EFA-453/R-93-040
September 1993
LOCATING AND ESTIMATING AIR EMISSIONS
FROM SOURCES OF CADMIUM AND
CADMIUM COMPOUNDS
By
Ms. Robin Jones
Dr. Tom Lapp
Dr. Dennis Wallce
Midwest Research Instiitute
Gary, North Carolina
Contract Number 68-D2-0159
EPA Project Officer: Anne A. Pope
U. S. ENVlRONMEaMTAL PROTECTION AGENCY
Office Of Air and Radiation
Offic8 Of Air Quality Planning And Standards
Research Triangle Park, North Carolina 27711
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This report has been reviewed by the Office of Air Quality Planning
and Standards, U. S. Environmental Protection Agency, and has been
approved for publication. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
EPA 454/R-93-040
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TABLE OF CONTENTS
Section
EXECUTIVE . SUMMARY
1 PURPOSE OF DOCUMENT
2 OVERVIEW OF DOCUMENT CONTENTS . . ...
3 BACKGROUND
3.1 NATURE OF POLLUTANT ..'.....
3.2 OVERVIEW OF PRODUCTION, USE,' AND EMISSIONS
3.2.1 Production . . . . .
3.2.2 Use '.'.]'.
3.2.3 Emissions . . . . .
4 EMISSIONS FROM CADMIUM PRODUCTION
4.1 CADMIUM REFINING AND CADMIUM OXIDE
PRODUCTION
4.1.1 Process Description ] ] '.
4.1.2 Emissions and Controls . . .
4.2 CADMIUM PIGMENTS PRODUCTION
4.2.1 Process Description ........
4.2.2 Emissions and Controls ...
4.3 CADMIUM STABILIZERS PRODUCTION '.
4.3.1 Process Description ........
4.3.2 Emission and Controls ..-...""
4.4 OTHER CADMIUM COMPOUND PRODUCTION . . . .
4.4.1 Process Descriptions .......
4.4.2 Emissions and Controls ..'.'.'.'.
5 EMISSIONS FROM MAJOR USES OF CADMIUM
5.1 CADMIUM ELECTROPLATING ..........
5.1.1 Process Description .......
5.1.2 Emission Control
5.1.3 Emissions
5.2 SECONDARY BATTERY MANUFACTURE ......
5.2.1 Process Description ........
5.2.2 Emission Control Measures .
5.2.3 Emissions
5.3 CADMIUM STABILIZERS FOR PLASTICS '.
5.3.1 Process Description ] ]
5.3.2 Emission Control Measures ....."
5.3.3 Emissions .•.
5.4 .. CADMIUM PIGMENTS IN PLASTICS '.'.'.....
5.4.1 Process Description ........
5.4'.2 Emission Control Measures ...'..
5.4.3 Emissions .... ° " ••* —
Page
xiii
1-1
2-1
3-1
3-1
3-4
3-4
3-6
3-6
4-1
4-1
4-3
4-6
4-11
4-14
4-18
4-21
4-21
4-22
4-24
4-26
4-28
5-1
5-1
5-2
5-6
5-6
5-7
5-8
5-12
5-13
5-14
5-16
5-17 .
5-17
5-18
5-21
5-21
5-22
iii
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TABLE OF CONTENTS (continued)
Section
6 EMISSIONS.FROM COMBUSTION SOURCES ....
• 6.1 COAL COMBUSTION ....
6.1.1 Coal Characteristics ....
6.1.2 Process Description . . .-• .
6.1.3 Emission Control Measures . .
6.1.4 Emissions '.'...
6.2 FUEL- OIL COMBUSTION
6.2.1 Fuel Oil Characteristics . !
6.2.2 Process Description ..... .
6.2.3 Emission Control Measures . .
6.2.4 Emissions
6.3 NATURAL GAS COMBUSTION . .
6.3.1 Natural Gas Characteristics .
6.3.2- Process Description
6.3.3 Emission Control Measures . .
6.3.4 Emissions
6.4 WOOD COMBUSTION
6.4.1 Process Description
6.4.2 Emission Control Measures . .
6.4.3 Emissions
6.5 MUNICIPAL WASTE COMBUSTION .....'
6.5.1 Municipal Solid Waste
Characteristics ........
.6.5.2 Process Description
. 6.5.3 Emission Control Measures . .
6.5.4 Emissions
6.6 SEWAGE SLUDGE INCINERATORS ..-.!!
6.6.1 Process Description
6.6.2 Emission Control Measures . .
6.6.3 Emissions
6.7 MEDICAL WASTE INCINERATION . . . . .
6.7.1 Process Description ,
6.7.2 Emission Control Measures . .
6.7.3 Emissions
7 EMISSIONS FROM NONFERROUS SMELTING/REFINING
7.1 PRIMARY LEAD SMELTING
7.1.1 Process Description ....!!
7.1.2 Emission Control Measures . .* '.
7.1.3 Emissions
7.2 PRIMARY COPPER SMELTING ....!.*!
7.2.1 .Process Description ....!!
7.2.2 Emission Control Measures .
7.2.3 Emissions ..... 0
Page
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6-5
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6-12
6-15
6-17
6-23
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6-2.9
6-30
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6-71
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7-5 .
7-7
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7-14
iv
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TABLE OF CONTENTS (continued)
Section « \
7.3 . PRIMARY ZINC SMELTING AND REFINING
7.3.1 Process Description - Electrolytic
7.3.2 Process Description--
Pyroraetallurgical (Electrothermic)
7.3.3 Emission Control Measures . •.
7.3.4 Emissions.. ........
7.4 SECONDARY COPPER SMELTING AND REFINING ! '.
7.4.1 Process Description ........
7.4.2 Emission Control Measures . . ." ]
• 7.4.3 Emissions '. .
7.5 SECONDARY ZINC RECOVERY FROM METALLIC*
SCRAP
7.5.1 Process Description ........
7.5.2 Emission Control Measures .....'
7.5.3 Emissions
7.6 SECONDARY ZINC RECOVERY FROM STEEL
PRODUCTION . •
7.6.1 Process Description '. . .
7.6.2 Emission Control Measures . . ] ] '.
7.6.3 Emissions ]
8 EMISSIONS FROM MISCELLANEOUS SOURCES
8.1 IRON AND STEEL PRODUCTION ......
8.1.1 Process Description ........
8.1.2 Emission Control Measures
8.1.3 Emissions .
8.2 PORTLAND' CEMENT MANUFACTURING
8.2.1 Process Description ]
8.2.2 Emission Control Measures . . . . .
8.2.3 Emissions
8.3 PHOSPHATE ROCK PROCESSING ....'.'.'.'.
8.3.1 Process Description
8.3.2 Emission Control Measures ...'.'.
8.3.3 Emissions
8.4 CARBON BLACK PRODUCTION .........
8.4.1 Process Description '.'.'.
8.4.2 Emission Control Measures . . . . .
8.4.3 Emissions
8.5 MOBILE SOURCES ....
Page
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TABLE OF CONTENTS (continued)
S_ection
SOURCE TEST PROCEDURES
9.1 INTRODUCTION
9.2 MULTIPLE METALS SAMPLING TRAINS " . . . .
9.2.1 Method 0012-Methodology for the
Determination of Metals Emissions
in Exhaust Gases from Hazardous
Waste Incineration and Similar
Combustion Sources ........
9.2.2 Methodology for the Determination of
Metals Emissions in Exhaust Gases
from Hazardous Waste Incineration-
and Similar Combustion Sources . .
9.2.3 CARS Method 436-Determination of
Multiple Metals Emissions from
Stationary Sources
9.2.4 EPA Method 29-Methodology for the
Determination of Metals Emissions
in Exhaust Gases from Incineration
and Similar Combustion Sources
(Draft)
9.3 ANALYTICAL METHODS FOR DETERMINATION OF*
CADMIUM
9.4 SUMMARY ........
10 REFERENCES '
APPENDIX A - NATIONWIDE EMISSION ESTIMATES
APPENDIX B - SUMMARY _OF COMBUSTION SOURCE CADMIUM
EMISSION DATA ...
APPENDIX C - PLANT LOCATIONS AND ANNUAL CAPACITIES FOR
MISCELLANEOUS EMISSIONS SOURCES .
Paae
9-1
9-1
9-2
9-2
9-4
9-4
9-4
9-5
9-7
10-1
A-l
B-l
C-l
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LIST OF FIGURES
3-1 1991 supply and demand for cadmium ........ 3-5
3-- 2 End use pattern of cadmium ......... 3_7
4-1 Flow diagram for cadmium refining . ........ 4-4
4-2 . Process flowsheet for the production "of cadmium
pigments .................. ..... 4_16
4-3 General flowsheet, for the production of powdered
cadmium stabilizers ....'....- ...... 4-23
5-1 Cadmium electroplating process .......... 5.3
5-2 Simplified flow, diagram for production of
sintered plate nickel -cadmium batteries ...... 5-10
,6-1 Distribution of sewage sludge incinerators in
tile U-S ..... - ........................ 6-56
6-2 Process flow diagram for sludge incineration ... 6-57
6-3 Major components of a medical waste incineration
system . . . . . ............. _ ..... 6.66
7-1 Typical primary lead-processing scheme ...... 7.3
7-2 Typical primary copper -smelt ing process .'..... 7-9
7-3 Typical primary zinc-smelting process ....... 7-19
7-4 Process flow diagram for second-grade copper
recovery ....... . ....... ...... 7-29
7-5 Process flow diagram for high-grade brass and
bronze alloying ... .............. 7_30
7-6 Process flow diagram for secondary zinc
processing ................... _ 7_37
7-7 Process flow diagram for Waelz kiln process .... 7-45
7-8 Process flow diagram' for zinc : calcine formation'. . 7-43
Vii
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LIST OF FIGURES (continued)
Figure
8-1 General flow diagram for the iron and steel
industry
8-2 Process flow diagram of portland cement
manufacturing process
9-1 Typical multiple metals sampling train
8-3 Typical flowsheet for processing phosphate rock
8-4 Process flow diagram for carbon black
manufacturing process
8-5
8-16
8-24
8-29
9-3
viii
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LIST OF TABLES
page
ES-1 ESTIMATED NATIONWIDE EMISSIONS .......... .. xiv
3-1 PHYSICAL PROPERTIES OF CADMIUM ..... , ..... 3-2
3-2 SIC CODES OF INDUSTRIES ASSOCIATED WITH CADMIUM
• EMISSIONS . .- ................... 3-1-0
3-3 ESTIMATED 1990 NATIONWIDE CADMIUM EMISSIONS FOR
. SELECTED SOURCE CATEGORIES . ....... .... 3-12
4 - 1 CADMIUM AND CADMIUM OXIDE PRODUCERS ......... 4-2
4-2 INVENTORY OF CADMIUM EMISSION SOURCES AND
CONTROLS FOR CADMIUM REFINING PLANTS ....... 4-7
4-3 PRIMARY ZINC AND CADMIUM PRODUCERS REPORTING
CADMIUM EMISSIONS IN THE 1990 TOXIC CHEMICALS
RELEASE INVENTORY ......... . ..... 4_1G
4-4 CADMIUM EMISSION FACTORS FOR CADMIUM REFINING
PLANT USING LEAD BLAST FURNACE DUST . ....... 4-12
4-5 EMISSION FACTORS FOR CADMIUM AND CADMIUM OXIDE
PRODUCTION .................... 4_13
4-6 COMMON CADMIUM PIGMENTS PRODUCED IN 1991 ..... 4-15
4-7 CURRENT CADMIUM PIGMENT PRODUCERS ........ . 4-15
4-8 INORGANIC PIGMENTS MANUFACTURERS REPORTING
CADMIUM EMISSIONS IN THE 1990 TOXIC CHEMICALS
RELEASE INVENTORY .... ..... ........ 4.20
4-9 MANUFACTURERS OF ORGANIC COMPOUNDS REPORTING
CADMIUM EMISSIONS IN THE 1990 TOXIC CHEMICALS
RELEASE INVENTORY ........... . ..... 4.25
4-10 OTHER CADMIUM COMPOUNDS AND THEIR USES ...... 4-26
4-11 CADMIUM COMPOUND MANUFACTURERS (OTHER THAN
CADMIUM OXIDE, PIGMENTS, AND STABILIZERS) ..... 4-29
4 - 12 MANUFACTURERS OF INORGANIC COMPOUNDS REPORTING
CADMIUM AIR EMISSIONS IN THE 1990 TOXIC CHEMICALS
RELEASE INVENTORY ..... - 4 30
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LIST OF TABLES (continued)
5-1 MARKET AREAS FOR CADMIUM COATINGS ......... 5.2
.5-2 COMPOSITION AND OPERATING PARAMETERS OF CADMIUM
CYANIDE PLATING BATH ... ' - • -' - c
•••••«••.... 3 - 5
5-3 NICKEL -CADMIUM BATTERY PRODUCERS- -1990 ...... ; 5.9
5-4 REPORTED CADMIUM EMISSIONS BY ' MANUFACTURERS OF
FORMULATED RESINS AND PLASTIC PRODUCTS ...... 3 -19
5-5 REPORTED CADMIUM EMISSIONS BY PRODUCERS OF
CUSTOM COMPOUNDED RESINS ............. 5.20
6-1 DISTRIBUTION OF FOSSIL FUEL CONSUMPTION IN THE
UNITED STATES ..... e -•
*••••• ..... , o-j
6-2 COAL HEATING VALUES . . . ~ -
••••••...... b - /
6-3 EXAMPLES OF COAL HEAT CONTENT VARIABILITY, ..... 6-9
6-4 CADMIUM CONCENTRATION IN COAL BY COAL TYPE .... 6-11
6-5 CADMIUM CONCENTRATION IN COAL BY REGION ....".. 6-11
6-6 CALCULATED UNCONTROLLED CADMIUM EMISSION FACTORS
FOR COAL COMBUSTION .... e i a
*.•••«•••«... o- iy
6-7 MEASURED CADMIUM EMISSION FACTORS FOR COAL
COMBUSTION ..... - on
•••••: ...... .. b-^U
6-8 BEST 'TYPICAL CADMIUM EMISSION FACTORS FOR COAL
COMBUSTION .... ,- ._
................ 6-22
6-9 TYPICAL HEATING VALUES OF FUEL OILS ..-....-.. 6-26
6-10 TYPICAL FUEL OIL HEATING VALUES FOR SPECIFIC
REGIONS ...................... 6-27
6-11 CADMIUM CONCENTRATION IN OIL BY OIL TYPE ..... 6-28
6-12 CALCULATED UNCONTROLLED CADMIUM EMISSION FACTORS
FOR FUEL OIL COMBUSTION ........... . . . 6-32
6-13 MEASURED CADMIUM EMISSION FACTORS FOR FUEL OIL
COMBUSTION ...... WJ"4..
« ' • e » • o . .•„•"••.- .' • • O - J J
6-14 CADMIUM EMISSION FACTORS FOR FUEL OIL COMBUSTION
GENERATION FROM CALIFORNIA ' " HOT "SPOTS " TESTS . . . " 6-34
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LIST OF TABLES (continued)
Table
6-15 BEST- TYPICAL CADMIUM EMISSION FACTORS FOR FUEL
OIL COMBUSTION ....
6-16 SUMMARY OF CADMIUM EMISSION FACTORS FOR WOOD
COMBUSTION .... •
6-17 SUMMARY OF GEOGRAPHICAL DISTRIBUTION OF MWC
FACILITIES
6-18 CURRENT AND FORECAST COMPOSITION OF DISPOSED
RESIDENTIAL AND COMMERCIAL WASTE (WEIGHT
PERCENT)
6-19 BEST TYPICAL CADMIUM EMISSION FACTORS FOR
MUNICIPAL WASTE COMBUSTORS
6-20 SUMMARY OF CADMIUM EMISSION FACTORS FOR SEWAGE
SLUDGE INCINERATORS ...
6-21 SUMMARY OF UNCONTROLLED CADMIUM EMISSION FACTORS
FOR MEDICAL WASTE INCINERATORS
6-22 SUMMARY OF CONTROLLED CADMIUM EMISSION FACTORS
AND CONTROL EFFICIENCIES FOR MEDICAL WASTE
INCINERATORS . . . ^^ ™^J.a
6-23 BEST TYPICAL UNCONTROLLED CADMIUM EMISSION
FACTORS FOR MEDICAL WASTE INCINERATORS
7-1 DOMESTIC PRIMARY LEAD SMELTERS AND REFINERIES
PRIMARY LEAD PRODUCERS REPORTING CADMIUM EMISSIONS
7-2
7-3
IN THE 1990 TOXICS RELEASE INVENTORY
CADMIUM EMISSION FACTORS FOR LEAD - SMELTING
FACILITIES ....
7-4 DOMESTIC PRIMARY COPPER SMELTERS AND
REFINERIES ...
7-5
PRIMARY COPPER PRODUCERS REPORTING CADMIUM
EMISSIONS IN THE 1990 TOXICS RELEASE INVENTORY
7-6 CADMIUM EMISSIONS FROM PRIMARY COPPER
PRODUCTION ......
DOMESTIC PRIMARY... ZINC PRODUCERS^.
Page
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6-42
6-44
6-45
6-54
S-63.
6-73
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6-76
7-2
7-5
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7-7
7-14
7-16
7-18
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LIST OF TABLES (continued)
Table
7-8 PRIMARY ZINC PRODUCERS REPORTING CADMIUM
EMISSIONS IN THE 1990 TOXICS RELEASE
INVENTORY
7-9 CADMIUM EMISSIONS FROM PRIMARY ZINC
PRODUCTION.
7-10 DOMESTIC SECONDARY COPPER PRODUCERS
7-11 SECONDARY COPPER PRODUCERS REPORTING CADMIUM
EMISSIONS IN THE 1989 AND 1990 TOXICS RELEASE
INVENTORY .......
7-12 DOMESTIC PRODUCERS OF SECONDARY ZINC FROM
METALLIC SCRAP
7-13 CADMIUM EMISSIONS FROM SECONDARY ZINC RECOVERY
FROM METAL SCRAP
7-14 DOMESTIC PRODUCERS OF SECONDARY ZINC FROM EAF
DUST
8-1 INTEGRATED IRON AND STEEL PLANTS
8-2 COKE PRODUCTION CAPACITY FOR INTEGRATED IRON
AND STEEL FACILITIES IN THE UNITED STATES IN
1991
8-3 CADMIUM RELEASES REPORTED BY IRON AMD STEEL
FACILITIES IN 1990 TRI ....
8-4 CADMIUM EMISSIONS REPORTED FROM BETHLEHEM STEEL
SPARROWS POINT, MARYLAND
8-5 CARBON BLACK PRODUCTION FACILITIES
9-1 CADMIUM SAMPLING METHODS
Page
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7-26
.7-27
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.7-36
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8-6
8-13
8-14
8-28
9-8
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EXECUTIVE SUMMARY
The.-emissions of cadmium and cadmium.compounds into the '
atmosphere are of special significance because of the Clean Air
Act Amendments of 1990. These amendments include cadmium and its
compounds in'the Title III list of hazardous air pollutants and
mandate that cadmium emissions be subject to standards
established under Section 112, including maximum achievable
control technology. This document is designed to assist groups
interested in inventorying air emissions of cadmium by providing
a compilation of available information on sources and emissions
of these substances. •
In the U.S., cadmium is-produced primarily as a byproduct
of smelting domestic and imported zinc concentrates; there are
three major producing companies. In 1991, the total U.S. supply
of cadmium was 4,368 Mg (4,805 tons), of which 53 percent
resulted from U.S. primary and secondary processes and producer
stockpiles and 47 percent resulted from imports. In 1991, the
U.S. demand was 3,238 Mg (3,562 tons) or 74 percent of the
supply. This demand represents a slight increase over the 1990
demand level of 3,107 Mg (3,418 tons) but was less than the 1989
demand level of 4,096 Mg (4,506 tons).
In 1991, five source categories accounted for the U.S.
demand for cadmium; battery production, at 45 percent, was the
major user. Other major uses of cadmium were coating and plating
operations, pigment production, and plastic and synthetic
products. These three source categories accounted for 48 percent
of the total U.S. demand for cadmium. The smallest end-use
xiii
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category was alloys-and other uses, which accounted for
7 percent.
Nationwide cadmium emissions were estimated for several
source categories for 1990. This was the latest year for which
adequate information was available for all source categories and
it was not desirable to mix the specific source emission
estimate* for 1990 and 1991. The total 1990 nationwide cadmium
emissions estimate was 307 Mg (339 tons) from five major source
categories. Table ES-1 shows the estimated nationwide emissions
by major source category and the percent contribution of each
category to the total emissions. The five specific sources
emitting the largest quantities of cadmium were coal combustion,
oil combustion, primary lead smelting, municipal waste
combustion, and, sewage sludge combustion.
TABLE ES-1. ESTIMATED NATIONWIDE EMISSIONS
Major source category
Cadmium Production
Major Uses of Cadmium
Combustion Sources
Nonferrous Smelting and
Refining
Miscellaneous Sources
TOTAL
Estimated nationwide
emissions, Mg (tons)
9.1 (10.1)
3.3 (3.6)
2S8.9 (285.3)
31.5(34.8)
4.5 (4.9)
307 (339)
Percent of total emissions
2.9
1.1
84.3
10.2
1.5
100
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SECTION 1
PURPOSE OF DOCUMENT
The U. S. Environmental Protection Agency (EPA) ," state-, and
local air pollution control agencies are becoming increasingly
aware of the presence of substances in the ambient air that may
be toxic at certain concentrations. This awareness, in turn, has
led to attempts to identify source/receptor relationships for
these substances and to develop control programs to regulate '
emissions. Unfortunately, little information exists on the
ambient air concentration of these substances or about the
sources that may be discharging them to.the atmosphere.
To assist groups interested in inventorying air emissions of
various potentially toxic substances, EPA is preparing -a series
of documents such as this that compiles available information on
sources and emissions of these substances. Prior documents in
the series are listed below:
Substance
Acrylonitrile
Carbon Tetrachloride
Chloroform
Ethylene Bichloride
Formaldehyde •
Nickel
Chromium
Manganese
Phosgene
Ep i chlorohydrin
Vinylidene Chloride
Ethylene Oxide
Publication
EPA-450/4-
EPA-450/4-
EPA-450/4-
EPA-450/4-
EPA-450/4-
EPA- 450/4-
EPA-450/4-
EPA-450/4-
EPA-450/4-
EPA-450/4-
EPA-450/4-
EPA-450/4-
84-007a
84-007b
84-007C
84-007d
91-012
84-007f
84-007g
S4-007h
84-007i
84-007J
84-007k
84-0071
1-1
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Chlorobenzene
Polychlorinated Biphenyls (PCB's)
Polycyclic Organic Matter (POM)
Benzene .
Perchloroethylene and
Trichloroethylene
Municipal Waste Combustion
Coal and Oil Combustion
1,3-Butadiene
Chromium (Supplement)
Sewage Sludge
Styrene
Mercury
Methylene Chloride
Medical Waste
TCDD/TCDF
Toluene
Xylenes
Methyl Ethyl Ketone
Methyl Chloroform
Chlorobenzene (Update)
Chloroform (Update)
BPA-4SO/4-84-007m
EPA-450/4-84-007n
EPA-450/4-84-007p
EPA-450/4-84-007q
EPA-450/2-89-013
EPA-450/2
EPA-450/2
EPA-450/2
EPA-450/2
EPA-450/2
EPA-454/R
EPA-454/R
EPA-454/R
Number to
Number to
Number to
Number to
Number to
Number to
Number to
Number to
'-89-006
-89-001
-89-021
-89-002
-90--009
-93-011
-93-023
-93-006
be Assigned
be Assigned
be Assigned
be Assigned
be Assigned
be Assigned
be Assigned
be Assigned
This document deals specifically with cadmium and cadmium
compounds; however, the majority of the information contained in
this document concerns cadmium. Sources of cadmium emissions
evaluated in this document include: (1) cadmium production and
use processes; (2) emissions from combustion sources;
(3) production of other nonferrous metals where cadmium emissions
result as inadvertent byproducts of the process; (4) production
processes for selected materials other than nonferrous metals;
and (5) mobile sources. Data presented in this document are
total -cadmium emissions and do not differentiate the metallic and
ionic forms.of cadmium.
In addition to the information presented in this document,
another potential source of emissions data for cadmium and
cadmium compounds is the Toxic Chemical Release Inventory (TRI)
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form required by Section 313 of Title III of the 1986 Superfund
Amendments and Reauthorization Act (SARA 313) .1 SARA 313
requires owners and operators of facilities in certain Standard
Industrial Classification Codes that manufacture, import, process
or otherwise use toxic chemicals (as listed in Section 313) to
report annually their releases of these chemicals to all
environmental media. As part of SARA 313, EPA provides public . :
•access to the annual emissions data. The TRI data include
general facility information, chemical information, and-emissions
data". Air emissions data are reported as total facility release
estimates for fugitive emissions and point source emissions. No
individual process or stack data are provided to EPA under the
program. The TRI requires sources to use stack monitoring data
for reporting, if available, but the rule does not require stack
monitoring or other measurement of emissions if it is
unavailable. ' If monitoring data are unavailable, emissions are •
to be quantified based on best estimates of releases to the
environment.
The reader is cautioned that the TRI will not likely provide
facility, emissions, and chemical release data, sufficient for
conducting detailed exposure modeling and risk assessment. In
many cases, the TRI data are based on annual estimates of
emissions (i.e., on emission factors, material balance
calculations, and engineering judgment). We recommend the use of
TRI data in conjunction with the information provided in this
document to locate potential emitters of cadmium and to make
preliminary estimates of air emissions from these facilities.
Cadmium is of particular importance as a result of the Clean
Air Act. Amendments of 199,0. Cadmium and its .compounds are
included in the Title III list of hazardous air pollutants and
will be subject to standards established under Section 112,
(MACT) . These
1-3
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standards are to be promulgated no later than 10 years following
the date of enactment.
1-4
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SECTION 2
OVERVIEW OF DOCUMENT CONTENTS
As noted in Section 1, the purpose of this document is to
assist Federal, State, and local air pollution agencies and
others who are interested in locating potential air emitters of
cadmium and cadmium compounds and estimating air emissions from
these sources. Because of the limited background data available,
the information summarized in this'document does not and should
not be assumed to represent the source configuration or emissions
associated with any particular facility.
This section provides an overview of the contents of this
document. It briefly outlines the nature, extent, and format of
the material presented in the remaining sections of this
document.
Section 3 of this document provides a brief summary of the
physical and chemical characteristics of cadmium and cadmium
compounds and an overview of their production and uses. A
chemical use,tree summarizes the quantities of cadmium produced
as well as the relative amounts consumed by various end uses.
This background section may be useful to someone who wants to
develop a general perspective on the nature of the substance and
where it is manufactured and consumed.
Sections 4 to 7 of this document focus on the major '
industrial source categories that may discharge cadmium-
containing air emissions. Section 4 discusses the production of
.^.Section 5, dlscuMseg.._the_.di_£f^rLent._
2-1
-------
major uses of cadmium as an industrial feedstock. Section 6
discusses emissions from combustion sources. Section 7 discusses
emissions from selected nonferrous smelting/refining processes,
and Section 8 discusses emissions from miscellaneous production
processes and mobile sources. For each major industrial source
category described, process descriptions and flow diagrams are
given wherever possible,., potential emission points are
identified, and available emission factor estimates are presented
that show the potential for cadmium emissions before and after
controls are employed by industry. Individual companies are
identified that are reported to be involved with the. production
and/or use of cadmium based on industry contacts, the Toxic
Release Inventory (TRI), and available tra.de publications.
Section 9 of this document summarizes available procedures
for source sampling and analysis of cadmium and Section 10
provides the references. Details are not. prescribed nor is any
EPA endorsement given or implied for any of these sampling and
analysis procedures. .Appendix A presents calculations used to
derive the estimated 1990 nationwide cadmium emissions.
Appendix B presents a summary of the combustion source test data.
Appendix C lists names and locations of electric arc furnaces,
U.S. portland cement manufacturers, phosphate rock processors,
and elemental phosphorus producers.
This document does not contain any discussion of health or
other environmental effects of cadmium, nor does it include any
discussion of ambient air levels or ambient: air monitoring
techniques.
Comments on the content or usefulness of this document are
welcome, as'is any information on process descriptions, operating
2-2
-------
practices, control measures, and emissions that would enable EPA
to improve its contents. All comments should be sent to:
Chief, Emission Factor and Methodology Section (MD-14)
Emission Inventory Branch
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
2-3
-------
-------
SECTION 3
BACKGROUND
This section discusses cadmium and its compounds and alloys,
their chemical and physical properties, and their commercial
uses. The section also provides statistics on cadmium production
and use. Finally, the section presents nationwide estimates of
cadmium emissions from the sources discussed in the other
sections of this document.
3 .1 NATURE OF POLLUTANT
Cadmium is a soft, ductile, silvery-white metal. It was
discovered by Stromeyer in 1817 as an impurity in zinc carbonate.
Table 3-1 summarizes cadmium's chemical and physical properties.
When heated in air, cadmium forms a fume of brown-colored
cadmium oxide, CdO. Other elements which react readily with
cadmium metal upon heating include the halogens, phosphorus,
selenium, and tellurium. The metal is not attacked by aqueous
solutions of alkali hydroxides.
Cadmium is slowly attacked by warm dilute hydrochloric or
sulfuric acid with the evolution of hydrogen but is rapidly
oxidized to the cadmium ion by hot dilute nitric acid with
evolution of various oxides of nitrogen (NOX). Cadmium is
displaced from solution by more electropositive metals such as
zinc or aluminum. The hydroxide of cadmium, Cd(OH)2/ is
virtually insoluble in alkaline media. -The cadmium ion forms
3-1
-------
TABLE 3-1. PHYSICAL PROPERTIES OF CADMIUM
Property
Value
Atomic weight
Crystal structure
CAS registry number
Atomic number
Valence
112.41
Hexagonal
7440-43-9
48
2
Outer electron configuration
Metallic radius, A
Covalent radium, A
Electrode potential, normal, V
2e'
4d1°5s2
1.54
1.48
-0.4013
Melting point, °C
Boiling, point, °C
Latent heat of fusion, J/g (cal/g)a
Latent heat of vaporization, J/g (cal/g)a
Specific heat, J/mol«K (cal/mol»K)a
Solid, 20°C
Liquid, 321 ° to 700 °C .
321.1
767
55.2 (13.2)
886.9 (212)
25.9 (6.19)
29.7. (7.10)
Electrical resistivity,
at 22°C
at.400°C
at 600 °C
at 700°C
Density, kg/m3.
at 26°C
at melting point
at 400 °C
at 600 °C
7.27
34.1
34.8
35.8
8,624
8,020
7,930
7,720
Thermal conductivity, W (m«K), at 0°C
Vapor pressure, mmHg
at 382°C
at 478 °C
at595°C
at 767°C
98
0.7598
7.598
75.98
759.8
Source: Reference 2.
aTo convert J to cal, divide by 4.184.
3-2
-------
stable complexes with ammonia, as well as cyanide and halide
ions.
Elemental cadmium is used primarily as an electroplated,
corrosion resistant coating applied to iron, steel, brass,
.copper, and aluminum. Cadmium coatings are especially useful for
protecting surfaces expos.ed to corrosive marine environments. An
added advantage of using cadmium surface coatings is that cadmium
is preferentially attacked by the corrosive environment and
protects the base metal from corrosion. Even if the cadmium
coating is slightly damaged, it continues to provide protection
to the base metal.
Elemental cadmium coatings also have a low coefficient of
friction, good electrical conductivity, are easily soldered, and-
have low volume corrosion products. The coatings reduce galvanic
corrosion between steel and other metals, particularly aluminum.
Technically and commercial-ly important cadmium compounds
include the oxide, sulfide, selenide, chloride, sulfate, nitrate,
hydroxide, and various organic cadmium salts of fatty acids, such
as the palmitate and stearate. The only naturally occurring
compound is the sulfide, CdS (greenockite), which is an accessory
mineral in sulfide ores of lead, zinc, and copper and in sulfur-
bearing coals.2'^
Cadmium forms alloys with many metals; these alloys fall
into two major groups: those in which cadmium helps reduce the
melting point and those in which cadmium improves mechanical
properties.2»4,5
3-3
-------
3.2 OVERVIEW OF PRODUCTION, USE, AND EMISSIONS
This subsection summarizes cadmium production statistics-,
identifies industrial categories using cadmium, and provides '
estimates of nationwide cadmium emissions.-
3-2.1 Production
Primary production of cadmium occurs as a byproduct of
smelting domestic and imported zinc concentrates. There are
three major producing companies in the u.S,, and all produce the
cadmium from smelting zinc concentrates.
Figure-3-1 presents the 1991 supply-and-demand diagram for
cadmium. The information in this figure was obtained from the -
U.S. Bureau of Mines, Division of Mineral Commodities.6 As shown
in Figure 3-1, the total U.S. supply of cadmium was 4,368 Mg
(4,805 tons). An estimated 38 percent of the total supply
resulted from U.S. primary and secondary production processes,
and 47 percent was the result of imports. The remaining
IS percent came from producer stockpiles. Figure 3-1 also shows
that of the total 1991 U.S. cadmium supply, 74 percent was used
to meet domestic demands, while 4 percent met export demands, and
22 percent supplied industry stocks. Exports of cadmium are in
the form of cadmium metal and cadmium in alloys, dross, flue
dust, residues, and scrap.6
The Bureau of Mines reported U.S. production of 329 Mg
(362 tons) of cadmium sulfide (including lithopone and cadmium
sulfoselenide) and 1,089 Mg (i,i98 tons) of plating salts,
•cadmium oxide, and other compounds. The remaining 1,820 Mg
..(2,002 tons) of U.S. demand in 1991 apparently-was-comprised of •
cadmium metal, alloys, and imported compounds.6 The 1991 demand
of 3,238 Mg (3,562 tons) shown in Figure 3-1 represents a slight
3-4
-------
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3-5
-------
increase over the 1990 demand level of 3,107 Mg (3,418 tons, , but
less than the 1989 demand levels of 4,096 Mg (4,506 tons).
3.2.2 Use
The Bureau of Mines estimates that U.S. consumption of
fivTarlast ^^ COnPOUndS °CCUrS' P^^^ in the following
1.
2.
3.
4.
5.
Battery production;
Coatings and platings;
Pigments;
Plastic and synthetic products (primarily as
stabilizers); and
Alloys and other products.
The estimated percentage of the total 1991 U.S. cadmium
supply that was consumed by each end-use category is shown in .
BattSry Pr°dUCtion' at 4S P-rc«nt, accounts for the
PTTagS °f CadniiUm COnSU«*tio« <1*«7 Mg/^603 tons).
and plat.ng operations were the next largest consumer at
.2° PSrCent (648 ^/713 tons). The third and fourth largest
consumer categories were pig^nts at 16 percent (518 Mg/570 tons)
and plastxc and synthetic products (presumed to be primarily
' " ^ " PerCent"(3" Mg/428 «=«»)- ™* smallest end-
3-2.3 Bmissipna
. Two distinct methods were used to develop nationwide
em.ss.on estimates for specific source categories. The first.
method involved developing source-specific emission factors and
applyxng those emission, factors ..tc^symwes ,.of nationwide, source
3-6
-------
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activity to calculate nationwide cadmium emission estimates. The
second method relied on extrapolating emission estimates from the
Toxic Chemicals Release Inventory System (TRI).7
Cadmium is emitted from a number of industrial processes
(e.g., fossil fuel combustion, waste incineration, and mineral
processing operations) because it is present as a contaminant- in
the process feed. For those processes, an emission factor-based
approach was used to estimate nationwide cadmium emissions. A
comprehensive review and analysis of both information on cadmium
content in the feed material and emission test data was
conducted. Primary sources of information, which were used
included ongoing EPA regulatory development activities,
information that is being collected by EPA to develop toxic air
pollutant emission factors in AP-428, and an EPA data base on
toxic air pollutant emission factors.9 Upon completion of the
review, a "best typical" emission factor was selected. This
information was combined with readily available published data on
source category activity to calculate nationwide emission
estimates.
The source of emissions information used for source
categories that involve cadmium use was the TRI form, required by
Section 313 of Title III of the 1986 Superfund Amendments and
Reauthorization Act (SARA 313).7 This section requires owners
and operators of facilities in Standard Industrial Classification
(SIC) codes 20-39 that manufacture, import, process, or otherwise
use toxic chemicals to report annual air releases of these
chemicals. The emissions may be based on source tests (if
available); otherwise, emissions may be based on emission
factors, mass balances, or other approaches.
In selected cases, facilities reported to TRI under multiple
SIC codes. As a result, it was difficult to assign emissions to
3-8
-------
a specific SIC code. In those cases, efforts were made to
determine the appropriate SIC codes associated with the
emissions. If appropriate SIC codes could not be explicitly
identified, the data were not used in the analysis.
Table 3-2 presents a compilation of SIC codes that have been
associated with cadmium emissions.8'9 This table lis'fcs the SIC
codes that were identified as a potential source of cadmium
emissions, provides a description of the SIC code, and identifies
other emission sources that do not have an assigned SIC code.8'9
Table 3-3 provides a summary of the estimated 1990
nationwide cadmium emissions for those source categories where
adequate information was available (i.e., emission factors and
production data) . Appendix A presents the data used for each of -.
these estimates, assumptions, and emission calculations for each
of these source categories. The estimated emissions were based
on emission factors provided in this document or calculated from
source test data and appropriate process information, if
available.
Of the five major source categories, cadmium emissions
resulting from combustion sources accounted for a total of 259 Mg
(285 tons) or approximately 84 percent of the total estimated
emissions of 307 Mg (339 tons). Within the combustion source
category, the major contributor to cadmium emissions was from the
combustion of coal, followed by oil combustion, municipal waste,
and sewage sludge. The nonferrous smelting and refining source
category accounts for about 32 Mg (35 tons) or approximately
10 percent of the total estimated emissions.
