet a wide variety of operating
91
-------
conditions accounts for the inherent flexibility of the process.
Whether a single or double-slag approach is used, an oxidizing slag
is provided for the meltdown period followed by a reducing slag for
refining. Oxygen lancing during the oxidizing period shortens the
process time to roughly two to four hours . When bath chemistrie
reach the desired end points, the heat is tapped.
The U.S. EAF production in 1974 was 28.7 million tons and the four
plants which had EAF facilities of the eleven plants we visited produced
almost 2.4 million tons of steel during the same period in electric arc
furnaces.
Electric arc furnaces come in a wide range of sizes, from under 5 tons
per heat to over 300 tons. Four of the plants we visited had EAF
facilities; their 13 furnaces ranged in size from 20 tons/heat to 165
tons. All plants but one had blast furnaces to produce iron for the
EAF's.
Wet, semi-wet and dry collection systems are used to control fume
emissions from EAF's. The wet systems use venturi scrubbers; the
semi-wet, precipitators or baghouses in conjunction with "wet" spark
or spray chambers; the dry, primarily baghouses. Process waste water
effluents from the wet and semi-wet systems are clarified in much the
same way as they are in the EOF circuits, resulting in a sludge or
dewatered filter cake for disposal.
Three of the four plants in this study used baghouses. The fourth has
furnace evacuation systems and venturi scrubbers (they are in the
process of adding a baghouse for shop dust and fume control). The
water circuit here is a closed loop with a small bleed. Included in
the loop are thickeners, chemical addition (if needed), cooling tower
and vacuum filters. This same circuit handles waste waters from their
continuous casting and vacuum degassing units.
92
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Table 3.7-1 CHEMICAL ANALYSES OF EAF RESIDUES
(weight % dry basis)
Plant
A
G
H
K
Sample
Dusta
1
2
Dust3
t
J.
2
Dust3
1
2
3
4
Sludge5
1
2
3
4
Fe
39.1
35.0
'
33.5
31.8
30.6
25.0
32,0
23.9
21.7
37.0
40.6
33.3
C
1.6
1.6
0.5
0.6
0.9
0.7
0.5
0.6
3.1
0.5
2.5
3.6
S
0.23
0.16
0.29
0.03
0.24
0.21
0.24
0.22
0.06
0.05
0.11
0.15
1
Pb
0.14
0.14
3.4
3.9
1.8
1.6
1.7
3.4
0.42
0.18
0.07
0.34
Sn
0.09
0.09
0.07
0.07
0.05
0.03
0.08
0.07
0.08
0.03
<0.01
<0.01
Zn
0.31
0.28
15.1
15.2
4.5
6.1
5.2
6.4
1.6
1.1
0.17
1.4
Mn
2.2
1.4
1.8
1.6
3.3
1.1
1.8
2.1
1.2
0.9
1.5
1.0
Na20
0.32
0.31
0.64
0.23
0.32
0.55
0.32
0.57
•
0.05
0.05
0.06
0.09
V
2.4
2.3
2.8
3.2
1.1
1.1
1.4
1.7
0'.14
0.18
0.12
0.17
A1203
0.66
0.72
0.38
0.36
0.49
0.41
0.76
0.68
0.30
0.40
0.43
0.26
CaO
8.87
11.8
6.31
6.84
20.9
29.0
22.1
5.57
30.2
6.9
15.4
19.6
•MgO
4.6
6.9
2.8
2.8
2.3
2.0
2.3
2.2
1.6
1.0
1.5
1,2
Si02
4.5
3.0
3.5
1.9
As
0.02
0.02
0.02
0.02
Sb
£0.01
<0.01
<0.01
<0.01
Se
<0.01
<0.01
<0.01
,.
<0.01
to
CO
a Baghouse
b ' Filter cake
-------
Table 3.7-2 CHEMICAL ANALYSES OF EAF RESIDUES (FROM LITERATURE)
(weight % dry basis)
Plant
3a
33
. b
f\
(AK
f\
(R)b
(R)c
(R)d
(R)d
8°
Sample Fe
-
33.1
33.6
34.0
29.0
21. 11
34.9
21.8/
53.9
30. 0/
40.0
28.57
55.8
33.2
C
1.4
0.48
-
-
0.17
7.4
-
0.57
0.9
0.7
0.30
S
0.62
0.45
0.49
-
-
-
0.27
0.3
0.2/
1.0
0.48
Pb
0.92
0.84
1.5
2.0
0.67
2.7
Trace/
2.7
-
o.i/
5.1
2.6
Sn
0.01
0.003
-
-
-
-
Zn
4.8
1.4
7.4
16.0
0.97
5.2
Trace7
5.0
2.57
7.0
4.77
9.5
24.8
Mn
3.9
3.8
-
4.0
2.6/
6.4
0.57
3.3
4.6
3.87
3.9
3.3
Na20
-
-
-
-
0.57
4,1
-
-
0.5
K20
-
-
-
-
-
-
•-
o.i/
2.2
A1203
1.9
2.9
-
-
0.47
4.2
-
-
0.37
1.2
0.8
CaO
15.7
17.2
6.1
-
0.6/
7.4
-
10.87
18.0
1.97
10.5
1.3
MgO
7.8
5.9
_
-
0.77
8.8
-
-
0.67
4.1
0.4
Si02
0.12
0.10
4.6
-
-
-
3.0/
4.0
1.97
4.6
3.4
VO
a Raw fume b Dust
c Wastes
d Fines
(A) Average (R) Range
-------
Chemical analyses of the three dusts and one joint treatment sludge
from these four plants are given in Table 3.7-1. The iron values in
the EAF residues we obtained and analyzed range between 21.7 and 40.6%
(total Fe). The tramp element content, such as zinc, varied between
0.17 to 15.2%, the lead content between 0.07-3.9%, and the Na 0 + K 0
content between 0.19 and 3.4%. The high tramp element contents, in
most cases, make the direct recycling of these residues through
conventional agglomeration processes impractical.
EAF pollution abatement residue analyses from other sources are given
in Table 3.7-2. As expected, these data obtained from the literature
(since they represent a greater variation of EAF steelmaking practices)
show even a greater variation in chemical composition than those we
have obtained from four steel mills in the U.S. Respectively, the
total iron contents vary from 21.7 to 53.9%, the zinc content from
trace to 24.8%, and the lead content from trace to 2.7%.
The following table (Table 3.7-3) lists the results of our screen
analysis of the three dusts and the additional sludge samples to which
we had access:
Table 3.7-3 PARTICLE SIZE ANALYSES OF EAF RESIDUES
Plant
G
H
A
M
Fines
Dust
Dust
Dust
Sludge
Screen Sizing
-10 micf tins
79.6%
76.4
70.1
68.6
-20 microns
84.8%
83.9
78.5
73.0
-325 mesh
94
93
89
84
(44 microns)
.3%
.4
.6
.5
These results are somewhat coarser than those reported in a review
article on the "steel industry in-plant fines""'.
95
-------
The quantities of residues collected at the various sites are
presented in Table 3.7-4.
Table 3.7-4 QUANTITIES OF RESIDUES GENERATED
IN EAF OPERATIONS
Plant
A
B
C
H
Residue
Dust
Sludge a
Dust
Dust
Weighted Avg.
% of Steel Production
0.9
1.2
1.6
1.4
1.3
a Includes continuous casting and vacuum degassing
residues.
These values are in line with data given in the literature ' ' and
all are within the range of roughly 0.3 to 2.0% reported in a recent
international study . The airborne and waterborne residues
generated in electric arc furnace operations are presented in
Table 3.7-5 based on the aforementioned study.
Because of the limited sampling available to us, the figures we developed
relative to the disposal techniques in the plants we visited may not be
representative. We found that 56% of the collected residues are disposed
of as landfill, 38.4% was stocked and 5.6% recycled. The stocking is
being done at only one plant in anticipation of an on-site recovery
process in the construction stage at the time of our visit. The small
percentage recycled was. said to be going back to the electric arc
furnaces•
96
-------
Table 3.7-5 RAW RESIDUAL LOADS ASSOCIATED WITH EAF
(11)
STEEL MANUFACTURING PROCESS
Type of Discharge
Raw Residual Load
(kg/ton of steel)
EAF - Airborne
Particulates
EAF (Semi-wet) - Waterborne
Suspended solids
Fluoride
?H
EAF (Wet) - Waterborne
Suspended solids
Fluoride
Zinc
PH
3.0 - 20.0
0.8
0.01
6-9
3.5
0.02
0.02
6-9
The electric arc furnace operations in England, Germany and Japan also
have pollution control facilities. As in the U.S., both "wet" and
"dry" collection systems are used. The quantities of residues
generated in the different countries represent a wider range than the
quantities generated in the U.S. alone. The data obtained in Europe
fall between 5-20 kg/ton of raw steel and in Japan between 3.6-10 kg/
ton. However, the Japanese pointed out that when scrap high in zinc
(and lead) is used in combination with high scrap ratios, significantly
higher quantities (20-25 kg) of residue per ton of steel can
occasionally be generated.
97
-------
Because of the high tramp element content (zinc and lead), all of the
/ f\ \
EAF residues in England are dumped . The 49,000 tons* of EAF
residues generated per year contain 6,500 tons of zinc and 1,500 tons
of lead.
In Germany and Japan the residues are either recycled or stored. In
both countries special installations are used for the processing and
recovery of metal values from these wastes, and there are plans for
building a similar installation in England. For further details on
recycling, see Section 3.16, Recycling.
* From BSC operations: The private sector contributes about 10%
of the total tonnage of steel produced in England.
98
-------
3.7 REFERENCES - ELECTRIC ARC FURNACE
1) Annual Statistical Report for 1974. American Iron and Steel
Institute, Washington, D. C., 1975.
2) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
3) Hopkins, D. W., Johnson, W., and Davies, R. Constitution of Oxide
Fume from Steelmaking, Ironmaking & Steelmaking Quarterly
(British Steel Corporation) No. 1, 1974, pp. 25-29.
4) Barnard, P. G., et al. Recycling of Steelmaking Dusts. In:
Proceedings of 34th Mineral Waste Utilization Symposium, Chicago,
1972, pp. 63-68.
5) Powell, H. E., Dressel, W. M., and Crosby, R. L. Experimental
Metals Reclamation Process Recovers Alloys from Steel Mill Wastes.
33 Magazine, Vol. 13 (4), April 1974, pp. 48-50.
6) Cavaghan, N. J., and Traice, F. B. Utilization of In-Plant Fines.
JISI 208 (6), 1970, pp. 538-42.
7) Brinn, D. G. A Survey of the Published Literature Dealing with
Steel Industry In-Plant Fines and Their Recycling. U.S. Bureau
Of Mines NTIS PB-236-359, August 1974.
8) Dressel, W. M., Barnard, P. G., and Fine, M. M. Pre-Reduced
Pellets from Iron and Steelmaking Wastes. (Presented at AIME
Annual Meeting, Chicago, 1973, Prepring #73-B-72, U.S. Bureau of
Mines), pp. 12.
9) Lund, H. F. Industrial Pollution Control Handbook. McGraw-Hill
Book Company, New York, 1971.
10) Trace Pollutant Emissions from the Processing of Metallic Ores.
U.S. EPA, Washington, D. C., EPA 650/2-74-115, October 1974.
11) Organization for Economic Cooperation and Development, Environment
Directorate (Preliminary Draft), PCC/AEU/ENV/74.2, Paris, 1975.
12) British Steel Corporation. The Arisings and Treatment of BSC
In-Plant Fines. Swinden Laboratories, Moorgate, Rotherham. 1975.
99
-------
3.8 SUBCATEGORY: VACUUM DEGASSING
Degassing under high vacuum is a technique used to adjust the final
chemistry of steel in that period between tapping of the steelmaking
furnace and the commitment to either ingot or various steel casting
operations. This treatment effectively reduces hydrogen, oxygen and
carbon levels while at the same time permits alloying element
I
refinements
properties.
refinements . The net effect is cleaner steel with enhanced physical
Based on often contradictory industry estimates, 5-8% of the steel
produced in the United States was vacuum degassed in 1974. Most of
the vacuum degassing was made in connection with continuous casting
or large-piece steel casting operations.
While there are broad variations in means and equipment used for vacuum
degassing, they all fall under three rather broad classifications:
1. Stream degassing,
2. Ladle degassing, and
3. Recirculation degassing.
In all cases, either the process itself or supplementary means
(induction stirring or gas injection) are used to expose as much of the
steel surface as possible to the vacuum during the roughly one-half
hour degassing cycle. Superheating of the steel to 35-70° C above
normal furnace tapping temperatures is also a common practice. This
step,combined with preheating of the various vessels and equipment used
and/or providing auxiliary heat during the cycle, helps to make up for
heat losses during degassing and prevents premature skull formations.
In recent years, a new vacuum steelmaking technology, the VAR (vacuum-
arc-remelting) process was developed and can be added to the list of
vacuum steelmaking approaches. VAR is usually used for the manufacture
of high strength and alloy steels.
100
-------
Vacuum degassing systems range in capabilities from under one ton
per charge to over 300 tons. Vacuums in the 300-1000 micron pressure
range are required in the more common systems. These low pressures
are achieved with multi-stage steam ejectors. Condensed steam and
water from the barometric condenser, combined with exhaust gases are
the normal process wastes from this operation. The liquid wastes
will contain solid and dissolved constituents and the gaseous phase,
some partieulates and polluting gases.
Three of the eleven plants we visited had vacuum degassing facilities.
None reported any separate air pollution control residues for vacuum
degassing. Two of the three had water recycle systems. In these
facilities the residues (suspended solids) contained in the process
waters were removed in joint treatment facilities. The third facility
had a once-through water system with the water undergoing joint treat-
ment in deep bed filters with other process waters.
Since the residues from the vacuum degassing operations were not
collected separately (in the plants we visited), we were neither able
to collect samples for analyses, nor obtain information on the quantities
collected. However, it may be noted that the quantities of residue
collected from this operation are "very small." However, according to
(2)
the OECD Study , the quantity can vary from 0.1 to 16.0 kg/ton of
steel vacuum degassed.
