EPA-450/2-77-012^
CONTROL TECHNIQUES
FOR LEAD AIR EMISSIONS
VOLUME II:
CHAPTER 4 - APPENDIX B
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Office of Air Quality Planning and Standards
Emission Standards and Engineering Division
Research Triangle Park, North Carolina 27711
Telephone: (919) 541-5271
-------
EPA-450/2-77-012
CONTROL TECHNIQUES
FOR LEAD AIR EMISSIONS
VOLUME II:
CHAPTER 4 - APPENDIX B
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
December 1977
-------
NATIONAL AIR POLLUTION CONTROL TECHNIQUES ADVISORY COMMITTEE
Chairman and Executive Secretary
Mr. Don R. Goodwin, Director
Emission Standards and Engineering Division
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency-
Research Triangle Park, North Carolina 27711
Committee Members
Dr. Lucile F. Adamson
1344 Ingraham Street, N.W.
Washington, D.C. 20011
(Howard University-Professor,
School of Human Ecology)
Mr. O.B. Burns, Jr., Director
Corporate Environmental Activities
Westvaco Corporation
Westvaco Building, 299 Park Ave.
New York, New York 10017
Mr. Donald C. Francois, Asst. Dir.
Div. of Natural Resources Management
Dept. of Conservation and Cultural
Affairs
P.O. Box 578
St. Thomas, Virgin Islands 00801
Dr. Waldron H. Giles, Manager
Advanced Material and Space
Systems Engineering
General Electric Company
Re-entry and Environmental Systems Div.
3198 Chestnut St., Room 6839B
Philadelphia, Pennsylvania 19101
Mr. James K. Hambright, Dir.
Dept. of Environmental Resources
Bureau of Air Quality and Noise
Control
P.O. Box 2063
Harrisburg, Pennsylvania 17120
Mr. W.C. Holbrook, Manager
Environmental and Energy Affairs
B.F. Goodrich Chemical Co.
6100 Oak Tree Blvd.
Cleveland, Ohio 44131
Mr. Lee E. Jager, Chief
Air Pollution Control Div.
Michigan Dept. of Natural Resources
Stevens T. Mason Bldg. (8th floor)
Lansing, Michigan 48926
Dr. Joseph T. Ling, Vice Pres.
Environmental Engineering and
Pollution Control
3M Company
Minnesota Mining and Manufacturing Co.
Box 33331, Bldg. 42-5W
St. Paul, Minnesota 55133
Mr. Marcus R. McCraven
Asst. Vice Pres. of Environmental
Engineering
United Illuminating Co.
80 Temple St.
New Haven, Connecticut 06506
Mrs. Patricia F. McGuire
161 White Oak Dr.
Pittsburgh, Pennsylvania 15237
(Member of the Allegheny Co. Board
of Health, Pennsylvania)
Dr. William J. Moroz
Prof, of Mechanical Engineering
Center for Air Environment Studies
226 Chemical Engineering, Bldg. II
Pennsylvania State University
University Park, Pennsylvania 16802
Mr. Hugh Mullen, Director of
Government and Industry Relations
I.U. Conversion Systems, Inc.
3624 Market St.
Philadelphia, Pennsylvania 19104
111
-------
Mr. C. William Simmons
Air Pollution Control Officer
San Diego Air Pollution Control
District
9150 Cheasapeake Dr.
San Diego, California 92123
Mr. E. Bill Stewart, Dept. Dir.
Control and Prevention
Texas Air Control Board
8520 Shoal Creek Blvd.
Austin, Texas 78758
Mr. Victor H. Sussman, Dir.
Stationary Source Environmental
Control Office
Ford Motor Co.
Parklane Towers West, Suite 628
P.O. Box 54
Dearborn, Michigan 48126
IV
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TABLE OF CONTENTS
Page
SUMMARY xix
1.0 INTRODUCTION 1-1
2.0 BACKGROUND INFORMATION 2-1
2.1 Definitions 2-1
2.2 Origin and Use of Lead 2-4
2.3 Types of Lead Emissions 2-5
2.4 Sampling and Analytical Methods 2-9
2.5 Sources of Lead Emissions 2-10
2.6 Control Devices 2-12
2.7 Fugitive Lead Emissions 2-34
2.8 Control Costs 2-36
2.9 Emission Estimates and Emission Factors 2-42
2.10 Emission Trends and Projections 2-44
2.11 Anticipated Impacts 2-52
2.12 Emergency Episode Procedures 2-58
2.13 References 2-59
3.0 COMBUSTION SOURCES 3-1
3.1 Leaded Gasoline 3-1
3.2 Coal, Oil, Waste Oil, and Solid Waste 3-76
VI
-------
TABLE OF CONTENTS (continued) .
4.0 INDUSTRIAL PROCESS SOURCES 4"1
4.1 Lead Alkyl Manufacture 4~1
4.2 Storage Battery Manufacture 4-23
4.3 Primary Nonferrous Metals Production 4-38
4.4 Secondary Nonferrous Metals and Alloy 4-131
Production
4.5 Ferrous Metals and Alloy Production 4-173
4.6 Lead Oxides and Pigments 4-278
4.7 Pesticides 4-291
4.8 Lead Handling Operations 4-292
4.9 Miscellaneous Sources of Lead
APPENDIX A A-l
APPENDIX B B-l
VII
-------
LIST OF FIGURES
Page
2-1 Approximate Flow of Lead Through 2-8
U. S. Industry in 1975
2-2 Map of the Major Lead Emission Sources 2-13
2-3 Criteria for Selection of Gas Cleaning Devices 2-19
2-4 Fabric Filter with Mechanical Shaker 2-21
2-5 Envelope Type Fabric Filter with Automatic 2-21
Reverse-Air Cleaning Mechanism
2-6 Reverse-Jet Fabric Filter 2-22
2-7 Orifice Scrubber 2-26
2-8 Orifice Scrubber 2-27
2-9 Mechanical Scrubber 2-27
2-10 Mechanical-Centrifugal Scrubber 2-28
2-11 Centrifugal-Impingement Scrubber 2-31
2-12 Venturi Scrubber Design and Operation 2-32
2-13 Major Design Features of a Common ESP 2-35
2-14 Factors Influencing Capital and Annual Costs 2-39
of Operating Air Pollution Control System
3-1 Octane Number Versus Lead Content for Gasolines 3-9
3-2 Yearly Trends of United States Passenger Car 3-14
Engine Design and Gasoline Quality
3-3 Historical Source of Octane Quality Commercial 3-15
Gasolines
3-4 Percent of Model Year Cars and of all Cars on 3-17
the Road for Which Premium Gasoline is
Recommended, and Percent Premium Sales,
1965-1976
3-5 United States Gasoline Demand - 1960-1975 3-18
3-6 Vapor Pressure of Lead Compounds 3-32
Vlll
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LIST OF FIGURES (continued)
Page.
3-7 Predicted Reduction in Lead Use in Gasoline 3-40
From Estimated 1974 Level Based on Federal Fuel
Additive Regulations and Gasoline Use Increases
of 0 and 5 Percent Per Year
3-8 Projected Lead Reduction from 1974 Level _ 3-42
Resulting From the Use of Nonleaded Fuel in
1975 and Later Model Year Automobiles. Curves
C-D are for Resumption of Use of Leaded Fuel at
1974 Concentration for all 1980 and Later Model
Years
3-9 DuPont Muffler Lead Trap 3-48
3-10 Ethyl Corporation Tangential Anchored Vortex 3-50
Traps Construction Features
3-11 PPG Particulate Lead Trapping System Features 3-52
3-12 Spreader and Vibrating Grate Stokers 3-78
3-13 Pulverized-Coal Unit 3-79
3-14 Diagram of Coal-Fired Boiler Equipped with 3-86
an ESP
3-15 Total Capital and Annualized Costs for ESP's 3-89
on Coal-Fired Boilers
3-16 An Oil Front-Fired Power Plant Steam Generator 3-93
3-17 ESP Installation of a Municipal Incinerator 3-99
Showing Gas Conditioning System
3-18 Capital Costs for Various Types of Control 3-109
Devices for Municipal Incinerators
3-19 Annualized Costs for Various Control Devices 3-110
on Municipal Incinerators
4-1 Sodium-Lead Alloy Process for the Production 4-3
of Tetraethyl^Lead
4-2 Typical Lead Reverberatory Furnace Used 4-7
in Lead Additive Manufacturing
IX
-------
LIST OF FIGURES (continued)
Page
4-3 Electrolytic Process for Tetramethyl Lead 4-12
Production
4-4 Flow Diagram of Lead Acid Battery Plant 4-24
4-5 Average Controlled Lead Emissions From Tested 4-33
Facilities
4-6 A Typical Ore Mining and Processing Operation 4-41
4-7 Flow Diagram of Primary Lead Smelter 4-45
4-8 Lead Updraft Sintering Machine 4-46
4-9 Lead Blast Furnace 4-49
4-10 Process Flow Diagram For Primary Lead Smelting 4-57
Showing Potential Industrial Process Fugitive
Particulate Emission Points
4-11 Sulfuric Acid Plant Installed on a Primary 4-60
Lead Smelter
4-12 Flow Diagram of Primary Zinc Production 4-73
4-13 Downdraft Sinter Machine 4-76
4-14 Horizontal Retort 4-76
4-15 Vertical Retort 4-80
4-16 Process Flow Diagram For Primary Zinc 4-84
Production Showing Potential Industrial
Process Fugitive Emission Points
4-17 Primary Copper Smelter Flow Diagram 4-96
4-18 Multiple-Hearth Roaster 4-98
4-19 Fluid-Bed Roaster 4-99
4-20 Reverberatory Furnace 4-103
4-21 Electric Smelting Furnace 4-104
4-22 Copper Converter 4-108
-------
LIST OF FIGURES (continued)
Page
4-23 Process Flow Diagram for Primary Copper
Smelting Showing Potential Industrial
Process Fugitive Emission Points
A 1 T O
4-24 Blast Furnace With Typical Air Pollution
Control System
4-25 Reverberatory Furnace with a Typical Emission 4-133
Control System
4-26 Pot Furnaces with Typical Emission Control 4-134
System
4-27 Process Flow Diagram for Secondary Lead 4-138
Smelting Showing Potential Industrial Process
Fugitive Particulate Emission Points
4-28 Process Flow Sketch of Brass/Bronze 4-152
Reverberatory Furnace
4-29 Brass Reverberatory Furnace 4-154
4-30 Gas-Fired Rotary Brass Melting Furnace 4-155
4-31 Process Flow Diagram for Secondary Brass and 4-161
Bronze (Copper Alloy) Production Showing
Potential Industrial Process Fugitive
Particulate Emission Points
4-32 Production Flow Diagram for a Typical Gray 4-174
Iron Foundry
4-33 Cross-Section of a Cupola Furnace for Gray 4-175
Iron Production
4-34 Process Flow Diagram for Foundries Showing 4-184
Potential Industrial Process Fugitive
Particulate Emission Points
4-35 Method of Capturing Exhaust Gases From Cupola 4-189
Operations
4-36 Fabric Filter Control System on a Gray Iron 4-190
Cupola
4-37 Particulate Emissions as a Function of Venturi 4-195
Orifice Pressure Drop
XI
-------
LIST OF FIGURES (continued)
Page
4-38 Venturi Gas Scrubbing System Installed on a 4-196
Foundry Cupola
4-39 Flow Diagram Depicting the Principal Units and 4-203
Auxiliaries in Modern Blast-Furnace Plant
4-40 Idealized Cross-Section of a Typical Modern 4-205
Blast-Furnace Plant
4-41 Diagram which Illustrates the Principal Parts 4-207
of an Open-Hearth Furnace
4-42 Diagrammatic Section Along the Length of a 4-208
Liquid-Fuel Fired Open-Hearth Furnace
4-43 Schematic Elevation Showing the Principal 4-210
Operating Units of the Basic Oxygen Process
Steelmaking Shop
4-44 Schematic Cross-Section of a Heroult Electric 4-212
Arc Furnace
4-45 Process Flow Diagram for Iron Production 4-222
Showing Potential Industrial Process Fugitive
Particulate Emission Points
4-46 Ferroalloy Production Flow Diagram 4-256
4-47 Submerged-Arc Furnace for Ferroalloy Production 4-257
4-48 Ball Mill Process for Lead Oxide Manufacture 4-280
4-49 Barton Pot Process for Lead Oxide Manufacture 4-280
4-50 Flow Diagram for Type Metal Processes 4-293
4-51 Cross-Section of a Hydraulic Extrusion Press 4-300
4-52 Screw-Type Extrusion Press 4-300
4-53 Sources of Particulate Emissions in Cement 4-307
Plant
4-54 A Typical Rotary Cement Kiln and Clinker 4-308
Cooling System with Fabric Filter
4-55 Regenerative Glass Furnace 4-318
B-l Control system diagram for brass and bronze B-ll
Reverberatory Furnace
XII
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LIST OF TABLES
Page
1 National Atmospheric Lead Emissions in 1975 *x
2 Lead Control Techniques xxv
3 Performance of Lead Emission Controls xxvi
2-1 Origins of Lead in United States 2-6
2-2 United States Consumption of Lead By Industry 2-7
2-3 Composition - Lead Air Emissions 2-11
2-4 Lead Particulate Size Distribution 2-14
2-5 Lead Control Techniques and Performances 2-15
2-6 Comparative Control Efficiencies for Lead 2-16
and Total Particulate
2-7 Fugitive Lead Emissions 2-37
2-8 Lead Emission Factors, Annual Emissions, and 2-45
Control Techniques
2-9 Relative Contribution of Lead Emissions From 2-50
All Sources
3-1 Operating Conditions for Determining Octane 3-2
Numbers of Fuels
3-2 ASTM Rating Scale for Automotive Fuels Above 3-10
100 Octane
3-3 Lead Consumption in U.S. Manufacture of 3-19
Lead Alkyl Gasoline Additives
3-4 Lead Particle Size Distribution From Vehicles 3-24
With Conventional Mufflers
3-5 Distribution of Particle Sizes in Exhaust at 3-25
260°F From Leaded and Unleaded Fuel
3-6 Lead Particle Size Distributions for Three 3-28
Production Vehicles
3-7 Melting Points of Selected Lead Compounds 3-33
3-8 Composition of Lead Deposits From A Lead Trap 3-34
Xlll
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LIST OF TABLES (continued)
Page
3-38
3-45
3-60
3-9 Amended Fuel Additive Regulations as of
September 28, 1976
3-10 Comparison of Properties of CNG, LNG, and
Gasoline
3-11 Estimated Sales-Weighted Fuel Economy For
American-Made Automobiles
3-12 Estimated Costs of DuPont Production Prototype 3-65
Lead Traps
3-13 Estimated Costs for Ethyl Tangential Anchored 3-67
Vortex Trap Based on 57.0 Mm (36,000-mi) Muffler
Life, 1973
3-14 Characteristics of Uncontrolled Exhaust Gas 3-81
From Pulverized-Coal-Fired Utility Boiler
3-15 Characteristics of Uncontrolled Exhaust Gas 3-82
From Cyclone Coal-Fired Boiler
3-16 Example Flue Gas and Precipitator Collection 3-87
Efficiency Data
3-17 Characteristics of Uncontrolled Exhaust Gas 3-95
From Oil-Fired Boilers
3-18 Characteristics of Uncontrolled Exhaust Gas 3-101
From Municipal Incinerators
3-19 Design Parameters for Electrostatic 3-105
Precipitators on Incinerators
3-20 Characteristics of Uncontrolled Exhaust Gas 3-116
From Medium and Large Waste Oil-Fired Boilers
4-1 Typical Exhaust Parameters for Battery 4-29
Manufacturing Operations
4-2 Lead Control-Techniques and Associated Costs 4-32
for Lead-Acid Battery Plants
4-3 Lead Removal Efficiency for Well-Controlled 4-34
Processes
XIV
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LIST OF TABLES (continued)
Page
4-4 Lead Emissions from Ore Grinding and Crushing 4-39
Operations
4-5 Characteristics of Uncontrolled Exhaust Gas 4-48
from Lead Sinter Machine
4-6 Characteristics of Uncontrolled, Undiluted 4-51
Exhaust Gas From a Lead Blast Furnace
4-7 Characteritics of Uncontrolled Exhaust Gas 4-54
From a Lead Dross Reverberatory
4-8 Estimates of Fugitive Dust Emissions From 4-55
Operations at one Primary Lead Smelter
4-8a Estimates of Fugitive Dust Emissions From 4-56
Operations at Two Primary Lead Smelters
4-9 Particle Size Distribution of Flue Dust from 4-58
Updraft Primary Lead Sintering Machine
4-10 Performance of Blast Furnace and Dross 4-66
Reverberatory Furnace Baghouse
4-11 Characteristics of Uncontrolled Exhaust Gas 4-77
From a Zinc Sinter Machine
4-12 Lead Emissions at Zinc Sinter Machines 4-78
4-13 Characteristics of Uncontrolled Exhaust Gas 4-81
From Horizontal Zinc Retorts
4-14 Characteristics of Uncontrolled Exhaust Gas 4-83
From A Vertical Zinc Retort
4-15 Lead Emissions - Zinc Retorts 4-85
4-16 Fugitive Lead Emission Sources and Estimated 4-86
Uncontrolled Particulate Emission Factors
4-17 Characteristics of Uncontrolled Exhaust Gas 4-101
From A Copper'Roaster
4-18 Characteristics of Uncontrolled Exhaust Gas 4-106
From a Copper Reverberatory Furnace
4-19 Characteristics of Uncontrolled Exhaust Gas 4-110
From a Copper Converter
xv
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LIST OF TABLES (continued)
Page
4-20 Uncontrolled Fugitive Emissions From Copper 4-112
Smelting Operations
4-21 Chemical Characteristics of Fugitive 4-114
Particulate Emissions From Various Process
Steps in Primary Copper Smelting
4-22 ESP Performance on Copper Reverberatory 4-118
Furnace and Roaster Combined Exhaust Gas Streams
4-23 ESP Performance on Two Copper Converter 4-119
Operations
4-24 Characteristics of Uncontrolled Exhaust Gas 4-136
for Secondary Lead Blast Furnace
4-25 Uncontrolled Exhaust Gas Characteristics for 4-137
Secondary Lead Reverberatory Furnace
4-26 Secondary Lead Fugitive Dust Sources and 4-137
Emissions
4-27 Performance of a Fabric Filter on a Secondary 4-143
Lead Reverberatory Furnace
4-28 Particulate Emissions From Brass and Bronze 4-158
Ingot Production
4-29 Characteristics of Uncontrolled Exhaust Gas 4-159
From A Brass and Bronze Reverberatory Furnace
4-30 Lead Emissions From Brass and Bronze 4-163
Production in 1974
4-31 Particulate Emissions From a Brass and Bronze 4-165
Reverberatory Furnace
4-32 Characteristics of Typical Exhaust Gas From 4-181
Gray Iron Melting Furnaces
4-33 Lead Emission Factors and Annual Lead Emissions 4-183
for the Gray Iron Foundry Industry
4-34 Emission Characteristics for Various Foundry 4-186
Operations
XVI
-------
LIST OF TABLES (continued)
Page
4-35 Dust and Fume Emissions From Gray Iron Cupolas 4-187
4-36 Fabric Filter Performance Test Results on a 4-192
Gray Iron Electric Arc Furnace
4-37 Production for Iron and Steel Industry in 1975 4-200
4-38 Characteristics of Uncontrolled Exhaust Gas 4-214
From Sintering Machines
4-39 Characteristics of Uncontrolled Exhaust Gas 4-217
From Iron Blast Furnaces
4-40 Characteristics of Uncontrolled Exhaust Gas 4-219
From Open-Hearth Steel Furnaces
4-41 Characteristics of Uncontrolled Exhaust Gas 4-224
From Basic Oxygen Furnaces
4-42 Characteristics of Uncontrolled Exhaust Gas 4-225
From Electric Arc Furnaces
4-43 Summary of Performance Test Results on a 4-229
Fabric Filter Serving Sinter Plant
4-44 Performance of an Electrostatic Precipitator 4-234
Serving an Open-Hearth Furnace
4-45 Summary of Performance Test Results on a 4-235
Venturi Scrubbing System Serving a Basic
Oxygen Furnace
4-46 Performance of Fabric Filter Serving an 4-238
Electric-Arc Furnace
4-47 U. S. Ferroalloy Production in 1975 4-254
4-48 Characteristics of Exhaust Gas From Open 4-261
Electric Furnaces Processing Common Ferroalloys
4-49 Lead Emissions From Ferroalloy Production 4-266
4-50 Test Results on an Electric Arc Furnace 4-269
Equipped With Fabric Filter
xv 11
-------
LIST OF TABLES (continued)
Page
4-51 Characteristics of Uncontrolled Exhaust Gas 4-284
From Lead Oxide Ball Mill and Barton Pot
Processes
4-52 Performance Test Results on Fabric Filter 4-287
Systems
4-53 Characteristics of Uncontrolled Exhaust Gas 4-311
From Portland Cement Kiln
A-l Prefixes for the SI System of Measurement A-2
A-2 Conversion Factors A-4
B-l Steps To Determine Total Equipment Costs B-2
B-2 Capital Cost Bases B-3
B-3 Annualized Cost Bases B-4
B-4 Retrofit Factors B-5
B-5 Characteristics of Uncontrolled Exhaust Gas B-10
From a Brass and Bronze Reverberatory Furnace
B-6 Determination of Capital Costs for Particulate B-12
Control System for a Brass and Bronze
Reverberatory Furnace
B-7 Control System Annual Operating Cost B-13
xvin
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SUMMARY
This report documents atmospheric emissions of lead
(Pb) and its compounds from various sources, methods for
controlling these emissions, and approximate costs for
implementing these control methods. Estimates of energy
and environmental impacts are given for specific model
plants.
Lead and its compounds enter the atmosphere from com-
bustion of fuels, especially leaded gasoline, and from
industrial activities. Rural ambient air levels are
commonly below 0.5 yg/m whereas urban air lead levels are
mainly 1 to 2 yg/m . In highly populated areas daily
averages may exceed 3 to 5 yg/m and in dense traffic, lead
levels have been known to exceed 20 yg/m for several hours,
Near large stationary sources, levels have exceeded 300
yg/m .
In 1975, atmospheric emissions of lead in the United
States amounted to 141 Gg (155,900 tons),* of which 90.4
percent was contributed by gasoline combustion. These
emissions are summarized by source in Table 1.
*
The Appendix presents common conversion factors for
International and English systems of measurements.
xix
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Table 1. NATIONAL ATMOSPHERIC LEAD EMISSIONS IN 1975
Gasoline combustion
Coal combustion
Oil combustion
Solid waste incineration
Waste oil disposal
Lead alkyl production
Storage battery production
Ore crushing and grinding
Primary lead smelting
Primary copper smelting
Primary zinc smelting
Secondary lead smelting
Brass and bronze production
Gray iron production
Ferroalloy production
Iron and steel production
Lead oxide production
Pigment production
Cable covering
Can soldering
Type metal
Metallic lead products
Cement production
Lead glass production
Total
Megagrams
127,800
228
100
1,170
5,000
1,000
82
493
400
1,314
112
750
47
1,080
30
605
100
12
113
63
435
^T *J ^
77
312
56
141,380
Tons
140,900
257
110
1,296
5,480
1,100
90
544
440
1,444
124
830
52
1 192
.4. £ ^ X ^-
33
667
110
JL J» \J
13
-L J
1 2^
- i- „
70
/ \j
/.Qft
'fOU
Q C
O J
OA /.
J4-H
62
155,880
xx
-------
SOURCES OF LEAD AIR EMISSIONS
Lead emission sources can be categorized into three
groups: 1) combustion sources, which emit lead by volatilization
of lead components contained in the fuel or in refuse; 2)
metallurgical sources, which generate lead emissions by
volatilization or mechanical action from melting and processing
of metallic ores and materials; and 3) manufacturing sources,
which generate lead emissions by using refined lead as the
raw material to produce a lead-containing product. All
sources listed in Table 1 are considered in this study.
The nature of lead emissions depends on their origin
and on the mechanism of formation. High-temperature combustion
and smelting processes generate submicron particulate lead
fumes. Lead emissions from material handling and mechanical
attrition, as in battery manufacturing, consist of larger-
sized dust particles. The main chemical forms of lead
emissions include elemental lead (Pb), oxides of lead (PbO,
Pb02, Pb20.,, etc.), lead sulfates and sulfides (PbSO^,
PbS, etc.), alkyl lead (PI 3H3)4> Pb(C2H5)4), and lead
halides.
EMISSION FACTORS
Emission factors for lead were developed for each
source category; they are based on source tests, particulate
chemical analyses in the literature, industry responses,
XXI
-------
material balances, and engineering judgment. Because data in
the literature are limited, most of the emission factors
should be regarded as approximations; they do provide guide-
lines for estimating emissions from large groups of sources.
In many processes, lead emissions are a function of the lead
content of the charge or raw materials, for which data are
highly variable and sparse. In addition, the efficiency of
common particulate control devices with respect to lead
particulates is not well documented.
NATIONAL EMISSION INVENTORY
Annual emissions from each source category are determined
by use of (1) the uncontrolled emission factor, (2) the 1975
production output or consumption, and (3) an overall average
emission control factor for each source. Production and
consumption rates are fairly reliable. Emission factors and
overall control efficiency values are inherently less accurate
because of the limited availability of source-specific data.
The overall collection efficiencies for lead are assumed
equivalent to those for collection of nonlead particulates.
This assumption has been verified by limited EPA source tests
2
on fabric filters. For ESP's and wet scrubbers, some recent
information indicates differences in the collection efficiency
S fi 7 ft
between particulates and lead. ' ' ' Lead compounds are
probably less efficiently removed by ESP and wet scrubbers
whenever lead emissions are concentrated in the very fine
particulate sizes.
xxi i
-------
EMISSION TRENDS AND PROJECTIONS
Lead emissions from combustion of gasoline can be expected
to decrease by about 65 percent by 1985 as levels of lead in
gasoline are reduced from the current 0.45 g/litre (1.7 g/gal)
to 0.13 g/litre (0.5 g/gal) and as sales increase at 2 percent
per annum. These factors represent a reduction of 58 percent
of total 1975 lead emissions. They will also result in
reduction of lead emissions from waste oil combustion because
of a proportionate reduction in lead content, from lead alkyl
manufacturing because of reduced production plans. Federal
new source performance standards for particulate will also
strongly influence future lead emissions. Following are esti-
mates of 1985 lead emissions: gasoline combustion 44.9 Gg
(49,500 tons); stationary combustion sources, 3.7 Gg (4038
tons); and industrial processes, 4.2 Gg (4650 tons). These
values total 52.8 Gg (58,200 tons) of lead emissions, a reduc-
tion of about 63 percent from 1975 emissions.
CONTROL TECHNIQUES
Emissions of lead particulates from automotive sources
can be reduced by installing control devices, by reducing
or eliminating the lead content of gasoline, or by a combina-
tion of these methods. The Federal law requires the reduction
of the average lead content in gasoline from 0.45 g Pb/litre
(1.7 g Pb/gal) to 0.13 g Pb/litre (0.5 g Pb/gal) by 1979 which
should reduce gasoline lead emissions substantially.
XXlll
-------
Application of particulate traps on automotive exhaust systems
is under investigation and is discussed in detail in this
document. However, there are no traps installed commercially
at this time.
For stationary source emissions, the use of high-efficieny,
fine particulate controls such as electrostatic precipitators
(ESP), fabric filters, and wet scrubbers is reviewed. Few
processes incorporate control devices specifically for lead
control. Rather, these devices are installed for collection
of particulate to comply with state or federal regulations
and/or to recover valuable product. Control techniques
described herein are not, therefore, intended exclusively for
lead control, but do offer potential for reducing lead emissions,
Table 2 shows the lead control techniques that are available
or that are used by the various lead emission sources.
Selection of a control strategy must be based upon the
required efficiency, gas stream characteristics, particle
characteristics, space restrictions, and many other site-
specific, economic, and technical factors. Also, the lead
emissions and the effects of lead pollution can be reduced by
relocation or shutdown of sources, fuel substitution, process
changes, improvement of operating practices, and atmosphere
dispersion techniques. Table 3 shows the possible lead
emission reductions with the various control techniques
available.
COST OF CONTROL
The incremental costs to the consumer of nonlead motor
xxiv
-------
vehicle fuels are difficult to assess because they involve
extremely complex technical and political factors.
TABLE 2
LEAD CONTROL TECHNIQUES
Controlled Source
Principal Method of Control
Gasoline combustion
Waste oil disposal
Metallurgical processes
Lead alkyl manufacture
Combustion and incineration
Industrial processes
Reduce Pb in gasoline.
Pretreat before burning
Blend with fuel oil
Reduce Pb in gasoline
Fabric filters, ESP
Scrubbers, fabric filters
ESP
Fabric filters, scrubbers
xxv
-------
TABLE 3
PERFORMANCE OF LEAD EMISSION CONTROLS
Control Device
Possible Emission Reduction
•fc
Lead particulate
traps-autos
Fabric filters
Scrubbers
ESP
Cyclone collectors
-907.
95-99.99%
80-997o
95-99.7%
-857o
Assuming that lead particulates are captured with
the same control efficiency as for total particulates.
XXVI
-------
Results of some cost studies (Section 3.1.3) indicate that the
incremental consumer cost of controlling lead emissions by
requiring the use of nonleaded gasoline ranges from 1 to 4
cents per gallon.
Incremental costs for various types of particulate and
lead collection devices range from about $5 to $20 per new
automobile, depending upon the type of device. Retrofit
installations will cost considerably more.
The capital and annualized costs of particulate emission
control are given for each industrial process and control
alternative. These data are based on actual operations or
engineering cost analyses and are escalated to reflect mid-
1976 costs. These costs generally reflect the cost of com-
pliance with existing regulations for particulate emissions.
Costs attributable to control of lead emissions are not pro-
vided, since they would depend on the degree of control
required at a specific site, and it is generally impossible to
allocate lead control costs from costs for total particulate
control.
IMPACTS OF CONTROLS
The environmental and energy impacts of meeting an air
quality standard for lead are thought to be negligible.
Relatively few plants may be affected by such a standard. The
additional wastewater and solid wastes generated above that
generated by SIP controls will be insignificant. The energy
xxvi i
-------
impact may be significant at plants which utilize wet scrubbers
or which require additional control equipment. In this docu-
ment, order of magnitude estimates are given for particulate
SIP control impacts for major sources of lead. Generally,
impacts for lead control will be much less than for particu-
late control.
XXVlll
-------
REFERENCES
1. Scientific and Technical Assessment Report. Office
of Research and Development. U. S. Environmental
Protection Agency. Washington, D. C. EPA 600/6-
75-OOX. STAR series. February 1975.
2. Preferred Standards Path Analysis on Lead Emissions
from Stationary Sources. Emission Standards and
Engineering Division. U. S. Environmental Protection
Agency. Research Triangle Park, N. C. September 4,
1974.
3. Environmental Protection Agency Regulations of Fuels
and Fuel Additives. 40 CFR 42675. Part 80. Subpart
B. Sec. 80.20 (a) (1). September 28, 1976.
4. Control Techniques for Particulate Air Pollutants.
AP-51. U. S. Environmental Protection Agency. Office
of Air Programs. Research Triangle Park, N. C. January
1969. 215 p.
5. KaaKinen, J. W., R. W. Jordan, M. H. Lawasani, and
R. E. West. Trace Elements Behavior in Coal-Fired
Power Plants. Environmental Science and Technology.
Volume IX (9): 862-869. September 1975.
6. Lee Jr., R. E., H. L. Crist, A. E. Riley, and K. E.
MacLeod. Concentration and Size of Trace Metal Emissions
from a Power Plant, a Steel Plant, and a Cotton Gin.
Environmental Science and Technology. Volume IX (7):
643-647. July 1975.
7. Klein, D. H. et al. Pathways of Thirty-Seven Trace
Elements Through Coal-Fired Power Plant. Environmental
Science and Technology. Volume IX (10): 973-979.
October 1975.
8. Natusch, D. F. S. and C. A. Evans, Jr. Toxic Trace
Elements: Preferential Concentration in Respirable
Particles. Science. Volume 183: 202-204. January
1975.
XXIX
-------
4.0 INDUSTRIAL PROCESS SOURCES
Industrial processes contributed an estimated 7.1
Gg (7,800 tons) or 5.0 percent of the total nationwide
atmospheric lead emissions in 1975. The major source
categories include production of lead alkyl and storage
batteries, primary and secondary nonferrous metals, ferrous
metals and alloys, and lead oxide, and also lead handling
operations and miscellaneous sources.
4.1 LEAD ALKYL MANUFACTURE
Alkyl lead compounds, tetraethyl lead (TEL) and
tetramethyl lead (TML), are used as antiknock gasoline
additives. Additive production in 1975 was 296 Gg
(326,000 tons), approximately 72 percent of the industrial
capacity, accounting for the consumption of 190 Gg of
refined lead (207,000 tons). There are six plants in the
2
United States, owned by four companies. The 1975 lead
emissions from the lead alkyl industry were estimated at
1000 Mg (1,100 tons).3
Commercially, TEL and TML are produced either by
alkylation of sodium-lead alloy or by electrolysis of an
alkyl Grignard reagent. TEL accounted for over 75 percent
4-1
-------
of the additive production in 1973. More than 90 percent of
4
the TEL is made by the sodium-lead alloy process.
3
4.1.1 Sodium-Lead Alloy Process
Figure 4-1 is a simplified process flow diagram for the
batch manufacturing of TEL. The basic step in this process
is the reaction of sodium-lead alloy with an excess of ethyl
chloride in the presence of acetone catalyst. The reaction
takes place in autoclaves at 70 to 75°C (158 to 167°F) and
a pressure of 350 to 419 kPa (50 to 60 psi) as follows:
4 NaPb + 4 C2H5C1 -> (C2H5)4 Pb + 4 NaCl + 3 Pb
Production of TML by the sodium-lead alloy process is
similar, except that methyl chloride is used instead of
ethyl chloride. To increase the reactivity of sodium-lead
alloy and methyl chloride, the reaction is carried out in
the presence of a catalyst such as aluminum chloride and
diluent acetone at higher temperatures and pressures.
TML may be recovered by scrubbing the vapors with mineral oil,
4.1.1.1 Alloy Manufacture - Sodium-lead alloy is produced
by combining molten lead, virgin or recycled, with molten
sodium at a ratio of 9 to 1 by weight in an alloy pot. The
molten alloy is then solidified and flaked in an oil-cooled'
flaker. The flaked alloy is discharged, under nitrogen
blanket, into the autoclaves. Ethyl chloride is then fed to
the autoclaves over a period of an hour or more. The auto-
4-2
-------
i
U)
TO ETHYL CHLORIDE
RECTIFYING COLUMN
SODIUM
PIG LEAD
LEAD
MELTING
POT
-*«
ALLOY
REACTOR
7")RUPTURE
' DISK
LIQUID
SCRUBBER
STORAGE
VENT
WASTEWATER
VENTED
TO I
BLENDING
WASHING
PURIFICATION
TO INCINERATOR
TO INCINERATOR
©1
*4
STEAM
STILL
ETHYL
CHLORIDE
RECTIFYING
COLUMN
STEAM
FURNACE
AREA VENT
A
VENTURI
SCRUBBER
OR
BAGHOUSE
RECYCLE LEAD
Figure 4-1. Sodium-lead alloy process for the production of tetraethyl lead,
-------
claves are equipped with mixing arms to promote contact
between solids and liquids. To prevent serious explosions
in case of excessive pressure, the autoclaves are equipped
with rupture discs.
4.1.1.2 TEL Manufacture - The batch is initially heated to
start the reaction; the exothermic reaction is then main-
tained dt 70 to 73°C (158 to 167°F) by means of external
coolinj and refluxing of ethyl chloride. About 10 percent
of the alloy is consumed in side reactions, resulting in the
formation of hydrocarbons such as ethane, butane, and ethy-
lene. Uoncoiidensibl.es may be vented directly to the atmos-
phere or incinerated.
4.1.1.3 Alkyl Chloride Separation and Storage - When the
reaction Is complete after several hours, the autoclave
press ir'- is released by venting through a condenser to
i.^ y-7f-'^ excess e-hyl 'hluride, The ethyl chloride is
purl^x-' in a distillation column for reuse. TEL yields are
in the range of 85 to 90 percent.
The reaction mass, containing NaCl, TEL, unreacted
lead, and the remaining dissolved ethyl chloride, is dis-
charged into steam stills to separate the TEL produce from
the other components. In the stills, the dissolved ethyl
chloride is vaporized in the first 10 to 15 minutes of
distillation and is collected by a brine condenser system.
4-4
-------
The collected ethyl chloride is glso purified in a dis-
tillation column and recycled. After this initial period,
only a water-cooled condenser is used to collect TEL and
water at about 20°C (70°F). Noncondensible vapors are
vented to the atmosphere. To prevent agglomeration of the
still residue, "still aids" such as sodium thiosulfate,
ferric chloride, and liquid soap are usually added to the
still. The separation operation lasts for about two hours,
and the residue in the still is then sluiced to a sludge pit
for subsequent lead recovery.
The collected TEL and water mixture is decanted, and
the TEL is purified by air blowing and/or washing with
dilute aqueous solutions of oxidizing agents, such as hydrogen
peroxide. This process oxidizes and precipitates the bismuth
originally present in the raw lead. The clean TEL is filtered,
ethylene dichloride or ethylene dibromide is added to prevent
fouling of spark plugs, and a dye is added to prepare a TEL
motor mix. To prevent oxidation, the TEL motor mix is
usually stored under nitrogen or glycerine.
4.1.1.4 Lead Recovery - The sludge, consisting of fine lead
particles, water, dissolved salt, and traces of TEL, is
leached with water in the sludge pit to separate lead and
salt. The covered sludge pit area is vented with an exhaust
fan to a stack, minimizing the TEL concentration in the air
4-5
-------
of the building. The sludge pit bottoms, mostly lead, are
sent to an indirect steam dryer operated at approximately
177°C (350°F). Water vapor, along with small amounts of
other compounds such as ethyl chloride, is vented from the
dryer through a water-cooled condenser. Noncondensible
vapors from the dryer are sometimes vented through the
sludge pit building.
Dried sludge is fed to a gas or oil-fired reverberatory
furnace to recover lead. In the furnace, slag is tapped for
approximately 15 minutes in every 8-hour period. Molten
lead is tapped from below the slag blanket on a fairly
continuous basis. Makeup lead as required is added to the
molten lead recovered from this furnace. Figure 4-2
illustrates a typical reverberatory furnace.
4.1.1.5 Emissions - TML and TEL are highly toxic and can be
introduced into the blood by contact with the skin or by
breathing the vapors. Emissions sources of lead in a plant
using the sodium-lead alloy process may be grouped in three
categories:
Particulate emissions from the lead recovery
furnace, lead melting furnace, and alloy reactor.
Fugitive emissions in the event of blowing of
rupture discs.
Gaseous discharges containing hydrocarbons and
alkyl lead from all other process vents.
4-6
-------
Figure 4-2. Typical lead reverberatory furnace used
in lead additive manufacturing.
(Courtesy of Aaron Ferrer and Sons, Inc., Los Angeles, Ca.)
4-7
-------
The recovery furnace is a major source of particulate
emissions. The reaction equation given in Section 4.1.1
indicates that about one-third of the lead introduced into
the autoclaves actually reacts to form alkyl lead. Thus,
the recovery furnace processes about 3 times the amount of
lead in the alkyl lead product. The emissions consist
mainly of particulate lead oxide and should be similar to
emissions from any secondary lead smelter except that some
chlorides may also be present.
Uncontrolled lead emissions from the lead recovery
furnace are estimated to be 28 g/kg of alkyl lead product
(55 Ib/ton). Since the material charged to the furnace is
wet, emissions during charging periods are expected to be
minimal.
Other potential sources of particulate emissions are
the melting furnace and alloy reactor. While emissions from
pot furnaces for similar operations could be up to 0.4 g/kg
of charge (0.8 Ib/ton), emissions from the melting furnace
and alloy reactor are reported to be negligible. Emissions
of gaseous hydrocarbons and alkyl lead are also negligible.
Lead emissions, in the form of alkyl lead vapor, from
process vents are estimated at up to 2.0 g/kg product (4.0
Ib/ton) in the TEL manufacturing and 75 g/kg product (150 lb/
ton) in TML manufacturing. The difference in volatility of
4-8
-------
TEL and TML accounts for the difference in vapor emissions.
A sludge pit emission factor is estimated at about 0.6 g
Pb/kg product (1.2 Ib Pb/ton) for the manufacture of both
TEL and TML by the sodium lead alloy process.
Fugitive emissions considered are those resulting from
the blowing of rupture discs. Discussions with manufacturers
indicate that such occurrences are rare. One manufacturer
stated that only two discs ruptured in their TML plants in
1976, while none were blown in TEL production. Currently,
blow-off tanks are the only control device used when a
rupture occurs.
3
4.1.1.6 Control Techniques
A. Lead Recovery Furnace: A number of fabrics are available
for use on the lead recovery furnace. The exhaust gases are
cooled with dilution air or by water spraying to bring the
gases to the temperature range of the fabric filter material.
Filtering velocities used on this type of furnace range from
0.6 to 1.8 cm/s (1.1 to 3.5 fpm). This ratio would depend
on the type of fabric, pressure drop desired, and the bag-
cleaning mechanism. The pressure drop ranges from 1.0 to
2.0 kPa (4 to 8 in. H20). Although use of fabric filters
may entail operational and maintenance problems such as
burning, tearing, and clogging of the bags, a properly
designed and operated fabric filter may easily attain 99
percent or higher efficiency.
4-9
-------
Emissions from the lead recovery furnace are also
controlled with wet scrubbers, constructed of mild steel, of
the orifice, venturi, or packed-tower type, with water as
the scrubbing medium. Scrubber efficiency depends on the
type of scrubber, whether low-energy (80 to 85 percent) or
high-energy (95 to 99 percent). Pressure drop across the
scrubber would depend on the efficiency desired. A high-
energy venturi scrubber with a pressure drop of 10 to 20 kPa
(40 to 80 in. H,0) and liquid-to-gas ratio of 1.1 to 1.3
liters 1/m3 of gas (8 to 10 gal/103 ft ) may attain an
efficiency of 99 percent or higher.
B. Process vents and sludge pits: Some plants use incinerators
to control hydrocarbon emissions. To achieve complete
combustion, the incineration temperature should be 800°C
(1472 ) or higher. Alkyl lead compounds are converted to
inorganic lead particulates during incineration. If streams
relatively rich in lead alkyl could be segregated from lean
stream^, the concentrated streams could be incinerated for
hydrocarbon control and passed through a fabric filter to
control the results at lead particulates. Alternatively,
streams containing high concentrations of alky! lead may be
scrubbed with water prior to combining with lean streams
and incinerating.
4-10
-------
One manufacturer designed for deepwell injection of
aqueous TEL- saturated waste. This manufacturer advises that
he now uses the deepwell for injection of hydrocarbon and
some ethyl chloride, and that the TEL content of this waste
is negligible.
4.1.2 Electrolytic Process
Figure 4-3 is a simplified flow diagram of the electro-
lytic process. The process description here is for pro-
ducing TML; production of TEL is similar except that ethyl
chloride is used instead of methyl chloride.
4.1.2.1 Processes - In the electrolytic process, a solution
of methyl magnesium chloride and methyl chloride is electro-
lyzed with lead metal as the anode, in the following overall
reaction:
2 CH3MgCl + 2 CH3C1 + Pb ->• (CH3>4 Pb + 2 MgCL2
Methylmagnesium chloride, the Grignard reagent, is
prepared by reacting magnesium turnings with excess of
methyl chloride in the presence of ether solvents. This
solution is fed to the electrolytic cells. The cell walls
constitute the cathode, and lead pellets fed at the top of
the cell constitute the anode. Membranes separate the anode
from the cathode.
During the electrolysis, the methyl ions (CH3) migrate
to the lead pellets and form TML as follows:
4 CH3 + Pb - 4e -> (CH3>4 Pb
4-11
-------
Mg
PARTICULATE
'VENT
.WEIGH
HOPPER
Mg
»TURNINGS
MILL
MAGNESIUM
' INGOTS
ETHER
VENT
CH3C1
ETHER
VENT
Mg
ETHER SOLVENT
RECYCLE
CH3C1
I MAKE-U
ETHER
'GRIGNARD
PROPANE DFAfTORkif
'IGFRATTflN Kt^-IUKr^X
REFRIGERATION
Pb
PARTICULATE
LEAD
PELLETS
CH3C1
ETHER
PURIFICATION
'•TML
VENT
RECYCLE'
cffci c W1
ETHER
VENT
STORAGE
HOPPER
(£LL^
CH3C1
ETHER
©
TML
RECTIFIER;
EtCl
REFRIGERATION
ELECTROLYSIS^
CELLS
tcH^Cl VENT
NETHER
STRIPPER
ETHER
MgCl2
TML
TML
RECOVERY
VENT
ETHER
MgCl2
ETHYLENE DIBROMIDE-
ETHYLENE DICHLORIDE-
TOLUENE DYE-
ANT I OX I DANT-
BLENDER
TML
MgCl2
TO REFINERY
TML MOTORMIX
Figure 4-3. Electrolytic process for
»
tetramethyl lead production.
4-12
-------
The magnesium chloride ions (MgCl ) migrate to the cell
walls, where metallic magnesium and magnesium chloride are
formed. When electrolysis is complete, the solution first
goes to a stripper for methyl chloride recovery. The remaining
three compounds are separated by a combination of distillation
and solvent extraction operations. Purified ether and
methyl chloride are recycled to the Grignard reactor, and
the MgCl2 is processed for recovery of magnesium metal. TML
yields are about 96 percent.
The TML is fed into a blender to which ethylene dibro-
mide, ethylene dichloride, toluene, dye, and antioxidant are
added to make a finished motor mix.
4.1.2.2 Emissions - Data on emissions from the electrolytic
process are scarce; only one plant uses this process.
Controlled lead emissions from this plant from all operations
were estimated to be approximately 0.5 g/kg product (1.0
Ib/ton), amounting to approximately 14 Mg of lead (15 tons)
in 1975.3
3
4.1.2.3 Control Techniques - Unlike the sodium-lead alloy
process, electrolytic manufacture does not require a lead
recovery furnace and hence there is no major source of
particulate emissions. It is economically necessary to
recover the ether solvents for recycle. Simultaneously,
some alkyl lead is also recovered by scrubbing.
4-13
-------
This plant uses an elevated flare and a liquid incinerator
to control emissions from process vents. Liquid particles
in the gas stream going to the flare are collected in a
knock-out drum and incinerated periodically, about seven
o
times a year. About 30 to 40 m of liquid waste (6000 to
8000 gal) is incinerated annually.
A scrubber with toluene as the scrubbing medium is used
for controlling emissions from the blending and tank car
loading-unloading systems. No information on the efficiency
of this scrubber is available.
Except for the elevated flare, liquid incinerator, and
scrubber, the electrolytic plant has no equipment installed
expressly for controlling emissions. The entire plant
operates under a gas (nitrogen) padding system, and fugitive
emissions are minimal. In the past, the plant had measured
ambient concentrations of alkyl lead outside the boundary of
the plant; however, the results did not warrant source
testing.
4-14
-------
4.1.3 Control Costs
4.1.3.1 Tetramethyl Lead Production - A 54,400 Mg/yr.
(60,000 TPY) tetramethyl lead model plant was studied to
determine the control costs. Three lead recovery furnaces
are equipped with a cyclone/quench tower/venturi scrubber
system with a design capacity of 7.1 m3/s at 426°C (15,000
acfm at 800°F) and an overall efficiency of 95 percent. The
total lead emissions are 171 kg/hr (377 Ib/hr). Auxiliary
equipment includes I.D. fan system, venturi tank, pumps,
vacuum filter system, and ductwork. A capital cost of
$820,000 is estimated for total installation. An annualized
cost of $417,000 is estimated including utilities, maintenance,
labor, overhead, and fixed costs.a Operating time is assumed
8400 hr/yr and labor requirements are 8400 hr/yr.
Vapors from the process vents in the plant are con-
trolled by a packed bed absorption column. Uncontrolled
emissions are estimated at 450 kg/hr (1000 Ib/hr) TML vapor.
Total capital costs, including ductwork, I.D. fan systems,
hold tank, and pumps, are estimated at $617,000 for an
exhaust flow of 19.7 m3/s at 27°C (41,800 acfm at 80°F).a
Annualized costs are estimated at $353,000, including main-
tenance, labor, utilities, overhead and fixed costs. System
efficiency is 94 percent or greater. Operating time is
estimated at 8400 hours annually. Annual labor is assumed
to be 4200 hours.
a See Section 2.9 and Appendix B for discussion of cost analyses
Detail cost studies are available from EPA upon request.
4-15
-------
Sludge pit exhausts are controlled by similar packed-
bed scrubber system. Capital costs are estimated at $430,000
for a capacity of 13.7 m3/s at 27°C (28,900 acfm at 80°F).
An annualized cost of $277,000 is estimated.3
The total capital for all three systems is $1.87
million. Total annualized costs are $1.05 million or about
1.94$/kg (0.88<=/lb) of TML product.
4.1.3.2 Tetraethyl Lead Production - A 54,400 Mg/yr.
(60,000 TPY) tetraethyl lead model plant was also studied to
determine control costs. The recovery furnace and sludge
pit control systems are identical to the systems discussed
above. Process vents in the model TEL plant exhaust 10.9
m /s at 27°C (23,000 acfm at 80°F) to a packed-bed scrubber
system with an efficiency of 95 percent. Uncontrolled
emissions are 1.6 kg/hr (3.6 Ib/hr) TEL vapor. Capital
costs for this system are estimated at $359,000 including
ductwork, I.D. fan, hold tank, and pumps. Annualized costs
are determined to be $245,000, including maintenance, labor,
overhead, utilities, and fixed costs.a Annual operating
time is 8400 hours and annual labor time is 4300 hours.
The total capital costs for all three control systems
are estimated at $1.61 million. Annualized costs are
determined to be $939,000 or about 1.72C/kg (0.78£/lb) of
TEL product.
See Section 2.9 and Appendix B for discussion of cost analyses
Detailed cost studies are available from EPA upon reques?