3-9
-------
TABLE 3-2. SIC CODES OF INDUSTRIES ASSOCIATED WITH CADMIUM EMISSIONS
SIC code I Industry
0711
266
2611
2621
2816
2819
2851
2869
2874
2879
2895
2911
2951
3053
3081
Soil Preparation Services (fertilizer application)
Woven Fabric Finishing
Pulp Mills
Paper Mills
Inorganic Pigments Manufacture
Industrial Inorganic Compounds, Not Elsewhere Classified (nee)
Paint and Allied Products %
Industrial Organic Chemicals, nee (plastics stabilizers)
Phosphate Fertilizers
Pesticides and Agricultural Chemicals, nee (trace elements)
Carbon Black
Petroleum Refining
Asphalt Paving Mixtures and Blocks
Gaskets, Packing, and Sealing Devices
Unsupported Plastic, Him and Sheet
3362
3369
3365
3399
3431
Laminated Plastics, Plate, Sheet, and Profile Shapes
Custom Compounding of Purchased Plastics Resins (with Cd pigments)
Plastics Products, nee
Pressed and Blown Glass and Glassware, nee
Cement, Hydraulic (dry and wet process)
Porcelain Electrical Supplies
Blast Furnaces and Steel Mills
Ferroalloy Production
Iron and. Steel Foundries
Gray and Ductile Iron Foundries
Primary Copper Smelting and Refining
Primary Smelting and Refining of Nonferrous Metals (zinc, lead, cadmium)
Secondary Smelting and Refining of Nonferrous Metals (zinc, lead, copper)
Copper Rolling, Drawing, and Extruding
Nonferrous Rolling and Drawing, Except Copper and Aluminum
Nonferrous Wire Drawing and Insulating
Brass, Bronze, Copper, Copper-Base Alloy Foundries
Nonferrous Foundries, nee
Aluminum Foundries
Primary Metal Products, nee
Enameled Iron and Metal Sanitary Ware
Fabricated Structural Metal Products (diecasting)
Bolts, Nuts, Screws, Rivets, and Washers
Plating and Polishing (cadmium electroplating}
Fluid Power Values and Hose Fittings
Valves and Pfpe Fittings, nee .
3-10
-------
TABLE 3-2. (continued)
SIC code
Industry
3585
3691
3692
3694
3714
Refrigeration and Heating Equipment
Storage Batteries
Primary Batteries, Dry and Wet
Internal Combustion Engine Electrical Equipment
Motor Vehicle Parts and Accessories
3721
3728
3952
4953
9661
Aircraft
Aircraft Parts and Auxiliary Equipment, nee
Lead Pencils, Crayons, and Artists' Materials
Refuse Systems (municipal waste combustion)
Space Research and Technology
Coal Combustion
General Laboratory Use
Oil Combustion
Wood Combustion
Natural Gas Combustion
Source: References 8 and 9.
3-11
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TABLE 3-3. ESTIMATED 1990 NATIONWIDE CADMIUM EMISSIONS
FOR SELECTED SOURCE CATEGORIES
Cadmium Refining
Cadmium Pigment Production
Cadmium Stabilizer Production
Other Cadmium Compound Production
Maior Uses of Cadmium
Cadmium Electroplating
Secondary Battery Manufacture
Cadmium Stabilizers (Plastics)
Cadmium Pigments (Plastics)
Combustion Sources
Coal Combustion
Oil Combustion
Natural Gas Combustion
Municipal Waste Combustion
Sewage Sludge Combustion
Medical Waste Combustion
Wood Combustion
Nonferrous Smeltina and Refininci
Primary Lead Smelting
Primary Copper Smelting
Primary Zinc Smelting
Secondary Copper Smelting
Secondary Zinc Smelting (scrap)
Secondary Zinc Smelting (EAF)
Miscellaneous Sources
Iron and Steel
Portland Cement Production
Phosphate Rock Processing
Carbon Black Production
Mobile Sources
TOTAL
Cadmium
Mg
4.2
1.6
3.3
NA
. NA
0.3
1.0
2.0
218.1
23.6
NA
7.0
6.2
3.6
0.4
14.3
5.6
5.7 .
4.4
1.5
NA
1.4
3.0
NA
0.07
NA
307
Emissions
4.6 .
1.8
3.7
NA
NA
0.3
. 1.1
2.2
240.4
26.0
NA
7.7
6.9
3.9
0.4
15.8
6.2
6.3
4.8
1.7
NA
1.5
3.3
NA
0.08
NA
339
Appendix A
Appendix A
Appendix A
. No emission factors
No emission factors
Appendix A
Appendix A
Appendix A
Appejndix A
Appendix A
No emission factors
Appendix A
Appendix A
Appendix A
Appendix A
Appendix A
Appendix A
Appendix A
Appendix A
Appendix A
No emission factors
Appendix A
Appendix A
No emission factors
Appendix A
No emission factors
NA =* not available
3-12
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SECTION 4
EMISSIONS FROM CADMIUM PRODUCTION
This section describes the potential sources of cadmium '
emissions from the production of cadmium and cadmium compounds. -
The following subsections, covering cadmium refining and cadmium
oxide production, cadmium pigments production, cadmium stabilizer
production, and other cadmium compounds, present process
descriptions, identify potential cadmium emission sources and
controls, and quantify cadmium emissions.
4.1 CADMIUM REFINING AND CADMIUM OXIDE PRODUCTION
Cadmium minerals do not occur in concentrations and
quantities sufficient enough to justify mining them in their own
right, but they are present in most zinc ores as cadmium sulfide
(the mineral greenockite) and are concentrated during zinc ore
processing.10 The resulting zinc ore concentrates from ore
processing contain from 0.1 to 0.8 percent cadmium by weight.10
Cadmium metal is- recovered as either: (1) a byproduct of the
extraction and refining of zinc metal from zinc sulfide ore
concentrates in electrolytic zinc smelters; or (2) the main
product in the processing of lead blast furnace dusts. Cadmium
oxide is produced in a secondary process using cadmium metal as
the feed material.
\
.Table 4-1 lists the cadmium metal and cadmium oxide
producers along with their locations, process feed materials, and
processes used. Currently, there are three plants that produce
of these three plants
4-1
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also produces cadmium oxide. All three cadmium metal refining
plants are located at electrolytic zinc smelters and include: Big
River Zinc (BRZ) Corporation located in Sauget, Illinois; Jersey
Miniere Zinc (JMZ) located in Clarksville, Tennessee; and Zinc
Corporation of America (ZCA) located in Bartlesville, Oklahoma.
Another cadmium refining plant, ASARCO, Inc., located in Denver,
Colorado> processed crude cadmium' oxide from El Paso.until the '
early 1990's, and presently produces cadmium dust. Cadmium oxide
is also produced at BRZ. (Another ZCA primary zinc smelter, in
Monaca, Pennsylvania, does not have an associated cadmium
refinery) .1:L
Reference 12 lists Proctor and Gamble Co. as a producer of
cadmium oxide. However, at the present time, it is not clear
whether cadmium oxide is manufactured at this location or whether
the company only distributes cadmium' oxide from this location.
Cadmium oxide is also produced at. Witco Chemical Company located
in"Brooklyn, New York. This plant produces cadmium oxide for its.
own use in-the production of cadmium stabilizers.
4 ..1.1 Process Deacripf i nr^O
Figure 4-1 is a general process flow diagram for the
production of cadmium metal and cadmium oxide at electrolytic and
electromotive cadmium refining plants. At the three electrolytic
zinc smelters, cadmium is removed as an impurity from the
leachate solution of the roasted zinc ore concentrate or calcine.
Cadmium is also recovered from solutions obtained by leaching
lead blast furnace baghouse dusts containing impure cadmium oxide
with a weak sulfuric acid solution". The source of the dusts
treated by the ASARCO cadmium refinery "was Godfrey roaster
baghouse dust from ASARCO El Paso.13 since the shutdown of its
lead smelter in 1985, ASARCO El Paso has continued processing
4-3
-------
ZINC ROASTER CALCINE OR LEAD
SMELTER BAGHOUSE DUST
(A)
WEAK
iULFURK
ACID
ZINC OUST ]
ELECTROMOTIVE
REFINING
|
PURIFICATION
(E)
1
+>
f
CAOMUM
PRECIPITATION
(3)
MDMUM
PURIFIED
CDSOj
r SOLUTION
CAOMUM SPONGE
PRECIPITATION
•
^
PURIFICATION
(4) STCPS
CAOMUM PLATING IN
ELECTROLYSIS CELLS
(5)
' CdMETAI,
CAOMUM
MELTING FURNACES
(7) •
ELECTROLYTIC
i
(9)
RETORT
FURNACES
CACMUM
METAL PRODUCTS
CADMIUM METAL
POWER PRODUCTS
DENOTES POTENTIAL CAOMUM EMISSION SOURCE
CAOMUM OXIDE
POWDER PRODUCT
Rgure 4-1. Row diagram for cadmium refining,1 °
4-4
-------
East Helena's blast furnace baghouse dust in the Godfrey roaster.
The Godfrey roaster was permanently closed in 1992.
The cadmium-bearing feed (Stream A) is leached or dissolved
in sulfuric acid in Step i.- Next, the sulfuric acid solution
(Stream B) is treated by various, solution purification steps
(Step 2). The purified solution (Stream C) • is treated with zinc
dust to precipitate a metallic cadmium "sponge" (Stream D)
(Step 3). The cadmium sponge is redissolved in sulfuric acid;
the solution undergoes additional purification steps to produce a
purified solution (Stream E or E'; step 4). The JMZ cadmium
refinery in Clarksville, Tennessee uses the electrolytic process
to recover metallic cadmium from the purified cadmium sulfate
solution (Stream. E). The other cadmium refineries use the
electromotive process.^
In the electrolytic cadmium refining process (Step 5),
electrolysis of the purified cadmium sulfate solution (Stream E)
deposits cadmium on cathodes. The cadmium metal (Stream F) is "
stripped from the electrodes and transferred to a cadmium melting
furnace (Step 7). The molten cadmium (Stream G) is cast into
balls and sheets for cadmium electroplating anodes or cast into
slabs, ingots, and sticks for alloying, pigment production, and
cadmium oxide production (Step 8) .
In the electromotive cadmium refining process, zinc dust is
added to the .purified cadmium sulfate solution (Stream E') to
displace cadmium as "sponge" metal (Stream F) in Step 6. The
sponge is briquetted, melted (Step 7), and cast (Step 8) into
products for sale or further processing.
JMZ and ZCA-produce only cast-cadmium metal products.
ASARCO and BRZ also produce powdered cadmium metal, cadmium
oxid?' or both •.___. Cadmium from _the _melting furnace_( stream.. G). is
4-5
-------
transferred to a retort furnace (Step 9 or 11). m powdered
cadmium production (Step 9), cadmium (Stream G) is routed to a
sealed retort that has been purged of oxygen with carbon dioxide
Cadmium vaporizes and condenses as a powder (Stream I) during
retorting in the absence of oxygen. The condensed powder is
packaged in Step 10. in cadmium oxide production (Step 11),
retorting in air oxidizes cadmium to -cadmium oxide., which is
collected in a baghouse (Step 12) and packaged (Step 13).
4.1.2 Emissions and Controlg
During cadmium and cadmium oxide production, cadmium is
emitted from melting furnaces (Step 7), retorting (Steps 9 and
11), casting and tapping (Step 8), and packaging (Steps 10 .
and 13) . Charging the leach tanks for Step l with crude cadmium-
oxide fumes (Stream A) and solutions heating tanks (Step 4). at
the Denver refinery are additional sources.
In 1986, the EPA inventoried cadmium emission sources at
cadmium refining plants based on Section 114 responses, emission
test reports, trip reports, and a previous cadmium source survey
published in 1985.14 Initially generated emissions estimates
were revised based on industry comments. Table 4-2 shows the
cadmium emission rates developed in 1986 for normal and maximum
operation at three of the four cadmium refining plants. Revised
estimates for normal operations using the same general emission
estimation methodology at the BRZ plant were made in 198915 and
are presented in the table in place of the 1986 data. However,
the data shown for maximum operation are from the 1986 study.
Revised emission estimates for the ASARCO. plant were developed in
1992 for the State of ..Colorado by JACA Corporation.13- The ASARCO
facility, had undergone substantial modifications since the 1986
study. The JACA study developed emission factors for estimating
emissions for maximum^ operation.only .L ._Thes!e_data are reported in
4-6
-------
TABLE 4-2. INVENTORY OF CADMIUM EMISSION SOURCES AND
CONTROLS FOR CADMIUM REFINING PLANTS
Plant
Company, Sauget, IL
Source
•Cadmium holding furnace
(8) Cadmium casting furnace +
tapping/casting
(1 1 ) Cadmium oxide furnace
Total Sauget
Type3
H
H
H
Emissions, kg/yr
Maximum Normal
opera- opera- Control
70. 0 UNC, L
93 76 UNC
68 < 1 BH
814 661 BH
1 ,045 737
(7-8) Cadmium melting/casting furnace H
Jersey Miniere Zinc,
Clarksville, TN
Zinc Corp.' of America, (7-8) Cadmium melting/casting furnace
Bartlesville, OK {8) Cadmium tapping/casting
ASARCO Globe,
Denver, CO
(1) Hot water leachingd
Dust charging
Reaction/Filtration
(1) Add leaching
(4) Purification
(4) Solutions heating6
Charging and pump out
Heating
(4) Sponge Production
•Premelt
Retort Building
(12) CdO production
(10) CdO packaging
(10) CdO packaging
(10) Cd packaging
•Furnaces, hoods, Cd melting, Cd
condenser
•Fugitive emissions
roadways
byproduct storage piles
Total Denver
aH 3 point source; F = fugitive source.
a H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
F
F
<1
•<1
8.8
6.1
4.3
6.1
1.7
158.5
2.1
12.7
56.6
11.6
23.2
11.2
70.8
<1
375
<1 BH, L*
<1 WS
<1 UNC
UNC
UNC
UNC
UNC
UNC
UNC
UNC
BH
BH
BH
BH
BH
BH
RS
ENC
scrubber; L =
°Based on AP-42 methodology developed for aggregate materials.
"SSSS SSTSS^Sfti ZSSSF "" * """^ hO^ "* SUbnWged fiil) and a
eDepartment currently dosed. Planning to add a vemuri scrubber when department is reopened.
•Source not depicted in Rgure 4-1.
**ln melting furnaces only.
s,
Source: References 10, 13, and 15.
4-7
-------
Table 4-2. Emission estimates for normal operation from the 1986
study are not reported in Table 4-2 because of the process and
control modifications implemented at ASARCO since then, because
of the use of new emission test data from tests conducted since
1986, and because the emission estimation methodologies used in
1986 versus the 1992 JACA study are substantially different. The
-emission sources are numbered using the same numbering scheme as
in Figure 4-1.
Cadmium melting furnaces and cadmium retort furnaces were
identified as the two types of process emission sources at
cadmium refining plants. Cadmium melting furnaces are used to
melt either cadmium sponge or sheets.10 A layer of caustic on
the molten metal surface is used to prevent oxidation of the
metal, to help remove impurities, and to provide some control of.
particulate matter at three cadmium refining plants.10 The other
plant (JMZ) uses a layer of resin to achieve the same results.10
Process cadmium emissions from the melting furnace are controlled
by a baghouse at JMZ and by a wet scrubber at ZCA.10 A hooding
system ducts fugitive emissions from the charging/drossing port
and from the tapping/casting area to the baghouse at JMZ.10 At
ASARCO, forced ventilation to a baghouse is in place during
furnace operation and during charging and tapping/casting.10
Since the 1986 study, BRZ made several improvements in their
cadmium refining process. Among these improvements, was the
ducting of the cadmium tapping/casting area of the cadmium
melting furnace to the existing lead anode furnaces' process
fugitive emissions baghouse.15
Cadmium retort furnaces are used only at BRZ and ASARCO in
the production of cadmium oxide and/or cadmium dust.10 Emissions
from these sources were estimated using'emission test data from
these plants.10 m October 1988, BRZ also made improvements to .
the cadmium oxide product collection system.1S The changes
4-8
-------
included a new product collection baghouse, a new ventilation
system and fugitive 'emissions baghouse, and an enclosed and
automated cadmium oxide packaging operation. While these changes
enhanced the operation of the cadmium oxide system, it was
assumed that no reductions in emissions were realized. The new
baghouse has the same operating parameters as the one that was
replaced.; Therefore, the test conducted in'1986 was'still-
considered to be valid and was used to develop emission
estimates. Additionally, fugitive emissions from cadmium oxide
production and packaging had been assumed to be"negligible in
1986 because at that time, the cadmium oxide production and
packaging operations were housed in a separate room within the
cadmium building; the new ventilation system probably improves
working conditions inside the cadmium oxide production and
packaging areas. ASARCO has also improved operations at the
Denver location with the addition of a baghouse to control
emissions from premelt operations and another baghouse to control
fugitive emissions from the Cd furnaces, hoods, Cd melting
operations, and the Cd condenser in the retort department.13 The
impacts of these new additions on emissions are unknown at this
time.
Because three of the four cadmium refineries are operated in
conjunction with zinc smelters, the annual emissions reported by
these plants in the 1990 Toxic Chemicals Release Inventory (see
Table 4-3} comprise the sum of both sources.7 The 860 kg
(1,896 Ib) cadmium emission reported by Big River Zinc
Corporation is slightly more than the sum of the estimates in
Reference 13 for the cadmium refining operations (737 kg) and
primary zinc smelting (100 kg). The JMZ plant reported 227 kg
(500 Ib) cadmium emissions in 1990 compared to the 1986 estimates
of
-------
™<, CADMIUM PRODUCERS REPORTING CADMIUM
EMISSIONS IN THE 1990 TOXIC CHEMICALS RELEASE INVENTORY
1 n^».^—
Plant
Asarco Inc, Globe Plant,3
Denver, Colorado
(Cadmium refinery from lead smelter
dusts)
Big River Zinc Corp.,
Sauget, Illinois
Jersey Miniere Zinc,
Clarksville, Tennessee
Zinc Corporation of America,b
Bartlesville, Oklahoma
"""""""""•'''"'""""•^'^^^•"•^^^•'•^^••••^^••^iMi^^Ml^^^^^^^^^—
TOTAL
Currently not a cadmium metal refiner.
Emissions, kg (Ib)
Nonpoint
2
(5)
smelter
113
(250)
113
(250)
23
(50)
251
(555)
i
Point
177.
(391) .
747
(1,646)
113
(250)
2,934
(6,468)
3,971
(8,7515)
Total
-• 180
(396)
860
(1,896)
226
(500)
2,957
(6,519)
4,223
(9,311)
Monitoring
Data
no
no
yes
(point)
no
zinc Passing facilities. According to ZCA, greater than
emissions resuit from the secondary zinc processina
Source: Reference 7.
4-10
-------
refinery and 12 kg for the smelter. The ASARCO cadmium refining
plant reported 180 kg (396 Ib) cadmium emissions (177 kg [391 Ibj
from point sources) in 1990.7 The differences between these
estimates '(1990 TRI and references 10, 13, and 15) are likely the
result of differences in production and in the assumptions used
to develop the emission estimates. For example, at BRZ, the
'plant personnel still use the emission factors developed from the,
1986 study to develop their" emission estimates and multiply these
factors by the production levels for the particular year. Also/
because the levels of cadmium in the zinc sulfide ore residues
vary by almost an order of magnitude, the resulting emission
estimates could also vary significantly.
Table 4-4 provides emission factors for the cadmium refining
plant using lead blast furnace dusts. These emission factors
were developed from the 1992 JACA study by using the maximum
annual emissions from Table 4-2 and dividing by the maximum
production rate data as noted in the footnotes in Table 4-4.
• - %
Emission factors for the cadmium metal and cadmium oxide
production processes are presented in Table 4-5. These emission
factors were developed based on emission tests conducted at two
of the cadmium refining plants.
4.2 CADMIUM PIGMENTS PRODUCTION
Cadmium is emitted during the manufacture of cadmium
pigments. This subsection will describe the manufacturing
process, emissions, and controls. Most of the information herein
is from a 1988 Emission Standards Division report on cadmium
emissions from pigment and stabilizer manufacture and the 1985
Background Information Document for Cadmium Emission
Sources.14'1^
4-11
-------
TABLE 4-4. CADMIUM EMISSION FACTORS FOR CADMIUM REFINING
PLANT USING LEAD BLAST FURNACE DUST
Process step (emission type3)
(1) Hot water leaching
Dust charging (H)
Reaction/filtration (H)
(1) Acid leaching (H) '
(4) Purification (H)
(4) Solution Heating
Charging & pump out (H)
Heating (H)
(4) Sponge Production (H)
*Premelt (H)
Retort Building
(12) CdO production(H)
(10) CdO packaging (H)
(10) CdO packaging (H)
(10) Cd packaging (H)
'Furnaces, hoods, Cd melting, cd
condenser (H)
'Fugitive emissions (roadways, by-product
storage piles) (F)
H — point source, F=fugitive source
b UNC » uncontrolled, BH « faaghouse, WS = wet
Emission factor
Ib/ton Cd kg/Mg Cd
produced produced
0.0297° 0.0149°
0.0207° 0.01 03°
0.0146° 0.0073°
0.0207° 0.0103°
0.0029° 0.0057°
0.535° 0.268°
0.007° 0.0035°
0.0429° 0.0214°
0.1333d 0.0667d
0.0274d 0.0137d
0.0546d 0.0273d
0.071 e 0.0355e
0.1216f 0.0608f •
0.005 1f 0.0026f
scrubber, RS = road sweeper,
°Emission factors calculated by dividing the maximum annual emissions from
sS2SSS?iSwU^5^SS"?h the 'eaching' solutions' and P™«* *
=====
Control*3
UNC
• UNC -
UNC
UNC
UNC
UNC
UNC
BH
BH
BH
BH
BH
BH
RS, ENC
.
ENC = enclosed.
Table 4-2 by the
Tabie 4-2
*Step not depicted in Rgure 4-1 .
Source: Developed from information from Reference 13.
4-12
-------
TABLE 4-5. EMISSION FACTORS FOR CADMIUM AND CADMIUM OXIDE PRODUCTION
Emission Factor
Process3
melting furnace
(8). Cadmium .
tapping/ casting
* Cadmium
holding furnace
(11) Cadmium
oxide furnace
fugitive emissions
(includes
packaging
fugitives)
(11) Cadmium
oxide furnace
Ib/ton Cdb
0.1 49C
. 0.00149
0.149
1.9x 10'4
1.30
kg/Mg Cdb
0.075C
0.00075
0.075
9.8 x 10'5
0.651
Control/ Basis
Uncontrolled. Emission
factor based on source test
Partly enclosed hood '
ducted to baghouse or wet
scrubber. Emission factor
Uncontrolled, Emission
factor
Baghouse. Based on
workroom air sampling.
Estimate based on product
S^r^f I A«***>«*m 1>«M**L* *»*.**.. ^A_.^
Method 5 sampling June
1986(n = 3). Estimated for
1988 prodn.
=====
'Numbers correspond to the steps in Figure 4-1. An asterisk denotes a step not shown in the
figure.
Based on the amount of cadmium processed. For example, for Big River Zinc Corp., 1,016 Mg
1,120 tons) cadmium was processed in 1988 to produce 1,110 Mg (1,220 tons) cadmium oxide.
(About 5 percent of the CdO produced was rejected.) All cadmium metal produced was used to
produce CdO.
C0id not use in estimating BRZ emissions from this source. Assumed negligible because of layer of
C3UST1C*
Source: Reference 15.
4-13
-------
Cadmium pigments are stable inorganic coloring agents that
provide a range of brilliant shades of yellow, orange, red, and
maroon. The pigments are based on cadmium sulfide (CdS), which
yields a golden yellow pigment. Partial substitution of'cadmium
in the crystal lattice by zinc or mercury, and of sulfur by
selenium, produces a series of intercrystalline"compounds making
up the intermediate colors .in the lemon-yellow to maroon range of
colors. Table 4-6 lists the most common cadmium pigments
produced in 1991. Table 4-7 lists the current cadmium pigment
producers.
Cadmium pigments have excellent'thermal stability which
makes them essential for use in high-temperature processing, or
where high service temperatures are encountered. Most cadmium
pigments are used in plastics, but they are also used in paints, .
coatings, ceramics, glasses, and to a lesser degree in rubber,
paper, and inks.17
There are two basic types of cadmium pigments produced in
the United States: pure pigments, based on cadmium sulfide or
cadmium selenide; and lithophone pigments, which are pure cadmium
pigments that have been diluted with barium sulfate. The pure
pigments are used undiluted when low pigment loadings are desired
as in color concentrates for plastics. Lithopones have only
one-half the tinting power of pure pigments, but when high
pigment loadings can be tolerated, lithopones offer tinting
strength and hiding power comparable, on an equal cost basis
with the"pure pigments. Their greatest use is in the coloring of
plastics with dry blends.16
4.2.1 Process • Descripf-i nn!4,16,17
•
Cadmium pigment production is based on a generic process,
4I2; However' cadniium
4-14
-------
TABLE 4-6. COMMON CADMIUM PIGMENTS PRODUCED IN 1991
C.I. Pigment
Orange 20
Orange 20: 1
Red 108
Red 108:1
Yellow 35
Yellow 35:1
Yellow 37
Yellow 37:1
Name
Cadmium suifoselenide orange
Cadmium suifoselenide lithophone
orange
Cadmium sulfoseienide red
Cadmium suifoselenide lithophone red
Cadmium zinc sulfide yellow
Cadmium zinc sulfide lithophone
yellow
Cadmium sulfide yellow
Cadmium sulfide lithophone yellow
Note: Each pigment is manufactured by all companies listed in Table 4-7, except Orange 20:1,
which is not produced by the New Jersey plant. *
TABLE 4-7. CURRENT CADMIUM PIGMENT PRODUCERS
^—
Company name
ocation
Engelhard Corporation,
Pigments and Additives Division
(Formerly Harshaw/Rltrol Partnership)
Ferro Corporation, Coatings, Colors,
and Electronic Materials Group, Color Division
Hanson Industries, SCM Chemicals, Inc.,
Subsidiary
Universal Foods Corporation, Warner-Jenkinson Company,
H.K. Color Group,
(Formerly H. Kohnstamm and Company)
Source: Reference 12.
Louisville, KY
Cleveland, OH
Baltimore, MD
South Plainfield, NJ
4-15
-------
i>
t«
Q.
•
S
1!
M I
II:
I5'
1-
•£u>S
%£~
1
CO
0)
CD
'5.
I
T3
(TJ
U
,g
o
•§
o
Q.
-------
manufacturers have developed differing proprietary procedures for
creating pigments, with specific hues and properties. These
proprietary procedures include varying types and percentages of
ingredient's, altering the calcination time, and adding or
deleting filtration, washing, drying, blending, or grinding
operations.
The source of cadmium for cadmium pigment production is a
pure solution of either cadmium sulfate, CdS04/ or cadmium
nitrate, Cd(N03)2. Cadmium sulfate is more commonly used. These
solutions are either purchased in bulk or produced on-site by
dissolving cadmium oxide, cadmium metal, or cadmium sponge (a
porous, high-surface-area form of cadmium metal) (Stream A) in
the appropriate acid (Stream B). Zinc salts (Stream C) may be
added to the dissolver (Step 1). The CdSO4 solution (Stream D) -
is then routed to a precipitation reactor (Step 2 or 2') and
mixed with varying quantities of an aqueous solution of sodium
sulfide (or other alkali sulfide, depending on the desired color)
(Stream E). This precipitates CdS in crystallographic form. To
form pigments with a red shade (cadmium sulfoselenides), the
cadmium sulfate solution (Stream E) is reacted with an alkali
sulfide-selenide (Stream G). Reds can also be produced by adding
mercuric sulfide (Stream F) to the precipitation reactor.
Cadmium pure tone pigment production (no BaSO4) is depicted
in Figure 4.2 by the path incorporating Steps 1, 2'- 5', 6", and
7". Lithopone production is represented in Figure 4.2 and also
in Figure 5 by two paths, Steps 1-7 and Steps l, 2'-8'. To form
lithopones, barium is either'added to the precipitation Reactor 2
as barium sulfide (Stream H) or added to the mechanical blender
(Step 6') as barium sulfate (stream H'). BaSO4 precipitates
along with CdS or Cd(S, Se) in Reactor 2.
4-17
-------
When the batch-process precipitation reaction is:complete,
the CdS or Cd(S,Se) precipitates (Stream I with BaSO4; Stream I'
without BaS04) are filtered from the solution, washed, and dried
in Steps 3" or 3' and 4 .or 4'. The very fine, colored
particulates (Stream J or J') do not yet possess pigment
properties. The colors and properties of the pigments develop
during their calcination, or roasting. In the calcination
process (Step S or 5'), the dried pigment precipitate material
(Stream J or J') is transferred to a furnace and heated to
between 550° and 650«C (1022° to 1202«F). This converts the
pigment material from a cubic to a more stable, hexagonal crystal
structure. In an alternative route to lithopone pigments, the
cadmium pure tone pigment produced by Step 5' may be blended in
Step 6' with barium sulfate (Stream H'}. .The calcined pigment
(Stream K, K', or K" ) is then washed with hydrochloric acid to
remove any remaining soluble cadmium particles. The product is
then washed with water, filtered, and dried (Step 6 or 7' for
lithopones; Step 6," for pure tone pigments). The cadmium
pigment emerges as a filter cake, which is either ground and •
packaged as the final product, or further processed before final
packaging. The fine, discrete pigment particles have diameters
of about l pm (range 0.1 to 3.5 /*m) .
4.2.2 Emissions and qontrolg
Cadmium is potentially emitted from the dissolver (Step l),
the precipitation reactor (Step 2, 2'), the dryer (Step 4, 4')
the calcining furnace. (Step 5 or 5'), the blender (Step 6'}, and
final product packaging (Step 7, 8', 7").. Calcining emissions
are the largest source of cadmium in the form of CdS, Cd(S,Se),
or Cd pigment (25 percent Cd in lithopone; 65 percent in pure Cd
pigment). Standard particulate matter emission controls are
used.
4-18
-------
Reactor charging for CdSO4 production (Step i) (at two
plants) is typically uncontrolled, though it is controlled by a
low-energy wet scrubber at the Louisville, Kentucky, plant.
Calcining operations are generally controlled by wet scrubbers.
Drying operations are most often uncontrolled; the Louisville
plant controlled dryer emissions with a low-energy wet scrubber."
Tray design dryers have low cadmium emissions. .Grinding,
blending, and packaging operations are generally controlled by
baghouses. 'Fugitive emissions occurring inside buildings during
the transfer and handling (loading, unloading)'of cadmium-
containing materials are typically captured by hoods and ducted
to a control device. Packaging emissions are low.14'16
Table 4-8 lists cadmium emissions reported by the inorganic
pigment plants in the 1990 Toxic Chemicals Release Inventory.7
The estimates from the 1990 .Inventory for three of the four
current cadmium pigment producers (denoted by.footnote "a" in
Table 4-8) add up to 0.83 Mg (1,838 lb).7
The results of two studies of the cadmium pigment industry
were published in- references 15 and 16. Both of these studies
estimated cadmium emissions and developed cadmium emission
factors from individual sources at each of the four plants
identified to be producing cadmium pigments. Each of the four
plants provided information through Section 114 information
requests. Additionally, site visits were made to three of these
plants and emission tests were conducted at two of the plants.
Throughout these studies, the individual plants claimed process
descriptions and all process data to be confidential business
information (CBI). As a result, emissions from each plant are
presented in these references as total cadmium emissions instead
of by individual emission source. Because the production data
are claimed to be CBI ...and a.JEormal ruling on the CBI status is
yet to be made by the Environmental Protection Agency, emission
. 4-19 ' .
-------
INORGANIC PIGMENTS MANUFACTURERS REPORTING CADMIUM
EMISSIONS IN THE 1990 TOXIC CHEMICALS RELEASE INVENTORY
Emissions, kg (Ib)
Plant
CP Chemicals Inc.
Sumter, South Carolina
Drakenfeld Colors,
Ciba-Geigy Pigments Division,
Washington, Pennsylvania
Ferro Corp.,
Cleveland, Ohio3
Ferro Corp.,
Pittsburgh, Pennsylvania
Engelhard Corp.
Louisville, Kentucky3
Johnson Matthey Inc.
West Chester, Pennsylvania (also reported
under several other possible SICs,
including 3341 , secondary nonferrous
metals)
SCM Glidco Organics Corp.
(Hanson Industries),
Baltimore, Maryland3
TOTAL
1 1 ^==»g===Ea=3^e====;=^=^=I-r=3;:3— —,-!_....-_..._.
Nonpoint
113
(250)
10
(23)
113
(250)
113
(250)
7
(15)
113
(250)
0
470
(1,038)
=======
Point
113
' (250) "'
136
(300)
45
(98)
5
(10)
590
(1,300)
113
(250)
79
a W
(175)
1,081
12,383)
Total
226
(500) '
146
(323)
158
(348)
1 1 8
1 1 \J
(260)
597
(1,315)
226
(500)
7Q
/ o
(175)
1,551
(3,421)
Monitoring
Data
no
yes
(nonpoint)
no
fin
no
no
no
nn
no
aCurrent cadmium pigment manufacturer in Table 4-7.
Source: Reference 7.
4-20
-------
factors cannot be determined for any sources in this source
category.
4.3 CADMIUM STABILIZERS PRODUCTION
Cadmium is emitted during the manufacture of cadmium
stabilizers. This subsection will describe the manufacturing
process, emission sources,, and emission controls.
Cadmium-containing stabilizers are usually cadmium salts of
long-chain organic acids. They are used in mixtures with other
metallic salts of acids to arrest the degradation processes that
occur in polyvinyl chloride (PVC) and related polymers when
exposed to heat and ultraviolet light (sunlight). Cadmium-based
stabilizers are usually prepared by mixing barium, lead, or zinc.
'organic salts with cadmium organic salts. The products are
highly effective, long-life stabilizers with ho adverse effect on
PVC processing. Cadmium stabilizers'" also ensure that PVC
develops good initial color and clarity, allow high processing
temperatures, and ensure a longer service life for the PVC. The
stabilizers contain 1 to 15 percent cadmium; the stabilized PVC
contains about 0.5 to 2.5 percent cadmium.17
4.3.1 Process Description
Cadmium stabilizer production can be a highly variable
process because many of the stabilizers are custom blended for
specific applications.
Liquid stabilizers (1 to 4 percent cadmium) are produced by
dissolving cadmium oxide in a heated solution of the appropriate,
long-chain fatty acid (e.g., 2-ethylhexanoic [for cadmium
octoate] or decanoic) and an inert organic solvent. After the
slow acid-base reaction, the solution is heated to drive off the
4-21
-------
water produced. The remaining -product is filtered and the •
cadmium soap solution is packaged in drums for -sale. In 1983,
liquid stabilizers represented about 67 percent of the cadmium
stabilizer market. However, powdered stabilizer production
offers more opportunities for cadmium emissions. 14' 1S
A process flow diagram for • manufacture of powdered cadmium
stabilizers is illustrated in Figure 4-3. The reactants are
prepared by treating the appropriate organic acid (e.g. stearic
or lauric acid) with caustic soda (Na2C03) to produce a soluble
sodium soap (Stream A) . A cadmium chloride solution (Stream B)
is prepared by dissolving cadmium, metal or CdO in hydrochloric
acid. The sodium salt of the organic acid (the -soluble soap)
(Stream A) is added to the cadmium chloride solution (Stream B)
in the cadmium reactor (Step l) at an elevated temperature
(provided by addition of steam) in the presence of a catalyst to
precipitate the cadmium soap (Stream C) . Step 2 probably
involves the addition of the' barium organic salt or its precursor
reactants. The resultant slurry is routed to a centrifuge and
dewatered (Step 3). The solid soap is washed, dried, possibly
blended, and packaged (Steps 4-7) . The final powdered stabilizer
product contains 7 to 15 percent cadmium. Additives and
moistening agents can be blended with the soap as necessary to
produce a particular end product. The number and sequence of '
blending, grinding, and packaging operations vary with the final
product.16
4.3.2 Bnisaion and Controls
Cadmium emission sources and controls during cadmium
stabilizer manufacture are summarized in this section. The
charging of powdered cadmium oxide to the organic acid solution
is a potential cadmium emission source from liquid cadmium
3
4-22
-------
en
a>
I-
• o
55
I-
co
•o 3
CQ O
O DC ~
I
ts
I
"
55
E
_3
I
ffi
03
N
.a
CD
E
3
1
•a
re
u
•a
£
«
1
•o
a
.o
o
3
1
Q.
0)
03
CD
-------
wet scrubber. Fugitive emissions are captured by hooding, which
is either ducted to baghouses or vented to the
Potential cadmium emission sources during powdered
stabilizer production include cadmium oxide production, charging
cadmium oxide to the reactor (Step l) , drying (Step 5), blending
(Step 6) , grinding (at one facility) , weighing,, and packaging
(Step 7) of the final product. The cadmium oxide production
process (one facility) is controlled by a baghouse. Reactors are
controlled by wet scrubbers. Drying operations are generally
uncontrolled. Grinding, blending, weighing, and packaging
operations are controlled by hoods and baghouses.14'16
Table 4-9 lists the manufacturers of organic chemicals who
reported cadmium emissions in the 1990 Toxic Chemicals Release •
Inventory. This list probably represents the major cadmium
stabilizer producers in the U.S. The total for all plants
producing stabilizers in Table 4-9 is 3.3.3 Mg (3.67 tons).
For similar reasons described above for cadmium pigment
manufacturers, emission factors could not be calculated for
individual process steps.
4.4 OTHER CADMIUM COMPOUND PRODUCTION
" '
The production processes used to produce cadmium pigments
and stabilizers, CdS, CdSO4, and cadmium oxide have been
described above. Rather than describe the production of a large
number of other cadmium compounds, production processes are
described only for a few .of the other compounds whose
manufacturers reported cadmium emissions in the 1990 Toxic
Chemicals -Release Inventory.7 The cadmium" compounds described
and their uses are listed in Table 4-10.