(3)
According to information obtained through private communications ,
the chemical composition will vary with the type of steel degassed.
In some cases, besides the low iron levels, high manganese levels
(4)
were reported .
Neither in Europe (England and Germany) nor in Japan were the technical
institutions, government agencies and the steel mill personnel able to
supply information on the quantities or chemical composition of the
vacuum degassing residues. The reason for this lack of information
101
-------
was the same as in the U.S.: (1) the quantities of residues generated
are insignificant in comparison with other steelmaking or ironmaking
pollution control residues; (2) the residues are not collected
separately but treated jointly with other steelmaking residues, and
(3) there are no significant quantities of tramp elements in these
residues.
102
-------
3.8 REFERENCES - VACUUM DEGASSING
1) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
2) Organization for Economic Cooperation and Development.
Environment Directorate, PCC/AEU/ENV/75.2 (Preliminary Draft),
Paris, August 1975.
3) Unpublished data. Dravo Corporation Research Center.
4) Varga, J., Jr., and Lonnie, H. W. A Final Technological Report
on a Systems Analysis Study of the Integrated Iron and Steel
Industry. Battelle Memorial Institute, Columbus, Ohio.
103
-------
3.9 SUBCATEGORY: CONTINUOUS CASTING (CC)
One of the newer technologies for casting steel is continuous casting.
This is a one-step operation whereby molten steel is directly converted
to a semi-finished shape (slab, bloom, billet or, in some instances to
a strip or round) suitable for direct processing in secondary rolling
operations. This approach supplants and offers some distinct economic
and operating advantages over the conventional teeming, ingot stripping,
soaking pit, preheating and primary rolling operations . In 1974
approximately 12% of the raw steel produced in the U.S. was
(2)
continuously cast
In practice, molten steel is poured from the ladle into a tundish, an
intermediate pouring container, and thence into the top of an open-ended,
water-cooled cooper mold. This mold is of square, oblong or round
cross-section in line with the desired shape of the product to be cast.
As the molten metal solidifies, it is drawn out of the bottom of the
mold by and through roll sets and high pressure cooling water sprays.
Hot metal input, roll speeds and water spray rates are all inter-
controlled so that a continuous flow of solidified and shaped steel
product is achieved. Depending on the type of caster, the circuit may
also contain straightening rolls as well as a sizing roll stand(s) to
provide considerable versatility as to final product dimensioning.
This "endless" ribbon of steel then enters a cut-off station where it is
mechanically or flame-cut into convenient working lengths.
Air pollution is not a major problem in a continuous casting shop, being
largely limited to emissions during pouring and cut-off. However,
substantial quantities of water are required and some of this does pick
up solids (scale) and oil. In addition, many continuous casting shops
use one or more closed or semi-closed loop circuits for either or both
of their contact (process) and non-contact waters in which case the
cleaning of the non-contact waters add to or results in sludge which is
attributable to the operation.
104
-------
Three of the plants we visited had continuous casting facilities in
operation in 1974 and were able to provide some data as to the pollu-
tion control residues from these facilities. One additional mill had
a new continuous casting installation at the time of our visit with
insufficient data available for our study. The three plants from which
operating data were received are discussed in the following -
paragraphs.
Plant B - One closed loop water system (with blowdown) is used to
provide water for their electric furnace, vacuum degassing and continu-
ous casting shops. This circuit contains scale pits, chemical additive
tanks, thickeners and a cooling tower. The underflow from the thickeners
is vacuum filtered and the filter cake is landfilled. The continuous
casting shop is served by its own scale pit and the amount of scale
collected here is a little over 0.6% of the quantity of steel continu-
ously cast. This scale is sold as BF feed.
Plant G - This plant has both slab and billet casting facilities.
Process water for the slabbing unit is closed circuit with bleed. The
circuit includes a scale pit, cooling tower, filters and a clarifier.
The non-contact water for this slab operation is also closed loop with
a cooling tower and bleed to the process water system. The resultant
pollution control wastes are scale and sludge for the slab caster.
Contact and non-contact waters for the billet caster are closed loop
with the non-contact EAF water. This circuit consists of a scale pit,
sand filters and cooling tower. Scale and sludge result.
The total quantity of scale collected from both casting operations amount
to about 0.2% of the steel tonnage cast and is a negligible amount
(0.03%) of the total steel production at this plant. The combined
output of sludge is only 105 tons/year - again an insignificant residue.
The scale is "stocked" and the sludge landfilled.
105
-------
Plant K - Their multi-strand casting unit is served by two water circuits •
one open and one closed. The closed loop (presumably the non-contact)
water circuit contains flat and deep bed filters which yield only a
very small amount of sludge (185 tons/year). On the other hand, the
scale collected in the open contact water circuit comes to about 2.5% of
the total steel cast (roughly 0.3% of the steel produced at this plant).
The sludge is landfilled and the scale recycled.
In the English and German steel works no data were available on the
quantities of residues, scale or sludge produced.. In Japan 2.6 kg of
scale is generated per ton of steel cast. "Small quantities" of oil
containing sludge and scum are also generated in their casting operations,
but the quantities are not measured because they are jointly treated
with the other oily wastes, in their "oily waste disposal facilities"
and with the other sludges in their sludge treatment facilities. An OECD
(3)
study gives data on the raw residual loads generated in continuous
casting operations (Table 3.9-1).
Table 3.9-1 RAW RESIDUAL LOADS ASSOCIATED
(3)
WITH CONTINUOUS CASTING '
Type of Discharge
Raw Residual
Load
(kg/ton of steel)
Airborne residuals
Particulates
NA
Waterborne residuals
Effluent flow (lit./ton)
Suspended solids
Oil and grease
(pH)
(17,514)
0.9
0.5
(6 - 9)
106
-------
This study places the quantity of suspended solids at 0.9 kg/ton of
steel cast, in the process water, indicating again that the sludge
portion of the continuous casting residues is very small.
The collected scale is always directly recycled without further
treatment either through their plant, furnace operations, or through
sintering. The sludges and scums are also usually recycled but only
after they undergo one of the two previously mentioned waste treatment
and an additional agglomeration, mostly sintering, operation.
107
-------
3.9 REFERENCES - CONTINUOUS CASTING
1) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
2) Anonymous. Worldwide Continuous Casting Roundup - Part III.
33 Magazine, December 1975, pp. 42-47. (Calculated from
information contained in this article.)
3) Organization for Economic Cooperation and Development.
Environment Directorate, PCC/AEU/ENV/75.2 (Preliminary Draft),
Paris, 1975.
108
-------
3.10 SUBCATEGORY: ROLLING
Most of the steel produced in the open hearth, basic oxygen
and electric arc furnaces is tapped into refractory-lined ladles and
then "teemed" into cast iron molds to form ingots. However, today,
especially in more modern plants, the trend is toward continuous casting
of billets, -slabs and blooms. It is during this period from furnace to
ingot (or before continuous casting) that any final refining steps such
as chemistry adjustments and vacuum degassing are completed . After
partial or complete cooling, the mold is stripped from the ingot and
the ingot is placed in "soaking pits" for reheating(and heat treating)
in preparation for subsequent processing steps.
Ingots can vary widely in shape and weight depending, to a large extent,
on the end product desired and the rolling equipment available. Weights,
for example, can go from several hundred pounds (speciality steels) to
several hundred tons (large forgings). Most ingots, however, fall in
the 10 to 40 ton range and are intended for the production of the vast
quantities of mass-produced steel products that are needed in our
industrial society.
These products are made by passing the ingot through a succession of
pressurized rolls and forming operations which slowly and inexorably
reduce the cross-sectional area of the ingot to the final or near-final
shapes and forms desired. Most of this is done hot, followed, in some
cases, by further reduction in "cold rolling" mills. Many integrated
plants have associated specialized finishing mills which are generally
considered as part of their rolling operations since they are, in many
cases, integral with or natural continuations of their rolling operations.
Examples of the latter are pipe mills using semi-finished "skelp" or
billets as feedstock and wire and nail mills which reduce rod stock to
marketable finished products. Pickling and plating processes which may
also fall under the latter were considered as separate subcategories
for the purposes of this study.
109
-------
Although some steel is hot-rolled from ingot to final form in one
continuous operation, the normal approach is to do this in at least
two distinct steps. The first step in the conversion process is the
rolling of heated ingots into one of three intermediate shapes: slabs,
blooms or billets. Slabs are rectangular in cross section and are
intended for further rolling to plate or sheet. Blooms and the slightly
smaller billets are essentially square or oblong sections of lesser
cross-sectional areas than the slab. These pieces end up, for example,
as rails and structural shapes (blooms) or bars, rounds and wire
(billets).
After cooling, the blooms, billets and slabs are generally referred to
as semi-finished steel. At this time, they undergo '^conditioning" which
is nothing more than a thorough inspection followed by chipping,
scarfing and/or grinding to remove surface inperfections which might
affect the quality of the finished steel product. After the
conditioning, the semi-finished steel is ready for further hot working
by rolling or forging, coupled, in some cases, with cold working
operations that follow the secondary hot working. These final forming
and finishing operations are performed in a wide variety of mills
normally designated by some name descriptive of the operation being done,
i.e., hot plate mill, rod mill, bar mill, structural mill, etc. (These
designations are often prefixed with a sizing number in inches, which
roughly describes the roll stand used.) Interspersed throughout these
facilities are the secondary operations, such as tempering, annealing
and leveling, which are required to impart certain physical and new
metallurgical qualities to the final steel products.
In 1974 almost 110 million tons of steel products were shipped which
underwent usually more than one rolling operation before leaving the
mills. Table 3.10-1 shows the various steel products and the
quantities shipped in 1974.
110
-------
(2)
Table 3.10-1 SHIPMENTS OF STEEL PRODUCTS - 1974
(ALL GRADES, INCLUDING CARBON, ALLOY
AND STAINLESS)
Product
Semi-finished
Shapes and plates
Rails and accessories
Bars and tool steel
Pipe and tubing
Wire and wire products
Sheets and strip
Tin mill products
TOTAL net shipments
Tons
5,509,284
18,128,323
1.785,391
18,514,292
9,843,661
3,171,387
44,991,065
7,528,166
109,471,569
Although rolling or hot/cold forming are basic and sizeable operations
at most steel plants, these operations produce only a minor quantity
of airborne pollution. Most of this arises from the scarfing, grinding
and other surface preparation steps entailed in the conditioning of
the steel during its conversion from ingot to finished form. On the
other hand, rolling requires large quantities of water for roll and
material cooling, scale removal and flushing purposes. These waters
do become contaminated with oil and suspended solids.
From an air quality standpoint, six plants reported on fume and dust
collection residues at various conditioning steps. Table 3.10-2
summarizes this information.
While hot and cold rolling operations are similar, their liquid wastes
are different and are usually handled separately. There are a number
of reasons for this but basically they center around the fact that in
cold rolling, various oils and emulsions are used and cold rolling
111
-------
shops are generally contiguous with other cold finishing operations
(plating, pickling, etc.) that require more extensive waste water
treatment than that normally afforded hot mill effluents.
Table 3.10-2 RESIDUES COLLECTED IN ROLLING AIR POLLUTION
CONTROL FACILITIES
Plant
A
B
C
F
H
I
Operation
Scarfing
Grinding
Grinder-
Grinder
Scarfing
Scarfing
Grinder
Grit
blast
Scarfing
Collection
Equipment
Wet ESP
Baghouse
Mechanical
collector
Mechanical
collector
Mechanical
collector
Wet EPS
Baghouse
Baghouse
Wet
scrubber
Collected Residue
Nature
Sludge
Dust
Dust
Dust
Sludge
Sludge
Dust
Dust
Sludge
Quant . % of
Steel Produc.
Negligible
0.1
0.6
0.1
Unknown
Unknown
0.1
0.1
Unknown
Location and
Comments
Slab mill
Conditioning bldg.
Slab mill
Stainless steel
finishing mill
Slab mill -
residue with scale
Joint treatment
Billet mill
Blooming mill
Slab mill -
residue collected
with scale
Hot rolling and forming generate large quantities of iron-bearing
residues. These wastes, mainly scale and fine iron oxides, are flushed
out of the various mills along with the process waters used for
descaling, roll and material cooling and other purposes. The minimum
treatment provided consists of settling out the heavier and larger
suspended solids (scale) in adjacent scale pits or settling basins before
discharging the overflow. While some of the entrained oil adheres to
and is removed periodically with the scale, most of the oil is skimmed
or drawn from the water surface using one of many devices that can be
112
-------
attached to the pits for that purpose. The overflow from these pits
then goes on to subsequent treatment facilities where additional oil
and the finer solids are removed.
Table 3.10-3 lists the various hot mill water circuits used at the
eleven plants in our study. All had hot rolling operations although
only ten had cold forming shops. As noted, two of the plants provided
no treatment other than scale pits. Two plants had water recycle
systems and three others had similar loops on at least some of their
mills. In summary, all of the plants had scale pits and collected
their scale; four plants had their own individual treatment facilities
for final processing of their hot mill waste waters while five used
joint waste water treatment plants.
Table 3.10-3 WASTE PROCESS WATER TREATMENTS FOR HOT ROLLING
OPERATIONS
Plant
A
B
C
D
E
F
G
H
I
J
K
Water Recycle
Yes
X
X
No
X
X
X
X
X
X
Partial
X
X
X
Water Treatment Facilities
Scale
Pit
X
X
X
X
X
X
X
X
X
X
X
Settl.
Ponds
or
Basins
X
X
X
X
X
X
X
Clarif./
Thicken .
X
X
X
X
X
X
Chem.
Addit .
X
X
X
Sand/
Bed
Filters
X
X
Residue Coll.