4-16
-------
4.1.3.3 Cost Equations - The capital and annualized costs
for the recovery furnace/venturi scrubbing system are expressed
below in terms of exhaust volume and annual labor hours:
S.I. Units
Capital, $ = 2.53 x 105V°'6
Annualized, $ = 3516V + 19.6H + 68,900V0'6
V = m3/s at 427°C
H = annual labor hours
2.4 < V < 21
range
English units
Capital, $ = 2560Q0'6
Annualized, $ = 1.66Q + 19.6H + 696Q0'6
0 = acfm at 800°F
H= annual labor hours
5,000
-------
9 < V < 28
range
English units
Capital, $ = 13.85Q + 36,100
Annualized, $ = 5.77Q + 19.6H + 25,600
Q = acfm at 80°F
H = annual labor hours
20,000 < Q < 60,000
range
4-18
-------
As chapter two states,the preceding costs have been
based on exhaust gas parameters and control system config-
urations tailored to typical existing TEL and TML plants.
However, control costs at an actual lead additives plant
could vary considerably from the above, due to unique con-
ditions specific to that installation.
For instance, one major additives producer has provided
costs for controlling the several process points at his
c p.
plant. ' To control the three lead recovery furnaces with
baghouses, this producer estimates a required investment of
$1.5 to $2.0 million--a figure which includes pelletizers
for processing the captured dust before recycling to a
secondary lead smelter. This high capital cost is necessary
to treat the large gas volume (37,000 ACFM at 350°F) which
is, in turn, created by large quantities of dilution air.
The manufacturer also gives a $900,000 installed cost
for a packed scrubber system on the TML process vent, based
on a design flowrate of 1500 SCFM. (This cost has been
escalated from a $400,000 system, installed in 1968). This
is 46 percent higher than the $617,000 investment (shown on
page 4-15) which is based on 41,800 ACFM at 80°F. However,
the control system designs are vastly different. The EPA
system consists of a packed scrubber (using water), fan
system, ductwork, holding tank, and pumps. The manufacturer's
system includes all of these plus a stripper - cooler system
for separating the absorbent (a kerosene absorbing oil) from
the captured alkyl vapor.
4-19
-------
A similar packed bed scrubber system to control the sludge
pit exhaust in a model TEL or TML plant would require an investment
of $2.5 to 3.0 million, according to this manufacturer. This is
substantially higher than the EPA costs ($430,000), again because
the manufacturer's system is much more complex.
Finally, the manufacturer notes that the EPA investment figure
given for the TEL process vent packed scrubber system is much too
low. The manufacturer neglects to give his estimate of a scrubber
system cost. However, he notes that TEL cannot be recovered from
absorbing oil, as can TML. Thus, packed scrubbing is not a
technologically feasible control method here. As an alternative,
he suggests incineration of the process vent, followed by collection
of the resultant particulate lead in baghouses.
4.1.4 Impacts
A. Emission Reductions
Lead emission reductions from lead recovery furnaces are
up to 28 kg/Mg of alkyl lead product (55 Ib/ton). Particulate
emissions from pot furnaces can be reduced by 0.4 kg/Mg charge
(0.8 Ib/ton). Alkyl lead vapors from process vents can be reduced
by up to 2.0 kg/Mg product (4.0 Ib/ton) for TEL production and up
to 75 kg/Mg product (150 Ib/ton) for TML production. Sludge pit
lead emissions can be reduced by about 0.6 kg/Mg product (1.2
Ib/ton).
4-20
-------
B. Energy Impact
Data for energy requirements to product TEL and TML are
not available. The energy required to operate the control
equipment on the model processes are as follows: recovery
furnace/venturi scrubber, 0.04 GJ/Mg lead (0.04 MM Btu/ton);
sludge pit/packed tower, 0.13 GJ/Mg throughput (0.13 MM Btu/ton);
TML process vent/packed tower, 0.17 GJ/Mg throughput (0.17 MM
Btu/ton); and TEL process vent/packed tower, 0.11 GJ/Mg
throughput (0.11 MM Btu/ton).
C. Wastewater Impact
The amount of wastewater generated to produce TML or TEL
is not available. The wastewater generated requiring treatment
amounts to about 0.42 m3/Mg lead (100 gal/ton) for the model
recovery furnace scrubber systems. The process vent-gas
•D
absorption columns discharge 0.70 m /Mg product (170
gal/ton) and 1.3 m /Mg product (320 gal/ton) for TML and
TEL manufacturing, respectively. Large treatment plants
are on-site to treat contaminated wastewater. Increased
wastewater volume from air r-ollution control equipment is not
expected to require additional treatment equipment.
D. Solid Waste Impact
Data on solid wastes generated by TEL and TML production
are not available. Solid wastes from emission control
equipment from recovery furnaces containing about 110 kg/Mg
product (55 Ib/ton) of lead are recycled. Therefore, the
solid waste impact from emission control will not be significant.
4-21
-------
4.1.5 References for Section 4.1
1. Lead Industry in October 1975. Mineral Industry
Survey. U. S. Bureau of Mines. Washington, B.C.
October 1975.
2. Chemical Engineering. McGraw-Hill. New York, N.Y.
April 28, 1975. p/109.
3. Background Information in Support of the Development
of Performance Standards for the Lead Additive Industry,
Interim Report No. 2. PEDCo-Environmental Specialists,
Inc. Cincinnati, Ohio. r^ Environmental Protection
Agency, Research Triangle 'ark, N.C. Contract No.
68-02-2085. January 1976
4. Betz, R. P. et al. Economics of Lead Removal in
Selected Industries. Battelle Columbus Laboratories.
Columbus, Ohio. For U. S. Environmental Protection
Agency, Research Triangle Park, N. C. Contract No.
68-02-0611. August 31, 1973.
5. Private communication between E. N. Heltners,
Engineering Department, E. I. du Pont de Nemours
and Company, Inc. (Wilmington, Del) and D. R.
Goodwin, Office of Air Quality Planning and Standards,
U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina. March 1, 1977.
6. Private communication between W. M. Vatavuk, Office
of Air Quality Planning and Standards, U. S.
Environmental Protection Agency, Research Triangle
Park, North Carolina, and W. S. Murray, Inorganic
Chemicals Department, E. I. du Pont de Nemours and
Company, Inc. (Deepwater, N.J.). March 25, 1977.
4-22
-------
4.2 STORAGE BATTERY MANUFACTURE
Manufacture of lead-acid storage batteries in 1975
decreased over 11 percent from the previous year to 48,325,000
1 2
batteries, ' accounting for 54 percent of the 1.176 Tg of
q
lead (1.297 million tons) consumed in the United States. A
total plant emission factor of 8.0 kg/1000 batteries pro-
duced ' ' (17.7 Ib Pb/1000 batteries) is estimated, excluding
lead oxide production. Manufacture of storage batteries
accounted for approximately 82 Mg of lead emissions (90 tons)
nationwide in 1975. The associated production of lead oxide
caused the emission of 80 Mg of lead (88 tons).
4.2.1 Processes and Emissions
A flow diagram for a typical lead-acid battery manu-
facturing plant is given in Figure 4-4. Lead oxide manu-
facturing may or may not be carried on at the plant. A
detailed description of lead oxide mills is given in Section
4.6.
4.2.1.1 Grid Casting - Casting techniques for battery grids
vary with the alloy used, the type of molds, and mold prep-
aration before casting. Lead alloy ingots are melted in a
gas-fired lead pot at approximately 370°C (700°F). The
furnace is often equipped with a hood to vent the fumes to
a control device or to the atmosphere. Melting pots are
attached directly to some grid casting machines. The molten
4-23
-------
LEAD ALLOY
REFINED LEAD
1 DUST AND FUM' '
I A DM
OXIDE
PRODUCTION
-
OXIDE
PASTE
PREPARATION
_J
DUST
t s
)SS
JLFATE
PASTE _J
PASTED
i
i
BATTERY
ASSEMBLY
•
-
TERMINAL
ASSEMBLY
.
'
PLATE FORMING
\
r
I
GRID CASTING
i
GRID CASTING
1
GRID PASTING
GRIDS ]
DUST
t
»
\
1
PLATE FORMING
•
BATTERV
ASSEMBLY
]
TERM
ASSE
-
INAL
MBLY
FUME
A
f
FUME
1 1
DUST
i— !
FUME
i
WET CHARGE BATTERY
DRY CHARGE BATTERY
t: 4-4. Flow diagram of a lead-acid battery plant.
4-24
-------
lead flows from these pots directly into the molds that form
the grids; they are then ejected, trimmed, and stacked.
Some facilities feed the molding machines from a central pot
furnace, from which the molten lead is pumped.
4.2.1.2 Paste Mixing - The paste making operation, a batch-
type process, takes place in a Muller, Day, or dough-type
mixer. From 272 to 1360 kg (600 to 3000 Ib) of lead oxide
(a mixture of PbO and Pb) is loaded manually or automatic-
ally to the mixer. Water, varying amounts of sulfuric acid,
an organic expander, and other constituents are added,
depending on whether the paste batch is for positive or
negative plates. The mixture is blended to form a stiff
paste. Because of the exothermic conditions, mixers are
usually water-jacketed and air-cooled to prevent excessive
temperature buildup which causes the paste to become stiff
and difficult to apply to the grids. A duct system vents
the exhaust gases from the mixer and loading station to a
control device.
Duration of the mixing cycle is dependent on the type
of mixer used, ranging from 15 minutes to an hour.
4.2.1.3 Grid Pasting - Pasting machines force the lead
sulfate paste into the interstices of the grid structure at
rates exceeding 200 plates per minute (the grids are called
plates after the paste has been applied). The freshly
4-25
-------
pasted plates are transported by a horizontal chair through
a temperature-controlled heated tunnel about 6m (20 feet)
long, where the surface water is removed. This allows the
plates to be stacked without sticking together. No emission
control is generally provided or needed for grid pasting and
plate drying operations. The floor area around pasting
operations must be kept clean of paste, however, since this
is a potential source of fugit./e dust. The plates are
cured for up to 72 hours. Following the curing stage, the
plates are sent to the assembly operations where they are
stacked in an alternating positive and negative block for-
mation. Insulators are sandwiched between each plate to
insulate the oppositely charged plates. These dividers are
made from materials such as wood, treated paper, plastics,
or rubber. Although machines have been designed that can
stack the plates and separators automatically, hand stacking
J.S iioL uiioOiiuiiorif cTvoii in sGiiifc: relatively large plants.
4.2.1.4 Lead Burning - Leads (pronounced leeds) are welded
to the tabs of each positive plate and each negative plate,
fastening the assembly (element) together: this is the
burning operation. An alternative to the welding or burning
process is the "cast-on-strap" process. In the latter,
molten lead is poured around and between the plate tabs,
thus forming the connection. Then a positive and a negative
4-26
-------
terminal are welded to the element. The completed elements
can go to either the wet or dry battery lines.
4.2.1.5 Battery Assembly - In the wet battery line, ele-
ments are placed within cases made of durable plastic or
hard rubber. Covers equipped with openings and lead inserts
are aligned so that the terminals project from the inserts.
The covers are sealed to the cases and the batteries are
filled with dilute sulfuric acid and made ready for forma-
tion.
For dry batteries the elements are formed prior to
being placed in a sealed case. The dry batteries are
shipped without acid.
4.2.1.6 Formation - Formation is a chemical process wherein
the inactive lead oxide-sulfate paste is converted into an
active electrode. Formation is essentially an oxidation-
reduction reaction, wherein the positive plates are oxidized
from lead oxide to lead peroxide and the negative plates are
reduced from lead oxide to metallic lead. This is accom-
panied by placing the unformed plates in a dilute sulfuric
acid solution and connecting the positive plates to the
positive pole of a d.c. source and the negative plates to
the negative pole of the d.c. source.
4,2.1.7 Lead Recovery - All batteries are inspected during
manufacturing. The various metallic parts such as grids,
4-27
-------
posts, and connectors, if not satisfactory for production
use, are remelted for reuse.
Pot-type furnaces are generally used for reclaiming
scrap lead at battery manufacturing plants. Defective lead
parts are collected and stored until a sufficient amount is
available for charging a reuniting furnace, usually gas-fired.
Emissions from remelting furnaces resemble those from grid
casting. Because of the relatively low operating temperatures
emission concentrations are low. Emissions generally are
visible only when oily scrap or floor sweepings are charged.
Many plants send scrap parts to an outside smelter. Some
plants feed scrap plates to a tumbling operation to separate
the lead paste from the grids. The separated paste is then
sent to the paste mixer, and the grids are remelted.
4.2.1.8 Emissions - Table 4-1 presents characteristics of
exhaust gas from the various sources within a battery plant.
A typical uncontrolled lead emission factor is estimated at
8.0 kg/1000 batteries (17.7 lb/1000 batteries). For a
production rate of 48,325,000 batteries and an overall
Q
industry emission control of 80 percent , the 1975 lead
emissions were about 82 Mg (90 tons).
There are no significant sources of lead fugitive
emissions at a battery plant if good housekeeping is prac-
4-28
-------
Table 4-1. TYPICAL EXHAUST PARAMETERS FOR BATTERY MANUFACTURING OPERATIONS
racilit>
code
letter
A
B
C
D
E
F
G
H
Facility
Grid casting
furnaceb
Grid casting
machine"
Paste mixer
Lead oxide
rrilic
Three-process
operation^
Lead reclaim
furnace
Small Darts
castino
Formation
'emperature
°C
16
38
38
116
27
116
38
27
T^F)
(240)
(100)
(100)
(240)
(80)
(240)
(100)
(80)
Percent
moisture
2-3
2-3
2-4
2-3
1-2
2-3
1-2
N.A.
Particulate
qrain loading
g/m3
<0.02
<0.02
0.14
0.02
0.05
>0.02
0.02
3.68
(qr/scf)
(<0.01)
(<0.01)
(0.06)
(0.009)6
(0.02)
;>o.io)
(0.01)
(1.6)f
(H2S04)
Gas Volume, m3/s (acfm) Emissions, kg (Ib)/I03
batteries
500 BPD
1.18 (2,500)
1.18 (2,500)
0.38 (800)
c (c)
8.50 (18,000)
3.30 (7,000)
1.89 (4,000)
2.36 (5,000)
2000 PPD
1.89 (4,000)
1.89 (4,000)
1.42 (3,000)
0.66 (1,400)
12.27 (26,000)
3.30 (7,000)
1.89 (4,000)
9.44 (20,000)
6500 BPD
4.25 (9,000)
4.25 (9,000)
4.72 (10,000)
2.08 (4,400)
24.5 (52,000)
3.30 (7,000)
1.89 (4, '00)
Particulate11
\Q.8 (1.8)
/
1.00 (2.2)
0.10 (0.24)
13.2 (29.2)
0.70 (1 54)
0.09 (0.19)
30.7 (65,000)14.0 (32.0)
(H2so4) (H2sn,)
Lead
0.4 (0.9)
0.5 (1.10)
0.05 (0.12)
6.60 (14.6)
0.35 (0.77)
0.05 (0.10)
N.A. N.A.
3 Based on exhaust data obtained from plant representatives and various source test reports. References 5, 6, 7, and 8.
b The grid casting facility consists of a furnace and a machine. Sometimes these elements are separate—such as where
one furnace feeds many casting machines.
c For purposes of this study, it is assumed that plants making only 500 BPD (batteries per day) will not have PbO
manufacturing facilities.
The three-process operation consists of element stacking, lead burning, and battery casing.
6 Measured at outlet of baghouse which is part of the process.
Test data from outlet of fan separator tested at plcnt indicated <10 ppm H-S04 (<0.017 gr/dscf); assuming control
device was 99% efficient, uncontrolled emission approximates 1.6 gr/dscf.
" Tests made during this study only measured lead. However, other contaminants, such as hits of material from
seoarators, cork from the mold release agent, and the like must be considered. It is estimated that lead
constituted at least 50 percent of the total particulate matter.
-------
ticed. The formation process does not contribute lead
emissions.
4.2.2 Control Techniques
Grid casting furnaces and machines, paste mixers, plate
dryers, reclaim furnaces, and parts casting operations can
be controlled by low to medium-energy impingement and
entrainment scrubbers. A pressure drop of 2 to 2.5 kPa (8
to 10 inches) W.G. and a liqui -to-gas ratio of 0.54 liter/m
(4 gal/10 ft ) are common, yielding a control efficiency of
o
85 to 90 percent or higher.
Grid casting machines, paste mixers, plate dryers, the
three-process operation, and parts casting machine can be
controlled by a pulse-jet fabric filter with a filtering
velocity of 3 to 4 cm/s (6 to 8 fpm) yielding a control
Q
efficiency of 95 to 99 percent or higher.
Alternatively, grid casting furnaces and machines,
plate dryers, and parts casting machines are commonly uncon-
trolled. These processes are relatively minor sources of
g
lead emissions.
Lead oxide mills are controlled by automatic shaker-
type fabric filters with filter velocities of 0.5 to 1.5
cm/s (1 to 3 fpm), yielding efficiencies of 99 percent or
greater. These fabric filters are often preceded by cyclone
mechanical collectors. The entire control system is con-
4-30
-------
sidered product recovery equipment and not air pollution
Q
control.
Waste material caught in the control systems is
recycled to recover the lead content.
Table 4-2 summarizes viable control alternatives and
associated control costs for new battery plants.
Preliminary results of a recent EPA test program to
develop lead emission standards for new battery plants are
shown in Figure 4-5 and Table 4-3. Table 4-3 shows expected
efficiency of well-designed and properly operated control
devices for lead emissions emanating from various operations.
Figure 4-5 indicates the average controlled emission con-
centration from these processes.
4.2.3 Control Costs
Table 4-2 summarizes the capital and annualized
control costs estimated for three new model plant sizes.
The capital costs represent the total equipment costs,
including ductwork and installation. Annualized costs
include operating and fixed costs. Capital costs for
retrofitted equipment will be approximately 20 percent
higher, and annualized costs will be from 10 to 12 percent
higher.
4-31
-------
Table 4-2. LEAD CONTROL TECHNIQUES AND ASSOCIATED COSTS
FOR NEW LEAD-ACID BATTERY PLANTS
I
to
to
Al ternati ve
I
II
III
IV
V
Control Techniques
Fabric fil terb
A, B. F
D
B, C, E
0
C, E
D
E
D
E
D
Wet collector0
none
r
A. B, f
f
A, B, C
A, B, C, F
Lead Control Efficiency
(Percent)
99.
98.
98.
95.
95.
Control Costs, $103 (1976)
500 EPD
Capital
173
192
160
191
158
Annual i zed
41
48
38
48
38
2000 BPD
Capital
233
247
211
237
202
Annual i zed
67
74
63
71
61
6500 BPD
Capital
428
413
365
378
335
Annual ized
122
122
108
115
102
aThe letters refer to the following processes: A = grid casting furnace, B = grid casting machine, C = paste mixer, D = lead oxide mill,
E = three-process operation (stacking, burning, casting), F = lead reclaim furnace.
Pulse-jet (filtering velocity: 3 to 4 cm/s (6 to 8 fpm)) fabric filter on all processes; lead oxide mill (D) where automatic shaker
type fabric filter (filtering velocity: 1 cm/s (2 fpm)) Is employed. Control costs for lead oxide mill is a differential cost incurred
by decreasing filtering velocity by 30 percent.
cLow energy impingement and entrainment scrubber; AP = 2 to 2.5 kPa ( 8 to 10 in. wg), and L/G « 0.5 liter/m3 gas (4 gal/103 ft3).
-------
0.COT SO
O.OGKO -
0.00120
0.00100
-> G.C0050
0.00020
PROC'SS
CC-lT'.CL'
PLANT
SRID
CAST
GRID
CAST
A'lO
FULL MXI'IG
MIX
GaiD SLITTING SLITTING SLITTING TH'FE-PWCESS °bO LEAD
CAST ANO Fi'LL AND '^IVE^ O^fvATICN PRO^'^TION DECLAI
A'lQ -
BH
0
3H
0
BH
0
BH
0
BH
CS
G
Figure 4-5. Average controlled lead emissions from
tested facilities (gr/dscf).
4-33
-------
Table 4-3 LEAD REMOVAL EFFICIENCY
FOR WELL-CONTROLLED PROCESSES10
Process operation
Control device
Lead removal
efficiency, percent
Grid casting
Paste mixing cycle
and grid casting
Paste mixing charging
and plate slitting
Three-process operation
Paste charging and
plate slitting
Lead reclaim
Type-N rotoclone
Type-N rotocolone
Fabric filter
Fabric filter
Fabric filter
Cascade scrubber
94
90
98
90
98
98
4-34
-------
4.2.4 Impacts
A. Emission Reduction Benefits
The application of NSPS level controls are assumed to
enable a plant to meet NAAQS for lead. Regardless of plant
size, particulate emission reductions are estimated at 10 to
13 kg (23-28 Ib) per thousand batteries produced, with a
lead content of 50 percent by weight. Depending on the
control strategy, this represents a reduction of uncontrolled
particulate and lead emissions from 82 to 98 percent. With
the production of nearly 55 million battery units, nation-
wide lead emissions can be reduced by only 350 Mg (390
tons), about 0.2 percent of the total lead emissions to the
atmosphere.
B. Energy Impacts
The process energy required for the operation of a
large 6500 battery per day plant is about 60 GJ (60 MM Btu)
per thousand batteries produced. An additional 0.4 GJ (0.4
MM Btu) per thousand batteries is required to operate SIP
controls and 2.3 GJ (2.3 MM Btu) per thousand batteries to
operate NSPS controls. These energy impacts represent
increases of 0.7 percent (SIP) and 4.1 percent (NSPS).
The process energy required to operate a small, 500 bpd
plant is about 220 GJ (220 MM Btu) per thousand batteries.
The additional energy needed to operate SIP controls is
4-35
-------
estimated at 0=9 GJ (0.9 MM Btu) per thousand batteries (a
0.4 percent increase). NSPS controls require about 3.3 GJ
(3.3 MM Btu) per thousand batteries (a 1.5 percent increase).
C. Water Pollution Impact
The increase of wastewater flow and pollutant loadings
depends upon the control configuration. A plant with only
fabric filter controls will cause an increase in wastewater
generation. The typical wastewater flow from a battery
plant is about 270 liters (70 gal) per battery. The lead
content of this wastewater is less than 25 ppm. Lead
loadings in the wastewater are about 11 kg (25 Ib) per
thousand batteries.
With the application of NSPS controls, the maximum
increase in wastewater flow is 11 to 26 1pm (3 to 7 gpm) or
about 1 to 3 percent more. Lead discharges may increase
only 0.04 to 0.5 kg (0.09 to 1.0 Ib) per thousand batteries,
or about 0.4 to 5 percent.
D. Solid Waste Impact10
The only significant source of solid wastes in a
battery plant is wastewater treatment when acid-lime neutra-
lization is utilized. About 11 Mg (12 tons) of solid wastes
are generated per thousand batteries.
By the application of NSPS controls the maximum impact
on solid waste generation is estimated at 40 kg (80 Ib) per
thousand batteries of which 50 percent is lead. This amounts
to an impact of only 0.3 percent.
4-36
-------
4.2.5 References for Section 4.2
1. Breese, Frank. 1976 National Petroleum News Factbook.
Mid-May 1976. p. 108.
2. 1973 Minerals Yearbook. Volume I-II. U. S. Department
of the Interior. Bureau of Mines. Washington, D. C.
3. Lead Industry in October 1975. Mineral Industry
Surveys. U. S. Bureau of Mines. U. S. Department
of the Interior. Washington, D. C. October 1975.
4. Kulujian, N. Test No. 74-BAT-l, ESB, Inc. Milpitas,
California, September 1973. PEDCo-Environmental
Specialists, Inc. Cincinnati, Ohio. For U. S.
Environmental Protection Agency. Contract No. 68-02-
0237. Task 28. March 1974.
5. Screening Study to Develop Background Information and
Determine the Significance of Emissions from the Lead-
Acid Battery Industry. Vulcan-Cincinnati, Inc. For
U. S. Environmental Protection Agency. Contract No.
68-02-0299. Task Order 3. December 4, 1972.
6. Confidential test data from a major battery manufacturer.
July 1973.
7. Particulate and Lead Emission Measurements from Lead
Oxide Plants. Monsanto Research Corporation. EPA
Contract No. 68-02-0226. Task 10. August 1973.
8. Background Information in Support of the Development of
Performance Standards for the Lead Acid Battery Industry.
Interim Report No. 2. PEDCo-Environmental Specialists, Inc.
Cincinnati, Ohio. For U. S. Environmental Protection
Agency, Contract No. 68-02-2085. December 1975.
9. Trip Report. General Battery Corporation. Reading,
Pennsylvania. By PEDCo-Environmental Specialists, Inc.
Cincinnati, Ohio. For U. S. Environmental Protection
Agency. Contract No. 68-02-2085. August 11, 1975.
10. Background Information in Support of the Development
of Performance Standards for the Lead-Acid Battery Industry,
Interim Report. No. 3. PEDCo-Environmental Specialists,
Inc. Cincinnati, Ohio. For U. S. Environmental
Protection Agency. Contract No. 68-02-2085. December 1976
4-37
-------
4.3 PRIMARY NON-FERROUS METALS PRODUCTION
A total of 2.32 Gg (2,552 tons) of lead emissions was
generated in 1975 by production of primary non-ferrous
metals. Lead emissions are estimated for the following
sources: ore mining, crushing, and grinding, 493 Mg (544
tons); primary lead smelting, 400 Mg (440 tons); primary
zinc smelting, 112 Mg (124 tons); and primary copper smelting,
1314 Mg (1444 tons).
4.3.1 Ore Mining, Crushing, and Grinding
Lead and zinc ores are normally deep mined, whereas
copper ores are open-pit mined, chiefly in the far West.
Lead, zinc, and copper occur in the ore in various amounts.
If the metal content is high enough for economical extraction,
the ore is listed as a mixed ore, i.e., lead-zinc, copper-
lead. The 1974 output for the different ores is shown in
Table 4-4. Lead emissions resulting from this activity are
estimated at 493 Mg (544 tons).
4.3.1.1 Process Description - Lead, zinc, and copper ores
are generally concentrated in a liquid medium using settling
arid flotation. The common form of the metal in the ore is
in a mineral combination with sulfur and/or oxygen. Lead,
zinc, and copper are usually mixed together in varying
percentages. Depending on the amount of each of these
4-38
-------
Table 4-4. LEAD EMISSIONS FROM ORE GRINDING AND CRUSHING OPERATIONS
Type of
ore
Pb
Zn
Pb-Zn
Cu-Pb
Cu-Zn
Cu-Pb-Zn
Cu
Ore processed,
Tg
8.46
5.98
1.82
0.75
0.74
59.3
242
(10t> ton)
(9.33)
(6.59)
(2.01)
(0.83)
(0.82)
(65.4)
(267)
Pb 1 2 4
content, '*'*
% wt
5.1
0.2
2.0
2.0
0.2
2.0
0.2
Particulate
emissions,
g/kg
3.0
3.0
3.0
3.2
3.2
3.2
3.2
(Ib/ton)
(6.0)
(6.0)
(6.0)
(6.4)
(6.4)
(6.4)
(6.4)
% Uncontrolled
25
25
25
75
75
75
Suspended
emissions, %
25
25
25
10
10
10
75 10
Total lead emissions, Mg (ton)
Suspended
lead emissions,
Mg
81.0
2.0
6.0
4 . 0
Neg.
284
116
493
(tons)
(89.3)
(2.2)
(6.6)
(4.4)
(Neg. )
(313)
(128)
(544)
I
OJ
-------
metals in the ore and on the potential economic return, the
metals are either separated from the ore or discarded in the
tailings.
The ore in underground mines is disintegrated by light-
weight percussive and rotary percussive drilling machines.
Power shovels, front-end loaders, scrapers, and mucking
machines load the pulverized ore into electric or diesel-
powered motorized trains operating on heavy-gage tracks, or
into trackless shuttle cars. The ore is commonly run
through a primary crusher underground and then conveyed by
skip loader, rail tram, or conveyor belt (depending on mine
depth) to the surface, where classifying and additional
grinding occur. Figure 4-6 illustrates a typical ore
crushing and grinding operation.
Lead and zinc ores are concentrated to 45 to 75 percent
concentration before going to the smelter. Depending on the
mineral form and gangue material, the ore is crushed and
ground to a size based on an economic balance between the
recoverable metal values and the cost of grinding. Standard
jaw, gyratory, and cone crushers, vibrating or trommel
screens, and rod and ball mills are used to reduce the ore
to a powder in the 65 to 325 mesh range. Through gravity
and/or selective flotation the finely divided particles of
copper, lead and zinc are separated from the gangue and are
cleaned, thickened, filtered, and dried.
4-40
-------
,' , •„',''.'" "'-",> Pnnjry CrusM
• • ,L.,-;.I\, ,c ---'.'tres'n OK ii.i
1 -C*"" IF ** * - * •' -'*"-. L */* * '" ^-- t.*>'-,- ''^tr'- -r;,"*^, ^, *- X it)''i''",*' ^-^
«Ca-rttj'ci AMAX ^taJ^c-^.; # 3'tM MC^J •*,'•-.% • » VJ "rf- *" "' T^ "*/• j'-r^x.~.' ^^ " T -v *"'"*"-' ',
';cKr^"-^'^^>>X^;^^-v.%^^l;rtv,^t'^^ L!v^^
Figure 4-6, A typical ore mining and processing operation.
-------
About 89 percent of the copper ore mined in 1974 was
from open pit mines; copper concentration in the ore ranges
from 0.4 to 1.0 percent. The other 11 percent was extracted
from underground mines, with copper content ranging from
1.0 to 4.5 percent. This ore is handled essentially the
same as zinc and lead ores.
Open-pit mining for copper, copper-lead, copper-zinc,
and copper-lead-zinc ores is centered primarily in the far
West in arid or semi-arid areas. The ore and gangue are
loosened and pulverized by explosives, scooped up by power
shovels or other mechanical equipment, and loaded into
trucks, rail trains, or cars for transport to the concentra-
tor. The ore is then processed in the same manner as lead
and zinc ores.
4.3.1.2 Emissions - Lead emissions are basically fugitive,
caused by drilling, blasting, loading, conveying, screening,
unloading, crushing, and grinding. Underground mines con-
tain the emissions from ore mining operations. Particu-
late emissions from open-pit mining are about 0.2 g/kg of
ore handled (0.4 Ib/ton). Transport and storage operations
emit about 2.0 g/kg (4.0 Ib/ton), and fugitive particulate
emissions from crushing and grinding are about 1.0 g/kg (2.0
Ib/ton).4
4-42
-------
Because of the large particle sizes and high specific
gravities (5.7 to 7.6) of emissions from this source, fall-
out of the particulate matter occurs within a short distance
of the point of emission.
4.3.1.3 Control Techniques - The primary means of control-
ling emissions from crushing and grinding operations are
good mining techniques and equipment maintenance. Opera-
tions at the southeast Missouri lead belt located in the
Clark National Forest region include a number of practices
that minimize dust emissions. The ore is mined underground
at depths of 210 to 370 m (700 to 1200 ft), and the truck
loading operation is enclosed. The truck load itself is
wetted or covered. The roads from mines to the concentra-
tors are paved, the unloading area is sprinkled, and the
crushing and grinding enclosures are well maintained to
prevent leaks. The concentrates are stored under roof or
wetted to prevent blowing, and the paved area around the
concentrator drains into containment ponds. In 1974, this
region furnished 85 percent of the mine-produced lead in the
U.S.2
4.3.2 Primary Lead Production
In 1975, about 582 Gg of lead (642,000 tons) was pro-
duced by the primary lead industry. Total domestic con-
sumption of lead was about 1.18 Tg (1.30 x 10 tons).
Primary lead smelting occurred at six locations.
4-43
-------
Total particulate emissions resulting from primary lead
production in 1975 are estimated at 1.136 Gg (1250 tons).
Assuming an average lead content of 35 percent in the
particulates, ' ' ' ' lead emissions amounted to 400 Mg
(440 tons). This estimate does not include possibly signi-
ficant fugitive dust emissions from mining, material trans-
port, concentrators, furnaces, and ductwork. Emission
estimates for the ore mining, crushing, and grinding phase
are given in section 4.3.1.2.
4.3.2.1 Process and Emissions - The three major lead emis-
sion sources are sintering machines, blast furnaces, and
dross reverberatory furnaces. Figure 4-7 illustrates typi-
cal processes and emission points in domestic primary lead
smelters and refiners. Process and fugitive dust emissions
are discussed separately where applicable.
A. Sintering:
Process - Sintering, the first pyrometallurgical process
that is performed on all lead concentrates, serves the
following functions:
1) Providing a feed with the proper ratio of lead,
silica, sulfur, and iron for subsequent smelting
operations.
2) Converting metallic sulfides into oxides and
sulfates amenable to smelting.
3) Purifying the concentrate by volatilizing contami-
nants such as arsenic, tellurium, and antimony.
4) Producing a firm, porous clinger that is suitable
for blast furnace smelting.
4-44
-------
Figure 4-7. Flow diagram of primary lead smelter.
[Key: O~ ai-r emission, /\- wastewater discharge, |~~1- solid waste]
-------
In an updraft sintering machine, combustion air is
passed upward, and in a downdraft machine, air is sucked
downward through the charge. Only one primary lead smelter
uses a downdraft sintering machine. Capacities range from
0.91 to 2.27 Gg (1000 to 2500 tons) per day. The bed area
for a machine of 910 Mg (1000 ton) per day capacity is 2 m
13 14
by 22 m (8 by 72 ft). ' Figure 4-8 shows an updraft sin-
tering machine.
Lead concentrates account for 30 to 35 percent of the
input material for the sintering process. Approximately 83
percent of these concentrates, which contain 70 to 76 percent
lead come from the new Missouri lead belt. ' The remainder
of the lead concentrates, from western and foreign sources,
contain 45 to 60 percent lead.
STRONG GAS TO DEDUSTING
I
RECIRCULATING STREAM
FRESH AIR
FRESH AIR
SINTER
Figure 4-8. Lead updraft sintering machine.
7
4-46
-------
Emissions - The sintering machine is a major source of
atmospheric emissions from primary lead smelters. Table 4-5
gives exhaust gas characteristics for this process.
A major gaseous constituent of sintering off-gas is
SG>2. There are three methods of handling the gas streams,
based on treatment of the SO2. The simplest method is
venting of all gases in a single stream. The second method
segregates the gases that are formed in the front of the
sinter machine from those that are formed toward the rear,
producing a strong and a weak SO~ gas stream. The third
method also separates the gases into a strong and a weak
SO.., exhaust gas stream but continuously recirculates the
weak stream through the sinter machine. The first method
produces a stream with SO,, concentration of less than 3
percent by volume. The strong and weak gas streams of the
second method contain 6.5 percent and 0.5 percent S02, re-
spectively. The third method produces an exhaust gas with
an SO- concentration of 4 to 6 percent by volume.
Published estimates of total particulate emissions and
lead content vary considerably, usually with no indication
of the type of sintering machine or gas venting system.
The validity of these data is questionable. Lead content of
8 9
the particulate emissions ranges from 20 to 65 percent. '
On the basis of EPA emission factors, the lead emission
factors range from 4.2 to 170 g/kg of lead product (8.4-340
lb/ ton).8'9'18'19'20'21
4-47
-------
Table 4-5. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM LEAD SINTER MACHINE
Parameters
Gas flow rate3
Temperature3
Grain loading
Particle size
distribution
Lead content
of particulate
Emission factors
0 particulate
0 lead
Standard
international
units
1.1 m /s.Mg-h"1
product
650°C
2-57. g/m3
15-45%w
English
units
2200 scfm/tph
product
1200°F
0.87-25 gr/scf
< 20-40 ym
9-30%w < 10-20 ym
4-19%w < 5-10 ym
l-10%w
20-65%w
3
21-260 g/kg Pb
produced
4.2-170 g/kg
Pb produced
< 5 ym
20-65%w
42-520 Ib/ton Pb
produced
8.4-340 Ib/ton
Pb produced
References
10
10
8, 9, 18
9
8, 9
8,9,18,19,20,21
Prior to dilution; temperature after dilution is approximately
200°C (400°F).
Does not include fugitive dust emissions escaping control
systems.
4-48
-------
B. Blast Furnace:
Process - The blast furnace reduces the lead and removes
undesirable impurities by formation of a slag. The result-
ing metal, called bullion, assays 94 to 98 percent lead
and must be further treated before it is considered refined
lead. Figure 4-9 shows a typical blast furnace.
OFF-GAS
BUSTLE
PIPE
TUYERES
BLAST AIR
WATER JACKET
HEARTH OR CRUCIBLE
LEAD BULLION
MATTE'
Figure 4-9. Lead blast furnace.
4-49
-------
Controlled air is blasted through side-mounted tuyeres
into the charge to promote formation of metallic oxides.
Some of the metallic impurities and fluxes form a slag
composed predominately of iron and calcium silicates. Most
of the metallic oxides are reduced in the presence of coke
and carbon monoxide.
Three types of blast furnaces are used in the domestic
industry. The conventional blast furnace is a water-jacketed
shaft 4.9 to 7.3 m (16 to 24 ft) high and 3.7 to 6.1 m (12
to 20 ft) long; capacities range from 454 to 910 Mg (500 to
1000 tons) per day of charge. The Australian step jacket
type is 7.60 m long and 10.40 m high (25 ft x 34 ft) and
handles from 725 to 910 Mg (800 to 1000 tons) per day of
charge. One smelter uses a Port-Pierre blast furnace with a
11 14
capacity of 345 Mg (380 tons) per day of charge. '
The charge to the blast furnace includes sinter, coke,
slags from dressing and refining processes, silica, limerock,
and baghouse dusts. About 80 percent of the charge consists
of sinter, which contains 28 to 50 percent lead, the higher
percentages in sinter derived from the high-grade Missouri
concentrates.
Emissions - The lead blast furnace is another major source
of atmospheric emissions from primary lead smelters. Table
4-6 presents characteristics of exhaust gas from this
4-50
-------
Table 4-6. CHARACTERISTICS OF UNCONTROLLED, UNDILUTED
EXHAUST GAS FROM A LEAD BLAST FURNACE
Parameters
Gas flow rate
Temperature
Moisture
content
Grain loading
Particle size
distribution
Lead content
of particulate
SO- content
CO content
Emission factoi
0 particulate
0 lead
Standard
international
units
0.63 mVs-Mg'h"1
product
595-705°C
< 1% v
2-25 g/m3
0.03 ym - 0.3 ym
(majority)
10-40% w
0.01-0.25% v
25-50% v
a
"S
87-125 g/kg Pb
produced
8.7-50 g/kg Pb
produced
English
units
1200 scfm/tph
product
1100-1300°F
< 1% v
1-11 gr/scf
0. 03 ym - 0.3 ym
(majority)
10-40% w
0.01-0.25% v
25-50% v
175-250 Ib/ton
Pb produced
17.5-100 Ib/ton
Pb produced
References
10
8, 17
17
8
8
12
8, 17
8
8,17,20,21
8, 17
Does not include fugitive emissions escaping control systems,
4-51
-------
process. Most of the sulfur originally contained in the
lead concentrate is removed during sintering. S02 emissions
from the lead furnace are approximately 0.01 to 0.25 percent
8 17
by volume. ' Because of the reducing atmosphere, carbon
Q
monoxide in the exhaust gas is 25 to 50 percent by volume.
Because of the high CO content, the exhaust gases require
dilution to 9 to 15 times their volume to oxidize the CO to
CO2 and cool the gas to about 205°C (400°F).10 The CO
content of the diluted gas stream is about 2 percent by
8 17
volume. ' Mass particulate emissions are apparently
unaffected by the type of blast furnace employed. The
extremely small particle sizes reported result from conden-
sation of volatile metal and oxide fumes.
Lead content of the particulate emissions ranges from
12
10 to 40 percent by weight. A lead emission factor,- de-
veloped on the basis of a particulate emission factor of 87
to 125 g/kg of lead product (175 to 250 Ib/ton), is esti-
mated at 8.7 to 50 g/kg (17.5 to 100 lb/ ton).8'17'20'21
These estimates do not include fugitive emissions.
C. Dross Reverberatory Furnace;
Process - Dross is the solid scum removed during the dross-
ing process, amounting to 10 to 35 percent of the bullion.
It contains many of the impurities found in bullion from the
blast furnace such as copper, antimony, bismuth, arsenic,
and lead. Lead typically constitutes 90 percent of the
dross. The function of the dross reverberatory process is
4-52
-------
to remove this lead as a bullion and return it to the dross-
ing process. This process is important for economical
pyrometallurgical production of lead.
The dross reverberatory furnace is similar in construc-
tion to the reverberatory furnace used in copper smelting,
but is smaller. A typical capacity is approximately 130 Mg
of charge (140 tons) per day.
Dross from the dressing process is the major input
material. Fluxes such as silica, limerock, pig iron, and
soda ash may be added. Sulfur, coke, and dusts collected by
fabric filters are also part of the charge. The approximate
lead content of the charge is 60 to 70 percent by weight. ' '
Emissions - The dross reverberatory process is a source of
atmospheric lead emissions. Table 4-7 gives characteristics
of exhaust qas from this process. Sulfur dioxide content of
8 T7
this gas stream is usually below 0.05 percent by volume. '
There are considerable CO emissions due to the reducing
atmosphere of the reverberatory furnace and the coke content
of the charge. Although the literature gives no data con-
cerning the size distribution of particulate emissions, they
are believed to contain largely submicron-sized particles
because of the temperatures incurred and the volatility of many
of the components of the dross.
The lead content of the particulate emissions ranges
22 23
from 13 to 35 percent by weight. ' On the basis of
4-53
-------
Table 4-7. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM A LEAD DROSS REVERBERATORY
Parameters
Gas flow rate
Temperature
Moisture
content
Grain loading
Particle size
distribution
Lead content
of particulate
Emission
factors3
0 particulate
0 lead
SO_ emissions
Standard
international
units
0.31 mVm-Mg-h'1
product
760-980°C
Negligible
0.9-10 g/m3
largely < 1 ym
13-35% w
10 g/kg Pb
produced
1.3-3.5 g/kg
Pb produced
< 0.05% v
English
units
600 scfm/tph
product
1400-1800°F
Negligible
0.4-4.4 gr/scf
largely < 1 ym
13-35% w
20 Ib/ton Pb
produced
2.6-7 Ib/ton
Pb produced
< 0.05% v
References
1
17
17
8
see text
22, 23
8, 17
8, 17
Does not include fugitive emissions.
4-54
-------
a particulate emission factor of 10 g/kg lead product (20
Ib/ton) a lead emission factor is calculated as 1.3 to 3.5
g/kg of lead product (2.6 to 7.0 Ib/ton). '17 These esti-
mates do not include fugitive dust emissions.
74
4.3.2.2 Fugitive Dust
Potential process fugitive emissions for primary lead
smelters are shown in Figure 4-10 process flow diagram. The
various types and sources of fugitive emissions are encircled
and numbered. Some of the fugitive sources, along with the
amounts of particulate and lead uncontrolled emissions, are
shown in Tables 4-8 and 4-8a. The major causes of fugitive
particulate emissions are sintering operations, lead ore
concentrate handling and transfer, and zinc fuming furnace
vents.
Table 4-8. ESTIMATES OF FUGITIVE DUST EMISSIONS
24
FROM OPERATIONS AT ONE PRIMARY LEAD SMELTER
Process
Ore concentrate storage
Return sinter transfer
Sinter sizes and storage
Sinter product dump area
Blast furnace roof vents
Blast furnace upset
Lead casting roof ducts
Zinc fuming furnace area
% by wt.
Lead
f " ' :
37 , '
19 , ' '
58 • '-
31 ., 1
47 ,
27 , -i
38 •'''
3 . < 'I
Uncontrolled
Particulate Emissions
g/kg
0.16
2.25-6.75
0.28-1.22
0.0025-0.0075
0.04-0.12
3.5-11.5
0.22-0.66
1.15-3.45
Ib/ton
0.33
4.5-13.5
0.55-2.45
0.005-0.015
0.09-0.23
7.0-23.0
0.43-1.3
2.3-6.9
4-55
-------
Table 4-8a. ESTIMATES OF FUGITIVE DUST EMISSIONS FROM
OPERATIONS AT TWO PRIMARY LEAD SMELTERS25
I
(Jl
Process
TT
Sinter building
*
Blast furnace
Ore storage
Sinter building
Blast furnace
Dross reverberatory building
Zinc fuming building
Zinc furnace
% Weight
Lead
35
51
47
10
12
22
10
9
Uncontrolled
Emissions (g/Kg)
0.11
0.06
0.015
.0.205
0.205
0.05
0.025
0.055
Parti cul ate
Ib/ton
0.22
0.12
0.3
0.41
0.41
1.0
0.05
0.11
Data for one smelter - remaining data from other smelter
-------
I
Ul
£LAG AND DUST
DUST TO
STORAGE
PILE
BLAST
FURNACE
•Q (T}
MATTE
I TO VTM'INC
.1 PTrjVATF
OR DUMP
TO ORE BEDS
TO COPPER
PLANT
Figure 4-10. Process flow diagram for primary lead smelting showing potential
industrial process fugitive particulate emission points.
-------
Though no data are available on the fugitive size
distribution, Table 4-9 shows the size distribution of flue
dust from an updraft sintering machine effluent. There may
be some resemblance between flue dust and fugitive dust.
Table 4-9
PARTICLE SIZE DISTRIBUTION OF FLUE DUST
FROM UPDRAFT PRIMARY LEAD SINTERING MACHINE
Particle Size ( ^m)
20-40
10-20
5-10
<5
Percent by Weight
15-45
9-30
4-19
1-10
Particle fugitive emissions from the blast furnace
consist basically of lead oxides, 92 percent of which are
n /-
less than 4gn in size.
Information concerning fugitive particulate emission
from lead dross reverberatory is unavailable; however, the
following data for uncontrolled exhaust gas is presented
since it may closely parallel fugitive emission character-
istics. Particulates are largely less than 1 ^n diameter,
with lead content of 13-35 percent by weight. Exit tem-
2 7
peratures are 760-980°C (1400-1800°F).
4-58
-------
Control techniques for fugitive particulate and lead
emissions consist of wet suppression or enclosure for the
storage, handling, and transfer of raw materials, and better
control of operating parameters for the sinter operation,
reverberatory furnace, and blast furnace.
A more detailed account of particulate fugitive emission
factors for primary lead smelters is available in the draft
24
EPA Guidelines for Fugitive Emissions.
4.3.2.3 Control Techniques
A. Contact Sulfuric Acid Plants: Contact sulfuric acid
plants provide one means of SO^ control for sintering and
blast furnaces. Because most particulate matter has the
adverse effect of deactivating the catalyst used to convert
S02 to SOo, complete removal of particulates is required
prior to an acid plant. If complete removal is not achieved,
the absorbing acid will entrap any remaining particulates
and the exhaust gases will contain no particulate lead
13
emissions. Figure 4-11 illustrates the material flow
through an acid plant.
Concentrated SCU gas streams are generally amenable to
contact acid production. Three U. S. smelters operate acid
plants and practice gas separation; a fourth smelter is
planning to construct an acid plant. The weak SO^ gas
stream from these smelters joins the blast furnace gases for
treatment in baghouses. New source performance standards,
however, are based on recirculating the weak SC^ stream and
4-59
-------
i
Ch
o
,
GAS CLEANING 1
1
S02-BEARING GAS |
1
i
1
ELECTROSTATIC .
PRECIPITATOR |
OR BAGHOUSE
1
DUSI ,
1
1
COOLING ELECTRO- |
AND STATIC
SCRUBBING MIST 1
FACILITIES PRECIP- 1
ITATOR ,
WEAK
AN
SOL
1
1
1
1
1
1
ACID 1
DS 1
ACID PRODUCTION
TO ATMOSPHERE
r
rtl-
i I
t
/ING
WER
i
J 1
1
1
L_
L-*
HEAT
EX-
CHANGERS
«--^
"*- ->-
CONVERTER
o
o
«t
as
&
98% ACID
93% ACID
SINGLE CONTACT
DOUBLE'CONTACT
TO ATMOSPHERE
4
FIRST
ABSORPTION
TOWER
SECOND
ABSORPTION
TOWER
J
93% ACID
98% ACID
Figure 4-11. Sulfuric acid plant installed on a primary lead smelter.
-------
treating the entire sinter machine effluent in an acid
plant. Strong SCv gas streams represent 25 to 60 percent of
the total gas volume exiting from a sintering machine.
B. Wet Collectors: Gas cooling, humidification, and secondary
removal of submicron particles are accomplished with wet
scrubbers when acid plants are used to control SC^. High-
energy scrubbers of the venturi type are constructed of 316-
stainless steel.
High-energy wet scrubbers collect and remove particulate
matter by means of water sprays. A high velocity is imparted
to the gas stream while it is injected with water to cause
more turbulence and liquid-solid contact. Collection
efficiencies up to 99.5 percent are achieved with pressure
i Q
drops of 15 kPa (60 in. H2
-------
are treated in fabric filters. Sometimes several fabric
filters are placed in parallel to handle combined gases from
several processes. The blast furnace gases are usually
combined with dross reverberatory exhaust and also, if an
acid plant is present with the weak stream from the sintering
machine. Single gas streams from the sintering machines
that are not recirculated are treated by a separate baghouse
because of the high volume. Only one smelter operates an
ESP for this gas stream. Baghouses usually can achieve
efficiencies of 99 percent or higher on these applications.
The fabric materials impose a maximum temperature
limitation of 285°C (545°F).19 There is also a minimum
temperature limitation of 130 to 140°C (265 to 285°F) due to
19
the acid dew point. The temperature of the gases at the
baghouse inlet is usually maintained at designated levels by
use of waste heat boilers, spray chambers, or dilution air.
Fabric filters usually consist of tubular bags made of
woven synethetic fiber or fiberglass. The particles are
removed from the gas stream by the impact and filtering
action of the fibers. The dust retained on the bags is
periodically shaken loose and collected in hoppers below the
bags.
Fabric filters operate at a pressure drop from 0.3 to
1.5 kPa (1 to 6 in. tUO). The amount of filter area re-
quired is determined by the recommended superficial filter
19
velocity of 0.8 to 1.5 cm/s (1.5 to 3.0 fpm).
4-62
-------
The blast furnace and dross reverberatory furnace
baghouse at a primary lead smelter in Glover, Missouri, was
tested. The smelter has a design capacity of 81,800 metric
tons (90,000 tons) of lead per year.
The blast furnace is an Australian step jacket design
with a nominal capacity of 273 megagrams (300 tons) of
lead bullion per day. The furnace is 7.6 meters (8.3 yards)
long, 1.5 meters (1.64 yards) wide at the lower tuyeres, and
3.0 meters (3.28 yards) wide at the upper tuyeres. A blower
Q
provides up to 510 cubic meters per minute (18,000 ft /min)
2 2
of air at 0.26 kg/cm (0.76 Ib/in ) pressure to the furnace.