4-24
-------
TABLE 4-9. MANUFACTURERS OF ORGANIC COMPOUNDS REPORTING CADMIUM
EMISSIONS IN THE 1990 TOXIC CHEMICALS RELEASE INVENTORY
Plant
*Akzo Chemical Inc., Interstab Div.,
New Brunswick, New Jersey
(compounds Ba Cd stabilizers)
*Argus Division, Witco
Corp., Brooklyn, New York
(Ba Cd vinyl heat stabilizers)
" *Ferro Corporation,
Bedford, Ohio
(Cadmium octoate, PVC stabilizers)
Rohm & Haas Delaware
Valley, Inc., Bristol, Pennsylvania (also
reported under SIC 2821, Plastics
materials, and resins)
'Synthetic Products Co.,
Stratford, Connecticut
(compounds Ba Cd
stabilizers)
* Synthetic Products Co.,
Cleveland, Ohio
(Cadmium stearate)
*Vanderbilt Chemical Corp.,
Bethel, Connecticut
(Cadmium diethyldithio-carb'amate)
TOTAL
=========================S-— S3===-— s—
Emissions,
Nonpoint
P
2,180
(4,805)
113
(250)
2
(5)
1
(1)
113
(250)
1
(3)
2,410
(5,314) (2
=======
kg (Ib)
Point
226
" (500)
342
(755)
113
(250)
o
w
113
(250)
113
(250)
13
(28)
920
,033)
=======
. ================
Monitoring data
Total
226 no
(500)
2,522 no
(5,560)
226 no
(500)
2WA0
yes
(5) (nonpoint)
114 no
(251)
225 no
(500)
14 no
* ™ 1 1 \J
(31)
3,330
(7,347)
'Assumed to be cadmium stabilizer manufacturers.
Source: References 17 and 18.
4-25
-------
TABLE 4-10. OTHER CADMIUM COMPOUNDS AND THEIR USES
Compound
Cd (OH),
Cd (NO;,).,
CdCO;,
Cd (CN)?
CdCI2
Cdl?
CdTe
CdSe
BMMtanaaEKsass
Uses
Used to prepare negative electrodes for nickel-cadmium batteries
Imparts a reddish-yellow luster to glass and porcelain ware.
Starting compound to produce other cadmium salts.
Used in copper bright electroplating; byproduct of cadmium electroplating.
Used in photography, dyeing, calico printing, and solutions to precipitate
suifides.
Used in photography and process engraving.
Used for semiconductors and photoconductors in solar cells, and infrared,
nuclear-radiation, and gamma-ray detectors.
Used for semiconductors and photoconductors; noted for fast response time
and high sensitivity to longer wavelengths of light.
Source: Reference 19.
4.4.1 Process Descriptions
Cadmium hydroxide, Cd(OH2), is produced by adding a solution
of cadmium nitrate, Cd(NO3)2, to a boiling solution of sodium or
potassium hydroxide (NaOH or KOH). The cadmium metal, oxide,
hydroxide, or carbonate is digested with nitric acid followed by
crystallization to produce cadmium nitrate.20
Hydrated amorphous cadmium carbonate, CdC03/ is precipitated
from cadmium salt solutions by adding sodium or potassium
carbonate. Heating amorphous cadmium carbonate with ammonium
chloride at 150° to 180°C (302°F to 356°F) in the absence of
oxygen gives the crystalline form. Anhydrous cadmium carbonate
is prepared by adding excess ammonium carbonate to a cadmium
chloride solution followed.by drying the precipitate at 100°C
(212°F) .20
4-26
-------
Cadmium cyanide can be formed In-situ as a by-product by
dissolving cadmium oxide in excess sodium cyanide electroplating
solution.20
Hydrated cadmium chloride, CdCl2.5H20 can be prepared by
reactions in aqueous?solution between hydrogen chloride, HC1, and
cadmium metal or a compound such as CdC03, CdS, CdO, or Cd(OH)2. •
The reaction solution is then evaporated to recover crystals of
the hydrated salt.20
Anhydrous cadmium chloride, CdCl2/ may be prepared by
several methods:20
1. Refluxing the hydrate with thionyl chloride, SOC12.
2. Calcining the hydrate (removes H2O) in an atmosphere of-.
HC1 gas.
3. Chlorinating dry cadmium acetate, CdO2CCH3, with acetyl
chloride, CH3COC1, in glacial acetic acid (CH3C02H)
4. Mixing hydrated cadmium nitrate, Cd(N03)2.4H20, with hot
concentrated hydrochloric acid and removing CdCl2 by distilling
the solution.
5. Treating cadmium metal with chlorine gas.
6. Treating cadmium metal with hydrogen chloride gas.
Cadmium iodide, Cdl2, is prepared by dissolving cadmium
metal or a compound such as CdO, Cd(OH)2, or CdC03 in hydroiodic
acid (HI). The beta form is recovered by slow crystallization
from solutions or from fused salt mixtures.20
Cadmium telluride, CdTe, may be produced by one of three
processes:20 . .
1. • Combining elemental cadmium and tellurium at high
temperatures
4-27
-------
„ 2* Treatin* solutions of cadmium salts with hydrr-aen
tellurzde gas (H2Te) ~
telluL Tatln9 S°1Utl0nS °f cadmium "It. with an alkali
telluride (e.g., with Ha2Te or K2Te) .
Producers of cadmium chemicals not discussed in other
subsections are listed in Table. 4-n.
4-4-2 Eroissiong anri
Information on emissions and controls in place at th.«.
Plants was not readily available. Cadmium emissiol lght L
ected from processes in which solutions are heated aid in
Tl?™- H°WeVer' °nly thrSe °f "- ^ucers listed
invn 4-" ™erS fOUBd in the "SO Toxic Chemicals Release
Talle H;," Ty ^ °f thSm reP°rted Ca
-------
Chemicals,
strial Gases Division Specialty
., Hometown, PA
rg,NJ
ries. Inc.
Division, St. Louis, MO
p., Somerset,
Carson, CA
»mi, OK
Catalysts and
Is Division, Cleveland, OH
iponents
g and Sales Operation,
d, OH
smpany,
ly, Danvers, MA
ical Works, Inc.
(CH3)2Cd {dimethyicadmium)
CdCl2, CdSO4
- CdCl2 Cd(BF4)2, CdS04
CdCl2
Cdl2
CdS, CdTe
CdCl2, Cd(BF4)2, CdS04, CdWO4
CdSe, CdS
Cd(NO3)2
CdTe
Cd acetylacetonate
-%
ional, Inc., Specialty Chemicals CdS, (CH3)2Cd
sd Materials, CVD, Inc.
>urn, MA
Chemicals,
P. Chemicals Subsidiary
n, NJ
lical Company,
atf, OH
t, Inc.,
bilt Chemical Corp. Subsidiary,
CT
Cd(BF4)2
Cd(NO3)2
Cd(C03)2, Cd(OH)2, Cd(N03)2
Cd dietnyldithiocarbamate
we 12.
!om are
strial
Lxiin and
Je are:
lattery
s and
This
each
a to the
2SS.
.sting
un
Y
y for
id for
2 in
ed
os ion
rical
2 used
red.
ift
and.....
4-29
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TABLE 4-12. MANUFACTURERS OF INORGANIC COMPOUNDS REPORTING CADMIUM AIR
EMISSIONS IN THE 1990 TOXIC CHEMICALS RELEASE INVENTORY
Emissions, kg (Ib)
Plant
Nonpoint
Point
American Microtrace
Corp., Fairbury, Nebraska (micronutrients
for agriculture)3
CP Chemicals Inc.
Sumter, South Carolina
(Cadmium nitrate)
Hall Chemical Company, Arab
Plant, Arab, Alabama (Cadmium nitrate)
Shepherd Chemical Company,
Cincinnati, Ohio (Cadmium carbonate,
hydroxide, nitrate)
Total
Monitoring Data
0.5
(1)
2
(4)
2.5
-(5)
no.
no
no
no
1 slab "«• oalvanir.r-s dross. or baghouse dust from the brass
* °f CadmiUm' ' 3nC SU'faW ^^ °> *• — « ls
Source: References 12, 15, and 17.
4-30
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SECTION 5
-''
EMISSIONS FROM MAJOR USES OF CADMIUM
Emissions from industrial processes that use - cadmium are
discussed in this section. 'Based on the 1991 U.S. industrial
demand figures presented in Figure 3-1, Section 3, cadmium and
cadmium compounds have four major commercial uses. These are:
(1) electroplating, (2) secondary (i.e., rechargeable) battery
manufacture, (3) heat stabilizers for synthetic materials and
plastic resins, -and (4) pigments for plastic products. This
section is divided into four subsections, one devoted to each
major use. Each subsection presents a brief introduction -to the
industry and a general discussion of the production process.
Where cadmium is used in the process, descriptions of existing
cadmium emission control measures and estimates of cadmium
emission factors are given. The level of detail will vary
according to the availability of information, particularly for
emissions where data may be incomplete or absent.
5.1 CADMIUM ELECTROPLATING
In 1991, cadmium electroplating applications accounted for
approximately 20 percent of the total demand for cadmium.22 m
cadmium electroplating, a thin layer of cadmium is deposited
directly over a base metal (usually steel) to provide corrosion
protection, a low coefficient of friction, and a low electrical
contact resistance., in addition, cadmium coatings also are used
in the electrical industry because cadmium is easily soldered.
Cadmium electroplating'is performed on such items as aircraft
.fasteners, cable .connectors.for^computer^^ship^components, and
5-1
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automobile engine components. Table 5-1 presents the major
market areas for cadmium coatings.23
TABLE 5-1. MARKET AREAS FOR CADMIUM COATINGS3
Market area
Electronics and communications
Automotive parts
Aircraft/aerospace fasteners
Industrial fasteners
Ordinance
Shipbuilding
Hardware (hinges, etc.)
Household appliances
Source: Reference 23.
aBased on 1989 data.
Percentage of all cadmium
coating products, %
22.5
30.0
12.5
17.5
6.0
5.0
An estimated 1,200 metal finishing job shops that perform
cadmium electroplating operate in the United States.24 Metal
finishing shops are typically located at or near the industries
they serve. Therefore, the geographical distribution of the
metal finishing shops closely follows that of the manufacturing
base in the U.S.24
5.1.1
Process Degcripfinn
A flow diagram for a typical cadmium electroplating process
is presented in Figure 5-1. Prior to plating, the parts undergo
a series of pretreatment steps to smooth the surface of the part
and-to-remove any surface soil, grease, or oil.--.. Pretreatment
steps include polishing,LJ[^ndin^^nd/or degreasing of the part
5-2
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SUBSTRATE TO BE
PLATED
PRETREATMENT STEP
(POUSHING,
DECREASING)
CLEANING
I
RINSE
ACID DIP
I
RINSE
CADMIUM
ELECTROPLATING
POTENTIAL CADMIUM
EMISSIONS
RINSE
ELECTROPLATED
PRODUCT
I
POST-TREATMENT
Rgure 5-1. Cadmium electroplating process.
5-3
-------
to prepare for plating. The part being plated is rinsed after
each step in the process to prevent carryover of solution that
may contaminate the baths used in successive process steps.
Polishing and grinding are performed to smooth the surface
of the part. Degreasing is performed either by' dipping the part
» organs solvents or by vapor degreasing the part using organic^
solvents. vapor degreasing is typically used when the surface
loading of oil or grease is excessive. The two organic solvents
most commonly used for cleaning applications are
trichloroethylene and perchloroethylene.
alkaline cleaning is sometimes used to dislodge surface soiJ
and prevent lt from settling back onto the Tnetal. These cleaning
solutions are typically made up of compounds, such as sodium
carbonate, sodium phosphate, and sodium hydroxide; they usually
contain a surfactant. Alkaline cleaning techniques include
soaking and cathodic and anodic cleaning.
formed^ !?" T "" "** " "*"• "* Carnlsh °r oxlde
formed on the alkaline cleaning step and to neutralize the
al.kal.ne film. Acid dip solutions typically contain from 1C to
30 percent by volume hydrochloric or sulfuric acid in water.
The exact pretreatment steps used depend upon the amount of
rts fTT' " Oil °D thS Par"- P°llowin3 Pretreatment, the
parts are transferred to the plating tank.
several cadmium plating bath formulations are used to
"
cyde ba «' » «
cyanide bath is the predominant formu-lation used to deposit
antcTfl°T bSCh f0mlUlati°- «— *«*- a neutrL sulfate,
an acid fluorborate, or an acid sulfate bath. Currently, the use
«* these other bath formulations. .is not ^appreciable becLe the
5-4
-------
cadmium deposits formed from these baths are not of sufficient
quality (i.e., do not display the desired physical properties) to
gain widespread acceptance. Therefore, the following discussion
will focus on the cadmium cyanide plating bath.
Table 5-2 presents the bath composition.and operating
•parameters- of the cadmium cyanide bath.25 In cadmium plating, -
the part(s) is placed in a tank and connected into the electrical
circuit as the cathode. If small parts are to be plated", the
parts are first placed in a plating barrel or on a plating rack.
The barrel or plating rack is then placed in the tank and
connected into the electrical circuit. As current is applied,
cadmium ions in the solution are drawn to the negatively-charged
cathode where they undergo reduction, resulting in the cadmium
being deposited on the part. The efficiency of the plating bath"
is based on the amount of current that is consumed in the
deposition reaction versus the amount of current that is consumed
by other side reactions. For cadmium plating baths, the cathode
efficiency typically ranges between 90 to 95 percent; therefore,
90 to 95 percent of the current supplied to the tank is consumed
in the deposition reaction. The remaining 5 to 10 percent is
consumed by other side reactions, such as the evolution of
hydrogen gas at the cathode and the evolution of oxygen gas at
the anode.
Following plating, the part is thoroughly rinsed. Most
cadmium plated products do not require any further treatment;
however, some parts are often post-treated with a bright dip.
This dip is a chromate conversion-coating, which is colored,
painted, or lacquered, depending upon the part specifications.
5-5
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TABLE 5-2. COMPOSITION AND OPERATING PARAMETERS OF CADMIUM CYANIDE
PLATING BATH
Component
Composition of bath. a/L
Cadmium
Cadmium oxide
Sodium carbonate
Sodium cyanide
Sodium hydroxide
Operating parameter?
Current density, A/m2 (A/ft2)
Temperature, °C (°F)
Cathode efficiency, %
Type of anodes used
Anode efficiency, %
Operating range
20 (2.7)
22' (3.0)
30-60 (4.0-8.0)
101 (13.5)
14 (1.9)
54-970 (5-90)
15-38 (60-100)
90-95
Cadmium
100
Source: Reference 25.
5.1.2 Emission Control,
No air pollution control measures are currently being used
on cadmium electroplating tanks. Local exhaust ventilation is
sometimes used on these tanks as a precautionary measure against
worker exposure.
5.1.3 Emissions
Based on the ventilation guidelines published by the
American National Standards Institute .(ANSI), the emission
potential from cadmium electroplating tanks is extremely low.
Cadmium cyanide electroplating tanks are given a hazardous
classification of D-4, the lowest possible rating.26 m the 1990
Toxic Chemical Release Inventory (TRI), 41 facilities reported
cadmium emissions under SIC 3471, Plating and'Polishing.7 Total
cadmium emissions reported from these facilities equaled 1,612 kg
(3,554 Ibs). However, it should be noted that 25 percent of the
facilities account f6r 98 percent of the- emissions. ' Fifty
percent of the facilities reported zero emissions, and-25 percent
5-6
-------
reported less than 10 Ib/yr of cadmium emissions. A review of
the facilities with the higher emission estimates revealed that
some of the facilities were manufacturers of plating bath
chemicals and hot cadmium plating facilities. No additional data
are available regarding cadmium emissions from cadmium
electroplating tanks.
5.2 SECONDARY BATTERY MANUFACTURE
Cadmium is used in the production of several types of
secondary (rechargeable) batteries. In 1991, this area accounted
for approximately 45 percent of the total demand for cadmium.22
This subsection focuses, on emissions and controls during
production of nickel-cadmium batteries, the largest segment of
the cadmium battery industry. Other battery types that use
cadmium include silver-cadmium batteries, which have aerospace
applications, and mercuric oxide-cadmium button cells.
Information was not available on the potential for cadmium
emissions fro.m these other battery types.
Nickel-cadmium cells are manufactured in a variety of forms
and sizes for principally two applications: industrial and
portable batteries. Nickel-cadmium batteries for industrial use
are usually the vented (or open) or semi-sealed type and may be
either pocket plate, sintered plate, or fiber structured
construction. Vented (open) cell designs are currently used for
larger-sized cells designed for industrial or other heavy duty
applications. In these applications, the batteries are subject
to frequent charging and require addition of electrolytes after
long periods of operation. Applications for the industrial
batteries include several railway uses (e.g., locomotive
starting, emergency braking, signals and warning lights), standby
power for alarm systems, emergency lighting, military - —
5-7
-------
communications, solar energy storage, navigation equipment,
hospital operating rooms, and aeronautical applications.17
Sealed-cell nickel- cadmium batteries designed for portable
applications (e.g., toys, camcorders, portable tools, and
cellular telephones) usually are constructed using sintered plate
electrodes. These cells are manufactured in cylindrical, -button,
and prismatic shapes; they may be recharged up to 2,000 times,
and require no maintenance.17
Eight primary producers, their plant locations, battery
type, and processes used were identified in an EPA report.14 The
information on company name and plant locations was updated using
emission reports from the 1990 TRI and is presented in
Table 5-3.7 in addition to these primary producers, some
companies may assemble nickel-cadmium batteries using imported
components.
5-2.1 Process Descripf-i rm
Nickel-cadmium cells utilize a reversible electrochemical
reaction between cadmium and nickel electrodes packed in an
alkaline electrolyte (potassium or lithium hydroxide). The
electrolyte does not take part in the charge/discharge reactions,*
it acts only as a charge carrier. During discharge, the cadmium
is oxidized to cadmium hydroxide at the cathode, and hydrated
nickel (ill) oxide is reduced to nickel (II) hydroxide at the '
anode. The principal difference between the various types of
nickel-cadmium cells is the nature of the cell electrodes. Three
types of positive electrodes (anodes) are used: pocket plate,
sintered plate, or fiber plate. The hydrated nickel oxide at'the
anode is usually in powder form and is held in pocket plates or
suspended in a gel or paste and placed in sintered or fiber
electrodes. Negative electrodes (cathodes) use pocket plate,
5-8
-------
TABLE 5-3. NICKEL-CADMIUM BATTERY PRODUCERS-1990
Company
Eagle-Picher Industries, Inc.,
Colorado Springs, CO
Eveready Battery Company, Inc.
Cleveland, OH
Greenville, NC
Gates Energy Products, Inc.
Gainesville, FL
GNB Industrial Battery Company
Ft. Smith, AR
Kankakee, IL
Marathon Power Technologies
Waco, TX
Saft America, Inc.
Valdosta, GA
Battery type
Sealed
X
X
X
X
X
X
X
Vented
X
X
X
X
=====
Process
Sintered
Wet
Dry
Wet
X
X
Assembly only
Wet
======
Pocket
X
Source: References 7 and 14.
sintered powder, fiber plate, foam or plastic banded supports to
hold the cadmium hydroxide in place. Graphite or iron oxide is
commonly added to improve the conductivity of both the nickel and
cadmium hydroxide.17
A description of the sintered plate wet process for nickel-
cadmium battery production is presented in this subsection. A
flow diagram for the process is shown in Figure 5-2. This
process appears to have the greatest potential for cadmium
emissions as reported by the industry in the 1990 TRI survey.7
Descriptions were not available for the other production
processes.
In sintered-plate formation, nickel powder is heated on a
nickel-plated steel strip to give a porous medium bound to a
base. Heating the nickel powder at high temperatures welds
5-9
-------
MCXH.-PIATEDSTEH.
NICKEL POWO6R
PRESS DRY CADMIUM
POWER AND BINDER
ONTO WIRE MESH
• DENOTES POTENTIAL SOURCE OF CADMIUM EMISSION
KCHLOH
TEST AND PACK
^
REJECT CELLS
PRODUCT
Rgure 5-2. Simplified flow diagram for ^^
5-10
-------
together the contact points of the nickel powder grains. During
the impregnation steps, solutions of nickel or cadmium impregnate
the void spaces of the sintered nickel. During the nickel
impregnation, the sintered plate is soaked with a saturated
solution of nickel nitrate in nitric acid. The .cadmium
impregnation step is similar, except that the saturated solution
contains cadmium nitrate. The cadmium nitrate solution may"be
prepared onsite from cadmium oxide or purchased.27
The impregnated plates are dried and then immersed in a
potassium hydroxide solution to convert the nickel and cadmium
salts to their respective hydroxides. The anodes (with nickel
hydroxide) and .cathodes (with cadmium hydroxide) undergo a series
of steps before being assembled into cells and then batteries:
washing and oven drying, final caustic soak, hot deionized water-.
rinse, forming in caustic, and final brush and rinse.14'27
Two. alternative methods for impregnating the cathode are
used. In one method, the cadmium is electrolytically deposited
from a standard cadmium electroplating solution onto the sintered
plate. The cadmium-plated sintered strip is then rinsed and is
ready for assembly. In another method for cathode production,
dry cadmium powder and a binder are pressed on wire mesh in a
mold and transferred to the assembly steps.14'27 Since the
individual cells are precycled before assembling into batteries,
it is not important whether the cathodes are originally
impregnated with Cd(OH)2 (the product of discharge reactions) or
Cd (the product of charging reactions). The reactions are as
follows:
discharge
2 0-NiOOH + Cd + 2H20 '
charge
Ni(OH)2 + Cd(OH)2.
5-11
-------
Cd + 2OH
discharge
Cd(OH)
, charge
During assembly, the nickel -containing anode and the
cadmium- containing cathodes are assembled alternately into cells
with felted nylon cellulose separators, and the cells are
•assembled into battery cases of plastic or nickel-plated steel.
The electrolyte containing potassium hydroxide and lithium
hydroxide is added to the assembled components in the battery
case. The separator material holds the electrolyte, as well as
separates the negative .and positive electrodes. The batteries
finally undergo testing and packing; failed batteries are
rejected.14'27
5.2.2 Emission Control
In a nickel -cadmium battery plant, the most common forms of
cadmium emitted are cadmium nitrate, cadmium hydroxide, and
possibly cadmium oxide. All air emissions of cadmium compounds
will occur as particulate matter- -and primarily as fugitive
emissions due to material handling and transfer procedures, oven
drying operations, and cell assembly.
The predominant control methods used in the industry are:
(1) hoods and vacuum systems ducted to dust collectors and
(2) fabric filters in cadmium handling areas. Fabric filters are
known to be highly effective particulate removal devices,
especially for the lower temperature emissions anticipated for
this industry. At most facilities, fugitive emissions are
contained within the plant and are captured .and sent to a control
device .
5-12
-------
5.2.3 Emissions
Cadmium is potentially emitted from several, steps -in the
manufacture of"nickel-cadmium batteries. Potential emission
sources were noted with a solid circle in Figure 5-2. Operations
involving the handling of dry cadmium salts and''powders, oven
drying, and cell assembly are the likeliest sources.
Solution preparation is also a potential source of cadmium
emissions. If the sintered .plates are to be impregnated with
cadmium nitrate solution, cadmium may be emitted by the handling
of dry salts during solution preparation. Preparation of the
. cadmium-containing electrolyte for the electrolytic deposition
also would emit cadmium if dry material is used. If the cathode
is prepared by the dry-pressing process, handling of dry cadmium.
powders and pressing the cadmium powder into the grid are
potential emission sources. Oven drying of cathode plate
material and the cell assembly step also are potential cadmium
emission sources.
No cadmium emission factors have been published for the
nickel-cadmium battery production process, nor are any emission
. test data available that would allow the calculation of emission
factors. A 1985 background document.on cadmium emission sources
estimated nationwide emissions from battery manufacturing at
100 kg/yr (220 lb/yr).14 In the 1990 TRI, the eight battery
production sites shown in Table 5-3 reported a total annual
cadmium release of 316 kg (697 lb).7 Based on these data, the
production of nickel-cadmium batteries does not appear to be a
major source of cadmium emissions.
5-13
-------
5.3 CADMIUM STABILIZERS FOR PLASTICS
Cadmium compounds, in conjunction with barium compounds,
have been widely used as an effective heat stabilizer system for
polyvinyl chloride (PVC) and related polymers. .Polyvinyl
chloride is generally regarded as one of the most versatile of
polymers because of its compatibility with many other materials, '
such as plasticizers, fillers, and other polymers. The major
disadvantage is its poor thermal stability. The physical
appearance and performance properties of PVC can be modified by
the incorporating additives, but nothing can be done to
completely prevent polymer decomposition by physical or chemical
means. Additives classified as stabilizers can effectively
hinder and reduce the degradation process until it essentially
ceases, but a breakdown under the action of physical and chemical
agents is always present to some degree. . Several mechanisms have
been proposed as routes for PVC destruction. These mechanisms
are quite similar chemically and can be directly related to the
physical state of the PVC. Dehydrochlorination is the most
significant cause of degradation in PVC. The process can be
initiated either by loss of a labile-chlorine atom or through a
free radical reaction with the resultant formation of a double
bond. AS dehydrochlorination continues, conjugated double bonds
are formed, resulting in a shift in the wavelength of light
absorbed by the polymer. The wavelength of absorbed light
changes according to the number of conjugated double bond systems
that are present, and the color of the polymer changes from light
yellow to dark yellow to amber to reddish-brown and finally to
black.28
Stabilizers are usually inorganic or organometallic
compounds, whose names reflect the cations involved. The major
classes of stabilizers are based on tin, lead/and a mixture of
Group II metals, such as barium, cadmium, atnd zinc. The Group II
5-14
-------
metal (mixed metal) stabilizers have progressed over the years
from simple additions of barium succinate and cadmium palmitate
to complex blends of barium/cadmium/zinc soaps, organophosphites,
antioxidants, solvents, extruders, peptizers, colorants, • -
ultraviolet (UV) absorbers, and many other constituents. Cadmium
stabilizers were initially used because they impart clarity and
retention of initial color to: a PVC formulation. The long-term
heat stability supplied by cadmium and zinc is much less than
that offered by barium compounds. Cadmium stabilizers are
functionally dependent upon the anions, and the anions are a
major factor that affects properties, such as lubricity, plate-
out, clarity, color drift, and heat stability. Common anions for
cadmium are the 2-ethylhexoate (octoate)> phenate, benzoate, and
.stearate.28
Cadmium/barium stabilizers are commercially available in
liquid or solid form. Liquid stabilizer systems are easier to
handle and do not result in plate-out problems, which may occur
with the powdered systems. The liquid stabilizers usually have a
lower cadmium content (.1 to 4 percent) and are cheaper on a
weight basis. Solid stabilizers have a higher cadmium content (7
to 15 percent) and are more effective than liquid stabilizers on
a weight basis.31
In these mixed metal stabilizer systems, the cadmium content
ranges from l to 15 percent, and the stabilizer system
constitutes between 0.5 to 2.5 percent of the final PVC
compounded resin.17 Most cadmium-containing stabilizer systems
are barium/cadmium-zinc based mixtures; these systems are being
replaced with barium/zinc products. The successful replacement
of cadmium-containing products depends principally on the use of
higher barium-to-zinc ratios than barium-to-cadmium ratios and
the anion chemistry, which compensates for the smaller size of
_.the z±nc. a.11.0™ c°mPared_t..91.the cadmium atom.29 ..An .estimated 30
5-15
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to 35 percent of the cadmium-containing stabilizer usage in the
U.S. has changed to noncadmium products, and this percentage is
expected to increase to more than 50 percent by -the end of
1992.30
5.3.1 Process
The addition of heat stabilizer additives occurs as part of '
the overall production of the formulated PVC resins. Formulation
of the resin normally uses a blender system and, depending upon
the particular PVC product, may be a batch'or continuous
operation. Solid cadmium stabilizer systems may be added
directly to the dry PVC resin and then thoroughly mixed with the
resin particles. Liquid cadmium stabilizers may be added
directly to the resin or mixed with a liquid plasticizer prior to
addition to the resin. The particular sequence of stabilizer
addition depends upon the processing method to be used (e.g.,
calendering, extrusion, dipping'). After all additives, including
the stabilizer -have been incorporated, the•formulated resin is
usually a free-flowing powder or granule with the liquids
adsorbed on the resin particles.
The most common us.age of cadmium-based stabilizers is for
flexible and semi-rigid PVC applications.^ in general, cadmium-
based stabilizers are used in the production of flexible and
semi-rigid PVC products. These PVC products are processed by
calendering, extrusion, or injection molding techniques.28
Cadmium-based stabilizers find limited use in rigid PVC products
or films for electrical uses. Liquid cadmium stabilizers may be
used In production of the following types of PVC products:
1. Flexible or semi-rigid injection molded;
2. Clear plastisols;
3. Thin gauge or lightly filled calendered films;
5-16
-------
4. Clear and lightly, filled extruded films or sheets; and
5. Dipping operations.
Solid cadmium-based stabilizers may be used in highly filled
calendered sheet (e.g., floor tile) or other calendering,
injection molding, or extrusion processes to manufacture filled.
(i.e., nonclear) PVC products. • ' '
5-3.2 Emission Control
No information is available for the specific types of
emission control devices used to control cadmium emissions
resulting from production of PVC products. One manufacturing
facility using cadmium stabilizers indicated that the major
emission source would be due to materials handling.32 This
source presumably would be in the resin formulation area and if a
small batch operation were used, during transfer of the
formulated resin. Most solid cadmium stabilizers are produced in
forms (e.g., flaxes, pellets) to reduce dust emissions during
handling.
Cadmium emissions from the processes of extruding, molding,
and calendering are probably minimal since the temperatures
necessary to volatilize significant quantities of cadmium
compounds would thermally destroy the resin and other organic
constituents.
5.3.3 Emissions
Cadmium emissions may occur when cadmium-containing
stabilizers systems are added to PVC resins during formulation;
prior to processing the PVC resin. Although use of cadmium in
the production of stabilizers constitutes about- 12 percent of the
_f°?_ ^5?iuE'- the; emission,, of _cadmium,. resulting from
5-17
-------
the use of the stabilizers during resin formulation had not been
considered a potential source. Table 5-4 presents cadmium
enussions by several manufacturers of formulated resins and
plastics reported in the 1990 TRI.? some of these facilities are
probably also using cadmium-based pigments-in trhe resins, but the
reporting system in the TRI does not easily distinguish between '
the two-cadmium products. • Thus, .some of the cadmium emissions
may result from .pigment usage.
No emission factors are published for this process, and no
test data are available to allow calculation of an emission
factor.
5.4 CADMIUM
IN PLASTICS
About 80'percent of all cadmium-based pigments is used in
the plastics industry. The other 20 percent is used mostly for
the coloration of paints, coatings, ceramics, and glasses.33 m
the plastics industry, pigments and other additives are blended
wzth the resins before the plastics products are manufactured
Thxs blending step can be done in conjunction with other
manufacturing steps at the production site, Alternatively
custom-blended resins can be purchased from another company and
transported to the production site. This is a common practice
for smaller companies or for specialty products. Table 5-5 lists
manufacturers of custom compound purchased resins who reported
emissions of cadmium in the 1990 TRI.? Most of this
pigments with resins. arenas
The costs of purchasing custom compounded resins have risen
to a level where some producers of plastic goods have changed to
blending their own resins. This shift in production- locale-may
be particularly true for users of cadmium pigments, because these
5-18
-------
TABLE 5-4. REPORTED CADMIUM EMISSIONS BY MANUFACTURERS OF
FORMULATED RESINS AND PLASTIC PRODUCTS
Company
Rohm & Haas, Inc.
Gencorp Polymer Products
General Eiectnc Plastics
Synthetic Products Company
Monsanto Company
General Eiectnc Chemicals
Huls America, Inc.
Franklin Burlington Plastics
O'Sullivan Corp.
North American Plastics, Inc.
Vytron Corp.
Standard Products Company
RJF International Corp.
Achilles USA, Inc.
IPC Corinth Division, Inc.
Regalite Plastics Corp.
<======= = = =— =S==SSS==
Location
Bristol, PA
Newcomerstown, OH
Selkirk, NY
Stratford, CT (2)
Cleveland, OH
Addyson, OH
Washington, WV
Mountain Top, PA
Burlington, NJ
Lebannon, PA
Winchester, VA
Yerington, NV
.eominster, MA
"rairie, MS
.oudon, TN
Winnsboro, SC
Marietta, OH
Everett, WA
Corinth, MS
'edricktown, NJ
Newton Upper Falls,
MA
TOTAL
=======
Reported emissions
kg
2
5
8
118
227
5
1
113
227
5
. 5
5 -
43
5
113
2
5
16
113
24
5
1,047
ib
5
10
16
261
500
11
2 • I
250 I
500
10
!o°
94 I
10 ||
250
5
10
35 I
250
52
10
2,301 I
Source: Reference 7.
Note: In addition to the companies and locations shown in the table, 16 additional companies or
locations reported zero cadmium emissions.
5-19
-------
TABLE 5-5. REPORTED CADMIUM EMISSIONS BY PRODUCERS OF
CUSTOM COMPOUNDED RESINS
Company
Plastics Color Chip, Inc.
Reed Plastics Corp.
General Color and Chemical
Company
feknor Apex Company
Hoachst Celanese
Quantum Chemical Corp.
Location
Ashboro, NC
Calumet City, IL
Jeffersontown, KY
Albion, Ml
Hoiden, MA
Minerva, OH
Akron, OH
Norwalk, OH
Ft. Worth, TX
:lorence, KY
Gastonia, NC
St. Peters, MO
Somerset, NJ
Elk Grove Village, IL
'awtucket, Rl
^orence, KY
Fairport Harbor, OH
TOTAL
""""^^^••ggigail.- - -mlm*^^**^^HI^^^-i*—
Emissions
kg
227
116
116
2
2
113
5
227
116
116
227
227
116
116
5
5
227
1,963
sseaesss—
Ib
500
255
255 .
5
5
250
10
500
255
255
500
500
255
255
10
10
500
4,320 I
Source: Reference 7.
, 5-20
-------
pigments are expensive and have advantages of easy mixing and
rapid, even spreading.
5.4.1 Process Descript^ipn34
Most commercial pigments have an average particle size in
the range of 10'3 to'10'5 mm "(0.01 to 1.0 ji) . The dry pigment
powders are usually agglomerated before sale in order to reduce
material loss during transport. These agglomerates must be
dispersed by the compound resin manufacturer, either before or
during processing. The initial step in dry pigment dispersion is
wetting of the pigment surface. Subsequent steps are breaking
down of agglomerates, distribution of the particles in the resin,
and stabilization of the dispersion'.35 since cadmium pigment
loss would be minimal after the dry pigment is wet, this
discussion focuses on materials handling.
Bulk materials can be stored in outdoor silos, boxes, bags,
or drums. Large vacuum pumps transport materials from railcar or
truck to silos. Smaller vacuum pumps transport materials from
onsite storage in bags, drums, and boxes to the hopper loaders of
process machinery, if not to the machines themselves. Vacuum
lines enter hoppers tangentially so that the material can be
separated from the conveying air stream. An external ratio
mixing valve is usually located at the inlet of each vacuum
hopper to allow regrinds and other recycled material to be
proportionally mixed with virgin material prior to processing.35
5-4-2 Emission Control
According to conversations with company officials at
production plants, it was determined that cadmium emissions
originate primarily from materials handling.36'37
5-21
-------
Hand methods of blending materials can waste up to
25 percent of purchased colorants. Automatic methods,:such.as
metering, mixing, and vacuum transport, substantially reduce
waste and emissions. Emissions of powdered materials from vacuum
hoppers are usually controlled with filters and .floor-mounted
dust collectors. All cadmium emissions, as cadmium pigments,
would be in a particuiate form so the use of dust*filters and
dust collectors should be an effective emission control measure.
However, there are no test data available to substantiate the
effectiveness of these controls for the CcLdmium pigment
particuiate found at these sources.
5.4.3 Emissions
•
Emission factors are not available for pigment blending
operations, which have not been recognized as a potential source
of cadmium emissions in previous surveys. No test data are
available that can be used to calculate emission factors.
5-22
-------
SECTION'S
EMISSIONS FROM COMBUSTION SOURCES
Cadmium is often found as a trace contaminant in fossil
fuels or waste materials. When these materials are fed to
combustion processes, the combination of the elevated temperature
of the process and the relative volatility of cadmium results in
cadmium being partitioned between the ash and the combustion gas
exhaust stream. This section addresses cadmium emissions from
seven stationary source combustion processes:
- Coal combustion
- Oil combustion
- Natural gas combustion
- Wood combustion
- Municipal waste combustion
- Sewage sludge incineration
- Medical waste incineration
These seven processes fall into two general categories. The
first four involve fossil fuel combustion for energy, steam, and
heat generation, while the last three are primarily waste
disposal processes, although some energy may be recovered from
these processes. The paragraphs below provide a general
introduction to the two combustion categories. As. part of this
introduction, a summary of nationwide fuel usage is presented in
detail. This information was used in Section 3 to develop
nationwide emissions of cadmium for different sectors and fuels.
Such information is also needed to develop cadmium emission
inventories for specific areas. _It is included in the
6-1
-------
introduction rather than in individual sections because (1) the
individual sections are organized by fuel type rather than by use
sector and (2) fossil fuel use patterns differ geographically by
industry sector. The introduction also briefly describes the
waste combustion category. Specific discussions for the seven
source categories follow these introductory paragraphs.
In 1990, the total annual nationwide energy consumption in
the United States was 85.533 x 1012 megajoules (MJ)
(81.151 x 1015 British thermal units [Btu]).38 Of this total
about 52.011 x 10" MJ (49.347 x 1015 Btu) Qr 61 percent ^^
consumption of coal, petroleum products, and natural gas in
nontransportation combustion processes. (No data were available
on energy consumption for wood combustion from the United States
Department of Energy.) Table 6-1 summarizes the 1990 United
States distribution of fossil fuel combustion as a function of
fuel in the utility, industrial, commercial, and residential
sectors. The paragraphs below provide brief summaries of fuel
use patterns; additional details on fuel consumption by sector
for each State can be found in Reference 38.
As shown in Table 6-1, the utility sector is the largest
fossil fuel energy consumer at the rate of 21.290 x 1012 MJ
(20.199 x 1015 Btu) per year. About 80 percent of this energy
was generated from coal combustion, with bituminous and lignite
coal contributing substantially greater quantities than
anthracite coal, in fact, Pennsylvania is the only State in
which anthracite coal is used for electric power generation.
Although most States rely primarily on coal for power generation
the distribution among fossil fuels varies from State to State
and several states rely heavily on.natural gas and fuel oil for
power generation, in California, natural gas provides about
90 percent of the fossil-fuel based electricity production, and
no coal is used. In Hawaii, fueloil is used exclusively, while
6-2
-------
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6-3
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in Oklahoma and Texas, a mixture of coal and fuel oil are used.