Scale
X
X
X
X
X
X
X
X
X
X
X
Sludge
or
Filter
Cake
—
J
-
X
X
X
J
J
J
xa
J
NOTE: "J" denotes "joint residue"
a Joint with scale
113
-------
The total quantity of rolling residues is estimated to be approximately
(3)
7.4 million tons in 1974 . Of this, less than 200,000 tons is
estimated to originate from the cold rolling operations, leaving a
balance of roughly 7.2 million tons for the hot rolling (and
conditioning) residues.
Liquid wastes from cold rolling operations differ in two respects from
those generated by hot rolling. They contain little, if any, scale
or iron-bearing particulate but they are more heavily ladened with
oil and rolling emulsions. Consequently, scale pits are generally not
necessary in cold mill water circuits, but the emphasis is placed on
oil removal. Five of the ten plants we visited had closed, roll
lubricating fluid loops for all or some of their mills. Such circuits
not only conserve valuable lubricating compounds but also limit the
amount of spent oil and gook that must be discharged to the waste
process water system for subsequent treatment. The total quantity of
"pollutants removed" in the cold rolling operations of the U.S. steel
(4)
industry was estimated to be 148,600 tons in 1973 .
In all cases but one, cold mill aqueous wastes were treated jointly
with other waste waters, usually those from associated pickling and
plating operations. The exception was a closed loop water system with
waste water bleed discharge to a municipal treatment system after a
de-emulsifying operation to recover the oils. All of the others put
their joint wastes through settling stages (clarifiers or thickeners)
and/or filters (sand or deep bed) and/or lagoons. In six of the nine
instances, chemical additions were used to break up the emulsions and
to separate the solids.
The oil and oily sludges collected here as well as that collected in the
other treatment facilities throughout the plants were disposed of in
one of the following ways:
1) Used internally as tramp oil (road beds, dust suppressors,
miscellaneous fuels, etc.) or donated to outsiders.
114
-------
2) Reprocessed within the plant for reuse as fuel oil or lubricant.
3) Sold to outsiders for reprocessing.
The chemistry of pollution control residues resulting from rolling
operations would be expected to vary widely although basically
dependent on the steel grades being worked. Reuse of these wastes is
highly desirable since they are normally high in iron content and low
in tramp metallic elements such as lead and zinc. However, they
sometimes contain deleterious oil and grease residuals which can and
do often preclude direct recycling through sintering operations.
We used the basic sample data originally supplied for this study through
the AISI and supplemented this information with some additional
analyses (mainly total iron and oil/grease). During our plant visits
we also obtained some samples which we also analyzed. The data and
information gathered from these sources has been broken down into the
following categories which fairly well represent the three types of
rolling mill residues presently collected in the mills:
1) Conditioning residues - grinder and scarfing dusts or sludges.
2) Scale - collected from scale pits or primary settling basins.
3) Scale/sludge - resulting from secondary treatment of scale pit
aqueous effluents.
Table 3.10-4 presents the chemical data on conditioning residues from
four of the plants studied. Samples A, B, C and D, for example,
represent composite weekly samples taken over a four-week span and the
numbered sample analyses are individual day samples arbitrarily selected
from the weekly samples. Some sizeable variations in steel types
being rolled over these periods are obvious.
The quantities of scale collected in the scale pits at the various
plants varied considerably (i.e., between 18 and 102 kg/ton of steel
rolled (Table 3.10-5). The iron contents of the scale are high (57.7 -
115
-------
Table 3.10-4
CHEMICAL ANALYSES OF STEEL CONDITIONING RESIDUES
(weight %)
Plant
A
B
C
H
Sample
Grinder Dust A
B
Grinder Dust A
B
C
D
Grinder Bust 1
2
3
4
Grinder Dust C
Grinder Waste
A
B
C
D
Grinder Dust A
B
C
D
Fe
73.2
57.1
72.0
88.8
Zn
4001
.004
.002
.003
.002
.002
.004
.007
.004
.002
<.001
.085
.140
.310
.140
.005
.003
.005
.002
Pb
<;001
-------
Table 3.10-4 CHEMICAL ANALYSES OF STEEL CONDITIONING RESIDUES (continued)
(weight %)
Plant
H
Sample
Grit Blast
Dust A
B
C
D
Grinder Dusts
1
2
3
4
5
6
Fe
68.4
63.9
69.2
70.3
78.5
77.8
Zn
.005
.004
.004
.005
.004
.004
.006
.003
.006
.006
Pb
.005
.003
.004
.001
.010
.020
.020
.030
.006
.008
Sn
•
.02
.06
.03
.02
.04
.03
Al
.11
.11
.10
.07
.04
.04
Cu
.200
.050
.075
.050
.10
.09
.08
.06
.06
.06
K
.010
.010
.010
..006
.006
.010
Cr
.130
.001
.090
.003
Mn
.860
.016
.600
.300
Ni
.080
.020
.075
.030
Comments
Conditioning
shops
Conditioning
shops
NOTES: Lettered samples (A, B, etc.) are composite and consecutive weekly samples.
(Analyses performed by Calspan Corporation)
Numbered samples (1, 2, etc.) are individual day samples taken from the lettered
weekly samples (A, B, etc.).
-------
Table 3.10-5 SCALE COLLECTION AND DISPOSITION
Plant
A
B
C
D
E
F
G
H
I
J
K
Weighted Av
Scale
as % of Total
Steel Production
1.6
1.8
5.8
4.8
2.6
7.0
5.3
3.3
10.2
8.2
3.9
rg. 5'1
Disposition
Recycle - BF
Sold for BF and sinter
Recycle - sinter
Recycle - BF and sinter
Recycle - BF and sinter
50% stock/50% sold or
sinter
Stock
25% recycle/75% stock
Recycle - sinter
Recycle
Recycle - sinter
Disposition summary: Recycle 69.6%
Stock 29.7
Sale 0.7
118
-------
81.9%) and oil and grease levels generally lie in the 0.1 to 1.9%
range (Table 3.10-6a). Results obtained from the literature show
similar variations in iron content (Table 3.10-6b).
Table 3.10-6a IRON AND OIL CONTENT OF ROLLING
MILL SCALES
(weight %)
Plant
A
B
C
G
I
J
K
Mill
Primary
Slab
Hot strip
Blooming
Structural
Plate
Hot strip
Primary
Hot strip
Blooming
No. Samples
2
1
2
2
5
6
5
2
2
2
Total Fe
68.8 - 70.0
64.3
67.5 - 71.5
77.5 - 81.9
61.2 - 74.0
60.2 - 72.9
73.5 - 74.9
57.7 - 68.8
73.1 - 74.8
66.1 - 71.7
Oil
.01 - 1.0
0.1
.09 - 1.9
0.1
0.1 - 0.6
0.1 - 0.8
0.1 - 0.3
-
0.2
0.2 - 0.5
Rolling mill sludges resulting from treatment of the scale pit effluent
waters in two of the four plants visited not using joint treatment means
were examined and the results are given in Table 3.10-7. Iron levels
are somewhat lower, but oil/grease contents are substantially higher
than in scales. In both cases, these residues are landfilled.
The quantities of conditioning wastes generated in rolling operations
have been previously given in Table 3.10-2. Although these data are
somewhat meager, it would appear that these wastes would constitute no
more than 1 or 2% of the total quantity of waste generated at most plants
if they are collected separately and not included with scale figures.
Scale collections, on the other hand, can be quite sizeable (Table
3.10-5); with rather a large spread between the low and high percentages.
119
-------
Table 3.10-6b CHEMICAL ANALYSES OF ROLLING MILL SCALES (FROM THE LITERATURE)
(weight %)
Ref .
5
6
7
(R) 8
(R) 9
10
11
(R)12
Fe
63.0
73.9
73.0
73.0/
74.0
62. 6/
73.7
73.7
72.3
54. 3/
75.4
C
-
-
1*2
0.5/
0.7
0.01/
0.16
0.8
-
0.05/
7.11
S
2.0
-
-
0.02/
oa
O.Ol/
0.16
0.03
0.04
^
Pb
0.002
0.001
-
-
0.004/
0.014
-
-
o.oo/
0.04
Zn
0.004
0.005
-
_
0.003/
0.007
-
-
O.OO/
0.05
Mn
-
0.72
-
-
-
-
-
NagO
-
-
-
-
-
-
-
O.Ol/
0.09
K2°
-
-
-
-
O.Ol/
0.019
-
-
O.Ol/
0.09
A1203
1.9
0.50
-
0.5/
2.2
1.7
-
^
CaO
3.8
0.65
-
0.2/
1.8
O.I/
3.4
0.1
0;§
^
MgO
-
0.72
-
0.2
0.3/
1.1
-
0.2
~~
sio2
-
0.55
-
0.4/
1.9
0.2/
3.4
0.6
0.5
""•
to
o
(R) Range of all the results reported by the authors.
-------
Table 3.10-7 CHEMICAL ANALYSES OF HOT ROLLING MILL SLUDGES
(weight % dry basis)
Plant
J
F
Sample
A
B
C
D
1
2
3
4
1
2
1
2
Fe
-
-
-
-
72.5
72.5
70.3
61.0
66.2
64.9
69.7
65.9
Zn
.040
.033
.036
.036
.12
.07
.10
.11
.009
.01
.01
.08
^Pb
.009
.004
.004
.008
.005
.006
.010
.011
.01
.008
.02
.03
Sn
.015
.013
.013
.011
-
.03
.13
.12
Al
.11
.18
.88
.47
.003
.02
.01
.03
Cu
.015
.013
.014
.014
.01
.01
.01
.01
.003
.02
.01
.03
K
-
-
-
-
.12
.11
.01
.10
Cr
.016
.013
.014
.014
Mn
.230
.180
.185
.179
Ni .
.025
.020
.021
.020
F
.009
.004
.004
.008
Oil
11.4
10.0
11.9
12.2
7.4
13.9
30.4
33.1
Mill
Hot strip
Hot strip
Primary
Hot strip
NOTE: Lettered samples (A, B, etc.) are composite and consecutive weekly samples analyzed by
Calspan Corporation. Numbered samples are our analyses of day samples from the weekly
lettered samples, in the case of Plant J, and are samples we obtained in the case of
Plant F.
-------
The quantities of sludges generated from waste water treatment,
attributable to rolling operations, is difficult to discern, since six
of the nine plants have joint facilities or, as in one case, combine
these residues with their scale as an integral part of their
treatment circuits. The information we were able to gather is given
below (Table 3.1-8).
Table 3.10-8 QUANTITIES OF ROLLING MILL SLUDGES
GENERATED'-AND. THEIR DISPOSAL
Plant
D
E
G
J
Mill(s)
All
All
All
Hot strip
Sludge (% of
Scale Collected)
5
24
8
25
"•• Disposition
Recycle - sinter
Landfill
50/50 (landfill/
stock)
Landfill
Two of the six shops providing information on their conditioning residues
dispose of them as landfill, with the balance reporting reuse with
their scale. Roughly 70% of the scale is recycled to the sinter plant
or hot melt facilities; slightly less than 30% is stocked for future
recovery or dumped and less than 1% is sold. As noted above (Table
3.10-8), only a small portion of the generated sludge is reused at present,
In Europe and Japan, essentially the same pollution control methods are
used in the treatment of hot and cold rolling wastes and effluents as
in the U.S. Scale pits, oil skimmers and clarifiers in combination with
chemical treatment are typical for hot rolling operations. However,
large settling basins and/or ponds are also employed in some cases as a
final residue removal step. The clarified water is recycled almost
without exception.
122
-------
While scale pits are seldom found in cold rolling operations, so-called
"buffer pits" are. The small amounts of settled solids from these pits
are usually handled jointly with the sludges generated in the related
subsequent treatment steps where emulsion breakers and flocculants are
used.
In most cases, the oily waste residues from the skimmers and emulsion
breaking operations are sent to special waste oil treatment facilities
where the oils are recovered either for their original application
(i.e., rolling lubricant) or for fuel. In some cases, the waste
oil and scum is sold to, and the oil and fats recovered by, an outside
contractor. Some mills in Japan use their scum in their in-plant
incinerators as a fuel to help burn their rubbish.
The quantities of scale and sludge generated in the rolling operations
of the various countries differ somewhat (Table 3.10-9).
Table 3.10-9 QUANTITIES OF RESIDUES GENERATED IN
ROLLING OPERATIONS BY COUNTRIES
United States
Germany
England
Japan
kg/ton of Raw Steel
Scale a
16 - 102
15 - 75b
22 - 58
26 - 40C
Sludge
0.1 - 1.9
1-2
2-3
0.3 - 1
a Including conditioning residues.
b Kg/ton of rolled steel.
c Based only on the data obtained from Japan's
three largest (all>10 million tons/year
capacity) mills, producing large % heavy gage steels,
123
-------
The residual loads associated with the hot and cold rolling operations,
based on
3.10-10.
(13)
based on a recent international study , are presented in Table
As in the U.S., the larger-sized particles (^5 mm in England, ^>8 mm
in Germany) are recycled directly through the blast furnace operations
and the exceptionally large particles (J> 50 mm) through steelmaking
furnaces, while the fines (^5 mm) are recycled through sintering
operations. In the three large Japanese mills, all rolling mill
residues are recycled through sintering.
*
While in the U.S., 69-6% is recycled (and 0.7% sold), in England 87%,
in Germany 95-98%, and in Japan almost 100% is recycled. The
balance in England and Germany, as in the U.S., is usually "stored,"
with the exception of some oily sludges which are dumped. (In Japan
the dumping of oily sludges in most districts where the steel mills
are located is not permitted and, therefore, after an extra de-oiling
treatment, even these fines are recycled.)
* Based only on information obtained from the 11 mills visited
during our study.
124
-------
Table 3.10-10 RAW RESIDUAL LOADS ASSOCIATED WITH THE HOT
(13)
ROLLING AND COLD FINISHING OPERATIONS
Type of Discharge
Raw Residual Load
(kg/ton)
Hot Rolling
Cold Finish.