The top of the furnace, where charging takes place and
effluent gases are ducted to the control system, is of
typical thimble-top design.
Charge materials for the furnace consist of coarse
sinter, iron, coke, and caustic skims. Charging usually
occurs 17-18 times per shift. Effluent gases from the blast
furnace, swivel vibrator (transfer of sinter to storage
bins), Ross classifying rolls, dross kettles, Roy tapper,
slag granulator, lead tap, slag taps and feed hopper drop
points are exhausted to the blast furnace baghouse control
system. The baghouse control system consists of a humidify-
ing chamber, fresh air inlet, lime addition system, and a
baghouse.
The ASARCO-designed baghouse is enclosed in a concrete
structure containing 6 compartments and is of the pressure
4-63
-------
type. Each compartment contains 204 wool bags. The inlet
3
flow rate to the baghouse is 3710 m /min (131,000 acfm) at
58.3°C (137°F). Lime is added between the water spray
chamber and the baghouse to aid in the collection efficiency
and to retard ignition of the collected dust.
The filter bags are cleaned by mechanical vibration.
The compartment dampers remain closed for approximately 20
seconds after cleaning to allow particulates to settle.
Compartments are cleaned on a rotation basis when the pres-
sure drop across the baghouse exceeds 0.8 kPa (3 in. W.G.).
Table 4-10 shows the results of the testing and indicates
fabric filter performance on blast and dross reverberatory
furnaces.
D. Electrostatic Precipitators: One primary lead smelter
uses an electrostatic precipitator (ESP) on its single
sintering exhaust gas stream. Careful operation of a well-
designed ESP can yield efficiencies exceeding 99 percent,
but measured efficiencies may be considerably lower. ''
Electrical resistivity of the particles, especially
lead oxide particles, must be considered in evaluating
precipitator performance. Resistivity of lead dusts usually
exceeds the maximum 10 ohm-cm designed for electrostatic
precipitation. Increasing the amount of gas conditioning
agents, such as moisture or sulfur trioxide, decreases
. . 28
resistivity.
Efficiency of the ESP decreases dramatically with
4-64
-------
particles smaller than 1 to 2 urn diameter, a size that
corresponds remarkably well with the vast majority of sub-
limed particles. Lead and particulate collection efficien-
cies may not be the same. Nonuniform gas flows also reduce
ESP efficiency. Gas velocities at the electrode plates
should range from 0.9 to 4.6 m/s (3 to 15 fps). Inlet tem-
peratures lower than 232°C (450°F) reduce the efficiency of
high-temperature ESP's; temperatures above 450°C (840°F)
cause volatilization of some metallic oxides and salts in the
19
gas stream and may damage components of the ESP-
4-65
-------
Table 4-10. PERFORMANCE OF BLAST FURNACE AND DROSS
REVERBERATORY FURNACE BAGHOUSE7
I
Ol
CTl
Run
Lead production rate,
Mg/h (tons/hr)
Stack effluent:
Total flow rate, dscm/min.
(dscfm)
Temperature, °C (°F)
Particulate emissions:
mg/dscm (gr/dscf)
mg/m3 (gr/acf)
kg/hr (Ib/hr)
kg/Mg of product
1
12.6 (13.9)
3970 (139,000)
56.2 (159)
38.9 (0.0170)
31.8 (0.0139)
9.17 (20.2)
0.73 (1.60)
2
12.5 (13.8)
4480 (154,000)
63.7 (172)
18.4 (0.00807)
15.3 (0.00671)
4.86 (10.7)
0.39 (0.86)
3
12.5 (13.8)
4240 (146,000)
64.2 (173)
40.4 (0.0177)
33.3 (0.0146)
10.1 (22.3)
0.81 (1.78)
Average
12.5 (13.8)
4230 (146,000)
61.4 (168)
32.1 (0.0141)
26.5 (0.0116)
8.04 (17.7)
0.64 (1.42)
-------
4.3.2.4 Control Costs - The model plant cost analysis is
based on an average-sized, 90,700 Mg/yr (10 TPY) primary
lead smelter. Two separate control systems are evaluated -
one system for the sintering operation and one for the blast
and reverberatory furnaces. Sintering control costs include
only weak-stream control.
A. Sintering - The capacity of the sintering operation
is sufficient to produce enough sinter for the total plant
to produce 13.6 Mg/h (15 tph) of lead product. The opera-
tion generates 48.9 m3/s at 650°C (103,000 acfm at 1200°F)
and emits 3550 kg/h (7800 Ib/hr) of uncontrolled particulate
matter, with up to 65 percent lead by weight. These gases
(weak-stream only) enter a balloon flue to collect large
particles. A spray chamber cools the gases from 540°C to
200°C (1000°F to 400°F) before they enter an insulated
fabric filter. The fabric filter is a mechanical shaker-
type designed to handle a flow rate of 31.6 m /s at 200°C
(67,000 acfm at 400°F) for a filtering velocity of 1 cm/s (2
fpm). The 80-hp fan system is rated at 31.6 m /s (67,000
acfm) at a system pressure drop of 1.1 kPa (4.5 in. W.G.).
Capital costs are estimated at $1.57 million, including
the fabric filter, insulation, balloon flue, spray chamber,
fan system, and ductwork.
Annualized costs are estimated at $482,000, including
utilities, maintenance, labor, overhead, and fixed costs
See Section 2.9 and Appendix B for discussion of cost analyses.
Detailed cost studies are available from EPA upon request.
4-67
-------
(with capital recovery). The collected dust Is recycled
through the process; however, no credit .is applied against
the annual costs. Annual operating time is assumed at 5760
hours. Total annual labor hours is assumed to be 2880
hours.
The capital and annualized costs are expressed below in
terms of exhaust volume and annual labor hours:
S.I, units
Capital, $ = 1.53 x 105V°'6
Annualized, $ = 339V + 19.6H + 3.98 x 104V°*6
V = m3/s at 650°C
H = annual labor hours
16 < V < 150
range
English units
Capital, $ = 1.54 x 103 Q°'6
Annualized, $ = 0.16Q + 19.6H + 402Q0*6
Q = acfm at 1200°F
H = annual labor hours
34,000 < Q < 310,000
range
B. Blast and Reverberatory Furnace - The blast furnace
and dross reverberatory furnaces produce 1?.6 Mg/h (15 tph)
of lead product. The bla-'t furnace rr^nsrateF 8.. 5 std. m /s
-------
exhaust gases at 1200°C (18,000 scfm at 2200°F). The gases
are diluted with ambient air to 100 m3/s at 200°C (211,000
acfm at 400°F). This stream combines with the dross reverbera-
tory gases. The reverberatory furnace generates 4.2 std.
m /s at 815°C10 (9000 scfm at 1500°F) exhaust gas which is
cooled to 200°C (400°F) by a spray tower. The combined
gases, containing 1820 kg/h (4000 Ib/hr) particulate, enter
an insulated mechanical shaker fabric filter which is design-
ed to handle 110 m3/s at 200°F (232,000 acfm at 400°F) at a
filter velocity of 1 cm/s (2 fpm). The lead content of the
particulate ranges from 20 to 40 percent. The 400-hp fan
system provides adequate suction at a system pressure loss
of 1.1 kPa (4.5 in. W.G.). This system is capable of meeting
a typical state particulate emission regulation of about 12
kg/hr (25 Ib/hr).
Capital costs are estimated at $2.91 million, including
fabric filter, insulation, spray tower, fan system, and
ductwork.
Annualized costs are estimated at $993,000, including
utilities, labor, maintenance, overhead, and fixed costs
(with capital recovery). Collected dust is recycled through
the process. Annual operating time is assumed at 8000
hours. Total annual labor hours is assumed to be 4200.
Capital and annualized costs are expressed below in
terms of combined exhaust volume and annual labor hours:
See Section 2.9 and Appendix B for discussion of cost analyses
Detailed cost studies are available from EPA upon request.
4-69
-------
S.I, units
Capital, $ = 1.74 x 105V°'6
Annualized, $ = 178V + 19.6H + 4.54 x 104V°'6
V = m3/s at 200°C
H = annual labor hours
34 < V < 330
range
English units
Capital, $ = 1760 Q°'6
Annualized, $ = 0.084Q + 19.6H + 459Q0'6
Q = acfm at 400°F
H = annual labor hours
80,000 < Q < 700,000
range
4-70
-------
4.3.2.5 Impacts
A. Emission Reduction Benefits
Based on the fabric filter system serving the model
plant sintering machine and blast/reverberatory furnaces, a
400 kg/Mg (800 Ib/ton) reduction in particulate emissions is
estimated. The lead content of the sintering system catch
is 65 percent, and 20 to 40 percent of the blast/reverb
system.
B. Energy Impact
For the model processes it is estimated that air pollu-
tion control to achieve SIP limits would require about 0.18
GJ/Mg (0.18 MM Btu/ton) of lead product. The total process
29
energy required is 19.2 GJ/Mg (19.2 MM Btu/ton) of product.
Therefore, about 1 percent increase in energy consumption is
expected.
C. Water Pollution Impact
Wet collectors are never used on these processes.
Little or no wastewater is generated in the fabric filter
and ESP applications. Therefore, no impact on water pollu-
tion can be attributed to lead control.
D. Solid Waste Impact
Dusts collected by fabric filters and ESP's are re-
cycled. Therefore, no solid waste impact will occur.
4-71
-------
4.3.3 Primary Zinc Production
Estimated production of primary slab zinc in 1975 was
397 Gg (438,000 tons). Estimated zinc consumption was 837
Gg (925,000 tons). The difference between primary production
and consumption was made up by imports of 344 Gg (380,000
tons), secondary redistilled slab zinc production of 52.4 Gg
(58,000 tons), and reduction in stocks. ° The 1975 lead
emissions from primary zinc production were about 112 Mg
(124 tons). Zinc smelters are in operation at 6 locations.
4.3.3.1 Process and Emissions - A flow diagram illustrating
primary zinc production is given in Figure 4-12. Ore con-
centrate from a mill is first roasted to remove sulfur. The
lead content of zinc concentrates varies widely. One plant
has reported concentrations of 0.30 to 0.50 percent lead,
but at other plants the lead content may run as high as 2 to
5 percent. The amount of lead subsequently released to
the atmosphere is highly dependent on initial ore concen-
tration. The waste gas stream from roasting is used as feed
to a sulfuric acid plant. The roasted product is further
processed by pyrometallurgical or electrolytic methods. The
first step in pyrometallurgical processing is sintering,
4-72
-------
CONCENTRATION
ROAST
ACID
LEACH
SINTER
PURIFI-
CATION
RETORT
ELECTRO-
LYSIS
ACID
PLANT
Figure 4-12. Flow diagram of primary zinc production,
4-73
-------
which prepares the roasted calcine for introduction into a
retort furnace, where it is reduced to zinc metal. Three
types of retorts are in use at primary zinc smelters -
horizontal, vertical, and electrothermic.
In electrolytic processing, the roasted concentrate is
first leached in sulfuric acid to dissolve the zinc, then
purified by various filtration and precipitation steps
before recovery of metallic zinc by electrolysis.
No estimates are given for particulate emissions from
electrothermic retorting, although the total emissions from
the only zinc plant using such furnaces are much lower than
those from the other types of retorts. During the roasting
stage, modified Nichols-Herreshoff furnaces are used for
deleading, eliminating 90 to 95 percent of the lead.
Because virtually all of the remaining lead is removed
during sintering, lead emissions from electrothermic retorts
are thought to be negligible.
The only significant sources of particulate and lead
emissions are sintering and horizontal and vertical retort-
ing. At all smelters, the off-gas from roasting is used as
feed to a sulfuric acid plant after preliminary cleaning in
cyclones and electrostatic precipitators. Atmospheric lead
emissions from acid production are negligible. The lead
which is volatized during roasting ends up in the residues
from the gas cleaning and acid manufacturing phases.
4-74
-------
Electrolysis does not cause significant atmospheric emis-
sions of particulate or lead. The use of electrolyte covers
and additives to control misting allows only negligible lead
emissions from this process.
Six primary zinc plants were operating in the U. S. at
the end of 1975, with a total annual production capacity of
590 Gg (652,000 tons). Three of the plants (58 percent of
total caoacity) are nvrometallurgical and three are elec-
trolytic. The 1975 primary zinc production was only about
66 percent of installed capacity.
A. Sintering:
Process - Sintering volatilizes lead and cadmium impurities
and creates a hard, porous mass suitable for introduction
into the retort. Dwight-Lloyd sintering machines are used
at primary zinc smelters. These are downdraft machines
using bar or grate-type pallets which are joined to form a
continuous metal conveyor system. The roasted concentrate
is distrubuted and ignited on the pallets along with re-
recled sinter product, coke or oil, sand, and other ingred-
ients. The machines operate at atmospheric pressure at a
temperature of 1040°C (1900°F).S Figure 4-13 depicts a
typical downdraft sinter machine. The largest U. S. primary
o
pyrometallurgical smelter operates nine sinter machines.
Emissions - Table 4-11 presents selected exhaust gas para-
meters for sinter machines. In addition to lead, the parti-
4-75
-------
PAN CONVEYOR TO
SIZING SYSTEM
HOOD
t
SINTER IVUX
IGNITION FURNACE • <
WINDBOXES
\ [7- SWING SPOUT
PALLETS
TO COTTRELLS
WINDBOXES
TflACK
Figure 4-13. Downdraft sinter machine.7
CONDENSER
Figure 4-14. Horizontal retort.
4-76
-------
Table 4-11. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM A ZINC SINTER MACHINE
Parameters
Gas flow rate
Temperature
Grain loading
Particle size
distribution
Lead content
of particulate
S02 emissions
Dew point
Emission
factors
0 particulate
0 lead
Standard
international
units
I. 2-2. 7 mVs-Mg-h-1
product
95-370°C
0.9-10.3 g/m3
100% < 10 ym
30-55% w
4.5-7% v
50-60°C
45 g/kg product
13.5-25 g/kg
product
English
units
2300-5200
scfm/tph product
200-700°F
0.4-4.5 gr/scf
100% < 10 ym
30-55% w
4.5-7% v
122-140°F
90 Ib/ton
product
27-50 Ib/ton
product
References
8, 33
8, 34
8
8
8
8
8
35
4-77
-------
culates are composed of 5 to 25 percent zinc, 2 to 15
q
percent cadmium, and 8 to 13 percent sulfur. All of the
particulates are less than 10 ym in size. The lead content
of particulate following control is taken as 10 percent,
35
based on values of 11 percent in the literature and 9
percent measured in emissions at one smelter. The lead
content of the particulate before control has been reported
q
to range from 30 to 55 percent by weight.
Total lead emissions from sintering are shown in Table
4-12 based on estimated 1975 production levels and emission
factors from the literature. A total of 84 Mg (93 tons) of
lead was released from sinter machines at primary zinc
smelters.
Table 4-12. LEAD EMISSIONS AT ZINC SINTER MACHINES
Type of plant
Electro thermic
retort
Horizontal
retort
Vertical
retort
Estimated 1975
zinc production,
Gg
141
28
64
(1000 tons)
(156)
(31)
(71)
Lead emission
factor,7 »35
g/kg
0.28
0.33
0.54
(Ib/ton)
(0.56)
(0.66)
(1.10)
Lead
emissions,
Mg
40
9
35
(tons)
(44)
(10)
(39)
4-78
-------
B. Retorting:
Process - Horizontal retorting is the oldest process now
in use for reducing calcine to zinc metal. The furnace
consists of a series of tubular refractory receptacles
placed horizontally within an enclosure, with the retort
face exposed to the atmosphere. A condenser is placed over
the retort face. Firing is external, achieved by passing
combustion products through the areas between the retorts.
The temperature inside the retort reaches 1200°C (2200°F).
Figure 4-14 is a diagram of a typical horizontal retort.
The National Zinc Company plant, the only facility using
this process, operates 5824 horizontal retorts with a total
7
capacity of 127 Mg (140 tons) per day of zinc product.
This plant is being replaced by an electrolytic plant of
about the same capacity.
The vertical retort is also externally fired. The
charge passes downward through a central shaft and is
expelled from the bottom of the furnace. Molten zinc is
condensed from the vapor created by reduction of the charge.
38
Operating temperature is 1315°C (2400°F). Figure 4-15 is
a diagram of a vertical retort. The New Jersey Zinc Co.
plant, the only facility using this reduction process,
operates 43 vertical retorts with a total capacity of 286 Mg
(315 tons) of zinc product per day.
4-79
-------
VENT
GAS
SCRUBBED CLEAN GAS
RETURNED
CHARGE
SPLASH CONDENSER!
TO CASTING
AND REFINING
TO STACK
CHARGE COLUMN
NATURAL GAS
HEAT
RECUPERATOR
Figure 4-15. Vertical retort.
4-80
-------
Table 4-13. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
Parameters
Gas flow rate
Grain loading
Lead content
of particulate
CO? content
Emission
factors
0 particulate
0 lead
Standard
international
units
3.6-5.7 n^/s-Mq-rf1
product
0.10-0.32 g/m3
0-3% w
12-17% v
40 g/kg
1.2 g/kg
English
units
7000-11,000
scfm/tph product
0.04-0.13 gr/scf
0-3% w
12-17% v
80 Ib/ton
2.4 Ib/ton
References
8
8
8
8
35
4-81
-------
Emissions - Available data on uncontrolled emissions from
horizontal and vertical retorts are shown in Tables 4-13 and
4-14. Total emissions for 1975 from primary zinc retorts,
as shown in Table 4-15, are based upon estimated production
levels and published emission factors. There were no controls
at the only operating horizontal retort, and an overall
collection efficiency of 92 percent was assumed for the
vertical retort. Total lead emissions from retorting are
estimated to be 28 Mg (31 tons).
r\ i
4.3.3.2 Fugitive Emissions - A process flow diagram for
primary zinc production with potential fugitive particulate
emission sources is shown in Figure 4-16. The various types
and sources of potential fugitive emissions are numbered and
encircled. Some of those fugitive emission sources for
primary zinc retorting are shown in Table 4-16 with the
relative magnitude of the uncontrolled particulate emissions.
Lead content will be about the same as ore concentrate for
ore handling and storage emissions.
Major sources of fugitive emissions are zinc ore handling
and transfer, zinc casting, retort building and sinter
machine discharge and screens, but data concerning the fugi-
tive emissions from primary zinc production are unavailable.
Data characterizing the flue gases are available and may
closely parallel the characteristics of fugitive emissions.
Flue gas particulate emissions from sinter machines are less
than 10ym in size and generally contain between 30-35 percent
4-82
-------
Table 4-14. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM A VERTICAL ZINC RETORT
Parameters
Gas flow rate
Temperature
Grain loading
Particle size
distribution
Lead content
of particulate
C02 content
Emission
factors
0 particulate
0 lead
Standard
international
units
6.4m /s-Mg-h
product
590°C
2 . 1 g/m
100% < 10 ym
4-5% w
2.5-3.0% v
50 g/kg
product
2-2.5 g/kg
product
English
units
12,300 acfm/tph
product
1100°F
0.9 gr/scf
100% < 10 ym
4-5% w
2.5-3.0% v
100 Ib/ton
product
4-5 Ib/ton
product
References
8
8
8
8
8
35
4-83
-------
CONCENTRATED •
f ZnS
I ORE
CONCENTRATE x
f
ISTORAGE "
\, _<
-------
Table 4-15. LEAD EMISSIONS FROM ZINC RETORTS
OO
CJ1
Plant
Horizontal
retort
Vertical
retort
Estimated 1975
zinc production.
Gg
28
64
(1000 tons)
(31)
(71)
Particulate
emissions ,33
Mg
1130
3220
(tons)
(1250)
(3550)
Average percent
lead content.
of emissions"
1.5%
4.5%
Uncontrolled
lead emissions.
Mg
17
145
(tons)
(19)
(160)
Lead emissions
after controls,.
Mg
17
11
(tons)
(19)
(12)
Does not include electrothermic retorts
-------
Table 4-16. FUGITIVE LEAD EMISSION SOURCES AND
ESTIMATED UNCONTROLLED PARTICULATE EMISSION FACTORS
24
i
CO
cr\
1. Zinc ore unloading
2. Zinc ore storage
3. Zinc ore handling &
transfer
4. Sinter machine windbox
5. Sinter machine discharge
& screens
6. Retort furnace residue
discharge & cooling
7. Retort furnace upset
0.015-0.2 g/kg
unloaded
0.17 g/kg stored
0.82-2.5 g/kg
handled
0.12-1.22 g/kg
sinter
0.28-1.22 g/kg
sinter
0.25-1.02 g/kg Zn
2.5-5 g/kg zinc
0.03-0.4 Ib/ton
0.33 Ib/ton
1.64-5.0 Ib/ton
0.25-1.1 Ib/ton
0.55-2.45 Ib/ton
0.50-2.0 Ib/ton
5-10 Ib/ton
-------
by weight lead. Flue gas particulates from retort buildings
range from the micron to submicron size and normally have 0-
3 percent lead by weight.
Control of the fugitive emissions from primary zinc
production include proper operating procedures for the
sinter machine windbox, and the proper operational procedures
or use of movable hoods for the zinc retort furnace. The
hoods evacuate the buildings to a fabric filter to capture
the fugitive emissions.
4.3.3.3 Control Techniques
A. Gas Removal; Combustion gases in a sintering machine
are drawn down through the machine by windboxes operating at
a suction of 3.5 to 4.5 kPa (14 to 18 in. H2O).31 Draft
fans draw the gases into the dust collection system. At the
horizontal retort furnace, gas escapes through a small hole
in the stuffing at the mouth of the condensers. No effective
particulate control system has been developed for horizontal
retorts. Because each of the thousands of retorts is an
7
emission source, a massive control system would be required.
Gas from the vertical retorts is drawn through the liquid
zinc condensers by venturi scrubbers. Off-gas exits through
a vent at the top of the furnace.
B. Gas Cooling: The sinter gas is cooled to 50 to 60°C
(120 to 140°F) by water atomized at a pressure of 3 MPa (30
atm.) in a large conditioning chamber. In addition, this
4-87
-------
process lowers the electrical resistance of the gas. Air
dilution is also used to cool the gas from sinter machines,
as well as from vertical retorts.
C. Precleaning: Settling flues are used to remove large
31 _. .
particulate from sinter machines at one smelter. It is
not known whether any other precleaning treatment is used at
sinter machines or vertical retorts, although cyclones are
probably used at the latter.
D. Electrostatic Precipitators: ESP's are used to control
particulate emissions, including lead, from sinter machines
at primary zinc plants. Horizontal-flow, plate-type ESP's
are most common. Particulate is removed from the plates by
vibrators or rappers. At one plant, each of three precipi-
tators is rated at 47.2 m3/s (100,000 scfm). Mild-steel
construction is common. Typical spark rates range from 50
to 250 sparks/minute. The corona power generally ranges
from 0.12 to 0.18 w/m -s"1 (0.2 to 0.3 w/cfm).33 Precipi-
tators may incorporate up to four sections to reduce down-
time. Temperature and moisture content of the gas must be
carefully controlled to ensure efficient operation. The
inlet gas temperature should be between 120° and 260°C (250
and 500°F). Operation at a lower temperature will cause
condensation in the precipitator, and at a higher tempera-
ture may warp the plates. Other causes of poor performance
of ESP's include nonuniform gas distribution, abnormal
4- 88
-------
electrical conditions, improper rapping, and gas leakage
39
causing reentrainment of the particulates.
E. Fabric Filters; Fabric filters are used to clean the
gases from vertical retort furnaces. At one sinter machine
a fabric filter is used in parallel with three ESP's.
Reverse-air jet cleaning is used most commonly. Tie pressure
drop for fabric filters used in nonferrous metals production
ranges from 0.5 to 2.0 kPa (2-8 in. H20). Too low a
pressure drop prevents proper inflation of the bag, result-
ing in improper cleaning action, whereas too high a drop
increases the friction and wear between the blow ring and
bag. The average air flow, or air-cloth ratio, ranges from
1.0 to 1.8 cm3-s~1/cm2 of cloth (2.0-3.5 cfm/ft2). The
3 —1 2 2
ratio increases to 4.6 cm -s /cm (9.0 cfm/ft ) during
33
cleaning with a reverse-air jet stream. The most critical
operating variables are moisture content and temperature of
the gas. The temperature must be 10° to 24°C (50° to 75°F)
above the dew point to prevent condensation. Too much
moisture causes formation of mud cakes on the bags, creating
P
high resistance and ultimate rupture. Dacron or woven
glass are popular fabrics in this type of filter. Normal
operating temperature for Dacron bags is 130°C (270°F).
The maximum filtering velocity for these fabrics is 4.1 cm/s
28
(8 fpm).
4-89
-------
4.3.3.4 Control Costs - A primary zinc smelter with a pro-
duction capacity of 327 Mg/day (360 TPD) zinc product is
chosen for the model plant cost analysis. Two separate con-
trol systems are evaluated - one for sintering operations
and one for vertical retorting.
A. Sintering - A sintering operation of adequate size
to feed the 327 Mg/day (360 TPD) zinc plant exhausts 85 m /s
of gas at 650°C (179,000 acfm at 1200°F) and emits particu-
late matter at the rate of 614 kg/h (1350 Ib/hr), of which
30 to 55 percent is lead. The gases enter a balloon flue to
settle out large particles. The gases enter a spray chamber
at 540°C (1000°F) to reduce the temperature to 315°C (600°F)
and increase humidity, prior to entering an electrostatic
precipitator. The ESP is designed to maintain an efficiency
of about 95 percent by providing a total plate area of 2470
m (26,600 ft ). The inlet flow rate is 63 m3/s (133,000
acfm). A 300-hp fan system is rated at 63 m /s (133,000
acfm) at a total system pressure drop of 2.1 kPa (8.5 in.
W.G.). This control system is adequate to meet the average
state emission limitation of 9.1 kg/h (20 Ib/hr).
Tho capital costs for the above system are estimated at
$2.97 million, including balloon flue, spray chamber, ESP,
fan system, hold tank, pump, and ductwork.3
The annualized costs are estimated at $855,000, in-
cluding utilities, labor, maintenance, overhead, and fixed
See Section 2.9 and Appendix B for discussion of cost analyses
Detailed cost studies are available from EPA upon request.
4-90
-------
costs (with capital recovery). Collected solids are re-
cycled through the process. Annual operating time of 8000
hours and 4000 annual labor hours are assumed.
The capital and annualized costs are expressed below in
terms of exhaust flow rate and annual labor hours:
S.I, units
Capital, $ = 2.07 x 105V°'6
Annualized, $ = 1230V + 46,900V0'6 + 19.6H
V = m3/s at 650°C
H = annual labor hours
28 < V < 260
range
English units
Capital, $ = 2094Q0'6
Annualized, $ = 0.58Q + 474Q0*6 + 19.6H
Q = acfm at 1200°F
H = annual labor hours
60,000 < Q < 540,000
range
B. Vertical Retorting - A vertical retorting operation
for a 327 Mg/day (360 TPD) zinc smelter exhausts 87 m /s at
590°C8 (185,000 acfm at 1100°F) and emits 680 kg/h (1500
Ib/hr) of uncontrolled particulate, of which 4 to 5 percent
is lead. The gases enter a balloon flue where large particles
4-91
-------
are settled out. The gases are cooled from 480°C (900°F) to
about 150°C (300°F) by a spray chamber designed to handle 75
m3/s (161,000 acfm). The gases enter a reverse-air fabric
filter designed to clean 42 m3/s (90,000 acfm) at a filter
velocity of 1.3 cm/s (2.5 fpm) .33 A 250-hp fan system
provides adequate service for a system pressure drop of 1.3
kPa (5 in. W.G.). This system is capable of meeting state
emission regulations of 11 kg/h (25 Ib/hr).
Capital costs for the above control system are esti-
mated at $1.94 million, including balloon flue, spray
chambers, fabric filter, fan system, hold tank, pump, and
ductwork.
Annualized costs are estimated at $661,000, including
utilities, maintenance, labor, overhead, and fixed costs
(with capital recovery). Collected solids are recycled
through the process; no credit for the recycled dust is
applied against annual costs. Annual operating time is
estimated at 8000 hours and annual labor requirements are
4000 hours.
The capital and annualized costs are expressed below in
terms of exhaust volume and annual labor hours:
S.I, units
Capital, $ = 1.33 x 105V°'6
Annualized, $ = 890V + 34,600V°'6 + 19.6H
See Section 2.9 and Appendix B for discussion of cost analyses,
Detailed cost studies are available from EPA upon request.
4-92
-------
V = m3/s at 590°C
H = annual labor hours
30 < V < 260
range
English units
Capital, $ = 1340 Q0'6
Annualized, $ = 0.42Q + 350Q0*6 + 19.6H
Q = acfm at 1100°F
H = annual labor hours
60,000 < Q < 560,000
range
4-93
-------
4.3.3.5 Impacts
A. Emission Reduction Benefits
Particulate emissions from the sintering and vertical
retort processes can be reduced by a total of 95 kg/Mg (190
Ib/ton) of zinc product. Lead content of the sintering dust
is 30 to 55 percent while that of the vertical retort is 4
to 5 percent.
B. Energy Impact
The energy required to operate the entire primary
sine industry averaged 55.2 GJ/Mg (55.2 MM Btu/ton) of
09
zinc product. Additional energy required to operate the
sintering ESP and the vertical retort fabric filter for the
model processes (Section 4.3.3.4) is estimated at 0.15 GJ/Mg
(0.15 MM Btu/ton) corresponding to an increase of only 0.3
percent. Therefore, no significant energy impact can be
expected for air pollution control in the zinc industry.
C. Water Pollution Impact
Wet collectors are not used on the sintering or the
retorting operations. No wastewater is generated by the
fabric filters and ESP's, and therefore, no water pollution
impact is expected.
D. Solid Waste Impact
No solid wastes are generated since they are recycled
through the plant. Therefore, no solid waste impact by air
pollution control equipment anticipated.
4-94
-------
4.3.4 Primary Copper Production
In 1975 approximately 5 Tg (5.5 x 10 tons) of copper
concentrate was treated to produce about 1.25 Tg of copper
metal (1.38 x 10 tons). In the same year, the primary
copper industry emitted about 1314 Mg of lead (1444 tons) to
the atmosphere at 15 locations. These totals do not include
fugitive emissions.
4.3.4.1 Processes and Emissions - The primary copper
industry is engaged in concentrating the copper ore of
various minerals and processing it to copper by pyrometal-
lurgical or hydrometallurgical methods. At present, most of
the domestic copper is produced by pyrometallurgy and a
small portion by hydrometallurgy. Hydrometallurgy is a wet
process causing negligible air pollution. The pyrometal-
lurgical processes are the main source of air pollution. As
shown in Figure 4-17, primary copper production involves
mining, concentrating, and smelting processes.
Depending upon the physical properties of the ore, the
concentrating process generally involves crushing, grinding,
classification, flotation, and dewatering. All of these
operations are carried out at ambient conditions. Lead
emissions from ore crushing and grinding are discussed in
Section 4.3.1. There are minor lead emissions from flo-
tation and dewatering.
4-95
-------
STACK
FUEL
ai*s
Figure 4-17. Primary copper smelter flow diagram.
-------
Roasting, calcining, and converting processes are the
main sources of air pollution in the industry. Currently
electrostatic precipitators are used on most of the roasters,
reverberatory furnaces, and converters of the primary domestic
copper industry. Materials handling is also a source of
particulate emissions.
A. Roasting:
Process - The ore concentrate is charged directly to the
roaster to produce a charge containing controlled amounts of
sulfur as needed for economical smelting and conversion.
Roasting dries the concentrate and volatilizes some impurities,
About 1 Mg (1.1 tons) of the concentrate is treated with
addition of 150 kg fluxes (330 Ib) and 740 kg of air (1630
Ib) to produce 900 kg of calcined product (1980 Ib).7
In the roasting of copper sulfide ores the concentrates
are heated in air (or oxygen-enriched air) to the temperature
required for removing some of the sulfur as sulfur oxides.
Two types of roasters are currently being used: multiple-
hearth and fluid-bed, as illustrated in Figures 4-18 and 4-
19. Seven of the fifteen U. S. copper smelters operate
roasters: four are multiple-hearth and three are fluid-bed.
The remaining facilities feed concentrate directly to the
reverberatory furnace without roasting.
Since the basic design of a multiple-hearth roaster
results in a relatively long contact time for roasting
concentrate, these units generally operate at relatively
4-97
-------
OFF-GAS
RABBLE ARM
RABBLE BLADE
CALCINE
TO
HOT AIR
EXHAUST
CALCINE
COOLING AIR
Figure 4-18. Multiple-hearth
4-98
-------
OFF-GAS
SLURRY
FEED
TUYERE
HEADS
PRODUCT
Figure 4-19. Fluid-bed roaster,
4-99
-------
lower throughput rates. The turbulent bed in a fluid-bed
roaster provides for extremely intimate contact between the
concentrates and oxidizing environment. On the basis of
average copper-roasting applications in the United States,
one multiple-hearth roaster is used to roast approximately
170 Mg per day (190 tpd) of copper concentrate, and one
fluid-bed roaster is used to roast about 1.04 Gg per day
(1150 tpd). Operation of fluid-bed roasters generally is
autogenous in that no fuel is required other than that
needed for preheating of the roaster for start-up. Operation
of multiple-hearth roasters may or may not be autogenous.
Roaster temperatures range from 200°C (390°F) at the top of
the hearth to 760°C (1400°F) on the lower levels.41
Emissions - Dusts, oxides of sulfur, and water vapor are
released during roasting. The off-gases from multiple-
hearth roasters contain S02 in the range of 0.5 to 2 percent.
The off-gases from fluid-bed roasters, however, contain S0~
in the range of 12 to 14 percent.
The roasting process generates particulate emissions on
the order of 22.5g/kg of ore concentrate charged (45 Ib/ton)34
as shown in Table 4-17. According to one report, the lead
content of the combined flue dust ranges from 0.5 to 12
percent. It is assumed that 0.5 percent corresponds to a
concentrate of 1000 ppm lead and the 12 percent corresponds
to a concentrate of 24,000 ppm lead, Therefore, the lead
emission factor for the roasting process is determined to be
1.2 (P) g/kg (2.3 (P) Ib/ton) of concentrate charged, where
4-100
-------
Table 4-17. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM A COPPER ROASTER
Parameters
Gas flow rate
Temperature
Grain loading
Particle size
distribution
Lead content
of particulate
SO- content
Emission
factors
0 particulate
0 lead
Standard
international
units
0.73 (x) + 1.6a
650°C
14-55 g/m3
15% < 10 ym
85% > 10 ym
0.5-12% w
0.5-2% v
(multiple hearth)
12-14% v
(fluid bed)
22.5 g/kg
1.2 P g/kgc
English
units
1.4(y)+ 3.4b
1200°F
6-24 gr/scf
15% < 10 ym
85% > 10 ym
0.5-12% w
0.5-2% v
(multiple heart*
12-14% v
(fluid bed)
45 Ib/ton
2.3 P lb/tonc
References
42
42
34
43
44
42
i)
34
x = Mg/hr production capacity; expression yields exhaust
flow in m^/s.
y = TPH production capacity; expression yields exhaust
flow in 1Q3 scfm.
P is the percent of lead in the concentrate.
4-101
-------
P is the percentage of lead in the concentrate.
Based on the average lead content for U. S. copper
concentrates of 0.3 percent40 and an overall control efficiency
of 92.6 percent, the total lead emissions from copper roasting
facilities in 1975 are estimated at 107 Mg (117 tons) by the
throughput of 4.0 Tg (4.4 x 10 tons) of concentrate.
B. Smelting Furnaces:
Process - The roasted product (calcine) is smelted in the
reverberatory furnace to produce copper-iron sulfide matte
and a silicious slag. Smelting can be done in a reverberatory
furnace or an electric furnace, as shown in Figures 4-20 and
4-21. All but two domestic smelters use fossil-fuel-fired
reverberatory furnaces; the other two use electric furnaces.
An average of 580 Mg (640 tons) per day of copper calcine
and concentrates is smelted in each of 26 operational rever-
beratory furnaces. At one electric furnace, approximately
225 Mg'(250 tons) per day of copper calcine is processed.
The roasted charge is fed to the furnace through a
hopper and is combined with fuel and hot air. The charge
contains copper concentrate or roasted product, recycled
copper precipitates, converter slag, flue dust, and flux.
When the concentrate is charged directly to the electric
furnace, the feed must be dried ahead of the furnace to
reduce moisture content. The liquid matte is formed at
about 980 C (1800°F), and the furnace temperature may reach
1315 C (2400 F), One Mg of concentrate (1.1 ton) produces
about 0.67 Mg of copper matte (0.73 ton) and 0.8 Mg of slag
(0.88 ton).
4-102
-------
CALCINE
FETTLING DRAG
CONVEYOR
OFF-GAS
FUEL ,
x
CONVERTER
SLAG
SLAG
AIR
AND OXYGEN
BURNERS-1
MATTE
FETTLING PIPES
Figure 4-20. Reverberatory furnace.
4-103
-------
FETTLING PIPES
°FF-GAS
ELECTRODES
ELECTRIC POWER |\ f
CONVERTER
SLAG LAUNDER
CALCINE
Figure 4-21. Electric smelting furnace.
4-104
-------
Emissions; About 15 kg of particulate is emitted per Mg of
47
copper matte produced (30 Ib/ton). This is equivalent to
10 kg of particulate per Mg of copper concentrate charged
(20 Ib/ton). When the process is controlled, the flue dust
from the control device is recirculated to the charge. Lead
content of the particulate depends on the input material
(wet concentrate or calcine) and volatility of lead at the
process temperature, which varies from plant to plant. At
one plant, where concentrates are directly fed to the
furnace, the reverberatory furnace particulate emissions
48
contained an average of 8.3 percent lead. At this average
lead content of dust, the lead emission factor is 0.83 g/kg of
concentrate (1.66 Ib/ton). This data is from a green feed
smelter; however, calcine fed furnaces may have less lead.
Table 4-18 presents the emission characteristics of the
reverberatory furnace.
Lead is also present in amounts of 100 ppm in rever-
49
beratory furnace slag and 250 ppm in electric furnace slag.
With typical control efficiencies of electrostatic
precipitators, one study developed a controlled lead emis-
sion factor of 0.044 g/kg of concentrate (0.088 Ib/ton) for
a reverberatory furnace. ' The total lead emitted to the
atmosphere by smelting in 1975 was 220 Mg (242 tons).
Fugitive dust emissions from the smelting processes may
contribute significantly to the total lead emissions. Quanti-
tative information on fugitive emissions from the smelting
process is not available.
4-105
-------
Table 4-18. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM A COPPER REVERBERATORY FURNACE
Parameters
Gas flow rate
Temperature0
Moisture
content
Grain loading
Particle size
distribution
Lead content
of particulate
(green feed)
S02 content
Emission
factors
0 particulate
0 lead
(green feed)
Standard
international
units
0.73 x + 1.6a
370°C
18% v
5-12 g/m3
8.3% w
0.5-2.5% v
10 g/kg Cu
concentrate
0.8 g/kg Cu
concentrate
English
units
1.4y + 3.4b
700°F
18% v
2-5 gr/scf
8.3% w
0.5-2.5% v
20 Ib/ton Cu
concentrate
1 . 7 Ib/ton Cu
concentrate
References
42
43
51
42
42
51
47
x = Mg/h product. Expression yields flow in m3/s.
y = tph product. Expression yields flow in 103 scfm.
Temperature of the air after passing through the waste heat
boiler prior to being diluted with air.
4-106
-------
C. Converting:
Process - The copper matte is treated batchwise in a con-
verter to produce blister copper. Figure 4-22 shows a
converter. The molten matte is brought in ladles from the
reverberatory or electric furnace and charged to the con-
verter. Residues from zinc plants, dusts from other pro-
cesses, scrap, and siliceous ore are also added. Air from
dryers is forced into the molten bath or matte. The re-
action is carried out at 1200°C (2200°F). Blister copper
and slag are formed. The slag is skimmed off and the metal
is transferred to holding furnaces for casting or further
refining. During the reaction, the sulfur in the charge is
converted SO- which escapes in the exit gases. The lead
and other trace elements are partly oxidized and volatilized.
The copper converting process is autogenous. An average
converter processes approximately 270 Mg of copper matte per
day (300 tpd).7
Emissions - The converter emits about 120 g particulate/kg
of copper (240 Ib/ton), which is equivalent to 30 g/kg of
concentrate (60 Ib/ton). Lead content of particulate is
variable, depending mainly on the lead content of the con-
verter charge. At one plant, particulate from the conver-
52
ter contained 0.83 weight percent lead; and at another
48
plant the particulate contained 8.6 percent by weight.
4-107
-------
OFF-GAS
TUYERE PIPES
PNEUMATIC
PUNCHERS
SILICEOUS
FLUX
FLUX GUN
AIR
AIR
Figure 4-22. Copper converter.7
4-108
-------
At 8.6 percent lead content, the uncontrolled lead
emission factor is 2.6 g/kg of concentrate (5.2 Ib/ton).
According to one source the factors for uncontrolled and
controlled lead emission are 2.5 g/kg of concentrate (5
Ib/ton) and 0.3 g/kg of concentrate (0.6 Ib/ton), respec-
tively. ' These emission factors are based on the
particulate emission factor, the lead content of the uncon-
trolled particulate, and lead content of particulate exiting
from the ESP. At 92 percent lead control efficiency and 2.6
g/kg concentrate (5.2 Ib/ton) of uncontrolled lead emissions,
the lead released to the atmosphere from this source in 1975
was 987 Mg (1085 tons). Table 4-19 presents typical charac-
teristics of emissions from the converter.
D. Refining:
Process - Copper from the converter is processed by fire-
refining and electrolytic refining. Although some domestic
copper is produced as fire-refined commercial copper, about
90 percent of total production is electrolytic copper.
Fire-refining produces copper anodes and is usually followed
by electrolytic refining to produce the final copper product.
Fire-refining is usually done in cylindrical furnaces to produce
anodes or in small reverberatory furnaces to produce salable
copper. Molten copper from the converter or occasionally
cold blister copper, air, fluxes (soda ash or lime), and a
reducing agent are the inputs to the process.
4-109
-------
Table 4-19. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM A COPPER CONVERTER
Parameters
Gas flow rate
Temperature
Moisture
content
Grain loading
Particle size
distribution
Lead content
of particulate
S02 content
Emission
factors
° particulates
0 lead
Standard
international
units
0.83-1.0 m3/s-Mg-h~
product
1200°C
4.8-6.8%
12 g/m3
50% < 10 ym
0.83-8.6% w
6-7% v
120 g/kg Cu
produced
1.0-10 g/kg Cu
English
units
1600-2000
scfm/tph produc
2200°F
4.8-6.8%
5.3 gr/scf
50% < 10 ym
0.83-8.6% w
6-7% v
240 Ib/ton Cu
produced
2.0-21 Ib/ton C
i
References
42
t
43
53
43
48, 52
33
u
4-110
-------
In fire-refining the molten metal is oxidized by
blowing air into the charge with agitation. The slag that
is formed is skimmed from the products and returned to the
converter. At the completion of oxidation, the reduction
phase of fire refining is accomplished either by a process
called poling (inserting logs into the smelt) or by intro-
ducing natural gas into the furnace. Fluxing is performed
only in production of fire-refined salable products. The
product from the furnace is poured at 1120°C (2050°F) into
molds.
In electrolytic refining the anodes are dissolved in an
electrolyte containing copper sulfate and sulfuric acid.
Impurities are removed as slimes. The copper cathodes are
subsequently melted and cast into commercial shapes.
The fire refining process emits about 5 g of parti-
culate/kg of concentrate charged (10 Ib/ton). No data are
available on the composition of particulate. The slimes
from the refining contain 2 to 15 percent lead.
4-111
-------
Table 4-20. UNCONTROLLED PARTICULATE FUGITIVE EMISSIONS
24
CONTAINING LEAD FROM COPPER SMELTING OPERATIONS
Process
Uncontrolled particulate
emissions
1. Unloading & handling of
concentrate
2. Ore concentrate storage
3. Roaster operations
4. Reverb operations
5. Converter operation
5 g/kg handled 10 Ib/ton
0.17 g/kg stored 0.33 Ib/ton
11 g/kg Cu 23 Ib/ton
4.2 g/kg Cu 8.5 Ib/ton
1.6-8.9 g/kg Cu 3.3-18 Ib/ton
0 /
4.3.4.2 Fugitive Emissions - Figure 4-23 shows a process
flow diagram for primary copper production with the potential
fugitive particulate emission in dotted lines. The various
types and sources of potential fugitive emissions are numbered
and encircled. Several of the sources of fugitive emissions
are shown in Table 4-20, with the relative magnitude of the
uncontrolled emission rates. Major sources of fugitive
emissions are ore concentrate unloading, roaster operations,
and converter operations.
Lead contents will be approximately equivalent to the
ore concentration for ore handling and storage, and the same
as furnace stack emission for furnace fugitive emissions.
The chemical characteristics of fugitive particulate emissions
from the various primary copper operations are shown in
Table 4-21. Fifteen percent of the particulates in the
4-112
-------
RAILCAR f ^- ORE
J CONCEN-
VTJ W TRATES
STORAGE
(252 Cu)
SILICA *•; ROASTER •'* CALCINE N
FLUXES
[F REQUIRED) FLUE DUST-,
| COPPER PRECIPITATES - *•
FUEL FLUX-J
, ^RlSr™ ELE£
COPPER (>99.5Z Cu) ^
LIME- ^ RAILCAR
STONE
FLUX <~ ' ^
AND
SILICA
STORAGE
Y ® ©
t ! _
' (^ ~ ' 6^
.^CONVERTER*-.. /
KEVERBERATORY ^ CONVERTER "•
FURNACE MATTE fc
(SMELTER) X, (35% Cu) .*
®*?^~\ T i "^
®' T -f f
ti • x-^ SILICA Al". AND oo
T * (20) FLUX OR OXYGEN S
AIR FUEL fi§r i ENRICHED g
SLAG i i 8
E-
**•.
FIRE
ROLTTIC REFINING ,
I.1ING ^ FURNACE ^
ANi TAP t /«JODE FURNACE) A
f u «%• UT)
ANODE ANODE AIR
MUD "* CASTING OTHERS
TMPURITIES; FLUX NATTrRAT. fE.G.. GREE
, _^ __ _^»
'"" '"' ' ~ (IF REQUIRLU; GAS LtXIS^)
Figure 4-23. Process flow diagram for primary copper smelting
showing potential industrial process fugitive emission points.
-------
Table 4-21. CHEMICAL CHARACTERISTICS OF FUGITIVE PARTICULATE EMISSIONS
FROM VARIOUS PROCESS STEPS IN PRIMARY COPPER SMELTING55
*>.
I
Process Step
Ore Concentrate Storage
and Handling
Limestone Storage and
Handling
Slag Handling
Roaster Loading and
Operation
Reverberatory Furnace
Loading and Operation
Matte Transfer
Converter Loading
and Blowing
Composition (Percent)
Cu
28
0.5
5
5
42
1
Fe
24
40
32
S
32
1.5
25
sio2
11
38
1
CaO
~ 60
Zn
16
16
8
Cd
4
Pb
0.3
0.3-
18
0.4-
18
0.25
2-6
Other
5
40
20
0.5
0.5
-------
exhaust gas are If??'?, than 10 UP. ;mr 85 percent are greater
than 10urn in diameter Lead content of the rarticulate
is less than 18 percent by weight Hood systems with baghouses
can be used to control reverberatory slag, metal tapping
operations and converter loading. The slag pile emissions
are currently uncontrolled, but partial hoods and fume vents
through fabric filters or scrubbers could be used.
4.3.4.3 Control Techniques - At ore concentrating units,
the exhaust ventilation system is equipped with dust collectors
to control effluents from the ore crushers. Roaster off-
gases are commonly controlled with fabric filters or combined
with reverberatory furnace exhaust and passed through an
ESP. Converting operations are primary controlled by ESP's.
Particulate control devices on slime recovery furnaces are
generally limited to small ESP's or scrubbers.
A. Roasting Facilities: The same emission control equipment
is used with fluid-bed and multiple-hearth roasters. Of the
seven roaster facilities now operating, three facilities
combine the roaster gases with reverberatory gases prior to
7
treatment. At the remaining facilities, the particulates
are recovered with combinations of several control devices.
After preliminary solids collectxon, the gas from either type
roaster is cooled to about 315°C (600°F) by water sprays or
heat exchangers before final cleaning. At one facility, the
-------
roaster gases are passed through a settling (balloon) flue,
where the gas velocity is reduced sufficiently to allow the
heavier particles to drop out. Dust collected in the flue
is recycled to the reverberatory furnace. Collection efficiency
of a balloon flue system can range from 30 to 60 percent.
At one facility, the roaster gas is treated by an ESP before
joining reverberatory furnace gases. At two other facilities
the exhaust is passed through cyclones and ESP's before joining
the converter gases. Efficiencies of the cyclone collectors
are 80 to 85 percent. With careful conditioning of the flue
gases, efficiencies of the ESP's can exceed 99 percent.
A fabric filter for collection of fine particulate can
achieve efficiencies of 99 percent or more. These filters
have not been used on roaster effluents because of the
corrosive nature of exit gases and the temperature limitation
of 285 C (545 F). However, since early 1976, Anaconda Copper
has been successfully operating a baghouse on off-gases from
a fluid bed roaster, electric furnace, and reverberatory
furnaces. Recently, the reverberatory furnaces have been
shut down.
4-116
-------
B. Reverberatory Furnace: Most smelter operators practice
gas cooling of reverberatory and converter gases. The gases
are cooled by noncontact heat exchangers in waste heat
boilers, conductive cooling ducts, or cooling chambers.
The reverberatory furnace gases are treated in ESP's in
combination with other control equipment such as balloon
flues and cyclones for particulate control. At some plants,
the roaster gases are added to the reverberatory furnace
gases before treatment. Both hot and cold ESP's are in use
at the copper smelters. Usually the gas temperature is
reduced to about 370°C (700°F) for treatment in hot ESP's or
the gas temperature is further reduced to 115 to 260°C (240
to 500°F), usually by dilution and water sprays, for treat-
ment in cold ESP's.
Table 4-22 indicates the ESP performance of two gas streams
from separate roaster/reverberatory furnaces which enter
ESP's.