In Florida, Louisiana, Massachusetts, and New York, coal, fuel
oil, and natural gas each represent a substantial fraction of the
power generation. The States of Idaho, Maine, Rhode Island,, and
Vermont had no coal consumption. Idaho relies exclusively on
hydroelectric power, while the New England States use a mixture
of -fuel oil, natural gas, nuclear, and hydroelectric 'sources.
At 20.591 x 1012 MJ (19.537 x 1015 Btu) per year, the
industrial sector is the second largest consumer of fossil fuels.
This sector uses a mixture of natural gas (43 percent), fuel oil
(8 percent), other petroleum fuels (34 percent), and coal
(14 percent). The other petroleum fuels that are used include
primarily liquified petroleum gas, asphalt and road oil, and
other nonclassified fuels. Again, the.distribution among the
three fuel types varies substantially from State to State, with
each of the three contributing significant fractions in most
States. Notable exceptions are Hawaii, which relies almost
exclusively on petroleum fuels; Alaska, which relies primarily on
natural gas; and the northeastern States'of Connecticut, New
Hampshire, Rhode Island, and Vermont, which use almost no coal.
As shown in Table 6-1, substantially smaller quantities of
fossil fuel are used in the commercial and residential sectors
than are used in the utility and industrial sectors. The fuels
used are primarily natural gas, fuel oil, and liquified petroleum
gas (the "other petroleum fuels" in the residential category).
Almost all States use a mixture of the fuels, but the
distributions vary substantially, with some States like
California and Louisiana using primarily natural gas and others
like New Hampshire and Vermont using a much greater fraction of
fuel oil. One unique case is Pennsylvania where anthracite coal
is used in both the residential and commercial sectors.
6-4
-------
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in Oklahoma and Texas, a mixture of coal and fuel oil are used.
In Florida, Louisiana, Massachusetts, and New York, coal, fuel
oil, and natural gas each represent a substantial fraction of the
power generation. The States of Idaho, Maine, Rhode Island, and
Vermont had no coal consumption. Idaho relies exclusively on
hydroelectric power, while the New England States use a mixture
of fuel oil, natural gas, nuclear, and hydroelectric- sources.
At 20.591 x 10?-2 MJ (19.537 x 101S Btu) per year, the
industrial sector is the second-largest consumer of fossil fuels.
This sector uses a mixture of natural gas (43 percent), fuel oil
(8 percent), other petroleum fuels (34 percent), and coal
(14 percent). The other petroleum fuels that are used include
primarily liquified petroleum gas, asphalt and road oil, and
other nonclassified fuels. Again, the.distribution among the
three fuel types varies substantially from, State to State, with
each of the three contributing significant fractions in most
States. Notable exceptions are Hawaii, which relies almost
exclusively on petroleum fuels; Alaska, which relies primarily on
natural gas; and the northeastern States'of Connecticut, New
Hampshire, Rhode Island, and Vermont, which use almost no coal.
As shown in Table 6-1, substantially smaller quantities of
fossil fuel are used in the commercial and residential sectors
than are.used in the utility and industrial sectors. The fuels
used are primarily natural gas, fuel oil, .and liquified petroleum
gas (the "other petroleum fuels" in the residential category).
Almost all States use a mixture of the fuels, but the
distributions vary substantially, with some States like
California and Louisiana using primarily natural gas and others
like New Hampshire and Vermont using a much greater fraction of
fuel oil. One unique case is Pennsylvania where 'anthracite coal
is used in both the residential and commercial sectors.
6-4
-------
In the individual sections below, additional information
will be presented on the cadmium content of the different fuels
and on the relationship between fuel type and emissions.
However, for any geographic area, the contribution of energy
.generation sources to cadmium emissions will be a function of the
distribution of fuels used in the different sectors within the
area. • ' • - • . • •
The sources within the second combustion category are
engaged primarily in waste disposal. Cadmium emissions from
these processes are related to the cadmium levels in the waste.
The different waste types are generally characterized with
distinct source categories. Furthermore, these waste disposal
practices are not strongly related. Consequently, each of these
categories will be characterized individually within the sections
below rather than in a general discussion here. The eight
sections below-have a consistent organization. First, the
characteristics of the fuel, or waste are described and, in the
' case of the waste combustion processes, the general source
category is also described. Second, process descriptions are
presented and emission points are identified. Third, available
emission control measures are identified and described. Finally,
emission factors are presented. A discussion of the sampling and
analytical methods used to determine the cadmium emission levels
from combustion sources is presented in Section 9.
6.1 COAL COMBUSTION
As presented in Table 6-1, most coal combustion in the
United States occurs in the utility and industrial sectors, with '
about 85 percent being bituminous and lignite combustion within
the utility'sector"and about 14 percent being bituminous and '
lignite combustion in the industrial sector. Consequently, the
focus of the discussion below will be on bituminous and lignite
6-5
-------
coal combustion in utility and industrial boilers. However,
limited information on anthracite coal combustion will also be
presented.
6'1-1 Coal
The coal characteristics of greatest interest in evaluating
cadmium emissions from coal combustion are coal heating values
and coal cadmium content. Cadmium emissions are a direct
function of the cadmium content, while heating values are used to
convert emission factors between mass input -based and heat
input-based activity levels. This section briefly summarizes the
information about coal heating levels and cadmium content
contained in References 39 through 41. More complete summaries
can be found in Reference 39, "and detailed analyses of coal
cadmium content as a function of coal type and geographic region
can be found in References 40 and 41.
Coal is a complex combination of organic matter and
inorganic ash formed in geologic formations from successive
layers of fallen vegetation and other organic matter. Coal types
are broadly classified as anthracite, bituminous, subbituminous,
or lignite, and classification is made by heating values and
amounts of fixed carbon, volatile matter, ash, sulfur, and
moisture.42 Formulas for differentiating coals based on these
properties are given in Reference 43. These four coal types are
further subdivided into 13 component groups. Table 6-2
summarizes information about the heating values for these
component groups . ^ ^
The heating value of coal varies between coal regions,
between mines within a region, between seams within a mine, and
within, a seam. The variability is" minimal compared to that found
? ................. d?s«i^d ...... below, but^ ..... aay._be.,_,,important.;.,,
6-6
-------
TABLE 6-2. COAL HEATING VALUES
Coal class
Anthracite
Bituminous
=====
Component
group
A1
A2
A3
81
B2
83
84
B5
SI
S2
S3
L1
L2
==^
Definition
Meta-anthracJte
Anthracite
Semianthracite
Low volatile
bituminous
Medium volatile
bituminous
High volatile
A bituminous
High volatile
I bituminous
High volatile
! bituminous
Subbrtuminous A
Subbituminous B
Subbrtuminous C
Lignrte A
Lignite B
=====
Source3
PA.RI
CO,PA,NM
AR.PA.VA
AR,MD,OK,PA,
WV
AL,PA,VA
AL,CO,KS,KY,
MO,NM,PA,
TN,TX,UT,VA,
WV
L,KY,MO,OH,
UT,WY
L,IN,IA,MI
MT.WA
WY
CO.WY
ND.TX
NA
Heating value, kJ/kg (Btu/lb)
21,580-29,530
(9,310-12,740)
27,700-31,800
(11,950-13,720)
27,460-31,750
(11,850-13,700)
30,640-34,140
(13,220-14,730)
31,360-33,170
(13,530-14,310)
28,340-35,710
(12,230-14,510)
26,190-30-480
(11,300-13,150)
24,450-27,490
(10,550-11,860)
23,940-25,820
(10,330-11,140)
21,650-22,270
(9,340-9,610)
19,280-19,890
(8,320-8,580)
16,130-17,030
(6,960-7,350)
NA
25,560
(1 1 ,030)
30,270
(13,001)
29,800
(12,860)
32,400
(13,980)
32,170
(13,880)
31,170
(13,450)
28,480
(1 2,290)
26,030
(11,230)
24,890
(10,740)
21,970
(9,480)
19,580
(8,450)
16,660
(7,190)
NA
Source: Reference 39.
aNA = Not available.
6-7
-------
when fuel heat content is used as the activity level, measure for
source emission calculations. Data presented in Table 6-3
illustrate the regional variability of coal heat content. Heat
content among coals from several different mines within a region
appears to exhibit greater variability than either variability
within a mine or within a seam. For the sample'points presented
,in Table 6-3, intermine variability averaged 15 percent,
intramine variability 7 percent, and intraseam variability
3 percent. Because few combustion sources burn coal from just
one seam or one mine, coal heat content variability may
significantly affect emission estimates that are being calculated
using emission factors, coal use data, and coal heat content
data, even if the source gets all its coal from the same area of
the country.^ ^
To an even greater extent than the heating value, the
cadmium content of coal varies substantially among coal types, at
different locations in the same mine, and across geographic
regions. The most comprehensive source of information on coal
composition is the United States Geological Survey (USGS)
National Coal Resources Data System (NCRDS). Geochemical and
trace element data are stored within the USCHEM file of NCRDS.
As of October 1982, the file contained information on 7,533 coal
samples representing all United States coal provinces. Trace
element analysis for about 4,400 coal samples were included in
the data base. This computerized data system was not accessed
during the current study due to time and budgetary constraints
and information from"USGS that indicated that few data had been
added to the system since 1972; however, a summary of the-data
presented in Reference 39 was reviewed. The most extensive
source of published trace element data was produced by.Swanson
et al. of the USGS.41 This report contains data for 799 coal
samples taken from ISO producing mines and includes the most- :.'
ijnportant Jtaited' States coal seams. Data from the Swanson study
6-8'
-------
H
1
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was the initial input 'into the USCHEM file of NCRDS. The
information presented here summarizes Brooks' review of the
results published by White and Swanson.39'4! Note that these
results are consistent with unpublished analyses conducted by
USGS on the data contained in NCRDS as of 1989.44 More
information on the sampling and analysis of cadmium in coal is
presented 'j!h Section 9. . - .
Table 6-4 presents information on the mean concentration of
cadmium in coal and on the distributions of cadmium
concentrations by coal type. Bituminous coals have the highest
mean cadmium concentration, 0.91 parts per million by
weight (ppmwt). The standard deviation of the mean, 7.3 ppmwt,
exceeds the mean, .indicating substantial variation within the
data. Bituminous coals have the greatest reported range of
cadmium concentrations (<0.02 to 100 ppmwt).39 Based on
conversations with USGS personnel, the means reported in
Table 6-4 are regarded as typical values for in-ground cadmium
concentration in coals in the United States.
The concentration of cadmium in coal also varies by
geographic region from which the coal is mined. Based on the
"best typical" values for each region, which are footnoted in
Table 6-5, coals from the Interior Province have the highest mean
cadmium concentration, 5.47 ppmwt. That study also showed-that
the greatest range of concentrations is found in coals from the
Interior Province, with a reported range of <0.02 to 100 ppmwt.
Also, based on the best-available data, the lowest mean
concentration is found in coals from the Appalachian region
(0.13 ppmwt),39 The means reported in Table 6-5 may be regarded
as typical in-ground concentrations of cadmium in coals from each
geographic region.
6-10
-------
TABLE 6-4. CADMIUM CONCENTRATION IN COAL BY COAL TYPE
Coal type
Bituminous
Subbituminous
Anthracite
Lignite
No. of samples
3,527
640
52
183
Cadmium concentration, ppmwt
Range
<0.02 to 100
0.04 to 3.7
0.1 to 0.3
<0.1t to 5.5
Arithmetic
0.91
0.38
0.22
• 0.55
Standard
7.3
0.47
0.30
0.61
1
Source: Reference 39.
TABLE 6-5. CADMIUM CONCENTRATION IN COAL BY REGION
Region
Appalachian
Interior
Illinois Basin c
Gulf Province
Rocky Mountains
No. of
samples
2,749
331
592
155
82
38
34
371
490
512
124
107
18
Cadmium concentration, ppmwt
Range
0.03-6.8
<0.02-100
0.1-65
<0.11-5.5
0.02-2.7
<0.03-0.5
<0.1-0.7
=======5=i
Arithmetic mean
0.1 3a
0.7b
5.47a
7.1b
2.89
0.50?
1.3°
0.30a
0.08
• 0.35a
<0.5b
0.28a
<0.2b
========1
Standard deviation
0.21 .
18.5
0.49
0.48
0.38
0.59
Source: Reference 39.
™ "' studv,are ,based on the most comprehensive data set currently available (the
and may be used as typical values for cadmium in coal from these regions.
h * *' **"? are '?duded in *e NCRDS. Arithmetic means from the entire NCRDS
" m ™ ?"* Studv' since ** NCRDS COT«™s many more coal samples.
°f Va'UeS f°r Cadmium content in individual
cEastem section of Interior Province.
6-11
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6.1.2 Process Dsacri^-ior.39,42,45
As shown in Table 6-1, almost all coal combustion occurs in
utility arid industrial boilers. Almost all of the coal burned is
bituminous and subbituminous (95 percent) and lignite
(4 percent).39 However, the processes used for the different
coals are comparable. ' The paragraphs'below first describe the
boilers used for bituminous coal combustion. Then, lignite and
anthracite combustion are described briefly. References 42 and
45 offer additional details on these processes.
The two major coal combustion techniques used to fire
bituminous and subbituminous coals are suspension firing and
grate firing. Suspension firing is the primary combustion
mechanism in pulverized coal and cyclone systems. Grate firing -
is the primary mechanism in underfeed and .overfeed stokers. Both
mechanisms are employed in spreader stokers.
Pulverized coal furnaces are used primarily in utility and '
large industrial boilers. In these systems, the coal is
pulverized in a mill to the consistency of talcum power (i.e., at:
least 70 percent of the particles will pass through a 200-mesh
sieve). The pulverized coal is generally entrained in primary
air and suspension-fired through the burners to the combustion
chamber. Pulverized coal furnaces are classified as either dry
or wet bottom, depending on the ash removal technique. Dry
bottom furnaces fire coals with high ash fusion temperatures, and
dry ash removal techniques are used, in wet bottom (slag tap)
furnaces, coals with low ash fusion temperatures are used; and
molten ash is drained from the bottom of the furnace.
Cyclone furnaces burn low ash fusion temperature-coal
crushed to a 4-mesh size. The coal is fed tangentially, with
primary air, to a horizontal cylindrical combustion chamber.
€-12
-------
Small coal particles are burned in suspension, while the larger
particles are forced against the outer wall. Because of the high
temperatures developed in the relatively small furnace volume,
and because of the low fusion temperature of the coal ash, much
of the ash forms a.liquid slag that is drained from the bottom of
the furnace through a slag tap opening. Cyclone furnaces are
used mostly in utility' and large 'industrial applications.
In spreader stokers, a flipping mechanism throws the coal
into the furnace and onto a moving grate. Combustion occurs
partially in suspension and partially on the grate. Because the
entrained particles in the furnace exhaust have substantial
carbon, fly ash reinjection from mechanical collectors is
commonly used to improve boiler efficiency. Ash residue in the
fuel bed is deposited in a receiving pit at the end of the grate:
In overfeed stokers, coal is fed onto a traveling or
vibrating grate and burns on the fuel bed as it progresses
through the furnace. Ash particles fall into an ash pit at the
rear of the stoker. ."Overfeed" applies because the coal is fed
onto the moving grate under an adjustable gate. Conversely, in
"underfeed" stokers, coal is fed upward into the firing zone by
mechanical rams of screw conveyers. The coal moves in a channel,
known as a retort, from which it is forced upward, spilling over
the top of each side to feed the fuel bed. Combustion is
completed by the time the bed reaches the side dump grates, from
which the ash is discharged to shallow pits.
The next most, common coal used in the United States is
lignite. Lignite is a relatively young coal with properties
intermediate to those of bituminous coal and peat. Because
lignite has a high moisture content (35 to 40 weight percent) and
a low wet basis heating value (16,660 kJ/kg [7,190 Btu/lb]), it
-Srenerally_is ss_ed_as_. a_fuel_..only, in areas- in- .which,-it-is- mined,.
6-13
-------
Lignite is used mainly for steam/electric: production in power
plants and typically is fired in larger pulverized coal-fired or
cyclone-fired boilers.
Anthracite coal is a high-rank coal with more fixed carbon
and less volatile matter than either bituminous coal or lignite.
Because of its low volatile matter content and slight clinkering,
anthracite is most commonly fired in medium-sized traveling grate
stokers and small, hand-fired units. Some anthracite
(occasionally with petroleum coke) is used in pulverized coal-
fired boilers, and it may be blended with'bituminous coal.
Because of its low sulfur content (typically .less than 0.8 weight
percent) and minimal smoking tendencies, anthracite is considered
a desirable fuel in areas where it is readily available. In the
. United States, anthracite is mined in northeastern Pennsylvania .
and is consumed mostly in Pennsylvania and surrounding States.
The la-rgest use of anthracite is for space heating. Lesser
amounts are employed for steam/electric production, typically in
underfeed stoker and pulverized coal dry-bottom boilers.
Although small quantities of cadmium may be emitted as
fugitive particulate matter from coal storage and handling
operations, the primary source of cadmium emissions from coal
combustion is the combustion stack. Because the combustion zone '
in boilers operates at temperatures in "excess of 1100°C (2000°F),
the cadmium in the coal is volatilized. As the flue gas cools in
the convective heat transfer section and further in the air
preheater, the volatilized cadmium condenses. The cadmium may
condense 9r adsorb onto existing particles according to the
available surface area or it may condense homogeneously, forming
fine particles. The cadmium thus volatilized would be depleted •
in the bottom ash and concentrated in the fly ash since the fly
ash has more relative surface area than the bottom ash and since
the bottom ash does not come in contact with the volatilized
. •|ICTj|lJirB||l.t |i:i II^U, Illlll IB||I jlllj HU|Ji| |lij.iljiinllillll III •NUN III 111
6-14
-------
cadmium long enough for the cadmium to condense on the bottom
ash.
6.1.3 Emission Control, Measures42
Data on the performance of coal combustion emission control
measures, relative to cadmium, are quite sparse. Furthermore,
many of the data that are available are somewhat dated and are of
questionable reliability.
Emission control measures for coal-fired boilers include
controls based on combustor design and operating practices that
are directed primarily at nitrogen oxides (NOX) and particulate
matter (PM) control and add-on air pollution control devices that
are designed for acid gas and PM control. Those measures that -.
are most likely to affect cadmium control are add-on control
systems designed for both PM and acid gas control. The primary
types of PM control devices used for coal combustion include
multiple cyclones, electrostatic precipitators, fabric filters
(baghouses), and wet scrubbers, while both wet and dry flue gas
desulfurization (FGD) systems are used for sulfur dioxide (S02).
Some measure of PM control is also obtained from ash settling in
boiler/air heater/economizer dust hoppers, large breeches, and
chimney bases, but these mechanisms will not significantly reduce
cadmium emissions.
Electrostatic precipitators (ESP) are the most common high
efficiency control device used on pulverized coal and cyclone
units. These devices are also being used increasingly on
stokers. Generally, PM collection efficiencies are a function of
the.specific collection area'(i.e., the ratio of the collection
plate area to the volumetric flow rate of flue gas through the
device), and PM efficiencies of"99.9 weight percent have been
measured with ESP's. Fabric filters have recently.. seen increased
6-15
-------
use in both utility and industrial applications both as a PM
control measure and as the collection mechanism in dry FGD
systems, generally effecting about 99.8 percent PM control. Wet
scrubbers are also used to control PM emissions, although their
primary use is to control emissions of sulfur oxides. Because,
unlike the other PM control devices, wet scrubbers reduce- the gas
stream temperature, -they may be more effective than the other
controls in removing condensible PM, such as cadmium. The other
PM control devices would require some type of acid gas control,
such as a spray dryer.
Mechanical collectors, generally multiple cyclones, are the
primary means of control on many stokers and are sometimes
installed upstream of high efficiency control devices in order to
reduce the ash collection burden. Depending on application and •
design, multiple cyclone PM-efficiencies can vary tremendously.
However, these systems are relatively inefficient for fine
particles and are not likely to'provide measurable control of
cadmium emissions, which are primarily in the fine particle
fractions of the exhaust.
The section on emission factors below presents the available
data on emission control system performance. However, in
evaluating the potential emissions from a facility or group of
facilities, any assumptions about control system performance,
including those based on the data presenteid herein, should be
examined carefully to assure that they are supported by reliable
test data obtained via methods comparable to those described in
Section 9. Also, performance estimates must be consistent with
the physical and chemical properties of the compounds being
emitted and with the operating characteristics of the systems
being evaluated.
6-16
-------
6.1.4 Emission^
The primary source of cadmium emissions from coal combustion
- operations is the combustion gas exhaust stack. Small amounts of
cadmium also may be emitted as a component of the fugitive PM
emissions from coal and ash handling.
Two distinct sources of information were used to develop and
evaluate cadmium emission .factors for coal combustion. A third
source was considered but was not used. First, the data
.presented above on cadmium concentrations in coal and coal
heating values were, used to develop mass balance-based emission
factors under the conservative assumption that all cadmium
charged with the coal is emitted as-fine PM in the stack gas.
The assumption is based on a lack of data on the effectiveness of
cadmium controls for coal combustion. Second, the emission
factors presented in the Coal and Oil Locating and Estimating
(L&E) document were reviewed and summarized.39 No attempt was
made to verify the sources of data used in the coal and oil L&E
document or to rate the emission factors that were developed
therein. The results obtained from each of the these methods are
discussed separately in the paragraphs below.' Then the relative
merits of the emission factors obtained by the different methods
are examined, and the best typical emission factors are
identified. The third approach, using controlled emission
factors from a summary of the PISCES literature data base, was
considered, but those results are based -on a much smaller number
of data points. Data were excluded as unreliable for a variety
of reasons, including uncharacteristically low ESP control
efficiencies, but the variability in the data did not improve
significantly;46
The information presented in the literature indicates that
virtually all of the cadmium contained in .the.coal., is emitted
6-17
-------
from the furnace as fine PM. Consequently, the coal heating
values presented in Table 6-2 and the coal cadmium concentrations
presented in Table 6-4 can be used to develop emission factors
for major coal'types under the conservative assumption that all
cadmium in the coal is emitted. Furthermore, nqte that the coal
composition data in Table 6-2 are based on "in-ground cadmium
concentrations. The, calculated emission factors shown in
Table 6-6 are based on the conservative assumption that as-fired
coal contains equivalent concentrations. If cadmium
concentrations are reduced during coal cleaning operations, these
estimates will be biased high. The Utility Air Regulatory Group
(UARG) and the Electric Power Research Institute (EPRI) are
working with the USGS to compile data on the extent of coal
washing in the United States and its effects on the trace metal •
content of coal. This study is expected to be completed by the •
end of 1993. Preliminary data from.the United States Department
of Energy indicates that there is reduction in cadmium
concentrations (25 to 50 percent) from coal cleaning.47 The
cadmium emission factors derived from these reduced cadmium
concentrations are also shown in Table 6-6.
A comprehensive summary of the test data generated prior to
1989 for coal-fired boilers and furnaces was presented in
Reference 39. The data from individual tests that were presented
in that report are compiled in Table B-l in Appendix B.
Table 6-7 summarizes these data as a function of coal type and
control status. Note the wide range of emission factors for each
coal type, in addition to the variability in coal heat content
and the uncertainty in cadmium sampling and analysis, this range
reflects, the substantial variation in coal cadmium content and
highlights the need to obtain coal-specific cadmium data to
calculate emission estimates whenever possible. Also note that
the data are combined across industry sector and boiler type •
6-18
-------
TABLE 6-6. CALCULATED UNCONTROLLED CADMIUM EMISSION FACTORS
FOR COAL COMBUSTION
Coal type
Bituminous13
Subbituminous0
Anthracite^
Lignite6
kg/1015J
30 (15-23)
17 (8.6-13)
7.3 (3.6-5.5)
33 (17-25)
Calculated cadmium emission factors3
lb/1012Btu
70 (35-53)
40 (20-30)
17 (8.4-13)
76 (38-57)
g/Mg coal
-. 0.91--
(0.46-0.68)
0.38
(0.19-0.28)
0.22
(0.11-0.16)
0.55
(0.28-0.41 )
1 0"3 !b/ton coal
1.8
(0.91-1.36)
0.76
(0.38-0.57)
0.44
(0.22-0.33)
1.1
(0.55-0.82)
aValues in parentheses are based on a 25 to 50 percent reduction in cadmium concentrations from
coal cleaning.
Based on arithmetic average of the five average heating values in Table 6-2.
GBased on arithmetic average of the three average heating values in Table 6-2.
Based on average heating value for coal category A2 in Table 6-2.
eBased on average heating value for coal category L1 in Table 6-2.
because these parameters are not expected to have a substantial
effect on emission factors.
The available test data on cadmium emission control, which
are presented in Reference 39, are quite limited. Except for the
ESP, control efficiencies are based on only a few data points
and, therefore, may not be very reliable. According to'
Reference 39, an average of 75 percent control of cadmium
emissions has been found for ESP's based on 21 data points for
eight boilers. Control levels ranged from about 20 percent to
99.7 percent. The control efficiencies may or may not be
6-19
-------
6-20
-------
indicative of the long-term performance of ESP's on cadmium
emissions from combustion sources. With a conservative.
assumption of 75 .percent control by ESP's, at least 75 percent
control should-be achieved by a combination of an ESP and a wet
scrubber or by two ESP's in series. Insufficient data are
available on the performance of wet scrubbers relative to cadmium
emissions; but,.according to the literature, wet scrubbers can
achieve over 99 percent removal of PM. Cadmium reduction with a
wet scrubber is expected to be less than .that since cadmium
partitions with the fine PM, and wet scrubbers are much less
effective in reducing emissions of fine PM.48 A conservative.
estimate of cadmium reduction with a wet scrubber would be
75 percent since PM control with a scrubber is at least as good
as PM control with an ESP system. The reported 29 percent
control achieved by multiclones is consistent with the
inefficiency of these systems in reducing cadmium emissions.
Based on review of the available data, the best estimates
for uncontrolled emission factors for typical coal combustion
facilities are those obtained from a mass balance using coal
composition data. This approach was selected because the
available test data are of uncertain quality, and the coal
concentration data are representative of a much larger industry
segment. Controlled emission factors were obtained by applying
the conservative 75 percent control for ESP's, greater than
75 percent control for a combination of ESP's and wet scrubbers,
and greater than 75 percent control for two ESP's in series.
Data were inadequate to estimate efficiencies for systems
equipped with mechanical collectors, wet scrubbers, or fabric
filters. The resultant best typical emission factors are shown
in Table 6-8.
6-21
-------
TABLE 6-8. BEST TYPICAL CADMIUM EMISSION FACTORS FOR COAL COMBUSTION
Typical cadmium emission factors
^arnrni i i
Coal type3
status1
g/Mg coal
10'3 Ib/ton
30
ESP
7.6
ESP/wet scrubber
<7.6
ESP-2 stage
<7.6
0.91
0.23
<0.23
1.8
0.46
<0.46
A
A
A
A
Uncontrolled
ESP
ESP/wet scrubber
ESP-2 stage
7.3
1.8
<1.8
-------
The ESP-controlled emission factors for bituminous,
subbituminous, and lignite coal were compared with the median and
mean ESP-controlled emission factors summarized from the PISCES
data base.46 For each coal type, the emission factors for
cadmium presented in this L&E were higher than those from PISCES
by more than an order of magnitude. However, the PISCES results
are based on a much smaller number of' samples due to the
exclusion of data considered unreliable. The variability in the
PISCES data was not improved significantly with the .exclusion.
The cadmium emission factors presented in this L&E for coal
combustion should be viewed as the most realistic nationwide
estimates possible, based on what little data are available. 'It
should be recognized that, as with the PISCES data, there is
considerable uncertainty in these estimates. The uncertainty in.
the L&E estimates is due to the wide variability in cadmium
concentrations in coal, the variability in coal heat content, and
the uncertainty in sampling and analytical methodologies for .
detecting cadmium. Therefore, these estimates should not be used
to determine emissions from specific coal combustion facilities.
6.2 FUEL OIL COMBUSTION
As shown in Table 6-1, based on energy consumption estimates
by the U. S. Department of Energy, fuel oil use spans the four
sectors of energy users. Distillate fuel oil is used extensively
in all sectors with the largest use in the utility (31 percent)
and the industrial (32 percent) sectors, but with substantial
amounts used in both the commercial (13 percent) and residential
(23 percent) sectors. Residual oil is used primarily in the
industrial (56 percent) and commercial , (33 percent) sectors. '
Because the oil combustion process is not complex, and control
. systems are not widely applied to oil-fired units, the discussion
6-23
-------
below will focus on fuel oil characteristics and on emissions
from oil-fired units.38
6.2.1 Fuel Oil Characteristics39
The fuel oil characteristics of greatest importance for
characterizing cadmium emissions from fuel oil combustion are"the
heating value and the cadmium content of the oil. The heating
value is used for converting from emission .factors with mass- or
volume-based activity levels to those with activity levels based
on heat input.
The term fuel oil covers a variety of petroleum products,
including crude petroleum, lighter petroleum.fractions such as
kerosene, and heavier residual fractions left after distillation;
To provide standardization and means for comparison,
specifications have been established that separate fuel oils into
various grades. Fuel oils are graded according to specific
gravity and viscosity, with No. 1 Grade being the lightest and
No. 6 the heaviest. The heating value of fuel oils is expressed.
in terms of kJ/L (Btu/gal) of oil at 16°C (60°F) or kJ/kg
(Btu/lb) of oil. The heating value per gallon increases with
specific gravity because there is more weight per gallon. The
heating value per mass of oil varies inversely with specific
gravity because lighter oil contains more hydrogen. For an
uncracked distillate or residual oil, heating value can be
approximated, by the following equation:
Btu/lb - 17,660 + (69 x API gravity)
For a cracked distillate, the relationship becomes: '
Btu/lb - 17,780 + (54 x API gravity)
6-24
-------
Table 6-9 provides an overall summary of the heating values
of typical fuel oils used in the United States, and Table 6-10
shows the variability in fuel oil heating values used in various
regions of the"country. Appendix B of Reference 39 provides
.additional details.
The data base for cadmium content in fuel oils is much more
limited than was the coal cadmium content data base. A number of
petroleum industry associations were contacted, but none who
reported have done any research on metals content in fuel oils.
No single centralized data base is available, and the information
presented below is based on limited data from individual studies.
. Concentrations of cadmium in fuel oil depend upon the type
of oil used. No comprehensive oil characterization studies have-
been done, but data in the literature report similar cadmium
concentration means and ranges in residual and distillate oils.
The suggested typical cadmium content of residual oil is
0.30 ppmwt, while that of distillate oil is 0.21 ppmwt. The
typical value for cadmium in crude oil is 0.03 ppmwt. Table 6-11
lists the typical values for cadmium in oils. The typical values
for distillate and crude oil were obtained by taking the average
of the mean values found in the literature. The value for
residual oil was based on reported concentrations without using
the two high values of 2.27 and 2.02 ppmwt.
6-2.2 Process Descript-.iqri42 ' 45
Fuel oils are broadly classified into two" major types:
distillate and residual. Distillate oils (fuel oil grade
Nos.•l and 2) are more volatile and less viscous than residual
oils, having negligible ash and nitrogen contents and usually
containing less than 0.1 weight"percent sulfur. No. 4 residual
AS sometimes classified as , a ..distillate;. NgJ_.S .i.s_. sometimes
6-25
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TABLE 6-11. CADMIUM CONCENTRATION IN OIL BY OIL TYPE
Fuel oil type
Residual No. 6
Distillate No. 2
Crude
No. of
samples
19
4
-
Cadmium concentration, ppmwt
Range
0.010-2.3
0:OTO-0.95
0.010-0.05
Typical value
0.30a
0.21 b
0.030°
Source: Reference 39.
a
Based on reported concentrations without using the two high values, 2.3 and 2.0 ppmwt.
° Average of two studies.
GAveraga of three studies of foreign and domestic crude oils. Number of samples not given.
referred to as Bunker c. Being more viscous and less volatile
than distillate oils, the heavier residual oils (Nos. 5 and 6)
must be heated to facilitate handling and proper atomization.
Because residual oils are produced from the residue after lighter
fractions (gasoline, kerosene, and distillate oils) have been
removed from the crude oil, they contain significant quantities
of ash, nitrogen, and sulfur. Small amounts of crude are
sometimes burned for enhanced oil recovery or for refinery-
operations .
i. . '! ' :
Oil-fired boilers and furnaces are simpler and have much
less variation in design than the coal-fired systems described
earlier. The primary components of the system are the burner,
which atomizes the fuel and introduces it along with the
combustion air into the flame, and the furnace, which provides
the residence time and mixing needed to complete combustion of
the fuel. The primary difference in systems that fire distillate
oil and residual oil is that the residual oil systems must have
6-28
-------
an oil preheater to reduce the viscosity of the oil so that it
can be atomized properly in the burner. Systems that fire
distillate oil and residual oil also have different atomization
methods.
The only source of cadmium emissions from oil-fired boilers
and furnaces' is the'combustion stack. Because the entire fuel
supply is exposed to high flame temperatures, essentially all of
the cadmium contained in the fuel oil will be volatilized, with
most condensing onto small particles and then exit the furnace
with the combustion gases. Unless these combustion gases are
exposed to low-temperature air pollution control systems and
high-efficiency PM control systems, which typically are not found
on oil-fired units, the cadmium will be exhausted as fine PM
through the combustion stack.
6.2.3 Emission Control Measures39/45
The three types of control measures applied to oil-fired '
boilers and furnaces are boiler modifications, fuel substitution,
and flue gas cleaning systems. Only fuel substitution and flue
gas cleaning systems will affect cadmium emissions. Fuel
substitution is used primarily to reduce SO2 and NOX emissions.
However, if the substituted fuels- have lower cadmium
concentrations, the substitution will also reduce cadmium
emissions. Because PM emissions from oil-fired units are
generally much lower than those from coal-fired units,
high-efficiency PM control systems are generally not employed on
oil-fired systems. Consequently, these flue gas cleaning systems
are not likely to achieve substantial cadmium control. However,
the flue gas systems that are used on oil-fired units are
described briefly below.
6-29
-------
Flue gas cleaning equipment generally is employed only on
larger oil-fired boilers. Mechanical collectors, a prevalent
type of control device, are primarily useful in controlling PM
generated during -soot-blowing, during upset conditions, or when a
very dirty heavy oil is fired. During these situations, high
efficiency cyclonic collectors can affect up to 85 percent
control of PM, but 'less control of cadmium is expected with
mechanical collectors because cadmium is enriched onto fine PM
which is not as easily captured by these control devices.
Electrostatic precipitators are commonly used in oil-fired
power plants. Older ESP's may remove 40 to 60 percent of the PM
but lower cadmium control is expected beca.use of the reason cited
above. Newer ESP's may remove even more, but no data are
available for oil-fired power plants. Scrubbing systems have
been installed on oil-fired boilers to control both sulfur oxides
and PM. Similar to systems applied to coal combustion
(presented in Reference 39), these systems can achieve PM control
efficiencies of 50 to 90 percent. Because they provide gas
cooling below the condensation point of cadmium, some cadmium
control may be obtained, but no data are available on their
performance.
6.2.4 Emisgionei
^ The only substantive source of cadmium emissions from fuel
oil combustion operations is the combustion gas exhaust stack
Three types of information were used to develop emission factors
for oil combustion. First, the data described above on fuel oil
heating value and cadmium content of fuel oils were used to
develop emission factors by mass balance, assuming conservatively
that all cadmium fired with the fuel oil is emitted, through the
stack, second, the emission factors from the coal and oil L&E
document were evaluated and summarized, but no, attempt was made
6-30
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to verify original references or to rate these data. Finally,
rated emission test data developed in preparation of this
document were evaluated and summarized. The paragraphs below
first present the results generated from each of the three
sources. Then, the relative merits of the emission factors
generated via each of the procedures are discussed, and the best
."typical" emission factors are identified. . • - •
The literature on fuel oil combustion suggests that
essentially all cadmium in the fuel oil is volatilized in the
combustion zone, with most condensing onto small particles and
exhausted as fine PM in the combustion gas stream. Using the
assumption that 100 percent of the cadmium in fuel oil leaves the
boiler or furnace in the exhaust gases, the data in Tables 6-9
and 6-11 can be used to calculate uncontrolled emission factors ..
for No. 2 distillate and No. 6 residual oil. Data presented in
Reference 45, which show an average crude oil heating value of
42,500 kJ/kg (18,300 Btu/lb) and .41,300 kJ/L (148,000 Btu/gal),
can be combined with the cadmium content data in Table 6-11 to
calculate uncontrolled emission factors for crude oil combustion.
The results of these calculations are presented in Table 6-12.
A comprehensive summary-of the emission data generated prior
to 1989 was prepared by Brooks.39 These somewhat dated results
are tabulated in Table 6-13. The measured cadmium, emission
factors range from.0.021 kg/l015J (0.048 lb/1012Btu) to '
91 kg/!015J (212 lb/1012Btu). The average distillate value is
5.4 kg/l015J (13 lb/1012Btu), similar to the calculated value of
4.7 kg/iolsJ (11 lb/1012Btu). The values for No. 6 residual oil
from the 1979 study are higher than values reported in the other
studies despite the presence of PM control devices. The causes
of the large variation in measured cadmium emission factors are
unknown.39 Consequently, the test data in Table 6-13 should be
6-31
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TABLE 6-12. CALCULATED UNCONTROLLED CADMIUM EMISSION FACTORS
FOR FUEL OIL COMBUSTION
Fud oil type
Crude
No. 6 Residual
No. 2 Distillate
kg/1015 J
0.71
7.1
4.7
Calculated cadmium emission factors
lb/1012 Btu
1.7
17
11
g/Mg
fuel oil
0.03
0.3
0.21
10"3 Ib/ton
fuel oil
.0.06 -•
0.6
0.42
g/103 L
fuel oil
0.029
0.30
0.19
lb/10^ gal
0.25
2.5
1.5
used cautiously. More information on the sampling and analysis
of cadmium in fuel oil is presented in Section 9.