Airborne residuals
Particulates
Sulfur dioxide
Aerosols
0.4 - 3.5
1.0 - 4.0
,3.0 - 7.0
2.0 - 4.0
Waterborne residuals
Primary breakdown mill and cold rolling
(effluent flow, lit./ton)
Suspended solids
Oils and emulsions
Pipe and tubing mill
(effluent flow, lit./ton)
Suspended solids
Oils and emulsions
Plate mill
(effluent flow, lit./ton)
Suspended solids
Oils and emulsion
Bar mill
(effluent flow, lit./ton)
Suspended solids
Oils and emulsions
Wire and wire products mill
(effluent flow, lit./ton)
Suspended solids
Oils and emulsions
Hot rolled sheet mill
(effluent flow, lit./ton)
Suspended :solids
Oils and emulsions
(4,090)
2.0
0.5
(10,000)
3.5
0.7
(9,175)
3.0
0.6
(15,000)
3.5
0.7
(10,000)
3.5
0.7
(40,000)
4.1
0.8
0.5 - 1.5
0.8 - 1.2
125
-------
3.10 REFERENCES - ROLLING
1) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
2) Annual Statistical Report for 1974. American Iron and Steel
Institute, Washington, D. C,, 1975-
3) Pasztor, Laszlo. Problems of Resource Recovery in the Iron and
Steel Industry. In: Proceedings of the Fourth Annual Industrial
Pollution Conferences, WWEMA, Houston, Texas, March 1976.
4) Pollution Abatement Costs and Expenditures - 1973. U.S. Dept.
of Commerce, Bureau of the Census, Series MA-200(73)-2,
Washington, D. C., 1976.
5) Anonymous. Recycling of Steel Plant Waste Materials. Steel
Research, British Steel Corporation, 1974.
6) Goksel, M. A. Recovery of Iron, Zinc and Lead from BOF Dust and
Other Steel Plant By-Products. In: TSM-AIME Itonmaking
Proceedings, 30, 1971, pp. 126-145.
7) Barnard, P. G., et al. Recycling of Steelmaking Dusts. In:
Proceedings of 3rd Mineral Waste Utilization Symposium, Chicago,
1972, pp. 63-68.
8) Cavaghan, N. J., and Traice, F. B. Utilization of In-Plant Fines.
JISI 208 (6), 1970, pp. 538-542.
9) Brinn, D. G. A Survey of the Published Literature Dealing with
Steel Industry In-Plant Fines and their Recycling. NTIS,
PB-236-359, August 1974.
10) George, H. D., and Boardman, E. G. The IMS-Grangcold Process for
Agglomerating Steel Mill Waste Material. Grange Ore News,
October 1973, pp. 13-21.
11) Wetzel, R., and Meyer, G. Processing of Steel-Works Dust and
Slurry. ISI Publ. 139, Operation of Large BOF's, 1974, pp. 44-51.
12) British Steel Corporation. The Arisings and Treatment of BSC
In-Plant Fines. Swinden Laboratories, Moorgate, Rotherham, 1975.
13) Organization for Economic Cooperation and Development. Environment
Directorate, PCC/AEU/ENV/75.2, Preliminary Draft, Paris, August
1975.
126
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3.11 SUBCATEGORY: PICKLING
The hard, black oxide scale formed on the steel as a result of the
basic hot-forming operations, including hot rolling, can be a trouble-
some problem and must be removed before many of the subsequent hot
or cold finishing steps. This scale can adversely effect surface
appearance, die and roll wear, dimensional uniformity, and the ability
to coat and plate the steel. Pickling, the removal of scale (and in
some cases of rust) through the use of acid solutions, is the operation
universally employed in the mills to clean the surface of the steel
before further or final processing of steel.
Pickling can be performed in various ways: from pure batch to semi-
and continuous operations. In any event, the steel to be de-scaled
(or surface activated) is first immersed in an acid bath(s) for
some suitable period of time and then removed and subsequently washed
or rinsed with water to remove the residual acid. The combination of
acid bath(s) and rinse or post treatment stations constitute the
essential elements of the industrial "pickle line."
The most commonly used acids are sulfuricO^SO^) and hydrochloric (HCL)
with the latter being more popular in recent years^ . In use, they
are diluted with water to levels which, in combination with a suitable
operating temperature, provide the greatest acid activity. For example,
12 to 25% H2S04 concentrations at 93-105°C (200-220° F.) in continuous
pickling applications. Agitation of the bath with respect to the work,
or vice versa, is generally used to optimize the pickling operation.
De-scaling during pickling and removal of rust is accomplished at the
expense of the acid; the free acid content decreases with time and the
build-up of metallic salts in the bath increase to such an extent that
the pickling acid can no longer function efficiently. At this point,
the acid must be replaced or replenished with a fresh solution and
spent acid, commonly referred to as "pickle liquor," must be withdrawn
from the system and disposed of. Similarly, the effectiveness of the
127
-------
wash/rinse solutions becomes Impaired with times (usually because of
increase in dissolved solids content and acidity) and they, too, must
be replaced or replenished. As a consequence, the usual pickling
operations (batch or continuous) result in two process waste
effluents: spent pickle liquor and acidic rinse waters. Both can be
difficult to dispose of. (However, in some cases, spent pickle liquor
is used in municipal waste water treatment .)
Table 3.11-1 lists the various acids used in the pickling operations
at the plants we visited, together with the disposition of their spent
liquors. In-plant pollution control residues are generated at only
three locations: Plants B, D, and K. Plant B treats their wastes
acids along with their rinse water in a joint treatment facility.
Details on this facility and the resultant waste are given in the
discussion under subcategory 14, Waste Water Treatment Plants. The
other two plants (D and K) have acid regeneration (HC1) systems that
result in an iron oxide by-product. Plant D reports that this high
purity oxide amounts to about 5 kg/ton of processed (pickled) steel.
All but 6% of this "waste" is sold, primarily to the magnetic tape
industry. The unsold portion is landfilled because of high chloride
content. Plant K did not have reliable figures available as to the
quantity of oxide their regeneration operation produces but they sell
all that they make.
In most of the plants where an actual pollution control residue results
from the treatment of waste rinse waters, the resultant sludge is produced
as a joint waste water treatment sludge (Table 3.11-2). These
particular circuits are also covered under Subcategory 14, Waste Water
Treatment Plants. Plant E has a wire mill pickle rinse water that is
separately neutralized and settled, but their sludge is "impounded"
at the same location as the sludge resulting from the joint treatment
of their other waste rinse waters. Plant G uses a specially designed
128
-------
Table 3.11-1 ACIDS USED AND METHODS OF SPENT LIQUOR DISPOSAL
Plant
A
B
C
D
E
F
G
H
I
J
K
Acids Used
H2S04
H2S04, HN03, HF
H2S04
HCL
H2S04 , HC1
H2S04
H2S04 , HC1
H2S04
HC1
HC1
HC1
Disposal of Spent Liquor
Neutralized/outside contractor/landfill
Neutralized and lagooned/joint sludge to
landfill
Neutralized/outside contractor/landfill
Regener at ion
Reuse internally or deep well
Outside contractor/conversion to FeCL3
Deep well
Outside contractor/deep well
Sold (for processing) or deep well
Slag pile
Regeneration
Table 3.11-2 DISPOSITION OF WASTE PICKLING RINSE WATERS
Plant
Disposition of Acid Wash/Rinse Waters
A
B
C
D
E
F
G
H
I
J
K
No information
Neutralized and lagooned/joint sludge to landfill
Neutralized and discharged to stream
Lagooned/joint sludge to landfill
Neutralization/clarification/joint impoundment
Neutralized/to municipal treatment plant
Deep well and lagooned/joint sludge to landfill
Chemical treatment/joint sludge to storage
Chemical treatment/joint sludge to storage
Neutralized/joint sludge to landfill
Neutralized/lagooned/joint sludge to landfill
129
-------
rinse water process on one of their pickling lines that greatly reduces
the quantity of this water required. Consequently, they are able to
dispose of the smaller amount of "bleed" from the system in the deep
well where they also dispose of their waste liquor.
Typical chemical analysis of pickling sludges was reported by the In-
Plant Fines Group of the British Steel Corporation^ (Table 3.11-3).
Table 3.11-3 CHEMICAL ANALYSES OF PICKLE SLUDGE
(1)
Plant
1
••1
3
Total Fe
44.5
10.2
23.7
C
4.3
0.1
2.95
Zn
0.17
0.03
0.01
Pb
0.09
0.04
0.03
Na20
0.03
0.02
0.05
K20
0.07
0.02
.002
In Germany and Japan regeneration of the waste hydrochloric acids and
recovery systems for used sulfuric acids are common practice. None
of the mills in these two countries generated any pickling pollution
control residues with the exception of small quantities arising in the
rinse water neutralization operations.
In the acid regeneration processes iron oxide powder (from the hydro-
chloric acid regeneration) and the iron sulfate heptahydrate crystals
(from the sulfuric acid recovery systems) are produced as by-products.
In Japan one mill also produces iron chloride as a by-product. All of
these by-products are sold. However, the iron oxides are balled and
used as an ironmaking charge in the blast furnaces when, occasionally,
the purity of the oxides do not meet customer specificiations. The
only pickling residue dumped in Germany and Japan is part of the
rinse water neutralization sludges. In some Japanese plants only 10%
of the neutralization sludges are dumped while 90% are sold as raw
(4)
material for cement manufacture
130
-------
In England where the regeneration of waste pickling acids is also
gaining ground, the total quantity of pickling operation sludges at
the British Steel Corporation is relatively small. It was estimated
to be approximately 26,000 tons per annum, of which 41% was recycled,
34% sold and only 25% dumped or stocked for future recycling.
The various regeneration processes for sulfuric acid ' ,
. . . . , .,(8,9,10,11,12) . . .,(13,14)
hydrochloric acid , nitric-hydrofluroic acid ,
and waste pickling acids will be briefly covered in Section 3.16,
Recycling.
131
-------
3.11 REFERENCES - PICKLING
1) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
2) British Steel Corporation. The Arising and Treatment of BSC
In-Plant Fiens. Swinden Laboratories, Moorgate, Rotherham, 1975.
3) Private communication. Verein Deutscher Eisenhuttenleute.
4) Private communication. The Japan Iron and Steel Federation.
5) Reicher, Hans. Closed Loop Regeneration of Waste Pickle Liquor.
Iron and Steel Engineer, May 1975, pp. 47-49.
6) Dravo-Lurgi. Sulfuric Acid Recovery Systems. Dravo Corporation
Bulletin 74WWT03, Pittsburgh, Pa., 1974.
7) Seyler, J. K., et al. Sulfuric Acid and Ferrous Sulfate
Recovery from Waste Pickle Liquor. U.S. Environmental Protection
Agency EPA-660/2-73-032, Washington, D. C., January 1974.
8) Dravo-Lurgi. Hydrochloric Acid Regeneration Systems. Dravo
Corporation Bulletin 74WWT02, Pittsburgh, Pa,, 1974.
9) Burteh, J. W. Hydrochloric Acid from Industrial Waste Streams -
The PORI Process. CIM Bulletin, January 1975, pp. 96-99.
10) Schuldt, A. A. Regeneration of Hydrochloric Acid Pickle Liquors
at Stelco's Hilton Works. CIM Bulletin, February 1974, pp. 82-88.
11) Conners, A. Hydrochloric Acid Regeneration as Applied to Steel and
Mineral Processing Industries. CIM Bulletin, February 1975,
pp. 75-81.
12) Rupay, G. H., and Jewell, C. J. The Regeneration of Hydrochloric
Acid from Waste Pickle Liquor Using Keram-Chemic/Lurgi Fluidized-
Bed Reactor System. CIM Bulletin, February 1975, pp. 89-93.
13) Muhlberg, Heinz, et al. The Pickling of Alloy Steels with the
Aid of a Regeneration Plant for Mixed Nitric and Sulfuric Acids.
Stahl und Eisen 95 (14), July 1975, pp. 639-642.
14) Dempster, J. H., and Bjoerklund, P. Operating Experience in
Recovery and Recycling of Nitric and Hydrofluoric Acids from Waste
Liquors. CIM Bulletin, Feburary 1975, pp. 94-98.
15) Leary, R. D., et al. Phosphorus Removal Using Waste Pickle Liquor.
Journal Water Pollution Control Federation #46, 1974, p. 284.
132
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3.12 SUBCATEGORY: PLATING AND COATING
The utility of many basic steel products (sheets, strips, plates,
wires, etc.) depends on the application of additional surface treatments,
coating or plating. These surface treatments extend the life of the
steel under conditions of storage, exposure , to various environments
and end-use, although aesthetic considerations are also often of
considerable importance. Some of these supplementary treatments
(galvanizing, tinning and chrome-plating, for example) are routinely
associated with the finishing operations in the mills. Most of the mills
covered in our study had one or more of these metallizing and/or
similar coating operations.
According to the AISI Annual Statistical Report , of the 109,471,569
tons of "steel shipped in 1974," 5,549,389 tons (or 5.1%) was tin-
coated, 6,105,109 tons (or 5.6%) galvanized (zinc-coated), and
997,759 tons (or 0.9%) received other metallic coatings. Smaller
additional quantities received various chemical (and/or lubricating)
coatings.
Both in the tinning and galvanizing operations, hot-dip and electrolytic
coating methods are used. The tinning operations in the U.S. are
overwhelmingly electrolytic, although in some foreign countries hot-
(2)
dipped tin plating is still used to a considerable extent . On the
other hand, the galvanizing (zinc plating) operations were almost 95%
hot-dip operations in the U.S. Tin and lead mixtures (usually 20%
tin and 80% lead) are also used to coat steel sheets, producing
so-called terne sheets ("long-terne sheets") and terne plates.
None of the mills we visited reported any pollution control residues as
a result of their coating and plating facilities. The aqueous wastes
from the cleaning and pickling ahead of the coating baths are handled
as indicated in the discussion under Subcategory 3.11, Pickling,
Sludges, dross and waste coating/plating solutions are considered to be
process wastes as are those from any post-treatment operation used to
133
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provide special surface finishes. Most metal-bearing wastes are
returned to the supplier for reprocessing and metal recovery, while
some is still disposed as landfill. Other liquid wastes are generally
handled along with the acid rinse waters from pickling or discharged
directly to a lagoon or final treatment plant. The management and
disposal of the residues from these operations was discussed in
Subcategory 3.11, Pickling, or will be discussed in Subcategory 3.14,
Waste Water Treatment Plants.