4-117
-------
Table 4-22. ESP PERFORMANCE ON COPPER REVERBERATORY
53
FURNACE AND ROASTER COMBINED EXHAUST GAS STREAMS
Parameter
Flow rate, m /s
10 acfm
Temperature, °C
OF
Grain loading, g/m
gr/scf
Mass rate, kg/h
Ib/hr
ESP 1
outlet
288
610
80
176
0.04
0.094
176
387
ESP 2
outlet
294
623
83
181
0.057
0.13
241
531
C. Converter; Converter gases are treated with equipment
similar to that used for reverberatory furnace gases, i.e.,
a settling flue in combination with hot or cold ESP's.
Particulate removal efficiencies of the ESP's at copper
smelters range from 91 percent to 98.5 percent. Control
efficiencies of the ESP's for collection of lead and other
elements range between 90 and 98 percent, comparable to the
overall mass collection efficiency. At one plant, the gases
enter the ESP at 125°C (256°F). Surface area of the ESP is
approximately 0.067 m /m -s"1 (1.230 ft2/scfm) of flue
52
gas. Most converter gas streams enter sulfuric acid
plants, a practice that practically eliminates particulate
discharges.
4-118
-------
Table 4-23 indicates ESP performance on two separate
copper converter operations.
Table 4-23. ESP PERFORMANCE ON TWO COPPER CONVERTER OPERATIONS53
Parameter
Flow rate, m /S
103 acfm
Temperature, °C
oF
Grain loading, g/m
gr/dscf
Mass rate, kg/h
Ib/hr
Converter A
Inlet
62
132
124
256
0.63
1.44
527
1160
Outlet
96
204
101
214
0.11
0.26
158
347
Converter B
Inlet
86
183
121
250
0.78
1.8
900
1980
Outlet
95
.201
136
277
0.065
0.15
81.8
180
4-119
-------
4.3.4.4 Control Costs - A medium-sized copper smelter with
a capacity of 174 Mg/day (192 TPD) is considered the typical
model plant to determine control costs. Two separate con-
trol systems are evaluated.
A. Roaster/Reverberatory Furnace - The roaster and
reverberatory furnace exhausts are controlled by a common
ESP system. The roaster exhaust volume is 55 m /s at 425°C
(116,000 acfm at 800°F) after 50 percent air dilution.
Reverberatory gases are cooled from 1200°C (2200°F) to 370°C
(700°F) by a waste heat boiler. After 50 percent air dilu-
tion, reverberatory furnace gases amount to 55 m /s at 240°C
(116,000 acfm at 470°F), which combine with the roaster
stream. The combined stream, containing 270 kg/hr (600
Ib/hr) particulate, enters a cyclone system which is designed
to handle 102 m /s at 330°C (217,000 acfm at 630°F) and
assumed to operate at 1.4 kPa (6 in. W.G.) pressure drop and
80 percent efficiency. The precleaned stream enters an
insulated electrostatic precipitator at 315°C (600°F) with
2 2
7720 m (83,100 ft ) of plate area, yielding 99.6 percent
efficiency, sufficient to meet state standards.57 A 665-hp
fan system handles 100 m3/s (211,000 acfm) at a total system
pressure drop of 3 kPa (12 in. W.G.).
Capital costs are estimated at $5.0 million for the
roaster/reverb control system.3 These costs included the
ESP, cyclone system, waste heat boiler, I.D. fan system, and
ductwork.
See Section 2.9 and Appendix B for discussion of cost
analyses. Detailed cost studies are available from EPA
upon request.
4-120
-------
Annualized costs are estimated at $1.54 million, in-
cluding utilities, labor, maintenance, overhead, and fixed
costs (with capital recovery). Annual operating time of
8000 hours and annual labor time of 8000 hours are assumed,
Collected dust is recycled through the process.
Capital and annualized costs are expressed below in
terms of combined exhaust volume and annual labor hours:
S.I, units
Capital, $ = 3.1 x 105V°'6
Annualized, $ = 2440V + 19.6H + 70,600V0'6
V = m3/s at 330°C
H = annual labor hours
30 < V < 300
range
English units
Capital, $ = 3140Q0*6
Annualized, $ = 1.15Q + 19.6H + 713Q0*6
Q = acfm at 630°F
H = annual labor hours
70,000 < Q <630,000
range
B. Converter - The converter operations in the "model
plant have a material throughput rate of about 7.3 Mg/h (8.0
tph). The exhaust hood captures 34.6 m /s at 1200°C (73,300
4-121
-------
acfm at 2200°F). Emissions are estimated at 870 kg/h (1920
Ib/hr) particulate, of which up to 9 percent is lead. The
temperature is reduced to 370°C (700°F) by a waste heat
boiler before the gases enter a balloon flue which collects
large particles. The gases enter a spray chamber to reduce
the volume to 15.2 m3/s at 315°C (32,200 acfm at 600°F)
before they enter an insulated electrostatic precipitator.
2
The ESP is a dry mechanical-rapping type with 1450 m
2
(15,600 ft ) of plate area to maintain an efficiency of 98
percent.^ The 75-hp fan system is designed to handle 15-2
m /s (32,200 acfm) at a total system pressure drop of 2.1
kPa (8.5 in. W.G.). The system is capable of meeting an
average state limitation of 7.3 kg/h (16 Ib/hr).
Capital costs are estimated at $2.65 million, including
the ESP, waste heat boiler, spray chamber, balloon flue, fan
system, and ductwork.
Annualized costs are estimated at $705,000, including
utilities, labor, maintenance, overhead, and fixed costs
(with capital recovery). Collected dust is largely recycled
through the process ; however,no credit is applied against
the annual costs. Annual operating time is assumed at 8000
hours and annual labor hours is assumed to be 4000.
The capital and annualized costs are expressed below in
terms of exhaust volume and annual labor hours:
See Section 2.9 and Appendix B for discussion of cost analyses,
Detailed cost studies are available from EPA upon request.
4-122
-------
S.I, units
Capital, $ = 3.2 x 105V°'6
Annualized, $ = 722 V + 19.6H + 7.18 x 104V°'6
V = m3/s at 1200°C
H = annual labor hours
10 < V < 100
range
English units
Capital, $ = 3.2 x 103 Q°'6
Annualized, $ = 0.341Q + 19.6H + 725Q0'6
Q = acfm at 2200°F
H = annual labor hours
22,000 < Q < 220,000
range
4.3.5 Impacts
A. Emission Reduction Benefits
Application of SIP control on the model roaster/rever-
beratory and converter operations (Section 4.3.5) reduce
particulate emissions by 150 kg/Mg (300 Ib/ton) of copper
product.
On the roaster/reverberatory system the ESP reduces
emissions by 37 kg/Mg (75 Ib/ton) of copper product. The
lead content ranges from 4 to 11 percent. The converter ESP
reduces emissions by 120 kg/Mg (240 Ib/ton) of copper pro-
duct, containing 0.83 to 8.3 percent lead.
4-123
-------
B. Energy Impact
The processes in a copper smelting facility require a
total of about 33 GJ/Mg (36 MM Btu/ton) without air pollu-
tion control.29 The ESP's serving the roaster/reverberatory
and the converter model operations (Section 4.3.3.3) consume
29
as estimated 0.46 GJ/Mg (0.5 MM Btu/ton) of copper produced,
corresponding to 1.5 percent increase in energy consumption.
C. Water Pollution Impact
Small amounts of water are used in the ESP but this
does not constitute a major source of wastewater. Therefore
no impact on water pollution can be expected by the use of
ESP's.
D. Solid Waste Impact
Solid wastes generated by the reverberatory furnace
alone is about 3 Mg/Mg copper product (3 ton/ton). Solid
wastes generated by other processes are not estimated
because of lack of data.
The amount of dry solid waste generated by air pollu-
tion control devices designed to achieve SIP control levels
will be about 150 kg/Mg (300 Ib/ton) of copper product,
corresponding to a 5 percent increase. Converter ESP wastes
may contain 0.8 to 8.3 percent lead while roaster/reverbera-
tory ESP dust will contain 4 to 11 percent lead.
4-124
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4.3.6 References for Section 4.3
1. Communications with Mr. J. Patrick Ryan. U.S. Bureau
of Mines. Lead-Zinc Branch. Washington, D.C.
September 9, 1976.
2. Wixson, B.C. and Jennett, J.C. The New Lead Belt In
the Forested Ozarks of Missouri. Environmental Science
& Technology- Volume 9. No. 13. December 1975. pp.
1128-33.
3. Development Document for Interim Final and Proposed
Effluent Limitations Guidelines and New Source Perfor-
mance Standards for the Ore Mining and Dressing Indus-
try. Point Source Category. Vol. 1. U.S. EPA.
October 1975.
4. Environmental Assessment of the Domestic Primary
Copper, Lead and Zinc Industry- U.S. EPA. Contract
No. 68-02-1321. Task No. 38. September 1976. Rough
Draft.
5. Handbook of Chemistry and Physics. 32nd Edition.
Editor in Chief. C.D. Hodgman. 1950. pp. 1328-1343.
6. Mineral Industry Surveys. U.S. Department of the
Interior, Bureau of Mines. Washington, D.C. December
18, 1975.
7. Background Information for New Source Performance
Standards: Primary Copper, Zinc, and Lead Smelters.
Volume I. Proposed Standards. Environmental Protec-
tion Agency. Research Triangle Park, North Carolina.
Publication No. EPA-450/2-74-002a. October 1974.
8. Jones, H.R. Pollution Control in the Nonferrous Metals
Industry. Noyes Data Corporation, Park Ridge, New
Jersey. 1972.
9. Duncan, L.J. and E.L. Keitz. Hazardous Particulate
Pollution from Typical Operations in the Primary
Nonferrous Smelting Industry- Presented at 67th
Annual Mfg. of Air Pollution Control Association.
Denver, Colorado. June 9-13, 1974.
4-125
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10. Exhaust Gases from Combustion and Industrial Processes.
U.S. Environmental Protection Agency Technical Center.
Durham, North Carolina. EHSD 71-36. October 1971.
p. VI-32 to VI-44.
11. Personal communication with Regional EPA Offices.
12. Interim Report on Control Techniques for Lead Air
Emissions Development of Lead Emission Factors and
1975 National Lead Emission Inventory. U.S. Environ-
mental Protection Agency. Research Triangle Park,
North Carolina. 68-02-1375. June 18, 1976. 25 p.
13. Kirk-Othmer. Lead in Encyclopedia of Chemical Technology.
New York, Interscience Publishers. John Wiley and Sons,
Inc., 1967.
14. Development Document for Proposed Effluent Limitations
Guidelines and New Source Performance Standards for
the Primary Copper, Lead, and Zinc Segment of the Non-
ferrous Metals Manufacturing Point Source Category
(Draft). U.S. Environmental Protection Agency.
Washington, D.C. Contract No. 68-01-1518. December
1973.
15. Minerals Yearbook. Washington, D.C. U.S. Department
of the Interior. Bureau of Mines. 1973.
16. Development for Interim Final Effluent Limitations,
Guidelines and Proposed New Source Performance Standards
for the Lead Segment of the Nonferrrous Metals Manu-
facturing Point Source Category. Environmental Pro-
tection Agency, EPA 440/1-75/032-a. February 1975.
17. Systems Study for Control of Emissions Primary Non-
ferrous Smelting Industry. Arthur G. McKee and Co. For
U.S. Department of HEW. June 1969.
18. Devitt, T.W. and V. Katari, et al. Trace Pollutant
Emissions from the Processing of Metallic Ores. PEDCo-
Environmental Specialists, Inc. For U.S. Environmental
Protection Agency- Research Triangle Park, North
Carolina. Contract No. 68-02-1321. August 1974.
19. Vandegrift, A.E. (Dr.), L.J. Shannon (Dr.), P.G.
Gorman (Dr.), E.W. Lawless (Dr.), E.E. Sallee, and
M. Reichel. Particulate Pollutant System Study - Mass
Emissions, Volumes 1, 2, and 3. U.S. Environmental
Protection Agency, (NTIS), Durham, North Carolina.
PB-203 128, PB-203 522 and PB-203 521. May 1971. 500 p.
4-126
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20. Shea, E. P. Source Sampling Report. Emissions from
Lead'Smelter. Midwest Research Institute. EPA Contract
No. 68-02-0228. Task No. 17. 1973.
21. Hussy, R. C. Source Testing. Emissions from a Primary
Lead Smelter Blast Furnace. Midwest Research Institute.
EPA Contract No. 68-02-0228. Task No. 10. May 1972.
22. Test No. 73-PLD-l. Emission Measurement Branch, U. S.
Environmental Protection Agency. Research Triangle
Park, North Carolina. Contract No. 68-02-0229.
23. Preferred Standards Path Analysis on Lead Emissions
from Stationary Sources (Draft). Emission Standards
and Engineering Division. U. S. Environmental Protection
Agency. Research Triangle Park, North Carolina.
August 9, 1974.
24. Control Program Guideline for Industrial Process
Fugitive Partieulate Emissions. Preliminary Draft.
PEDCo-Environmental Specialists, Inc. Cincinnati, Ohio.
EPA Contract 68-02-1375. Task No. 33. December 10, 1976.
25. Preliminary Environmental Assessment of Lead Emissions
from Selected Stationary Sources. Final Draft Report.
Midwest Research Institute. EPA Contract 68-02-1399,
Task 5. June 1977.
26. A Study of Fugitive Emissions from Metallurgical
Processes. Midwest Research Institute. Contract No.
68-02-2120. Monthly Progress Report No. 8. Kansas
City, Missouri. March 8, 1976.
27. Environmental Assessment of the Domestic Primary Copper,
Lead and Zinc Industry, Volume I (Draft). PEDCo-Environmental
Specialist, Inc. Contract No. 68-02-1321, Task Order
No. 38. Cincinnati, Ohio. September 1976.
28. Danielson, J. A. (ed.) Air Pollution Engineering Manual.
2nd Edition. Air Pollution Control District. County
of Los Angeles. For U. S. Environmental Protection
Agency Research Triangle Park, North Carolina.
AP-40. May 1973.
29. Fejer, M.E. and D.H. Larson. Study of Industrial Uses of
Energy Relative to Environmental Effects. Institute of
Gas Technology, Chicago, Illinois. For U.S. Environmental
Protection Agency. Research Triangle Park, N.C. Contract
No. 68-02-0643. July 1974.
4-127
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30. U. S. Department of Interior, Bureau of Mines, Commodity
Data Summaries 1976. Washington 1) C. 1976.
31. Lund, R. E. et al. Josephtown Electrothermic Zinc
Smelter of St. Joe Minerals Corporation. In AIME World
Symposium on Mining and Metallurgy of Lead and Zinc,
C. H. Cotterill and J. M. Cigan (eds.) AIME. New York.
1970.
32. Hamilton, W. F. and P A. Boys. Control of Airborne
Emissions - What's the Cost? No. 74-97. U S. Environ-
Mental Protection Agency, Research Triangle Park, North
Carolina. 1974.
33. U.S. Environmental Protection Agency. Field Surveil-
lance and Enforcement Guide for Primary Metallurgical
Industries. EPA 450/3-73-002. Research Triangle Park,
North Carolina. December 1973.
34. Environmental Protection Agency. Compilation of Air
Pollutant Emission Factors. Second Edition. Research
Triangle Park, North Carolina. Publication No. AP-42.
April 1973.
35. Crane, G. B. Control Techniques for Lead Emissions.
Draft. U. S. Environmental Protection Agency. Research
Triangle Park, North Carolina. February 1971.
36. Yost, K. J., et al. The Environmental Flow of Cadmium
and Other Trace Metals. NSF Grant 61-35106. Progress
Report, July 1, 1974 to June 30, 1975. Purdue University.
West Lafayette, Indiana. 1975.
37. Schlechten, A. W. and A. Paul Thompson. Zinc and Zinc
Alloys. In Encyclopedia of Chemical Technology. R. E.
Kirk and D. F. Othmer (eds.). John Wiley and Sons.
New York. 1964.
38. Yost, K. H. et al. The Environmental Flow of Cadmium
and Other Trace Metals. NSF Grant 61-35106. Progress
Report, July 1, 1973 to June 30, 1974. Purdue University.
West Lafayette, Indiana. 1974.
39. Nichols, G. B. (ed.) The Electrostatic Precipitator
Manual. The Mcllvaine Company. Northbrook, Illinois.
1976.
40. Information provided by Schroeder, H. J. Bureau of
Mines. July 1976. Washington, D. C.
41. Bureau of Mines. Control of Sulfur Oxide Emissions in
Copper, Lead, and Zinc Smelting. United States Depart-
ment of the Interior, Washington, D. C Information
Circular 8521. 1971.
4-128
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42. Exhaust Gases from Combustion and Industrial Processes,
Engineering Science, Inc. Washington, D. C. October 2,
1971. Distributed by National Technical Information
Center.
43. Jones, H. R. Pollution Control in the Nonferrous Metals
Industry. Noyes Data Corporation. 1972.
44. Environmental Protection Agency. Industrial Process
Sources. In: Control Techniques for Lead Emissions
(Draft). February 1971.
45. Preferred Standards Path Analysis on Lead Emissions
from Stationary Sources (Draft). Emission Standards
and Engineering Division, Environmental Protection
Agency. Research Triangle Park, North Carolina.
August 9, 1974.
46. Industrial Gas Cleaning Institute, Inc. Air Pollution
Control Technology and Costs. Nine Selected Areas.
Environmental Protection Agency. Contract No. 68-02-0301,
September 1972.
47. Semarau, K. T. Control of Sulfur Oxide Emissions from
Primary Copper, Lead and Zinc Smelters. A Critical
Review. Journal of Air Pollution Control Association.
21: June 1971.
48. Taylor, P. L. Characterization of Copper Smelter Flue
Dust. (For Presentation at the 69th Annual Meeting of
the Air Pollution Control Association). Portland,
Oregon. June 27 - July 1, 1976.
49. Calspan Corporation. Assessment of Industry Hazardous
Waste Practices in Metal Smelting and Refining Industry.
Primary and Secondary Nonferrous Smelting and Refining.
1975.
50. Preferred Standards Path Analysis on Lead Emissions
from Stationary Sources (Draft). Emission Standards
and Engineering Division, Environmental Protection
Agency. Research Triangle Park, North Carolina.
August 9, 1974.
51. Scientific and Technical Assessment Report on Cadmium.
Environmental Protection Agency. Report No. EPA-600/
6-75-003. March 1975.
4-129
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52. Weisenberg, I. J. and J. C. Serne. Compilation and
Analysis of Design and Operating Parameters of the
Phelps Dodge Corporation. New Cornelia Branch Smelter,
Aja, Arizona for Emission Control Studies. Environ-
mental Protection Agency. Contract No. 68-02-1405.
January 1975.
53. Statnick, R. M. Measurement of Sulfur Dioxide Particulate
and Trace Elements in Copper Smelter, Converter and
Roaster/Reverberatory Gas Streams. Environmental
Protection Agency. Publication No. EPA-540/2-74-111.
October 1974.
54. Kirk-Othmer. Copper. In: Encyclopedia of Chemical
Technology. Volume 6. New York. John Wiley and Sons,
Inc. 1968.
55. Shannon, L. J. and P. G. Gorman. Particulate Pollutant
System Study, Volume III - Emission Characteristics.
Midwest Research Institute. Prepared for U. S. Environ-
mental Protection Agency. Contract No. 22-69-104.
1971.
56. Development Document for Interim Final and Proposed
Effluent Limitations Guidelines and New Source Performance
Standard for the Ore Mining and Dressing Industry.
Point Source Category Vol. 1. Environmental Protection
Agency. Washington, D. C. Publication Number EPA/1-75/
032-b. February 1975.
57. Personal communication. Kennecott Copper Co. July 14, 1976.
4-130
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4.4 SECONDARY NON-FERROUS METALS AND ALLOY PRODUCTION
In 1975 an estimated 800 Mg of lead (882 tons) was
emitted by secondary non-ferrous metals production, repre-
senting about 11 percent of all industrial point source lead
emissions. Secondary lead smelting emitted 753 Mg (830
tons), and brass and bronze processes emitted 47 Mg of lead
(52 tons) in 1975/ not including fugitive emissions.
4.4.1 Secondary Lead Smelting
A substantial portion of the lead used in the United
States is produced by secondary smelters. In general, these
smelters produce lead alloys and oxides from used lead
products, primary battery scrap and lead residues. In 1975,
over 548 Gg of lead (604,600 tons) was produced at secondary
smelters resulting in the emission of approximately 753 Mg
of lead (830 tons), not including fugitive emissions.
4.4.1.1 Process Description - While two-thirds of the
output of the secondary lead industry is processed in blast
furnaces or cupolas, some smelting is also done in rever-
beratory furnaces and pot furnaces.
A. Blast Furnaces: Blast furnaces generally produce 18 to
2
73 Mg per day of lead (20-80 tpd). The furnace shown in
Figure 4-24 is a vertical production unit which is charged
through a door near the top while blast air is blown in
through tuyeres near the bottom. The process is semicon-
4-131
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EMISSIONS
TO VENTILATION SYSTEM
3
COOLING TOWERS
COOLING BLEED AIR
i
SLAG 1 1 LEAD
BLAST FURNACE
DUST RECYCLED TO REVERBERATORY FURNACE
Figure 4-24. Blast furnace with typical
2
air pollution control system.
tinuous in that the charge is added over a period of 1 or 2
days and product is withdrawn nearly continuously during
that period. The charge stock consists of oxidized lead
and lead scrap to be reduced, plus coke for combustion,
o
limestone, scrap iron, and rerun slag. Approximately 70
percent of the molten charge material is tapped off as hard
lead (5 to 12 percent antimony). The remainder includes
approximately 18 percent slag and matte, 5 percent water,
and 7 percent dust, which may be discharged. About 5
percent of the slag is retained for rerun later.
B. Reverberatory Furnaces: A reverberatory furnace, as
shown in Figure 4-25 is merely a device for heating the
charge stock by direct contact with the products of combus-
4-132
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EMISSIONS
TO VENTILATION SYSTEM
_r
XX
X\
REVERBERATORY FURNACE
Jpnnn
COOLING TOWERS ' ® SsAGHOUSE
COOLING BLEED AIR>
FAN
DUST RECYCLE
Figure 4-25. Reverberatory furnace with a
2
typical emission control system.
tion of oil and/or gas burners and by radiation from the hot
walls of the furnace. The charges may be a mixture of lead
scrap, battery plates, oxides, drosses, and lead residues.
These are put into the furnace at regular intervals as the
mass of the charge becomes fluid. Ordinarily the furnace is
kept "tight" to limit the infiltration of air in order to
maintain a furnace temperature of 1260°C (2300°F) which
generates exit gases at tenperatures between 650 and 732 C
(1200° and 1350°F).5
The molten metal is tapped off at intervals as a semi-
soft lead. The continuous operation produces about 49 to 59
kg of metal per square meter of hearth area (10 to 12
lb/ft2).
4-133
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A typical reverberatory furnace produces 45 Mg/day of
lead ingot (50 tpd).2 About 47 percent of the charge stock
is recovered as metal, 46 percent is recovered as slag, and
4
7 percent leaves as smoke and fumes.
C. Pot Furnaces; Pot furnaces, as shown in Figure 4-26,
generally produce from 0.9 to 45 Mg of lead per day (1 to 50
tpd) and are used primarily for remelting, alloying, and
refining processes. Operating temperatures are usually 400
to 480°C (750 to 900°F). In general, since pot furnaces are
indirectly fired, their pollution potential is much lower
than that of blast or reverberatory furnaces. During
melting and holding operations, uncontrolled emissions are
low because the vapor pressure of lead is low at the melting
temperature. During dross skimming and refining, however,
2
EMISSIONS
emissions increase substantially.
I
FROM FURNACES
U\J
HOLDING, LEAD MELTING,
AND REFINING POTS
STACK
Jpppr
BAGHOUSE
Figure 4-26. Pot furnaces with typical
2
emission control system.
4-134
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4.4.1.2 Emissions - Temperatures of stack gases from well-
sealed blast furnaces may range from 650 to 732°C (1200 to
4
1350°F). In practice, however, the charge doors of the
furnace are frequently left open or removed to accommodate
additional charge, thereby reducing the temperature of the
exit gases to a range from 204°C to 260°C (400 to 500°F).5
In addition to the particulate matter, which consists
of smoke, oil vapor, fume, and dust, large volumes of carbon
monoxide are produced from partial oxidation of the coke
fuel. Table 4-24 summarizes pertinent emission data for
blast furnaces.
Blast furnaces used for the recovery of secondary lead
are reported to emit approximately 120 g particulate/kg of
metal reclaimed (240 Ib/ton). Source tests of several
furnaces indicate that the average emission factor for
lead is approximately 28 g Pb/kg of lead produced (56
7 fi Q If) 11
lb/ton).'''' This indicates that particulate emis-
sions from lead smelters contain about 23 percent lead.
Particulates emitted by reverberatory furnaces are
nearly spherical, with a distinct tendency to agglomerate.
Particulate emissions from lead reverberatory furnaces are
approximately 113 g/kg of metal charged (225 lb/ton). In
the absence of any definite data, concentrations of lead in
the fumes from reverberatory furnaces are considered to be
the same as those from blast furnaces. This assumption
gives an emission factor of approximately 26.5 g/kg of lead
produced (53 lb/ton). Table 4-25 summarizes the characteristics
4-135
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Table 4-24. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FOR SECONDARY LEAD BLAST FURNACE
Parameters
Gas flow rate
Temperature
Moisture content
Grain loading
Particle size
Lead content
of particulate
Emission factors
0 particulate
0 lead
Standard
international
units
7.3 m3/s-Mg-h~
730°C
5% v
9 g/m3
> 3 ym - 58%
2-3 ym - 23%
1-2 ym - 17%
0-1 ym - 2.3%
23% w
120 g/kg
product
28 g/kg
product
English
units
14,000 scfm/tph
product
1350°F
5% v
4 gr/scf
> 3 ym - 58%
2-3 ym - 23%
1-2 ym - 17%
0-1 ym - 2.3%
23% w
240 Ib/ton
product
56 Ib/ton
product
References
6
5
10
10
7,8,9,10,11
5
of exhaust gas from reverberatory furnaces.
Based on an average lead emission of 27.5 g/kg product
(55 Ib/ton) and an overall control efficiency of 95 percent,
the production of 548 Gg (604,600 tons) caused the emission
of 753 Mg of lead (830 tons) to the atmosphere in 1975, not
including fugitive emissions.
1 O
4.4.1.3 Fugitive Emissions
A process flow diagram for secondary lead smelting with
the potential fugitive emission sources is shown in Figure
4-27. The various sources and types of potential fugitive
emissions are encircled and numbered. Some of those sources
4-136
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Table 4-25. UNCONTROLLED EXHAUST GAS CHARACTERISTICS
FOR SECONDARY LEAD REVERBERATORY FURNACE
Parameters
Gas flow rate
Temperature
Grain loading
Lead content
of particulate
Emission
factors
0 particulate
0 lead
Standard
international
units
1.0 m /s *Mg'h
charge
650-730°C
1.8-9.0 g/m3
23% w
113 g/kg
product
27 g/kg
product
English
units
2200 scfm/tph
charge
1200-1350°F
1-5 gr/scf
23% w
225 Ib/ton
product
53 Ib/ton
product
References
4
5
4, 12
7,8,9,10,11
5
Table 4-26. SECONDARY LEAD SOURCES AND FUGITIVE
PARTICULATE EMISSIONS
Lead and iron scrap burning
Sweating furnace
Reverberatory furnace
Blast furnace
Pot furnace
Casting
0.5-1.0 g/kg scrap
(1.0-2.0 Ib/ton scrap)
0.8-1.75 g/kg charge
(1.6-3.5 Ib/ton)
1.4-7.85 g/kg charge
(2.8-15.7 Ib/ton)
6 g/kg charge
(12 Ib/ton charge)
0.02 g/kg charge
(0.04 Ib/ton)
0.44 g/kg lead cast
(0.88 Ib/ton)
4-137
-------
RAILCAR
U>
CO
BURN CUT
(OF WOOD,
RUBBER, PAPER
AND PLASTICS)
TO SHIPPING
Figure 4-27. Process flow diagram for secondary lead smelting showing
potential industrial process fugitive particlulate emission points.
-------
are listed in Table 4-26 and show the relative magnitude of
uncontrolled particulate fugitive emissions from secondary
lead operations.
Data concerning the characterization of fugitive par-
ticulate emissions from secondary lead smelting operations
are very limited, but stack emission information is available
as an approximation of characteristics of the fugitive
emissions.
Emissions from smelting furnaces range in size from
0.07 to 0.4 ym and have a mean particulate diameter of 0.3 ym.
Emissions from a reverberatory furnace have approximately
the same size characteristics and have a lead content of
about 23 percent by weight.
Lead and iron scrap burning operations are essentially
incinerator processes and thus fugitive emission controls are
the same as for incinerators. Better control of operating
procedures, such as feed rates or keeping charge doors
closed as much as possible, will help alleviate fugitive
emission generation. If it is feasible to be selective in
choosing only the cleaner scrap, the amount or period of
burning time can be reduced and thus result in fewer fugitive
emissions. If old and worn equipment parts are allowing
the escape of emissions, the replacement of these parts may
help reduce fugitive emissions. The increase of the exhaust
rate of the primary collection system will also aid in the
control of fugitive emissions. Also, fixed or movable
hoods or an enclosed building with evacuation to a fabric filter,
will normally control fugitive emissions.
4-139
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4.4.1.4 Control Techniques - At well-collected secondary
lead smelters, baghouses or wet scrubbers are used to
collect dust and fumes from the furnaces. When fabric
filters are used to control blast furnace emissions, they
are normally preceded by an afterburner to incinerate
hydrocarbons that might blind the fabric and to convert the
carbon monoxide to carbon dioxide. Afterburners are not
needed for reverberatory furnaces, since the excess air and
temperature are usually sufficient to incinerate carbon
2
monoxide and hydrocarbons.
A. Wet Collectors; Although wet scrubbers have shown
collection efficiencies as high as 95 to 98 percent when
treating lead fumes having particles no smaller than 0.5 ym,
their collection efficiencies for smaller particles is
4
lower. High levels of energy input are required to achieve
a high-efficiency collection of submicron particles. Pressure
differences on the order of 7.5 to 24.9 kPa (30-100 in. H_0)
are required to provide good cleanup. In addition, water
scrubbing may cause corrosion problems. SO,, in the gas
stream will be absorbed into the scrubbing water to form
dilute sulfurous acid. Therefore it may be necessary to add
lime, caustic soda, or similar chemicals to the water to
minimize corrosion. The dust is recovered as a dilute
slurry. If the lead oxide in the dust is to be recovered,
some form of separator must be provided.
4-140
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If the sulfur content of the charge is relatively high,
the scrubber provides an advantage over a fabric filter
since it may be designed solely for absorption of S02-
Sulfur will arise from the fuel charge to the furnace and
from lead sulfate or sulfuric acid used in lead storage
batteries. In these cases, however, it is likely the
scrubber would be placed after an existing filter.
B. Afterburners: Afterburners are oil- or gas-fired
burners placed directly above the charging door of the blast
furnace. This section should be sufficiently tall to allow
for a residence time of approximately 0.5 second and should
be equipped to raise the gas temperature to at least 650°C
(1200°F) and as high as 1100°C (2000°F) to ensure proper
incineration of the hydrocarbons and carbon monoxide.
C. Fabric filters; Shaker-type baghouse filters are the
most effective means of controlling lead fume emissions from
secondary furnace operations. Collection efficiencies may
exceed 99 percent, depending upon particle size and inlet
loading. In addition, because the fabric filter is a dry
collection device, the lead oxide collected is suitable for
return to the furnace for further processing.
The hot gases from the furnace must first be cooled,
however, to a temperature that can be tolerated by the
P
filter material. Dacron bags, for instance, may be oper-
4-141
-------
ated only at temperatures up to 150°C (300°F). Cooling may
be done by dilution with ambient air, heat exchange, or a
combination of these. Installations with filtering velocities
of 4 cm/s (2 fpm) have proved satisfactory in long-term
performance.
Performance of fabric filters on a natural-gas-fired
reverberatory furnace is indicated by Table 4-27. The
charge to the furnace includes lead oxide dust in addition
to lead battery plates. The hearth is about 7.6 meters (25
feet) long and 2.4 meters (8 feet) wide with the roof about
0.9 meters (3 feet) above the melt. The natural gas burners
operate at full capacity except for brief morning periods
during which the ductwork is cleaned. The gas firing rate
is 13.6 m /min (480 cfm). The furnace is operated under a
slight draft to prevent fugitive dust emissions. The charge
increments are approximately 270 to 320 kg (600 to 700 Ibs).
The feed is loaded into a hopper over the feed ram with a
front loader; the ram operates continuously. The feed rate
is controlled by the buildup of unmelted feed in the front
of the furnace.
The exhaust gases from the reverberatory furnace pass
through a brick flue, a cooling tower, three water-cooled
cyclones, and then to a baghouse. The baghouse has four
sections of 120 bags per section. Design air flow rate is
850 m /min (30,000 cfm). Bag shaking time is 8 minutes per
4-142
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Table 4-27'. PERFORMANCE OF A FABRIC FILTER ON A SECONDARY LEAD
REVERBERATORY FURNACE
U)
Run
Lead production,
'1g/hr (tons/hr)
Stack effluent:
Flow rate, dscm/min (dscfm)
Temperature, °C (°F)
Particulate emissions:
Probe and filter catch
mg/dscm (gr/dscf)
mg/m (gr/acf)
kg/hr (Ib/hr)
kg/Mg of product
(Ib/ton of product)
1
1.9 (2.1)
664.5 (23,480)
51.1 (124)
5.49 (0.002)
4.81 (0.0021)
0.222 (0.489)
0.102 (0.204)
2
6.4 (7.1)
639.6 (22,600)
55.6 (132)
7.55 (0.003)
6.18 (0.0027)
0.288 (0.635)
0.132 (0.265)
3
1.9 (2.1)
564.3 (19,940)
47.2 (117)
9.61 (0.004)
8.24 (0.0036)
0.32 (0.721)
0.150 (0.300)
Average
3.4 (3.8)
622.8 (22,010)
51.3 (124)
7.44 (0.003)
-
0.279 (0.615)
0.128 (0.256)
-------
half hour, with no shaking during the last 22 minutes of a
half-hour cycle. Each section is cleaned for 2 minutes.
The design collection efficiency is 99.9 percent.
4-144
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4.4.1.5 Control Costs - Model plant cost analyses for
emission control equipment are performed for the two major
furnaces used in the secondary lead industry: reverberatory
and blast furnaces.
A. Reverberatory Furnace - A reverberatory furnace
with a capacity of 45 Mg/day (50 TPD) is a typical model
size for the emission control cost analysis. Exhaust flow
from this type and size of furnace is 15.8 m /s at 730°C
(33,500 acfm at 1350°F). Emissions are about 216 kg/h (475
Ib/hr) particulate, 23 percent of which is lead. These vent
gases are cooled by radiant U-tube coolers to 260°C (500°F),
then further cooled by dilution air to 218°C (425°F) before
they enter a fabric filter. The fabric filter is designed
to clean 9.3 m /s (19,700 acfm) at a filter velocity of 1
cm/s (2 fpm). It is equipped with bags to withstand 218°C
(425°F) temperature and mechanical-shaker cleaning. The 75-
hp fan system will handle 9.3 m /s (19,700 acfm) at a system
pressure drop of 3.5 kPa (14 in. W.G.). This level of
control (>99 percent) will enable the source to meet the
average state particulate limitation of 2.4 kg/h (5.2 lb/
hr) .
The capital costs for the above system are estimated at
$470,000, including fabric filter, U-tube cooler, fan sys-
tem, and ductwork.
See Section 2.9 and Appendix B for discussion of cost analyses,
Detailed cost studies are available from EPA upon request.
4-145
-------
The annualized costs are estimated at $194,000, includ-
ing utilities, labor, maintenance, overhead, and fixed costs
(with capital recovery).3 If a dust recovery credit of
$0.11/kg ($0.05/lb) is included, the annual credit amounts
to $141,000; thus, the annual cost is $53,000. The annual
operating time is assumed at 6,000 hours and annual labor is
estimated at 3000 hours.
The capital and annualized costs are expressed below in
terms of exhaust flow rate and annual labor hours:
S.I, units
Capital, $ = 8.97 x 104V°'6
Annualized,b $ = 807V + 19.6H + 2.34 x 104V°'6
V = m3/s @ 730°C
H = annual labor hours
5 < V < 50
range
English units
Capital, $ = 906Q0'6
Annualized,b $ = 0.364Q + 19.6H + 236Q0'6
Q = acfm @ 1350°F
H = annual labor hours
10,000 < Q < 100,000
range
a
See Section 2.9 and Appendix B for discussion of cost analyses
Detailed cost studies are available from EPA upon request.
Does not include any credit for recovered dust.
1-146
-------
B. Blast Furnace - A 45 Mg/day (50 TPD) capacity
blast furnace is selected as the model plant size to determine
the control costs. The furnace exhausts 15.1 m /s at 260°C
(32,000 acfm at 500°F) including charge-door draft air.
Particulate emissions are estimated at 230 kg/h (504 Ib/hr)
with a 23 percent by weight lead content. The exhaust gases
enter a direct flame afterburner equipped with a heat re-
covery unit. The afterburner is designed for a residence
time of 0.5 seconds and an operating temperature of 980°C
(1800°F) to allow complete combustion of carbon monoxide and
hydrocarbons. The heat exchanger recovers 50 percent of the
total stream heat content,thereby reducing the temperature
of the gas to 650°C (1200°F). These gases enter a carbon
steel U-tube cooling system designed to reduce the tempera-
ture of 25.8 m3/s (54,600 acfm) from 650°C to 260°C (1200°F
to 500°F). The gases are cooled further to 150°C (300°F) by
diluting with ambient air prior to entering an automatic
shaker fabric filter. The fabric filter is designed to
handle 24.6 m /s (52,000 acfm) at a filtering velocity of 1
P
cm/s (2 fpm). It is equipped with Dacron bags. A 200-hp
fan system provides adequate service for a total system
pressure drop of about 3.8 kPa (15 in. W.G.). This control
technique will bring the source into compliance with an
average state regulation of 3.9 kg/h (8.6 Ib/hr) of parti-
culate emissions with an overall efficiency of more than 99
percent.
4-147
-------
The capital costs for the above system are estimated at
$1.24 million, including afterburner, heat recovery unit, U-
tube cooler, fabric filter, fan system, and ductwork.
The annualized costs are estimated at $615,000, in-
cluding utilities (with natural gas requirements for after-
burners) , maintenance, labor, overhead, and fixed costs
(with capital recovery). This estimate is based on 6000
hours of total operating time, 3000 hrs/yr annual labor, and
does not include value of recycled dust. Assuming a value
of HC/kg (5£/lb) for tne recycled dust, an annual credit of
$150,000 should be considered in the overall cost of opera-
tion.
The capital and annualized costs (including recycle
credit) are expressed below in terms of exhaust volume,
annual labor hours, and production rate:
S.I, units
Capital, $ = 2.43 x 105V°'6
Annualized, $ = 15,400V + 63,500V°'6 + 19.6H - 13.1M
V = m3/s at 260°C
H = annual labor hours
M = annual production, Mg
5 < V < 50
range
English units
Capital, $ = 2460Q0'6
Annualized, $ = 7.25Q + 642Q0'6 + 19.6H - 11.9P
a
See Section 2.9 and Appendix B for discussion of cost analyses.
Detailed cost studies are available from EPA upon request!
4-148
-------
Q = acfm at 500°F
H = annual labor hours
P = annual production rate, tons
104 < Q < 105
range
4.4.1.6 Impacts
A. Emission Reduction
Particulate emission reductions by air pollution control
systems on blast furnaces are about 120 kg/Mg (240 Ib/ton)
of product and 110 kg/Mg (220 Ib/ton) of product for the
reverberatory furnace. Lead content of these emissions are
23 percent by weight.
B. Energy Impact
Energy requirements for the production of secondary
lead is not available . However, primary lead blast and
reverberatory furnaces consume 7.5 GJ/Mg of lead (7.5 MM
Btu/ton) and 5.0 GJ/Mg of lead (5.0 MM Btu/ton), respectively.16
Energy consumption for secondary lead processes may be
similar. Fabric filter systems installed on the model blast
and reverberatory furnaces require 0.30 GJ/Mq (0.30 MM Btu/
ton) and 0.10 GJ/Mg of lead (0.10 MM Btu/ton), respectively.
C. Wastewater Impact
Process wastewater data are not available; however, no
additional wastewater impact is encountered when fabric filters
are utilized. When high-energy wet collectors are used, settling
4-149
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tanks and ponds have been used to precipitate the collected
solids. The precipitate is removed, dried, and fed back to
the furnace. Scrubbing water will pick up sulfur dioxide
from the gas stream causing the water to become acid.
Alkali can be added to the scrubber to control pH. Salts
that precipitate with the collected dust are also returned
2
to the furnace and usually become part of the slag.
D. Solid Waste Impact
No process solid waste data are available; however,
dust collected by control equipment is recycled. The
total solid waste generation by air pollution control
equipment amounts to about 110 kg/Mg product (220 Ib/ton)
for the reverberatory and blast furnaces.
4-150
-------
4.4.2 Brass and Bronze Industry
Brass and bronze are generally considered to be copper-
based alloys with zinc, tin, and other metals such as lead,
aluminum, manganese, and silicon as secondary components.
A variety of brass and bronze alloys are produced each year.
In 1975, production of brass and bronze ingots was estimated
at 210 Gg (232,000 tons), consuming 12.2 Gg of refined lead
(13,400 tons). Twenty-eight percent of the total production
in 1974 consisted of tin bronze, aluminum bronze, and nickel
bronze. The remaining 72 percent of total production con-
sisted of leaded red and semi-red brass, high-leaded tin
bronze, yellow brass, and manganese bronze.
The alloys are produced in reverberatory, rotary,
crucible, or electric induction furnaces. The tin bronze,
aluminum bronze, and nickel bronze do not contain lead,
and production of these alloys does not generate significant
lead emissions. The other alloys, leaded red brass, semi-
red brass, high-leaded tin bronze, and leaded nickel
bronze, contain significant amounts of lead. Production
of these alloys generated 47 Mg of lead emissions (52 tons)
in 1975.
4.4.2.1 Process Description - Figure 4-28 illustrates the
processes involved in production of brass and bronze ingots,
including preparation of raw materials.
4-151
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DOMESTIC
&
INDUSTRIAL
SCRAP
SEPARATION
PROCFSS
REVERBERATORY
FURNACE
COOLING FABRIC
SURFACE COLLECTOR
GAS OR Oil
FUEL » AIR
MECHANICAL
HYDROMETALLURGICA1
PYROMETAUJRGICAl
SLAG
METAL
PRODUCT
t
n
FAN
Figure 4-28., Process flow sketch of brass/bronze
reverberatory furnace.
-------
The basic raw material consists primarily of copper
based alloy scrap. The scrap is treated by mechanical,
hydrometallurgical, or pyrometallurgical methods to remove
contaminants. Most raw material scrap is treated by mechan-
ical methods such as hand sorting, stripping, shredding,
magnetizing, and briquetting. These methods cause little or
no atmospheric emissions. The hydrometallurgical methods
include a liquid medium and cause no air pollution. Some
amount of raw material is cleaned by the pyrometallurgical
methods, which include sweating, burning, drying, and blast
furnace or cupola processing. Usually a charge containing
slags and skimmings is treated in blast furnaces. These
processes, which use external fuel, are major sources of air
pollution.
Brass and bronze ingots are produced from a number of
furnaces through a combination of melting, smelting, refining,
and alloying of the processed scrap material. Direct-fired
furnaces, such as the reverberatory and rotary types, and
indirect-fired furnaces, such as the crucible and electric
induction types, are used for ingot production. Figures 4-29
and 4-30 show typical furnaces used in brass and bronze
production. The scrap materials, along with solid or liquid
fluxes, are charged to the furnace. The fluxes can be
nonmetallic materials, pure metals, or alloys. Heat is
4-153
-------
Figure 4-29. Brass reverberatory furnace,
(Courtesy of H. Kramer Co., Chicago)
4-154
-------
Figure 4-30. Gas-fired rotary brass melting furnace
(Courtesy of H. Kramer Co., Chicago)
4-155
-------
supplied by burners fueled with gas or oil. Molten metal is
formed and refined by blowing compressed air into the metal
bath to oxidize the metallic and nonmetallic contaminants.
Oxides of metals such as iron, manganese, silicon, and
aluminum are lighter than the molten bath and are removed as
slag. Fluxes such as charcoal, borax, sand, limestone, and
caustic soda provide entrainment for the metallic oxide
impurities. Virgin metal or specialized scrap is added as
required for modification of the alloy. The molten metal is
poured into molds and cast at temperatures ranging from 650
17
to 1320°C (1200 to 2400°F). After casting, the shapes may
be rolled into plates, sheets, or strips; extruded into
rods, bars, or seamless tubes; or drawn into wire.
4.4.2.2 Emissions
A. Scrap Treatment; Effluents from preparation of raw
materials by pyrometallurgical scrap treatment methods
contain combustion products and impurities including metal-
lic fumes, halogens, and hydrocarbons from the charge.17
The blast furnace emits 9 g particulate/kg of material
charged (18 Ib/ton) and the cupola emits about 36.5 g
18
particulate/kg of charge (73 Ib/ton). The major component
of the emission is zinc oxide. Data are not available on
lead contents of effluents from the furnace process. Source
tests in Los Angeles indicate that the uncontrolled emissions
4-156
-------
from burning scrap contain particulate matter in concentra-
3 19
tions as high as 67 g/m (29 gr/scf) at 12 percent CO,.,.
Since a small fraction of the total industry scrap is pro-
cessed and high control efficiency is applied in pyrometal-
lurgical methods, the overall lead emissions from raw
material preparation are very small.
B. Ingot Furnace; Emission rates from brass and bronze
furnaces depend on the type of fuel and on furnace tempera-
tures. Pollutants are emitted during charging, slag tapping,
alloying, and pouring operations. The emissions contain
metal oxide fumes, combustion products, carbon particles,
mechanically produced dust, and unburned fuel oil mist. The
metal oxides are present in submicron size as condensed
fume.
In direct-fired furnaces, the very hot and high-velo-
city combustion gases come in direct contact with the
metals in the charge, thus significant amounts of metal
oxides are released into gaseous effluents. Reverberatory
furnaces emit greater quantities of air pollutants than the
other furnaces. Electric induction furnaces create
insignificant amounts of pollution. Typical quantities of
particulates emitted from reverberatory, rotary, crucible,
and electric induction furnaces are given in Table 4-28.
4-157
-------
Table 4-28. PARTICULATE EMISSIONS FROM BRASS AND
18
BRONZE INGOT PRODUCTION
Type of furnace
Reverberatory
Rotary
Crucible
Electric
induction
Particulate emission factor,,
g/kg charge
35
30
6
1
Ib/ton charge
70
60
12
2
The exhaust gas parameters for a reverberatory furnace
are given in Table 4-29.
Information on the types of products produced from
different furnaces is not available; however, about 90
percent of brass and bronze production is done in reverbera-
tory furnaces. On the average about 80 percent by weight
of the charge is converted to product.
Zinc oxide constitutes 60 to 95 percent of the par-
ticulate material collected in a control system, and lead
oxide content normally ranges from 6 to 8 percent.17 Flue
dust samples collected by Bureau of Mines contained 2.5 to
8.5 percent lead.22'23 Tests conducted in Los Angeles
County indicated a 15 percent lead oxide content of fume
from representative red and yellow brass furnaces and a 56
percent lead oxide content of particulate from producing
high-leaded alloys.19
4-158
-------
Table 4-29. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM A BRASS AND BRONZE REVERBERATORY FURNACE
Parameters
Gas flow rate
Temperature
Grain loading
Particle size
distribution
Lead content
Of
particulate
Emission
factors
0 particulate
0 lead
Standard
international
units
4.5 m / s • Mg • h
product
925-1315°C
0.12-9.4 g/m3
0.03-0.5 ym
(majority)
high-leaded 58% w
yellow and red 15%
other brass and
bronze 7% w
35 g/kg
charge
English
units
8600 acfm/tph
product
1700-2400°F
0.05-4.1 gr/scf
0.03-0.5 ym
(majority)
w
70 Ib/ton
charge
Determine from percentage above
I
References
3
21
17
19
19
19
17,22,23
18
Flow rates can vary according to the hooding arrangement
required. Volume given is at 120°C (250°F).
Temperature is usually reduced to 120°C (250°F).
Dependent upon lead content of the product.
4-159
-------
For 1974, an estimated 54 Mg of lead (58 tons) was emitted
by this industry, as shown in Table 4-30. With a 10 percent
production decrease, the 1975 lead emissions to the atmos-
phere were 47 Mg (52 tons).
The lead emission factor for high-leaded alloys produced
by a reverberatory furnace is estimated at 25 g/kg product
(50 Ib/ton); for red and yellow brasses the factor is 6.6 g/kg
product (13.2 Ib/ton). Based on an average 7 percent par-
ticulate lead content, the lead emission factor for the pro-
duction of other alloys in reverberatory furnaces is estimated
at 2.5 g/kg (5.0 Ib/ton).
13
4.4.2.3 Fugitve Emissions
Figure 4-31 shows a process flow diagram for brass and
bronze production with the potential fugitive particulate
emissions as dotted lines. Some of the major sources of
fugitive emissions include insulation burning, reverberatory
furnace, and rotary furnaces. It is estimated that fugitive
emissions are equal to 5 percent of an operation's stack
emissions. For a plant producing 30,000 Mg (33,000 tons)
of lead Der year, the uncontrolled process fugitive par-
ticulate emissions are 354 Mg (389 tons) per year. Lead
particulates are between 1.0 and 12.0 percent by weight of
the total particulate emissions.
Better control of operation parameters and procedures
such as tapping at the lowest possible melt temperature will
4-160
-------
SWEATING
FURNACE
DRYING
(REMOVING OIL
'AND ORGAN ICS)
®
LOW MELTING
I) TEMPERATURE
ELEMENTS
TIN AND
LEAD
•• COPPER
BURKING
3F INSULATION
FROM WIRE
AND
COPPER
ALLOYS
MELTING AND
SMELTING FURNACES
V.
©
V
ELECTRIC
INDUCTION
FURNACE
REVERBERATORY
FURNACE
ROTARY
FURNACE
CRUCIBLE
FURNACE
MOLDS
COKE
CUPOLA
FURNACE
•^J
4
COPPER,
BRO;;XF. ,
AND EilASS
INGOTS
AND
CASTINGS
Figure 4-31. Process flow diagram for secondary brass/bronze (copper alloy)
production showing potential industrial process fugitive particulate emission points
-------
often control fugitive emissions from various furnace
tapping operations. Fixed or movable hoods over the tapping
operations will provide for better control of fugitive
emissions. In addition, curtains which help direct fugitive
emissions into the hood will increase capture efficiencies.