As a part of this study, three test reports prepared as a
part of the California "Hot Spots" program; were reviewed.49'51
The emission factors generated from these three reports are
summarized in Table 6-14. Each of the reports contained the data
on fuel oil characteristics needed to calculate cadmium input -
rates, so Table 6-14 contains both calculated emission factors
based on cadmium input levels and measured emission factors based
on stack tests. Because cadmium levels in all of the fuel oils
tested were below detection limits, all calculated emission
factors are reported as "less than" values. Note that all three
stack tests showed cadmium emission levels above the detection
limit in the stack but substantially below the detection limit
for cadmium in fuel oil. if cadmium levels in fuel oil'are close
to the detection limit, then the tests showed measured emissions
to be substantially less than cadmium input to the process. On
balance, these data provide little information for emission
factor development.
Given the limited emission test data available and the
concerns about possible biases in those data, the 'mass balance • •
6-32
-------
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6-34
-------
approach was used to estimate the best "typical" emission factor.
for distillate and residual fuel oil combustion.
The available information on uncontrolled cadmium emissions
from crude oil combustion is ambiguous. The limited test data
presented in Tables 6-13 and 6-14 show measured emission factors
that range "from 0.02 to 14 kg/1015 J (0.05 to 33 lb/1'012 Btu) , .a
range of almost three orders of magnitude. Because these data
are quite sparse and the relative quality of the data is
uncertain, the midpoint of the range was selected as the best
"typical" emission factor.
The uncontrolled emission factors for distillate, residual,
and crude oil are presented in Table 6-15. Data are insufficient
to develop controlled emission factors for fuel oil combustion.- -,
There is considerable uncertainty in these emission factor
estimates due to the variability of cadmium concentrations in
fuel oil and the uncertainty in sampling and analysis for
detecting cadmium. Therefore, these estimates should not be used
to determine emissions from specific oil-fired units.
TABLE 6-15. BEST TYPICAL CADMIUM EMISSION FACTORS FOR FUEL OIL COMBUSTION
Fuel oil type
Crude
No. 6 Residual
No. 2 Distillate
t===5==
kg/1015 J
7.0
7.1
4.7
==ss=ss=s=
Typical cadmium emission factors
lb/1012Btu
16
17
11
g/Mg
fuel oil
0.30
0.30
0.21
1 0^3 Ib/ton
fuel oil
0.60
0.60
0.42
=====
g/1 03 L
fuel oil
OJZ9
0.30
0.19
lb/1 06 gal
2.4
2.5
1.5
6.3. NATURAL GAS COMBUSTION
Natural gas is one" of the major fuels used throughout the
6-1, natural gas is used as an energy
6-35
-------
source in all four sectors, but the greatest uses are in the
industrial (46 percent) and residential (15 percent) sectors.'.
The five States that consume the largest-quantities of natural
gas are Texas, 'California, Louisiana, Illinois, and New.York. .'
However, only Louisiana and Oklahoma consume more energy via
natural gas combustion than by either coal or petroleum products
combustion.38 ,
6.3.1 Natural Gaa Characteristics45'8
Natural gas is considered to be a clean fuel. It consists
of primarily methane (generally 80 percent or greater by mass),
along with varying amounts of ethane, propane, butane, and inert
material (typically nitrogen, carbon dioxd.de, and helium) . The
average heating value of natural gas is about 8,900 kilocalories ••
per standard cubic meter (kcal/scm) (1,000 Btu per standard cubic
foot [Btu/scf]), with levels ranging from 8,000 to 9,000 kcal/scm
(900 to 1,100 Btu/scf). No data are available on the cadmium
content of natural gas. However, concentrations are expected to
be quite low. Little cadmium is expected to be found in raw gas,
and the processing steps used to recover liquid constituents and
to remove hydrogen sulfide from the raw gas should remove cadmium
that is contained in the raw gas.
i
! !
6•3•2 Process Description8
Natural gas combustion sources can be divided into four
categories: utility/large industrial boilers, small industry
boilers, commercial boilers, and residential furnaces. These
systems are configured differently, but the combustion processes
are comparable for all categories. -The natural gas and
combustion air are mixed in a burner and introduced to a
combustion chamber via a flame. The natural gas flame
temperature,_ which exceeds 1000°C (1800°F), will volatilize any
6-36 "
-------
cadmium in the fuel. Most of the cadmium will then condense onto
small particles and be exhausted as fine PM from the boiler or
furnace with the combustion gas stream. This exhaust stream is
the only source of cadmium emissions from natural gas combustion.
6-3.3 Emission Control
No control measures applied to natural gas -fired boilers and
furnaces are expected to affect cadmium emissions.
6.3.4 Emissions
No data are available on cadmium emissions from natural gas
combustion, but emissions are expected to be quite low. As
stated earlier, little cadmium is expected to be found in raw
gas, and, given the processing steps that natural gas undergoes,
any cadmium that is present would be removed from the raw gas.
Consequently, no cadmium emission factor is presented for natural
gas combustion.
6.4 WOOD COMBUSTION
Wood and wood wastes are used as fuel in both the industrial
and residential sectors. In the industrial sector, wood waste is
fired to industrial boilers to provide process heat, while wood
is fired to fireplaces and wood stoves in the residential
sectors. No data are available on the cadmium content of wood
and wood wastes. Consequently, the information below includes
process descriptions for the three combustion processes (boilers,
fireplaces, and wood stoves), descriptions of the control
measures used for wood- fired processes, and emission factors.
6-37
-------
6-4.1 Procegg
Wood waste combustion in boilers is mostly confined to those
industries for 'which it is available as a byproduct. These
boilers generate energy and alleviate possible solid waste
disposal problems. In boilers, wood waste "is normally burned in
the form of hogged wood, sawdust, shavings, .chips, 'sanderdust, or-
wood trim. Heating values for this waste range from about 2,200
to 2,700 kcal/kg (4,000 to 5,000 Btu/lb) of fuel on a wet, as-
fired basis. The moisture content is typically near 50 - weight •
percent but may vary from 5 to 75 weight percent, depending on
the waste type and storage operations. Generally, bark is the
major type of waste burned in pulp mills; either a mixture of
wood and bark waste or wood waste alone is, burned most frequently
in the lumber, furniture, and plywood industries.
As of 1980, approximately 1,600 wood- fired boilers were
operating in the United States, with a total capacity of over
30 gi.gawatts (GW) (i.o x 1011 Btu/hr) . No specific data on the
distribution of these boilers were identified, but most are
likely to be located in the Southeast, the Pacific Northwest
States, Wisconsin, Michigan, and Maine.
The most common firing method employed for larger wood- fired
boilers is the spreader stoker. Wood enters the furnace through
a fuel chute and is spread either pneumatically or mechanically
across the furnace, where small pieces of the fuel burn while in
suspension. Simultaneously, larger pieces of fuel are spread in
a thin, even bed on a stationary or moving grate. Natural gas or
oil is often fired in spreader stoker boilers as auxiliary fuel
to maintain a constant steam supply when the wood -waste supply or
composition fluctuates. Auxiliary fuel can also provide more
steam than can be generated from the waste supply alone.
6-38
-------
Another boiler type sometimes used for wood combustion is
the suspension-firing boiler. This boiler differs from a
spreader stoker in that small-sized fuel (normally-less than
-2 mm) is blown'into the boiler and combusted by-suspension firing
in air rather than on fixed grates. Rapid changes in combustion
rate and, therefore, steam generation rate are possible because
the finely divided fuel particles burn very quickly.'
Wood stoves are commonly used in residences as space
heaters, both as the primary source of residential heat and to
supplement conventional heating systems. The three different
categories of wood stoves are:
The conventional wood stove;
The noncatalytic wood stove; and •
The catalytic wood stove.
The conventional stove category comprises all stoves without
catalytic combustors not included in the other noncatalytic
categories (i.e., noncatalytic and pellet). Conventional stoves
do not have any emissions reduction technology or design -features
and, in most cases, were manufactured before July l, 1986-
Stoves of many different airflow designs may be in this category,
such as updraft, downdraft, crossdraft, and S-flow.
Noncatalytic wood stoves are those units that do not employ
catalysts but do have emission-reducing technology or features.
Typical noncatalytic design includes baffles and secondary
combustion chambers.
\
Catalytic stoves are equipped with 'a ceramic or metal
honeycomb device (called a combustor or converter) that is coated"
with a noble metal ^such as platinum or palladium. -The catalyst
..ma.teri?:1!.., red,uces the ignition^ temperature of_the unburned
6-39
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volatile organic compounds (VOC's) and carbon monoxide (CO) in
the exhaust gases, thus augmenting their ignition and combustion
at normal stove operating temperatures -.
Fireplaces are used primarily for aesthetic: effects and
secondarily as a supplemental heating source in houses and other
dwellings. Wood is the most common fuel - forifireplaces, but coal
and densified wood "logs" may also be burned. The user
intermittently adds fuel to the fire by hand.
All of the systems described abqve operate at temperatures
that are above the boiling point of cadmium. Consequently, any
cadmium contained in the fuel will be emitted with the combustion
gases as enriched fine EM. The combustion exhaust stack is the
only source of cadmium emissions•from these processes.
' ' i
6-4.2 Emission Control Measure*?8
Although some wood stoves use control measures to reduce VOC
and CO emissions, these techniques are'not expected to affect '
cadmium emissions. However, wood waste boilers do employ PM
control equipment, which may provide some reduction. These
systems are described briefly below.
Currently, the four most common control devices used to
reduce PM emissions from wood-fired boilers are.mechanical
collectors, wet scrubbers, ESP's, and fabric filters..,Of.these
controls, only the last three have the potential for significant
cadmium reduction.
" \ „ ,
The most widely used wet scrubbers for wood-fired boilers
are venturi scrubbers. With gas-side pressure drops exceeding '
4- fcilopascals (is inches of water), PM collection-efficiencies of
90 percent or greater have been reported fpr,.yenturi,,SQpibbers. ...,.
6-40
-------
operating on wood-fired boilers. No data were located on the
performance of these systems relative to cadmium emissions, -but -
it is expected to be somewhat less because cadmium is likely to
be concentrated in the fine PM, which is less readily collected
by control devices.
Fabric filters (i.e.', baghouses) and ESP's are" employed when
PM collection efficiencies above 95 percent are required.
Collection efficiencies of 93 to. 99.8 percent for PM have been
observed for ESP's operating on wood-fired boilers, but cadmium
efficiencies-are likely to be somewhat less because of the reason
cited above. Fabric filters have had limited applications to
wood-fired boilers because of fire hazards. Despite
complications, fabric filters are generally preferred for boilers
firing salt-laden wood. This fuel produces fine PM with a high -
salt content for which fabric filters can achieve high collection
efficiencies. In two tests of fabric filters operating on
salt-laden wood-fired boilers, PM collection efficiencies were
above 98 percent. No data are available on cadmium emission
reduction for fabric filtera^.but because cadmium is enriched
onto fine PM, which is less readily collected than PM as a whole,
it is expected that efficiencies will be somewhat lower.
6.4.3 Emissions
The primary source of cadmium emissions from wood combustion
processes is the combustion gas exhaust stack. Small quantities
of cadmium also may be emitted with the fugitive PM emissions
from bottom and fly ash handling operations.
The data on cadmium emissions from wood combustion are quite
limited. A recent study to update the wood waste combustion
section of AP-42 provided a range and average typical emission
boilers based on. the-results-.---
6-41.
-------
of seven tests. Table 6-16 presents the range and average
obtained from those tests as well as the range and average from a
California "Hot Spots" test of-a fluidized-bed wood-fired boiler
not included in the AP-42 update.52'5^
i
TABLE 6-16. SUMMARY OF CADMIUM EMISSION FACTORS FOR WOOD COMBUSTION
Operation
Wood waste boiler3
Wood waste boiler-"Hot Spots"b
Residential wood stove-
conventional
Residential wood stove-
noncatalytic
Residential wood stove-catalytic
Cadmium emission factors
10~3 g/Mg wood burned
Range
1 .3-270
4.4-10
_
—
-
Mean.
8.5
7.4
11
36
10
23
10~6 Ib/ton wood burned
2.7-540
8.8-20
—
. „
».
17
15
22
72
20
46
Source: References 52 - 54.
a
Based on an assumed heating value of 10,460 kJ/kg (4,500 Btu/lb) and PM control.
bBased on a heating value of 19,220 U/kg (8,270 Btu/lb) and PM control with multiclones and
A review of the literature produced four emission factors
for residential wood stove combustion, which are also presented
in Table 6,16.52'54 Three of the four emission factors were
provided by the section on residential wood combustion in the
recent AP-42 and included emission factors for conventional,
noncatalytic, and catalytic wood stove combustion. However, the
data used to develop these emission factors showed a high degree
of variability within the source population. The fourth emission
factor from the literature" was based on only a single test at one
location of an uncontrolled conventional wood stove. Because
cadmium content in wood may vary with local soil conditions, this
6-42
-------
value may not be representative of conditions across the United
States. Because of these uncertainties, the emission factors
should be used cautiously.
6.5 MUNICIPAL WASTE COMBUSTION
Refuse or municipal solid waste (MSW) consists primarily of
household garbage and other nonhazardous commercial,
institutional, and industrial solid waste. Municipal waste
combustors (MWC's) are used to reduce the .mass and volume of MSW
that ultimately must be landfilled.
Currently, over 160 MWC plants are in operation in the
United States with capacities greater than 36 megagrams per day
(Mg/d) (40 tons per day [ton/d] ) and a total capacity of
approximately 100,000 Mg/d (110,000 ton/d) of MSW. It is
predicted that by 1997, the total MWC capacity will approach
150,000 Mg/d (165,000 ton/d), which represents over 28 percent of
the estimated total amount of MSW generated in the United States
by the year 2000. However, because permitting difficulties have
delayed construction of new units, these projections may be
optimistic. Table 6-17 shows the geographic distribution of MWC
units and capacities by States.55
In addition to these large units, a number of -smaller,
specialized facilities around the United States also bum MSW.
However, the- total nationwide capacity of those smaller units is
only a small fraction of the total capacity of the units with
individual capacities of 36 Mg/d (40 ton/d) and larger.
6°5-1 Municipal Solid Waste
Municipal solid waste is a heterogeneous mixture of the
various materials f ound-in-household,- commercial , and industrial
6-43
-------
TABLE 6-17. SUMMARY OF GEOGRAPHICAL DISTRIBUTION OF MWC FACILITIES
1 State
AK
A 1
AL
AR
f* A
CA
F\f*
DC
f^r*
DE
f"t
FL
f* A
GA
tJI
HI
1 A
IA
IPS
ID
• I
IL
it 1
IN
i MA
1 * • f^
MD
1 ft Jlf~
ME
1 ft Jl
I Ml
I ft Jlfcl
MN
ft j^%
MO
ft Jlf*
MS
ft J*T*
! MT
i k|^%
NC
ft II 1
NH
K> 1
NJ
fcfV/
NY
Ol 1
OH
/"MX
OK
/•^o
OR
O A
PA
nn
PR
-------
wastes. Major constituents in typical municipal waste are listed
in Table 6-18. No data on the concentration of cadmium in MSW
streams were located, but known sources of cadmium in MSW are
batteries," discarded electrical equipment and wiring, and
plastics.
TABLE 6-18. CURRENT AND FORECAST COMPOSITION OF DISPOSED RESIDENTIAL
AND COMMERCIAL WASTE (WEIGHT PERCENT)
Component
Paper and Paperboard
Yard Wastes
Food Wastes
Glass
Metals
Plastics
Wood
Textiles
Rubber and Leather
Miscellaneous
Totals
===^=^=r======^
Year
1980
33.6
18.2
9.2
11.3
10.3
6.0
3.9
2.3
3.3
_L9_
100.0
'
1990
38.3
17.0
7.7
8.8
9.4
8.3
3.7
2.2
2.5
2.-I
100.0
'
Source: Reference 56.
6-5.2 Process Descripfc-Lnn^S, 55, 57, 58
The three principal MWC classes are mass burn, refuse-
derived fuel (RDF), and modular combustors. The paragraphs below
briefly describe some of the key design and operating
characteristics of these different combustor types.
Refstances.. 45, 55, and 57 provide more detailed process
6-45
-------
descriptions and process diagrams for each of the systems
described below.
In mass burn units, the MSW is combusted without any
preprocessing other than removal of items too large to go through
the feed system. In a typical .mass burn combustor, refuse is fed
onto a moving grate. Combustion %ir in excess of. stoichiometric
amounts is supplied below (underfire air) anci above (overfire
air) the grate. Mass burn combustors are usually erected at the
site (as opposed to being prefabricated at another location) and
range in size from 46 to 900 Mg/d (50 to 1,000 tons/d) of MSW
throughput per unit. The mass burn combustor category can be
divided into mass burn refractory wall (MB/REF), mass
burn/waterwall (MB/WW), and mass burn/rotary waterwall (MB/RC)
designs. The two most common, MB/REF and MB/WW, are described
below.
i ' i
The MB/REF combustors are older facilities that comprise
several designs. This type of combustor is continuously fed and
operates in an excess air mode with both underfire and overfire
air provided. The waste is moved on a traveling grate and is not
mixed as it advances through the combustor. As a result, waste
burnout or complete combustion is inhibited by fuel bed
thickness, and there is considerable potential for unbumed waste
to be discharged into the bottom ash pit. Rocking and
reciprocating grate systems mix and aerate the waste bed as it
advances through the combustion chamber, thereby improving
contact between the waste and combustion air and increasing the
burnout of combustibles. The system generally discharges the ash
at the end of the grates to a water quench pit for collection and
disposal in a landfill. The MB/REF•combustors have a
refractory-lined combustion chamber and operate at relatively
high excess air rates to prevent excessive temperatures/ which "
6-46
-------
can result in refractory damage, slagging, fouling, and corrosion
problems.
Because of their operating characteristics, the tracking
grate systems may have cool ash pockets in which cadmium is not
exposed, to high temperatures. and is thereby retained in the ash,
rather than being exhausted with the.combustion gas stream. ' '
Consequently, cadmium may be emitted as fugitive emissions from
ash handling. However, the combustion stack is the primary
source of cadmium emissions. In the rocking and reciprocating
grate systems, essentially all cadmium will be exhausted with the
combustion gas.
The MB/WW design represents the predominant technology in
the existing population of large MWC's, and it is expected that •
over 50 percent of new units will be MB/WW designs. In MB/WW
units, the combustor walls are constructed of metal tubes that
contain pressurized water and recover radiant energy from the
combustion chamber. With this type of system, unprocessed waste
(after removal of large, bulky items and noncombustibles) is
delivered by an overhead crane to a feed hopper that conveys the
waste into the combustion chamber. Nearly all modern MB/WW
facilities utilize reciprocating grates or roller grates to move
the waste through the combustion chamber. The grates typically
include two or three separate sections where designated stages in
the combustion process occur. On the initial grate section,
referred to as the drying grate, the -moisture content of the
waste is reduced prior to ignition. In the second grate section,
the burning grate, the majority of active burning takes place.
The third grate section, referred to as the burnout or finishing
grate, is where remaining combustibles in the waste are burned.
Bottom ash is discharged from the finishing grate into a water-
filled ash quench pit or ram discharger. From there, the. moist
ash._is Aischa-rged to, a., conveyor system and transported .to an ^ash ._
6-47
-------
loading area or storage area prior to disposal. Because the
waste bed is exposed to fairly uniform high combustion
temperatures, cadmium will volatilize and condense on small
particles. Most cadmium will be-exhausted as fine PM with the
combustion gases, although some may be partitioned with the ash.
Refuse-derived fuel combustors burn"MSWthat has been
processed to varying degrees, from simple removal of bulky and
noncombustible items accompanied by shredding, to extensive
processing to produce a finely divided fuel suitable for co-
firing in pulverized coal-fire boilers. Processing MSW to RDF
generally raises the heating value of the waste because many of
the noncombustible items have been removed.
A set of standards for classifying RDF types has been
established by the American Society for Testing and Materials
The type of RDF used is dependent on the boiler design. Boilers
that are designed to burn RDF as the primary fuel usually utilize
spreader stokers and fire fluff RDF in a semi-suspension mode.
This mode of feeding is accomplished by using an air swept
distributor, which allows a portion of the feed to burn in
suspension and the remainder to be burned out after falling on a
horizontal traveling grate. 'The number of RDF distributors in a
single unit varies directly with unit capacity. The distributors
are normally adjustable so that the trajectory of the waste feed
can be varied. Because the traveling grate moves from the rear
to the front of the furnace, distributor settings are adjusted so
that most of the waste lands on the rear two-thirds of the grate
to allow more time for combustion to be completed on the grate.
Bottom ash drops into a water-filled quench chamber. Underfire
air is normally preheated and introduced beneath the grate by a
single plenum. Overfire air is injected.through rows of high
pressure nozzles, providing a zone for mixing and completion of
the combustion process. Because essentially all of the waste is
6-48
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exposed to high combustion temperatures on the grate, most of the
cadmium in .the RDF will be discharged with the combustion gas
exhaust as fine PM.
In a fluidized-bed combustor (FBC) ,. .fluff or pelletized RDF
is combusted on a turbulent bed of noncombustible material, such
as.limestone, sand, or silica. In its simplest form, the FBC
consists of a combustor vessel equipped with a gas distribution
plate and underfire air windbox at the bottom. The combustion
bed overlies the gas distribution plate. The RDF may be injected
into or above the bed through ports in the combustor wall. The
combustor bed is suspended or "fluidized" through the
introduction of underfire air at a high flow rate. Overfire air
is used to complete the combustion process.
Good mixing is inherent in the FBC design. Fluidized-bed
combustors have uniform gas temperatures and mass compositions in
both the bed and in the upper region of the combustor. This
uniformity allows the FBC's to operate at lower excess air and
temperature levels than conventional combustion systems. Waste-
fired FBC's typically operate at excess air levels between 30 and
100 percent and at bed temperatures around 815°C (1500°P). At
this temperature, most of the cadmium will be volatilized. The
cadmium then condenses onto small particles and is exhausted with
the combustion gas stream as fine PM.
In terms of number of facilities, modular starved- -
(or controlled-) air (MOD/SA) combustors represent a large
segment of the existing MWC population. .However, because of
their small sizes, they account for only a small percentage of
the total capacity. The basic design of a MOD/SA combustor
consists of two separate combustion chambers, referred to as the
"primary" and "secondary" chambers. Waste is batch-fed
.intermittently.._to_the pr.imary_chamber-by a.hydraulically -.-
6-49
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activated ram. The charging bin is filled by a front-end loader
or by other mechanical systems. Waste i, fed automatically on a
set frequency, with generally 6 to 10 minutes between charges.
Waste is moved through the-primary combustion chamber by
exther hydraulic transfer rams or reciprocating grates
Combustors using transfer rams have 'individual hearths upon which
combustion takes place. Grate systems generally include two
separate grate sections, in either case, waste retention times
in the primary chamber are lengthy, lasting up to 12 hours
Bottom ash is usually discharged to a wet quench pit.
_ The quantity of air introduced in the primary chamber
defines the rate at which waste burns. Combustion air is
introduced in the primary chamber at substoichiometric levels •
resulting in a flue gas rich in unbumed hydrocarbons. The
combustion air flow rate to the primary chamber is controlled to
maintain an exhaust gas temperature set point [generally 650° to
980'C (12000 to 1800'F)], which corresponds to about 40 to
, 60 percent theoretical air. As the hot, fuel-rich flue gases
flow to the secondary chamber, they are mixed with excess air to
complete the burning process. Because the temperature of the
exhaust gases from the primary chamber is above the autoignition
poznt, completing combustion is simply a matter of introducing
axr to the fuel-rich gases. The amount of air added to the
secondary chamber is controlled to maintain a desired flue gas
exit temperature, typically .980' to-l200«C (1800<> to 2200°F) At
these primary chamber and secondary chamber temperatures,
essentially all of the cadmium contained in the waste is expected
to be volatilized, condense onto small particles, and be emitted
as fine EM from the secondary chamber with 'the combustion gas
stream.
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6.5.3 Emission
Cadmium emissions from-MWC units are generally:- controlled by
condensing the cadmium vapors from the .combustion. chamber to-
particle form and then removing the particle-phase cadmium with a
high- efficiency PM control device. The PM~ control devices most"
frequently used in the United States are ESP's and fabric
filters. Typically, newer MWC systems use a combination of gas
cooling and duct sorbent injection (DSI) or spray dryer (SD)
systems upstream of the PM device to reduce temperatures and
provide a mechanism for acid gas control. The paragraphs below
briefly describe the DSI and SD processes. Because the ESP's and
FF's used on MWC's are comparable to those used on other •
combustion systems, they are not described. Reference 54
provides more detailed descriptions of the control systems- and -.
additional information on' the performance of these .systems:
. Spray drying in combination with either fabric filtration or
an ESP is the most frequently used acid gas control technology
for MWC's in the United States. Spray dryer/ fabric filter
systems are more common than SD/ESP systems and are used most on
new, large MWC's. In the spray drying process, lime is slurried
and then injected into the SD through either a rotary atomizer or
dual -fluid nozzles. The key design and operating parameters that
significantly affect SD performance are the SD's outlet approach
to saturation temperature and lime- to-acid gas stoichiometric
ratio. The SD outlet temperature is controlled, by, the amount of
water in the lime slurry.
With DSI, powdered sorbent is pneumatically injected into
either a separate reaction vessel or a section of flue gas duct.
located downstream of the combustor economizer. Alkali in the
sorbent (generally calcium) reacts with HC1 and S02~to form
salts <&^j.^Lc^^^Ad^JC*Cl2]^d_ calcium sulfite
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[CaSO3]). Some units also use humidification or other
temperature control measures upstream from the collection device.
Reaction products, fly ;ash,. and unreacted sorbent are .collected
with either an"ESP or fabric filter.
Based on a summary.of MWC cadmium emission data in
Reference 55, substantial cadmium removal can be achieved using
spray drying or duct sorbent injection in combination with fabric
filtration or an ESP. A cadmium removal efficiency of 98 percent
can be achieved with an SD/ESP system, slightly lower than the
cadmium control'with an SD/FF system (99 percent) because of the
metals enrichment of the fine particles. If the removal '
efficiency of PM with an ESP is 98 percent: or greater, the
.removal efficiency of cadmium with an ESP will generally be at
least 95 percent. Removal efficiencies greater than 95 percent -
can generally be achieved by DSI/ESP systems. A DSI/FF system
can achieve 99. percent removal of cadmium.
6.5.4 Emissions^5
The primary source of cadmium emissions from municipal
combustors is the combustion gas exhaust stack. However, small
amounts of cadmium may be emitted as part of the fugitive PM
emissions from fly ash handling, particularly if highly efficient
dry control systems are used.
A recent study conducted to update the municipal.waste
combustion section of AP-42 provided a comprehensive review of
the available MWC cadmium emission data/which are summarized in
Table B-2 of Appendix B. The emission data that are presented in
Appendix B are in- concentration units rather than emission
factors because the study found that most of the test reports
contained insufficient process data to generate emission factors.
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After reviewing the test data, the authors concluded that
the development of emission factors for MWC's, using only the
test reports which estimated feed rates, would.eliminate data
from so many facilities, especially key facilities, that the
values derived were not likely to be representative of the entire
MWC population. In addition, the subjective nature of the refuse
feed rates called into question the validity of the limited data.
Consequently, emission factors were developed using the F-factor,
which is the ratio of the gas volume of the products of
combustion to the heating value of the fuel. This approach,
presented in EPA Method 19, requires an F-factor and an estimate
of the fuel heating value. For MWC's, the F-factor is
0.257 dscm/MJ (9,570 dscf/106 Btu) (at 0 percent 02). For all
combustor types, except RDF combustors, a heating value of
10,500 kJ/kg (4,500 Btu/lb) refuse was assumed. For RDF
combustor. units, the processed refuse has a higher heating value,
and a heating value of 12,800 kJ/kg (5,500 Btu/lb) was assumed.
Overall, these data are representative of average values for
MWC's.
The resultant best typical emission factors for different
combinations of combustor and control device are presented in
Table 6-19. While this procedure does provide good average
emission factors that represent an industry cross section, it
should not be used to convert individual data points in
Appendix B. The assumed F-factor and waste heating values above
may not be appropriate for specific facilities.
6.6 SEWAGE SLUDGE INCINERATORS
Currently, about 2.00 sewage sludge incinerators (SSI's)
operate in the United States using one of three technologies:
multiple hearth, fluidized-bed, and electric infrared. Multiple
hearth units predominate, with over 80 percent-of the identified,
•i-_
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TABLE 6-19. BEST TYPICAL CADMIUM EMISSION FACTORS FOR MUNICIPAL
WASTE COMBUSTORS
Typical cadmium emission factors
Combustor
type
10"3 Ib/ton waste
g/Mg waste
Mass Burn/Waterwall
Mass Burn/Rotary
Waterwall
Mass Burn/Refractory Wall
Refuse-Derived Fuel-Fired
Modular/Excess Air
Modular/Starved Air
Source: Reference 55.
aUN « uncontrolled, SD - spray dryer, FF =* fabric filter, ESP = electrostatic precipitator,
DSI ** duct sorbent injection.
6-54
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operating SSI's being of that type. About 15 percent of the
SSI's are fluidized-bed combustors; 3 percent are electric
infrared; and the remainder cofire sewage sludge with municipal
solid waste.59
Figure 6-1 shows the distribution of sewage sludge
incinerators in the United States60 Most facilities are located
in the Eastern United States, but a substantial number are also
located on the West Coast. New York has the largest number of
SSI facilities with 33, followed by Pennsylvania and Michigan
with 21 and 19, respectively. About 1.5 x 10s Mg
(1.6 x 10 tons) of sewage sludge on a dry basis are estimated to
be incinerated annually.59
No data have been located on the cadmium content of sewage '
sludge.
The sections below provide SSI process descriptions, a
discussion of control measures, and a summary of cadmium emission
factors.
6.6.1 Process Description45'59
Figure 6-2 presents a simplified diagram of the sewage
sludge incineration process, which involves two primary steps.
The first step in the process of sewage sludge incineration is
the dewatering of the sludge. Sludge is generally dewatered
until it is about 15 to 30 percent solids. When it is more than
25 percent solids, the sludge will usually burn without auxiliary
fuel. After dewatering, the sludge is sent to the incinerator,
and thermal oxidation occurs. The unburned residual ash is
removed from the incinerator, usually on a continuous basis, and
is disposed. A portion of the noncombustible waste, as well as
-unburned volatile organic compounds, is carried out of the - -
6-55
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HI-3
Figure 6-1. Distribution of sewage sludge incinerators in the U.S.60
6-56
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'GAS EXHAUST
ASH
• FUGITIVE EMISSDN8
I POTENTIAL SOURCES OFMEBCURY EMISSIONS
PRECOOLER AND -
VENTURI WATER S J
6'?L-. ^c??.? flow diagram for sludge.incineration.
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coinbustor through entrainment in the exhaust gas stream. Air
pollution control devices,. primarily wet scrubbers, are used to
remove the entrained pollutants from the exhaust gas stream. The
gas stream is then exhausted, and,the collected pollutants are
sent back to the head of the wastewater treatment plant in the
scrubber effluent. As shown in Figure'6-2," the primary source of
cadmium emissions •from the SSI process is the combustion stack.
Some fugitive emissions may be generated from ash handling, but
the quantities .are expected to be small. Because cadmium is
relatively volatile, most cadmium will leave the combustion
chamber as fine PM in the exhaust gas, although some cadmium may
be found in the ash residue.
The paragraphs below briefly describe the three primary SSI
processes used in the United States. References 45 and 59
provide more detailed descriptions and process diagrams.
The basic multiple hearth furnace is cylindrical in shape
and is oriented vertically. The outer shell is constructed of
steel, lined with refractory, and surrounds a series of
horizontal refractory hearths.. A hollow cast iron rotating shaft
runs through the center of the. hearths. Attached to the central
shaft are the rabble arms with teeth shaped to rake the sludge in
a spiral motion, alternating in direction from the outside in,
then inside out, between hearths. Typically, the upper and lower
hearths are fitted with four rabble arms, and the middle hearths
are fitted with two. Cooling air for the center shaft and rabble
arms is introduced into the shaft by a fan located at its base.
Burners that provide auxiliary heat are located in the sidewalls
of the hearths.
r
Partially dewatered sludge is typically"fed onto the
perimeter of the top hearth. Typically,'the rabble arms move the
sludge through the incinerator as th$ motion of-, the .rabble arms.
6-58
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rakes the sludge toward the center shaft, where it drops through
holes located at the center of the hearth. This process is
repeated in all of the subsequent hearths, with the sludge moving
in opposite directions in adjacent hearths. The effect of the
rabble motion is to break up solid material to allow better
surface .contact with heat and oxygen.
Ambient air is first ducted through the central shaft and
its associated rabble arms. This air is then taken from the top
of the shaft and recirculated onto the lowermost hearth as
preheated combustion air. The combustion air flows upward
through the drop holes in the hearths, countercurrent to the flow
of the sludge, before being exhausted from the top hearth.
Multiple hearth furnaces can be divided into three zones.
The upper hearths comprise the drying zone where most of the
moisture in the sludge is evaporated. The temperature in the
drying zone is typically between 425° and 760°C (800° and
1400°F). Sludge combustion occurs in the middle hearths (second
zone) as the temperature is increased between 815° and 925°C
(1500° and 17QO°F). when exposed to the temperatures in both
upper zones, most cadmium will be volatilized, condense on small
particles, and then be discharged as fine PM in the exhaust gas.
Some of the cadmium may be partitioned with the ash. The third
zone,, made up. of the lowermost hearth(s) , is the cooling zone.
In this zone, the ash is cooled as its heat is transferred to the
incoming combustion air.
Fluidized-bed combustors (FBC's) are cylindrically shaped
and oriented vertically. The outer shell is constructed of steel '
and is lined with refractory. Tuyeres (nozzles designed to
deliver blasts of air) are located at the base of the furnace
within a refractory-lined grid. A bed of sand rests upon the
6-59
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furnace. Air .injected through the tuyeres, at pressures from 20
to 35 kPa (3 to 5 psig), simultaneously fluidizes the bed of hot
sand and the incoming .sludge. Temperatures of 725° to 825°C
(1350° to. 1500»F.) , which are sufficient to vaporize most cadmium
contained in the sludge, are maintained in the bed. As the
sludge burns, fine ash particles, including cadmium, are carried
out the top of the furnace with the'exhaust gas. '
An electric incinerator consists of a horizontally oriented,
insulated furnace. A woven wire belt conveyor extends the length
of the furnace, and infrared heating elements are located in the
roof above the conveyor belt. Combustion air is preheated by the
flue gases and is injected into the discharge end of the furnace.
Electric incinerators consist of a number of prefabricated
modules that are linked together to provide the necessary furnace
length. The dewatered sludge cake is conveyed into one end of
the incinerator. An internal roller mechanism levels the sludge
into a continuous layer approximately 2.5 centimeters (cm)
(1 inch tin.]) thick across the width of the belt. The sludge is
sequentially.dried and then burned as it moves beneath the
infrared heating elements. Ash is discharged into a hopper at
the opposite end of the furnace. The preheated combustion air
enters the furnace above the ash hopper .and is further heated by
the outgoing ash. The direction of air flow is countercurrent to
the movement of the sludge along the conveyor.
i " , , i " '.
6.6.2 Emission Control Measures59/61
Most SSI's are equipped with some type of wet scrubbing
system for PM control. Because these systems provide gas cooling
as well as PM removal,' they can provide some cadmium control.
The paragraphs below briefly describe the wet scrubbing systems
typically used on existing SSI's. ' ...-..-.
6-60
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Wet scrubber controls on SSI's range from low pressure drop
spray towers and wet cyclones to higher pressure drop venturi
scrubbers and venturi /impingement tray scrubber combinations.
The most widely used control device applied to a multiple ^hearth
incinerator is the impingement tray scrubber. Qlder units use
the tray scrubber alone while combination venturi/impingement
tray scrubbers are widely applied' to newer multiple hearth
incinerators and to fluidized-bed incinerators. Most electric
incinerators and some fluidized-bed incinerators use venturi
scrubbers only.
In a typical combination venturi/impingement tray scrubber,
hot gas exits the incinerator and enters the precooling or quench
section of the scrubber. Spray nozzles in the quench section
cool the incoming gas, and the quenched gas then enters the
venturi section of the control device. Venturi water is usually
pumped into an inlet weir above the quencher. The venturi water
enters the scrubber above the throat and floods the throat
completely. Most venturi sections come equipped with variable
throats to allow the.pressure drop to be increased, thereby
increasing PM efficiency. At the base of the flooded elbow, the
gas stream passes through a connecting duct to the base of the
impingement tray tower. Gas velocity is further reduced upon
entry to the tower as the gas stream passes upward through the
perforated impingement trays. Water usually enters the trays
from inlet ports on opposite sides and flows across the tray. As
gas passes through each .perforation in the tray, it creates a jet
that bubbles up the water and further entrains solid particles.
At the top of the tower is a mist eliminator to reduce the
carryover of water droplets in the stack effluent gas.
.,According to the literature' the control of cadmium
emissions with wet scrubber controls is expected to be less than
,the_c_ontrc,l_^Qf_..totar PM emissions. : In a study of emissions from
6-61
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four municipal wastewater sludge incinerators, three multiple
hearth and one fluidized-bed, cadmium and other heavy metals were
found to be enriched in the fine particles,. .which are not as
efficiently removed by ^scrubbers as' larger particles..61 The
efficiency "data for cadmium emissions control for sewage sludge
incineration are very limited and, therefore, are not completely
reliable. Based on two tests reported"in Reference 59, an
average cadmium control efficiency of 75 percent can be achieved
with a combination of venturi scrubber and impingement scrubber
systems. By contrast, based on the results of three other tests,
an average of 95 percent control of PM can be achieved with an
impingement scrubber alone. About 86 percent PM control was
achieved with a venturi scrubber in another test.
6.6.3 Emissions
The primary source of cadmium emissions from sewage sludge
incineration is the combustion gas exhaust stack. However, small
quantities of cadmium also may be emitted with the fugitive PM
emissions generated from bottom and fly ash handling operations.
As a part of .the recent update of AP-42, data have been
developed on cadmium emissions from SSI's.59 These data are
tabulated in Appendix B, Table B-3 and summarized in Table 6-20.
Because no data are available on cadmium concentrations in
sludge, the test data in Table 6-20 represent the best typical
emission factors for sewage sludge incineration.