Neither in Europe nor in Japan were any of the iron and steel industry
pollution control experts whom we uad contact with aware of any
residues arising in pollution control facilities of their metallic
coating operations. The metal-containing process wastes either are
sold or recycled by the metal suppliers. The process waters from the
cleaning, including pickling operations, are usually jointly treated
with the wastes from the pickling or rolling operations. In one
Japanese coating operation, the oily effluents are treated in their
(3)
"oil-containing waste-water disposal facility" and after the rem
of the oil and some suspended solids the water is recycled.
134
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3.12 REFERENCES - PLATING AND COATING
1) Annual Statistical Report ffor 1974. American Iron and Steel
Institute, Washington, D. C., 1975.
2) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
3) Private communication. Nippon Steel Corporation, Kimitsu Works,
1975.
135
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3.13 SUBCATEGORY: BOILERHOUSES
Raw and finished steel production requires sizeable quantities of
electric power. Traditionally, those steel plants containing
blast furnace and coke forming operations have provided a part of their
requirements with in-plant steam-powered generating facilities.
Coke and blast furnace gases supplemented by oil, natural gas and coal
have been the fuels used. Until recently, the trend had been away
from coal in an effort to prevent undue air pollution, but with the
new energy situation, the trend is reversed and it is expected that
in the future more coal will again be used than in reeenfc years.
Generating plants utilizing gaseous or liquid fuels yield essentially
no solid residues unless they are treating their exhaust gases to
remove SO . None of the plants in this study were doing so. Those
plants using coal produce bottom ash or clinker which is, strictly
speaking, a process waste, and fly ash which is usually a control
residue since most plants have at least rudimentary collection systems
to remove these particulates from their exhaust gas streams. Fly
ash is high in silica and alumina with only a minor iron content of
about 15% (dependent on coal used). As such, fly ash would not
figure prominently, if at all, in any steel plant waste recovery system.
Typical fly ash analyses are given in Table 3.13-1.
Only three of the visited plants reported one or more coal-burning
boilers. All of these were equipped with dry centrifugal collectors of
the multiclone or rotoclone type. The balance of the plants either
specifically indicated no coal usage or no pollution control residues.
Collected fly ash in all cases was combined with the bottom ash and
disposed of as landfill.
The residues in flue gas desulfurization (FGD) are usually the Ca or
Ca-Mg sulfite-sulfate type sludges (Table 3.13-2). In other systems
(se-called recovery processes), in place of (throw-away) FGD sludges,
136
-------
by-products, such as elemental sulfur, gypsum, ammonium sulfate, or
sulfuric acid, are produced in the pollution control facilities.
Table 3.13-1 CHEMICAL ANALYSES OF FLY ASHES FROM
SOUTHWESTERN PENNSYLVANIA AREA
(weight % - dry basis)
CaO
MgO
Total sulfur
Si00
2
A12°3
Fe203
Na.O
2
K20
Ti00
2
Range
0.2 - 6.1
0.4 - 1.2
0.1 - 1.8
20 - 45
16 - 40
8-33
0.3 - 0.6
1-33
1-2
The by-products are not considered as pollution control residues,
neither in the iron and steel industry nor in the power generating
industry.
The FGD sludges, if the fly ash is not removed prior to the SO
scrubbing, contain various quantities of fly ash besides the calcium
(and magnesium) sulfite-sulfate precipitate, and, in some cases,
limestone or "free lime."
The quantity of FGD sludge produced in the desulfurization of flue
gases will depend on the sulfur content of the coal burned. For
each percent of sulfur in the coal, approximately 40 kg/ton of coal
137
-------
(dry basis) or 80 kg/ton of coal sludge Is produced
(1)
not counting
the weight of the fly ash, that may be co-recovered with the sludge.
The disposal of the large quantities of FGD sludges generated,
especially when coals with higher sulfur contents are burned, can be
a problem because of the difficulties in the dewatering and the
thixotropic properties of these sludge". However, at least two
types of FGD sludge stabilization processes are already used in full
scale power plant operations by the electric power generating
(2 3)
industry. One of them is the Calcilox - Synearttr ' and the other
the Poz-0-Tec process
(4)
Table 3.13-2 CHEMICAL ANALYSES OF LIME AND LIMESTONE
FGD SLUDGES
(weight % - dry basis)
CaO
MgO
Total S
so2
so3
co2
Free C
Si02
M2°3
Fe2°3
Na2°
K2°
Lime
Aa
43.4
.01
20.0
29.2
13.6
7.1
2.8
.58
1.21
.39
.35
.03
Free base
as CaO
.06
Ba
43.8
22.9
45.8
0.0
1.0
0
.18
.39
.29
.09
0
0
Limestone
C a
25.6
1.2
8.4
11.6
6.4
30.0
1.8
1.4
.59
.27
.52
.14
—
Lime
D b
18.1
2.4
7.2
12.1
2.9
3.2
31.6
18.3
4.3
.3
Limestone
E-tb
25.6
1.2
10.9
10.8
13.6
2.2
.14
21.3
11.3
5.6
.76
.98
.06
a Fly ash removed prior to S02 scrubbing (A, B, C)
b Fly ash co-removed during S0? scrubbing (D, E).
138
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3.13 REFERENCES - BOILERHOTJSES
1) Pasztor, Laszlo, Selmeczi, J. G-, and Labovitz, C. Stack Gas
Desulfurization Residue Management. In: Proceedings of National
Conference on Management & Disposal of Residues from Treatment of
Waste Waters, Washington, D. C., February 1975.
2) Selmeczi, J. G., and Elnaggar, H. A. Properties and Stabilization
of SCL Scrubbing Sludges. In: Proceedings of Coal and the
Environment Meeting, National Coal Association, October 1974.
3) Calcilox for Sludge Stabilization. Dravo Lime Company Bulletin
75DL02-3M, Pittsburgh, Pa., 1975.
4) U.S. Congress, Committee on Interstate and Foreign Commerce.
Hearings, Clean Air Act Amendments - Part 2. Serial No. 94-26,
Washington, D. C., 1975-
139
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3.14 SUBCATEGORY: WASTE WATER TREATMENT PLANTS
Most of the dry residues collected in iron and steelmaking plants are
the results of air pollution controls and can, like many of the wet
residues, usually be directly related to a specific iron or steelmaking
operation, shop or facility. Some of the wet wastes, however, result
from joint waste water treatment facilities (i.e., in which effluents
from more than one steel mill operation arejointly treated). Therefore,
it is difficult or impossible to assign these residues to any specific
iron or steel mill operation. This heading (subcategory) was siet up
to cover and account for just such (mixed) pollution control residues.
All but two of the plants we visited had one or more waste water :
treatment plants that yielded residues that did not logically fall
within the context of the various other subcategories in this study.
These treatment facilities varied in complexity from nothing more than
settling ponds or lagoons to one inter-connected series of three
individual treatment systems feeding one final lagoon and producing
but one common residue. Schematics of these treatment circuits as
they were given or described to us are shown in Figures 3.14-1 through
3.14-IX. These drawings may not be complete or factually correct in
all instances since we emphasized the arising and management of the
residues in our discussions of the various plants rather than the exact
and sometimes proprietary means used to generate these wastes.
There are several things to be noted about these treatment plants. In
all but one case they represent the final clarification step before the
effluents are discharged from the plant or the water is reused. For
another, the inputs are primarily finishing operation (coating, cold
mill, pickling, etc.) waste waters combined with the secondary effluents
from other plant treatment facilities such as settling tanks, clarifiers,
etc., in the iron and steelmaking operations.
140
-------
The chemistries of the sludges (Table 3.14-1) from these plants
testify to the variety and nature of their inputs. Iron contents
range from roughly 10% to a little over 40%. Oil contamination is
high in all cases and this alone precludes recycling of these wastes
in the normally practiced means without an intermediate oil removal step.
Tramp element content, principally Zn, is also high in many instances,
again making the recycling of these wastes through customary sintering
operations impractical.
The quantities and dispostion of these sludges are given in Table
3.14-2. With the exception of Plant B, the amount of these wastes is
not large compared to, say, scale or iron/steelmaking residues, but is
significant in the overall picture. The rather substantial amount of
Plant B sludge is due, as noted in the schematics, to the inclusion of
all of the hot rolling process waters in this treatment plant.
Landfill is the predominant method of disposing of these wastes with
six of the nine plants using this approach. Two plants stock these
residues. The remaining plant recycles the "scale" portion of their
waste (about 4% of their total scale collection) which is collected in
scalping tanks while landfilling the remaining portion collected in the
large settling tanks.
The waste water facilities in England, Germany and Japan are similar
in several installations to those used in U.S. steel works. Most of
the joint waste water treatment installations are serving more specific
purposes than those described under the U.S. operations. In all three
huge steel plants in Japan and in one works in Germany which we visited,
special oily waste water treatment facilities are used for the removal
of oil from the waste waters and slurries. In this way, the residues
freed from oil became suitable for and are recycled. However, when
no such special facilities are available, the waste water treatment
plant residues are dumped or "stored" as in the U.S.
141
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Table 3.14-1 CHEMISTRIES OF WASTE WATER TREATMENT PLANT SLUDGES
(Weight % - Dry Basis)
Plant
B
D
E
F
H
I
J
K
a
Sample
B-l
B-2
D-l
D-2
E-l
, F-l
H-l
1-1
J-l
K-l
K-2
Zn
.081
.049
.011
2.79
0.41
0.40
0.81
0,49
0.75
0.92
0.96
0.12
.066
.061
.070
.070
1.80
1.27
3.51
I
0.12
Pb
.003
.003
.007
0.21
0.04
0.01
0.14
0.12
.040
.053
.051
.063
.024
.023
.020
.023
.010
.013.
.011
Sn
-
-
-
0.05
-
0.07
0.24
0.16
.040
.035
.039
.035
.145
.162
.176
.189
.019
.019
.020
Al
0.29
0.26
0.50
3.12
1.26
0.88
0.67
0.69
0.67
0.77
0.59
0.73
0.34
0.36
0.35
0.36
3.07
2.13
3.32
nsuffic, ie
.047
0.11
6.2
Cu
0.02
0.03
0.02
-
-
-
0.04
0.06
.020
.026
.035
.042
0.01
0.02
0.01
0.01
.005
.006
.004
K
0.03
0.07
0.04
0.73
0.60
0.73
0.21
0.17
0.45
0.47
0.36
0.44
-
-
-
-
51.3
50.4
60.2
Na
-
-
-
-
-
-
-
-
.020
.017
.018
.016
-
-
-
-
.008
.013
.011
nt Sample
-
2.5
.048
Si02
2.48
1.96
-
-
-
-
-
-
4.89
5.65
5.11
5.70
-
-
-
-
2.09
3.29
2.97
s
34.9
Oil
3.4
9.8
-
6.71
1.10
14.9
85.9
38.1
3.9
4.5
6.2
8.0
6.2
6.5
8.2
8.3
16.5
26.0
15.9
4.6
Tot.
Iron
16.0
25.1
-
20.2
26.6
15.3
22.2
23.0
34.0
39.7
43.2
43.4
45.1
40.1
40.1
39.8
37.5
38.6
32.0
10.7
11.8
21.8
a Sample number refers to sample designations on respective waste
water treatment plant schematics.
142
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Table 3.14-2 QUANTITIES. AND DISPOSITION OF WASTE WATER
TREATMENT PLANT SLUDGES
Plant
B
D
E
F
G
H
I
J
K
Waste
Sample
No.
B-l
B-2
D-l
E-l
F-l
None
None
H-l
1-1
J-l
K-l
K-2
Nature
of Waste
Sludge
Filter cake
Sludge
Filter cake
Oily sludge
Scale
Sludge
Filter cake
Sludge
Sludge
Sludge
Sludge
Quantity
(as % of total
steel produced)
2.6
0.7
0.4
0.6
0.1
0.20
0.15
0.3
0.7
0.2
0.1
0.6
Disposition
Landfill
Landfill
Landfill
Landfill
Landfill
Recycle
Landfill
Stock
Stock
Landfill
Landfill
Landfill
143
-------
Slab Mill
Scale
Additivi
CJarifiers
Hot Mills
Scale
Cooling
Tower
Additives
To Stream
Clarifiers
Lagoons
Cold Mills
Pickling
Coating
Neut.
Tanks
Surge
Tank
Processing Plant
Sludge
(Sample B-l)
Neut.
Tanks
— *•»
Flocc.