4.4.2.4 Control Techniques - The mechanical and hydro-
metallurgical processes cause little or no air pollutant
problems and require no control. Pyrometallurgical processes
release some air pollutants and need control. Baghouses
are effective are the generally accepted air pollution
control device in the brass and bronze industry. Wet
scrubbers and electrostatic precipitators have also been
2 3
particularly successful in collection of zinc oxide fumes.
A. Fabric Filters: Generally, the fumes are captured by
the auxiliary hoods and vented through a cooling device to a
baghouse. Temperature limitations of the filter fabrics
require cooling and dilution of the incoming particulate-
laden air stream. The initial cooling is often accomplished
by means of water sprays. One cooling system consists of a
water-jacketed cooler followed by air-cooled radiation
19
convection columns.
Tests conducted on baghouses showed efficiencies
ranging between 95 and 99.6 percent. Fabric filters are
usually tubular. A critical design factor for a tubular
baghouse is the filtering velocity. A filter velocity of
4-162
-------
Table 4-30. LEAD EMISSIONS FROM BRASS AND BRONZE PRODUCTION IN 1974
Type of product
Red, yellow, manganese
High-leaded
Other brass and bronze
1974 Production,1
Gg
141
30
66
10J ton
155
33.2
73.1
19
Lead content,
% wt
15
56
7
Total lead emissions
_ , a
Lead emissions,
Mg
26.1
20.9
5.8
52.8
tons
28.8
23.0
6.4
58.2
Based on 80 percent yield from charge, average particulate emissions of 33 g/kg
charge (66 Ib/ton), and an assumed overall control efficiency of 97 percent.
OJ
-------
1.3 cm/s (2.5 fpm) is recommended for collecting relatively
small concentrations of fumes from brass furnaces. Larger
concentrations of fumes require a lower filtering velocity.19
Normal pressure drop ranges from 0.5 to 1.5 kPa (2 to 6
in. H^O). Maintenance problems with baghouses in the brass
•n
and bronze industry are insignificant. Dacron is the most
widely used fabric though many other materials are employed.
Table 4-31 indicates performance of fabric filters on
reverberatory furnaces. The furnace capacity is approxi-
mately 91 metric tons (100 tons) for brass. Air lancing is
used to remove the iron from the melt. Exhaust gases pass
from the furnace directly through a 27-37 meters (30-40 yards)
refractory flue which serves as an afterburner. From that
section of the flue, the gases pass through approximately
9.1 meters (30 feet) of water jacketed ductwork, and through
a series of U-tube exchange elements upstream from a
baghouse. The U-tubes are approximately 9.1 meters (30 feet)
high and are used to achieve the desired baghouse inlet
temperature [71°C to 107°C (160°F to 225°F)]. The tubes per-
mit temperature control without the use of water sprays.
The baghouse has 36 compartments with 25 bags per
compartment. Two suction fans draw approximately 1250
3
m /min (44.000 cfm) of gas through the baghouse. The
baghouse uses electrically timed mechanical shakers for
4-164
-------
Table 4-31. PARTICULATE EMISSIONS FROM A BRASS AND BRONZE REVERBERATORY FURNACE
Run
Test time, min.
Heat time, min.
Ingots produced/heat,
metric tons (tons)
Stack effluent:
Flow rate, dscm/min
(dscfm)
Temperature, °C (°F)
Particulate emissions:
Probe and filter catch
mg/dscm (gr/dscf)
mg/m (gr/acf)
kg/hr (ib/hr)
kg/metric ton of
product (Ib/ton of
product)
1
120
1140
44.6 (49.1)
779 (27,500)
47.8 (118)
13.7 (0.006)
11.4 (0.005)
0.703 (1.55)
0.299 (0.60)
2
700
1183
54.4 (59.9)
853 (30,100)
41.7 (107)
11.4 (0.005)
11.4 (0.005)
0.567 (1.25)
0.205 (0.41)
3
747
1326
49.0 (56.4)
719 (25,400)
41.1 (106)
16.0 (0.007)
13.7 (0.006)
0.626 (1.46)
0.215 (0.43)
4
780
1372
49-0 (53.9)
767 (27,100)
45 (113)
9.15 (0.004)
9.15 (0.004)
0.44 (0.99)
0.210 (0.42)
Average
656
1255
49.8 (54.8)
779 (27,500)
43.9 (111)
13.7 (0.006)
11.4 (0.005)
0.595 (1.31)
0.232 (0.46)
-------
cleaning. The 36 compartments are divided into 3 separate
systems for cleaning. The total cleaning time per system
is 30 minutes. Each compartment shakes for 60 seconds,
and the lapsed time between shaking of successive compart-
ments within a system is 90 seconds.
B. Wet Collectors: High energy venturi scrubbers can be
used for high-efficiency cleaning. Pressure drops across
the scrubber of 12.5 to 14.9 kPa (50 to 60 in. H20) and
water rates to the scrubber throat ranging from 1.4 to 2
o o o r\
l/m (10 to 15 gpm/10 acfm) are required/
C. Electrostatic Precipitators: Electrostatic precipitators
are often highly efficiency, but are not ideally suited for
the brass and bronze industry, mainly because of the low
20
exhaust gas flow rates. Lead oxide is particularly
difficult to collect because of its relatively high
19
resistivity. Information from a few installations that
use wet scrubbers and electrostatic precipitators indicates
significant maintenance problems and low efficiencies.
4.4.2.5 Control Costs - A reverberatory furnace rated at
a production capacity of 45.3 Mg/day (50 TPD) is considered
the typical model size to determine control costs. The
o
furnace exhausts 18.4 m /s at 1090°C (39,000 acfm at 2000°F)
and emits 83 kg/h (183 Ib/hr) particulate matter, of which
15 percent is lead. The gases enter a quench tower, where
they are cooled to 120°C (250°v) before they enter an
4-166
-------
insulated fabric filter. The shaker-type fabric filter is
3
designed to handle 8.5 m /s (18,000 acfm) at a superficial
filter velocity of 1.2 cm/s (2.5 fpm). A fan system rated
3
at 8.5 m /s (18,000 acfm) and a system pressure drop of 1.8
kPa (7 in. W. G.) is also required. This control technique
will permit compliance with the average state particulate
limitation of 3.6 kg/h (7.9 Ib/hr), with an overall efficiency
of over 99 percent.
Capital costs are estimated at $407,000, including quench
tower, pump, hold tank, collector, insulation, fan system,
«
and ductwork.
Annualized costs are estimated at $202,000, including
utilities, labor, maintenance, overhead, fixed costs (with
capital recovery), and solid waste disposal in sealed
barrels. An annual operating time of 6000 hours and annual
labor of 2000 hours are assumed.
Capital and annualized costs are expressed below in
terms of exhaust flow rate, annual labor hours, and furnace
capacity:
S.I. units
Capital, $ = 7.1 x 104V°'6
Annualized, $ = 587V + 1030 M + 19.6H + 2.1 x 105V°'6
V = m3/s at 1090°C
H = annual labor hours
M = furnace capacity, Mg/day product
Range: 6 < V < 60
range
a
See Section 2.9 and Appendix B for discussion of cost analyses
Detail cost studies are available from EPA upon request.
4-167
-------
English units
Capital, $ = 716 Q°'6
Annualized, $ = 0.277Q + 932T + 19.6H + 187Q0'6
Q = acfm at 2000°F
H = annual labor hours
T = furnace capacity, TPD product
(for solid waste disposal costs)
Range: 13,000 < Q <130,000
range
4.4.2.6 Impact
A. Emission Reduction
Particulate emission reductions for control systems on
reverberatory furnaces are estimated at 35 kg/Mg product
(70 Ib/ton) with a lead content ranging between 7 and 58
percent by weight, depending on the product specification.
B. Energy Impact
The total energy required to produce brass at one plant
is about 3.0 GJ/Mg product (3.0 MM Btu/ton) for a 46 Mg
(50 ton) capacity furnace producing 2.3 Mg/h (2.5 tph) of
19
brass. The fabric filter system on the model furnace
requires about 0.05 GJ/Mg product (0.05 MM Btu/ton) to
operate fans and auxilary equipment. Therefore, the
energy impact is about 1.7 percent. If high energy wet
scrubbers, operating at 12 kPa (50 in. WG) pressure drop,
were used the energy impact would be about 12 percent.
4-168
-------
C. Wastewater Impact
Fabric filters do not generate additional wastewater
and wet collectors are used rarely if at all. No process
wastewater data are available however no impact is expected
by the application of control systems.
D. Solid waste Impact
Solid wastes generated by brass and bronze furnaces are
generally disposed of by bagging or barreling and ultimately
placed in landfills or open piles. Annual solid waste tonnages
2
for the entire industry are only about 9100 Mg (10,000 tons),
corresponding to an average of 43 kg/Mg product (86 Ib/ton).
The reverberatory furnace will generate about 35 kg/Mg product
(70 Ib/ton) of solid wastes from air pollution control,
corresponding to 80 percent of the total solid wastes
generated. Solid wastes by the control of emission from
other furnaces can be estimated by the emission factor in
Table 4-28.
4-169
-------
4.4.3 References for Section 4.4
1. U.S. Department of Interior, Bureau of Mines. Washington,
D.C., 1975.
2. Background Information for Proposed New Source Perfor-
mance Standards. U.S. Environmental Protection Agency.
Research Triangle Park, North Carolina. APTD-1352.
June 1973. p. 128.
3. Hardinson, L.C. Study of Technical and Cost Informa-
tion for Gas Cleaning Equipment in the Lime and Sec-
ondary Non-Ferrous Metallurgical Industries. National
Technical Information Service. Stamford, Connecticut.
PB-198-137. December 1970.
4. Nance, J.T. and K.D. Luedtke, Lead Refining In: Air
Pollution Engineering Manual, U.S. DHEW, NCAPC. PHS
Publication No. 999-AP-40. Cincinnati, Ohio 1967. p.
302.
5. Crane, G.B. Control Techniques of Lead Emissions.
Draft. U.S. Environmental Protection Agency- Research
Triangle Park. North Carolina. February 1971. p. 4-
32.
6. Exhaust Gases From Combustion and Industrial Processes.
Engineering Science, Inc. Washington D.C. Contract
No. PB-204-861. U.S. Environmental Protection Agency.
October 1971. p. VI-60.
7. EPA Test No. 71-C1-27 at American Smelting and Refining
Co. Engineering Science, Inc. for U.S. Environmental
Protection Agency. Research Triangle Park, North
Carolina. February 1972.
8. EPA Test No. 71-C1-30 at West Coast Smelting and Re-
fining Company. Engineering Science, Inc. for U.S.
Environmental Protection Agency. Research Triangle
Park, North Carolina. March 1972.
9. EPA Test No. 71-C1-76 at R.L. Lavin and Sons, Inc.
Engineering Science, Inc. for U.S. Environmental Pro-
tection Agency- Research Triangle Park, North Caro-
lina. March 1972.
10. EPA Test No. 74-SLD-l. Preliminary Report. Emission
Testing Branch. Environmental Protection Agency -
Research Triangle Park, North Carolina. Contract No.
68-02-0225, Task No. 22, July 1974.
4-170
-------
11. Tests No. 72-C1-7,8,29, and 33. Emission Testing Branch.
Environmental Protection Agency, Research Triangle Park,
North Carolina. Contract No. 68-02-0230. August 1972.
12. Mcllvaine Scrubber Manual. Mcllvaine Co. North Brook,
Illinois, 1974. Sec. 3340. p. 118.
13. Control Program Guideline for Industrial Process
Fugitive Particulate Emissions. Preliminary Draft.
PEDCo-Environmental Specialists, Inc. Cincinnati, Ohio.
EPA Contract No. 68-02-1375. Task No. 33. December 10,
1976.
14. Compilation of Air Pollutant Emission Factors. Second
Edition. U. S. Environmental Protection Agency, Office
of Air and Water Management, Office of Air Quality Planning
and Standards. Publication No. AP-42. Research Triangle
Park, North Carolina. February 1976.
15. Multimedia Environmental Assessment of the Secondary
Nonferrous Metal Industry, Volume II: Industry Profile.
Radian Corporation. Contract No. 68-02-1319, Task No. 49.
Austin, Texas. June 21, 1976.
16. Fejer, M.E. and D.H. Larson. Study of Industrial Uses
of Energy Relative to Environmental Effects. Institute
of Gas Technology. Chicago, Illinois. EPA Contract
No. 68-02-0643. July 1974.
17. Air Pollution Aspects of Brass and Bronze Smelting and
Refining Industry. U. S. Department of Health, Education,
and Welfare. National Air Pollution Control Admini-
stration, Raleigh, N. C. Publication No. AP-58.
November 1969.
18. Brass and Bronze Ingots (Copper Alloys). In: Compilation
of Air Pollutant Emission Factors. U. S. Environmental
Protection AGency. Publication No. AP-42. Washington,
D. C. April 1973.
19. Danielson, T. A. (ed.) Secondary Brass and Bronze
Melting Processes. In: Air Pollution Engineering
Manual. Environmental Protection Agency. Research
Triangle Park, N. C. May 1973.
20. Hardinson, L. C. and Herrington, H. R. Industrial Gas
Cleaning Institute, Inc. Study of Technical and Cost
Information for Gas Cleaning Equipment in the Lime and
Secondary Nonferrous Metallurgical Industries. The
National Air Pollution Control Administration. Contract
No. CPA 70-150. Durham, N. C. December 1970.
4-171
-------
21. Powell, H. E., et al. Recovery of Zinc, Copper, and
Lead. Tin Mixtures from Brass Smelter Flue Dusts.
United States Department of the Interior. Bureau of
Mines. Report of Investigation 7637. Washington, D.C.
1972.
22. Fukubayashi, H. H. et al. Recovery of Zinc and Lead
from Brass Smelter Duct. United States Department of
the Interior. Bureau of Mines. Report of Investigation
7880. Washington, D. C. 1974.
23. Air Pollution Control in the Secondary Metal Industry.
(Presented at NASMI's First Air Pollution Control
Workshop, Pittsburgh, Pa. June 1967). Published as a
Membership Service by National Assocation of Secondary
Materials Industries, Inc. New York, N. Y. 1967.
4-172
-------
4.5 FERROUS METALS AND ALLOY PRODUCTION
An estimated 1.77 Gg of lead (1950 tons) was emitted to
the atmosphere in 1975 by the production of ferrous metals and
alloys. Emissions for each source were as follows: gray iron
foundries, 1.08 Gg (1192 tons); iron and steel plants, 605 Mg
(667 tons); and ferroalloy production facilities, 82 Mg (91
tons), not including fugitive emissions.
4.5.1 Gray Iron Foundry
Gray iron is produced in cupola, electric and rever-
beratory furnaces. The estimated throughputs of raw materials
in 1975 are 12.4 Tg (1.37 x 107 tons) for the cupola, 4.26 Tg
(4.7 x 106tons) for electric furnaces, and 1.09 Tg (1.2 x 106
tons) for the reverberatory furnace. Approximately 85 percent
2
of the charge is metal, and therefore a total of 15.1 Tg of
gray iron (1.67 x 10 tons) was produced. Lead emissions from
the gray iron industry in 1975 are estimated at 1.08 Gg
(1192 tons).
4.5.1.1 Processes - Figure 4-32 is a flow diagram of a
typical foundry operation. Descriptions of the iron melting
furnaces from references 4 and 5 are summarized in the
following paragraphs.
A. Cupola: A cupola is a vertical furnace consisting
of a cylindrical steel shell protected with a refractory
lining or with a water-cooled steel shell. Cupolas range
from approximately 0.69 to 3.81 m in diameter (27 to
150 in) and are supported on structural steel legs. Air is
4-173
-------
Binder
Dust and gases
Return
sand
a.^7^
. t
-' ' - Particulate
emissions
<^ CASTING
SHAKEOUT
Dust
FINISHING
AND
SHIPPING
COOLING AND
CLEANING
Core sand
and binder
SAND
PREPARATION
CORE
MAKING
Figure 4-32. Production flow diagram for a typical gray iron foundry.
(Courtesy of TRC of New England, Wethersfield, CT)
-------
supplied through a windbox and tuyeres by positive dis-
placement, centrifugal, or fan-type blowers. As in blast
furnaces, air is the largest single constituent of the heat,
its weight being dependent on the size of the furnace and
the metal to be melted. Some foundries recycle waste heat
from the cupola to preheat the combustion air as an economy
4
measure. This practice is known as a hot blast operation.
A diagram of a cupola is shown in Figure 4-33.
SPARK
ARRESTER
LINING
SHELL
TAPPING SPOUT
BOTTOM PLATE
SAND BOTTOM
•''.-".' / FOUNOA'T'I ON • '•.'-'->
Figure 4-33. Cupola furnace cross-section for
J 4-' 5
gray iron production.
(Courtesy of American Foundrymen's Association)
4-175
-------
A cupola is prepared for melting by securing the bottom
drop doors, placing a layer of sand over the door to prevent
heat damage, closing the tap and slag holes, and charging coke
for the bed. The bed is ignited and allowed to burn through.
The charges of coke, flux (limestone, fluorspar and soda ash),
and metal (pig iron, scrap and steel) are placed in alternate
layers up to the charge door which is 4.9 to 6.7 m above the
bottom (16 to 22 feet). The blast is then turned on, and
melting begins. As the coke bed is consumed and the metal
charge is melted, the furnace contents move downward in the
cupola and are replaced by additional charge entering the
cupola through the charging door. When the metal demand is
nearly satisfied, charging ceases and melting continues until
all of the metal has been converted to the molten state. The
molten metal is tapped out and the furnace bottom is dropped,
allowing the excess charge, scrap, and partial burned coke to
fall out. Occasionally, pieces of the metallic scrap in the
bottoms are recycled while the rest of the drop is discarded
with the slag.
Operating factors are broken down into two distinct
groups: 1) methods of operations, such as blast rate and
temperature, type of lining, operating variables of the after-
burner, and 2) the quality of charge materials, including
metal to coke ratios, use of oxygen or natural gas, and the
use of briquettes.
4-176
-------
B. Reverberatory Furnace: A reverberatory furnace operates
by radiating heat from the burner flame, roof, and walls onto
the material heated. Small reverberatory furnaces are used
in preparing gray and white cast iron alloys. The flame and
products of combustion come in direct contact with the solid
and molten metal. The reverberatory furnace usually consists of
a shallow, generally rectangular, refractory hearth for holding
the metal charge. The furnace is enclosed by vertical side
walls and covered with a low, arched, refractory-lined roof.
Reverberatory furnaces are rarely used for melting iron
because of low thermal efficiency, low productivity, high
refractory costs, and difficult metallurgical control. The
curtailment of natural gas and oil supplies has caused further
phasing out of these furnaces.
C. Electric Induction Furnace: Channel and coreless types of
electric-induction furnaces are used for melting cast iron.
In this type of furnace, alternating current is passed through
a primary coil with a solid iron core or hollow barcoil. The
molten iron contained within a loop that surrounds the
primary coil acts as the secondary coil. The alternating
current (from 60 to 1000 hz) that flows through the primary
coil induces a current in the loop. The electrical resistance
of the molten metal creates the heat for me-lting. The heated
metal in the channel type circulates to the main furnace chamber
and is replaced by cooler metal. This circulation results in
uniform metal temperature and alloy composition.
4-177
-------
Use of induction melting has grown during the last decade,
principally because of its potential for air pollution control.
No fossil fuels are used, no significant metal oxidation takes
place during melting, and contamination of the charge is minimal.
Preheaters are being equipped with control devices. Generally,
charge preheaters without air pollution control will not meet
standards, but depends on the fuel and the quality of scrap used.
Induction furnaces utilize air pollution controls during
charging and melting. Pronounced emissions occur if contaminated
scrap is used as charge.
D. Electric-Arc Furnaces: Electric-arc furnaces are commonly
used in the secondary melting of iron where special alloys are
to be made. Though these furnaces may be either direct or
indirect-arc type, the indirect-arc is more commonly used for
nonferrous and high alloy melting than for iron melting, but
it is only found in a few iron foundries. Pig iron and scrap
iron are charged to the furnace and melted, and alloying
elements and fluxes are added at specified intervals. These
furnaces have the advantage of rapid and accurate heat control.
Since no gases are used in the heating process, some un-
desirable effects on the metal are eliminated. Arc furnaces in
the iron industry are most often used to prepare special alloy
irons, and the quality of the material charged is closely con-
trolled. However, foundries also use electric arc melting fur-
naces to produce common, medium tensile strength iron. The charging
of greasy scrap, which would emit combustible air contaminants
4-178
-------
would only needlessly complicate the alloying procedure.
Afterburners are, therefore, rarely required in conjunction with
arc furnace operations. The emissions consist, primarily, of
metallurgical fumes and can be controlled by either a baghouse
or an electrical precipitator.
E. Other Operations: The molten metal is poured into sand
molds designed to produce the desired casting. Molds are
made from sand with wood, metal, or plastic patterns, and
synthetic or sand cores. When the hot metal is poured into
the molds, and when the metal solidifies, the sand and
extraneous material are removed in the shakeout operation.
The castings are abrasively cleaned by shot blast, and
ground. These processes represent minor sources of particulate
emissions, which are frequently controlled. The lead emissions,
however, appear to be negligible relative to the melting
operations.
4.5.1.2 Emissions - Lead is a naturally occuring trace
element in the ferrous materials charged to gray iron
furnaces. Higher lead concentrations, and subsequently
higher lead emissions, are expected from processing of scrap
metals because of contamination with paint, waste oil, and
other lead-bearing compounds.
One of the most important characteristics of cupola
effluent is its high temperature. Particulate matter is
primarily iron oxides, coke particles, and other metal
oxides. In addition to lead-containing particulates, efflu-
4-179
-------
ent from cupolas primarily contain carbon oxides, nitrogen,
oxygen and varying amounts of sulfur dioxide. Smoke, oil
vapor, and fumes make up the remainder of the cupola emissions.
The high-velocity air stream forced through the charge picks up
combustion-related contaminants and dust.
The electric furnaces generate considerably smaller
amounts of air contaminants than do the cupola or rever-
veratory furnace; the amount depends mainly on the condition
of the metal charged. Processing of contaminated scrap or the
addition of magnesium for manufacturing ductile iron would,
however, necessitate air pollution controls. In those cases
design requirements for a baghouse control system with
canopy-type hooding are the same as later described in this
chapter. Table 4-32 presents characteristics of exhaust
gases from the three furnace processes.
Although no extensive study has been performed on lead
emissions from gray iron furnaces, several tests on cupolas
indicate that emissions of lead and particulate vary con-
siderably, depending on the quality of the scrap charged,
cupola blast velocity, temperature of the melt zone, and
lead content. One study reported a range of 0.5 to 2.0
4-180
-------
Table 4-32. CHARACTERISTICS OF TYPICAL EXHAUST GAS
FROM GRAY IRON MELTING FURNACES
Volume, a m /s (acfm)
Temperature, °C (°F)
Grain loading, g/m
(gr/scf)5
Emissions, g/kg
product (Ib/ton)
2
0 particulate
0 lead0
Particle size
Cupola
0.58
982
2.3-4.6
10
0.05-0.6
0. 5-5ym
5-10ym
10-25um
25-50ym
>50ym
(1200)
(1800)
(1-2)
(20)
(0.1-1.1)
4-10%w
2-15%w
4-15%w
5-15%w
45-85%w
Reverberatory
0.85
1565
0.07
1.2
0.006-0.07
H
(1800)
(2850)
(0.03)
(2.4)
(0.012-0.14)
.A.
Electric
0.14
1232
N.,
0.9
0.005-0.05
N.J
(300)
(2500)
*.b
(1.8)
(0.009-0.1)
\.
I
H
oo
Per Mg (ton) of gray iron produced per hour (capacity).
N.A. - Not available.
Depends on scrap and lead content of the charge.
-------
weight percent of.lead in cupola particulate emissions, with
Q
an average of 1.2 percent. Another study reported a concen-
Q
tration of 2.6 to 3.4 weight percent lead in the emissions.
One investigator indicated a lead content of 1.2 to 5.7 per-
cent, with an average of 4.3 percent. Tests on a Los
Angeles cupola operation showed that 17 percent of the parti-
culate emissions was lead, probably attributable to a high
percentage of scrap metal in the charge.
Apparently, lead content of dust emissions vary from
0.5 to 5.5 percent or higher. The average lead content of
emissions from all foundry melting furnaces is taken as 3.0
percent. Emissions could contain higher concentrations in
recent years because of the increase in scrap recycling and
processing.
Table 4-33 presents particulate and lead emission
factors developed for the three furnaces, total annual
emissions based on the annual production rates, and estimates
of the degree of control for each process. A total of 1.079
Gg of lead (1192 tons) was emitted by gray iron foundry
operations in 1975.
4.5.1.3 Fugitive Emissions
Figure 4-34 shows a process flow diagram for a gray iron
foundry operation with the potential fugitive particulate
emissions encircled and numbered. Some of the potential
uncontrolled fugitive emission sources are the charging and
tapping of the furnaces, the various types of furnaces, and
the molding, pouring, and grinding of the iron castings.
4-182
-------
Table 4-33. LEAD EMISSION FACTORS AND ANNUAL LEAD EMISSIONS
FOR THE GRAY IRON FOUNDRY INDUSTRY
Furnace
Cupola
Reverberatory
Electric
Emission factors
Particulate3
g/kg
8.5
1.0
0.75
Ib/ton
17
2.0
1.5
Leadb
g/kg
0.3
0.035
0.026
Ib/ton
0.6
0.07
0.05
1975 throughput1
Tg
12.4
1.09
4.26
106 tons
13.7
1.20
4.70
Total emissions
£«
Lead emissions
Mg
950
33
96
1079
tons
1050
36
106
1192
oo
(jj
Based on throughput rate.
\~\ o
Based on production rate (85 percent product yield) and 3 percent lead in particulate.
Q
Based on 70 percent lead control on cupolas and no control on reverberatory and electric
furnaces.10 Calculated from particulate emission factors and 3 percent lead content.
-------
/RAW MATERIAL STORAGEN
{SCRAP METAL, METAL
INGOTS, ALLOYING AGENT.
FLUX, COKE. ETC.)
~1 *~~
CHARGING
PREHEATING
3A
CRUCIBLE FURNACE
SA
\
OPEN HEARTH
FURNACE
7A
POT FURNACE
2A
CUPOLA FURNACE
4A
ELECTRIC ARC
FURNACE
8A
6
ELECTRIC
INDUCTION
FURNACE
IA
REVERSERATORY
FURNACE
CORE\STORAGE /CORE>
SAND \ S BINDER
Figure 4-34. Process flow diagram for foundries showing
potential industrial process fugitive
particulate emission points.
4-184
-------
The largest potential sources of fugitive emissions in foundry
operations include the various types of furnaces, especially
the cupola.
The composition and particle size of dusts from various
foundry operations will vary considerably. Much of the
information on characteristics is for the stack emissions, and
Table 4-34 summarizes the information assuming fugitive emissions
are similar in characteristics. Significant lead fugitive
emissions are found in the cupola furnace dust. Fumes from
all the types of furnaces are extremely fine, and data indicate
that 90 to 95 percent of the emissions are below 0.5 ym in size.
Typical control technology for fugitive emissions consists
of capture by hoods or enclosing the building and venting the
emissions to a fabric filter.
4.5.1.4 Control Techniques - Fabric filters and wet scrubbers
are widely used on cupola operations; a few ESP's are used
also. Table 4-35 indicates performance of various control
systems on cupola operations.
A. Gas Removal: Gas is removed from cupola operations
chiefly by two methods. (1) Gases can be removed above the
charge door; in this process, however, large amounts of air
that are drawn into the charge door must pass through the
gas cleaning equipment, resulting in increased size require-
ment and higher costs; and (2) For larger cupolas, gases are
commonly withdrawn through off-takes well below the charging
4-185
-------
Table 4-34. EMISSION CHARACTERISTICS FOR
VARIOUS FOUNDRY OPERATIONS
Foundry operation
Type
Particle size (ym)
Raw material storage
and charge makeup
Melting
Cupola furnace
Electric furnace
Reverbcratory furnace
Inoculation
Molding
Pour ing
Shakeou t
Clean!nq
G r i n d i n (!
Sand storage
Sand handling
Screening', mixing
Sand drying and
reclamation
Co r o s a n d s to r a g-e
C'ore making
Coke dust
Limestone and
sand dust
Fly ash
Coke breeze
Metallic oxides
Metallic oxides
Metallic oxides
Fly ash
Metal oxides
Sand
Metallic oxides
Sand fines, dust
Dust
Metal dust
Sand fines
Abrasives
Fines
Fines
F i n e s
Dust
S a n d
Sand
fines
fines,
Fine to coarse
30 to 1,000
8 to 20
Fine to coarse
up to 0.7
up to 0.7
up to 0.7
8 to 20
up to 0.7
Coarse
Fine to medium
50?, - 2 to 15
50?. - 2 to 15
above 7
Fine to medium
50?, - 2 to 7
50?3
5 On
50 o
50?-,
2 to 15
2 to 15
2 to 15
2 to 15
dust
Fine
Fine to medium
4-186
-------
Table 4-35,
DUST AND FUME EMISSIONS FROM GRAY IRON CUPOLAS"
I
M
00
Test No.
Cupola data
Inside diameter, in.
Tuyere air, scfm
Iron -coke ratio
ProccsSjWt, Ib/hr
Stack gas data
Volume, scfm
Temperature, °F
coz, %
02, %
CO. %
N'2. %
Dust and fume data
Type of control
equipment
Concentration, gr/scf
Inlet
Outlet
Dust emission, Ib/hr
Inlet
Outlet
Control efficiency, %
Particle size, wt %
0 to 5 H
5 to 10 |i
10 to 20 (i
20 to 44 |i
> 44 (i
Specific gravity
1
60
-
7/1
8,200
8, 300
1,085
-
-
-
-
None
-
0. 913
-
65
-
18. 1
6.8
12. 8
32. 9
29. 3
3. 34
2
37
1, 950
6. 66/1
3, 380
5, 520
1, 400
12. 3
-
-
-
None
-
1. 32
-
62.4
-
17. 2
8. 5
10. 1
17. 3
46.9
2.78
3
63
7, 500
10. 1/1
39, 100
30, 500
213
2.8
-
-
-
None
-
0. 413
-
108
-
23.6
4. 5
4.8
9. 5
57. 9
4
56
-
6. 5/1
Z4.650
17,700
210
4. 7
12. 7
0
67. 5
Baghouse
1. 33
0. 051
197
7. 7
96
25. 8
6. 3
2. 2
10. Oa
55. 7b
5
42
-
9.2/1
14, 000
20, 300
430
5.2
11.8
o'. i
67. 3
Elec precip
afterburner
2. 973
0. 0359
184.7
6.24
96.6
-
-
_
_
_
6
60
-
9. 6/1
36, 900
21, 000
222
-
-
-
-
f? aghouse
0. 392
0. 0456
70. 6
8. 2
88. 4
-
-
_
.
_
7
48
-
7.4/1
16,800
8, 430
482
-
-
-
-
Elec Precip
1. 522
0. 186
110
13. 2
87. 7
_
_
_
.
_
aFrom 20 to 50 (JL.
bGrcater than 50 fi.
-------
door. This process reduces infiltration air to less than 10
percent of the blast volume, but requires precision controls
to prevent explosion. Figure 4-35 illustrates these two
methods.
B. Gas Cooling: It is common to pass the hot gases in a
refractory-lined duct through a spray chamber located near
the cupola. In the spray chamber, the gases are quenched to
a temperature compatible with the control system in use.
Cooling by radiation, conduction, and convection may also be
14
accomplished with U-tube coolers.
C. Fabric Filters: Silicon-coated fiberglass fabric
filters are used on many cupolas, primarily because of their
high temperature resistance. Fabric filters are also common
on electric and reverberatory furnaces when emission control
is required and provided. Figure 4-36 shows a modern
baghouse installation on a cupola. Use of fabrics with low
temperature resistance has been successful because conden-
sation of sulfuric acid mist presents a serious corrosion
problem. Gas temperatures ranging from 650 to 1040°C (1200
to 1900 F) can be expected when secondary combustion takes
place within the stack, and from 150 to 540°C (300 to 1000°F)
when no combustion takes place. Because fluorspar is some-
times used as an additive, the fluoride liberated can also
cause corrosion. In these cases, Nomex bags are used and
temperatures can be reduced to 204°C (400°F).14
4-180
-------
CAP
i
M
CO
OFFTAKE
DILUTION AIR
CHARGE HOLE
OFFTAKE
CUPOLA
GASES
CHARGE
HOLE
CUPOLA
GASES
Figure 4-35. Method of capturing exhaust gases from cupola operations
left, above charge door off-take; right, below charge door off-take.14
(Courtesy of the Mcllvaine Company, Northbrook, IL)
-------
O
1. COUNTERWEIGHT CAP
2. AIR CYLINDER
3- BRICK LINED STACK
4. COMBUSTION BLOWER
-!
5. GAS TRAIN
6. THERMOCOUPLE
7. "T" SECTION TAKE-OFF
8. AFTERBURNER
9. CHARGE OPENING
10. CROSSOVER AND DOWNCOMER
11. SPRAY HEADERS
SPRAY NOZZLES
13.
14.
15.
16.
17.
18.
19.
20.
21.
AUTOMATIC VALVE MANIFOLD
LOW PRESSURE WATER
WATER BOOSTER PUMP
SLIDE GATE VALVE
ISOLATION JOINT
DAMPER DRIVE ASSEMBLY
REVERSE AIR DUCT
SHAKER FRAME
SHAKER DRIVE
22. BAG («0 PER SECTION/HOPPER)
23. HOPPER
24. MAIN AIR DAMPER
25. AIR CYLINDER
26. SCREW CONVEYOR i DISCHARGE
27. PROGRAM TIMER
28. COMPRESSED AIR
29. AIR VALVE MANIFOLD
\' \ 'I ^-e-'
^) J^dt __14
CUPOLA
QUENCHER
FAN
INLET BOX
DRIVE ASSEMBLY
BACHOUSE
SECTION
Figure 4-36. Fabric filter control system on a gray iron cupola.
(Courtesy of The Mcllvaine Company, Northbrook, IL)
14
-------
Table 4-36 indicates fabric filter performance on
electric arc furnaces. The facility tested consisted of
three furnaces and produced about 14.1 Mg/h (15.5 tph) of
gray iron per heat. (A "heat" encompasses the time from the
beginning of the charging to the end of the tapping of the
molten material). These are ducted to a suction baghouse
with a filtering velocity of 5.0 cm/s (2.54 fpm). Filter
media is Dacron and withstands temperatures of up to 135°C
(275°F). According to EPA tests on well-controlled electric
arc furnaces, the emissions from properly designed and
operated fabric filters generally range from 0.075 to 0.17
kg/Mg gray iron (0.15 to 0.35 Ib/ton) or 13 to 24 mg/m3
(0.0058 to 0.0106 gr/scf).
4-191
-------
Table 4-36. FABRIC FILTER PERFORMANCE TEST RESULTS ON A
GRAY IRON ELECTRIC ARC FURNACE3
Furnace capacity, Mg
_ tons
Flow rate, m /s
acfm
Temperature, °C
OF
Moisture, % v
Emissions
g/m (gr/dscf)
kg/hr (Ib/hr)
kg/Mg (Ib/ton)
Inlet
7.05
15.5
42.8
90,710
86
187
2.4
0.76 (0.33)
88.6 (195)
3.2 (6.3)
Outlet
7.05
15.5
46.9
99,350
83
182
2.3
0.013 (0.0058)
1.84 (4.05)
0.073 (0.146)
Obtained from U.S. EPA, Emission Test Branch, Research
Triangle Park, N.C. For Background Information for New
Source Performance Standards for Gray Iron Electric Arc
Furnaces.
4-192
-------
D. Electrostatic Precipitators: Application of ESP's on
cupola operations in the United States has been limited.
The major operational problems are associated with variabi-
lity of emissions and flow rates, small particle sizes, high
particle resistivity, and explosion potential during upset
conditions due to a high CO content.
Complete combustion of CO to C02 is required prior to
gas cleaning by an ESP to prevent fire or explosion. After
combustion, the gases are generally cooled to 150 to 204°C
(300 to 400°F) by evaporative methods to reduce electrical
resistivity.
A typical ESP installation for a cupola with 9.07 Mg
per hour melt rate (10 tph) exhausting 8.0 to 9.5 m /s
(17,000 to 20,000 acfm) required 1670 m of plate area
2
(18,000 ft ) to maintain a collection efficiency of 90 to 97
percent. Stainless steel construction was used to minimize
corrosion. Drift velocities were 9 to 18 cm/s (0.3 to 0.6
* » 15
fps) .
European ESP installations on hot blast cupolas have
rarely achieved over 99 percent efficiency with outlet grain
loadings ranging from 0.05 to 0.16 g/m (0.02 to 0.07
gr/dscf).
4-193
-------
E. Wet Collectors: Various types of wet collectors are widely
used for control of cupola emissions. These include the con-
ventional and double wet-cap, low-energy (AP = 1.5 kPa or 6 in.
H20) scrubbers, and high-energy (AP = 7.5-17.4 kPa or 30-70 in.
H90) scrubbers. The most recent installations of wet collectors
have been of the high-energy type (venturi or packed-bed) ,
which are adequate to meet state regulations.
Several factors determine the pressure drop requirements
of the scrubbers: 1. Temperature of the melt zone. Higher
temperatures volatilize and oxidize metallic components,
yielding submicron particles. 2. Scrap quality. High scrap
content increases grain loading. 3. Lining. Unlined cupolas
generate particles of larger size. 4. Oxygen enrichment.
Higher emission concentrations result, since the oxygen used
for combustion does not carry with it the inert volume of
nitrogen. 5. Air preheating. Hot blast tends to increase
pressure drop requirements. Figure 4-37 shows emissions
versus orifice pressure drop.
The combination of high temperature with corrosive
gases and dusts creates a potential for high maintenance
requirements. Stainless steel scrubber construction has
been satisfactory; carbon steel may be used where pH control
is provided. Generally, systems are constructed of 316-
stainless steel upstream of the scrubber and carbon steel
4-194
-------
7.0
6.0
5.0
CQ
o,
I—I
«/} A ft
q'u
UJ!
-------
downstream. Auxiliary equipment, including fans and pumps, is
constructed of abrasion-resistant cast iron. Figure 4-38
illustrates a venturi scrubber on a cupola furnace.
cross section
SCRUBBER
jS~*\. CLUMO Ml
-^•^M| 10 tTUOIFHEU
Figure 4-38. Venturi gas scrubbing system
installed on a foundry cupola.16
(Courtesy of General Motors Corporation, Detroit, Michigan)
4-196
-------
4.5.1.5 Control Costs - A gray iron cupola with a produc-
tion capacity of 13.6 Mg/h (15 tph) is considered the model
size to determine control costs. The cupola exhausts 36.4
m3/s at 980°C (77,000 acfm at 1800°F), and particulate emis-
sions are 140 kg/h (306 Ib/hr) with up to six percent lead.
The gases enter a quench tower, where they are cooled to
93°C (200°F) before they enter a venturi scrubber and entrain-
ment separator (AP = 15 kPa [60 in. W.G.] and 95% efficiency).
A fan rated at 17.8 m /s (37,800 acfm) at a system pressure
drop of 16 kPa (65 in. H2O) is also provided. This level of
control will permit compliance with an average state particu-
late limitation of 12.7 kg/h (28 Ib/hr).
Capital costs are estimated at $1.12 million, including
collector, quench tower, separator, fan system, hold tanks,
pumps, and ductwork.
Annualized costs are estimated at $565,000, including
utilities, labor, maintenance, overhead, fixed costs (with
capital recovery), sludge disposal, and water treatment.
Annual operation time is assumed at 6000 hours and annual
labor required is assumed at 6000 hours.
Capital and annualized costs are expressed below in
terms of exhaust volume, annual labor hours and annual
production:
See Section 2.9 and Appendix B for discussion of cost analyses
Detailed cost studies are available from EPA upon request.
4-1.97
-------
S.I, units
^ n f\
Capital, $ = 1.3 x 10 V
Annualized, $ = 3250V + 19.6H + 35,200V°'6 + 0.31M
V = m3/s @ 980°C
H = annual labor hours
M = annual production, Mg/yr
12 < V < 110
range
English units
Capital, $ = 1310 Q°'6
Annualized, $ = 1.53Q + 19.6H + 356Q0'6 + 0.28P
Q = acfm @ 1800°F
H = annual labor hours
P = annual production, TPY
26,000 < V < 230,000
range
4.5.1.6 Impacts
A. Emission Reduction
Reduction in particulate emissions from cupola opera-
tions by air pollution controls will be about 8.0 g/kg of
gray iron (16 Ib/tonl. The particulate lead content could
range from 0.5 to 17 percent by weight depending on operating
factors.
4-198
-------
B. Energy Consumption
The energy from electricity and natural gas required to
produce cupola gray iron is about 0.7 GJ/Mg (0.7 MM Btu/ton)
of product. The energy requirements for the model cupola
venturi scrubber (see previous section) are 0.14 GJ/Mg (0.14
MM Btu/ton), representing a 20 percent increase.
C. Wastewater Generation
Only cooling water is required for cupola operations.
No data was obtained to estimate total plant or cupola water
usage rates. The wastewater generated for the model cupola
venturi system is calculated at (40 gal/ton) of product.
This could be a significant increase in wastewater, however
this water can be settled and recycled or discharged.
D. Solid Waste Generation
The solid waste generated by cupola operations is about
1.0 kg/Mg (700 Ib/ton) of product some of which may be mainly
recycled. The dry solids collected by the venturi system on
the model cupola amounts to about 8.0 kg/mg (16 Ib/ton) which
is also recycled. The increase is roughly 8 percent, however,
no impact is expected since it is mainly recycled.
4-199
-------
4.5.2 Iron and Steel Industry
Six processes in iron and steel manufacture are emitters
of lead: 1) sintering, 2) coking, 3) blast furnaces, 4)
open-hearth furnaces, 5) basic oxygen furnaces, and 6)
electric arc furnaces. The 1975 production rates for these
processes are presented in Table 4-37.
Table 4-37. PRODUCTION FOR IRON AND STEEL
-I Q
INDUSTRY IN 1975
Process
Sintering
Coking
Blast furnace
Basic oxygen
Open hearth
Electric arc
1975 production
Tg
27.94
43.83
72.45
65.12
20.10
20.57
106 tons
30.83
48.32
79.92
71.80
22.16
22.68
A total of 605 Mg of lead (667 tons) was estimated to be
emitted to the atmosphere in 1975 by the iron and steel
industry from particulates containing lead components,
not including fugitive emissions.
4.5.2.1 Processes - Descriptions and control information
given in references 19 and 21 are summarized in the following
paragraphs.
4-200
-------
A. Raw Material Preparation: The major raw materials
required to make pig iron (or "hot metal" as it is called in
its molten state) are iron ore, sinter, pellets, coke,
limestone, fluxes and air. Some lump iron ore is used for
making hot metal, but about 70 percent of the metallics
charged to American blast furnaces are agglomerated products
19
such as pellets and sinter. Pellets are made at the mine
site by grinding the ore to a very small size (usually less
than 325 mesh), adding a binder, and then forming the ore
i:,t.j small balls or pellets, which are subsequently hardened
by heating or ignition. After h".; icier,ing, the pellets are
shipped to the steel plants for use directly in the blast
19
furnace. Lead is a trace mineral in the iron ore.
B. Sintering: Sintering was initially developed to
recover and convert to a useful form the ore fi.ies, blast-
furnace flue dust, mill scale, and other Iron-bearing mate-
rials that could not be used directly as charge to a blast
19
furnace. These materials are mixed with fine coke and
fired on a travelling grate. This firing produces a sinter,
or fused mass of material, which is cool-'"1, broken up and
charged into the blast furnace. The sinter plant area has
many points of dust emissions because of the fine materials
handled. Lead is present primarily in the ore fines.
C. Coking: Coke is the major fuel and reducing agent used
to make hot metal in blast furnaces. Metallurgical coals
4-201
-------
received from the mines are crushed to size and blended with
other coals, and then charged into coke ovens for conversion
to coke. Conversion is achieved by subjecting the coal to
indirect heating in long, thin ovens, for periods of 14.5 to
17 hours. On completion of the coking cycle, the coke is
pushed from the ovens into a quench car, which carries it to
a quenching tower where the incandescent coke is quenched by
water sprays. The coke is then crushed and screened prior
19
to its use in the blast furnace. An average of over 640
kg of coke is required for every Mg of iron (1280 Ib/ton)
21
produced in blast furnaces. Lead is a trace mineral in
the coal (see section 3.2).
D. Blast Furnace: The prepared materials (coke, iron ore,
scrap pellets, sinter, and flux), collectively called the
"burden", are placed in separate transient storage bins in
the blast-furnace stockhouse. They are withdrawn in weighed
fractions into a scale car and charged into the top of the
blast furnace via a skip hoist or, in the newest blast
furnaces, by continuous conveyor belts. Figure 4-39
illustrates material flow and operations within a blast
furnace pig iron plant.
The heat energy required for chemical reactions between
the iron ore, pellets, sinter, and flux is supplied by
blowing air, preheated to temperatures of 810 to 1090°C
4-202
-------
I
K)
O
U)
CAR ORE AUO
LIMESTONE
ORE OR LIME- TROUGH
STONE BOAT
AND DOCK
BOILER HOUSE
LEGEND
• HISCflUHfWS Kit WOHl
• eno-msr an
PIG
IRON
OCOMOTIVE CAR CAR PIG CASTING TILTIN3 TO HOT' HOT METAL !'
CRANE MACHINE DEVICE OPEN HEARTH METAl METAL !
OR MIXER LADLE I
BASIC OXYGEN -_.„ rSof*J
FiiBNdr.F* GRAB ! HOI *
---- tAS! IWIXC US
— « — » smit
mrsut
fuiEtasr
auicf
sum
TO CEMENT PLANT
SLAG THOTSLAO
SLAG GRANULATING
TANK
c±i
DRY SLAG PIT
SLAG
LADLE
TO SLA6 BREAKER
OR SLAG DUMP
SOAKING PIT
REHEATING FURNACE
Figure 4-39. Flow diagram depicting the principal units and auxiliaries in modern
blast-furnace plant, and showing the steps in the manufacture of pig iron from receipt
of raw materials to disposal of pig iron and slag, as well as the methods for utilizing
the furnace gases. 21
(Copyright 1971 by U.S. Steel Corporation)
-------
(1400 to 2000°F), into the bottom of the blast furnace via
blowpipes known as "tuyeres". The combustion of coke also
maintains the pig iron in a molten state and at a tempera-
ture such that the iron can be removed from the furnace by
"casting". The coke in the combustion zone at the tuyeres
does not burn to carbon dioxide. Because of the high temper-
ature, about 1930 to 1980°C (3500 to 3600°F), and the pre-
sence of the large amount of carbon in the form of coke,
carbon monoxide is formed and passes on up through the solid
burden, where it takes part in some of the chemical re-
actions necessary to produce metallic iron. The excess of
carbon monoxide (diluted with carbon dioxide, nitrogen, and
moisture) passes off the top of the blast furnace and is
collected for use as fuel to heat the air blown into the
19
blast furnace and for other in-plant heating purposes. " A
blast furnace plant is shown in Figure 4-40.
The hot metal produced in the blast furnace and the
liquid slag (which is a fused mixture of the flux and im-
purities removed from the ore, pellets, sinter, and coke)
are removed periodically from the blast furnace. The hot
metal is "cast", while the slag is said to be "flushed".
Hot metal is cast and transferred to the steelmaking plant.
Slag is disposed of at a dump via a ladle, or it may be
granulated by air or water cooling to produce an aggregate
that is sold.
4-204
-------
A. Ore bridge
B. Ore transfer car
C. Ore storage yard
D. Stockhouse
D-l Ore and limestone bins
D-2 Coke bin
D-3 Scale car
E. Skip
F. Coke dust recovery chute
G. Freight car
H. Skip and bell hoist
I. Slap bridge
J. Blast furnace
J-l Bkeder valve
J-2 Gas uptake
J-3 Receiving hopper
}A Distributor
K.
L.
M.
N.
O.
Legend
J-5 Small bell
J-6 Large bell
J-7 Stock line
J-8 Stack
J-9 Bosh
J-10 Tuyeres
J-ll Slag notch
J-12 Hearth
J-13 Bustle pipe
J-14 Iron notch
Slag ladle
Cast house
L-l Iron trough
L-2 Slag skimmer
L-3 Iron runner
Hot-metal ladle
Flue dust car
Dust catcher
P. Downcoiner
Q. Hot blast line to furnace
R. Gas washer
R-l Sludge line to thickener
R-2 Spray washer
R-3 Electrical precipitator
S. Gas offtake to stove burner
T. Hot blast connection from stove
U. Stove
U-l Gas burner
U-2 Combustion chamber
U-3 Checker chamber
V. Exhaust gas line to stack
W. Cold blast line from blower
X. Surplus gas line
Y. Stock—Iron ore. coke, limestone
Z. Jib boom crane
Figure 4-40. Idealized cross-section of a typical modern blast-furnace
plant. Details may vary from plant to plant.
(Copyright 1971 by U.S. Steel Corporation)
4 205
-------
Although almost all pig iron in the United States is
made in blast furnaces, another process is "direct reduc-
tion", a name applied loosely to any method that bypasses
the blast furnace. Reduction of the iron ore to metal is
conducted entirely in the solid state, although the metallic
iron might subsequently be melted. Direct-reduction pro-
cesses appear in many variations, but all use some form of
carbon and/or some form of hydrogen as fuel and reducing
agent. Carbon can be supplied as coal, coke, or other
hydrocarbons. Carbon monoxide is one of the useful forms of
carbon for this purpose. Hydrogen is supplied sometimes
from reformed natural gas (when it often appears in a mix-
ture with carbon monoxide) or from coke-oven gas. Regard-
less of the process, the product usually is a spongy or
powdered form of metallic iron (still mixed with gangue from
the iron ore), which then is intended for charging directly
19
into electric or blast furnaces.