6.7 MEDICAL. WASTE INCINERATION
Medical waste includes infectious and noninfectious wastes
generated by a variety of facilities engaged in medical care,
veterinary care, or research activities such as hospitals,
clinics, doctors' and dentists' offices, nursingJhomes,
6-62
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TABLE 6-20. SUMMARY OF CADMIUM EMISSION FACTORS
FOR SEWAGE SLUDGE INCINERATORS
Incinerator
type3
MH
MH
MH
MH
MH
MH
MH
MH
FB
=====
Control
status13
UN
VS
IS
VS/IS or
VS/IS/AB
CY
CY/VS or
CY/VS/IS
ESP
FF
IS or VS/IS
===========
-BDeaaasE&cs
No. data
points
4
2
2
5
3
2
1
1
5
=====
=================
Cadmium emission factors
g/Mg dry sludge
Range
* 0.0010-49
0.17-0.65
1.2-1.5
0.32-7.8
0.86-32
8,1-25
—
—
0.0030-1 .4
================
Mean
26
0.41
1.4
3.0
12
17
0.17
0;014
0.48
============
10'3 Ib/ton dry sludge
0.0020-98
0.34-1 .3
2.4-3.0
0.64-16
1 .7-65
16-50
.».
•••
0.0060-2.9
53'
0.82
2 7
5.9
25
33
0.35
0.028
0.97
Source: Reference 59.
aMH = multiple hearth, FB = fluidized-bed.
bUN = uncontrolled, VS = venturi scrubber, IS = impingement scrubber, AB = afterburner
CY = cyclone, ESP = electrostatic precipitator, FF = fabric filter.
veterinary clinics and hospitals, medical laboratories, and
medical and veterinary schools and research units. Medical waste
is defined by the U. S. EPA as "any solid waste which is
generated in the diagnosis, treatment, or immunization of human
beings or animals, in'research pertaining thereto, or in the
production or testing of biologicals.» A medical waste
incinerator (MWI) is any device that burns such medical waste.62
Recent estimates developed by EPA suggest that about
3«06,ini:Lli011 Mg _(3_._36_million tons) of medical waste are produced
6-63
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annually in the United.States. Approximately 5,000 MWI's, which
are distributed.geographically throughoutthe United States, are.
used to treat this waste. • Of these 5,000 units, about 3,000 are
located at hospitals ;< about 150 are larger commercial facilities;
and the remainder are•distributed among veterinary facilities,
nursing homes, laboratories, and other miscellaneous
.facilities.'63 « ' . . , • , ..
Available information indicates that these MWI systems can
be significant sources of cadmium emissions. Cadmium emissions .
result from cadmium-bearing materials contained in the waste.
Although concentrations of specific metals in the waste have not
been fully characterized, known cadmium sources in medical waste
include batteries, pigments, and plastics. Batteries, primarily
nickel-cadmium and mercury-cadmium batteries, are a major cadmium
source. Mercury-cadmium batteries are used in transistorized
equipment, hearing aids, watches, calculators, computers, smoke
detectors, tape recorders, regulated power supplies, radiation
detection meters, scientific equipment, pagers, oxygen and metal
monitors, and portable electrocardiogram monitors. The nickel-
cadmium battery is the most widely used rechargeable household
battery and is used in computers, hearing aids, and pocket
calculators. Cadmium pigments are primarily used in plastics but
are also used in paints, enamels, printing inks, rubber, paper,
and painted textiles.64 Plastics are used in disposable
instruments, syringes, petri dishes, plastic containers,
packaging, bedpans, urine bags, respiratory devices, dialysis
equipment, etc.65 All of these materials can be routed to an
MWI, thereby contributing to cadmium emissions from this source
category.
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6.7.1 Process Description
Although the ultimate destination of almost all medical .
waste produced'in the United States is a solid waste landfill,
the waste generally must be treated before it can be landfilled.
The primary functions of MWI facilities are to render the waste
biologically innocuous and to reduce the volume and mass of
solids that must be landfilled by combusting the organic material
contained in the waste. Over the years, a wide variety of MWI
system designs'and operating practices have been used to
accomplish these functions. To account for these system
differences, a number of MWI classification schemes have been
used in past studies, including classification by waste type
(pathological, mixed medical waste, red bag waste, etc.),
classification by operating mode (continuous, intermittent,
batch), and classification by combustor design (retort,
fixed-hearth, pulsed-hearth, rotary kiln, etc.). Some insight
into MWI processes, emissions, and emissions control is provided
by each of these schemes. However, -because the available
evidence suggests that cadmium emissions are affected primarily
by waste characteristics, the characterization and control of
cadmium emissions from MWI's can be discussed without considering
other MWI design and operating practices in detail. The
paragraphs below provide a generic MWI process -description and
identify potential sources of cadmium emissions. More detailed
descriptions of specific MWI design and operating practices can
be found in References 66 through 68.
A schematic of a generic MWI system that identifies the
major components of the system is shown in Figure 6-3. As
indicated in the schematic, most MWI's are multiple-chamber
combustion systems that comprise primary,, secondary, and possibly
tertiary chambers. The primary components of the MWI process are
_vras*:e-char?in5 system, .the primary chamber, the, ash handling
6-65
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to .
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6-66
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system, the secondary chamber, and the air pollution control
system, which are discussed briefly below.
Medical waste is introduced to the primary chamber via the
waste-charging system. The waste can be charged either manually
or mechanically. With manual charging, which is used only on
batch and smaller (generally older) intermittent units, the
. operator opens a charge door on the side of the primary chamber
and tosses bags or boxes of waste into the unit. When mechanical
feed systems are employed, some type of mechanical device is used
to charge the waste to the incinerator. The most common
mechanical feed system is the hopper/ram assembly. In a
mechanical hopper/ram feed system, the following steps take
place: (1) waste is placed into a charging hopper manually, and
the hopper cover is closed; (2) a fire door isolating the hopper"
from the incinerator opens; (3) the ram moves forward to push the
waste into the incinerator; (4) the ram reverses to a location
behind the fire door; (5) after the fire door closes, a water
spray cools the ram, and the ram retracts to the starting
position; and (6) the system is ready to 'accept another charge.
The entire hopper/ram charging sequence normally functions as a
controlled, automatically-timed sequence to eliminate
overcharging. The sequence can be activated by the operator or
for larger, fully automated incinerators, it may be activated at
preset intervals by an automatic timer.67'68
The potential for cadmium emissions from the waste-charging
systems is low. Mechanical systems are generally operated with a
double-door system to minimize fugitive emissions. Small
quantities of fugitive emissions may be generated while the
chamber door is open during manual charging, but no data are
available on the magnitude of these emissions.
6-67
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The primary chamber (sometimes called the "ignition"
chamber) accepts the waste and begins the combustion process.
Most modem MWI's operate this chamber in a "controlled-air" mode
to maintain combustion air levels at or below stoichiometric
_requirements. The objectives of this controlled-air operation
are to provide a more uniform release of volatile organic
materials to the secondary chamber and to minimize entrainment'of
solids in these off-gases. Three processes occur in the primary
chamber. First, the moisture in the waste is volatilized.
Second, the volatile fraction of the waste is vaporized, and the
volatile gases are directed to the secondary chamber. Third, the
fixed carbon remaining in the waste is combusted.
The primary chamber generates two exhaust streams--the
combustion gases that pass to the secondary chamber and the solid
ash stream that is discharged. Any metal compounds in the waste,
including cadmium, are partitioned to these two streams in one of
three ways. The metals may be retained in the primary chamber
bottom ash and discharged as solid waste; they may be entrained
as PM in the combustion gases; or they may be volatilized and
discharged as a vapor with the combustion gases. Because the
primary chamber typically operates in the range of 650° to 820«C
(12000 to 1500°F), most of the cadmium in the waste stream will
be volatilized and discharged to the secondary chamber. At the
lower exhaust temperatures, the cadmium condenses onto small
particles and is exhausted as fine PM to the secondary chamber.
The primary chamber bottom ash, which may contain small
amounts of cadmium, is discharged via an ash removal system and
transported to a landfill for disposal. The ash removal system
may be either manual or mechanical. Typically, batch units and
smaller intermittent units employ manual ash removal. After the
system has shut down and the ash has cooled, the operator uses a
rake or... shovel^fcoremove, the ash and place it in a -drum -or- --- -
6-68
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dumpster. Some intermit tent-duty MWI's and all continuously
operated MWI's use a-mechanical ash removal system. The
mechanical system includes three major components: (i) a means
of moving the ash to the end of the incinerator hearth--usually
an ash transfer ram or series of transfer rams, .(2) a collection
device or container for the ash as it is discharged from the •
hearth, and'(3) a transfer system-to move the ash from the
collection point. Generally, these automatic systems are
designed to minimize fugitive emissions. For example, one type
of collection system uses an ash bin sealed directly to the
discharge chute or positioned within an air-sealed chamber below
the hearth. A door or gate that seals the chute is opened at
regular intervals to allow the ash to drop into the collection
bin. When the bin is filled, the seal-gate is closed, and the
bin is removed and replaced with an empty bin. in another
system, the ash is discharged into a water pit. The ash
discharge chute is extended into the water pit so that an air
seal is maintained. The water bath quenches the ash as the ash
is collected. A mechanical device, either a rake or drag
conveyor system, is used to intermittently or continuously remove
the ash from the quench pit. The excess water is allowed to
drain from the ash as it is removed from the pit, and the wetted
ash is discharged into a collection container.
The potential for cadmium emissions from both mechanical and
manual ash discharge systems is minimal. As described above,
most mechanical systems have seals and provide ash wetting as
described above to minimize fugitive PM emissions. While manual
systems can generate substantial fugitive PM, the concentrations
of cadmium have generally been shown to be quite low.69
Consequently, fugitive cadmium emissions are negligible.
Almost all the cadmium that enters the primary chamber is
_exhausj:ed_t.o_the_secondary^chamber as fine PM, although a small
6-69
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fraction may be partitioned with the ash. The primary function
of the secondary chamber is to complete the combustion of .the
volatile organic compounds that was initiated in the primary
chamber. Because the temperatures in the secondary chamber are
typically 980°C (1800°F) or greater, essentially all of the
cadmium that enters the secondary chamber will be exhausted as
fine EM. The hot exhaust gases from the secondary chamber may
pass through an energy recovery device (waste heat boiler or air-
to-air heat exchanger) and an air pollution control system before
they are discharged to the atmosphere through the combustion
stack. This combustion stack is the major route of cadmium
emissions from MWI's.
6.7.2 Emission Control Measures69 . .
A number of air pollution control system configurations have
been used to control PM and gaseous emissions from the MWI
combustion stacks. Most of these configurations fall within the
general classes of wet systems and dry systems. Wet systems
typically comprise a wet scrubber designed for PM control
(venturi scrubber or rotary atomizing scrubber) in series with a
packed-bed scrubber for acid gas removal and a high-efficiency
mist elimination system. Most dry systems use a fabric filter
for PM removal, but ESP's have been installed on some larger
MWI's. These dry systems may use sorbent injection via either '
dry injection or spray dryers upstream from the PM device to
enhance acid gas control. More detailed descriptions of MWI air
pollution control systems can be found in Reference 69. The
emission data presented in the section below provide information
on the performance of some of the more common systems.
6-70
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6.7.3 Missions70-87
The primary source of emissions from medical waste
incineration is the combustion gas exhaust stack. However, small
quantities of cadmium may be contained in the fugitive PM
emissions from ash handling operations, particularly if the fly.
ash is collected- in a dry air pollution control system with high
cadmium removal efficiencies.
Over the past 5 years, cadmium emissions have been measured
at several MWI's through the U. S. EPA's regulatory development
program, the MWI emission characterization studies conducted by
the State of California, and compliance tests conducted in
response to State air toxic requirements. -Emission data from
25 MWI's were identified in developing this L&E document.
However, only the data from 18 facilities were considered
adequate for emission factor development. For the other
facilities, either process data were insufficient to develop
emission factors or the test methodologies were considered
unacceptable. Emission data for the 18 facilities are tabulated
in Appendix B, Table B-4. The paragraphs below summarize the
information on uncontrolled emissions and on the performance of
emission control systems collected from these 18 facilities.
The uncontrolled emission data collected at 13 facilities
show substantial variability, with cadmium emission factors
ranging from 0.12 to 22 g/Mg of waste charged (2.4 x 10'4 to
4.4 x 10-2 lb/ton).70-78,81,84-87 ^^ dafca repregent a variety
of waste types (mixed'medical waste, red bag [infectious] waste
only, and pathological waste) and a variety of incinerator types -
(continuous and intermittent units with varied operating
practices). While the data are insufficient to demonstrate a
direct relationship between waste characteristics and emissions,
the data_^trqngly_.suggest that .most-of this variability is
... . 6-71
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related to differences in the cadmium content of the waste.-
First, characterization of the bottom ash at several facilities
showed little cadmium in. the ash, indicating that most of the
cadmium in the."waste is discharged with the combustion gases.
Second, as part of an EPA study, wastes from two different
hospitals were fired to the same incinerator under comparable
operating conditions. There was an almost threefold difference
in the average emission factors for the two wastes, with wastes
from the smaller hospital yielding an emission factor of "
1.6 g/Mg (3.1 x 10~3 Ib/ton) and those from the larger hospital
yielding a factor of 4.4 g/Mg (8.8 x 10'3 Ib/ton), again
providing evidence of waste-related variation. Although there
has been some speculation that the higher emission factors result
from having cadmium-bearing items, such as batteries and
pigments, in the waste stream, insufficient information is
available to define conclusively the influence of waste
attributes on cadmium emissions.
• Because emissions are strongly related to waste
characteristics, separate uncontrolled emission factors were
developed for the different waste types. These emission factors
are summarized in Table 6-21. Substantially greater information
is available for mixed medical waste incineration than for dither
red bag or pathological waste incineration. Consequently, the
mixed waste results are considered to be a. more reliable
indicator of the range of emission factors likely to be found
across the MWI population than are the red. bag or pathological
results. However, because the range in emission factors is so
large, even the mixed waste emission factors should be applied to
individual MWI's with caution.
The emission factors for the red bag and pathological waste
should be-used with extreme caution because each factor is based
on results from waste fireji at only one facility. Two
6-72
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TABLE 6-21. SUMMARY OF UNCONTROLLED CADMIUM EMISSION FACTORS
FOR MEDICAL WASTE INCINERATORS
Waste type
Mixed3
Red bagb
Pathological0
No. of
facilities
13
1
1
No. of
test runs
72
9
6
Cadmium emission factors,
g/Mg (1(T3 Ib/ton) waste
Range
0..12-22
(0.24 - 44)
0.72 - 2.5
(1.4-5.0)
<0.0 - 4.7
«0.0-9.3)
Mean
2.5
(5.0)
1.6
(3.3)
0.90
(1.8)
Source: References 70 - 78, 81, 84 - 87.
aBased on the range of facility averages. Number of runs for each facility ranged from
2 to 16.
Based on the range spanned by three test averages (each test comprised three runs) at one
facility.
°This emission factor is strongly influenced by a single large value. A better estimate of emissions
from a "typical" facility is the trimmed mean, which is 0.18 g/Mg (0.37 x 10~3 Ib/ton).
observations are noteworthy in interpreting these data. First,
although the red bag emission factor of 1.6 g/Mg
(3.3 x 10'3 Ib/ton) is within the range of emission factors for
mixed medical waste, the wastes were generated by the same
facility that had one of the largest mixed waste emission
factors. Therefore, the red bag emission factor may be
misleading. Similarly, the emission factor for pathological
waste of 0.90 g/Mg (1.8 x 10'3 Ib/ton) is near the bottom end of
the mixed waste range and could be even lower because it is
strongly influenced by a single large value (4.7 g/Mg
[9.3 x 10~3 Ib/ton]). This value is a factor of 20 larger than
the second largest value. If the largest and smallest values are
removed, the trimmed mean is 0.18 g/Mg (0.37 x 10~3 Ib/ton),
which' is similar to the median of the data. Hence, the emission
factor..Pf.._P_il8 3/Mg (0.37.x 1Q13_. lb/tonl._ia_recoimnended as the
6-73
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beat emission factor for a typical MWI firing pathological waste.
However, this low emission factor also may be misleading because
tests at the same facility produced .the lowest mixed waste
emission factor. As evidenced by these observations,, the red bag
and pathological emission data are too sparse to differentiate
effectively between the effects of waste type and
facility-specific waste practices on cadmium emissions.
Substantially fewer data are available on controlled
emissions than on uncontrolled emissions.72'73'77-83,85,87 The
best data available are those which characterize the performance
of seven MWI air pollution .control systems — a wet scrubber
system, a venturi scrubber system, a venturi scrubber/packed-bed
system, a duct sorbent injection/electrostatic precipitator
system, a fabric filter system, a dry injection/fabric filter
system, and a spray dryer/fabric filter system. Table 6-22
presents controlled emission factors and cadmium emission control
efficiencies for these air pollution control systems. Because
controlled emission factors could only be developed for a few
facilities, they are not likely to represent the variability
across the incinerator population. Therefore, it, is recommended
that controlled emission factors be developed by applying the
average control efficiencies to uncontrolled emission factors or
emission rates rather than using the controlled emission factors
presented in Table 6-22.
The performances of two of the dry systems (dry
injection/fabric filter and spray dryer/fabric filter) were
examined with and without carbon injection. The results from
these tests and from the test of the fabric filter with no carbon
injection are presented in Table B-4, Appendix B. These results
indicate that the dry systems without carbon injection provided
greater than 99 percent control of cadmium. For these systems,
the outlet cadmium emissions range from 99.1 percent to
6-74
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6-75
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99.9 percent lower than the inlet emissions. This variability is
considered to be well within the normal range of process and
emission test method variability as described in Section 9.
Consequently, the results are consistent with essentially
complete removal by the control system. The dry systems with . •
carbon injection achieve essentially the same cadmium removal as
those systems without carbon injection, with control efficiencies
ranging from 97.3, percent to 99.9 percent.
The emission test results for the wet systems are also •
presented in Table B-4, Appendix B. As shown in Table 6-22, the
performance of the wet systems in controlling cadmium emissions
was not as effective as that achieved by the dry systems with or
without carbon injection. For the wet systems, the outlet
cadmium emissions range from 160 percent higher to 49 percent
lower than the inlet emissions. Table 6-23 presents the best
typical uncontrolled emission factors for MWI's. To obtain best
typical controlled emission factors for venturi scrubber/packed
bed systems, apply a 38-percent efficiency to these uncontrolled
emission factors. For dry systems with or without carbon
injection, apply a 97-percent efficiency to these uncontrolled
emission factors.
TABLE 6-23. BEST TYPICAL UNCONTROLLED CADMIUM EMISSION FACTORS
FOR MEDICAL WASTE INCINERATORS
Waste type
Typical cadmium emission factors
g/Mg waste
10"3 Ib/ton waste
Mixed
2.5
5.0
Red Bag
1.6
3.3
Pathological
0.18
0.37
6-76
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SECTION 7
EMISSIONS FROM NONFERROUS SMELTING/REFINING
Cadmium is emitted from various nonferrous smelting and
refining operations including the following:
1.
2.
3.
process,
4.
process;
5.
6.
' 7.
Primary lead smelting;
Primary copper smelting;
Primary zinc smelting and refining--electrolytic
Primary zinc smelting and refining--electrothermic
Secondary copper smelting and refining;
-Secondary zinc recovery from metallic scrap; and
Secondary zinc recovery from steel production.
Feed materials processed at the facilities listed above
include minerals and ores extracted from the earth (primary
smelting), as well as scrap metal from a variety of sources
(secondary smelting). These feed materials contain cadmium. At
various stages of manufacturing, the feed materials are processed
at elevated temperatures, thereby releasing cadmium emissions.
This section presents process information, air pollution control
measures, and estimates of cadmium emissions from these sources.
7.1 PRIMARY LEAD SMELTING
Lead is recovered from a sulfide ore, primarily galena (lead
sulf ide [PbS] ) , which also contains small amounts of copper-,
data
7-1
-------
source has reported- that the cadmium content in lead ore is
approximately 0.02 percent.88
A lis't of primary lead smelters currently in operation
within the United States (U.S.) is given in Table 7-1."
TABLE 7-1.- DOMESTIC PRIMARY LEAD .SMELTERS AND REFINERIES
Smelter
Refinery
1990 Production, Mg (tons)
ASARCO, East Helena, MT
ASARCO, Omaha, NE
65,800 (72,500)
ASARCO, Glover, MO
Same site
112,000 (123,200)
Doe Run (formerly St. Joe),
Herculaneum, MO
Source: Reference 89.
Same site
231,000 (254,100)
A description of the process used to manufacture lead and a
discussion of the emissions resulting from the various operations
are presented below.
7.1.1 Process Description9**
Figure 7-1 contains a process flow diagram for primary lead
smelting. The recovery of lead from the lead ore consists of
three main steps: sintering, reduction, and refining.
11 i|lll: i"! ' i
1 ! ' .1
Sintering is carried out in a sintering machine, which is a
continuous steel pallet conveyor belt. Each pallet consists of
perforated grates, and beneath the grates are wind boxes, which
are connected to fans to provide a draft through the moving
sinter charge. The sintering reactions take place at about
1000'C (1832'F) during-which lead sulfide is" converted to lead
oxide. Since cadmium boils at approximately 767«C (1415°F), most
7-2
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of the cadmium in the ore can be expected to be emitted during
sintering.
Reduction"of the sintered lead is carried out in a blast
furnace at a temperature of 1600°C (2912"F). The furnace is
charged with a mixture of sinter (80 to 90 percent of charge);
metallurgical coke (8 to 14-percent of charge); and other
materials, such as limestone, silica, litharge, and unspecified
constituents which are balanced to form a. fluid slag. In the
blast furnace, the sinter is reduced to lead. The level of heat
needed to create the reaction is supplied by coke combustion.
•Slag, consisting of impurities,, flows from the furnace and is
either land deposited or is further processed to recover zinc.
The impurities include arsenic, antimony, copper and other metal
sulfides, iron, and silicates. Lead bullion, which is the
primary product, undergoes a preliminary treatment to remove
impurities, such as copper, sulfur, arsenic, antimony, and
nickel. The majority of the cadmium in the original feed
material can be expected to be emitted during the reduction step.
Further refining of the lead bullion is carried out in cast iron
kettles. Refined leadr which is 99.99 to 99.'999 percent pure, is
cast into pigs for shipment.
7-1-2 Emission Control Measures90
Cadmium emission sources are indicated in Figure 7-i by
solid circles. Emission controls on lead smelter operations are
used for controlling particulate matter (EM) and' sulfur dioxide
(S02) emissions resulting from the blast furnace and sintering
machines. Centrifugal collectors (cyclones) may be used in
conjunction with fabric filters or electrostatic precipitators
(ESP's) for PM control. Because cadmium emissions generally will
be associated with participates, most of the cadmium will
potentially condense in the cyclone. Thus, a high degree of
7-4
-------
control of cadmium emissions may be achieved in the fabric filter
or ESP. However, no data on the effectiveness of fabric filters
and ESP's in controlling cadmium emissions are available.
Control of SO2 is achieved by absorption to form sulfuric
acid in the sulfuric acid plants, which are commonly part of lead
smelting plants. ' •'.'•%
7.1.3 Emissions
Cadmium, which may exist in the ore at a 0.02-percent
concentration, can potentially be emitted when temperatures reach
high levels in the sintering and reducing steps. Because the
sintering step is carried out at temperatures much higher than
the boiling point of cadmium, the sintering step is considered to
be the primary source of cadmium emissions. Table 7-2 presents
estimates of cadmium emissions reported by three facilities
during 1990, as required under Superfund Amendments and
Reauthorization Act (SARA) Title III regulations.7
TABLE 7-2. PRIMARY LEAD PRODUCERS REPORTING CADMIUM EMISSIONS IN THE
1990 TOXICS RELEASE INVENTORY
Smelter
Emissions, kg (Ibs)
Nonpoint
Point
Total
ASARCO Inc., Glover. MQ
111 (245)
415 (914)
526 (1,159)
ASARCO Inc., East Helena. MT
3,175 (7.00Q1.
4,990 (11.000)
8,165 (17.9631
Doe Run, Herculaneum, MO
Source: Reference 7.
Test data pertaining to cadmium emissions from the various
operations are not available. Table 7-3 presents cadmium
emission factors reported in the EPA data base, SPECIATE, for
.Ya-?.ious .0Perations during primary lead smelting.^ Because..the
7-5
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TABLE 7-3. CADMIUM EMISSION FACTORS FOR LEAD-SMELTING FACILITIES
Emission source
Source
classification
code (SCO
Cadmium emission factor3
Ib/ton
kg/Mg
1 Sintering: single stream
I Blast furnace operation
1 Dross raverberatory furnace
I Ore crushing
fSfntering; dual stream feed end
30301001
30301002
30301003
30301004
30301006
1.39941
41.74965b
0.2438b
0.01668°
9.67987b
0.7°
20.9b
0.1219b
0.00834°
I Slag fume furnace
1 Lead dressing
I Raw material crushing and grinding
I Raw material unloading
I Raw material storage piles
30301008
30301009
30301010
30301011
30301012
0.00359d
0.00203d
0.04553d
0.003346
0.00258
0.0018d
0.001d
0.023d
0.00167s
0.00125e
I Raw material transfer
II Sintering charge mixing
I Sinter crushing/screening
ISinter transfer
|S?nter fines return handling
30301013
30301014
30301015
30301016
30301017
0.00417e
0.01 S85e
0.06829f
0.00911f
0.40977f
0.00209s
0.00943s
0.03415f
0.00456f
0.2049f
I Blast furnace tapping (metal and slag)
I Blast furnace lead pouring
I Blast furnace slag pouring
iLead refining/silver retort
(Lead casting
30301019
30301020
30301021
30301022
30301023
0.00728d
0.04234d
0.00075d
0.08195d
0.03961d
0.00364d
0.02117d
0.00038d
0.04098d
0.0198d
Reverberatory or kettle softening
1 Sinter machine leakage
1 Sinter dump area
30301024
30301025
30301026
0.13659d
0.02519f
0.00046f
0.0683d
0.0126f
0.00023f
Source: Reference 91.
aAII emission factors are reported as found in the SPECIATE data base without rounding off
(Reference 91). Emission factors in SPECIATE data base are reported in Ib/ton of process
sctivi'ty*
blb/ton (kg/Mg) of concentrated ore.
clb/ton (kg/Mg) of ore crushed. • "
dlb/ton (kg/Mg) of lead product.
8lb/ton (kg/Mg) of raw material.
flb/ton (kg/Mg) of sinter.
7-6
-------
validity of these emission factors cannot be verified, extreme
caution should be exercised when using these factors.
7.2 PRIMftRY COPPER SMELTING
The principal method for recovering copper from sulfide ore
is. pyrometallurgical smelting. Copper ores contain small
quantities of arsenic, cadmium, lead, antimony, and other heavy
metals. One data source has reported that cadmium content in
copper ore is approximately 0.01 percent.88
A list of primary copper smelters currently operating within
the U.S. is given in Table 7-4.92 A description of the process
used to manufacture copper and a discussion of the emissions
resulting from the various operations are presented below.
TABLE 7-4. DOMESTIC PRIMARY COPPER SMELTERS AND REFINERIES
Smelter
1992 Capacity, Mg (tons)
ASARCO Inc., Hayden, AZ
191,000 (210,000)
Cyprus Miami Mining Co., Globe, AZ
180,000 (198,000)
MAGMA Copper Co., San Manuel, AZ
290,000 (319,000)
Copper Range Co., White Pine, Ml
60,000 (66,000)
Phelps Dodge, Hidalgo, NM
190,000 (209,000)
Chino Mines Co., Hurley, NM
170,000 (187,000)
ASARCO Inc., El Paso, TX
100,000 (110,000)
Kennecott, Garfield, UT
210,000 (231,000)
ASARCO Inc., Amarillo, TX
Unknown
Phelps Dodge, B Paso, TX
Unknown
Source: Reference 92.
7-7
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7.2.1 Process Description90
The pyrometallurgical copper-smelting process is illustrated
in Figure '7-2. "The traditionally used process includes roasting
ore concentrates to produce calcine, smelting of roasted (calcine
feed) or unroasted (green feed) ore concentrates to produce ...
matte, and converting the matte to yield blister copper product
(about 99 percent pure). Typically, the blister copper is
refined in an anode furnace, cast into "anodes", and then sent to
an electrolytic refinery for further impurity elimination. The
currently used copper smelters process ore concentrates by drying
them in fluidized bed dryers and then converting and refining the
dried product in the same manner as the traditionally used
process.
In roasting, charge material of copper concentrate, mixed
with a siliceous flux (often a low grade ore)', is heated in air
to about 650°C (1200'F), eliminating 20 to 50 percent of the
sulfur as SO2. Portions of such impurities'as antimony, arsenic,
and lead are driven off, and some iron is converted to oxide.
The roasted product, calcine, serves as a dried and heated charge
for the smelting furnace. Either multiple-hearth or fluidized-
bed roasters are used for roasting copper concentrate.
Multiple-hearth roasters accept moist concentrate, whereas
fluidized-bed roasters are fed finely ground material (60 percent
minus 200 mesh). With both of these types, the roasting is
autogenous. Because there is less air dilution, higher SO2
concentrations are present in fluidized-bed roaster gases than in
multiple-hearth roaster gases. Because cadmium has a boiling
point of 767°C (1415°F), most of the cadmium in the ore may
remain in the calcine, instead of being emitted as an air
pollutant during roasting.
7-8
-------
Ore Concentrates with Silica Fluxes
Fuel
Air
ROASTINGa
ORDRYINGb
•3
o
£
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Fuel
Air
OFF GAS
FLASH
SMELTING
Slag to Dump
(0.5% Cu)
Air
OFF GAS
MATTE (-40% Cu)
CONVERTING
Natural or Reformulated Gas
Green Poles or Logs
Fuel
Air
Slag to Converter
OFF GAS
Blister Copper (98.5% Cu)
FIRE REFINING
J
OFF GAS
Denotes potential
cadmium omission source
Anode Copper (99.5% Cu)
To Electrolytic Refinery
jjFiret step in the traditionally used copper-smelting process.
"First step in the currently used copper-smeftirtg process.
Rgure 7-2. Typical primary copper-smelting process.90
7-9
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In the smelting process, either hot calcines from the
roaster or raw unroasted or dried concentrates are melted with
siliceous flux in a flash smelting furnace to produce copper
matte, a molten mixture of cuprous sulfide (Cu2s), ferrous
sulfide (FeS) and some heavy metals. The required heat comes
from partial oxidation of the sulfide charge' and from burning'
external fuel. Most of the iron and some, of the impurities in
the charge oxidize with the fluxes to form a. slag on top of the
molten bath; this slag is periodically removed and discarded.
Copper matte remains in the furnace until tapped. Mattes
produced by the domestic industry range from 35 to 65 percent
copper, with 45 percent being the most common. The copper
content percentage is referred to as the matte grade. Currently,
five smelting furnace technologies are used in the U.S.:
reverberatory, electric, Noranda/ Outokumpu (flash), and Inco ""
(flash). Reverberatory furnaces may operate at temperatures as
high as 1500°C (2732°F), while flash furnaces may operate at
temperatures of 1200 to 1300°C (2200 to 2300«F). Even though the
exact temperatures at which the other two'furnace technologies
(electric and Noranda) operate are not known, • it is probable that
they operate at temperatures .higher than the boiling point of
cadmium. Therefore, most of the cadmium that remains in the
calcine may be emitted as an air pollutant during the smelting
step.
i
I
Reverberatory furnace operation is a continuous process, '
with frequent charging of input materials and periodic tapping of
matte and skimming of slag. Heat is supplied by combustion of
oil, gas or pulverized coal, and furnace temperatures may exceed
1500°C (2732°F).v Currently, a reverberatory furnace used at
ASARCO, El Paso, and-an IsaSmelt furnace at Cyprus, are being
replaced with ConTop cyclone reactors (another type of flash
smelting).
7-10
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For smelting in electric arc furnaces, heat is generated by
the flow of an electric current in carbon electrodes. These -
electrodes are lowered through the furnace roof and submerged in
the slag layer-of the molten bath. The feed generally consists
of dried concentrates or calcines; charging wet concentrates is
avoided. The chemical and physical changes" occurring in the
molten bath are -similar to those occurring in .the molten bath of
a reverberatory furnace. Also, the matte and slag-tapping
practices are similar at both furnaces. Electric furnaces do not
produce fuel combustion gases, so flow rates are lower and S02
concentrations are higher in the effluent gas of electric
furnaces than in the effluent gas of reverberatory furnaces.
Flash furnace smelting combines the operations of roasting
and smelting to produce a high-grade copper matte from
concentrates and flux. In flash smelting, dried ore concentrates
and finely ground fluxes are injected, together with oxygen,
preheated air, or a mixture of both, into a furnace -of special
design where temperature is maintained at approximately
1200 to 1300-C (2200 to 2300«F). In contrast to reverberatory
and electric furnaces, most flash furnaces use the heat generated
from partial oxidation'of their sulfide- charge to provide much or
all of the energy (heat) required for smelting. They also
produce offgas streams containing high concentrations of SO2.
Other flash ..furnaces such as ConTop cyclone reactors use oxyfuel
combustion to generate the heat required for oxidation.
Slag produced by flash furnace operations typically contains
higher amounts of copper than is found-in reverberatory or
electric furnace operations. As a result, the flash furnace and
converter slags are treated in a.slag-cleaning furnace to recover
the copper (not conducted at the ASARCO, Hayden facility). Slag-
cleaning furnaces usually are small electric furnaces. The flash
converter alags_ are charged to a slag-cleaning
7-11
-------
furnace and are allowed to settle under reducing conditions,, with
the addition of coke or iron sulfide. The copper, which is in
the oxide form in the slag, is converted to copper sulfide. The
copper sulfide.is subsequently removed from the furnace and is
charged to a converter with regular matte.. If the slag's copper
content is low, the slag is discarded.
The Noranda process, as originally designed, allowed the
continuous production of blister copper in a single vessel by
effectively combining roasting, smelting and converting into one
operation. "Metallurgical problems, however, led to the operation
of these reactors for the production of copper matte. As in
flash smelting, the Noranda process takes advantage of the heat
energy available from the copper ore. The remaining thermal
energy requirement is supplied by oil burners, or by coal mixed
with the ore concentrates.
The final step in blister copper production is conversion.
This step eliminates the remaining iron and sulfur present in the
matte and leaves behind only the molten "blister" copper. All
but one U.S. smelter uses Fierce-Smith converters, which are
refractory-lined cylindrical steel shells mounted on trunnions at
either end, and rotated about the major axis for charging and
pouring. An opening in the center of the converter functions as
a mouth through which molten matte, siliceous flux, and scrap
copper are charged, and gaseous products are vented. Air or
oxygen-rich air is blown through the molten matte. Iron sulfide
(FeS) is oxidized to iron oxide (FeO) and S02, and the blowing
and slag-skimming steps are repeated until an adequate amount of .
relatively pure Cu2S, called "white metal,™ accumulates in the
bottom of the converter. A renewed air blast then oxidizes the
copper sulfide sulfur to S02, leaving blister copper in the
converter. The blister copper is subsequently removed and - - -
transferred to refining facilities. This segment of converter
7-12
-------
operation is termed the finish blow. -The SO2 produced throughout
the operation is vented to pollution control devices.
One domestic smelter uses Hoboken converters. The Hoboken
converter is essentially like a conventional Pierce-Smith
converter, except that this vessel is fitted- with a side flue at
one end, which is shaped, as an inverted U. This flue arrangement
permits siphoning of gases from the interior of the converter
directly into the offgas collection system. This leaves the
converter mouth under a slight vacuum. The Hoboken converters
are also equipped with secondary hoods to further control '
emissions.
Blister copper usually contains from 98.5 to 99.5 percent
pure copper. Impurities may include gold, silver, antimony,
arsenic, bismuth, iron, lead, nickel, selenium, sulfur,
tellurium, and zinc. To purify blister copper further, fire
refining and electrolytic refining are used. In fire refining,
blister copper is placed in an anode furnace; a flux is usually
added, and air is blown through the molten mixture to oxidize
remaining impurities, which are removed as a slag. The remaining
metal bath is subjected to a reducing atmosphere, which
reconverts cuprous oxide to copper. The temperature in the
furnace is around HOO°C (2012°F). The fire-refined copper is
then cast into anodes. Electrolytic refining separates the
copper from impurities by electrolysis in a solution containing
copper sulfate and sulfuric acid. Metallic impurities
precipitate from the solution and form ,a sludge that is removed
and treated to recover precious metals. Copper is dissolved from
the anode and deposited at the cathode. Cathode copper is
remelted and cast, into bars, rods, ingots or slabs for marketing
purpose. The copper produced is 99.95 to 99.97 percent pure.
Any residual cadmium that has not been emitted during the
smelting step may be emitted during the refining step.
7-13
-------
7.2.2 Emission Content, Measures90
Cadmium emission sources are indicated in Figure 7-2 by
solid circles.- Emission controls on copper smelters are used for
controlling PM and SO2 emissions resulting from roasters,
smelting furnaces, and converters. Electrostatic precipitators
are the common PM control devices employedat copper-smelting
facilities. '
Control of SO2 emissions is achieved by absorption to
sulfuric acid in the sulfuric acid plants/ which are commonly
part of copper-smelting plants.
7.2.3 Emissions
Cadmium, which is present in the ore, can potentially be
emitted from smelting furnaces and converters. Table 7-5
presents estimates of cadmium emissions reported by three
facilities during 199O7.
TABLE 7-5. PRIMARY COPPER PRODUCERS REPORTING CADMIUM EMISSIONS
IN THE 1990 TOXICS RELEASE INVENTORY
Smelter
ASARCO Inc., El Paso, TX
Emissions, kg (Ibs)
Nonpoint
771 (1,696)
Point
3,048 (6,706)
Total
3,819 (8,402)
ASARCO Inc., Hayden, AZ
113 (249)
1,203 (2,652)
Kennecott, Garfieid, UT
Note: Cypress Miami Mining Co., Globe, AZ, reported zero cadmium emissions in the 1990 TRI
No other facilities reported emissions.
Source: Reference 7.