•'_ Tank
Clarifiers
To
Stream
| Filter |-
Cake
(Sample B-2)
Figure 3.14-1 WASTE WATER TREATMENT PLANT SCHEMATIC - PLANT B
144
-------
Coking
Blast Furnaces (thickener overflow)
EOF
Pickling
Galvanizing
Cold Rolling
Boiler Slowdown
Hot Mill Slowdown
I N
Holding Pond
"Oil Boom
Sludge
(Sample D-l sludge)
(Sample D-2 settled
solids from biennial
dredging)
Oil Boom
Figure 3.14-11 WASTE WATER TREATMENT PLANT SCHEMATIC - PLANT D
145
-------
Cold Rolling
Cleaning
Strip Pickling
Elect. tinning
Galvanizing
Wire Galvanizing
BATCH CHROME TREATMENT
Elect. Tinning
Galvanizing
Storage
Tank
Reaction
Tank
Additives
Lagoons
H
Mixing Tanks
Filter
Clarifiers
Cake
(Sample E-l)
Coking
BF Slowdown
BOP Slowdown
Hot Rolling Slowdown
Galvanizing
Final
Effluent Pond
To Stream
Sludge (not yet dredged)
Figure 3.14-III WASTE WATER TREATMENT PLANT SCHEMATICS - PLANT E
-------
Oil &
Alkali Waters
from rolling
mills
Miscell. Wastes
Chem. Feed
Float/Sink Oil Separator
Oil
Waste
Sludge
(Sample F-l)
Air & Ghem. Feed
Clarifier
Sludge
Reclaim Water
Figure 3.14-IV WASTE WATER TREATMENT PLANT SCHEMATIC
PLANT F
147
-------
Non-contact Coke Plant
Pickle Rinse
Cold Mill
Hot Mill
BOF Slowdown
BF Slowdown
Scalping
Tanks
Scale
Settling
Basin
Sludge
To Stream
Figure 3.14-V WASTE WATER TREATMENT PLANT SCHEMATIC
PLANT G
148
-------
Filter
Cake
(Sample H-l)
Wire Mill
CCA
Finishing & Tube
Mill Slowdown
Acid Rinse
Hot Mill Filter
Backwash
Chemical
Additives
Clarifiers
To Stream
Figure 3.14-VI WASTE WATER TREATMENT PLANT SCHEMATIC
PLANT H
149
-------
TSF-CT or
:.Halogen Tin
GSM & PORI
6 Floc-Clarifiers
Waste waters from blast furnace
recirc. blowdown, EOF recirc.
blowdown, slab mill, plate mill,
HS mill, et al., scale pit
effluents, boiler feed treat. &
boiler blowdown, contin. pickler
rinses, batch pickling dumps,
etc.
Lime and
Polyelectrolyte
Terminal
Lagoon
Oxygen Plant
Blowdown
Primary & Secondary
Sewage
Treatment Plant
Raw
Sewage
Spare
Lagoon
Sludge
(Sample 1-1)
To Stream
Figure 3.14-VII WASTE WATER TREATMENT PLANT SCHEMATIC - PLANT I
150
-------
Galvanizing
Mill
Cold Strip
Mill
Scrubber Water
Scrubber
Water
& Acid Rinse
Water
Reactor
(Liming)
Oily
Rinse Water
Primary
Settling
Steam Backwash
Conical
Filters
Thickener
To Stream
Sludge
(Sample J-l)
Storage
Tank
'Oil
Recovery
Figure 3.14-VIII WASTE WATER TREATMENT PLANT SCHEMATIC -
PLANT J
151
-------
Pickling
Hot Mills
HCL Regeneration
Oil Recovery
Detinning
Coal Washer
Sheet Mill
Etc.
Lagoon
Lagoon
To Stream
Sludge
(Sample K-2)
Plating
Contin. Anneal
Coating
D.M.
Cooling Water
Sewer
1 Lagoon I
Lime
Neut.
1 Lagoon I
Stream
Sludge (Sample K-l)
Figure 3.14-IX WASTE WATER TREATMENT PLANT SCHEMATICS
PLANT K
152
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3.15 SUBCATEGORY: MISCELLANEOUS OTHER OPERATIONS
Of the various operations covered in this section and listed in Table
3.15-1, only three produce any significant quantities of residues per
ton of product produced.
Table 3.15-1 MISCELLANEOUS FACILITIES ASSOCIATED
REGULARLY (OR OCCASIONALLY) WITH
I
IRON AND STEEL MILL OPERATIONS
Facility
Ore and raw material yards
Coal washing
Lime kilns
Direct reduction
Pig casting operations
Machine shops
Maintenance shops
Occurrence in Mill
Common
Rare
Rare
Rare (new technol.)
Common
Common
Common
But even these operations (coal washing, lime kilns and direct reduction)
are rare in steel mills. Therefore, the total quantities of residues
produced in the U.S. in iron and steel mills from these three operations,
compared with the quantities produced in the previous 14 subcategories,
is negligible.
However, with the expected increased use of direct reduction, in
combination with the new mini- and midi-steel mills, the quantities of
residues generated with the various direct reduction processes will
increase to significant levels in the next decade. The direct reduction
processes are aimed particularly towards the processing of low grade
ores with the more readily available non-coking coals . Presently,
less than 2% of the world's iron and steel is produced by direct
(2)
reduction
153
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In the direct reduction processes, both those using solid reducing
agents (coals or coke breeze) and gaseous reductants (natural or
snythetic gases), dusts and/or sludges are generated, depending on
product cooling method and the pollution control installation used.
None of the plants we had a chance to visit during our study had
direct reduction facilities and, therefore, no residues were collected
or analyzed.
The coal washing operations produce slimes, usually difficult to
settle and stabilize. Their disposal present problems but the
discussion of the disposal of these residues is not within the scope
of our study.
\
Dusts are collected in the lime kiln pollution control facilities, but,
again, they are not regarded as iron or steelmaking residues because
useful applications can be found within the steel mill (e.g., in acid
waste neutralization) or they are sold.
The ore and raw material yards including coal yards do not produce
residues.
The pig casting operations, when used, produce some dusts and process
waters with suspended solids (and "lime wash" residues used to prevent
sticking of iron to the molds). Again, the quantities of residues
generated are negligible and no samples were available from the mills
we visited.
The machine shops and maintenance shops produce wastes but with the
exception of their aqueous effluents (which are usually jointly treated
with other wastes in the waste water treatment systems and contribute
to those residues) no pollution control residues in any significant
quantities are generated in these operations.
154
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3.15 REFERENCES - MISCELLANEOUS OTHER OPERATIONS
1) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
2) Miller, J- R. Direct Reduction via Baden-Baden. I&SM, April 1976,
pp. 27-30.
155
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3.16 SUBCATEGORY: RECYCLING
The ideal solution to the problem of waste disposal, whether resulting
from process or pollution control, is an economically viable recycle
process whereby the waste can be effectively and efficiently reutilized.
The residues generated in the pollution control facilities of the
iron and steelmaking industry are no exception.
As was pointed out in Chapter II of this report and in previous
sections of this chapter, significant quantities of pollution control
residues are already recycled. In the U.S. close to 100% of the
residues from coking, sintering and coating operations are recycled:
80% from blast furnace departments, 65% from the rolling mills, and
about 50% from continuous casting operations. However, less than 25%
of the residues from the three steelmaking, pickling and waste water
treatment plant pollution control facilities are presently recycled
(Table 3.16-1). These figures are based on data obtained (1) during
our visits to the eleven steel plants, (2) from an extensive and
comprehensive review of the literature, and (3) from meetings and dis-
cussions with operating and environmental personnel in the U.S. steel
industry. Taking all of the information we were able to gather into
consideration, we would estimate that about 60% of all of the residues
generated in 1974 by pollution control operations in the mills was
recycled.
Most of the pollution control residues presently recycled are either
charged back directly into the blast furnace (e.g.,>5 mm mill scale)
or used as a feed in sintering or other types of agglomeration
operations. The finest dusts and sludges with particle sizes of ^ 50
microns are, in some cases, micro-pelletized before being used as sinter
feed. Smaller quantities of residues are also sold for various uses.
Table 3.16-2 indicates the percent recycled and sold, "stocked" and
dumped, based on the information supplied by thirteen U.S. steel mills
156
-------
Table 3.16-1 ESTIMATES OF IRON AND STEEL INDUSTRY POLLUTION CONTROL
RESIDUES IN THE U.S. IN 1974 AND COMPARISON OF % OF
RESIDUES RECYCLED IN THE U.S. AND ABROAD
Coking
Sintering
Blast furnace (iron)
Blast furnace (ferro
manganese)
BOF
OH
EAF
Vacuum degassing
Continuous casting
Rolling
Pickling
Coating f
Waste water treat.
Boilerhouse
TOTAL
(Reference:
Residue Arising in
U.S. (Million Tons)
1.0a (1.9-3.1b)
0.9
3.3
< 0.05
1.7
0.4
0.4
< 0.05
0.2
7.4
0.4
< 0.05
0.7
NA
— '16.5
% • Recycled or Sold in
U.S.
98
-^98"C
~*80
~33
—'25
< 20
<10
England
~100
-~iooc
50
NA
41
15
None
. Germany
/-'100
-^ 100°
85
NA
80
_ d
100e
Japan
-"100
^-100 C
~100
NA
^100
-
•~iooe
Recycled only as part of
other residues.
^50
~*65
<10
99+
<10
_g
^60
( 1)
NA
87
75
99+
30
-
65
(76)
NA
80
NA
99+
20
-
62
(64)
^100
-^100
NA
NA
NA
-
95h
(65)
a. Coke breeze (pollution control residues + coke dust).
b. Includes also coke pieces that passed the usually 1/2" screen.
c. Residues high in tramp elements are occasionally dumped or "stored."
d. No residue collected in 1974.
e. Recycled or "stored" for recycling.
f. Only coating and plating wastes.
g. By-product,not a residue; if throw-away sludge, no incentive to
recycle.
h. Based on information from 3 mills, each with j>10 million tons/year
capacity.
157
-------
Table 3.16-2 RELATIVE QUANTITIES OF RESIDUES RECYCLED,
SOLD, "STORED" AND DUMPED IN THE U.S.
(weight %)
Coking
Sintering
Blast furnace (iron)
BF (f erromanganese)
BOF
OH
EAF
Continuous casting
Rolling1*
Pickling
Coating
Waste water treatment
Recycled
or Sold
^-•98
*^98
77 A
(*^80)
xw30
NA
24.3
(25)
13
(15)
5.6
NA
50
70.4
(65)
<10
NA
^99
<10
NA
Main Routes
of Recycling
Sintering
£
Soaking pit
Other3
Sinter
Sinter
BOF feed
after
agglomer .
Sinter
Sinter +
other non-
mill0
BF feed
Sinter
BF feed
Sinter
Sinter +
other
(chem.)
Reprocessed
by
suppliers
Sinter
Stored
1-2
1-2
9.3
(10)
25.5
(30)
29
(35)
38.4
NA
25
20
(30)
20
NA
—
NA
NA
Dumped
<1
1-2
13.3
(10)
70
NA
50-2
(45)
58
(50)
56
NA
25
10
(5)
70
NA
<1
90
NA
a Processed by outside companies for non-iron or steelmaking purposes,
b Including scale and sludges.
c Minor quantities.
158
-------
cooperating in our study. The figures in parentheses are the "best
estimates,"in which information obtained from the literature and
various other sources were also taken into consideration, if different
from those which are based solely on data from our study.
There are five main reasons for dumping (and storing) and not recycling
the residues:
1) The fineness of the residues;
2) The difficulty in dewatering fine dust slurries and precipitates;
3) The high tramp element., especially zinc (Zn), lead (Pb), sulfur (S)
and alkalis (Na 0 + K 0),content of the residues;
4) The high oil content of some of the sludges and scales, and
5) The low metal (iron and/or non-ferrous) and carbon content of the
residues, or the low useful material (acid or oil) content.
When the metal and other valuable ingredient content of the residue or
waste is low, then recycling is usually not even considered.
To overcome the consistency or the difficulty in dewatering the residues,
dewatering and agglomeration methods are used before the recycling of
the residues, both in the U.S. and abroad. In dewatering the sludges,
various filtration (vacuum or pressure) approaches or centrifuging are
employed. For agglomeration, sintering is the most universally popular
approach. However, pelletizing or micro-pelletizing is also used,
sometimes in combination with sintering. Briquetting, while used in
some operations, has not yet gained significant acceptance as a method
for recycling steel mill residues.
(12)
Fine dusts are often wetted in pug mills or mixed with slurries
or sludges ' ' before disposal or recycling. After wetting the dusts
(2 22) (5) (20)
with the proper amount of waterv ' , steam , slurries^ ' or
(3 4)
sludges ' , the residues by themselves or in combination with raw
materials, including other residues , can be reused, usually after
conventional agglomeration, if the tramp content is low . Besides
159
-------
conventional sintering, briquetting and pelletizing are also
used for agglomeration. The raw materials added to the residues (and
other raw materials) can include binders and hardening agents such as
bentonite(8'9'12'21»22), basic hydroxides(10), slaked lime(11'21),
..*. , nj .,. v- «.- (10,13,14) (15,16,17)
modified lime-silica combinations , cement or
(18)
thermal plasticizing resins
To assure the proper composition of the residue raw material mixtures,
(19)
computers are also used
In another approach, the addition of fine residues to the coke-plant
(23)
feed is recommended as a means of recycling the residues. As a
result, the coke is enriched with 2% iron. The iron subsequently is
recovered during the burning of the coke in the ironmaking (BF)
operations.
Recycling of Zinc and Lead-Containing Residues
The afore-mentioned recycling procedures are and can be used, however,
only when the zinc (Zn), lead (Pb) and/or oil content of the residues
(24) (25)
are low or tolerable. In Germany, 0.1% to 0.2% Zn, in Japan
0;.25%v , while in the U.S. and England usually less than 0.4% Zn +
Pb-containing residues are recycled directly or through conventional
sintering after dilution with other raw materials.
While the fine consistency of the dusts and sludges and the difficulties
encountered in the dewatering of the slurries are no longer regarded as
serious problems in recycling of residues, the high tramp element and
oil contents are.
The "high" Zn and Pb content of the residues is regarded as the greatest
problem in the recycling of iron and especially steelmaking dusts and
sludges presently dumped or "stored." When the Zn and/or Pb-containing
wastes are recycled, these elements are reduced and volatilized.
Subsequently, the Zn and Pb vapors are oxidized and precipitated in the
160
-------
ducts of the sintering or blast furnace operations. In the blast
furnaces, in addition, when precipitated in the upper (cooler) parts
of the furnace this precipitation causies restrictions (e.g.,
"scaffolding") and difficulties in the operation of the furnace.
Zinc can also attack the refractory lining by reacting with alumina in
the lining and thereby causing additional damage to the furnace. The
contamination of the produced iron with Zn is also undesirable.
For the elimination of Zn and Pb and other interferences in the
recycling of residues, various approaches are used (Table 3.16-3).