E. Open Hearth: The open-hearth furnace is a rectangular
furnace with a comparatively shallow hearth for containing
and processing the steel. An open-hearth furnace is shown
in Figures 4-41 and 4-42. Scrap, flux, and hot metal are
charged into the furnace via doors located in the front of
the furnace. The charge materials are heated with various
fuels such as oil, tar, natural gas, and combinations of
4-206
-------
STAC
TAPPING
SPOUT
FORCED AIR
INLET VALVE
END VAIL
REHOVED
CHECKER FLUE
REGENERATIVE CHAHBER
HTH ROOF AND SIDE
VALL REMOVED
Figure 4-41. This diagram illustrates the principal parts of an
open-hearth furnace (with silica roof) sectioned to show as much as
possible of the interior. The heavy curved arrows indicate the direction
of the flow of preheated air, flame, and waste gases when liquid fuel is
fired through a burner in the trench at the right end of the furnace.
The five doors shown are in the front wall of the furnace, and the checker
chambers extend under the charging floor, which is not shown. When
reversal of firing takes place, the function of the uptake is reversed,
and it becomes the downtake. 21
(Copyright 1971 by United States Steel Corporation)
4-207
-------
BURNER
BURNER ARCH
CHARGING FLOOR
LEVEL
CHILL
ROOF
v-(BASIC) (SILICA)
7
KNUCKLE
BATH
IIUL y-bAin /-nc.A
BOTTOM
BURNER
ENDWALL
CHARGING FLOOR
LEVEL
h of T .Dia9r™atlc se'ctxon (not to scale) along the
length of a liquid-fuel fired open-hearth furnace, giving
nomenclature of major parts. Left half of roof simulates
^rhChC°nfrUCtl°n; rlght half' Silica construction. Burner
arch has been omitted from design at right.21
(Copyright 1971 by United States Steel Corporation)
4-208
-------
these. The older steelmaking technology used iron ore and
air to supply the necessary oxygen, while the newer tech-
nology makes use of gaseous oxygen introduced into the
molten bath through one or more water-cooled lances. Open-
hearth steelmaking requires comparatively long time periods,
ranging from 8 to 10 hours in operations not using oxygen
lancing to 4 to 5 hours in operations using oxygen lancing.
F. Basic Oxygen Furnace: The basic oxygen furnace (EOF)
is a pear-shaped vessel that contains the charge materials
required to make steel. As in the open-hearth process, the
major materials are hot metal and scrap. In the basic
oxygen process, no external heat is supplied to reduce the
contents of carbon, silicon, and manganese. Gaseous oxygen
is blown onto the surface of the molten charge at a very
high rate, and the heat generated by the oxidation of the
elements is sufficient to carry the process to completion
and produce steel. A typical EOF is shown in Figure 4-43.
G. Electric Arc Furnaces: The heat necessary to produce
steel in an electric-arc furnace is supplied as electrical
energy to the charge material which in the majority of cases
is scrap steel. Several steelmaking plants in the United
States are known to use hot metal as part of the charge in
large electric furnaces. Oxygen (in the form of ore, mill-
scale, or gaseous oxygen) to lower the carbon content is
4-209
-------
CONVEYOR
FROM
RAW-MATERIALS
STORAGE
BUILDING
I
to
STORAGE
FLOOR
WEIGHING
FLOOR
BATCHING
FLOOR
SERVICE
FLOOR ~
OPERATING
FLOOR *
GROUND
L6VEL-
CONVEYOR
BATCHING HOPPER
LADLE ADDITIVE
TRANSFER CAR
Figure 4-43. Schematic elevation showing the principal operating units of
the basic oxygen process steelmaking shop.
21
(Copyright 1971 by United States Steel Corporation)
-------
used to produce steel. The use of gaseous oxygen is by far
the more prevalent method. Most stainless and alloy steels
are made in electric furnaces. In recent years, the in-
crease in furnace size, combined with higher powered trans-
formers and a greater availability of scrap, has made electric-
furnace steelmaking of the plain-carbon, high-tonnage steels
19
competitive in cost with open hearth and EOF steelmaking.
A cross-section of an electric arc furnace is shown in
Figure 4-44. Lead contained in the scrap in the form of
leaded steel, lead coated steel, or lead debris is the main
source of lead emissions from this furnace.
In all steelmaking practices, the refined steel is
tapped from the furnace into ladles, after which it is
transported to an adjacent area of the steel plant where it
is teemed into ingots, cast directly into continuous casting
machines, or teemed into pressure-casting molds for conver-
19
sion to semifinished products.
4.5.2.2 Emissions
A. Sintering: Sintering is a source of significant
atmospheric emissions. Particulate emissions are estimated
to be about 11 g/kg of sinter (22 Ib/ton) at the discharge
vents and 10 g/kg of sinter (20 Ib/ton) at the windbox.
Combustion is maintained at a temperature of about 1300
i p
to 1500°C (2370 to 2730°F). The process emits not only
4-211
-------
XTROOES
WATER-COOLED
ROOF RING-
SILICA BRICK
HIGH-ALUMINA
•=IRICK
METAL-ENCASED
DIRECT-BONDED
MAGNESITt-CHROME
BRICK
SHOWS AN ACID LINING
SHOWS A BASIC LINING
Figure 4-44. Schematic cross-section of a Heroult electric-
arc furnace with a dish-bottom shell and stadium-type sub-
hearth construction, indicating typical refractories employed
in (left) an acid lining and (right) a basic lining.
Although only two electrodes are shown in this section,
furnaces of this type (which operate on three-phase current)
have three electrodes. 1
(Copyright 1971 United States Steel Corporation)
4-212
-------
sulfur oxides (30 to 40 percent of the sulfur in the charge
is liberated), but also other volatile constituents. Sulfur
content of the gases could be as high as 2000 ppm but is
generally less than 200 ppm. Hydrocarbon fumes may be
evolved if oily scrap is used in preparation of the sinter
. 20
mix.
In addition to sinter machines and sinter screens, all
conveyor transfer points, loading points, chutes, and bins
handling sinter are potential sources of fugitive dust.
Many industries control the dust at these points by use of
a chemical wetting agent mixed with water. Table
summarizes the exhaust gas characteristics associated with
the sintering process.
Based on a lead content in the particulate of 320
23
ppm, the lead emission factor is 6.7 mg Pb/kg of sinter
(0.013 Ib/ton). Based on a 90 percent level of control and
27.9 Tg of sinter (3.08 x 10 tons) produced in 1975, lead
emissions were 18 Mg (20 tons).
B. Coking: Metallurgical coals of low ash content, low
sulfur content, and suitable coking properties are used in
the coking operation. The analytical properties of the coal
have no apparent effects on the quantities of emission
during charging. Dust is evolved when the larry car is
filled with coal and a predetermined volume of coal is
charged to the larry car hoppers. Charging the coal to
4-213
-------
Table 4-38. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM SINTERING MACHINES
Parameters
Gas flow rate
Temperature
Moisture content
Grain loading
Particle size
Lead content
of particulate
SO- content
Emission
f actors*3
° particulate
0 lead
Standard
international
units
0.8-1.0 m3/s-Mg-
h~l sinter
200°C
4.5-10% v
2.2 g/m3
98% < 45 ym
320 ppm (wt)
< 200 ppm v
21 g/kg sinter
6 . 7 mg/kg
sinter
English
units
1600-2000
scfm/tph sinter
392°F
4.5-10% v
1.0 gr/scf
98% < 45 ym
320 ppm (wt)
< 200 ppm v
42 Ib/ton sinter
0.013 Ib/ton
sinter
References
9
20
20
20
23
20
20, 22
Includes windbox and discharge vent gases (90% v) and
product cooler gases (10% v).
Includes emissions from windbox and discharge vents.
4-214
-------
ovens also results in high dust emissions, accounting for 60
20
to 70 percent of total emissions from oven batteries.
Emissions from oven charging are as follows: particu-
late, 0.75 g/kg (1.5 Ib/ton); sulfur dioxide, 0.01 g/kg
(0.02 Ib/ton); carbon monoxide, 0.3 g/kg (0.6 Ib/ton);
hydrocarbons, 1.25 g/kg (2.5 Ib/ton); nitrogen oxides, 0.015
g/kg (0.03 Ib/ton); and ammonia 0.01 g/kg (0.02 Ib/ton).
24
These values are based on the rate of material throughput.
Maximum temperature attained at the base of the heating
2
flue of the oven may be as high as 1480°C (2700°F). In
the oven, coking temperatures are between 1100 to 1150°C
(2000 to 2100°F). Limited emissions can occur around door
seals and other points of leakage, but with adequate main-
tenance these emissions can be kept to a minimum.
Coke-pushing emissions vary with the degree of coking.
Well-coked coal will smoke very little when pushed into the
quench car, whereas poorly coked "green" coke will cause
20
excessive smoke. Particulate emissions for pushing opera-
tions amount to about 0.3 g/kg of coal charged (0.6 Ib/ton).
Quenching results in entrainment of the fine coke
breeze in the steam plume which is formed during the pushing
operation as a result of water being flash-evaporated on the
coke. The average weight of particulates emitted during
a 2-minute quench cycle at one plant was calculated to be
4-215
-------
2.7 kg (6.0 Ib). These emissions could be reduced to less
20
than 0.4 kg (0.88 Ib) by installation of baffles.
Total particulate emissions from unloading, charging,
coking cycle, discharging, and quenching amount to 1.75 g/kg
24
of coal charged (3.5 Ib/ton) with no controls. Measure-
ments indicate that lead contents are about 0.01 percent of
25
particulate emissions from pushing operations. Nationwide
lead emissions from coking operations in 1975 were 11 Mg (12
tons). This estimate is based on a particulate emission
factor of 1.75 g/kg of coal (3.5 Ib/ton), 0.01 percent lead
concentration in the dust, and a 1975 coal consumption of 60
Tg (6.6 x 107 ton),26
C. Blast Furnace Emissions; The blast furnace operates at
about 1540°C (2804°F). Many furnaces now operate at-pres-
sures of about 68.9 kPa (10 psi). The pressure range in
newer plants is 101 kPa (14.7 psi) to 431 kPa (62.6 psi). 20
A high degree of particulate emission control is
necessary to prevent plugging of the stoves (heat exchangers)
Without controls, dust emissions are 75 g/kg iron (150
22
Ib/ton). Particulates are also emitted during each tap,
but the fumes enter the atmosphere through the open sides of
the cast house. Blast furnace slips, which create emissions
that bypass the control devices, rarely occur.^ Table 4-39
summarizes typical exhaust gas characteristics for blast
furnace operations.
4-216
-------
Table 4-39. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM IRON BLAST FURNACES
Parameters
Gas flow rate
Temperature
Moisture content
Grain loading
Lead content
of particulate
Emission
factors
0 particulate
0 lead
Standard
international
units
0.9-1.3 m3/s-Mg-
h~l iron
180-280°C
2% v
27.5 g/m3
830 ppm (wt)
75 g/kg iron
62 mg/kg iron
English
units
1800-2500
acfm/tph iron
360-540°F
2% v
12 gr/scf
830 ppm (wt)
150 Ib/ton iron
0.124 Ib/ton iron
References
20
20
20
20
23
22
4-217
-------
Based on a lead content in the particulate of 830
ppm,23 the lead emission factor is 62 mg Pb/kg of iron
produced (0.124 Ib/ton). Based on a 98 percent level of
control and 72.5 Tg of iron produced (7.99 x 10 tons) in
18
1975, lead emissions from blast furnace operation were 91
Mg (100 tons).
D. Open-Hearth Furnace; The tapping temperature of steel
in an open-hearth steel furnace is about 1595°C (2903°F),
20
varying with composition and grade of steel.
Emissions from open-hearth operations include parti-
culates and fluorides. Fluoride emission rates depend on
the fluorspar content of the iron. Uncontrolled particulate
emissions from a furnace without oxygen lancing are about
4.2 g/kg of product (8.4 Ib/ton); with oxygen lancing,
emissions range from 4.7 to 11.0 g/kg (9.4 to 22 Ib/ton) and
72
average about 8.7 g/kg (17.6 Ib/ton).
Table 4-40 presents characteristics of open-hearth
exhaust gas. Lead emissions from open hearths range from
0.05 to 2.2 percent of total particulate emissions, averag-
19 ?"? ?R
ing about 0.8 percent. ' ' Assuming predominately
oxygen lancing operations, the lead emission factor averages
70 mg/kg of steel (0.14 Ib/ton). With a collection effi-
ciency of about 90 percent and a steel output from open
hearths of 18.2 Tg (2.01 x 107 tons), 18 nationwide lead
emissions were 128 Mg (141 tons) in 1975.
4-218
-------
Table 4-40. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM OPEN-HEARTH STEEL FURNACES
Parameters
Gas flow rate
Temperature
Grain loading
Particle size
Lead content .
of particulate
Emission
factors
0 particulate
- with 0 lance
- no 0- lance
0 lead
Standard
international
units
1.2 m3/s-Mg-h~1
< 980°C
7-12 g/m3
50-75% < 5 ym
0. 8% w
8.7 g/kg steel
4.2 g/kg steel
70 mg/kg steel
English
units
2300 scfm/tph
< 1800°F
3-5 gr/scf
50-75% < 5 ym
0. 8% w
17.4 Ib/ton
steel
8.4 Ib/ton steel
0.14 Ib/ton
steel
References
20
20
20
19, 23, 28
22
22
Based on throughput rates.
Lead content of particulate ranges from 0.05 to 2.2 percent
with an average of 0.8% wt.
4-219
-------
E. Basic Oxygen Furnace: Operating time per melt in a
basic oxygen furnace is 50 minutes. Since the EOF process
is exothermic, no additional heat is required. Refining
occurs at approximately 2000°C (3632°F) at atmospheric
20
pressure.
Particulate emission rates are so high that all basic
oxygen units are equipped with high-efficiency particulate
control devices. About 25.5 g/kg of particulate (51 Ib/ton)
is produced, and about 0.1 g/kg of gaseous fluorides (0.2
po
Ib/ton). Most of the furnace emissions are controlled by
venturi scrubbers or electrostatic precipitators with 98
2 0
percent collection efficiency- Table 4-41 presents
characteristics of EOF exhaust gases.
Lead emissions from EOF furnaces run about 0.4 percent
23,28
of particulate emissions, giving an emission factor of
0.1 g Pb/kg (0.2 Ib/ton) of steel produced. Based on 98
percent collection efficiency and a 1975 EOF output of 65.12
7 18
Tg (7.18 x 10 tons),10 nationwide lead emissions were 130
Mg (144 tons).
F. Electric Furnace: Particulate emissions from electric
furnaces consist primarily of oxides of iron, manganese,
aluminum, and silicon. Many new electric furnace installa-
20
tions use baghouses. Uncontrolled particulate emission
rates are about 4.6 g/kg of metal (9.2 Ib/ton) without
4-220
-------
oxygen lancing and about 5.5 g/kg of metal produced (11.0 Ib/ton)
22
with oxygen lancing. Exhaust gas characteristics are presented
in Table 4-42.
Because the feed to electric furnaces normally contains
high volumes of scrap, which contributes higher lead inputs than
other furnaces receive, lead emissions may range from 0 to
5.7 percent of particulate emissions, averaging about 2.0
8 19 23 28
percent. ' ' ' Since oxygen lancing is being used more
frequently for electric furnaces, the uncontrolled lead emission
factor is 0.11 g/kg of steel produced (0.22 Ib/ton). With an
average collection efficiency of about 90 percent and a 1975
output of 20.57 Tg of steel (2.27 x 107 tons)18, total lead
emissions were 227 Mg (250 tons) from U. S. electric arc steel
production.
4.5.2.3. Fugitive Emissions
A process flow diagram for iron production is shown in
Figure 4-45 with each potential process fugitive emission
source encircled and numbered. The largest potential sources
of fugitive particulate emissions are iron ore handling and
storage. Other major potential sources are sintering operations,
blast' furnace tapping, and slips.
The characteristics and size distributions of the fugitive
emissions from various sources are assumed to be similar to the
uncontrolled exhaust emissions.
4-221
-------
LUMP IRON ORE
IRON ORE FINES LIMESTONE IRON ORE PELLETS
DUST STORAGE
'». '
PRIMARY
CLEANER
*
SECONDARY
CLEANER
FLUE GAS
(CO)
GAS CLEANING
SYSTEM
Figure 4-45. Process flow diagram for iron production
showing potential industrial process fugitive
particulate emission points.
4-222
-------
Fugitive emission can be controlled by enclosure of the
conveyor system for handling and transfer of raw materials,
by use of a fixed hood constructed around the sinter machine
discharge which can then be vented to a baghouse, and by
better operating practices and better quality of raw materials
used in the blast furnace and sintering machines.
4.5.2.4 Control Techniques - Cyclones are suitable for
collecting medium and coarse dusts, but are not suited for
very fine dusts or metallurgical fumes. Their principal
application is as precleaners for other types of control
equipment. As precleaners, cyclones are used in series with
wet scrubbers and ESP's for cleaning blast-furnace gas and
as precleaners for ESP's handling the dust and gas from a
sinter-plant wind box.
Wet scrubbers of various types have been used in the
integrated iron and steel industry for many years. In-
stallation of orifice, variable-orifice, or venturi scrub-
bers in the gas system is a practical way of obtaining
cleaner gas from modern blast furnace systems with furnace
top pressures above atmospheric. The pressure required to
achieve the necessary cleaning action was already in the
blast furnace, and little additional auxiliary equipment is
required. High-energy scrubbers are used to control emis-
sions from sinter plants and BOF's, as well as from
4-223
-------
Table 4-41 . CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM BASIC OXYGEN FURNACES
Parameters
Gas flow rate
Temperature
Grain loading
Particle size
distribution
Lead content
of particulate
Emission
factors
0 particulate
0 lead
Standard
international
units
0.8 m3/s-Mg-h~1
82-260°C
4.5-12 g/m3
0.1 to lym - 95%
0.4% (wt)
25.5 g/kg steel
0.1 g/kg steel
English
units
1500 scfm/tph
180-500°F
2-5 gr/dscf
0.1 to 1 urn - 95%
0.4% (wt)
51 Ib/ton steel
0.2 Ib/ton steel
References
20
20
20
20
23,28
?2
Based on throughput rates.
After cooling and conditioning.
4-224
-------
Table 4-42. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM ELECTRIC ARC FURNACES
Parameters
Gas flow rate
Temperature
Grain loading
Lead content
of particulate3
Emission
factors
0 particulate
- with 02 lance
- no Op lance
0 lead
Standard
international
units
2.3 m3/s-Mg-h~1
650-980°C
5-7 g/m3
2.0% wt
5.5 g/kg steel
4.6 g/kg steel
0.11 g/kg steel
English
units
4,300 scfm/tph
1200-1800°F
2-3 gr/scf
2.0% wt
11.0 Ib/ton
9.2 Ib/ton
0.22 Ib/ton
References
20
20
20
8,19,23,28
22
22
22
Lead content of particulate emissions range from 0 to 5.7
percent, with 2 percent being a typical average.
4-225
-------
blast furnaces. One of the principal advantages of high-
energy wet scrubbers is their ability to handle variable gas
19
volumes, while maintaining the required operating efficiency.
ESP's are used for removal of dust particles (primarily
iron oxide) from exhaust gases of ironmaking and steelmaking
processes. Because of the wide range of resistivities that
can be encountered, it is preferable to determine resistivi-
ties for a specific process when designing precipitator
installations. Dusts can be conditioned to reduce the
resistivities and to facilitate dust collection in the ESP.
The lower the resistivity of the dust, the less electrical
power is required to effect collection. Conditioning of
metallurgical dusts for collection is done in the iron and
steel industry by addition of water, which cools the gases
in addition to conditioning them.
4-226
-------
A. Sinter Plant Controls: Cyclone dust collectors are
normally used in sinter plants as precleaners.
Early application of wet scrubbers to sinter plants
caused erosion and imbalance of the fan blades on the
exhaust-system blowers, which provide draft through the
sinter bed to ignite the fuel. Erosion of the blades has
been a problem even with dry pollution-control systems. The
imbalance in the fan blades is aggravated by wet scrubbers
because the moist dust that is carried over to the fan tends
to accumulate on the blades, causing severe vibrations and
sometimes major breakdowns. This situation is minimized by
constant preventive maintenance to remove the dust build-
19
up.
The sinter plant (with its multitude of transfer points
for materials and discharge points for receiving, cooling,
and screening the sinter) creates a difficult fugitive emis-
sion problem. ESP's, fabric filters and scrubbers are used
for a single plant, or if the operation can be sufficiently
enclosed, a central installation may suffice. ESP's can be
used as secondary air-cleaning units in sinter-plant opera-
tions for the treatment of dust-laden gases from sintering-
] 9
strand windboxes.
Limestone additions required in the production of the
self-fluxing sinters used in modern plants increase the
4-227
-------
problems of dust-collecting systems, with the result that
19
additional ESP capacity or preconditioning is required.
Table 4-43 shows the performance of a fabric filter
application on a sinter plant windbox. The windbox exhausts
are controlled by four parallel cyclones followed by a bag-
2q
house. The cyclones are described as follows:
gas flow 68 m3/s (144,000 acfm)
temperature 177 °C (350°F)
pressure drop 2.5 kPa (10 in. w.g.)
efficiency 80-85%
pg
The fabric filter is designed as follows:
filtering velocity 2.94 cm/s (1.47 fpm)
gas flow 85 m3/s (180,000 acfm)
temperature 135°C (275°F)
pressure drop 3.5 kPa (14 in. w.g.)
cleaning reverse-air
efficiency 99%
Well-controlled facilities generally emit less than 0.11
g/m (<0.05 gr/scf) after control with fabric filters, wet
29
ESP's, venturi scrubbers, and gravel bed filters.
pi
B. Coking Oven Controls: A number of operations involved
in coking contribute to lead emissions due to the trace lead
content of coal. Unloading and charging of the coal into
the coke oven are most recently coming under control.
Automated charging cars are being equipped with wet scrubbers
to collect the coal dust and smoke generated by charging hot
ovens. However, most larry cars are not equipped with
scrubber controls in the U.S. but use controlled charging
techniques to reduce emissions.
4-228
-------
Table 4-43. SUMMARY OF PERFORMANCE TEST RESULTS
29
ON A FABRIC FILTER SERVING SINTER PLANT
Parameter
Outlet
Process feed rate, Mg/hr
tph
Flow rate, m /s
acfm
Temperature, °C
Emissions
g/m
gr/scf
g/kg
Ib/ton
133
147
97.4
207,000
160
321
0.12
0.050
0.188
0.376
4-229
-------
The coking cycle is designed to collect the volatile
matter, removed with a manifold collecting main with sprays,
followed by coal chemical removal and separation equipment.
Volatile lead compounds would most likely be evolved in this
oxygen-poor atmosphere, and very few lead mineral compounds
are broken down and emitted. The pushing operation evolves
the greatest quantity of lead by oxidation of lead minerals
in the coke. Progress is being made in the control of push-
ing emissions.
C. Blast Furnace Controls: Cyclones are normally used as
precleaners in series with scrubbers and ESP's. High-energy
scrubbers with fixed-orifice plates have been installed with
water introduced upstream from the orifice plate. These
scrubbers operated at pressure drops of 7.5 to 12.5 kPa (30
to 50 in. H,,0) , with resulting output loadings ranging from
20 to 70 mg/m3 (0.01 to 0.03 gr/ft3). The orifice scrubber,
however, had the major disadvantage that it could not handle
variations in gas flow, and consequently could not meet the
required emission limits during certain phases of blast-
furnace operation when the gases come from the blast furnace
at reduced velocity. The need for high-energy wet scrubbers
that could handle variable gas flows from a blast furnace
led to development of variable-orifice scrubbers.1^ The
first application of venturi scrubbers to blast-furnace gas
4-230
-------
was reported in 1955. Outlet dust loadings of 50 mg/m
(0.02 gr/scf) can be obtained with a water rate of 0.44 Ips
(7 gal/min) and at a pressure drop of only 5 kPa (20 in.
H20). 19
Electrostatic precipitators perform efficiently on
blast-furnaces for two reasons. First, the blast furnace
produces gas almost continuously except for comparatively
brief intervals when the blowing rate of the blast furnace
is reduced when slag is flushed or iron is cast. Second, a
high percentage of the particulate emissions are already
removed by the wet-scrubbing systems, which condition the
19
gases before they enter the ESP.
1 Q
D. Open-Hearth Furnace Controls; Wet scrubbing of open-
hearth gases used to be considered economically expedient
only for shops that were to be operated during high peak
demands for steel, when the low capital cost was considered
an advantage. Some newer open-hearth shops found, however,
that wet scrubbers were economically attractive when the
shop either had no waste heat boilers or the boilers could
not reduce the gas temperatures enough to warrant installa-
tion of ESP's or baghouses. The first open hearth installa-
tion of a wet scrubber was made in 1959, and others have
followed. Output gas loadings of 20 to 110 mg/m (0.01 to
0.05 gr/ft ) have been reported, with cleaning efficiency
4-231
-------
relating directly to the pressure drop of the scrubber. The
clean-gas dust loadings for an operating open-hearth wet
scrubber are about 0.18 to 0.03 g/m3 (0.08 to 0.015 gr/scf)
for pressure drops of 6.5 kPa to 9.2 kPa (26 to 37 in. H20)
with use of oxygen lancing during the refining period. This
performance is representative of open-hearth operation with
low oxygen-blowing rates and is not necessarily representa-
tive of present-day practice with higher oxygen-blowing
rates.
ESP's are used to control emissions from oxygen lancing
in open-hearth furnaces. The major problem with respect to
efficiency of ESP's on open hearths stems from the variable
fuel input which in turn affects the moisture content of the
gases. A dry-gas condition occurs shortly after the hot-
metal addition, lasting for about 15 to 20 minutes. It is
caused by a low fuel-firing rate, low use of atomizing
steam, and a low initial oxygen-lancing rate. The low (2
percent) moisture results in poor energy efficiency, caused
by higher resistivities requiring more power for collection
of the fume. In some cases, ESP efficiency may be improved
in two ways: (1) power input to the precipitator can be
increased, or (2) a steam-injected system can be installed
to supply the desired moisture. Increased power may be
ineffective, as with systems using limestone, which causes
4-232
-------
back ionization. Table 4-44 shows the performance of an
ESP serving an open hearth furnace,
19
E. Basic Oxygen Furnace Controls: About the same num-
bers of high-energy wet scrubbers and ESP's have been in-
stalled on basic oxygen furnaces. One of the principal
reasons for selecting ESP's over high-energy wet scrubbers
is the water-treatment problem. Problems with EOF installa-
tions are similar to .those associated with wet scrubbers in
other applications.
Improper performance of wet scrubbers can be attributed
to failure of materials to withstand the abrasive and corro-
sive action of the dust-laden water or to misapplication of
construction materials.
Table 4-45 indicates the performance of a closed hood
venturi scrubbing system installed on a basic oxygen furnace
producing 182 Mg (200 tons) of steel per heat. Other fur-
naces equipped with venturi scrubbers had outlet particulate
•J on
loadings from 0.01 to 0.1 g/m (0.004 to 0.04 gr/dscf). y
Electrostatic precipitators installed on basic oxygen
furnaces reduce particulate loadings to 0.024 to 0.080 g/m
(0.011 to 0.035 gr/dscf) which is equivalent to 0.042 to
0.14 g/kg (0.083 to 0.27 Ib/ton) of steel. 29
Problems associated with applications of ESP's to basic
oxygen furnaces are variability in flow, moisture content,
4-233
-------
Table 4-44. PERFORMANCE OF AN ELECTROSTATIC
PRECIPITATOR SERVING AN OPEN-HEARTH FURNACE
Furnace size, Mg
ton .,
Gas volume, std. m /s
scfm
Gas temperature, °C
oF
Collection efficiency, %
57.1
63
7.03
14,900
238
460
98.98
Emissions
g/m3
gi/scf
g/kg
Ib/ton
Inlet
0.817
0.355
19.8
39.6
Outlet
0.0092
0.004
0.203
0.406
The raw exhaust gas enters a waste heat boiler at 721°C
(1330°F) and is cooled to about 238°C (460°F).
4-234
-------
Table 4-45. SUMMARY OF PERFORMANCE TEST RESULTS ON A
VENTURI SCRUBBING SYSTEM SERVING A BASIC OXYGEN FURNACE
29
Parameter
Outlet
Output, Mg
tons .,
Flowrate, std. m /s
scfm
Temperature, ° C
oF
Moisture, % v
Emissions
g/m
gr/scf
g/kg steel
Ib/ton steel
1,100
1,214
18.6
39,300
64
148
12.2
0.032
0.014
0.008
0.0158
4-235
-------
and temperature of the entering gases. A significant design
problem for new basic oxygen furnaces is the possibility of
increases in production rate as technology advances. EOF
technology is developing so rapidly that significant in-
creases in production do occur, sometimes as high as 22
percent. One reason for increased productivity is increased
oxygen-blowing rates, resulting in at least a proportionate
increase in iron-oxide fume. Such larger-volume increases
can render the ESP system inadequate.
Maintenance problems with ESP's are associated with
wire rappers, vibrators, and insulators. The hoods over the
EOF can result in operating problems. The gap between the
EOF and the hood is usually dictated by the anticipated
operating conditions and the anticipated buildup of a skull
on the mouth of the furnace. Excess buildup can restrict
the flow of air required for combustion of the carbon monoxide,
resulting in a potentially dangerous amount of carbon
monoxide reaching the ESP and causing an explosion hazard.
19
Electric Furnace Controls: Fabric filter and high
energy venturi scrubbers have been applied successfully to
control of emissions from both single and multiple electric
furnaces ranging up to 91 and 136 net-Mg capacity (100 and
150 net-tons). Because the furnace design and operating
characteristics are variables, however, development of
pollution controls is not as straight forward as for other
4-236
-------
steelmaking operations. One of the major design problems
entails the fume collection system. Most electric-arc furnaces
are top-charged, involving removal of the roof during charging
Capture of fumes by hoods and by direct extraction during
melting and refining has not completely solved the problems
of collection and containment. Techniques for control of
fumes from the plant roof have been achieved to control
emissions from the entire plant.
Table 4-46 indicates typical performances of a fabric
filter on electric arc furnaces producing steel. In this
particular test, two 22 Mg (25 ton) furnaces producing alloy
and stainless steels were controlled by a baghouse.
Emissions from well-controlled electric arc furnaces
range from 3.9 to 18 Mg/m3 (0.0017 to 0.008 gr/dscf) or
0.015 to 0.067 kg/h per Mg (0.034 to 0.148 Ib/hr per ton) of
furnace capacity.
4-237
-------
Table 4-46. PERFORMANCE OF FABRIC FILTER SERVING AN
29
ELECTRIC-ARC FURNACE
Parameter
Furnace size, Mg
tons,.
Gas volume, std. m /s
dscfm
Temperature, °C
oj-
Moisture, % V
Emissions
g/m
gr/scf
kg/h'Mg capacity
lb/hr-ton capacity
Inlet
45
50
99
209,000
38
100
1.02
0.059
0.0257
0.462
0.923
Outlet
45
50
7.6
16,160
33
91
1.3
0.0039
0.0017
0.031
0.062
4-238
-------
4.5.2.5 Control Costs - Particulate control costs given in
this section, except for coke ovens, are derived from a
29
detailed cost analysis in the literature. This extensive
study is assumed to provide more accurate cost data than for
the procedure given in Appendix B. Equipment costs include
foundations, ductwork, stack, collector, fan system, structures,
electrical, water treatment and piping, controls, and cooling
equipment. These costs do not include product recovery
cyclones and equipment upstream of product recovery units,
including ductwork, canopy hoods, cooling equipment, etc.
Capital costs include material and labor for field erection,
freight, taxes, insurance, engineering, start-up, inventory,
land, and interest during construction. Annualized costs
include utilities, maintenance, labor, overhead, and fixed
costs (with capital recovery).
A. Sintering Plant Windbox - A 907 Mg/day (1000 TPD)
sinter plant windbox discharges 50 m /s at 163°C (105,000
acfm at 325°F), after cooling and product recovery, to a
venturi scrubber. Particulate emissions are about 160 kg/h
(350 Ib/hr) assuming 80 percent efficient cyclones. The
average state emission limitation is 23 kg/h (50 Ib/hr),
assuming 2.3 kg input per kg output (2.3 Ib input/lb out-
put) .
Total capital costs for the above control system are
estimated at $945,000. Total annualized costs are estimated
4-239
-------
at $441,000. Product recovery credit is not included in the
costs. Annual operating time is approximately 8000 hours
29
and the annual labor requirement is about 6000 hours.
A 5440 Mg/day (6000 TPD) sinter plant windbox discharges
285 m3/s at 163°C (603,000 acfm at 325°F), after cooling and
product recovery, to a venturi scrubber. Particulate emissions
are about 960 kg/h (2100 Ib/hr) assuming 80 percent efficient
cyclones. The average state emission limitation is 32 kg/h
(70 Ib/hr).
Total capital costs for the above system are estimated
at $4.01 million. Total annualized costs are estimated at
$1.79 million, not including dust recovery credit. An annual
operating time of 8000 hours and operating labor of 2 men/day
are assumed.
The capital and annualized costs are expressed in terms
of collector inlet gas volume and annual labor hours below.
These equations are developed from the two model plant
examples given above.
S.I, units
Capital, $ = 3.68 x 104V°'83
Annualized, $ = 1570V + 19.6H + 104V°'83
V = m3/s at 163°C
H = annual labor hours
100 < V < 950
range
4-240
-------
English units
n R "3
Capital, $ = 63.9 QU'°J
Annualized, $ = 0.72Q + 19.6 H + 17.4Q0'83
Q = acfm at 325°F
H = annual labor hours
200,000 < Q < 1,800,000
range
B. Sinter Plant Material Handling - A 907 Mg/day (1000
TPD) sinter plant material handling operation is controlled
by a fabric filter at a rated capacity of 23 m /s at 57°C
(48,000 acfm at 135°F). Capital costs are estimated at
$617,000, and annualized costs are estimated at $245,000,
not including dust recovery credit. An annual operating
time of 8000 hours and operating labor of 3000 hours are
assumed.
A 5440 Mg/day (6000 TPD) sinter plant material handling
operation is controlled by a fabric filter system rated at
118 m3/s at 57°C (250,000 acfm at 135°F). Capital costs are
estimated at $1.63 million and annualized costs are esti-
mated at $685,000, not including dust recovery credit. An
annual operating time of 8000 hours and operating labor of
7300 hours are assumed.
The capital and annualized costs are expressed in col-
lector inlet volume and annual labor hours below:
4-241
-------
S.I, units
Capital, $ = 97,600 V0'59
Annualized, $ = 1100V + 25,500V°'59 + 19.6H
V = mS/s at 57°C
H = annual labor hours
20 < V < 120
range
English units
Capital, $ = 1065 Q°'59
Annualized, $ = 0.52Q + 278Q0'59 + 19.6H
Q = acfm at 135°F
H = annual labor hours
40,000 < Q < 250,000
range
C. Electric Arc Furnace - Two 22.7 Mg/heat (25 ton/
heat) electric arc furnaces discharge 28.3 ra /s at 135°C
(60,000 acfm at 275°F), after cooling, to a fabric filter
system. Capital costs are estimated at $578,000 and annu-
alized costs are estimated at $248,000, not including dust
recovery credit. An annual operating time of 8000 hours and
operating labor of 4000 hours are assumed.
Two 227 Mg/heat (250 ton/heat) electric arc furnaces
discharge 165 m /s at 135°C (350,000 acfm at 275°F), after
cooling, to a fabric filter system. Capital costs are esti-
mated at $3.01 million; annualized costs are estimated at
$1.11 million. Operating time and labor requirements are each
4-242
-------
8000 hours per year.
The furnace exhausts are cooled from 815°C to 315°C
(1500°F to 600°F) by a radiant heat exchanger and from 315°C
to 135°C (600°F to 275°F) by air dilution prior to entering
the fabric filter. Uncontrolled particulate emissions are
5.5 g/kg (11 Ib/ton) of which 2 percent is lead. This
control technique provides 99 percent or more reduction,
sufficient to meet state regulations.
The capital and annualized costs are expressed in terms
of collector inlet volume and annual labor hours below:
S.I, units
Capital, $ = 26,000 V°*93
Annualized, $ = 1060V + 6790V°'93 + 19.6H
V = m3/s at 135°C
H = annual labor hours
28 < V < 165
range
English units
0 93
Capital, $ = 21 Q
Annualized, $ = 0.5Q + 5.48Q°>93 + 19.6H
Q = acfm at 275°F
H = annual labor hours
60,000 < Q < 350,000
4-243
-------
D. Open Hearth - A 54 Mg/heat (60 ton/heat) open
hearth furnace discharges 13.7 m3/s at 260°C (29,000 acfm at
500°F) after product recovery cyclones and cooling, to an
electrostatic precipitator. Capital costs are estimated at
$655,000 and annualized costs are estimated at $240,000. An
annual operating time of 8000 hours and annual labor of 4000
hours are assumed.
A 544 Mg/heat (600 ton/heat) open hearth furnace dis-
charges 106 m3/s at 260°C (225,000 acfm at 500°F), after
product recovery and cooling, to an electrostatic precipita-
tor. Capital costs are estimated at $3.28 million and
annualized costs are estimated at $1.08 million. An annual
operating time of 8000 hours and annual labor of 8000 hours
are assumed.
Gases are cooled to 260°C (500°F) by waste heat boilers.
Boilers and boiler fans are not included in the capital
costs. Open hearth emissions are about 8.7 g/kg steel (17
Ib/ton), averaging 0.8 percent lead. The systems are designed
to meet state standards.
Capital and annualized costs are expressed in terms of
collector inlet volume and annual labor hours below:
S.I, units
Capital, $ = 83,300 v°'787
Annualized, $ = 1820V + 18,900V0'787 + 19.6H
4-244
-------
V = m3/s at 260°F
H = annual labor hours
10 < V < 120
range
English units
Capital, $ = 201 Q°'787
D 7R7
Annualized, $ = 0.86Q + 45.6Q + 19.6H
Q = acfm at 500°F
H = annual labor hours
20,000 < Q < 300,000
range
E. Blast Furnace - A 210 Mg/hr (230 tph) capacity
blast furnace will exhaust 100 std. m /s (210,000 scfm) to a
two-stage high-energy scrubber. Particulate emissions are
3100 kg/h (6900 Ib/hr) assuming 80 percent product recovery.
Lead content may be near 800 ppm. The average state standard
of 27 kg/hr (60 Ib/hr) can be achieved by 99 percent reduction.
Capital costs are estimated at $6.2 million. Annualized
costs are estimated at $1.91 million. I.D. fans are not
required. Annual operating and labor time are each assumed to be
8000 hours.
39
F. Coking - Although there is no one ideal solution
to coke oven emissions, there are several alternative de-
velopments for controlling coke oven charging emissions.
The most significant of these alternatives are: pipeline
charging, the AISI system, wet scrubber charging, jumper
4-245
-------
pipe charging, dual collecting main system, and full en-
closure of the battery. It appears that the jumper pipe
charging method is,with a new larry car,- the most economical
alternative for retrofitting existing coke oven batteries.
The installed equipment costs for a single battery are
as follows:
0 Mechanical feed larry car with jumper pipe, lid
lifters, interlock, environmental unit, gooseneck
cleaner $880,000
0 Leveler bar smoke seal $ 68,000
0 Steam piping and nozzles $ 68,000
0 Realign charging hole castings $ 81,000
0 New charging hole and standpipe lids with damper
operation $108,000
For four batteries of sixty fifteen-ton ovens, capital
costs are estimated at $3.64 million. Annualized costs are
estimated at $400,000, including operation, maintenance,
repair, taxes, insurance, and labor credits.
4-246
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G. Basic Oxygen Furnace - A 91 Mg/h (100 TPH) basic oxygen
3
furnace exhausts 104 m /s of gas at 82°C (220,000 acfm at
180°F) to a high energy venturi scrubber, after cooling and
conditioning with cyclone separators and a spray chamber.
The uncontrolled particulate emission rate is 2.3 Mg/h
(5,100 Ib/hr), of which 0.4 percent by weight is lead. With
70 to 80 percent efficient cyclones, a 98 percent efficient
venturi scrubbing system will meet a typical state emission
standard of about 13.6 kg/h (30 Ib/hr) particulate.
The capital costs are estimated at $4.22 million. This
includes the collector, fan system, duct work, spray chamber,
and wastewater treatment.
The annualized costs are estimated at $2.05 million,
including utilities, maintenance, labor, overhead, and fixed
costs (with capital recovery). Labor and operating time is
8000 hours per year. Solids collected are recycled to the
furnace.
A 272 Mg/hour (300 ton/hour) basic oxygen furnace
exhausts 312 m3/s of gas at 82°C (660,000 acfm at 180°F) to
a high energy venturi scrubber after being cooled from 650°C
(1200°F) by water sprays. The particulate emission rate is
about 8.55 Mg/h (15,300 Ib/hr) before treating in product
recovery cyclones. The lead content of the particulate
matter is about 0.4 percent by weight. With 80 percent
4-247
-------
efficient cyclones, a 98 percent efficient scrubber will
meet a typical state emission regulation of about 27.2 kg/h
(60 Ib/hr).
The capital costs for the venturi scrubbing system are
estimated at $8.91 million. This includes cooling equip-
ment, ductwork, fan system and wastewater treatment.
The annualized costs are estimated at $5.15 million,
including utilities, maintenance, labor, overhead and fixed
costs (with capital recovery). Annual operating time is
assumed at 8000 hours. Labor requirements are about 16,000
hours/year. Solids collected are recycled to the furnace.
The capital and annualized cost equations are developed
from the two model plants and are given below in terms of
inlet flow rate and annual labor hours;
S.I, units
Capital, $ = 18,000 v°'68
0 r p
Annualized, $ = 48,800 V 'D0 + 19.6 H + 7620 V
V = m3/s at 82°C
H = annual labor hours
100 < V < 300
range
Capital, $ = 983 Q°'68
English units
Annualized, $ = 267 Q°'68 + 19.6 H + 3.6
Q = acfm at 180°F
H = annual labor hours
220,000 < Q < 660,000
Q
4-248
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4.5.2.6 Impacts
A. Sintering
Particulate emission reductions for sintering controls
are estimated at 21 g/kg sinter (42 Ib/ton) at a lead con-
tent of 320 ppm. For a 7 kPa (30 in. WG) venturi for the
large model sinter plant, energy requirements are 0.024
GJ/Mg of sinter (0.024 MM Btu/ton) and 0.011 GJ/Mg of sinter
(0.011 MM Btu/ton) for the material handling fabric filter,
compared to a total of 32 GJ/Mg (32 MM Btu/ton) to produce
finished steel. Solid wastes generated by the iron and
steel industry averages about 1.3 Mg/Mg product (1.3 ton/ton)
including mining, milling, and processing, compared to
about 8 kg/Mg iron and steel (16 Ib/ton) generated by air
pollution control on sintering. Raw wastewater discharged
by sintering operations amounts to about 0.1 to 0.4 m /Mg of
30
sinter (400 to 1500 gal/ton), a relatively small amount.
3
Based on data contained in Table 4-38, about 24 m /Gg of
sinter (100 gal/ton) could be generated by a wet collector.
However, the total wastewater generated by the steel plants
is estimated at 5 to 10 m3/Mg steel (20,000 to 40,000
33
gal/ton steel) from the raw ore to the finished steel.
B. Blast Furnace
Particulate emission reduction with blast furnace
emission control is estimated at 75 kg/Mg iron (150 Ib/ton)
4-249
-------
containing about 800 ppm of lead. Total energy demand for a
blast furnace is 13 GJ/Mg (13 MM Btu/ton) of steel produced.
The energy requirements for the high-energy scrubber on the
model plant, assuming 7.5 kPa (30 in. WG) pressure drop, is
about 0.013 GJ/Mg (0.013 MM Btu/ton) of steel, about 0.1
percent of the total plant consumption. Total plant raw
wastewater amounts to 5 to 10 m /Mg of steel (20,000 to
40,000 gal/ton), compared to that produced by the furnace
itself which is 0.5 to 1.3 m3/Mg (2000 to 5600 gal/ton).32
Water requirements for the scrubber could be about 1.3m /Mg
of steel (300 gal/ton) or a maximum increase of 2 percent.
Solid waste (slag) from the blast furnace amounts to 200
kg/Mg of iron (400 Ib/ton) which is recycled to the
sintering operation. Air pollution control may generate an
additional 75 kg/Mg (150 Ib/ton) which is also recycled to
the sinter plant.
C. Open Hearth Furnace
Particulate emission reduction by air pollution control
is estimated at 8.7 kg/Mg steel (17.4 Ib/ton) for the open-
hearth furnace. Lead content is about 0.8 percent by
weight. Energy demand for the process is about 3.2 GJ/Mg
steel (3.2 MM Btu/ton) compared to about 3.4 GJ/Mg (3400
Btu/ton) for the ESP systems on the model plant, assuming a
0.5 kPa (2 in. WG) pressure drop. The wastewater produced
4-250
-------
3 432
amounts to 2.5 m /Mg steel (10 gal/ton). Although wet
collectors are no longer feasible control for open hearths,
24 m /Gg (100 gal/ton) would be generated by this type of
emission control. Solid wastes from open-hearths are not
quantified here, but 1.3 Mg/Mg steel (1.3 ton/ton) is the
industry's average to produce steel, compared with only
8.7 kg/Mg (17.4 Ib/ton) contributed by emission control.
Solid wastes are generally recycled.
D. Basic Oxygen Furnace
Particulate emission reduction from EOF controls will
be about 25 kg/Mg of steel (50 Ib/ton) with a lead content
of about 0.4 percent. The energy required for the process
is about 0.35 GJ/Mg steel (0.35 MM Btu/ton). The high-
energy scrubber, operating at 8 kPa (32 in. WG) pressure
drop, requires about 0.05 GJ/Mg steel (0.05 MM Btu/ton) for
the large model BOF, compared to a total of 32 GJ/Mg (32 MM
Btu/ton) to produce steel. About 0.54 to 4.3 m /Mg steel
(2200 to 18,000 gal/ton) of raw wastewater is generated by
32 3
the BOF. The scrubbing system may produce about 23 m /kg
(110 gal/ton). Solid wastes from the BOF, including emis-
sion control, is generally recycled. The solid wastes
collected by emission control devices amount to 25 kg/Mg
steel (50 Ib/ton) compared to about 1.3 Mg/Mg steel (1.3
31
ton/ton) for the entire steelmaking process.
4-251
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E. Electric Arc Furnace
Particulate emission reductions by control systems on
electric arc furnaces amount to about 5 kg/Mg steel (10
Ib/ton) with a lead content ranging from 0 to 5.7 percent,
with an average of 2.0 percent. Energy requirements for the
electric arc process are about 2.0 GJ/Mg steel (2.0 MM Btu/
ton) and 32 GJ/Mg (32 MM Btu/ton) for the entire steelmaking
process. The fabric filter on the large model process
consumes about 14 GJ/kg of steel (0.014 MM Btu/ton) with a
pressure drop of 1.2 kPa (5 in. WG). A venturi scrubber
will consume 84 GJ/kg (0.084 MM Btu/ton) with a pressure
drop of 7.5 kPa (30 in. WG). Electric arc furnaces generate
0.4 to 1.3 m3/Mg steel (100 to 310 gal/ton) of raw waste-
water compared to a total of 80 to 160 m /Mg (20,000 to
40,000 gal/ton) for the entire steelmaking operation. For
the model electric arc furnace about 0.8 m /Mg steel (200
gal/ton) of wastewater will be generated. Solid waste pro-
duced by electric arc furnaces amount to about 5 kg/Mg steel
(10 Ib/ton) which is generally recycled.
F. Coking
Particulate emission reduction by coking controls are
estimated at 1.8 kg/Mg (3.5 Ib/ton) of coal charged.
Pushing emissions may be about 0.01 percent lead. No
4-252
-------
volumetric data or energy consumption data on coking control
systems are available, however total coking energy con-
sumption has been estimated at 2.85 GJ/Mg of steel produced
(2.85 MM Btu/ton). No water consumption can be calcu-
lated, however the total raw wastewater amounts to 0.16 to
3 32
17 m /Mg (40-4200 gal/ton) of steel. No solid waste data
are available for the coking operations, however only 1.8
kg/Mg coal charged (3.5 Ib/ton) of solid wastes would be
generated by emission control.
4-253
-------
4.5.3 Ferroalloy Production
The main use of ferroalloys in the United States is in
the deoxidation, alloying, and graphitization of steel.
Ferroalloys consist of iron in combination with one or more
other elements, including silicon, chromium, manganese, and
many other elements in minor quantities.
The United States is the world's leading producer of
ferroalloys, producing 1.83 Tg (2.02 x 10 tons) in 1975 at
47 plants. More than half of the total production occurred
in Ohio and Pennsylvania. Table 4-47 shows the 1975
production of the various types of ferroalloys.
Table 4-47. U.S. FERROALLOY PRODUCTION IN 1975a
Ferro-manganese (FeMn)
Silico-manganese (SiMn)
Ferro- silicon
(Fe2sif incl. silvery
pig iron)
Ferro-chromiums (FeCr)
Other ferroalloys (FeP,
FeCo, FeTi, etc.)
Total estimated production
Tg
0.551
0.202
0.726
0.222
0.127
1.828
Tons
607,697
222,772
800,000
244,938
140,000
2,015,000
Obtained from Mr. Thomas Jones, U.S. Bureau of Mines,
Ferroalloys Division, Washington, D.C. July 20, 1976
Gross production figures.
4-254
-------
The 1975 lead emissions from U.S. ferroalloy production
are estimated at 30 Mg (33 tons), not including fugitive
emissions.
4.5.3.1 Process Description - Figure 4-46 illustrates a
typical flow diagram for a ferroalloy facility.
A. Ore Handling: The ore and other raw materials are
usually transported to the plant by rail and are stored.
The materials are mixed, blended, and sized prior to being
weighed and charged into furnaces. Fugitive dusts from
these operations are approximately 5 g/kg of alloy produced
(10 Ib/ton) ,35
B. Smelting; Furnace operation in the smelting of ferro-
alloys constitutes the major pollution problem and the
largest source of lead emissions. Lead is a naturally
occurring trace element of variable concentrations in the
raw materials.36 Smelting is done in three types of furnaces
electric, aluminothermic, and blast furnaces, of which over
90 percent are electric submerged-arc furnaces, as shown in
Figure 4-47.37
The basic design and operation of all ferroalloy-
producing electric furnaces are essentially the same. The
typical furnace is of the submerged-arc type. The charge
consists of raw ore with a reducing agent, such as alumina,
coal and/or coke, and slagging materials such as silica or
gravel. The zone of intense heat (2200 to 2800°C, or 4000
4-255
-------
SMELTING
Ul
CTl
1
1- LIMESTONE
h IRON SCRAP 0
fSLAG CONCENTRATE!