7-14
t
-------
Test data pertaining to cadmium emissions from primary
copper facilities are limited. One emission test report at
Copper Range Company, located in .White Pine, MI, contains results
of metals -analysis and was reviewed during this study.93 This
facility operates a reverberatory furnace that is controlled by
an ESP. The exhaust stream from the converter '(which is
uncontrolled), is mixed.' with the exhaust.. from, the ESP. outlet and
is routed through the main stack and discharged into the
atmosphere. Testing for metals was performed at the main stack
after two exhaust.streams (from the ESP outlet and the converter)
were mixed. Cadmium emissions were measured for three modes of
converter operation: slag-blow, copper-blow, and converter idle
(no blow) cycles. The cadmium level during the slag-blow cycle
was measured to be the highest, corresponding to a cadmium
emission rate of 2.3509 Ib/hr. Additionally, the plant capacity
was reported to be approximately 42 tons/hr of feed, which •
consists of mill concentrate, limestone, iron pyrites, and
recycled material. The actual process rate during the test is
not known. Since the feed mix varies from facility to facility,
the cadmium emissions measured at Copper Range Co. cannot be-used
to estimate a general cadmium emission factor that would be valid
on an industrywide basis. Additionally, Copper Range Co., is the
only facility in the U.S. that operates a reverberatory furnace.
All other copper-smelting facilities use flash furnaces which
inherently produce less emissions.
The only available emission factor data are from the
SPECIATE data base. Table 7-6 presents cadmium emission factors
for various emission points at primary copper-smelting facilities
as reported in the SPECIATE data base.91 Because the-validity of
these emission factors cannot be verified, extreme caution should
be exercised when using these factors.
7-IS
-------
TABLE 7-6. CADMIUM EMISSIONS FROM PRIMARY COPPER PRODUCTION
Emission source
Reverberatory smelting furnace after roaster-ESP
Convenor (all configurations)-ESP
Rre (furnace) refining-ESP
Ore concentrate dryer— ESP
Reverberatory smelting furnace with ore charging
(without roasting)-ESP
Fluidized-bed roaster— ESP
Electric smelting furnace— ESP
^ash smelting
toasting: fugitive emissions-ESP
Reverberatory furnace: fugitive emissions-ESP
Convenor: fugitive emissions
Anode refining furnace: fugitive emissions— ESP
Slag-cleaning furnace: fugitive emissions-ESP
Slag-cleaning furnace— ESP
AFT MHR + RF/FBR + EF
Ruidized-bed roaster with reverberatory furnace +
convenor-ESP
Concentrate dryer with electric furnace, cleaning
furnace and convenor— ESP
Concentrate dryer with flash furnace and
convenor-ESP
Source
classification
code (SCO
30300503
30300J504
303005505
30300506
30300507
30300509
30300510
30300512
30300513
30300514
30300515
30300516
30300517
30300522
30300524
30300525
30300526
30300527
Cadmium
emission factor3
Ib/ton
0.005
Q-.0036
0.001
0.001
0.005
0.0055
0.01
2.3128
0.00026
0.0071 6
0.02829
0.00005
0.0008
0.001
0.18
0.0055
0.001
0.001
kg/Mg
0.0025
0.0018
0.0005
0.0005
0.0025
0.00275
0.005
1.1564
0.00013
0.00358
0.014145
0.000025
0.0004
0.0005
0.09
0.00275
0.0005
0.0005
Source: Reference 91.
aAII emission factors are reported as found in the SPEC1ATE data base without rounding off
(Reference 91). All emission factors reported above are in the units of Ib/ton of concentrated ore.
7-1S
-------
7.3 PRIMARY ZINC SMELTING AND REFINING
Zinc is found primarily as the sulfide ore, sphalerite
(ZnS). Its common coproduct ores are lead and copper. Metal
impurities commonly associated with ZnS are cadmium (from 0.2 to
0.4 percent94) and minor quantities of germanium, gallium,
indium, and thallium. Zinc ores typically contain from 3 to
11 percent zinc. Some ores,- containing as little as 2 percent,
are recovered. Concentration at the mine brings this to 49 to
54 percent zinc, with approximately 31 percent free and
uncombined sulfur.90
A list of primary zinc smelters currently in operation
within the U.S. is given in Table 7^7.95 zinc ores are processed
into metallic slab zinc by two basic processes. Three of the
four domestic U.S. zinc-smelting facilities use the electrolytic '
process, and one plant uses a pyrometallurgical smelting'process,
which is typical of the primary nonferrous smelting industry.
The plant that uses the. pyrometallurgical process provides energy
by electric resistance heating. Therefore, in this case, the
pyrometallurgical process is referred to as the electrothermic
process. A description of the process used to manufacture zinc
by .the electrolytic and electrothermic processes and a discussion
of the emissions resulting from the various operations are
presented below.
7-3.1 Process Description - Slectrolyf-I
,90
A general diagram of the electrolytic and electrothermic
processes is presented in Figure 7-3. Electrolytic processing
involves four major steps: roasting, leaching, purification, and
electrolysis.
7-17
-------
TABLE 7-7. DOMESTIC PRIMARY ZINC PRODUCERS
Company
Type of process
1992 slab zinc production
capacity, Mg (tons)
Big River Zinc Co., Sauget, IL
Electrolytic
82,000 (90,200)
Jersey Miniers Zinc Co.,
Clarksville, TN
Electrolytic
98,000 (107,800)
Zinc Corporation of America,
Bartiesvilie, OK
Electrolytic
51,000 (56,100)
Zinc Corporation of America,
Monaca, PA
Electrothermic
123,000 (135,300)
Source: Reference 95.
Roasting is a process common to both electrolytic and
pyrometallurgical processing. Calcine is produced by the
roasting reactions in any one of three different types of
roasters: multiple-hearth, suspension, or fluidized-bed.
Multiple-hearth roasters are the oldest type used in the United
States, while fluidized-bed roasters are the most modern.
Fluidized-bed roasters are currently .the only type of roasting
process used in the United States. The primary zinc-roasting
reaction occurs between 640° and 1000°C (1184° and 1832°F),
depending on the type of roaster used. The reaction is:
2ZnS
30-
-> 2ZnO
2S02
(1)
In a multiple-hearth roaster, the concentrate is blown
through a series of nine or more hearths stacked inside a brick-
lined cylindrical column. As the feed concentrate drops through
the furnace, it is first dried by the hot gases passing through.
the hearths and then oxidized to produce calcine. The reactions
are slow and can only be sustained by the addition of fuel
I ..JJ'HILJBI ""I"1""I'LS'f "II 1Ul!!"!l!H". 1
7-ia
-------
O
DC
LU
O
DC
O
LU
_J
LU
O
O
DC
O
LU
—I
LU
c
O
IM
8
_ra
CD
•a
0)
O
cn.
00
05
CO
o
o
CD
CO
c
re
S
to
o
r^
CO
i_
CD
7-19
-------
In a suspension roaster, the feed is blown into a combustion
chamber, which is very similar to that of a pulverized coal
furnace. Additional grinding, beyond that required for a
multiple -hearth furnace, is normally required to assure that heat
transfer to the material is fast enough to initiate
desulfurization and oxidation reactions in 'the furnace chamber,
Hearths at the bottom of the roaster capture the larger
particles, which need more 'time in the furnace to complete the
desulfurization reaction.
i y ''
In a fluidized-bed roaster, finely ground sulfide
concentrates are suspended -and oxidized within a pneumatically
supported feedstock bed. This technique achieves the lowest
sulfur content calcine of the three roaster designs.
Suspension and fluidized-bed roasters are superior to the
multiple hearth for several reasons. Although they emit more
particulate, their reaction rates are much faster, allowing
greater process rates. Also, the SO2 content of the effluent
streams of these two roasters is significantly higher, permitting
more efficient and economical use of acid plants to control SO2
emissions .
Cadmium has a boiling point of approximately 767 °C (1413°F)
Most of the cadmium (present in concentrates as cadmium sulfide)
is converted to the oxide along with zinc and many of the other
metals in preparing a calcine for leaching.
Leaching is the first step of electrolytic reduction. In
this step, the zinc oxide reacts with sulfuric acid to form
aqueous zinc sulfate in an electrolyte solution.
Zn°
H2S04 -
S04-2
(aq)
H20
'(2)
7-20
-------
Single and double leach methods can be used, although the
former exhibits excessive sulfuric acid losses and poor zinc
recovery. In double leaching, the calcine is first leached in a
neutral solution. The readily soluble sulfates from the calcine
dissolve, but only a portion of the zinc oxide enters the
solution. The calcine is then leached in the acidic electrolysis
recycle electrolyte. The. zinc oxide is^dissolved as shown in
reaction 2, as are many of the impurities, especially iron. The
electrolyte is neutralized by this process, and it serves as the
leach solution for the first stage of the calcine leaching. This
recycling also serves as the first stage of refining, since much
of the dissolved iron precipitates out of the solution.
Variations on this basic procedure include the use of
progressively stronger and hotter acid baths to bring as much of
the zinc into solution as possible.
Purification is a process in which a variety of reagents are
added to the zinc-laden electrolyte to force impurities to
precipitate. The solid precipitates -are separated from the
solution by filtration. The techniques that are used are among
the most advanced industrial applications of inorganic solution
chemistry. Processes vary from smelter to smelter, and the
details are proprietary and often patented. Metallic impurities,
such as arsenic, antimony, cobalt, germanium, nickel, and
thallium, interfere severely with the electrolyte deposition of
zinc and their final concentrations are limited to less than
0.05 milligrams per liter (4 x 10~7 pounds per gallon).
Electrolysis takes place in tanks, or cells, containing a
number of closely spaced rectangular metal plates, which act as .
anodes (made of lead with 0.75 to 1.0 percent silver) and as
cathodes (made of aluminum) . A series of three major reactions
occurs within the electrolysis cells:
7-21
-------
2H20
H2S04
anode
4H+(aq) > 4e~+O2
2Zn
+2
4e-
cathode
Zn
4H+(aq) + 2S04-2(aq)
-> 2H2S04
(3)
(4)
(5)
Oxygen gas is released at the anode; metallic zinc is
deposited at the cathode, and sulfuric acid is regenerated within
the electrolyte.
Electrolytic zinc smelters contain a large number of
cells, often several hundred. A portion of the electrical energy
released in these cells dissipates as heat. The electrolyte is
continuously circulated through cooling towers, both to lower its.
temperature and to concentrate the electrolyte through the
evaporation of water. Routinely, half of the cathodes in a cell
are disengaged for removal of zinc from the plates. The other
half of the cathodes carry a higher current load. Occasionally a
complete cell shutdown occurs, such as when a cell is by-passed
(using a Buss Bar to reroute current) for cleaning or repairing.
The final stage of electrolytic zinc smelting is the
melting and casting of the cathode zinc into small slabs,
27 kilograms (59 pounds), or large slabs, 640 to 1,100 kilograms
(1,408 to 2,420 pounds). Any cadmium vapors driven off in the
retorting furnace are collected along with the zinc vapors in the
zinc condenser.
7.3.2
Sintering is the first stage of the pyrometallurgical
reduction of zinc oxide to slab zinc. Sintering removes lead and
7-22
-------
cadmium impurities by volatilization and produces an agglomerated
permeable mass suitable for feed to retorting furnaces.
Downdraft sintering machines of the Dwight-Lloyd type are used in
the industry. .Grate pallets are joined together for a continuous
conveyor system. Combustion air is drawn down through the grate
pallets and is exhausted to a particulate control system. The
feed is a. mixture of calcine, recycled sinter, a»d.coke breeze
which is low sulfur fuel. Having a low boiling point, oxides of
lead and cadmium are volatilized from the sinter bed and are
recovered in the particulate control system. ' As described
earlier, most of the cadmium can be expected to be converted to
the oxide during the roasting step. Most of the cadmium would
therefore be emitted and recovered during the. sintering step.
» "
In retorting, because of the low boiling point of metallic
zinc, 906°C (1663°P), reduction and purification of zinc-bearing
minerals can be accomplished to a greater extent than with most
minerals. The sintered zinc oxide feed is brought into a high
temperature reducing atmosphere of 900° to 1499°C (1652° to
2730°F). Under these conditions, the zinc oxide is
simultaneously reduced and volatilized to gaseous zinc:
ZnO + CO —> Zn (vapor) +• CO-
Carbon monoxide regeneration also occurs:
CO, +'C -> 2CO
(6)
(7)
The zinc vapor and carbon monoxide that are produced pass
from the main furnace to a condenser where zinc recovery is
accomplished by bubbling the gas-mixture through a molten zinc
bath.
7-23
-------
Retorting furnaces can be heated either externally by
combustion flames or internally by electric resistance heating.
The latter approach, electrothermic reduction, is the only method
currently practiced in the United States, and it has greater
thermal efficiency than do external heating methods. In a retort
furnace, preheated coke and sinter, silica-and miscellaneous
zinc-bearing materials are fed continuously into the top of the
•furnace. Feed coke serves as the principal electrical conductor,
producing heat; it also provides the carbon monoxide required for
zinc oxide reduction. Further purification steps can be
performed on the-molten metal collected in-the condenser. The
molten zinc finally is cast into small slabs, 27 kilograms
(59 pounds), or the large slabs, 640 to 1,100 kilograms (1,408 to
2,42X3 pounds). Any cadmium vapors driven off in the retorting
furnace are collected along with the zinc vapors in the zinc
condenser.
7.3.3
Emission Contygl Measures90*96
Cadmium emission sources are indicated in Figure 7-3 by
solid circles. Emission controls used at electrolytic zinc
smelters include fabric filters for controlling PM from ore
storage and handling operations, and zinc-smelting operations.
Emission controls employed at electrothermic zinc smelters
include fabric filters for controlling PM from sinter machines,
sinter sizing and crushing operations, electrothermic furnace
preheatersv electrothermic furnaces, zinc-holding furnaces, and
zinc-refining columns.
Control of S02 emissions at both electrolytic and
electrothermic zinc smelters is achieved by absorption to
sulfuric acid in the sulfuric acid plants, which are commonly
part of zinc-smelting plants.
7-24
-------
7.3.4 Emissions
Cadmium, which is present in the ore, can potentially be
emitted from roasters (in both electrolytic and electrothermic
processes) and from sintering machines and retorting steps of the
electrothermic process. Table 7-8 presents estimates of cadmium
emissions reported by-the four facilities during 1990.7 The
only available emission factor data are from the SPECIATE data
base. Table 7-9 presents cadmium emission factors for various
emission points at primary zinc-smelting facilities as reported
in the SPECIATE data base.91 Because the validity of these
emission factors cannot be verified, extreme caution should be
exercised when using them.
TABLE 7-8.. PRIMARY ZINC PRODUCERS REPORTING CADMIUM EMISSIONS
IN THE 1990 TOXICS RELEASE INVENTORY
Company
Big River Zinc Co., Sauget, IL
Jersey Miniere Zinc Co.,
Clarksville, TN
Zinc Corporation of America,
Bartlesville, OKa
Zinc Corporation of America,
Monaca, PA
Type of process
Electrolytic
Electrolytic
Electrolytic
Electrothermic
Emissions, kg (Ib)
860 (1,892)
227 (499)
2,936 (6,459)
1,724 (3,793)
Source: Reference 7.
aThe only plant with secondary zinc processing facilities. ZCA states that greater than 98 percent
of the emissions result from the secondary zinc processing facility.
7.4 SECONDARY COPPER SMELTING AND REFINING
The secondary' copper industry processes scrap metals for
the recovery of copper. Products include refined copper or
copper alloys in forms such as ingots, wirebar, anodes, and shot.
7-25
-------
TABLE 7-9. CADMIUM EMISSIONS FROM PRIMARY ZINC PRODUCTION
Emission source
Multiple-hearth roaster*
Sinter strand
Vertical retort/electrothermal
furnace*
Electrolytic processor
Rash roaster*
Ruidized-bed roaster
Raw material handling and
transfer
Sinter breaking and cooling
Zinc casting
Raw material unloading
Source classification code
(SCO
30303002
30303003
30303005
30303006
30303007
30303008
30303009
30303010
3030301 1
30303012
Source: Reference 91.
Cadmium
emission factor3
Ib/ton
4.98492b
1 .9764b
0.00008b
0.065885
43.92b
47.5873b
0.08784C
0.03294d
0.05496
0.00878C
B"-^ ••^—••.,
kg/Mg
2.49246
0.9882
0.00004
0.03294
21.96
23.79365
0.04392
0.01647
0.02745
0.00439
=====
aAII emission factors are reported as found in the SPECIATE data base without rounding off
t frTn^tLr th SSI"°n ^f^ ''" SPECIATE data base are ^ported in Ib/ton of process activity.
It appears that the emisston factors reported above are uncontrolled factors.
Ib/ton (kg/Mg) of concentrated ore.
clb/ton (kg/Mg) of raw material processed.
dlb/ton (kg/Mg) of sinter processed.
elb/ton (kg/Mg) of zinc produced.
*Not currently used in the United States.
7-26
-------
Copper alloys are combinations of copper with other materials,
notably, tin, zinc, and lead. Also, for special applications,
combinations include such metals as cobalt, manganese, iron,
nickel, cadmium, and beryllium, and nonmetals, such as arsenic
and silicon.90
A list of- secondary copper smelters currently operating
within the United States is given in Table 7-io.92 A description
of the process used to manufacture- secondary copper and a
discussion' of the emissions resulting from the various operations
are presented below.
TABLE 7-10. DOMESTIC SECONDARY COPPER PRODUCERS
Smelter
1992 Capacity, Mg (tons)
Cerro Copper Products, Sauget, IL
70,000 (77,000)
Chemetco (Concorde Metals), Alton, IL
135,000 (148,500)
Franklin Smelting & Refining, Philadelphia, PA
16,000 (17,600)
Gaston Recycling Industries, Gaston, SC
110,000 (121,000)
Southwire Co., Carrolton, GA
105,000 (115,500)
Cyprus Casa Grande Corp., Lakeshore, A2
45,000 (49,500)
Source: Reference 92.
90
7.4.1 Process Description
The principal processes involved in copper recovery are •
scrap metal pretreatment and smelting. Pretreatment includes
cleaning and concentration to prepare the material for the
smelting furnace. Smelting involves heating and treating the
scrap to achieve separation and purification of specific metals.
The feed material used in the recovery process can be any
metallic scrap containing a useful amount of copper, bronze
7-27
-------
(copper and tin), or 'brass (copper and zinc). Traditional forms
are punchings; turnings and borings; defective or surplus goods;
metallurgical residues such as slags, skimmings, and drosses; and
obsolete, worn-out, or damaged articles, including automobile
radiators, pipe, wire, bushings, and bearings.
The type and quality of the feed material determines the
processes the smelter will" use. Due to the large variety of
possible feed materials available, the method of operation varies
greatly between plants. Generally, a secondary copper facility
deals with less pure raw materials and produces a more refined
product, whereas brass and bronze alloy processors take cleaner
scrap and do less purification and refining. Figure 7-4 is a
flowsheet depicting the major processes that can be expected in a
secondary copper-smelting operation. A brass and bronze alloying
operation is shown in Figure' 7-5.
Pretreatment of. the feed material can be accomplished
using several different procedures, either separately or in
combination. Feed scrap is concentrated by manual and mechanical
methods, such as sorting, stripping, shredding, and magnetic
separation. Feed scrap is sometimes briquetted in a hydraulic
press. Pyrometallurgical pretreatment may include sweating,
burning of insulation (especially from wire scrap), and drying
(burning off oil and volatiles) in rotary kilns.
Hydrometallurgical methods include flotation and leaching, with
chemical recovery.
In smelting, low-grade scrap is melted in a cupola
furnace, producing "black copper" (70 to 80 percent Cu) and slag;
these are often separated in a reverberatory furnace. From here,
the melt is transferred to a converter or electric, furnace 'to
produce "blister" copper, which is 90 to 99 percent Cu. The
actual temperature at which the smelting taikes place is not
-------
ENTERING THE SYSTEM
LEAVING THE SYSTEM
LOW-GRADE SCRAP
(SLAGS, SKIMMINGS, ^
BORINGS)
(•UfcL ^
PYROMETALLURGICAL
PRETREATMENT
(DRYING)
AIR |
' TREATED
' SCRAP "
GASES. DUST. METAL
OXIDES TO CONTROL
EQUIPMENT
FLUX
FUEL
AIR
CUPOLA
BLACK
COPPER
CARBON MONOXIDE.
PARTICULATE DUST. METAL
OXIDES. TO AFTERBURNER
AND PARTICULATE CONTROL
SLAG TO DISPOSAL
SLAG
FLUX
FUEL
AIR
SMELTING FURNACE
(REVERBERATORY)
SEPARATED
COPPER
FLUX
FUEL
AIR
i.
SLAG
GASES AND METAL
OXIDES TO CONTROL
EQUIPMENT
CONVERTER
BUSTER
COPPER
.
BLISTER
COPPER
CASTINGS AND SHOT
PRODUCTION
SLAG
AID
n in in -
(POLING)
FIRE REFINING
GASES AND METAL
OXIDES TO CONTROL
EQUIPMENT
FUGITIVE METAL
OXIDES FROM
POURING TO EITHER
HOODING OR PLANT
ENVIRONMENT
GASES, METAL DUST, TO
CONTROL DEVICE
! Oinoto* potential
cadmium emission source
REFINED
COPPER
Rgure 7-4. Process flow diagram for second-grade copper recovery.*^
'"'"" 7-29 "~ "
-------
HIGH-GRADE SCRAP
(WIRE, PIPE, BEARINGS,
PUNCHINGS, RADIATORS)
MANUALAND
MECHANICAL
PRETREATMENT
(SORTING)
FUGITIVE DUST
DESIRED
COPPER SCRAP
FUEL-
AIR .
DESIRED BRONZE
AND BRONZE SCRAP
FUEL
AIR
UNDESIRED
-» SCRAP TO
SALE
SWEATING
WIRE BURNER
PM.HC, ALDEHYDES
A CHLORIDES. FLUORIDES
T TO AFTERBURNER AND
—I PM CONTROL DEVICE
, GASES, AND
^METAL OXIDES TO
I CONTROL EQPT.
LEAD, SOLDER, BABBITT
METAL
BRASS AND BRONZE
FLUX.
FUEL-
ALLOY MATERIAL.
(ZINC. TIN. ETC.)
COPPER
I
MELTING AND
ALLOYING FURNACE
ALLOY
MATERIAL
I METAL OXIDES TO
CONTROL EQPT.
i
SLAG TO
DISPOSAL
FUGITIVE
METAL OXIDES
CASTING
• Denotes potential
cadmium emission source
Rgura 7-5. Process flow diagram for high-grade brass and bronze alloying.90
_ . i
7 - 3 0 ~~~ ~~
-------
known. However, it is believed that the operating temperatures
are not significantly different from that of primary copper-
smelting operations. The temperature in the cupola furnace is
believed to exceed the boiling point of cadmium, which is
approximately 767'°C (1413°F) . Therefore, most of the cadmium
potentially will be emitted from the cupola furnace.
Blister copper may be poured to produce shot or castings,
but is often further refined electrolytically or by fire
refining. The fire-refining process is essentially the same as
that described for the primary copper-smelting industry. The
sequence of events in fire refining is: (l) charging,
(2) melting in an oxidizing atmosphere, (3) skimming the slag,
(4) blowing with air or oxygen, (5) adding fluxes, (6) "poling"
or otherwise providing a reducing atmosphere, (7) reskimming, and
(8) pouring.
' To produce bronze or brass, rather than.copper, an
alloying operation is required. Clean, selected bronze and brass
scrap is charged to a melting furnace with alloys to bring the
resulting mixture to the desired final composition. Fluxes are
added to remove impurities and to protect the melt against
oxidation by air. Air or oxygen may be blown through the melt to
adjust the composition by oxidizing .excess zinc.
With zinc-rich feed, such as brass, the zinc oxide
concentration in the exhaust gas is sometimes high enough to make
recovery for its metal value desirable. This process is
accomplished by vaporizing the zinc from the melt at high
temperatures and then capturing the oxide downstream in a process
fabric filter.
The final step, is always casting of the suitably alloyed
or refined metal into a desired form, i.e, shot, wirebar, anodes,
7-31
-------
cathodes, ingots, or other cast shapes. The metal from the.melt
is usually poured into a ladle, or a small pot (which serves as a
surge hopper and a flow regulator) then continues into a mold,
7-4.2 Emission Control Measures90
* ,1 I '!
The principal pollutants emitted from secondary copper-
smelting activities are particulate matter in various forms.
Removal of insulation from wire by burning causes particulate
emissions of metal oxides and unburned insulation. The drying of
chips and borings to remove excess oils and cutting fluids can
result in large amounts of dense smoke, consisting of soot and
unburned hydrocarbons, being discharged. Particulate emissions
from the top of a cupola furnace consist of metal oxide fumes,
dirt, and dust from limestone and coke.
The smelting process utilizes large volumes of air to
oxidize sulfides, zinc, and other undesirable constituents of the
feed. This procedure generates considerable particulate matter
in the exit gas stream. The wide variation among, furnace types,
charge types, quality, extent of pretreatment, and size of the
charge is reflected in a broad spectrum of particle sizes and
variable grain loadings in the escaping gases. One major factor
contributing to differences in emission rates is the amount of
zinc present in scrap feed materials; the low-boiling zinc
evaporates and combines with air oxygen, producing zinc oxide
fumes.
Metal oxide fumes from furnaces used in secondary smelters
have been controlled by fabric filters, ESP's, or wet scrubbers.
Control efficiency by fabric filters may be better than
99 percent, but cooling systems are needed to prevent the hot
exhaust gases from damaging or destroying the bag-filters. A
two-stage system using both water jacketing and radiant cooling
7-32 •' " , ."'
-------
is common. Electrostatic precipita'tors are not as well suited to
this application, having a low-collection efficiency for dense
particulates, such as oxides of" lead and zinc. Wet scrubber
installations also are relatively, ineffective in.the secondary
copper industry. Scrubbers are useful, mainly for-particles
larger than 1 micron, but the metal oxide fumes''generated are
; generally^submicron in.size.
Particulate emissions associated with drying kilns can be
similarly controlled. Drying temperatures up to 1SO°C (302°F)
produce relatively cool exhaust gases, requiring no precooling
for control by fabric filters.
Wire burning generates large amounts of'particulate
•
matter, largely unburned combustibles. These emissions can be
effectively controlled by direct-flame afterburners, with an
efficiency of 90 percent or better if the afterburner combustion
temperature is maintained above 1000°C (1832°F). If the
insulation contains chlorinated organics, such as polyvinyl
chloride, hydrogen chloride gas will be generated and will not be
controlled by the afterburner.
One source of fugitive emissions in secondary smelter
operations is charging of scrap into furnaces containing molten
metals. This often occurs when the scrap being processed is not
sufficiently compacted to allow a full charge to fit into the
furnace prior to heating. The introduction of additional
material onto the liquid metal surface produces significant
amounts of volatile and combustible materials and smoke, which
can escape through the charging door. Briquetting the charge
offers a way to avoid fractional charges. When fractional
charging cannot be eliminated, fugitive emissions are reduced by
turning off the furnace burners during charging. This reduces, -
7-33
-------
the flow of exhaust gases and enhances the ability of the exhaust
control system to handle the emissions.
Metal oxide fumes are generated not only during melting,
but also during pouring of the molten metal intq the molds.
Other dusts may be generated by the charcoal, or- other lining,
u*sed in association with the mold. Covering the metal surface
with ground charcoal is a method used to make ."smooth-top"
ingots. This process creates a shower or sparks, releasing
emissions into the plant near the furnace top and the molds being
filled.
7.4.3 Emissions
Cadmium may.be expected to be present in the scrap metals
that are processed to recover secondary copper. Therefore,
cadmium emissions can be expected from secondary copper-smelt ing
operations. Table 7-11 presents estimates of cadmium emissions
reported by four ^facilities during 1989 and 1990 as required
under SARA Title III regulations.7'97 However, no test data are
available pertaining to cadmium emissions from secondary copper-
smelting operations. The only available emission factor data are
from the SPECIATE data base. These data show the cadmium
emission factor for electric- induction furnace at secondary
copper-smelting facilities to be 1.2 g/Mg (0.0024 Ib/ton) of
material charged into the furnace.91 Because the validity of
these emission factors cannot be verified, extreme caution should
be exercised'when using them.
7.5 SECONDARY ZINC RECOVERY FROM METALLIC SCRAP
The secondary zinc industry processes obsolete and scrap
materials to recover zinc as slabs, dust> and zinc oxide.90
Table 7-12 presents alistof U.S. facilitief where zinc
7-34
-------
TABLE 7-11. SECONDARY COPPER PRODUCERS REPORTING CADMIUM
EMISSIONS IN THE 1989 AND 1990 TOXICS RELEASE INVENTORY
Carrolton, GA
57 (125)a
=ranklin Smelting & Refining
Philadelphia, PA
454
Gaston Copper Recycling
Industries
Gaston, SC
Chemetco
Alton, IL
Source: References 7 and 97.
aThe emission rate reported is for 1989.
°The emission rate reported is for 1990.
4.5 (10)1
680 (1,496)b
currently is recovered from metal scrap. Cadmium can be expected
to be present in the metallic scrap that is processed to recover
zinc, and therefore be emitted as an air pollutant during
different processing steps. A description of the process used to
manufacture zinc from metallic scrap is presented below.
7 -5-1
Process Descript-r -1,
Processing involves three operations: scrap pretreatment,
melting, and refining. Processes typically used in each
operation are shown in Figure 7-6.. Molten product zinc may be
used in zinc galvanizing-.
Scrap Pretreatment --
Pretreatment is the partial removal of metal and other
contaminants from scrap containing zinc. Sweating separates zinc
from high-melting metals and contaminants by melting the zinc in
kettle, rotary, reverberatory, muffle or electric resistance
furnaces. Usually, the product zinc then is directly used in
melting, refining or alloying processes. The high-melting
residue is periodically raked from the furnace- and further
processed to recover zinc. These residues may be processed by
7-35
-------
TABLE 7-12. DOMESTIC PRODUCERS OF SECONDARY ZINC
FROM METALLIC SCRAP
Smelter
Arco Alloys, Inc.
W.J. Bullock, Inc.
T.L. Diamond & Co., Inc.
Florida Steel Co.
Gulf Reduction Corp.
Hugo Neu-Proler Co.
Huron Valley Steel Corp.
Indiana Steel & Wire Co., Inc.
Interamerican Zinc Inc.
New England Smelting
Works, Inc.
Nueor Yamato Steel Co.
The River Smelting & RFG
Co.
Zinc Corp. of America
Zinc Corp. of America
Location
Detroit, Ml
Fairfield, AL
Spelter, WV
Jackson, TN
Houston, TX
Terminal Island, CA
Belleville, Ml
Muncie, IN
Adrian, Ml
West Springfield, MA
Blytheville, AR
Cleveland, OH
Palmerton, PA
Bartlesville, OK
1990 Production capacity,
Mg (tons)
See footnote a
See footnote a
See footnote a
See footnote a
See footnote a
See footnote a
See footnote a
See footnote a
See footnote a
See footnote a
Unknown
Source: Reference 95.
aThe total zinc production capacity for all 13 plants is 58,000 Mg (63,800 tons).
Individual capacity data are not available.
crushing/screening to recover impure zinc or by sodium carbonate
leaching to produce zinc oxide. The temperature at which the
pretreatment takes place may be highly variable, depending on the
type of scrap, it is believed that the temperature at which the
pretreatment takes place may be comparable to that of primary
zinc operations. Therefore, the pretreatment step may result in
cadmium emissions.
7-36
-------
I
g
_j
UJ
cr
UJ
tr
a.
CO
^C
'35
to
0)
u
o
o
to
•a
o
o
'
2
CD
CO
o
0)
U
o
CO
CO
ul
7-37
-------
In crushing/screening, zinc-bearing residues are
pulverized or crushed to break the physical bonds between
metallic zinc and contaminants. The impure zinc is then
separated .in a.screening or pneumatic classification step.
In sodium carbonate leaching, the zinc-bearing residues
are converted to zinc oxide, which can be reduced to zinc metal.
They are crushed and washed to leach out zinc from contaminants.
The aqueous stream is then treated with sodium carbonate,
precipitating zinc as the hydroxide or carbonate. The
precipitate is then dried and calcined to convert zinc hydroxide
into.crude zinc oxide. The ZnO product is usually refined to
zinc at primary zinc smelters.
Melting--
Zinc is melted at 425-590°C (797-l094°F) in kettle,
crucible, reverberatory, and electric induction furnaces. Zinc
to be melted may be in the form of ingots, reject castings,
flashing or scrap. Ingots, rejects, and heavy scrap are
generally melted first to provide a molten bath to which light
scrap and flashing are added. Before pouring, a flux is added
and the batch agitated to separate the dross that accumulates
during the melting operation. The flux floats the dross and
conditions it so it can be skimmed from the surface. After
skimming, the melt can be poured into molds or ladles. Any
residual cadmium left over from the pretreatment step may not be
emitted during the melting stage because the melting takes place
at a much lower temperature than the boiling point of cadmium.
'Refining/Alloying--
Additional processing steps may involve alloying,
distillation, distillation and oxidation, or reduction. Alloying
produces mainly zinc alloys from pretreated scrap. Often the
alloying operation is combined with sweating or melting.
7-38 " ~~* *:'"
-------
Distillation retorts and furnaces are used to reclaim zinc
from alloys or to refine crude zinc. Retort distillation is the
vaporization at 980-1250°C (1796-2232°F) of elemental zinc with
its subsequent.condensation as zinc dust or liquid zinc. Rapid
cooling of the vapor stream below the zinc melting point produces
zinc dust, which can be removed- from the condenser and packaged.
If slab zinc.is the desired product, the vapors are condensed
slowly at a higher temperature. The resultant melt .is cast into'
ingots or slabs. Muffle distillation furnaces produce .
principally zinc ingots, and graphite rod resistance distillation
produces zinc dust. Because the distillation takes place at
temperatures higher than the boiling point of cadmium (767°C
[1413°F]), cadmium may potentially be emitted during the
distillation step.
Retort and muffle furnace distillation and oxidation
processes produce zinc oxide dust. These processes are similar
to distillation through the vaporization step. In contrast, for
distillation/oxidation, the condenser is omitted, and the zinc
vapor'is discharged directly into an air stream leading to a
refractory-lined combustion chamber. Excess air is added to
complete oxidation and to cool the product. The zinc oxide
product is usually collected in a fabric filter.
In retort reduction, zinc metal is produced by the
reaction of carbon monoxide and zinc oxide to yield zinc and
carbon dioxide. Carbon monoxide is supplied by the partial
oxidation of-the coke. The zinc is recovered by condensation.
Zinc Galvanizing--
Zinc galvanizing is the coating of clean oxide free iron
or steel'with a thin layer of zinc by immersion in molten zinc.
The. galvanizing occurs in a vat or in dip- tanks- containing molten
zinc and cover flux.
-------
7.5.2 Emission Control Measures90
i
11 , | :
Emissions from seating and melting operations consist
principally of .particulates, zinc fumes, other volatile metals,
flux fumes, and smoke generated by the incomplete combustion of
grease, rubber and plastics in the zinc-bearing-'feed material.
Zinc fumes are negligible at low furnace temperatures, for they
have a low vapor pressure even at 480°C (89^°F). with elevated
temperatures, however, heavy fuming can result. Flux emissions
are minimized by the use of a nonfuming flux. Substantial
emissions may arise from incomplete combustion of carbonaceous
material in the zinc scrap. These contaminants are usually
controlled by afterburners. Further emissions are the products
of combustion of the furnace fuel. Since the furnace fuel is
usually natural gas, these emissions are minor. In reverberatory
furnaces, the products of fuel combustion are emitted with the
other emissions. Other furnaces emit the fuel combustion
products as a separate emission stream.
i •
Particulates from sweating and melting are mainly hydratecl
zinc chloride (ZnCl2) and ZnO, with small amounts of carbonaceous
material. These particulates also contain Cu, Cd, maganese (Mn) ,
and chromium (Cr). .
Fabric filters are most commonly used to recover
particulate emissions from sweating and melting. In one
application on a muffle-sweating furnace, a cyclone and fabric
filter achieved particulate recovery efficiencies in excess of
99.7 percent. In another application on a reverberatory sweating
furnace, a fabric filter removed 96.3 percent of the
particulates, reducing the dust loading from 0..513 g/Nm3 to
0.02 g/Nm3. Fabric filters show similar efficiencies in removing
particulates from exhaust gases of melting furnaces. • -
7-40
-------
Crushing and"screening operations also are sources of dust
.emissions. These particulates are .composed of Zn, Al, Cu, Fe,
lead (Pb), Cd, tin (Sn), and Cr, and they can be recovered from
hooded exhausts by fabric filters.
The sodium carbonate leaching process produces particulate
emissions of ZnO dust during the calcining,operation. This dust
can be recovered in fabric filters, although ZnCl2 in the dust
may cause plugging problems.
Emissions from refining operations are mainly metallic
fumes. These fume and dust particles are quite small, with sizes
ranging .from 0.05-1 M. Distillation/oxidation operations emit
their entire ZnO product in the exhaust gas. The ZnO has a very
small particle size (0.03'to 0.5 ft) and is recovered in fabric
filters with typical collection efficiencies of 98 to 99 percent."
Some emissions of zinc oxide occur during galvanizing, but
these emissions are small because of the bath flux cover and the
relatively low temperature maintained in the bath.
7.5.3 Emissions
Cadmium may be expected to be present in the scrap metals
that are processed to recover zinc. Therefore, cadmium emissions
can be expected from secondary zinc recovery operations. One
secondary smelter reported a cadmium emission rate of 588' ib/yr
during the year 1989.97 However, no test data are available
pertaining to cadmium emissions from secondary zinc recovery
operations. The only available emission factor data are from the
SPECIATE data base. Table 7-13 presents cadmium emission factors
for various emission points at secondary zinc-smelting facilities
as reported in the SPECIATE data base,91 Because the validity of
7-41"
-------
TABLE 7-13.