Table 3.16-3 METHODS OF BENEFICIATION OF IRON AND
STEEL MILL ENVIRONMENTAL POLLUTION
CONTROL RESIDUES^
I. Physical separations
1. Gravity
2. Magnetic
3/ Froth Flotation
4. Skimming (of oil)
II. Pyrometallurgical methods
1. Rotary kiln processes: SL/RN,
Waelz, Krupp, Kawasaki
2. Other processes:
(a) Rotary hearth direct reduction
(b) Chloridization or chlorination
III. Hydrometallurgical methods
IV. Electrometallurgical methods
For the recovery of iron and elimination of Zn and Pb interferences,
thus far the physical separations, the hydrometallurgical methods
and electrometallurgical approaches were found to be practically not
feasible. However, several of the pyrometallurgical processes not only
161
-------
look promising(1'8'9'20'27'28'29'30) but are used successfully both in
pilot-type and in full-scale facilities, mainly outside of the U.S.,
. _ (9,31,32) . (33,34,35,36,37,38,39)
i.e., in Germany and in Japan »»>»>>
The oldest of these processes is the Waelz process. Originally
developed for the reduction of Zn-bearing ores, in the last several
years it has also been used for the recycling of Zn and Pb-containing
(9 32 40)
iron and steelmaking pollution control residues ' ' . Variations
of this process such as the Steel Company of Canada (STELCO)-Lurgi/
Republic Steel Corporation-National Steel Company (SL/RN)(31»35»38»41»
42,43,44) „ (45,46,47,48) . . _ . .(34,35,36,38)
' , Krupp , and the Kawasaki processes
are also used for the recycling of Zn and Pb-containing residues.
Further, other similar pyrometallurgical processes are still in the
, _ . (8,49,50,51,52,53,54,55)
experimental stage »»»»»>»'.
In a present variation of the Waelz process, 80,000 tons of zinc and
lead-containing residues are annually recycled in Duisburg-Wanheim
(Germany) by Berzelius Metalhutten GmbH, an associate company of
Lurgi<9'32>.
In other processes such as the previously mentioned SL/RN process, the
Xurgi-Nippon Kokan K.K. process, the Krupp and Kawasaki processes,
traveling grate pre-heaters are used to pre-indurate and pre-reduce
the residues before the rotary kilns to aid in the removal of Zn and Pb.
All of the above-mentioned processes, including the Waelz, as well as
the Vlnaty and the Ferro-Tech, Inc. , processes, are based on
the reduction by carbon. The Ferrocarb reduction process utilizes,
in addition to carbon, an hydrocarbon as the binder.
The Ferro-Tech process uses a rotating hearth furnace with four
zones, to which the "green" balls are fed in a thin layer. The four
zones are separated by baffles to achieve proper drying, pre-heating,
reducing and indurating at various temperatures and in various
162
-------
atmospheres. The Zn and Pb are volatilized In the reducing zone from
which the gases are handled separately through a baghouse for Zn and
Pb recovery.
In the Berzelius operation the properly sized and, if necessary,
dewatered residues are mixed with coke breeze (and/or coal dust) and
usually also with lime. The mixture, after pelletization, is
introduced into the rotary kiln. Additional coke dust or coal dust
is added to the kiln to supply additional heat and to keep the
atmosphere reducing. In the kiln the Zn and Pb are volatilized (after
reduction) during the induration (heat treatment) and subsequently
oxidized in the air to form the "Waelz dust" consisting of the oxides
of Zn and Pb and other dust particles generated during the process
(Table 3.16-4). After cooling, these dusts are recovered in
electrostatic precipitators. The end product from which 90-95% of
the Zn and Pb are removed,is also 90-95% reduced with respect to iron.
To avoid the oxidation of the "sponge iron" product in the air, it is
rapidly cooled. Screening is used to separate the fines from the
final product. Magnetic separation is used to recover additional iron
values, after which the reusable char (usually J^ 1 mm) is screened out
and recycled with the coke breeze or coal dust.
The Dravo-Vlnaty system uses a pre-heated inert material as a solid
(58)
heat carrier and a shaft furnace system for Zn and Pb removal
Obenchain Corporation also has developed a Zn and Pb removal
technology using a rotary
their CHOR pelletizing system
technology using a rotary kiln which is used in conjunction with
Dravo Corporation's in-house research and experience and this study
indicates that the selection of the recycling process for the residue
will depend on the tramp element content, the consistency and the
quantities of the various residues to be processed.
163
-------
Table 3.16-4 CHEMICAL COMPOSITION OF WAELZ OXIDES
(Percent by Weight - dry basis)
Sample
No.
1(27)
2(2?)
A(5?)
B<9>
Zn
64.9
51.4
40/
50
Pb
7.4
7.6
5/
10
Tot.
Fe
1.3
3.6
I/
5
C
2.9
12.0
i _
3
S
1.2
2.8
0.6/
0.8
CaO
0.4
0.6
NA
MgO
0.14
0.25
NA
Na2°
0.54
0.60
NA
K20
0.60
0.55
NA
Si02
0.4
1.5
NA
TiO +
A1203
0.15
1.0
NA
Zn + Pb>40%
-------
Several American steel corporations are studying the different
processes they could use in an economically and technically feasible
way to recycle their presently "stored" or dumped residues.
Recycling of Oily Residues
Another significant quantity of pollution control residues presently
dumped or "stored" originates in the rolling operations. While roughly
70% of the scale, including fine scale, is recycled or sold, most of the
sludges from the secondary and, in some cases, tertiary treatment
operations are dumped or "stored." According to our estimates of the
roughly 7.4 million tons of rolling residues, approximately 3.2 Mt were
still stored and dumped, mainly because of the high oil content
(especially "volatile" oil content). Due to the fine consistency of the
solids in (and the oil absorbing properties of) the sludges generated
in the post-scale pit water clarification operations, it is often
difficult to separate the oil from the iron-rich residues.
The oil content of the residues presents a two-fold problem in the
recycling of the rolling residues. When these oils are volatilized
during recycling (e.g., in pelletizing or sintering operations):
(1) they can cause fire in the electrostatic precipitators or
difficulties in baghouse operations, and (2) the escaping oil vapors
or their combustion products cause air pollution.
Most of the oil is easily removed from the rolling mill effluents by
various types of oil skimmers. The oil after separation is usually
recovered and reused. However, the oil cannot be separated from the
sludges by simple settling and skimming operations. As described in
Section 3.10, Rolling, various approaches are used for the separation
of oil from the aqueous phase and the residues.
In the successful operations, the oil is separated from the wastes
usually before the final sludge settling operations. Various chemical
treatments^59>6°'61\ including solvent extraction of the oils^ ' and
165
-------
/ ff) \
coalescers , and evaporation are used. However, when the oil is
not removed before the final settling of the residues, then the oils
have to be burned during the recycling (e.g., sintering or pelletizing)
and/or scrubbed out from the off-gases before they can reach the
dust control equipment and/or the atmosphere. This approach, however,
is still considered experimental
Recycling of Pickling Wastes
The recycling of pickling acid wastes or residues generated during the
neutralization of the waste acids and rinse waters presents a special
case. Today almost one-half million tons of residues are generated in
the U.S. (/4 million tons in acid neutralization and 0.1 million
tons in joint treatment facilities). Most of this pickling residue
is being dumped or "stored." However, the generation of these residues
can be eliminated if the hydrochloric acid is regenerated and the
sulfuric acid recovered, and commercially valuable by-products are
produced in place of residues.
The recovery of values from the hydrochloric acid and sulfuric acid
pickling liquors, besides economic considerations, is generally not
regarded as a problem because, among others, the Dravo, Lurgi, Ruthner,
etc., pickling waste regeneration and recovery processes are well
established and have been successfully used for many years.
In Europe (especially in Austria and Germany) and in Japan essentially
all waste pickling acids are reprocessed and the by-products (iron
oxide, iron sulfate, iron chloride) and the acids are either sold or
reused within the mills.
Occasionally when the purity of the iron oxides do not meet customer
specifications and, therefore, the residue cannot be sold, it is balled
and can be recycled through the furnace operations.-
166
-------
The sulfuric acid recovery ' * and hydrochloric acid
, (69,70,71,72,73)
regeneration processes have been used with success for
many years. However, the recycling of some mixed acids used in the
pickling ot surface treating of alloy and stainless steels is just
becoming more generally accepted.
A solvent extraction process was developed by Stora Kopparbergs in
Sweden for nitric-hydrofluoric acid mixtures. The process regenerates
both acids from the spent pickle liquor by recovering about 95% of
the nitric acid and 70% of the hydrofluoric acid^7 '75'*
167
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3.16 REFERENCES - RECYCLING
1) Pasztor, L. Problems of Resource Recovery In the Iron and Steel
Industry. In: Proceedings of the 4th Annual Industrial Pollution
Conference of WWEMA, Houston, Texas, March 30-April 1, 1976.
2) The Making, Shaping and Treating of Steel - Ninth Edition.
United States Steel Corporation, 1971.
3) van Cappelle, H. C. Handling of Recoverable Process Materials.
ISI Publication 53, Materials Handling in the Iron and Steel
Industry, 1973, pp. 37-46.
4) Krijgsman, M. Recovery and Utilization of Dust from the Basic
Oxygen Process. Blast Furnace Steel Plant, 1964, 52 (4),
Supplements 44, 46, 50, 54, 58, 62 and 108.
5) Pugh, J. L., and Fletcher, L. N. Experience in Handling and
Consuming Basic Oxygen Flue Dust in a Sinter Plant. In:
Proceedings of TMS.-AIME Ironmaking Conference, Chicago, 1972,
pp. 5.
6) Wass, E. A. Rotor-Plant Slurry Reuse. ISI Publication 128,
Management of Water in the Iron and Steel Industry, 1970, pp. 120-
123.
7) Byrns, H. A. Briquetting Fine Ores at Woodward, Alabama. In:
Proceedings of AIME Blast Furnace, Coke Oven and Raw Materials
Conference, 1949, 8, pp. 158-170.
8) Dressel, W. M., Barnard, P. G., and Fine, M. M. Pre-Reduced
Pellets from Iron and Steelmaking Wastes. AIME Annual Meeting
(Preprint 73-B-82), Chicago, 1973, pp. 12.
9) Serbent, H., and Maczek, H. Large-Scale Test for the Treatment
of BF and BOF Dust According to the Waelz Process. 34th
Ironmaking Conference, Toronto, 1975.
10) Anonymous. Waste Material Recycling Processes Promise Yield
Increases, Anti-Pollution Benefits. 33 Magazine, Metals
Production, September 1972, pp. 42-46.
11) Yartsev, M. A., and Molchanov, V. G. Recovery and Utilization of
Dust Precipitated from Off-Gases. Metallurgist/Metallurg., 1970
(12), pp. 789-791.
168
-------
3.16 REFERENCE (continued)
12) Goksel, M. A. Low Temperatures Agglomeration of Steel Plant
Solid By-Products for Reuse. In; Proceedings of 31st Annual
Mining Symposium and 43rd Annual Meeting, Minnesota Section of
AIME, 1971, pp. 103-110.
13) Mathias, W. M., and Goksel, M. A. Cold-Bonded Pellets Solid
Waste to Raw Material in Steel Mills. In: Ironmaking
Proceedings, Vol. 33, Atlantic City, 1974.
14) Mathias, W. M., and Goksel, M. A. Reuse of Steel Mill Solid
Wastes. Iron & Steel Engineering, December 1975, pp. 49-51.
15) Linder, R. K. Grangcold Pelletizing, State of the Art.
Skillings Mining Review, 1971 (18), pp. 1 and 6-9-
16) Granges Steel, The Grangcold Pelletizing Process. Granges Ore
News, October 1973, pp. 1-12.
17) George, H. D., and Boardman, E. B. The IMS-Grangcold Process
for Agglomerating Steel Mill Waste Material, Granges Ore News,
October 1973, pp. 13-21.
18) Shamada, S., et al. (Japan Steel Company, Ltd.). Method of
Turning Dust from Iron and Steel Manufacture into Pellets in
Water. Patent Sho 46-2736, January 23, 1971 (applic. 3-30-66).
19) Anonymous. Armco's $20 Million Answer to Mill Waste Recycling.
33 Magazine, May 1975, pp. 48-51.
20) Holley, C. A., and Weidner, T. H. New Process for Converting
Steelmaking Fumes into Low-Zinc Pellets. AISI Regional Meeting,
Chicago, 1969, pp. 1-8.
21) Italsider, S. P. A. A Method and Apparatus for Transforming
Iron-Containing Waste Slurries into Granular Solid Material.
British Patent 1,324,272, September 2, 1970 (applic. 9-69).
22) Barnard, P. G-, et al. Pre-Reduced Pellets from Iron and
Steelmaking Wastes. Paper of AIME Annual Meeting, Chicago, 1973,
pp. 12.
23) Kaiser Engineers. Consider Recycling Furnace Dust. Steel,
November 18, 1968 (163), pp. 70-72.
169
-------
3.16 REFERENCES (continued)
24) Tafel, V. Lehrbuch der Metallkunde. 2 Anf. Bd. 2 (Leipzig 1953).
25) Private communeiation. Verein Deutscher Eisenhuttenleute.
26) Private communication. The Japan Iron an4 Steel Federation.
27) Holowaty, M. D. A Process for Recycling of Zinc-Bearing
Steelmaking Dusts. AISI Regional Technical Meeting, Chicago,
1971, pp. 149-171.
28) Dressel, W. M., Barnard, P. G., and Fine, M. M. Removal of Lead
and Zinc and the Production of Pre-Reduced Pellets from Iron
and Steelmaking Wastes. U.S. Bureau of Mines RI-7927, 1974.
29) British Steel Corporation. The Arisings and Treatment of BSC
In-Plant Fines. Swinden Laboratories, Moorgate, Rotherham, 1975.
30) Anonymous. Recycling of Steel Plant Waste Materials.
Steel Research, British Steel Corporation, 1974.
31) Serbent, H., and Reuter, G. Development, Present Status and
Future Prospects of the SL/RN Process. Lurgi Report, Frankfurt/
Main, 1975.