- J^- BLAST FURNACE
f
j-FUEL I
COKE <)
r LIMESTONE
-SCRAP
-COKE
- SLAG Q
- CONCENTRATE Y
A
v^
rSLAG
h CONCENTRATE ?
ALUHIHO
*" THERMAL
f FURNACE
^ALUMINUM SCRAP 1
^
'SLAG
1
SLAG
SLAS
1
,
FINISHING OPERATIONS
? ? ?!
» CASTING »^ -I'E REDUCTION ». P«KING AND !
» CASTING >- JUE REDUCTION ». SKIPPING ,
1
I
|_ J
_ SLAG
CONCENTRATIVE »• RECOVERED CONCENTRATE TO FURNACE
UNIT
6
RESIDUE TO
HASTE DISPOSAL
Figure 4-46. Ferroalloy production flow diagram.
-------
ELECTRODES
REACTION
GASES
TO BAGHOUSE
HOOD
CHARGE
MATERIAL
REFRACTORY LINING
SHELL
CRUCIBLE
TAP HOLE
MOLTEN FERROALLOY
LADLE
Figure 4-47. Submerged-arc furnace for ferroalloy production
4-257
-------
to 5000°F) around the carbon electrodes is responsible for
carbon reduction of the metallic oxides present. The
various impurities are trapped in the slag, and the molten
ferroalloy is tapped from the bottom of the furnace and
. 37
cast.
The aluminothermic process, involving the co-reduction
of iron oxides and other metallic oxides by aluminum, is
uncommon in the United States. Charge to the furnace
consists of raw ore, aluminum powder, iron scrap or mill
scale, a thermal booster such as sodium chlorate, and a
fluxing agent, usually lime or fluorspar. The reaction may
be initiated by two methods. One involves ignition of the
mix with an electrical arc from submerged electrodes. The
other involves use of a small quantity of a mixture of
aluminum with barium peroxide to ignite a priming batch, to
which the charge is slowly added. After initial ignition
occurs, the reaction is highly exothermic and the smelt is
accomplished with no further addition of energy. The tem-
perature of the reaction is controlled by adjusting the size
of the charge particles and the feed rate of the charge, or
by replacing some of the aluminum with a milder reductant,
such as calcium carbide, silicon, or carbon. The ferroalloy
is tapped from the bottom of the furnace and cast. Typical
ferroalloys produced by this method include ferroboron,
4-258
-------
ferrochromium, ferroniobium, ferromolybdenum, ferrotItanium,
•3 c
ferrotungsten, and ferrovanadium.
Blast furnaces, like aluminothermic furnaces, are of
minor importance in production of ferroalloys; only two are
now in operation in the United States. The charge consists
of raw ore, iron ore, coke, and limestone. The furnace is
fired with fuel oil or natural gas, and usually operated at
around 1430°C (2606°F), just above the slag formation
temperature of 1426°C (2699°F). The ores undergo carbon
reduction and the ferroalloy sinks to the bottom of the
furnace, where it is tapped and cast. Temperature of the
exit gases is usually between 370 and 480°C (700 and 900°F),35
C. Slag Processing: The slag is treated by two methods:
concentration and shotting. In the concentration process,
the slag is dumped in water, where metal particles sink to
the bottom and are recovered while the slag floats and is
removed. The recovered metals and other wastes from the
shipping department are recycled to the furnace charge; as
high as 30 percent of the charge may be recycled material.
The concentration process is generally used on ferrochromium
slags. The shotting method, which involves the granulation
of molten slag in water, may be used on ferromanganese
slags. There are no significant atmospheric emissions.
D. Finishing Operations;35 Hot metal from the furnace is
usually cast in ingot form in various types of molds depend-
4-259
-------
ing on the ferroalloy produced. Several kinds of mold
coatings and toppings are used. After sufficient cooling
and solidification, the casts are removed from the molds,
graded, and placed in hot metal skip boxes, where the alloy
is held for further processing. The casts are processed by
hand breaking or by use of pneumatic breakers, depending on
the ease with which they can be broken. At some plants the
ferroalloy casts are washed free of disintegrated slag
(prior to breaking) to insure cleanliness.
The broken material from the casts is passed through a
crusher and screen to produce materials of uniform size.
Cranes are used for feeding the crushers. If two crushers
are used, material from the primary crusher is transferred
to the secondary crusher by belt conveyors. The crushing
and screening operations result in particulate emissions
that may be easily controlled.
4.5.3.2 Emissions
A. Electric Arc Furnaces: Power requirements for the
electric furnace range from 9.6 to 56 TJ/kg of product (2.4-
14 MWh/ton) depending on the grade of ore and the type and
size of furnace.38 The quantity of gas generated (before
dilution) is approximately proportional to the electrical
energy input. 6 Exhaust rates for the production of common
alloys are presented in Table 4-48.
4-260
-------
Table 4-48. CHARACTERISTICS OF EXHAUST GAS FROM OPEN ELECTRIC FURNACES
PROCESSING COMMON FERROALLOYS
Product
Silicon metal
50% Ferrosilicon
75% Ferrosilicon
90% Ferrosilicon
Standard ferromanganese
Silicomanganese
Ferrochrome- silicon
H.C. ferrochrome
Volume,36
m'/s-Mwa
8.0
4.3
8.8
N.'-A.
2.8-6.1
2.4-5.7
1.6
2.3
scfm/MWa
17,000
79,200
18,600
N.A.
6, 000-13, 00(
5, 000-12, 00(
3,400
4,800
Emissions ,
g/kg product (Ib/ton)
particulate^o
600
225
335
335
168
110
415
170
1200
450
670
670
335
220
830
340
lead
0.0015 (0.0031)
0.15 (0.29)
N.A.
N.A.
0.06 (0.11)
0.29 (0.57)
0.04 (0.08)
0.17 (0.34)
1
fo
Based on gas saturated at 38°C (100°F), and volume at 4 kPa (30 in. Hg) and
16°C (60°F).
-------
Emissions from electric furnaces vary widely, depending
mainly on the ferroalloy being produced, type and operation
of furnace, and charge composition. Large quantities of
gases are released during electric furnace operation. The
gases are produced as a result of carbon reduction, moisture
in the raw material, thermal decomposition of the raw ore,
vaporization of volatile components, and intermediate
reactions releasing gases as products. Approximately 70
percent by volume of the gases released is carbon monoxide.
Other minor gaseous components are volatilized metallic
oxides, sulfur oxides, cyanides, and phenols. In an open
electric furnace, the released gases are burned and virtu-
ally all the carbon monoxide, cyanides, and phenols are
destroyed. In a covered electric furnace, however, large
quantities of phenols and cyanides are emitted unless the
gases are either incinerated or used as fuel.
Particulate and lead emission factors are given in
Table 4-48 for electric furnaces producing common ferro-
alloys. X-ray diffraction analysis of dust fumes from
furnaces processing silicon-manganese and manganese ore-lime
indicated j.ead oxide contents of 4700 and 9800 ppm, respec-
tively- One EPA source test for SiMn production indicated
an average lead content of 520 ppm.40 Based on a particulate
emission factor of 110 g/kg product (220 lb/ton),2 and an
average of 2610 ppm lead, a lead emission factor of 0.29
g/kq (0.57 lb/ton) was determined for SiMn production
4-262
-------
in electric furnaces. Because there is no particulate
emission factor for manganese-lime production, no lead
emission factor can be developed.
An EPA test on a furnace producing silicon metal showed
a lead content of only 2.6 ppm in the uncontrolled particu-
41
late emission, which yields a lead emission factor of 1.5
mg/kg Si metal (0.0031 Ib/ton) produced in an electric
furnace.
The average lead content of particulates from ferro-
manganese electric and blast furnaces is reported to be 200
42 43
ppm. ' One EPA source test indicated a lead content of
40
430 ppm. Combined with an EPA particulate emission factor
of 168 g/kg FeMn (335 Ib/ton), a lead emission factor of 0.0375
g/kg (0.075 Ib/ton) was developed for the electric furnace,
based on an average lead content of 315 ppm.
EPA tests on 50 percent FeSi production indicated a lead
content of particulate emissions to be 650 ppm; for high car-
bon FeCr production, 1000 ppm; and for SiFeCr production,
1000 ppm. Emission factors for particulate and lead are
shown in Table 4-48. Measured at the furnace outlet, exhaust
gas temperatures are 590 to 700°C (1100-1300°F) for a closed
furnace and 200 to 260°C (400-500°F) for an open furnace,
grain loadings are 11.4 to 68.7 g/m and 0.23 to 0.46 g/m
(5-30 gr/scf and 0.1-0.2 gr/scf), respectively-
4-263
-------
B. Aluminothermic Furnaces; As with electric furnaces,
emissions from aluminothermic furnaces vary widely in type
and quantity, depending upon the ferroalloy and the physical
characteristics of the charge. Large amounts of gases are
released, consisting of volatile metallics, water vapor,
carbon monoxide, and other gases absorbed in the charge
materials. Particulate emissions are substantial because of
the fineness of the charged materials and the violence of
the reaction. Emissions are similar to those of the elec-
tric furnace. The composition of the particulates emitted
varies widely with different ore compositions; emissions
consist primarily of oxides of the different charging
materials.
C. Blast Furnace: Since the basis of operation of the
blast furnace is carbon reduction, the major constituent of
the gases emitted is carbon monoxide. Other gaseous com-
ponents are volatilized metallics, sulfur oxides, and various
organics. Most of the combustible gases, especially CO, are
burned before being emitted to the atmosphere or are used as
fuel for other processes.
The escaping gases may carry large quantities of dense
smoke, created by the disintegration of coke and ore and by
vaporization and condensation of various materials. Parti-
culate emissions are 205 g/kg of product (410 lb/ton).2
Approximately 20 percent of the particulates emitted consist
4-264
-------
of particles larger than 20 ym. The remaining 80 percent
consist of particles in the range of 0.1 to 1.0 ym. Pro-
duction of ferrmanganese in blast furnaces can generate
particulate emissions containing 0.02 percent lead. With
2
an EPA particulate emission factor of 205 g/kg (410 Ib/ton),
the lead emission factor is 0.041 g/kg product (0.082 Ib/ton)
D. Nationwide Emissions: The 1975 nationwide lead emis-
sions from ferroalloy production cannot be accurately deter-
mined because of lack of data. Production of ferroalloys
caused the emission of an estimated Mg of lead (33 tons), as
shown in Table 4-49.
4.5.3.3 Control Techniques - Air pollution controls on
ferroalloy furnaces consist of wet scrubbers and fabric
filters. Application of electrostatic precipitators is
somewhat limited.
A. Exhaust Capture; Various hooding arrangements are
possible, depending on whether the furnace is open, semi-
covered, or closed. The open furnace is covered with a
hood, as shown in Figure 4-47, at least the diameter of the
furnace shell and with an opening inlet velocity of 0.91 m/s
14
(3 fps) minimum. Ventilation air must be sufficient to
completely combust carbon monoxide in the off-gas. Open
furnaces, by far the most popular, generate 50 to 100 times
38
the volume of closed furnaces. Fugitive emissions escap-
ing from open hoods are a major problem.
4-265
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Table 4-49. LEAD EMISSIONS FROM FERROALLOY PRODUCTION
i
to
CTi
Product
FeMn
FeSi
SiMn
H-C.FeCr
SiFeCr
Other
Production3
T*
0.551
0.730
0.202
0.152
0.070
0.127
10° tons
0.608
0.800
0.223
0.168
0.077
0.140
Lead emission factor
g/kg
0.055
0.15d
0.29
0.17
0.04
0.14e
Ib/ton
0.11
0.29d
0.57
0.34
0.08
0.28S
Total lead emissions
£»
Lead emissions
Mg
3.3
15.2
6.3
2.8
0.3
2.0
30
tons
3.6
16.8
7.0
3.1
0.3
2.2
33
Obtained from Mr. Thomas Jones. U.S. Bureau of Mines. Ferroalloys
Division. Washington, D.C. July 20, 1976.
Assuming all production is from electric arc furnaces.(see Table 4-48)
c Assuming 89 percent collection efficiency.
Based on weighted-average particulate factor of 293 g/kg (586 Ib/ton).
e Average of all emission factors.
-------
B. Wet Scrubbers: High-energy venturi scrubbers, flooded-
disc type, are common control devices for open and semi-
covered electric arc furnace. Reported efficiencies are 96
percent (0.11 g/m or 0.05 gr/scf) to 99 percent (0.05 g/m3
or 0.02 gr/scf) or higher, with pressure drops of 15 to 20
44
kPa (60 to 80 in. H2O). High pressure drops are required
because of fine particle size and high electrostatic charge.
Water rates are on the order of 0.54 to 1.07 1/m (5-10
gpm/10 acfm). Power requirements are approximately 10
percent of the megawatt capacity of an open furnace-*8 and
considerably less for a closed furnace.
Centrifugal multistage wet scrubbers can also achieve
efficiencies of 99 percent. Centrifugal devices are installed
only on semicovered or closed furnaces, where exhaust volumes
are much lower. Apparently blast furnace controls may
attain similar efficiencies with lower pressure drop. One
venturi installation on a blast furnace in England achieved
46 mg/m (0.02 gr/scf) with a pressure drop of 6.0 kPa (24
in. H20) and a water rate of 0.67 1/m3 (5 gal/103 ft3).38
Lime treatment of scrubbing water is required for furnaces
44
processing high-sulfur ores.
C. Fabric Filters; Use of fabric filters on ferroalloy
furnaces is also quite common. Mechanical precleaning is
desirable to prevent spark carryover. Radiant or dilution
4-267
-------
cooling is required to reduce temperatures from 649°C
(1200°F) to 121 to 149°C (250-300°F). Adiabatic cooling (by
44
water sprays) is not recommended.
Reverse-air or mechanical shaking may be designed for
filtering velocities of 0.6 to 1.0 cm/s (1.2-2.0 fpm) .
Pulse-jet cleaning may be utilized at a higher filtering
velocity of 4.5 cm/s (9 fpm). Pressure drops of 2.5 to 4.5
kPa (10-18 in. H2O) can be expected because of the very fine
particle size and electrostatic characteristics of the dust.
Cloth material may be woven or felted; specific materials
38
are determined by system design.
An open 36 MW nominal capacity electric submerged arc
furnace producing 75 percent ferrosilicon was tested. The
data are shown in Tabla 4-50. The are pollution control system
consists of a hood, settling chamber, and closed pressure
bag filter with three stacks. Tested by EPA using Method 5
except that the probe and filter were not heated. Sampling
was performed on one stack only, and air flows were measured
on the other two stacks. Total emissions were calculated as
the product of particulate concentrations as determined on
one stack and total air flow to the baghouse. The results
indicate the typical performance expected by fabric filters
on electric arc furnaces. Properly designed fabric filters,
ESP's, and venturi scrubbers can consistently achieve parti-
culate emissions of 0.5 to 0.9 kg/MWh (1.0 to 2.0 Ib/MWhr).38
4-268
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Table 4-50. TEST RESULTS ON AN ELECTRIC ARC FURNACE
O O
EQUIPPED WITH FABRIC FILTER
Test time-minutes
Average power input-
megawatts
Stack effluent
Flow rate m /s (dscfm)
Temperature, °C (°F)
Water vapor - vol. %
C02 - vol. % dry
02 - vol. % dry
CO - vol. % dry
N2 and other gases -
vol. % dry
130
22.3
74.5 (158,000)
193 (379)
1.9
1.7
19.8
0.0
78.5
Visible emissions at control
system discharge - % opacity £15
Particulate emissions
g/m3 (std) (gr/dscf)
g/m (gr/acf)
kg/hr (Ib/hr)
kg/GJ (Ib/Mw-hr)
0.017 (0.02691)
0.007 (0.01682)
16.4 (35.98)
2.63 (1.61)
D. Electrostatic Precipitators: ESP's are installed to a
limited extent on open electric arc furnaces producing
silicon, ferrosilicon, ferrochrome-silicon, and silicoman-
ganese. At gas temperatures below 260°C (500°F) the resis-
tivity of ferroalloy dusts exceed the 10 ohm-cm resistiv-
ity limit for practical electrical precipitation. Gas
conditioning with water, steam, or ammonia would lower
resistivity.
44
4-269
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4.5.3.4 Control Costs - A 30 MW electric submerged-arc
ferroalloy furnace producing 6.35 Mg/h (7.0 tph) of 50 per-
cent FeSi is selected as the model plant to determine con-
trol costs. The open furnace exhausts 224 m /s at 230°C
(474,000 acfm at 450°F) to a cyclone recovery system. The
precleaned gas stream contains 290 kg/h (630 Ib/hr) of par-
ticulate matter, assuming 80 percent efficient cyclones.
Lead content of the particulate is not known. The gases
enter a shaker-type fabric filter designed to handle 200
m3/s at 177°C (422,000 acfm at 350°F) at a filter velocity
of 0.8 cm/s (1.6 fpm). A 3000-hp fan system provides adequate
suction at a system pressure drop of 6.3 kPa (25 in. W.G.).
This control technique will reduce particulate emissions to
below the 6.8 kg/h (15 Ib/hr) average state limitation, by
maintaining over 99 percent efficiency.
Capital costs for the above control system are esti-
mated at $6.36 million, including cyclones, fabric filter,
fan system, and ductwork.
Annualized costs are estimated at $2.43 million in-
cluding utilities, maintenance, labor, overhead, and fixed
costs (with capital recovery). Most of the collected solids
are recycled through the process; however,the recovery
credit is not included in the annual costs. Annual operating
time is assumed at 8000 hours and annual labor is estimated
at 6000 hours.
See Section 2.9 and Appendix B for discussion of cost analyses
Detailed cost studies are available from EPA upon request.
4-270
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The capital and annualized costs are expressed below in
terms of exhaust volume and annual labor hours:
S.I. units
Capital, $ = 2.47 x 105V°'6
0.6
Annualized, $ = 2895V + 64,800V + 19.6H
V = m3/s at 230°C
H = annual labor hours
75 < V < 670
range
English units
Capital, $ = 2500 Q°*6
Annualized, $ = 1.37Q + 655Q0-6 + 19.6H
Q = acfm at 450°F
H = annual labor hours
1.6 x 105 < Q < 1.4 x 106
range
4.5.3,5 Impacts
A. Emission Reduction
Particulate emission reduction achieved by employing
emission control systems on electric arc furnaces range from
170 to 600 kg/Mg (340 to 1200 Ib/ton) of product (see Table
4-48). Lead content of emissions from the production of
ferroalloys can range from 100 to 10,000 ppm.
4-271
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B. Energy Impact
The power requirements for the 30 MW model furnace
producing 6.35 Mg/h (7.0 tph) of 50 percent FeSi are 15
GJ/Mg (15 MM Btu/ton) of product. The venturi scrubbing
system operating at 6.3 kPa (25 in. WG) pressure drop,
requires 1.1 GJ/Mg product (1.1 MM Btu/ton)f a 7 percent
increase in energy demand. The total energy requirements to
produce ferroalloys is not available.
C. Wastewater Impact
The amount of wastewater generated by the production of
ferroalloys ranges from 0.7 to 2.6 m /Mg product (3000 to
32
11,000 gal/ton) with wet scrubber controls. The scrubber
water discharge is estimated at 0.7 m /Mg (300 gal/ton).
D. Solid Waste Impact
No data relative to solid waste production is available
for ferroalloy plants. Emission control systems will gene-
rate 170 to 600 kg/Mg (340 to 1200 Ib/ton) depending on the
product. Most solid wastes can be recycled to the furnace
and therefore, there will be no significant increase in
solid waste.
4-272
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4.5.4 References for Section 4.5
1. Communication with Mr. Don Dussy. U. S. Bureau of
Mines. Washington, D. C. July 12, 1976.
2. Compilation of Air Pollutant Emission Factors. 2nd
Edition. U. S. Environmental Protection Agency.
Research Triangle Park, N. C. Publication AP-42.
February 1976.
3. Kalika, P. et al. Measurement of Fugitive Emissions.
The Research Corporation of New England. Presented
at the 1975 APCA Mtg. Boston, Massachusetts. Paper
No. 75-253. June 1975.
4. Weisburg, M. I. Field Operations and Enforcement
Manual for Air Pollution Control. Vol. III. Pacific
Environmental Services, Inc. Santa Monica, California.
For U. S. Environmental Protection Agency. EPA 70-122.
August 1972.
5. Danielson, J. A. (ed). Air Pollution Engineering
Manual. Second Edition. Air Pollution Control
District of Los Angeles. For U. S. EPA. Research
Triangle Park, N. C. May 1973. 987 p.
6. Systems Analysis of Emissions and Emissions Control
in the Iron Foundry Industry. A. T. Kearney and Co.,
Inc. Chicago, Illinois. For U. S. Environmental
Protection Agency. Division of Process Control
Engineering. Contact No. CPA 22-69-106. February
1971.
7. Economic Impact of Air Pollution Controls on Gray
Iron Foundry Industry. U. S. Dept. HEW. National
Air Pollution Control Association. Raleigh, N. C.
November 1970. 124 p.
8. Davis, W. E. Emission study of Industrial Sources
of Lead Pollutants. 1970. W. E. Davis and Associates.
Leawood, Kansas. U. S. Environmental Protection Agency,
EPA Contract No. 68-02-0271. April 1973. 123 p.
9. Kistler, J. Two Modern Methods for Abating Air
Pollution in Foundries and Iron and Steel Works.
Giesserei Dusseldorf. 43 (13): 333-340. June 1956.
Text in German.
4-273
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10. Drake, J. F. et al. Iron Age. 163 (12). 1949. pp. 88-92,
11. Control Program Guideline for Industrial Process Fugitive
Particulate Emissions. Preliminary Draft.^ PEDCo-
Environmental Specialists, Inc. Cincinnati, Ohio.
EPA Contract 68-02-1375. Task No. 33. December 10, 1976.
12. National Emission Data System (NEDS). U. S. Environmental
Protection Agency. Research Triangle Park, N. C.
Updated May 1975.
13. Exhaust Gases from Combustion and Industrial Processes.
Engineering Sciences, Inc. Washington, D. C. For U. S.
Environmental Protection Agency. Office of Air Programs.
Durham, N. C. Contract No. EHSD71-36. October 2, 1971.
14. Billings, C. E. (ed). Fabric Filter Manual. The
Mcllvaine Company. Northbrook, Illinois. November 1975.
15. Nichols, G. B. (ed.) Electrostatic Precipitator Manual.
The Mcllvaine Company, Northbrook, Illinois. February
1976.
16. The Mcllvaine Scrubber Manual. The Mcllvaine Company
Northbrook, Illinois. 1974.
17. Hardi.nscn, L. C. and H. R. Herrington. Study of
Technical and Cost Information for Gas Cleaning Equipment
in the Lime and Secondary Non-ferrous Metallurgical
Industries. Industrial Gas Cleaning Institute. Rye,
New York. For U. S, Environmental Protection Agency.
Research Triangle Park, North Carolina. Contract EPA
70-150. December 31, 1970. 293 p.
18. Communication with Mr. H. T. Reno. Iron and Steel
Branch Chief. Bureau of Mines. Washington, D. C.
October 12, 1976.
19. Varga, J. Jr., and H. W. Lownie. Final Technological
Report on A Systems Analysis Study of the Integrated
Iron and Steel Industry. Battelle Memorial Institute,
Columbus, Ohio. May 1969.
20. Katari, V. S. and Gerstle, R. W. , Iron and Steel Industry,
PEDCo-Environmental Specialists, Inc., Contract No. 68-
02-1321, Task No. 26, December 1975.
4-274
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21. The Making, Shaping and Treating of Steel, Ninth Edition.
McGannon, H. E. (ed.) Pittsburgh, Pennsylvania, U. S.
Steel Company, 1971.
22. Iron and Steel Mills. In: Compilation of Air Pollution
Emission Factors. Environmental Protection Agency.
Contract Number CPA-22-69-119. April 1973. p. 7.5-4
and 7.5-5.
23. Yost, K. J. et al. Purdue University. Flow of Cadmium
and Trace Metals. Volume I. National Science Foundation.
Project No. PB-229478. June 30, 1973.
24. Metallurgical Coke Manufacturing. In: Compilation of
Air Pollutant Emission Factors. Environmental Protection
Agency, Research Triangle Park, N. C. Contract Number
CPA-22-69-119. April 1973. p. 7.2-2.
25. Jacko, R. B., Neuendorf, D. W., and Blandford, J. R.,
The By-Product Coke Oven Pushing Operation: Total and
Trace Metal Particualte Emissions, Purdue University,
#76-12.2 June 27, 1976 presentation.
26. Weekly Coal Report, No. 3056, Mineral Industry Surveys,
U. S. Department of the Interior.
27. Abernathy, R. F., Peterson, M. J., and Gibson, F. H.,
Spectrochemical Analysis of Coal Ash for Trace Elements,
Bureau of Mines, RI7281, July 1969.
28. Barnard, P. E. et al. Recycling of Steelmaking Dusts,
Bureau of Mines Solid Waste Program, Technical Progress
Report - 52, Feb. 1972.
29. Background Information for the Development of New
Source Performance Standards for Iron and Steel Industry.
U, S. Environmental Protection Agency, Research Triangle
Park, N. C.
30. Project Independence. Energy Conservation in the Manu-
facturing Sector. 1954-1990. Prepared by Interagency
Task Force on Energy Conservation. Federal Energy
Administration. Volume 3. U.S. GPO. Washington, B.C.
November 1974.
31. Mantell, C.L. Solid Wastes. Origin, Collection, Pro-
cessing and Disposal. John Wiley and Sons, New York,
New York. 1975.
32. Sittig, M. Environmental Sources and Emissions Handbook.
Noyes Data Corporation. Park Ridge, New Jersey. 1975.
4-275
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33. Lund, H.E. Industrial Pollution Control Handbook.
McGraw-Hill Book Co., New York, New York. 1971.
p. 10-1.
34. Matthews, N. A. Ferroalloys, Preprint from the 1974
Bureau of Mines Mineral Yearbook. U. S. Department of
Interior. Bureau of Mines. Washington, D. C. 1974.
35. Katari, V. S. Trace Pollutant Emissions from the
Processing of Metallic Ores. PEDCo-Environmental
Specialists, Inc. Cincinnati, Ohio. For U. S.
Environmental Protection Agency. Contract No. 6802-
1321. Task 4. 1974.
36. Vandegrift, A. E. et al, Particulate Pollutant System
Study - Mass Emissions. Volumes 1, 2, and 3. U. S.
Environmental Protection Agency. Durham, N. C. PB-
203-128, PB-203-522 and PB-203-521. May 1971. 500 pp.
37. Sansom, R. L. Development Document for Proposed Effluent
Limitations, Guidelines and New Source Performance
Standards for the Smelter and Slag Processing Segment
of the Ferroalloy Manufacturing Point Source Category.
Environmental Protection Agency, Contract No. 440/1-
73-008, August 1973.
38. Background Information for the Development of New Source
Performance Standards for Electric-Submerged Arc Furnaces
for Production of Ferroalloys. U. S. Environmental
Protection Agency, Research Triangle Park, N. C. EPA-450/
2-74-018. May 1974.
39. Kertcher, L. F., and Linsky, B. Economics of Coke Oven
Charging Controls. JAPCA, 24(8). August 1974. p. 765.
40. Dealy, J.O. and A.M. Killin. Engineering and Cost Study
of the Ferroalloy Industry, Appendix E. U.S. Environ-
mental Protection Agency. Research Triangle Park, N.C.
EPA-450/2-74-008.
41. EPA Test No. 72-PC-02. Emission Measurement Branch.
Environmental Protection Agency. Research Triangle
Park, North Carolina. 1972
42. Atmospheric Lead Emissions Ferroalloy Production.
Statement by Ferroalloys Association to National Air
Pollution Control Techniques Advisory Committee
Meeting. March 2, 1977.
4-276
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43. Environmental Protection Agency. The Ferroalloys
Association Cooperative Study. Air Pollution Control
Engineering and Cost Study of the Ferroalloy Industry.
EPA-450/2-74-008. May 1974.
44. Emissions, Effluents, and Control Practices for
Stationary Particulate Pollution Sources. Midwest
Research Institute. Kansas City, Missouri. For
National Air Pollution Control Association. Cincinnati,
Ohio. Contract No. CPA 22-67-104. November 1, 1970.
607 pp.
4-277
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4.6 LEAD OXIDES AND PIGMENTS
Lead oxide is used primarily in the manufacture of
lead-acid storage batteries, but is also useful as a pigment
in paints and ceramic glazes. The lead oxides include
litharge (PbO), lead dioxide (Pb02), and red lead (Pb3O4).
Black oxide, the most widely used form of lead oxide, is
merely a mixture of litharge and finely divided metallic
lead. Red lead is the major lead pigment. Other lead
pigments include white lead, lead chromates, and leaded zinc
oxides.
Of nearly 431 Gg of lead oxide and pigments (475,000
tons) produced in the United States in 1975, approximately
2
70 percent was used in storage batteries as black oxide.
It is estimated that 112 Mg of lead (124 tons) was emitted
into the atmosphere by the manufacture of lead oxides and
3 4
pigments in 1975, ' not including fugitive emissions.
4.6.1 Process Description
4.6.1.1 Lead Oxides
A. Lead Monoxide; Most lead oxides and many of the major
lead pigments are derived from lead monoxide (PbO), in a
form called litharge. There are four principal processes
for producing high-grade litharge:
(1) Metallic lead is partially oxidized and milled to
a powder, which is charged into a reverberatory
furnace at about 590°C (1,100°F) to complete the
oxidation to ordinary "chemical litharge".
4-278
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(2) Pig lead is oxidized and stirred in a reverbera-
tory furnace or rotary kiln to form lead monoxide.
(3) Molten lead is run into a cupelling furnace held
at about 1020°C (1,800°F), and molten litharge is
produced.
(4) Molten lead at about 510°C (950°F) is atomized
into a flame where it burns vigorously, producing
"sublimed" or "fumed" litharge.5
In all cases, the product must be cooled quickly to
below 300°C (570°F) to avoid formation of red lead.5
B. Black Oxides; Black oxide contains 60 to 80 percent
litharge, the remainder being finely divided metallic lead.
It is used exclusively in the manufacture of lead-acid
storage batteries. Black oxide is usually produced in the
same furnace in which the litharge is produced by either the
ball mill process or the Barton process. In both processes,
the oxidation reaction is as follows:
2 Pb + 02 -»• 2 PbO
The ball mill process is shown in Figure 4-48. In this
process, heat generated by tumbling solid lead ingots in a
mill is used to initiate oxidation. The amount of air
passing through the mill, the temperature of the charge and
the weight of the charge are controlled to produce the
desired ratio of lead oxide to finely divided metallic lead.
Centrifugal mills and/or cyclones are used to collect large-
sized particles, whereas the fine-particles are collected
with baghouses.
4-279
-------
Figure 4-48. Ball mill process for
lead oxide manufacture.
LEAD
FEED
PRODUCT TO STORAGE
Figure 4-49. Barton pot process for
g
lead oxide manufacture.
4-280
-------
In the Barton process, as shown in Figure 4-49, molten
lead is fed into a kettle and rapidly stirred while air is
drawn through the kettle to oxidize the lead. The typical
product recovery system consists of a settling chamber,
cyclone, and fabric filter.
C. Lead Dioxide; Lead dioxide is a vigorous oxidizing
agent used in a number of chemical process industries. It
decomposes to lower oxides rather easily, releasing oxygen.
It is commercially produced either by the treatment of an
alkaline red lead slurry with chlorine, or by anodic oxida-
tion of solutions of lead salts. The amount of lead dioxide
produced is insignificant and of no commercial importance.
4.6.1.2 Lead Pigments
A. Red Lead; Red lead, also called minium, is used prin-
cipally in ferrous metal protective paints. The manufacture
of red lead begins by charging litharge into a reverberatory
furnace held at 480 to 510°C (900 - 950°F). The process
consists of oxidation until a specified amount of lead
monoxide is converted to Pb3C>4. The 85 percent grade red
lead is made in about 24 hours under these conditions * A
typical red lead manufacturing plant will produce 27 Mg (30
tons) of red lead per day.
B. White Lead; The commercial varieties of white lead
include basic carbonate white lead, basic sulfate white
4-281
-------
lead, and basic lead silicate. Manufacture of basic car-
bonate white lead is based on the reaction of litharge with
acetic acid or acetate ions. The product of this reaction
is then reacted with carbon dioxide to form lead carbonate.
White leads other than, carbonates are made either by chemi-
cal or fuming processes. The chemical process is like that
described above except that other mineral dioxides are used
in place of carbon dioxide. The fuming process differs,
however, in that the product is collected in a baghouse
rather than by wet slurry filtration. Consequently, dryers
are not needed for these products. Only about 3.1 Gg of
2
white lead (3400 tons) was produced in 1975.
C. Lead Chromate: Chromate pigments are generally manu-
factured by precipitation or calcination. A commonly used
process is the reaction of lead nitrate solution with sodium
chromate solution:
Pb(N03)2 + Na2 (Cr04) = PbCr04 + 2NaN03
The lead nitrate solution can be made using either lead
monoxide or by reacting molten lead with nitric acid.
D. Leaded Zinc Oxides: Leaded zinc oxices are used
almost entirely as white pigments for exterior oil-base
paints. Leaded zinc oxides are produced either by smelting
and cofuming combinations of zinc and lead sulfide ores or
by mechanically blending separately prepared fractions of
zinc oxide and basic lead sulfate. The first process
4-282
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involves heating the two materials to produce a fume, which
is cooled and collected in baghouses. Only one company now
manufacturers leaded zinc oxides.
4.6.2 Emissions
4.6.2.1 Lead Oxides - The emission characteristics of the
i
ball mill and Barton processes, summarized in Table 4-51 are
typical of emissions from the manufacture of litharge, black
oxide, and lead dioxide. Based on an average lead emission
rate of 0.22 g/kg product (0.44 Ib/ton) and a production
2
rate of 454 Gg of litharge and black oxide (500,000 tons)
an estimated 100 Mg of lead (110 tons) was emitted into the
atmosphere by lead oxide production facilities in 1975.
4.6.2.2 Lead Pigments
A. Red Lead; Collection of dust and fume emissions from
the production of red lead is an economic necessity.
Consequently, particulate emissions are small. Particulate
emissions after baghouse collectors are about 0.5 g/kg
4
product (1.0 Ib/ton). Since only lead monoxide and oxygen
go into the production of red lead, about 90 percent of the
particulate emissions is assumed to be lead. Approximately
2
17.6 Gg (19,400 tons) of red lead was produced in 1975,
resulting in the emission of 7.9 Mg of lead (8.7 tons) into
the atmosphere.
4-283
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Table 4-51. CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM LEAD OXIDE BALL MILL AND BARTON POT PROCESSES
Parameters
Gas flow rate
Temperature
Grain loading
Particle size
distribution, a
wt %
Lead emission
factor*5
Standard
international
units
1.2 m3/s-Mg-h~1
Pb charged
120°C
7-11 g/m3
0 to 1 ym - 4%
1 to 2 ym - 11%
2 to 3 ym - 23%
0.22 g/kg
product
English
units
2300 acfm/tph
Pb charged
250°F
3-5 gr/scf
0 to 1 ym - 4%
1 to 2 ym - 11%
2 to 3 ym - 23%
0.44 Ib/ton
product
References
2
2
8
8
Baghouse catch.
Emissions are after baghouse. Baghouse considered process
equipment.
4-284
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B. White Lead: Data on emissions from the production of
white lead pigments are not available. Because of health
and safety regulations, however, it is believed that white
lead pigment production emits about 0.28 g Pb/kg product
(0.55 lb/ton).4 The production of 3.1 Gg of white lead
2
(3400 tons) resulted in total emissions of less than 0.9 Mg
of lead (1 ton) during 1975.
C. Lead Chromates: A chrome pigment facility producing
54 Mg of pigments per day (60 tons) emits approximately 65 Mg
Pb/kg of chrome pigment produced (0.13 lb/ton). The emissions
from the dryer exhaust scrubbers account for over 50 percent
of the total lead emitted in the lead chromate production.
Hence, the 1975 lead emissions are estimated at approximately
3.0 Mg (3.3 tons) based on 45.4 Gg of chrome pigment (50,000
2
tons) produced.
For occupational health reasons, OSHA dust control
requirements may increase the lead chromate emissions with
a larger volume of lower lead concentration in the exhaust.
Many of the lead chromate plants are old and were built before
extensive emission controls were necessary.
D. Leaded Zinc Oxides: Data on emissions are not avail-
able. In view of the limited production capacity of this
pigment, lead emissions are believed to be insignificant.
4.6.3 Control Techniques
Fabric filters, often preceded by dry cyclones or
settling chambers, are the almost universal choice for
4-285
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collecting lead oxides and pigments. Several of the manu-
facturers incorporate filters as an integral part of the
process; hence, the emission factor is based on lead emissions
from the filter. In addition, the pigment manufacturing
processes are generally well-controlled for economic and
health reasons since the value of the recovered products
often exceeds the cost of collecting them.
Fabric filters provide the most economical means for
Q
high-efficiency emission control. Cooling of the exhaust
gases during production of the lead oxides and pigments is
often accomplished with dry cyclones and settling equipment
which are used to capture larger particles, ahead of the
filter. Dacron bags, which will operate at temperatures up
to 150 C (300 F), have been used effectively in lead oxide
processes. Shaker-type baghouse filters are used primarily,
generally requiring filter velocities as low as 0.5 to 1.3
cm/s (1 to 2.5 fpm) . Collection efficiencies of baghouse
filters exceed 99 percent.
In some cases, a fabric filter may not be appropriate
and a scrubber is used resulting in higher emissions.
Scrubbers are required on the dryer exhaust because of the
dryer's moist steam-laden air which would clog a bag filter.
The scrubber efficiencies range from 70 to 95 percent effective.
Table 4-52 indicates the performance of fabric filter
systems on lead oxide mills.
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Table 4-52. PERFORMANCE TEST RESULTS ON FABRIC FILTER SYSTEMS
SERVING LEAD OXIDE FACILITIES8
i
ro
CO
Control system
Test point
Particulate emissions
g/m3
gr/dscf
gr/kg product
Ib/ton product
Lead emissions
g/m3
gr/dscf
g/kg product
Ib/ton product
Barton pot
Settling chamber/
cyclone/fabric filter
Outlet
0.074-0.13
0.032-0.056
0.21-0.43
0.41-0.85
0.055-0.11
0.024-0.046
0.15-0.35
0.30-0.69
Hammer mi 11
furnace
Cyclone/
fabric filter
Outlet
0.028
0.012
0.028
0.057
0.018
0.003
0.021
0.042
Hammermill
furnace
Cyclone/
fabric filter
Inlet to
filter
75.7
32.9
69.7
30.3
Loading
operations
Fabric
filter
Outlet
0.0067
0.0029
0.0094
0.0041
Auxilary
furnace
operations
Fabric
filter
Inlet
7.55
1.11
2.46
1.07
Auxilary
furnace
operations
Fabric
filter
Outlet
0.0023
0.0010
0.00035
0.00015
-------
4.6.3 Control Costs
A ball mill process with a throughput capacity of 1.9
Mg/h (2.1 tph) of lead, exhausts 2.1 m3/s at 120°C (4400
acfm at 250°F) to a settling chamber, cyclone, and fabric
filter. Uncontrolled lead emissions are estimated at 45
kg/h (100 Ib/hr). The mechanical shaker-type fabric filter
t*
(equipped with Dacroir bags) is designed to handle 2.1 m /s
(4400 acfm) at a filter velocity of 1 cm/s (2 fpm). The 15
hp fan system is rated at 2.1 m /s (4400 acfm) at a system
pressure drop of 3 kPa (12 in. W.G.). This control technique
can meet the average state particulate regulation of 3.2
Kg/h (7.0 Ib/hr) by maintaining an efficiency of more than
99 percent.
Total capital costs for the above system are estimated
at $58,000, including settling chamber, cyclone system,
fabric filter, fan system, and ductwork.
Total annualized costs are estimated at $32,300, in-
cluding utilities, labor, maintenance, overhead, and fixed
costs (with capital recovery). Annual operating and labor
hours are assumed at 6000 and 750 hours, respectively. The
value of the material recovered is considerably greater than
the annualized costs„ Assuming $0.09/kg ($0.20/lb) of lead
oxide recovered, a total annual credit of $119,000 is realized.
Therefore, there is a net savings for installing a fabric
filter.
a
See Section 2.9 and Appendix B for discussion of cost analyses
Detailed cost studies are available from EPA upon request.
4-288
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Capital and annualized costs are given below in terms
of exhaust volume and annual labor hours. These cost equations
do not include credit for product recovery.
S.I, units
Capital, $ = 37,400 V°'6
Annualized, $ = 1210V + 9800 V°'6 + 19.6H
V = m3/s at 120°C
H = annual labor hours
0.7 < V < 6
range
English units
Capital, $ = 378 Q°'6
Annualized, $ = 0.57Q + 99Q°*6 + 19.6H
Q = acfm at 250°F
H = annual labor hours
1500 < Q < 13,000
range
4.6.4 Impacts
Lead oxide production is unique in that fabric filter
systems are used as process equipment in order to recover the
lead product. Additional control devices could be needed in
certain cases to reduce lead emissions, although this appears to
be an exception to the general case. Typically, therefore, no
energy or environmental impacts can be directly attributed to
the control of particulate or lead emissions.
4-289
-------
4.6.5 References for Section 4.6
1. Ritchie, E.J. Lead Oxides. Largo, Florida. Indepen-
dent Battery Manufacturers Association, Inc. 1974.
p. 13.
2. U.S. Department of the Interior. Bureau of Mines.
Washington, B.C. 1975.
3. Background Information For Support of the Development
of Performance Standards for the Lead-Acid Battery
Industry-Interim Report No. 2. PEDCo-Environmental
Specialists, Inc. Cincinnati, Ohio for U.S. Environ-
mental Protection Agency. EPA Contract No. 68-02-2085.
December 1975. pp. 1-18-1-22, 6-7.
4. Beltz, P.R. et al. Economics of Lead Removal in
Selected Industries. Battelle Columbus Laboratories,
Columbus, Ohio. Environmental Protection Agency, 1973.
pp. 7-42, 53-70.
5. Davis, W.E. Emissions Study of Industrial Sources of
Lead Air Pollutants 1970. W.E. Davis & Associates
Leawood, Kansas for U.S. Environmental Protection
Agency. EPA Contract No. 68-02-0271. April 1973.
p. 123.
6. Nance, J.T. and K.D. Luedtke. Lead Refining, In: Air
Pollution Engineering Manual, Danielson, J.A. (ed.),
Research Triangle Park, North Carolina. Environmental
Protection Agency. May 1973. p. 304.
7- Thompson, A.P. Lead Compounds. In: Kirk-Othmer
Encyclopedia of Chemical Technology. Standen, A.
(ed.). New York City, John Wiley & Sons, Inc. 1967.
p. 266-282.
8. Test No. 74-PBO-l. Emission Testing Branch. Environ-
mental Protection Agency. Research Triangle Park,
Nort'i Carolina. Contract No. 68-02-0226, Task No. 10.
August 20-31, 1973.
9. Crane, G.B. Control Techniques of Lead Emissions,
Draft. Environmental Protection Agency. Research
Triangle Park, North Carolina. February 1971. p. 4-41,
4-290
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4.7 PESTICIDES
The only pesticide containing lead is lead arsenate
(PbHAsO.). It was most widely used during World War II, but
demand began to drop soon after the war due to competition
from organic insecticides. The cancellation of pesticide
regulations in 1968 and 1969.- and tightened OSHA restrictions
on pesticide manufacturing because of the health effects of
arsenic on workers, accelerated the decline of its use in
recent years. The annual production of lead arsenate from
1960 through 1972 ranged from 1.88 to 4.5 Gg (2070 to 4960
tons). There were no production or imports of lead arsenate
in 1975, and there were no suppliers found who dealt in more
than small quantities for research purposes. It is there-
fore assumed that no lead emissions were generated from this
source category during 1975.
Reference
1. Technical and Microeconomic Analysis of Arsenic and Its
Compounds. EPA 560/6-76-016. Office of Toxic Sub-
stances. U.S. EPA. April 12, 1976.
4-291
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4.8 LEAD HANDLING OPERATIONS
Lead handling operations include preparation of type
metal, can soldering, and cable covering. Estimated 1975
emissions of lead from these sources is 611 Mg of lead (675
tons), representing over 8 percent of the total industrial
lead emissions, not including fugitive emissions.
4.8.1 Type Metal
Lead type is used primarily in the letterpress segment
of the printing industry. The lead typemaking processes are
classified according to the methods of producing the final
product: linotype, monotype, and stereotype. Approximately
14.74 Gg of lead (16,211 tons) was consumed by type .metal
processes in 1975, resulting in lead emissions of about 435
Mg (480 tons).
4.8.1.1 Process Description - Figure 4-51 shows a typical
material flow diagram of a type metal operation. Linotype
and monotype processes produce a mold, and the stereotype
process produces a plate for printing. All hot-metal
typemaking processes are closed-cycle. The type is cast
from a molten lead alloy and then remelted after printing.
A small amount of virgin metal is added periodically to the
melting pot to adjust the alloy and to fill make-up require-
ments. Although the validity of the information is question-
able, one stereotype plant reported a loss of 58 kg (127 Ib)
4-292
-------
DROSS
U)
MAKE-UP ALLOY
USED TYPEMETAL
CASTING
CAST METAL
TRIMMING
AND FINISHING
LEAD TYPE
PRINTING (STEREOTYPE)
OR MOLD MAKING
(LINOTYPE & MONOTYPE)
RECYCLED METAL
Figure 4-50. Flow diagram for type metal processes.
-------
of metal by dressing after remelting 4.1 Mg (9,000 Ib) of
metal 11 times.2 The average metal loss would then be 0.13
percent per melt.
All type metal is an alloy consisting mainly of lead
with much smaller amounts of antimony and tin. Each con-
stituent provides a desired metallurgical characteristic for
a slug (a solid bar with raised letters in a line) or other
form of type-casting. Lead constitutes 60 to 85 percent of
the type metal because it has a low melting point. Antimony
lends hardness to the alloy and minimizes contraction as the
metal cools. The antimony expands as the slug solidifies,
providing a clear type face. Tin gives both strength and
fluidity to the type metal and provides a smooth and even
surface to the slug.
4.8.1.2 Emissions - The melting pot is the major source of
emissions. Melting the "dirty" metal plates containing
printing ink, paper, and other impurities generates smoke,
which contains hydrocarbons as well as lead particulates.
Only small quantities of particulates are created by oxida-
tion after the meltdown of lead because of the protective
layer of dross on the metal surface. From limited test
3 4
data, ' it is estimated that 35 percent of the total
emitted particulate is lead.
4-294
-------
Transferring and pouring of molten metal at high
temperature into the molds involves surface oxidation of the
metal and may also produce oxidized fumes.
The trimming and finishing operations emit lead par-
ticles. Particle size is large, and the particles tend to
settle out in the vicinity of the trimming saws and finishing
equipment.
Lead consumption for this industry is difficult to
determine. The U.S. Bureau of Mines reported the 1975 type
metal consumption cited earlier, 14.74 Gg (16.2 tons). This
total, however, does not include type metal sales from
newspapers or other printing operations abandoning the type
metal process. One study estimates consumption of 17.2 Gg
of type metal (19,000 tons) in 1976. On the basis of a
metal recycle-to-replacement ratio of 330, the total lead
recycled in the industry for 1976 would be 5.7 Tg (6.3 x 10
4
tons).
Approximately half of the current lead type operations
control lead emissions by about 80 percent; the other opera-
tions are uncontrolled. Although the 1975 lead emissions
from the industry are estimated at 436 Mg (481 tons), the
emissions are expected to decline to less than 9 Mg of lead
(10 tons) per year by 1985, primarily because improved
printing techniques. Based upon the values cited, the lead
emission factor for this industry is 0.13 g/kg of lead
processed (0.25 Ib/ton).
4-295
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4.8.1.3 Control Techniques - The most frequently controlled
sources at hot metal printing facilities are the main
melting pots and dressing areas. During dressing, hood
doors are opened and pot emissions enter the plant atmo-
sphere unless vented to a control device or to the outside.
Linotype melting pots and finishing equipment do not require
emission controls when they are operated properly. Emission
n
control devices in current use are Type-N Roto-Clones , wet
scrubbers, fabric filters, and electrostatic precipitators.
These can be used in various combinations.
Activated carbon filtering devices were originally
installed to trap hydrocarbons and prevent fires in the
P
exhaust system ducts. Roto-Clones are also sufficient for
this purpose. Within the last 5 years there has been
concern about visible emissions, primarily caused by hydro-
carbons, from the stacks of newspaper plants. Some plants
have added controls to eliminate these visible emissions.
While removing hydrocarbons, these control systems also
remove some of the heavier particulates that contain lead.
4.8.2 Can Soldering
Metal can production in 1975 was estimated at 179
million base-boxes. A base-box is equivalent to 20.23 m2 of
surface area (217.8 ft2). Fifty percent of the total can
market consists of beverage cans. The beverage can market
4-296
-------
consists of one-half seamless two-piece aluminum cans and
one-half conventional steel three-piece soldered cans.6
Therefore, 44.8 million base-boxes of nonsoldered aluminum
cans and 134 million base-boxes of soldered steel cans were
produced. A total of 63 Mg of lead (70 tons) was emitted to
the atmosphere in 1975, assuming no emission control.
4.8.2.1 Process Description - Side seams of cans are
soldered on a machine consisting of a solder-coated roll
operating in a bath of molten solder, typically containing
98 percent lead. The roll revolves, bringing molten solder
up to the seam of the can which is moving rapidly along a
roll parallel to the axis of the solder roll. After the
soldering, the excess is wiped from the joint by a rotating
cloth buffer, which creates some dust.
4.8.2.2 Emissions - Hoods, exhaust ducts, and cyclone
collectors are used to collect the dust, but some dust
escapes the system. Particles entering the system are in
flake form, mostly about 1.3 cm (0.5 in.) diameter. Parti-
cles exhausted to the atmosphere are on the order of 20
microns or smaller. When using solder averaging 40 percent
lead, one large manufacturer reported lead emissions to the
atmosphere of 0.9 g/kg of solder consumed (1.7 Ib/ton).
Several emission tests indicate that lead content of
the particulate emissions is 3 to 38 percent, with an average
4-2D7
-------
emission factor of 0.16 Mg of lead (0.18 ton) per million
base boxes.