32) Waelz Process, Reference Plants. Lurgi Chemie und Huttentechnik
GmbH, Frankfurt/Main, 1975.
33) Harada, Genzaburo, et al. U.S. Patent No. 3,146,088 - Kelji
Tsuhihata. Yawata Iron & Steel Company, Tokyo, 1961.
34) Kawasaki Process. Kawasaki Steel and Kawasaki Heavy Industries
Technical Brochure, 1971, pp. 11.
35) Hashimoto, H. On the Technology of Utilization of Dust from
Steelmaking. (Preprint, in Japanese) Realization of Resources
Technical Association, 1971, pp. 5.
36) Sakurai, S. Recycling of Oxide Fines in a Steel Plant. Presented
at IISI Symposium on Environmental Control in the Steel Industry,
Tokyo, February 18-22, 1974.
37) Saito, Yoshio. Direct Reduction Process for Recycling Steel Plant
Waste Fines. In:> Ironmaking Proceedings, Vol. 34, ISS, AIME,
Toronto, 1975.
170
-------
3.16 REFERENCES (continued)
38) Yatsunami, Kazuharu. Outline of SL/RN Reduced Pellet Plant at
Nippon Kokan's Fukuyama Works in Japan. Lurgi publication, 1975.
39) Private communication. Nippon Kokan K.K., Fukuyama, 1976.
40) Anonymous. Waelz Process, Reference Plants, Lurgi Bulletin,
Lurgi Chemie und Huttentechnik GmbH, Frankfurt/Main, 1975.
41) Yatsunami, K. Recycling Technology for Dusts Generated at Steel
Mills. (In Japanese) Kinzoku, 1974, 43 (10), pp. 18-22.
42) Tanaka, M., et al. The Properties of Reduced Pellets Made from
Basic Oxygen Furnace Dust. (Translation HB7-402, ex. Tetsu-to-
Hagane), 1967 (11), pp. 1166-1168.
43) Meyer, K., et al. The SL/RN Process for Production of Metallized
Burden. In; Proceedings of TSM-AIME Ironmaking Conference,
1965, pp. 23-27.
44) Thorn, G. G. W., and Schuldt, H. A. The Collection of OH Dust and
Its Reclamation Using the SL/RN Process. Canadian Mining &
Metallurgical Bulletin, October 1966, pp. 1229-1233.
45) Wetzel, R., and Meyer, G. Processing of Steel Works Dust and
Slurry. ISI Publication 139, Operation of Large BOF's, 1971,
pp. 44-51.
46) Meyer, G., and Bongers, U. The Krupp Direct Reduction Sponge
Iron Process. (Paper to Latin American Seminar on Direct
Reduction of Iron Ores), November 1973, pp. 9.
47) Bongers, U., and Wetzel, R. The Krupp Sponge Iron Process. In:
Proceedings of ISI Meeting on Alternative Routes to Steel, 1971,
pp. 55-58.
48) Meyer, G., and Wetzel, R. Experience with Direct Reduction at
Krupps. In: Proceedings of TSM-AIME Ironmaking Conference,(30) ,
1971, pp. 296-308.
49) Barnard, P. G., et al. Recycling of Steelmaking Dusts. In:
Proceedings of 3rd Mineral Waste Utilization Symposium, Chicago,
1972, pp. 63-68.
50) Barnard, P. G., et al. Recycling of Steelmaking Dusts. Technical
Report #52, U.S. Bureau of Mines, February 1972, pp. 14.
171
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3.16 REFERENCES (continued)
51) Dressel, W. M., et al. Removal of Lead and Zinc and the
Production of Pre-Reduced Pellets from Iron and Steelmaking
Wastes. U.S. Bureau of Mines NTIS Report PB-234-688/OWP,
July 1974 (20), Special Report.
52) Powell, H. E., Dressel, W. M., and Crosby, R. L. Experimental
Metals Reclamation Process Recovers Alloys from Steel Mill
Wastes. 33 Magazine, Vol. 13 (4), April 1975, pp.48-50.
53) Metallurgy Research Staff, U.S. Bureau of Mines. Reclaiming
and Recycling Secondary Metals. E/MJ, July 1975, pp. 94-98.
54) Highley, L. W., and Fukuhayashi, H. H. Method for Recovery of
Zinc and Lead from Electric Furnace Steelmaking Dusts. In:
Proceedings from 4th Mineral Waste Utilization Symposium, Chicago,
May 1975.
55) Powell, H. E., Dressel, W. M., and Crosby, R. L. Converting
Stainless Steel Furnace Flue Dust and Wastes to a Recyclable
Alloy. U.S. Bureau of Mines RI-8039, 1975.
56) U.S. Patent #3,850,613, November 26, 1974.
57) Dravo Corporation data.
58) Vlnaty, J. (Dravo Corporation). U.S. Patent #3,776,533, ^
December 4, 1973.
59) Leven, G. E., et al. Cleaning Water - Emulsion Effluent from
Cold Rolling Mills. Steel in the USSR 1 (10), 1971.
•
60) Schuldt, H. H., and Suffdetta, V. A. Recovery and Treatment of
Spent Steel Mill Solutions. Industrial Wastes, January/February
1975, pp. 20-23.
61) Vucich, M. G., and Vitellas, M. X. Emulsion Control and Oil
Recovery on Lubrication System of Double Reduction Mills.
(Paper presented at AISE Meeting, Cleveland, 1975.)
62) Practical Available Technology (PAT) Report. Steel Industry Sludge
is Being Reused. Environmental Science & Technology, Vol. 9,
July 1975, pp. 624-25.
172
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3.16 REFERENCES (continued)
63) Anonymous. Emulsionstrennung mit Unlaufverdampfen. Stahl und
Eisen, Vol. 95 (14), 1975, p. 661.
64) Private communication. Verein Deutscher Eisenhuttenleute.
65) Private communication. The Japan Iron and Steel Federation.
66) Reicher, Hans. Closed Loop Regeneration of Waste Pickle Liquor.
Iron and Steel Engineer, May 1974, pp. 47-49.
67) Dravo-Lurgi. Sulfuric Acid Recovery Systems. Dravo Corporation
Bulletin 74WWT03, Pittsburgh, Pa. 1974.
68) Seyler, J. K., et al. Sulfuric Acid and Ferrous Sulfate
Recovery from Waste Pickle Liquor. U.S. Environmental Protection
Agency EPA-660/2-73/032, Washington, D. C., January 1974.
69) Dravo-Lurgi. Hydrochloric Acid Regeneration Systems. Dravo
Corporation Bulletin 74WWTQ2, Pittsburgh, Pa., 1974.
70) Burteh, J. W. Hydrochloric Acid from Industrial Waste Streams -
The PORI Process. CIM Bulletin, January 1975, pp. 96-99.
71) Schuldt, A. A. Regeneration of Hydrochloric Acid Pickle Liquors
at Stelco's Hilton Works. CIM Bulletin, February 1974, pp. 82-88.
72) Conners, A. Hydrochloric Acid Regeneration as Applied to Steel
and Mineral Processing Industries. CIM Bulletin, February 1975,
pp. 75-81.
73) Rupay, G. H., and Jewell, C. J. The Regeneration of Hydrochloric
Acid from Waste Pickle Liquor Using Keram-Chemie/Lurgi Fluidized-
Bed Reactor System. CIM Bulletin, February 1975, pp. 89-93.
74) Muhlberg, Heinz, et al. The Pickling of Alloy Steels with the
Aid of a Regeneration Plant for Mixed Nitric and Sulfuric Acids.
Stahl und Eisen 95 (14), July 1975, pp. 639-642.
75) Dempster, J. H., and Bjoerklund, P. Operating Experience in
Recovery and Recycling of Nitric and Hydrofluoric Acids from
Waste Liquors. CIM Bulletin, February 1975, pp. 94-98.
173
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APPENDIX
METHODS USED IN ANALYZING STEEL INDUSTRY POLLUTION CONTROL RESIDUES
Initial Sample Preparation
Upon receipt, the samples were dried at 90 C until a constant residue
weight was obtained. Due to the widely varying water content of
similar samples, the lack of knowledge of specific sampling conditions,
and the partial dehydration of the samples during transport and storage,
the moisture content of the samples was not quantitatively determined.
The second step in the preparation for chemical analysis was the
removal of oil and grease from the samples by the Soxhlet extraction
*
method using Freon 113 as the extracting fluid. The Freon had been
previously purified by distillation. The residue recovered from the
Freon after the extraction was weighed and reported as oil and grease
content on a moisture-free basis. The de-oiled solids were used for all
subsequent analyses, the results of which were reported on a moisture-
free, greaseless, oil-less basis.
Chemical Analyses
Atomic absorption analyses were used for the determination of aluminum,
antimony, arsenic, calcium, chromium, lead, magnesium, manganese,
potassium, selenium, soidum, tin and zinc. The samples were dissolved
in mineral acids, and, if necessary, the residue was treated with
hydrofluoric acid and fused with sodium carbonate.
A separate sample was used for the sodium analysis. In the dissolution
of this sample for soidum analysis, any residue remaining after the
acid dissolution was treated with hydrofluoric acid, and then leached
with hydrochloric acid instead of fused with sodium carbonate.
* Registered Trade Mark of E. I. DuPont DeNemours & Company
174
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Standard atomic absorption analytical techniques were employed .
The samples were matched to the standards, and the most sensitive
absorption wavelengths were used in conjunction with the proper flame
type, either air acetylene or nitrous oxide acetylene. A deuterium
arc background corrector was used in the analyses of the lower
/2)
wavelength elements: arsenic, selenium, antimony and tin .
Gravimetric analyses was used for the determination of silica, carbon and
sulfur. Silica was determine by volatilization as silicon tetrafluoride
(3)
after dehydration by fuming perchloric acid . Carbon and sulfur
were determined by combusti9n in an oxygen stream, using a resistance
furnace as the h^at source. The carbon dioxide formed from the
combustion of the carbon was absorbed on an Ascarite bulb . On a
separate sample, the sulfur dioxide formed was absorbed and oxidized
in a hydrogen peroxide solution, then precipitated as barium sulfate .
The only volumetric technique employed was for the analysis of total
iron content. The samples were fused with a sodium peroxide - sodium
carbonate mixture in a zirconium crucible. After dissolution of the
melt and reduction of the iron, a standard cerate solution was used to
determine the iron content . When the manganese content was above 1!
the manganese was removed before the iron titration.
Cyanide determination in selected samples was performed by a cyanide
specific ion electrode method
Particle Size Analysis
The dried de-oiled samples were sieved through 10 ^, 20 ^ and 325 mesh
screens by two methods involving sonic vibrations. In one method, a
vibrating air column was used to do the sieving and in the other an
ultrasonic alcohol bath was used.
If the above screenings indicated that there was more than 20-30% of
+325 mesh material in a particular residue, another screening was
175
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performed. Here, another portion of the dried and de-oiled sample
was wet-screened through a 325 mesh screen and the +325 mesh fraction
dried and dry-screened using a Tyler Ro-Top (10 minutes) to ascertain
the quantity and sizing of the larger^-than-325-mesh particles.
This accounts for the dual screening figures given for some samples,
as indicated in the various tables throughout this report.
176
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APPENDIX REFERENCES
1) Perkin-Elmer Corporation. Analytical Methods for Atomic
Aborption Spectrophotometry. Norwalk, Conn., 1973.
2) Barnett, W. B., and Kerber, J. D. Atomic Absorption Newsletter
13, 3, 1974.
3) ASTM Method E247-67T. Silica in Iron Ores and Manganese Ores.
4) ASTM Method E30-68. Chemical Analysis of Steel, Cast Iron, Open
Hearth Iron and Wrought Iron.
5) Karchmer, J. T. The Analytical Chemistry of Sulfur and Its
Compounds. Interscience Publishers, New York, 1970-
6) Fischer, R. B., and Peters, D. G. Quantitative Chemical Analysis.
W. B. Saunders Company, Philadelphia, Pa., 1968.
7) Instruction Manual. Cyanide Electrode. Orion Research, Inc.
177
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-76-267
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
MANAGING AND DISPOSING OF RESIDUES FROM
ENVIRONMENTAL CONTROL FACILITIES IN THE
STEEL INDUSTRY
5. REPORT DATE
October 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Laszlo Pasztor and S.B. Floyd, Jr.
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Dravo Corporation
3600 Neville Road
Pittsburgh, Pennsylvania 15225
10. PROGRAM ELEMENT NO.
1BB-036; ROAP 21AZN-019
11. CONTRACT/GRANT NO.
Grant R803619
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711 ""•-,._
PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA-ORD
is. SUPPLEMENTARY NOTES JERL-RTP Project Officer tor this report is R.V. Hendriks, Mail
Drop 62, 919/549-8411 Ext 2557.
16. ABSTRACT
repOrt gives results of a, study of the management and disposal of resi-
dues from environmental control facilities in the steel industry. Information from 13
integrated U.S. steel mills is compared with that found in the literature and with data
collected during visits to English, German, and Japanese steel mills, technical and
industrial associations, and government agencies. Methods used to recycle dusts and
sludges and to regenerate or recover waste acids and oils are covered. Of the approx-
imately 16. 6 million tons of residues , 9. 1 million tons are recycled, and 7. 5 million
tons are dumped or stored for later reuse. The major reasons for not recycling the
residues , aside from economics , are higher than tolerable tramp element contents
(e.g. , Zn, Pb, Na, K) or oil content, and the extremely fine residue consistency.
The pollution control facilities used and the quantities and properties of the residues
generated in the various processes are described. In 1974, the U.S. steel industry
produced over 145 million net tons of raw steel. During the same period, over 16
million tons of pollution abatement residues were generated by the industry in 14 dif-
ferent iron and steelmaking subcategories , not including iron and steelmaking slags.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Air Pollution
[ron and Steel Industry
Residues
Dust
Sludge
Regeneration (Engineering)
A.ir Pollution Control
Stationary Sources
13B
11F
11G
07A
3. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport}
Unclassified
21. NO. OF PAGES
190
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
178
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