One source reports an uncontrolled lead emission
factor of 3.6 g/kg of lead in the product (7.1 Ib/ton);
another source reports a factor of 1.5 g/kg of lead in the
product (3.0 Ib/ton). If 50 percent of the total 51.7 Gg of
lead (57,000 tons) used in solder applications were uti-
lized in can manufacturing, these data would indicate an
emission factor of 0.36 to 0.72 Mg of lead (0.4 to 0.8 ton)
per million base-boxes of soldered cans produced.
These values indicate that the lead emission factor for
can soldering operations ranges from 0.18 to 0.73 Mg (0.2 to
0.8 ton) per million base-boxes produced, with an average of
0.45 Mg (0.5 ton) per million base-boxes. At a production
Q
level of 134 million base-boxes and assuming no control,
the estimated lead emissions for 1975 are approximately 63
Mg (70 ton) .
4.8.2.3 Control Techniques - Mechanical cyclones may be
provided to collect the large flakes generated at the wiping
station. Efficiencies of 75 percent or more are achieved.
Some local regulations require control of visible
emissons from the solder bath. Maintaining a good flux
cover is the most effective means of controlling lead
emissions.
4-29P
-------
Low-energy wet collectors or fabric filters can also be
installed to control lead emissions; these emissions, how-
ever, do not appear to be serious enough to warrant high-
efficiency control.
4.8.3 Cable Covering
Lead cable coverings are of two types, the permanent
lead sheath and the temporary lead-cured jacket. About 10
percent of the lead cable covering produced in the U.S. is
on lead-sheathed cables and about 90 percent on lead cured
jacketed cables. Consumption of lead by these processes in
1975 was 45.50 Gg (50,000 tons).11 A survey of four major
producers indicates a throughput to consumption ratio of
about 10, which suggests that about 455 Gg (500,000 tons) of
lead was processed. The total lead emissions for 1975 are
estimated at 113 Mg (125 tons).
4.8.3.1 Process Description - In the preparation of lead-
cured jackets, an unalloyed lead cover, which was applied in
the vulcanizing treatment during the manufacture of rubber-
insulated cable, is stripped from the cable and remelted.
Lead coverings are applied to insulated cable by
hydraulic extrusion of solid lead around the cable as shown
in Figure 4-51. Molten lead is continuously fed into the
press where it solidifies as it progresses through. A
diagram of an extruder, or screw press, is shown in Figure
4-52.
4-299
-------
PISTON
CHANNELS FOR
COOLING WATER
DIE
BLOCK
CABLE ^777
CORE
CORE TUBE-
ADJUSTING NUT
CORE TUBE
CYLINDER
BLOCK
DIE-
ADJUSTING
SHEATH
FINISHED
CABLE
Figure 4-51. Cross section of a hydraulic extrusion press.
. V
\
J\
pj\
V\xv
v}\
V^
v\c
_VX
i — V;:)
v
V
V
\
(Vt:
v\
>\
__
MFI TTNR 70NE
1
k
HOLDING
ZONF
C^
Hi:
\
n^
•• — ±t
3
Figure 4-52. Screw-type extrusion press.
4-300
10
-------
4.8.3.2 Emissions - Extrusion rates for typical presses are
1.3 to 6.8 Mg/hr of lead (3,000 to 15,000 Ib/hr). A lead
melting kettle supplies lead to the press, which is heated
either electrically or with a combustion-type burner.
Vapors from these kettles are exhausted to the atmosphere.
The melting kettle is the only source of atmospheiic lead
emissions and is generally uncontrolled.
Emission data are scarce and questionable. Two EPA
source tests show lead emission rates of about 25 mg/kg of
12
lead extruded (0.05 Ib/ton); two manufacturers have
estimated rates of 0.75 to 2.5 g/kg (1.5 to 5.0 Ib/ton).
Assuming an emission factor of 0.25 g/kg (0.5 Ib/ton) of
lead extruded gives estimated 1975 lead emissions of 113 Mg
(125 tons). A typical cable covering operation exhausts 1.4
m /s (3000 cfm) at less than 38°C (100°F). Average particle
size is approximately 5 ym. Lead content of the particu-
7 12
late emissions is about 70 to 80 percent. '
4.8.3.3 Control Techniques - Cable covering processes
usually do not incorporate particulate collection devices.
If control is desirable, fabric filters can be installed to
attain efficiencies of 99.9 percent. A rotoclone type wet
collector can attain an efficiency of 75 to 85 percent and a
dry cyclone collector can reduce lead emissions by 45 per-
cent or more.
4-301
-------
Process modifications to minimize emissions include
lowering and controlling the melt temperature, enclosing the
melting unit to permit lower air flow rates, and using
fluxes to provide a cover on the melt.
4-302
-------
4.8.4 References for Section 4.8
1. U.S. Bureau of Mines. Conversation with J.P. Ryan.
Washington, D.C. June 17, 1976.
2. Typesetting Machines and Type Metal. Twentieth Century
Encyclopedia of Printing- Graphic Arts Publishing
Company. Chicago. 1930. pp. 230-231.
3. Source Test. Detroit News. Wayne County Department of
Health, Air Pollution Control Division. Detroit.
1970.
4. Source Test. San Francisco Newspaper Printing Company.
San Francisco. April 13-14, 1975.
5. Atmospheric Emissions from Lead Typesetting Opera-
tions - Screening Study. Prepared by PEDCo-Environ-
mental Specialists, Inc. for U.S. Environmental Protec-
tion Agency, Research Triangle Park, North Carolina.
Contract No. 68-02-2085. 75 p.
6. U.S. Industrial Outlook 1976 with Projections to 1980.
U.S. Department of Commerce. Domestic and International
Business Administration. U.S. GPO. Washington, D.C.
January 1976. 465 p.
7- Davis, W.E. Emission Study of Industrial Sources of
Lead Air Pollutants, 1970. W.E. Davis & Associates.
Leawood, Kansas. For U.S. Environmental Protection
Agency. Contract No. 68-02-0271. April 1973. 123 p.
8. Confidential Test Data. PEDCo-Environmental Special-
ists, Inc. Cincinnati, Ohio.
9. Hopper, T.G. and W.A. Marrone. Impact of New Source
Performance Standards on 1985 National Emissions from
Stationary Sources. Volume 1. The Research Corpora-
tion of New England. Wethersfield, C.N. For U.S.
Environmental Protection Agency. Research Triangle
Park, North Carolina. Contract No. 68-02-1382. Task
3. October 24, 1975.
4-303
-------
10. Beltz, P.R. et al. Economics of Lead Removal in
Selected Industries. Battelle Columbus Laboratories.
Columbus, Ohio. Prepared for the U.S. Environmental
Protection Agency. Contract No. 68-02-0611. Task No.
3. August 31, 1973.
11. Private Communication with J.R. Ryan. U.S. Bureau of
Mines. Washington, D.C. June 17, 1976.
12. Shea, E.P. Emissions from Cable Covering Facility.
Midwest Research Institute. EPA Contract No. 68-02-0228,
Task No. 31. June 1973.
4-304
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4 . 9 MISCELLANEOUS SOURCES OF LEAD
Portland cement production, metallic lead products, and
lead glass manufacture caused the emission of about 445 Mg
(491 tons) of lead in 1975, not including fugitive emissions,
representing 6 percent of the total industrial lead emissions,
Over 180 Gg (200,000 tons) of lead was consumed by the lead
glass and metallic lead products industries.
4.9.1 Cement Production
7
Approximately 65 Tg of cement (7.2 x 10 tons) was
produced in 1975 by two major methods identified as dry and
wet processes. Production of Portland cement by the dry
process was 35.8 Tg (3.95 x 10 tons) and caused emissions
of 188 Mg (207 tons) of lead. Production by the wet process
was 29.5 Tg (3.25 x 10 tons) and the lead emissions are
estimated at 124 Mg (137 tons).
4.9.1.1 Process Description - In the dry process, the raw
materials (limestone, cement rock, clay, and iron ore) are
ground, crushed, blended, and then fed to a kiln to form
clinker, after which gypsum is added and the final mix is
ground to form Portland cement. In the wet process, water
is added to the initial blend of raw materials before
grinding. This material is fed into a kiln in the form of a
slurry. Lead is an incidental trace element in the raw
materials of both processes. The three major sources of
4-305
-------
particulate and lead air pollutants are the kilns, dryers,
and grinders.2 Figure 4-53 depicts the flow of materials,
process equipment, and emission points in a typical cement
plant.
A. Kilns and Clinker Coolers: At the heart of every cement
plant is the cylindrical rotary brick-lined kiln, as shown
in Figure 4-54, which is the largest single source of par-
ticulate emissions. Kilns range in size from 1.8 to 7.6 m
(6 to 25 feet) in diameter and from 18 to 232 m (60 to 760
feet) in length. Typically, large plants can produce
4500 Mg per day (5000 tpd) and small plants about 450 Mg
per day (500 tpd) of cement. Kilns may be fired with oil,
natural gas, or coal; temperatures exceed 1400°C (2600°F).
In the burning process about one-third of the dry weight
of the feed is lost. In the hot zone, 20 to 30 percent of
the charge is converted to liquid, through which the
chemical reactions proceed. Water is first evaporated in
the upper part of the kiln. In the middle of the kiln,
CO2 and combined water are driven from the raw materials
to form calcium silicates, aluminates, and ferrites. The
lower third of the kiln is the burning zone, maintained
at temperatures near 1500°C (2700°F) . The clinker product
appears in the form of round, marble-sized balls.3 The
product then passes through the clinker cooler.
4-306
-------
*>.
I
U)
o
I AIR
[SEPARATOR J
DRY PROCESS
1 GRINDING
MILL
AIR
HOT AIR
FURNACE
BUNDING
SILOS
WOUND
STORAG!
Y
SlUWY
WATEK
WET PROCESS
STORAGE
BASIN
ilk
CUNKER
GYPSUM
-1
1
(
r-
i
"i
i i
?
CAR
PRODUCT
STORAGE
TO
THICK,
•OX CA*
PACKAGING
MACHINE
CM
Figure 4-53. Sources of particulate emissions in cement plant.
-------
I
LO
o
CO
Figure 4-54. A typical rotary cement kiln and clinker cooling system with fabric filter
(Courtesy of Wheelabrator-Frye, Philadelphia, PA.)
-------
B. Dryers and Grinders: Raw materials are initially fed
into grinders and dryers prior to calcining in the kiln.
Ball or rod mills are used to grind the materials to a fine
size. Exhaust gas flow rates are about 780 m /Mg of feed
(25,000 scf/ton) and exit temperatures are about 93°C
(200°F). After calcining, clinker cooling, and the
addition of gypsum, finish grinding is usually performed in
a compartment mill close-circuited with an air circulator.
Following the grinding, the finished product is ready for
2
packaging.
4.9.1.2 Emissions - Particulate emission factors for the
dry process are 123 g/kg (245 Ib/ton) for the kiln and
cooler system and 48 g/kg (96 Ib/ton) for the dryers and
grinders. At 450 ppm lead, the total plant lead emission
factor is estimated at 0.08 g/kg (0.15 Ib Pb/ton) cement
produced. At a production rate of 35.8 Tg (3.95 x 10
tons) and an overall control efficiency of 93 percent, the
total lead emissions from the dry process in 1975 are
estimated at 188 Mg (207 tons).
For the wet process, the particulate emission factors
are 114 g/kg (228 Ib/ton) for the kiln and cooler system and
4
16 g/kg (32 Ib/ton) for the dryers and grinders. At 450
ppm lead, the total plant lead emission factor is estimated
at 0.6 g/kg (0.12 Ib Pb/ton) of cement produced. At a
production rate of 29.5 Tg (3.25 x 107 tons) and an overall
4-309
-------
control efficiency of 93 percent, the total lead emissions
from the wet process in 1975 are calculated to be 124 Mg
(137 tons).
The above estimates compare favorably with the data
given in reference 8, stating that the national particulate
emissions from the dry and wet processes were 381 Gg (420,000
tons) and 292 Gg (322,000 tons), respectively, corresponding
to totals of 172 Mg (190 tons) and 132 Mg (145 tons) of lead
emissions, respectively.
Table 4-53 presents characteristics of exhaust gas from
a kiln and cooler system. Sources of fugitive dust are
screens, storage bins, packaging facilities, transfer
points, elevator boots, and loading stations. These are
minor sources of lead and particulate emissions and are
usually controlled by fabric filters or by application of
water or chemicals to suppress dust.
4.9.1.3 Control Techniques - Particulate matter is the
primary air pollutant from the manufacture of Portland
cement. The cement industry uses mechanical collectors,
electrostatic precipitators, gravel beds, and fabric filters,
or combinations thereof, depending upon the operation and
exhaust gas temperatures. Although high-energy wet col-
lectors (venturi scrubbers) are used in some plants, they
are not generally used in the Portland cement industry.
4-310
-------
Table 4-53.
CHARACTERISTICS OF UNCONTROLLED EXHAUST GAS
FROM PORTLAND CEMENT KILN
Parameters
Gas flow rate
Temperature
Moisture
content
a
Grain loading
Particle size
distribution
Lead content
of particulate
Emission
factors^3
0 particulate
0 lead
Standard
international
units
26 m3/s-Gg-da"1
200-315°C
5% vol. (dry
process)
30% vol. (wet
process)
12-50 g/m3
58% < 20 ym
38% < 10 ym
23% < 5 ym
3% < 1 ym
450 ppm by
weight
120 g/kg
dry process
114 g/kg
wet process
0.06 g/kg
dry process
0.05 g/kg
wet process
English
units
50 acfm/tpd
product
400-600°F
5% vol. (dry
process)
30% vol. (wet
process)
5-20 gr/scf
58% < 20 ym
38% < 10 ym
23% < 5 ym
3% < 1 ym
450 ppm by
weight
240 Ib/ton
dry process
228 Ib/ton
wet process
0.11 Ib/ton
dry process
0.10 Ib/ton
wet process
References
2
5
6
7
4
4
Lower range for wet process exhaust and higher range for
dry process exhaust.
Expressed in terms of production rate.
4-311
-------
A. Fabric Filters; Fabric filters installed on cement
kilns, grinders, coolers, and transfer points can achieve
efficiencies of 99.5 percent or higher. Also effective are
reverse-air cleaning with a filtration velocity of 0„6 to
Oo8 cra/s {1.2 to 1..5 fpm) , pulse-jet cleaning with a filtra-
tion velocity of 3.5 to 5 cm/s (7 to 10 fpm), or mechanical
shaker cleaning with a filtration velocity of 1 to 1.5 cm/s
9 R
(2 to 3 fpm), Fiberglass or Nomex bags, at temperatures
of 230 to 290°C (450-550°F), can be utilized. Average bag
life is about 2 years. Pressure drops of 0.8 to 1.7 kPa (3
to 7 in- H.?0) are common. Grain loadings as low as 92 to 34
£a
rag/m (0.04 and 0.015 gr/scf) can be achieved on dry and wet
process kilns, respectively.
Condensation of moisture in -che filter compartment will
cause bag plugging, increased pressure drop, bag wear, and
reduced collection efficiency. Duct work can be insulated
2
to prevent condensation. Baghouses have provided more
reliable operation than precipitators, although precipitators
require less energy and operate at lower costs.
The relative small particle size of clinker cooler dust
requires the use of high-energy control devices to meet new
source performance standards. Although precipitators are
not widely used for clinker cooler control, several installa-
tions are operating successfully.
4-312
-------
Screens, mills, storage bins, and packaging facilities
are usually vented to mechanical collectors and baghouses in
series. Transfer points, drop points, elevator boots, and
loading stations should be hooded to control emissions.
These are relatively minor sources of lead emissions.2
Raw and finish milling processes are usually controlled
by fabric filters, although precipitators effectively clean
the exhaust streams from finish mills. These control
devices, connected in a closed loop with air separators,
transport the collected material back to the process for
2
cement production.
B. Electrostatic Precipitators; In wet-process plants,
the performance of ESP's is greatly enhanced by the addi-
tional moisture content of the exhaust gases. For efficient
performance in dry process plants, the exhaust gases must be
conditioned by water sprays to decrease particle resistivity
2
and temperature. Drift velocities of 7.6 to 13.7 cm/s
9
(0.25 to 0.45 fps) are typical. Efficiencies of 99 percent
or greater can be attained.
When precipitators or fabric filters are used on wet-
process kilns, extensive thermal insulation must be provided
to prevent condensation of water vapor within the device.
Although some precipitators are specified to withstand a
maximum temperature of 370°C (700°F), the usual operating
2
range is 150 to 260°C (300 to 500°F). Wet-process kiln
4-313
-------
gases exhibit the proper moisture and temperature charac-
teristics for effective electrostatic precipitation. Several
preheater installations utilize the kiln exhaust gases to
dry and heat the raw material, increasing the moisture
2
content of the gas and reducing its temperature.
4.9.2 Metallic Lead Products
Lead is consumed and emitted in the manufacture of
ammunition, bearing metals, weights and ballasts, caulking
lead, pipes and sheet lead, and other products. Over 180 Gg
of lead (200,000 tons) was consumed by these industries in
1975.12 A total of 77 Mg of lead emissions (85 tons)
resulted from these manufacturing operations.
4.9.2,1 Process Descriptions
A. Ammunition: Lead used in the manufacture of ammunition
is processed by melting and alloying before it is cast,
sheared, extruded, swaged, or mechanically worked in the
production of lead shot or lead-filled ammunition. Some
lead is also reacted to form lead azide, a detonating
agent. Little or no pollution control equipment is used.
B. Bearing Metal: Lead is used in bearing manufacture by
alloying it with copper, bronze, antimony, and tin to form
various alloys or babbitts having desirable properties of
lubrication, strength, and temperature. The bearings are
used in electric motors, machines, and engines.
4-314
-------
C. Other Sources of Lead; Other lead products include
terne metal, weights and ballasts, caulking lead, plumbing
supplies, roofing materials, casting metal foil, collapsible
tubes, and sheet lead. Lead is also used for galvanizing,
annealing, and plating. The lead is usually processed by
melting and casting followed by mechanical forming opera-
tions. These small manufacturers do not use air pollution
control equipment.
4.9.2.2 Emissions
A. Ammunition; Emission factors are estimated at 0.5 g/Mg
(1.0 lb/10 ton) of lead processed or less. The usage of
lead in 1975 for ammunition production was 68.1 Gg (75,081
12
tons), and lead emissions were only 34 kg (75 Ib).
B. Bearing Metal; Although lead is melted, alloyed,
machined, mechanically formed, cleaned and handled, the
emissions from this source are negligible, even without
pollution control. Only 10.96 Gg of lead (12,184 tons)
12
was used by this source in 1975.
C. Other Sources of Lead; The lead emission factors are
reported to range from 0.3 to 2.2 g/kg (0.5 to 4.3 Ib/ton)
of lead processed, averaging 0.8 g/kg (1.5 Ib/ton) of lead
processed. The following amounts of lead were processed
in 1975: caulking lead, 13.0 Gg (14,296 tons); pipe and
sheet lead, 35.5 Gg (39,092 tons); weights and ballast, 18.2
Gg (20,018 tons); and other, 36.4 Gg (40,097 tons), for a
4-315
-------
12
total of 102.9 Gg (113,503 tons). With an emission factor
of 0.75 g/kg (1.5 Ib/ton), 1975 emissions from these sources
were about 77 Mg (85 tons).
4.9.2.3 Control Techniques - Published information is very
scarce regarding the process description, emission charac-
teristics, control techniques, and control costs for manufac-
ture of metallic lead products. The available references
12
state that little or no emission control is provided.
4„9.3 Lead Glass Production
In 1975, total glass production was about 14.9 Tg (16.4
1^ _
million tons) . ' j.t is assumed that the production of lead
glass accounted for about 3 percent of the glass produced,
totalling 446 Gg (492,000 tons). Lead emissions to the
atmosphere from this industry were 56 Mg (62 tons) in 1975.
4.9.3.1 Process Description - Lead glass is basically
composed of silica sand and lead oxide. The lead oxide
content usually ranges from 12 and 60 percent, although some
types contain as much as 92 percent lead oxide. Lead
oxide glass has a high refractive index and density, high
electrical resistivity, and a low softening temperature.
Because of these properties it is useful for radiation
shielding, fluorescent lamp envelopes, optical glasses, and
lead crystal glass.
4-316
-------
Glass manufacturing techniques vary widely; common
procedures include batch weighing, mixing, charging, and
melting operations. Batch weighing and mixing systems range
from manual to fully automated operations. Most plants use
rotating-barrel type mixers, which tumble the batch upon
itself in a revolving drum or double cone. The glass
furnaces are charged continuously or intermittently by means
of manual or automatic feeders.
Most glass is melted in conventional end or side-port
regenerative or recuperative furnaces. Natural gas or oil
is the fuel, with or without electric "boosting". A typical
regenerative furnace is shown in Figure 4-55.
In the furnace, the mixture of materials is held in a
molten state at about 1540°C (2800°F) until it acquires the
homogenous character of glass. It is then cooled gradually
in other sections of the furnace to about I200°C (2200°F) to
make it viscous enough to form. The glass is drawn from the
furnace and worked on forming machines by a variety of
methods including pressing, blowing in molds, drawing,
rolling, and casting. Handling of raw materials and the
furnace and forming operations are potentially significant
sources of atmospheric emissions. The glass furnace is
usually the major source.
4-317
-------
CLASS SURFACE IN DEFINE!)
IUSS SURFACE IN BELTER
NATURAL DRAFT STACK
BACK HALL
COMBUSTION AIR BLOWER *"\ DUCI
IOVABLE «EF»ACTO»» BAFFLE
lUKNEII
RIDER ARCHES
Figure 4-55. Regenerative glass furnace.
16
4-318
-------
4-9-3.2 Emissions - The composition and rate of emissions
from glass melting furnaces varies considerably, depending
on the composition of glass being produced and, to a lesser
extent, on the design and operating characteristics of the
furnace.
Operators of one lead glass furnace report tests
showing that particulate emissions range from 12 to 19 g/kg
(24 to 38 Ib/ton) of charge in producing glass containing 28
percent lead. The lead emission factors are 2.6 to 4.0 g/kg
(5.1 to 8.0 Ib/ton) of glass produced, based on a 23 percent
lead content of the particulate and an 8 percent throughput
loss due to volatilization. The average of three tests were
17
2.5 g Pb/kg (5.0 Ib/ton) glass. Gas flow rates were
measured at 1.0 m /s • Mg • h~ throughput (3300 acfm/tph).
Outlet gas temperature ranged from 400 to 425°C (750 to
800°F). Outlet grain loading ranged from 2.2 to 3.2 g/kg
(0.9 to 1.3 gr/scf).17
Based on an estimated lead glass production rate of 446
Gg (492,000 tons), the 1975 annual lead emissions were about
56 Mg (62 tons), assuming an overall control efficiency of
95 percent.
4.9.3.3 Control Techniques -
A. Raw Material Handling; Practices such as choke feed-
ing, enclosed unloading, and use of "socks" between trans-
port car discharge and conveyor pickup points can reduce
fugitive dust emissions.
4-319
-------
Vent filters can be used to control emissions from bin
filling and conveying operations. Fabric filters can be
used to control emissions from mixers and weigh hoppers.
Particulate collection efficiency of such units exceeds 99
percent on a weight basis.
B. Glass Furnace: When emissions slightly exceed regula-
tions, the least expensive and most desirable control
methods involve modification of operating variables. These
methods include (1) use of raw materials with lower content
of fines; (2) maintainence of free moisture of the batch at
about 4 to 5 percent; (3) control of the air-fuel ratio; (4)
use of electrical energy to supplement and reduce the use of
other fuels; e_nd (5) reduction of air flow rate on the
18
furnace, ' Emissions can be further reduced by lowering
furnace temperatures by such means as reducing the airflow
rate, increasing cr.llet (broken glass) ratios, modifying
batch preparation, and by increasing the amount of electri-
cal boosting.
If these techniques are inadequate for meeting emission
limits, a baghouse provides the most effective means of
controlling particulate emissions. Collection efficiencies
have exceeded 99 percent on certain types of glass furnaces.
In pilot study the filtering velocity was 2 to 2.5 cm/s (4
to 5 fpm) with a pressure drop of 2 to 2.5 kPa (8 to 10 in.
H20). Full-scale units are operating with filtering
4-320
-------
velocities ot 0.5 to I cm/s (1 to 2 fpm) . Precautions must
be taken to overcome problems of acid gases and high tempera-
tures, since SO,, and SO_ in the effluent will cause severe
acid corrosion and hot off-gases cause deterioration of the
filter cloth. Bags made of felted Nomex , silicons-treated
P
glass fiber, and Dacron have been used effectively in these
applications. '
Wet scrubbers have proved relatively ineffective in
collecting the particulates of submicron size characteristic
of glass furnace emissions. Tests of a low-pressure-drop,
wet centrifugal scrubber showed an overall efficiency of
18
only 52 percent. Higher-energy venturi scrubbers require
a pressure drop of over 13 kPa (50 in. H_0) to achieve an
efficiency of approximately 97 percent.
Electrostatic precipitators have also proved ineffec-
tive. Tests on certain glass furnaces Indicate efficiencies
between 80 and 90 percent. One ESP on a lead glass
furnace achieved 97 percent efficiency.
4-321
-------
4.9.4 References for Section 4.9
1. U.S. Industrial Outlook 1976. U.S. Department of
Commerce. Domestic and International Business Adminis-
tration. Bureau of Domestic Commerce. January 1976.
465 p.
2. Emissions, Effluents, and Control Practices for Sta-
tionary Particulate Pollution Sources. Chapter 10.
Midwest Research Institute. Kansas City, Mo. For
National Air Pollution Control Association, Cincinnati,
OH. Contract No. CPA 22-67-104. November 1, 1970.
607 pp.
3. Kulujian, N. J. Inspection Manual for the Enforcement
of New Source Performance Standards: Portland Cement
Plants. PEDCo Environmental Specialists, Inc. Cincin-
nati, OH. For U.S. Environmental Protection Agency,
Washington, D.C. Contract No. 68-02-1355, Task 4.
January 1975.
4. Compilation of Air Pollutant Emission Factors. 2nd
Edition. U.S. Environmental Protection Agency.
Research Triangle Park, N.C. Publication AP-42.
Februarv, 1976.
5. Control Techniques for Particulate Air Pollutants.
U.S. Environmental Protection Agency. Research Triangle
Park, N.C. Publication AP-51. January 1969. 215 pp.
6. Kreichelt, T. E., et. al. Atmospheric Emissions from
the Manufacture of Portland Cement. Publication
999-AP-17. U.S. DHEW. PHS. N CAPC. Cincinnati, Ohio.
1967-
7. EPA Test No. 71-MM-02, 71-MM-02, 71-MM-03 and 71-MM-05.
Emission Measurements Bra.nch. U.S. Environmental
Protection Agency. Research Triangle Park, N.C.
8. National Emission Data Systems. Environmental Protec-
tion Agency. Research Triangle Park, N.C. March 1976.
9. Kinkley, M.L. and R.B. Neveril. Capital and Operating
Costs of Selected Air Pollution Control Systems. Draft
report. Card, Inc. Niles, Illinois. For U.S. Environ-
mental Protection Agency. Research Triangle Park, N.C.
Contract No. 68-02-2072. Mar-jh 1976.
4-322
-------
10. Pesachowitz, A.M. Portland Cement Plants. Division of
Stationary Source Performance. Environmental Protection
Agency- Washington, D.C. 30 pp.
11. Hardison, L. C. and H. R. Herrington. Study of Techni-
cal and Cost Information for Gas Cleaning Equipment in
the Lime and Secondary Non-ferrous Metallurgical
Industries. Industrial Gas Cleaning Institute. Rye,
N.Y. For U.S. Environmental Protection Agency- Research
Triangle Park, N.C. Contract EPA 70-150. December 31,
1970. 293 p.
12. Lead Industry in May 1976. Mineral Industry Surveys.
U.S. Department of Interior. Bureau of Mines. Washing-
ton, D.C. August 5, 1976.
13. Emission Study of Industrial Sources of Lead and Air
Pollutants. 1970. U.S. Environmental Protection
Agency. APTD-1543. By W.E. Davis. Contract No.
68-02-0271. May 1973.
14. Private Communication. July 23, 1976.
15. Dietz, E. D. Glass. In: Chemical and Process Tech-
nology Encyclopedia. Considine, D.M. Los Angeles,
McGraw-Hill, Inc. 1974. p. 552-561.
16. Danielson, J. A. Air Pollution Engineering Manual.
U.S. Department of Health, Education, and Welfare.
Cincinnati, Ohio. 1967. No. 999-AP-40. p. 776.
17. Confidential Test Data. PEDCo-Environmental Specialist,
Inc. Cincinnati, Ohio.
18. Simon, H. and J. E. Williamson. Control of Fine Parti-
culate From Continuous Melting Regenerative Container
Glass Furnaces. (Presented at Annual Air Pollution
Control Association Meeting, Boston, June 15-20, 1975).
12 p.
19. Kline, H. L. Discussion Outline: Air Pollution Control
in the Glass Industry- In: Environmental Sciences
Part III "Air Pollution Control in the Ceramics Industry.
American Institute of Chemical Engineers. August 28,
1972. p. 1-6.
20. Franz, C. N. et.al. Glass Furnace Particulate Emission
Control Equipment. (Presented at 32nd Annual Conference
on Glass Problems. Urbana-Champaign. November 11,
1971) .
4-323
-------
APPENDIX
SYSTEMS OF UNITS1
The International System of units (SI) used in this
document are expressed in or derived from the following
basic quantities:
Quantity
length
mass
time
temperature
Unit
metric
gram
second
Celsius
Symbol
m
g
s
°C
Derived units such as m/s or g/m can be obtained
directly from a combination of the conversion factors given
in Table A-l and A-2. Other derived quantities are given
below with their respective unit, symbol, and formula:
Quantity
frequency
force
pressure
energy
power
Unit
hertz
newton
pascal
joule
watt
Symbol
Hz
N
Pa
J
W
Formula
s-1
kg- m/s
N/m2
N-m
J/s
SI units are formed by a combination of the basic units
above and the prefixes in Table A-l.
A-l
-------
Table A-l. PREFIXES FOR THE SI SYSTEM OF MEASUREMENT
Multiplication factor
1 000 000 000 000
1 000 000 000
1 000 000
1 000
1
0.
0.000
0.000 000
0.000 000 000
0.000 000 000 000
000 000 =
000 000 =
000 000 =
000 000 =
000 000 =
1 000 =
100 =
10 =
0.1 =
0.01 =
0.001 =
000 001 =
000 001 =
000 001 =
000 001 =
000 001 =
IO18
io15
io12
io9
io6
io3
io2
io1
10"1
io"2
io-3
io-6
io-9
io-12
io-15
io-18
Prefix
exa
peta
tera
giga
mega
kilo
hecto
dekab
deci
centi
milli
micro
nano
pico
femto
atto
Symbol
E
P
T
G
M
k
h
da
d
c
m
P
n
P
f
a
All data given in this document are expressed in the
new SI system of units and are followed by the equivalent
expressed in common English units. The following are
examples of this format:
5 kPa
3
(20 in. H2O)
4.6 g/m (2 gr/scf)
10 m3/s (21,190 acfm)
Units such as microgram per cubic metre (yg/m3) and
micrometre (ym) are almost exclusively used as common
English units in current literature and legal documents.
A-2
-------
Therefore these units are used to express ambient air con-
centration and particle size and no equivalent English units
are given.
Mixed units such as grains per mile (g/mi) and grams per
gallon (g/gal) are also exclusively used in current litera-
ture and legal documents pertaining to automotive emission
control. These units have been expressed in the SI system
followed by the common units as in the following example:
10 g/km (16.1 g/mi)
18.9 g/1 (5 g/gal)
Table A-2 presents factors to convert SI system of
units into English units.
A-3
-------
Table A-2. CONVERSION FACTORS'
Multiply
By
To obtain
Energy
Length
Mass
Pressure
Temperature
joule (J)
meter (m)
gram (g)
kilogram (kg)
pascal (Pa)
pascal (Pa)
degrees cen-
tigrade (°C)
Velocity
Volume
centimeters/second
(cm/s)
meters/second
(m/s)
liter (1)
cubic metre
(m3)
9.478 E-04
3.281 E+00
2.205 E-03
1.102 E-03
1.450 E-04
4.019 E-03
1.8 (T°C)+32
1.969 E+00
2.237 E+00
2.642 E-01
2.642 E+02
British Thermal
Unit (BTU)
foot (ft)
pound (Ib)
ton (short)
pound/sq. in.
(psi)
inch of water
(60°F)
degrees Fahren-
heit (°F)
feet/minute (fpm)
miles per hour
(mph)
gallon (gal)
gallon (gal)
The usage of SI units in this document conforms to the
standard and international guidelines in Standard for
Metric Practice. American Society for Testing and Materials,
Philadelphia, Pa. ASTM Publication E 380-76, 268-1975.
January 19, 1976. 37p.
A-4
-------
APPENDIX B
The purpose of this section is to outline the details
and assumptions of the control cost analyses performed for
the following industries:
Lead Additives Production
Battery Manufacturing
Primary Lead Smelting
Primary Zinc Smelting
Primary Copper Smelting
Secondary Lead Smelting
Brass and Bronze Production
Gray Iron Foundries
Lead Oxide Manufacturing
Ferroalloys Production
Municipal Incineration
Table B-l shows the steps necessary in order to arrive
at the total equipment cost. Tables B-2 and B-3 present the
bases for determining capital and annualized costs from the
total equipment cost.
Higher capital costs are generally required for the
installation of control equipment in existing plants than
for new plants. A control system can be incorporated into
the overall design of a proposed plant, whereas a retrofit
application requires that the system be adapted to the rigid
configurations of the existing plant. Additional labor and
material expenses are incurred for longer duct runs, tight
B-l
-------
Table B-l. STEPS TO DETERMINE TOTAL EQUIPMENT COSTS
W
I
NJ
Choose a model size
process
Determine exhaust gas
characteristics
3. Select a typical emission
control system
4„ Determine control system
design parameters
5. Size required equipment
6. Price required equipment
Material throughput,
production, annual
operating hours.
Volume, temperature, grain
loading, mass emission
rate, moisture.
Type of control device, gas
cooling and conditioning,
ductwork, materials of
construction.
Total system efficiency,
pressure drop, air-to-cloth ratio,
ESP plate area, etc.
Hold tank volume, baghouse
cloth area, fan horsepower,
ductwork weight.
Based on vendor and manu-
facturer's quotations.
-------
Table B-2. CAPITAL COST BASES
DIRECT COSTS
Material and Labor Components
Equipment
Instrumentation
Piping
Electrical
Foundations
B* Installation Factors3
Shell-and-tube heat exchanger
Pump systems
U-tube coolers
Fan systems
Ductwork
Fabric filter
ESP
Venturi scrubber
Packed tower
Hold tank
Quench tower
Vacuum filter
INDIRECT COSTS
Interest during construction
Field labor and expenses
Contractor's fee
Engineering
Freight
Offsite
Spares
Taxes
Shakedown
CONTINGENCIES
Structure
Sitework
Insulation
Painting
3.5
4.0
3.5
2.5
2.6
2.0
2.0
3.0
3.0
2.0
3.0
3.0
of total direct costs
10
10
5
10
1.25
3.0
0.5
1.5
5.0
20% of directs
and indirects
Multiply by base equipment price to include material and
labor components (A) for direct costs for field erection.
Installation factors are obtained from Chemical Engineering
(1969), Perry's Handbook, PEDCo Environmental.
B-3
-------
Table B-3. ANNUALIZED COST BASES
A. Utilities
Electricity
Water
B. Operating Labor
Direct
Supervision
C. Maintenance
$0.03/kWh
$0.25/M gal.
0.3-2 men/shift; $10/man-hr
15% direct
Labor and materials
Supplies
Overhead
Plant
Payroll
Fixed Costs
Capital recovery
Taxes, insurance,
etc.
Q
Sludge Disposal
5% TCI - fabric filter
2% TCI - ESP
4% TCI - venturi Scrubber
15% labor and materials
50%(B
20% B
C)
11.75% TCI for ESP and fabric
filter
16.28% TCI for venturi scrubber
4% TCI
$22 per trip (70-minute round-trip)
10 tons per trip
$40 per load for landfill charge
Dependent on system size and characteristics.
TCI = Total capital investment.
Based on 20 year equipment life; 10% interest.
Based on 10 year equipment life; 10% interest.
Conversation with Mr. Richard Toftner of PEDCo Environmental
Inc., Cincinnati, Ohio.
B-4
-------
spaces, and delayed construction. Other capital cost
components that can be increased are construction labor,
and expenses, interest during construction, contractor fees,
and allowance for shakedown.
Table B-4 indicates the retrofit factors assumed in the
cost studies for each industry. With two exceptions (see footnote),
these factors are multiplied by the total direct costs to account
for the additional costs.
Table B-4. RETROFIT FACTORS
Lead additives
Batteries
Primary lead
Primary copper
Primary zinc
Iron and steel
Brass and bronze
Ferroalloys
Gray iron
Lead oxide
Secondary lead
Municipal incineration
1.2
1.2
1.4
1.4
1.4
1.4
1.2
1.3
1.2
1.1
1.2
1.1
a
a
The costs given in the document for the above indus-
tries reflect particulate control costs for achieving an
average state emission limitation for existing plants.
These costs should be within + 30 percent of the true value,
based on volume flow rate.
Cost equations can be developed relating exhaust flow
rate to capital costs. The most accurate method of de-
termining a capital cost equation is to evaluate three or more
system sizes. Plotting capital cost versus exhaust flow
rate on log-log graph paper usually yields a straight line from
aFor this industry, multiply retrofit factor by total new plant
installed cost, to obtain retrofit installed cost.
B-5
-------
which an equation can be derived. The equation will be of
the form:
Capital cost, $ = CQ ,
where Q is exhaust volume at a specific temperature, and C
and a are constants. The equation would predict capital
cost within a certain range of flow rates.
Annualized costs can be expressed as an equation
relating cost to exhaust flow rate and annual labor hours.
Annualized costs include components which are directly
related to flow rate (utilities), capital costs (mainte-
nance, overhead, and fixed costs) and labor hours (labor and
overhead) . The cost equation, therefore, is of the fol-
lowing form:
Annualized cost, $ = AQ + BQa + CH,
where a, A, B, and C are constants, Q is exhaust flow rate
at a specific temperature, and H is annual labor hours. Costs
related to solid waste disposal and credit for product recovery
can also be included in the equation.
Most cost equations given in this document were derived
from only one middle-sized control system. The "Q to the point
six law" (Q ' ) is used to determine the capital cost equation.
Most equipment size-cost exponents are between 0.5 to 0.7.
To reduce the error it is recommended that the equations be
used for volume flow rates of a factor of about 3 on either
side of the volume for the model plant. This allows the use
a
See Section 2.9 and Appendix B for discussion of cost analyses
Detailed cost studies are available from EPA upon request.
-------
4 5
of the equation within a factor of about 10, i.e. 10 to 10 ,
An example cost analysis for a brass and bronze re-
verberatory furnace, equipped with a fabric filter emission
control system, is presented below.
Attachment I is a process description and cost summary.
Table B-5 indicates the typical exhaust gas characteristics.
Figure B-l shows a sketch of the control system and design
parameters. Table B-6 is a detailed schedule of required
equipment, design and cost bases, bare costs, installed
costs, and total capital costs. Table B-7 shows the break-
down of the annualized costs.
B-7
-------
ATTACHMENT I
Control Costs - A reverberatory furnace rated at a
production capacity of 45.3 Mg/day (50 TPD) is considered
the typical model size to determine control costs. The fur-
nace exhausts 18.4 m3/s at 1090°C (39,000 acfm at 2000°F)
and emits 83 kg/h (183 Ib/hr) particulate matter, of which
15 percent is lead. The gases enter a quench tower, where
they are cooled to 120°C (250°F) before they enter a fabric
filter. The fabric filter must be insulated to prevent
condensation. The shaker-type fabric filter is designed to
handle 8.5 m /s (18,000 acfm) at a superficial filter velocity
3
of 1.2 cm/s (2.5 fpm). A fan system rated at 8.5 m /s
(18,000 acfm) and a system pressure drop of 1.8 kPa (7 in.
W.G.) is also required. This control technique will permit
compliance with the average state particulate limitation of
3.6 kg/h (7.9 Ib/hr), with an overall efficiency of more
than 99 percent. This corresponds to an actual emission
rate of 0.83 kg/h (1.83 Ib/hr) particulate and 0.12 kg/h
(0.27 Ib/hr) lead.
Capital costs are estimated at $407,000, including
quench tcwer, pump, hold tank, collector, insulation, fan
system, and ductwork.
Annualized costs are estimated at $202,000, including
utilities, labor, maintenance, overhead, fixed costs (with
capital recovery), and solid waste disposal in sealed bar-
rels. An annual operating time of 6000 hours and annual
-------
labor of 2000 hours are assumed.
Capital and annualized costs are expressed below in
terms of exhaust flow rate, annual labor hours, and furnace
capacity:
S.I, units
Capital, $ = 7.1 x 104V°'6
Annualized, $ = 587V + 1030 M + 19.6H + 2.1 x 105V°'6
V = m3/s at 1090°C
H = annual labor hours
M = furnace capacity, Mg/day product
Range: 6 < V < 60
range
English units
Capital, $ = 716 Q°*6
Annualized, $ = 0.277Q + 932T + 19.6H + 187Q0'6
Q = acfm at 2000°F
H = annual labor hours
T = furnace capacity, TPD product
(for solid waste disposal costs)
Range: 13,000 < Q < 130,000
range
B-9
-------
Table B-5. CHARACTERISTICS OF UNCONTROLLED EXHAUST
GAS FROM A BRASS AND BRONZE REVERBERATORY FURNACE
Parameters
Gas flow ratea
Temperature
Grain loading
Particle size
distribution
Lead content
of particulate
Emission factors
0 Particulate
0 Lead6
Standard
International
units
4.5 mVs'Mg-h"1
product
925-1315°C
0.12-9.4 g/m3
0.03-0.5 ym
(majority)
High-leaded 58% w
yellow and red 15%
Other brass and
bronze 7% w
35 g/kg
charge
2. 4 g/kg charge
English
units
8600 acfm/tph
product
1700-2400°F
0.05-4.1 gr/scf
0.03-0.5 ym
(majority)
70 Ib/ton
charge
4.9 Ib/ton chc
References
3
16
13
15
15
15
13,17,18
14
arge
b
Flow rates can vary according to the hooding arrangement
required. Volume given is at 120°C (250°F).
Temperature is usually reduced to 120°C (250°F).
Dependent upon lead content of the product.
See Section 4.4 for references.
Based on 7% w Pb in particulate.
B-10
-------
labor of 2000 hours are assumed.
Capital and annualized costs are expressed below in
terms of exhaust flow rate, annual labor hours, and furnace
capacity:
S.I, units
Capital, $ = 7.1 x 104V°'6
Annualized, $ = 587V + 1030 M + 19.6H + 2.1 x 105V°'6
V = m3/s at 1090°C
H = annual labor hours
M = furnace capacity, Mg/day product
Range: 6 < V < 60
range
English units
Capital, $ = 716 Q°*6
Annualized, $ = 0.277Q + 932T + 19.6H + 187Q0'6
Q = acfm at 2000°F
H = annual labor hours
T = furnace capacity, TPD product
(for solid waste disposal costs)
Range: 13,000 < Q < 130,000
range
B-9
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Table B-5. CHARACTERISTICS OF UNCONTROLLED EXHAUST
GAS FROM A BRASS AND BRONZE REVERBERATORY FURNACE
Parameters
Gas flow rate
Temperature
Grain loading
Particle size
distribution
Lead content
of particulate
Emission factors
0 Particulate
° Lead6
Standard
International
units
4.5 mVs-Mg-h"1
product
925-1315°C
0.12-9.4 g/m3
0.03-0.5 ym
(majority)
High-leaded 58% w
yellow and red 15%
Other brass and
bronze 7% w
35 g/kg
charge
2. 4 g/kg charge
English
units
8600 acfm/tph
product
1700-2400°F
0.05-4.1 gr/scf
0.03-0.5 urn
(majority)
70 Ib/ton
charge
4.9 Ib/ton ch<
1 : _ __ J
References
3
16
13
15
15
15
13,17,18
14
arge
Flow rates can vary according to the hooding arrangement
required. Volume given is at 120°C (250°F).
Temperature is usually reduced to 120°C (250°F).
Dependent upon lead content of the product.
See Section 4.4 for references.
Based on 7% w Pb in particulate.
B-10
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PUMP
O-*
30> LINED 300 GPM '
39,000 ACFM / ' X \
n 2000°F QUENCH
TOWER "o cm
t-l\j brrl
30 GPM
KLVtKBtKArURY nHNL-Ur ^
FURNACE
300
HOLD
FAN
f \ *~
*"\ ^
1 20' 20' Z±±l 20'
/ ^
/ s
18,000 ACFM / ^INSULATION
^ 250°F / 1
/ /
^^^^ -r*^
^^"X^^ ^^f^^
SHAKER-TYPE
FABRIC-FILTER DISposAL
GAL.
TANK
Figure B-l. Control system diagram for brass and bronze
reverberatory furnaces.
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Table B-6. DETERMINATION OF CAPITAL COSTS FOR PARTICULATE CONTROL
SYSTEM FOR A BRASS AND BRONZE REVERBERATORY FURNACE
Equipment iten
Quench tower*
Pump
Fabric filter*1
Pan system
Ductwork
Insulation for baghouse
Hold tank
Da.ign bag is
R^fractorylined-1/4* carbon
to 250°F
Centrifugal 300 gpra
100 ft. head
A/c = 2.5. Shaker-type
Dacronb baga
18,000 acfm
System iP - 7" WG
18,000 acfm
1/4" carbon steel -
3500 fpm velocity
3" thick mineral wool with
aluminum casing
10 nin. retention carbon
construction
Capacity/tile
39,000 acfm in.
15 hp
7,500 ft2 cloth
area
35b hp
90 feet total
2900 ft2 area
300 gal.
Coet source and ba.ls
Croll-Reynolda-refractory
brick is $50/ft3 installed
Inger soil-Rand
$92/hp includes base.
motor, couples
Fisher Klostermann
$3/ft2 cloth
$75/hp - PEDCo estimate
includes motor, starter.
drive
S1.5/lb carbon steel
installed directs
Means Cost Data
57.5/ft2 installed
Kramig Co., Cincinnati
Chem. Eng.
1969
Bare coat.
30,000
1,300
22,500
2,600
14,000
inst.
21,800
inst.
6,900
Installation
factor
3.0
4.0
2.0
2.5
1.5
Direct cost
A. Total adjusted direct cost
(direct cost x retrofit factor
1.2)
B. Total indirect cost (46» of A)
C. Contingency (20% of A + B)
0, Total capital cost (A + B + C)
Direct installed
Cost, f
90,000
5,200
45,000
6, 500
14, 000
21,000
10, 400
193,000
232,000
107,000
68,000
407,000
CO
I
ro
Includes vessel, spray heads, controls, and supports.
Includes bags, shaker unite, ladder, supports, hoppers, and factory assembly.
Includes motor, drive, and starter.
Does not include exnanqi^n joints, elbows, transitions-, etc. Contingency
and retrofit costs will cover these items.
-------
Table B-7. CONTROL SYSTEM ANNUAL OPERATING COST
Raw Material
Electricity
Water
Sludge disposal
Labor
Operating labor
Supervision
Maintenance
Labor and material
Supplies
Overhead
Plant
Payroll
Fixed costs
0 Ton/hr.
45 kW 30 mills/kWh
30 gpm SO- 25/M gal.
540 tpy
2000 hr
6 man-hr/day $10/man~hr
15% of operating labor
6% of total capital cost
including bag replacement
15% of labor and materials
50% of labor and maintenance
20% of labor
15.75% of total capital cost
Total annual cost, $
Cost, $
0
8,100
2,700
46,600
20,000
3,000
24,400
3,600
25,500
4,600
64,000
202,000
11 kW pump + 26 kW fan power + 20% miscellaneous for lighting,
conveyors, etc.
Includes barrels, shipment, labor, and disposal charge at
landfill.
B 13
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-450/2-77-012
13. RECIPIENT'S ACCESSIOf^NO.
4. TITLE AND SUBTITLE
Control Techniques for Lead Air Emissions
6. PERFORMING ORGANIZATION CODE
. AUTHOR(S)
. /-\i_i i n w n \o J
David M. Augenstein, Tom Corwin, Robert Hearn, Vishnu
Katari, James Sperber, and Robert L, Harris, Jr.
8 PERFORMING ORGANIZATION REPORT NO.
5. REPORT DATE
January 1973
9. PERFORMING ORGANIZATION NAME AND ADDRESS
PEDCo Environmental, Inc.
Chester Towers
Cincinnati, Ohio 45246
10. PROGRAM ELEMENT NO.
11 CONTRACT/GRANT NO.
Contract No. 68-02-1375
Task No. 32
12. SPONSORING AGENCY NAME AND ADpRESS
U.S. Environmental Protection Agency
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
200/04
15. SUPPLEMENTARY NOTES
PEDCo Project Director: Richard W. Gerstle
EPA Project Officers: John R. Floyd and George B. Crane
16. ABSTRACT
This publication describes sources of atmospheric lead (Pb) emissions in the United
States and deals with methods of emission control and estimated costs of controls.
Lead emissions have been almost ubiquitous in this country and have arisen from
automobiles, the metallurgical industry, fuel combustion, and many lead-using manu-
facturing processes. Gasoline combustion contributed 90.4 percent of the 141.4 Gg
(155,900 tons) total lead emissions in 1975. The next largest lead emitters were
waste oil disposal, primary copper smelting, and solid waste incineration. Significant
sources of fugitive lead emissions are primary nonferrous smelters and secondary lead
smelters. Lead emissions from gasoline have consisted mostly of lead halides and
oxyhalides. Industrial lead emissions consist mainly of lead oxides; lead alkyl manu-
facture emits small amounts of those alkyls as vapors. Control of lead emissions from
automobiles is being achieved by reduction or elimination of lead in gasoline. Partic-
ulate lead emissions from industry are being controlled by electrostatic precipitators
and fabric filters, up to efficiencies of about 99.5 and 99.9 percent, respectively.
Scrubber efficiencies can reach 99 percent at the expense of high power usage. Cost
data on lead emission controls is limited; therefore, for most industrial sources,
model plants were described, and equations were derived for capital and annualized
costs, based on exhaust flow rate and annual labor hours. Appendix B of the document
shows how the equations may be adjusted to apply to either new or retrofit constructio
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Lead emissions
Fugitive emissions
Gasoline combustion
Nonferrous smelters
Control techniques
Costs
3. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
554
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
C-l
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