CADMIUM EMISSIONS FROM SECONDARY ZINC RECOVERY
FROM METAL SCRAP
Emission source
Retort furnace
Horizontal muffle furnace
Pot furnace
Galvanizing kettle
Calcining kiln
Rotary-sweat furnace
Muffle-sweat furnace
Electric resistance sweat furnace
Crushing/screening of zinc residues
Kettie-sweat furnace (general metallic scrap)
Reverberatory sweat furnace (general metallic scrap)
Cettie-sweat furnace (general metallic scrap)
teverfaeratory sweat furnace (general metallic scrap)
Retort and muffle distillation: Pouring
Retort and muffle distillation: Casting
Retort distillation/oxidation
Muffle distillation/oxidation
Notary sweating
Muffle sweating
Cettie (pot) sweating
Electric resistance sweating
letort and muffle distillation
Casting
Source
classification
code (SCO
30400801
30400802
30400803
30400805
30400806
30400809
30400810
3040081 1
30400812
30400824
30400828
30400834
30400838
30400851
30400852
30400854
30400855
30400862
30400863
30400864
30400865
30400872
30400873
Cadmium
emission factor3
Ib/ton
0.036,1 9b
0.03465b
0.00008b
0.00385*
0.06S53b
0.01 386b
0.01 648b
0.0077b
0.00327d
0.00847b
0.01 001 b
0.01 925b
0.02464b
0.00046b
0.00023b
0.0231 e
0.02318
0.000695
0.00082b
0.00043C
0.00039f
0.001 82b
0.00001 b
kg/Mg
0.018095
0.017325
0.00004
0.001925
0.034265
0.00693
0.00824
0.00385
0.001 635
0.004235
0.005005
0.009625
0.01232
0.00023
0.000115
0.01155
0.01155
0.000345
0.00041
0.000215
0.000195
0.00091
Source: Reference 91.
aAH emission factors are reported as found in the SPECIATE data base without rounding off
(Reference 91). Emission factors in SPECIATE data base are reported in Ib/ton of process activity. It
appears that the emission factors reported above are uncontrolled factors.
on (kg/Mg) of zinc produced.
^b/ton (kg/Mg) of zinc used.
dlb/ton (kg/Mg) of residue.
elb/ton (kg/Mg) of zinc oxide produced.
flb/ton (kg/Mg) of scrap processed.
T~-42
-------
these emission factors cannot be verified, extreme caution should
be exercised when using them.
7.6, SECONDARY .ZINC RECOVERY FROM STEEL PRODUCTION .
Zinc also is recovered from electric-arc -furnace (EAP) '
dust generated at iron and steel manufacturing facilities. A
study carried out in May 1985 by the Center for Metals Production
estimated that, approximately 14.5 percent of EAF dust is
processed for zinc recovery. One data source has reported that
cadmium content in the EAF dust is approximately 0.05 percent.
Thus, cadmium can potentially be emitted during the process of
recovering zinc from EAF dust.98
Table 7-14 contains a list of facilities in the U.S. that
are capable of processing. EAF dust.95 Of these facilities, only"
two actually recover zinc.99 A description of the processes used
to recover zinc from EAF dust is presented below.
7.6.1 Process Deacripi-1,0*98 ,100
The process of recovering zinc from EAF dust is carried
out in two steps. In the first step, nonferrous ingredients are
volatilized from the EAF dust. The second step consists of
processing the volatilized nonferrous ingredients in a rotary
furnace (calcining kiln) to produce a zinc oxide calcine.
Two processes are available to carry out the first step of
volatilizing nonferrous components from EAF dust. These are the
Waelz kiln and flame reactor processes.
Waelz kiln process-- . - .
Figure 7-7 presents a typical process flow diagram for the
Waelz kiln process, stn this process, EAF dust is fed along with
7-43""' ' '~~ ~" ~~ """ " " " "'
-------
TABLE 7-14. DOMESTIC PRODUCERS OF SECONDARY ZINC FROM EAF DUST
Company
Florida Steel Co.
Horsehead
Development
Resource Co., Inc.
Horsehead
Development
Resource Co., Inc.
Horsehead
Development
Resource Co., Inc.
Horsehead
Development
Resource Co., Inc.
Laclede Steel Co.
North Star Steel Corp.
Nucor-Yamamoto
Steel Co.
Zia Technology of
Texas Inc.
Location
Jackson, TN
Calumet City, IL
Monaca, PA
Palmerton, PA
Rockwood, TN
St. Louis, MO
Beaumont, TX
Blytheville, AR
Caldwell, TX
EAF processing
capacity, Mg (tons)
7,200 (7,920)
72,000 (79,200f
18,000i (19,800)
245,000 .(269,500)
90,000 (99,000)
36,000 (39,600)
27,000 (29,700)
11,000(12,100)
27,OQO (29,700)
Zinc recovering
capacity, Mg
(tons)3
1,400 (1,540)
75,000 (82,-500)b
See footnote b
See footnote b
See footnote b
6,000 (6,600)
5,000 (5,500)
1,800 (1,980)
4,500 (4,950)
Source: Reference 95.
aEven though there are nine facilities, which have the capability to process EAF, only two facilities,
Florida Steel and Nucor-Yamamoto Steel Co., actually recover zinc from EAF dust.9'9
The combined zinc capacity for all four locations of Horsehead Development Co., is 75,000 Mg
(82,500 tons). Data pertaining to individual capacities are not available.
7-44
-------
EAF DUST
|PM
COAL
WAELZ KILN
SILICA FLUX
ZnO
FUME
DUST
COLLECTOR
IRON RICH SLAG
t
PM
DUST
COLLECTOR
ZnO
CALCINE
KILN
t Denotes potential
cadmium emission source
ZINC CALCINE
figure 7-7. Process flow diagram for Waeiz kiln process.98
7-45
-------
anthracite coal and silica fluxes' into a rotary kiln. The kiln
contains two reaction zones: the solid material charge zone and
the gaseous zone above the solid zone. Coal in the solid zone
combusts to form carbon monoxide (CO) which reduces the metal
oxides, thus volatilizing the metals. Nonferrous metals
1 !
volatilize when the temperature in the kiln- reaches 1000 °C
(1832 °F) . When the nonferrous metals reach the gaseous zone upon
volatilization, they are again oxidized to form corresponding
metal oxides. The above processes are described by the following
chemical reactions that take place in the kiln:
Combustion reactions
C + CO
Reduction reactions
Fe3°4
ZnO + CO
CdO -f- CO
Oxidation reactiong
CO +
Zn +
Cd +
> CO
> 2CO
C0
C0
>> zn +
> cd +
> C02
> ZnO
> CdO
C0
C0
ZnO Calcine Formation--
The nonferrous metal oxide product formed by ZnO calcine
formation is captured in a fabric filter and subsequently
processed in a natural gas-fired calcining kiln to form zinc
calcine. Figure 7-7 also presents a typical process flow diagram
for the calcining kiln operation. In the calcining kiln, the
nonferrous metal oxides are introduced without any,additives, and
selective volatilization is carried out to separate cadmium,
-------
lead, chlorine, and fluorine. The volatilized material is
collected in a fabric filter. Zinc originally present in the
form of ZnO is recovered unaltered as residue from the calcining
kiln. The ZnO.can subsequently be. processed by electrathermic
process to recover zinc.
Flame Reactor Process-r
Figure 7-8 presents a flow diagram for the flame reactor
process used to volatilize nonferrous metals from dust. This
process is an alternative method for the Waelz kiln process. In
the flame reactor process, EAF dust is fed into a water-cooled,
natural gas-fired reactor. The combustion air is enriched with
oxygen raising the oxygen content to a level between 40 and
80 percent. Flame temperatures up to 2200°C (3992°F) can be
obtained this'way. As the EAF dust is introduced into the hot
.gases and temperatures reach 1600°C (2912°F), refractory
compounds present in the dust fuse to form molten slag. The
molten slag and the combustion gases are conveyed into a slag
convertor where iron-rich slag is continuously tapped. The
offgases exiting the separator are oxidized further to -form
metallic (nonferrous) oxides, which are recovered in a fabric
filter and shipped as feedstock to zinc-smelting facilities.
7.6.2 Emission Control Measure98 • 3.QO
Emissions resulting from processing of EAF dust chiefly
consist of particulate matter made up of nonferrous metallic
oxides (including cadmium oxide), which are - recovered in a fabric
filter. The fabric filter is used more as a product recovery
device than a control device.
7-47
-------
COMBUSTION
AIR COMPRESSOR
SLAG COOLING
TO MARKET -4
• DENOTES POTENTIAL CADMIUM EMISSION SOURCE
figure 7-8. Process flow diagram for zinc calcine formation.98
7-48
-------
7.6.3 Emissions100
Data pertaining to cadmium emissions from EAF dust
processing are.limited. One source has reported a cadmium
emission rate of 5.04 x 10'4 Ib/hr measured at the outlet of a
fabric filter servicing a flame reactor, which -corresponds to a
EAF dust processing rate of 40-lb./min (1.2 tons/hr) . -This
results in a cadmium emission factor of 2.1 x 10"4 kg/Mg
(4.2 x 10"4 Ib/ton) of EAF dust processed. No other details
pertaining to the test are available. Therefore, the validity of
this cadmium emission factor cannot be verified. The cadmium
emission factor must be used with extreme caution.
7-49
-------
-------
SECTION 8
EMISSIONS FROM MISCELLANEOUS-SOURCES
Cadmium is present in minerals, ores, and crudes extracted
from the earth and these materials are used in several
manufacturing processes. "These manufacturing processes can be
potential cadmium emission sources if they use cadmium containing
materials in thermal treatment steps. The manufacturing
processes described in this section are: iron and steel
production, portland cement manufacture, phosphate rock
processing, carbon black production, and mobile sources. This
section presents process information and emission control
measures, and estimates of cadmium emissions from each of these
sources.
8.1 IRON AND STEEL PRODUCTION101
Two types of iron and steel plants will be discussed in this
section: integrated and nonintegrated. Because cadmium can be
present as a trace contaminant in process feed materials such as
coal, iron ore, and scrap metal, process operations in both plant
types are potential cadmium emission sources.
Integrated iron and steel plants are those iron and
steelmaking facilities that are capable of starting with iron ore
as a raw material feed and producing finished steel products. At
a minimum, these facilities have blast furnace, facilities for pig
iron production;•steelmaking furnaces (generally one or more
basic oxygen furnaces), and steel finishing operations. Many
making operations, sinter plants, and
8-1
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electric arc furnace shops for melting scrap.: In its simplest .
form, the integrated iron and steel process begins with pig iron
production from iron ore or pellets in the blast furnace The ...
molten iron is.transferred from the blast furnace to the basic
oxygen furnace, where, the.hot pig iron and scrap metal are heated
and transformed metallurgically to carbon steel-: This carbon
steel is then cast and rolled into a final project. Table 8-1
provides a listing, of integrated iron and steel plant locations.
Nonintegrated plants consist of "minimills11 or specialty
mills that produce carbon'steel, stainless steel and other steel
alloys from scrap. Typical operations at these facilities
include electric arc furnaces for steelmaking and steel casting
and finishing operations, as well as alloying operations.
-Table C-l lists those facilities that use electric arc furnaces.
Total steel (carbon and alloy) production for 1991 was
79.7 x 10s Megagrams (Mg) (87.8 x 10s tons). Of this total,
70.7 x 10s Mg (77.9 x 10s tons) was carbon steel. In 1991,
nonintegrated plants produced 9.1 x 10s Mg (10:0 x 106 tons) of
stainless and alloy steel.101 in order to distribute this
production among furnace types, basic oxygen and open hearth
furnaces were assumed to produce only carbon steel. Using this
assumption estimated 1991 production levels for carbon steel were
47.8 x 10s Mg (52.7 x 10s tons) in basic oxygen furnaces, '
1.3 x 106 Mg (1.4 x 10 6 tons) in open hearth furnaces, and
16.7 x 10s Mg (18.4 x 10s tons) in electric arc furnaces. The
total stainless and alloy steel production of 9.1 x 106 Mg
(10.0 x 10s tons/yr) is assumed to be from electric arc furnaces.
Intermediates produced by integrated iron and steel plants in
1991 include 44.1 x 10s Mg (48.6'x 10s tons) of pig iron and
21.8 x 106" Mg (24.0 x 10s tons) of coke (including both furnace
and merchant coke plants but excluding coke breeze).
8-2
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TABLE 8-1. INTEGRATED IRON AND STEEL PLANTS
Company
Facility
City and State
No. of
basic
oxygen
furnaces
No. of
blast
furnaces
Acme Steel Company
Acme Steel Company
Allegheny Ludlum Corp.
Armco Steel Company, L.P."
Armco Steel Company, L.P."
Armco Steel Company, L.P.
Bethlehem Steel Corp.
Bethlehem Steel Corp.9
Bethlehem Steel Corp."
Geneva Steel Company"
Gulf States Steel"
nland Steel Company15
LTV Steel Flat Rolled & Bar Co.
LTV Steel Flat Rolled & Bar Co."
LTV Steel
dcLouth Steel
National Steel Corporation
National Steel Corporation
tauge Steel Company
Sharon Steel, Incorporated
Sharon Steel, Incorporated
J.S. Steel Corporation (USX)
U.S. Steel Corporation (USX)
U.S. Steel Corporation (USX)
U.S. Steel Corporation (USX)"
USS/Kobe Steel Company
Warren Consolidated Inc.
Weirton Steel Company"
Mieeling-Pittsburgh Steel Corp.
/Vheeling-Prttsburgh Steel
Corp.0
Chicago Plant
Riverdale Works
Brankenridge Works
Ashland Works
Hamilton Plant
Middletown Works
Bethlehem Plant
Bums Harbor Plant
Sparrows Pt. Plant
Geneva Works
Gadsen Works
Cleveland Works
ndiana Harbor Works
LTV Stills
Trenton Works
Granite City Steel
Great Lakes Steel
Rouge Works
:arreli Works
rionessen, Inc.
Edgar Thomson Plant
Fairfield Works
Fairless Works
Gary Works
/Varren Facility
A/eirton Works
iteubenville Plant, N
iteubenviile Rant, S
Chicago, IL
Riverdale, IL
Natrona, PA -
Ashland, KY
Hamilton, OH
Middletown, OH
Bethlehem, PA
Bums Harbor, IN
Sparrows Pt., MD
Orem, UT
Gadsen, AL
East Chicago, IN
Cleveland, OH
East Chicago, IN
Chicago, IL
Trenton, Ml
Granite City, IL
Ecorse, Ml
Dearborn, Ml
Farrell, PA
Sharon, PA
Braddock, PA
Fairfield, AL
Fairiess Hills, PA
Gary, IN
.orain, OH
/Varren, OH
/veirton, WV
iteubenville, OH
vlingo Junction, OH
OTAL
Source: Reference 102.
aAlso has a sinter plant at this location.
Has a sinter plant at the Indiana Harbor Works facility.
cHas a sinter plant at the Follansbee Rant, Follansbee, WV.
65
74
8-3
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8.1.1 Process Description
Figure 8-1 provides a flow diagram for iron and steel
production. The principal components of the process -are iron
production, steelmaking, and steel finishing. However/ two
important ancillary components are coke making and sinter
production. The process steps discussed below apply to an
integrated plant. Process -differences will be noted for
nonintegrated plants. . '
Frequently, the first step in the process for an integrated
plant is to produce metallurgical coke (elemental .carbon) for the
blast furnace. Coke is used to: (1) provide a substrate for raw
materials in the blast furnace, (2) function as fuel for the hot
blast air, and (3) remove iron ore oxides. Table 8-2 lists the
coke production capacities for batteries located at or associated
circle integrated plants. Nonintegrated plants do not use blast
furnaces and, therefore, do not need coke. The coke is made from
coal that is pulverized and then heated in a coke oven,without
oxygen at 1050°C (1925-P) for 12 to 20 hours. Volatiles are
driven off, and elemental carbon (coke) and ash are formed.
Because cadmium is a trace contaminant in coal, there is a
potential for emissions when the coal is heated.
Two types of ovens (arranged in batteries) can be used: a
slot oven and a nonrecovery oven. The slot oven process recovers
volatiles that are driven off during the heating process, and
these volatiles are refined to produce coke-oven gas, tar,
sulfur, ammonium sulfate and light oil. Because most of the
volatile materials generated by the oven are cycled through
recovery process with organic condensation steps, cadmium
emissions generated by by-product cokemaking facilities is
expected to be negligible. However, nonrecovery'dvena do riot '
8-4
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o
en
to
•a
15
5
o
o>
OJ
a
CO
3
CD
8-5
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TABLE 8-2. COKE PRODUCTION CAPACITY'FOR INTEGRATED IRON
IN THE UNITED STATES IN 1991
AND STEEL FACILITIES
Facility
Acme Steel, Chicago, IL
Armco, Inc., Ashland, KY
Arriico, Inc., Middleton, OH
Bethlehem Steel. Bethlehem, PA
Bethlehem' Steel, Bums Harbor, IN
Bethlehem Steel, Lackawanna, NY
Bethlehem Steel, Sparrows Point, MD
Geneva SteeJ, Orem, UT
Gulf States Steel, Gadsden, AL
Inland Steei, East Chicago, IN
LTV SteeJ, Pittsburgh, PA
LTV Steel, Chicago, IL
LTV SteeJ, Cleveland, OH
LTV Steel, Warren, OH
National Steel, Granite City, IL
National Steel, Ecorse, Ml
USS, Div, of USX Corp., Clairton, PA
USS, Div. of USX Corp., Gary, IN
Wheeling-Pittsburgh Steel, East Steubenville,
WV
Total
""""*" * ' * *-"• - — — —— — — —
No. of
batteries
2
2
3-
3
2
2
3.
1
2
6
5
1
2
1
2
1
12
6
4
60
Total No. of
ovens
100
146
203
284
164
152
210
208
130
446
315
60
126
85
90
78
816
422
224
4,259
Total capacity |
Megagrams
• per day
1,626
2,743
4,608
4,007
4,400
1,902
4,134
2,323
2,845
5,868
5,491
1,626
3,251
1,524
1,544
940
1 2,843
7,249
3,861
72,835
Tons per
:>day
•1 ,600 1
2,700 1
4,535
3,944 1
4,380 ||
1,872 ||
4,069 ||
2,250
2,800 ||
5,775 |
5,404
1,600
3,200 ||
1 ,500 ||
1 ,520 (I
925 ||
12,640
7,135 ||
3,800 I
71,649 |
Source: Reference 104.
8-6
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recover volatiles and instead combust them.
source of cadmium emissions.
These ovens may be a
After the.coking cycle is complete, the coke is quickly
cooled down by a quenching tower, to prevent product loss via
combustion. Further cooling occurs after the wa'ter is drained
from'the coke, it is sized to remove the undersized material
(coke breeze) and transferred to storage piles. Because cadmium
may remain as a trace contaminant" in the coke, small quantities
of cadmium may be released as fugitive emissions during these
handling, transfer, and storage operations.
A second ancillary process found at many, integrated plants
is the sintering operation. The sintering process is a
materials-recovery process, which converts fine-sized raw
materials, including iron ore, coke breeze, limestone, mill
scale, and flue dust, into an'agglomerated product called
"sinter."103 Cadmium can be contained in the iron ore used to
produce sinter and may be emitted when the sinter mixture is
combusted. The raw materials are placed on a continuous,
travelling grate called the sinter strand. A burner hood, at the
beginning of the sinter strand, ignites the coke in the mixture.
Combustion air is drawn down through the material bed and into a
common duct leading to a gas cleaning device. The fused sinter
is discharged from the sinter strand where it is crushed and
screened. Undersized sinter is recycled to the mixing mill and
back to the strand. The remaining sinter product is cooled in
the open air or in a circular cooler with water sprays or
mechanical fans.
The initial process common to all integrated plants is the
blast furnace, which is used to produce molten iron ("pig iron").
Iron ore, coke, limestone flux and sinter are introduced '
rcharged") into the top of the furnace. Heated air is injected
8-7
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through the bottom of. the furnace. This blast air combusts the
coke contained in the breeze to melt the sinter, and flux with
the iron oxides in the ore and form molten iron, slag, and carbon
monoxide (CO).. The molten iron and the slag collect in the
hearth at the base of the furnace and are periodically tapped.
The CO is collected through offtakes.at the.top-of the furnace
Because the iron ore contains traces of ca.dmium, emissions are
possible as particulate matter (PM)- entrained in the CO *
However, this CO will be used as fuel within the plant after it
is cleaned of PM; consequently, cadmium emissions are expected to
be negligible.
* ' „ • ! ! •!' • ' ! '
The molten iron from the blast furnace undergoes
desulfurization, after which it is introduced to a basic oxygen
furnace (EOF) or open hearth furnace to make steel. These
furnaces use oxygen as a refining agent, 'in a EOF, the raw
material is typically 70-percent molten metal and 30-percent
scrap metal. Again, cadmium may be present: as a contaminant in
the scrap metal. The oxygen reacts with carbon and other
impurities in the raw material and removes them from the molten
metal. Large quantities of carbon monoxide (CO) are produced by
the exothermic reactions in the BOF. These gases, which may
contain cadmium, frequently are burned at the mouth of the
furnace to oxidize CO. The gases are then vented to gas cleaning
devices before being discharged to the atmosphere.
There are two types of BOF's. Conventional BOF's blow
oxygen into the top of the furnace through a water-cooled lance
The newer Quelle Basic Oxygen process (Q-BOP) furnaces inject
oxygen through tuyeres, which are located in the bottom of the
furnace. Typical cycles involve scrap charge, hot metal charge
oxygen blow (refining) period, testing for temperature and
chemical composition of the steel, alloy additions and reblows - .
8-8
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(if 'necessary), tapping, and slagging. The full furnace cycle
typically ranges from 25 to 45 minutes.
The open-hearth furnace (OHF) is a shallow, refractory-lined
basin in which scrap and molten iron are melted together and then
refined into steel. The mixture of scrap and hot metal may
consist of either all scrap or all hot metal, but. a half-and-
half mixture of scrap and metal is common. Because scrap is
used, there is a potential for cadmium emissions; however, no
information was available to evaluate emissions potential.
Because these furnaces have limited use and are being eliminated,
they are not considered a significant cadmium emission sources.
Nonintegrated plants use electrical arc furnaces (EAF's) to
produce carbon and alloy steels. The raw material for an EAF is
typically 100 percent scrap, which is a source for cadmium
emissions. These furnaces are cylindrical and refractory-lined.
They have carbon electrodes that are raised or lowered through
the furnace roof. With electrodes raised, the furnace roof can
be moved aside to allow scrap steel to be introduced by an
overhead crane. Alloying agents and fluxing materials are
usually added through the doors on the side of the furnace. Heat
generated by the electrical current passing between the
electrodes is used to melt the scrap. After melting and refining
periods, the slag and steel are poured from the furnace by
tilting. The production of steel in an EAF is a batch process.
Cycles, or "heats," range from about 11/2 to 5 hours for carbon
steel production and from 5 to 10 hours, or more, for alloy steel
production. Because cadmium may be contained in the scrap metal
used to feed EAF's, they are considered to be a potential source
of cadmium emissions.
After production in-either a BOF, OHF, or-SAP,- the molten
steel is cast into molds or is continuously cast to form a
8-9
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finished product. This final" product consists of 'shapes called
blooms, slabs, and billets. No cadmium emissions are expected
from this final process step from the cold steel, because cadmium
is not expected to be present in the molten steel product.
8-1-2 Emission Control Measures102
Cadmium is usually emitted as fine particulate matter from
high temperature operations such as the furnaces found in the
iron and steel plants. Cadmium emissions from iron and steel
production are expected from furnaces, BOP's, OHF's, EAF's,
sintering operations, and possibly, charging of by-product ovens
and nonrecovery coke oven operations. No specific data were
available on cadmium control from iron and steel operations.
However, because these processes generate primarily fine
particles, the cadmium control efficiencies are assumed to be
equivalent to the overall PM control efficiencies for
electrostatic precipitators, high energy scrubbers, and fabric
filters applied to high temperature processes.
Information available on one nonrecovery oven shows that
charging emissions are controlled with a travelling hood that
vents to a baghouse.105 Total capture efficiency was estimated
at 70 percent, and.cadmium was not detected in the baghouse
samples. The detection level was 0.5 milligram per kilogram
(mg/kg) [parts per million (ppm)'].105 Therefore, it can be
assumed there are no significant cadmium emissions from
nonrecovery coke ovens.
Estimates on control device efficiency for PM are available '"'
for ESP's, scrubbers, and baghouses used in sintering operations.
These efficiencies range from 93 percent (for a cyclone, ESP,
scrubber configuration) to 99.9 percent (for a baghouse) and are
based on State permitting information.
8-10
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Controls used for blast furnaces include cyclones or gravity
collectors in combination with scrubbers, baghouses, and ESP's.
Efficiencies for baghouses ranged from 98 to 99.25 percent. If
followed by a scrubber, they could be as. high as 99.9 percent.
Gravity collectors used with scrubbers could achieve 99 to
99.9 percent efficiency. Scrubbers used with an ESP have removal
efficiencies of 99.3 to 9-9.9 percent.
Control devices used for BOF's include scrubbers, fabric
filters and ESP's. Control efficiency estimates are: (l) 99.4
to 99.7 percent for ESP's, (2) 98.5 to 99.9 percent for
scrubbers, (3) 99 percent for baghouses, and (4) 96 percent for a
cyclone with scrubber. No information was available on control
devices used for open hearth furnaces.
Because a substantial portion of the emissions from, an EAF
are fugitive in nature, emission control systems include capture
and collection systems. The capture systems include a primary
system,, which is designed to capture emissions during the melt,
and a secondary system, which is designed to capture fugitive
emissions from charging, tapping, and furnace leakage.
Typically, primary collection systems are either direct shell
evacuation (DSE) systems (also called'fourth hole systems) or
side draft hood systems, and secondary emissions are collected
via canopy hoods, close-capture local hoods, or furnace
enclosures. Gases collected by these systems are generally
directed to a fabric filter for PM collection. Available
information indicates that properly designed and operated
secondary systems are expected to capture 75 to 95 percent of the
emissions from EAF's, while SSE systems collect 99 percent of the "
emissions generated during the melt. Performance data for fabric
filters are generally presented as achievable•outlet
concentration levels but well-operated units are expected to
^ achieve efficiencies that exceed 99 percent.
8-11
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8.1.3 Emissions101/106 - ' .
Table 8-3 summarizes- cadmium releases reported in the
1990 Toxic Chemical Release Inventory (TRI). Test data for
cadmium emissions are only available from-one plant,;Bethlehem
Steel at Sparrows Point, Maryland. Because- these data are not
complete and could not be validated, they should be used
cautiously, it should be noted that this particular plant '
reported no cadmium emissions.in the 1990 TRI. The test data for
this one facility are summarized in Table 8-4, but no information
is available on their representativeness.
No specific data for cadmium emissions from EAF's were found
in the literature, and no emission test dafa were available to
permit the calculation of cadmium emissions.
8.2 PORTLAND
MANUFACTURING9 0/107-109
More than 30 raw materials are used to manufacture portland
cement. These materials can be classified into four basic
classes of raw materials: calcarious, siliceous, argillaceous,
and ferriferous. Two processes, the wet and dry processes, can
be used to manufacture portland cement. In 1990, there were a
total of 212 U.S. cement kilns with a combined total clinker
capacity of 73.5 X 10s Mg (81.1 x 10s tons). Of this total,
11 Jcilns with a combined .capacity of 1.8 x 10s Mg (2.0 x 10s tons)
were inactive. The total number of active kilns was 201 with a
clinker capacity of 71.8 x 10* Mg (79.1 x 10* tons)'. The name,
location, and clinker capacity of each kiln is presented in
Appendix C. Based on 1990 U.S. cement kiln capacity data/ an
estimated 68 percent of the portland cement is manufactured using
the dry process, and the remaining 32 .percent based on the wet
process. A description of the processes used to manufacture
8-12
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TABLE 8-3. CADMIUM RELEASES REPORTED BY IRON AND STEEL FACILITIES IN 1990 TRI
Facility/location
ARMCO, Kansas City, MO
Barbary Coast Steel Corp., Kent, WA
Bethlehem Steel, Bethlehem, PA
Birmingham Bolt, Birmingham, AL
Birmingham Bolt, Bourbonnais, IL
Bloomfield Foundry Inc., Bloomfield, IA
BSC Steel, Jackson, MS
Cascade Steel Rolling Mills, McMinnville, OR
Citisteel USA, Clairmont, DE
Dana Corp., Richmond, IN
East Jordan Iron Works, East Jordan, Ml
GMC Saginaw Grey Iron Plant, Saginaw, Ml
John Deere Foundry, Waterloo, IA
Lukens Steel, Coatesville, PA
Newport Steel Corp., Newport, KY
Norfolk Steel Corp., Chesapeake, VA
Nucor Steel, Polymouth, UT
Salmon Bay Steel Corp., Kent, WA
Seattle Steel, Seattle, WA
Sheffield Steel Corp., Sand Springs, OK
Roanoke Electric Steel, Roanoke, VA
Rouge Steel, Dearborn, Ml
TOTAL
Source: Reference 7.
8-13
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TABLE 8-4. CADMIUM EMISSIONS REPORTED f ROM BETHLEHEM STEEL
SPARROWS POINT, MARYLAND
Operation source
— Transfer points controlled by scrubber
Limestone stockpile (fugitives)
Coke breeze unloading (fugitives)
Stock House (fugitives)
- Windbox and discharge controlled by baghouse
Blast furnace
— Uncontrolled casthouse roof monitor
— Taphole and trough (not runners)
Basic oxygen furnace (BOR
- Uncontrolled
— Fugitives
BOF charging
~ At source
~ Controlled by baghouse
- Hot metal transfer at source
tapping
i MI
Source: References 102 and 90.
aTypical of older furnaces with no controls, or for canopy hoods or total casthouse
evacuation.
-------
Portland cement and the emissions resulting from the various
operations is presented below.
8.2.1 Process _Description:' , i;. ... ..;. .
Figure 8-2 presents a basic flow diagram of the portland
• cement manufacturing process.. .The process can be divided into"
four major steps: raw material acquisition and handling, kiln
feed preparation, pyreprocessing, and finished cement grinding.
The initial step in the production of portland cement
manufacturing is raw materials acquisition. Calcium, which is
the element of highest concentration in portland cement, is
obtained from a variety of calcareous raw materials, including
limestone, chalk, marl, sea shells, aragonite, and an impure
limestone known as "natural cement rock.". The other raw
materials--silicon, aluminum, and iron—are obtained from ores
and minerals, such as sand, shale, clay, and iron ore. Cadmium
is expected to be present in the ores and minerals extracted from
the earth. The only potential source of cadmium emissions from
raw material acquisition would be due to wind blown cadmium-
containing particulate from the quarry operations. Cadmium
emissions are expected to be negligible from these initial steps
in portland cement production.
The second step involves preparation of the raw materials
for pyroprocessing. Raw material preparation includes a variety
of blending and sizing operations designed to provide a feed with
appropriate chemical and physical properties. The raw material
processing differs, somewhat for wet- and dry-process. At
facilities where the dry process is used, the moisture content in
the raw material, which can range from less than 1 percent to
greater than 50 percent, is reduced to less than 1 percent.
Cadmium emissions can occur during this drying_proces_sj3ut .are
8-15
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Cfl
w
LU
O
o
tr
a.
03
o
03
CO
0)
u
o
CD
U
0]
M—
03
*•<
-------
anticipated to be very low because the drying temperature is much
below the boiling point of cadmium: At some facilities,- heat for
drying is provided by the exhaust gases from the pyroprocessor.
At facilities where the .-wet-process is used, water is added to
the raw material during the grinding step, thereby producing a
pumpable slurry containing approximately 65' percent solids.
Pyroprocessing (thermal treatment) of the raw material is
carried out in the kiln, which is the heart of the portland
cement manufacturing process. During pyroprocessing, the raw
material is transformed into clinkers, which are gray, glass-
hard, spherically-shaped nodules that range from 0.32 to 5.1 cm
(0.125 to 2.0 in.) in diameter. The chemical reactions and
physical processes that take place during pyroprocessing include:
1. Evaporation of uncombined water from raw materials as
material temperature increases to 100°C (212°F),
2. Dehydration as the material temperature increases from
100«C to-approximately 430«C (800°F) to form the oxides of
silicon, aluminum, and iron,
3. Calcination, during which carbon dioxide (C02) is
evolved, between 900«C (1650°F) and 982«C (1800°F), to form
calcium oxide,
4. Reaction of the oxides in the burning zone of" the rotary
kiln to form cement clinker to form cement clinker at
temperatures about 1510°C (2750°F).
.The rotary kiln is a long, cylindrical, slightly inclined,
refractory-lined furnace. The raw material mix is introduced
into the kiln at the elevated end, and the .combustion fuels are
_intr°d^d_3nt°, thefcila at the lower end, in a
8-17
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counter-current manner. The rotary motion of the kiln'transports
the raw material from the elevated end to the lower end.. Fuel
such as coal, or natural gas, or occasionally oil, is used to
provide energy.for calcination. Cadmium is present, in coal and
oil. Tables 6-4 and 6-11 presented data pertaining to cadmium
content in coal and oil, respectively. Itee'-of other fuels, such
as chipped rubber, petroleum coke, and waste solvents, is
becoming increasingly popular. Combustion of fuel during the
pyroprocessing step contributes to potential cadmium emissions.
Cadmium may also be present in the waste-derived fuel mentioned
above. Because cadmium evaporates at approximately 767°C
(1,413°F) and cadmium compounds at higher temperatures, most of
the cadmium present in the raw materials can be expected to be
incorporated into the clinker. Cadmium that is volatilized in
the kiln is either removed in the bypass g-ases or the preheater/
Pyroprocessing can be carried out using one of five
different processes: wet process, semi-dry, dry process, dry
process with a preheater, and dry process with a
preheater/precalciner. These processes essentially accomplish
the same physical and chemical steps described above. The last
step in the pyroprocessing is the cooling of the clinker. This
process step recoups up to 30 percent of the heat input to the
kiln system, locks in desirable product qualities by freezing
mineralogy, and makes it possible to handle the cooled clinker
with conventional conveying equipment. Finally, after the cement
clinker is cooled, a sequence of blending and grinding operations
is carried out to transform the clinker into finished portland
cement.
8-2.2 Bnission Control Measure-^
With the exception of the pyroprocessing operations, the
emission sources in the portland cement industry can be
8-18
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classified as either process emissions or fugitive emissions.
The primary pollutants resulting from the fugitive sources are
PM. The control measures used for these fugitive dust sources
are comparable.to those used throughout the mineral products
industries.
Methods used to reduce particulate- levels in the ambient air
due to vehicular traffic include paving and road wetting.
Additional methods that are applied to other open dust sources '
include water sprays with and without surfactants, chemical dust
suppressants, wind screens, and process modifications to reduce
drop heights or enclose storage operations.
Process fugitive emission sources include materials handling
and transfer, raw milling operations in dry process facilities,
and finish milling operations. Typically, particulate emissions'
from these processes are captured by a ventilation system with a
fabric filters. Because the dust from these.units is returned to
the process, they are considered to be process units as well as
air pollution control devices. The industry uses shaker, reverse
air, and pulse jet filters, as well as some cartridge units, but
most newer facilities use pulse jet filters. For process
fugitive operations, the-different systems are reported to
achieve typical outlet PM loadings of 45 milligrams per cubic
meter mg/m3 (0.02 grains per actual cubic foot [gr/acf]).
Because the cadmium is in particle form, the performance of these
systems relative to cadmium control is expected to be equivalent
to this overall particulate performance. However, no data are
available on cadmium performance of fugitive control measures.
In the pyroprocessing units, PM emissions are controlled by
fabric-filters (reverse air, pulse jet, or pulse plenum) • and
ESP's. The reverse air fabric filters and ESP's typically used
to contro1 kil11. e*?151113^3 are reported to achieve outlet. PM
8-19
-------
loadings of 45 mg/m3 (0.02 gr/acf). Clinker.cooler systems are
controlled most frequently with pulse jet or pulse plenum fabric
filters. A few gravel bed (GB) filters'have been used on clinker
coolers. .
8-2.3 Emissions
The principal sources of cadmium emissions are expected to
be from the kiln. A large majority of the cadmium input from the
raw materials and fuels is incorporated into the clinker.
Cadmium volatilized from the kiln is either removed in the bypass
gases or the preheater. Negligible quantities of emissions would
be expected in the raw material processing and mixing steps
because the only source of cadmium would be fugitive dust
containing naturally occurring quantities of cadmium compounds in
the limestone. Processing steps that occur after the calcining
process in the kiln would be expected to be a much smaller source
of emissions than the kiln. Potential cadmium emission sources
are denoted by solid circles in Figure 8-2. Emissions resulting
from all processing steps' include partficulate matter.
Additionally, emissions from the pyroprocessing step include
other products of fuel combustion such as sulfur dioxide (SO2),
nitrogen oxides • (NOX) , carbon dioxide (C02), and carbon monoxide
(CO). Carbon dioxide from the calcination of limestone will also
be present in the flue gas.
Cement kiln test reports were reviewed for facilities
performing Certification of Compliance (COC) tests required of
all kilns burning waste derived fuel (WDF) . Nineteen of the test
reports contained sufficient process information to allow
calculation of cadmium emission factors for the kiln stack; these
data are shown in Appendix C, Table C-3. The results from these
19 tests showed a range in average emission factors'from
1.1 x ID'3 g/Mg of clinker (2.2 x 10~s lb/t:on of clinker) to '
8-20
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0.26 g/Mg of clinker (5.2 x 10'4 Ib/ton of clinker). The average
emission factor for all 19 facilities was 4.7 x 10"2 g/Mg of
clinker (9.3 x 10'5 Us/ton of clinker). These data are based on
the average of all test runs. - :
8.3 "PHOSPHATE ROCK PROCESSING ......
Phosphate rock, a calcium phosphate mineral known as apatite
(Ca10(P04)6F2) is mined and processed by beneficiation, drying or
calcining, and grinding.21 As a natural impurity in the
phosphate rock, cadmium emissions may occur during any thermal
processing of the rock. Florida ores can contain 2 to 15 parts
per million (ppm) of cadmium; North Carolina ores, 10 to 25 ppm;
Tennessee ores, 0.1 to 2 ppm; and western ores (mainly Idaho), 2
to 980 ppm with a median concentration of 200 ppm.21
While fertilizer production is the major, use for phosphate
rock, the rock can also be used to produce phosphoric acid and
elemental phosphorus. These industries are not considered part
of the phosphate rock"processing industry; however, because they
use phosphate rock as a raw material they are briefly summarized.
Phosphoric acid is produced by digesting the phosphate rock with
sulfuric acid, and pure phosphorus is manufactured in an electric
arc or blast furnace from phosphate rock and silica.110'111
A number of fertilizers are produced depending on the
phosphate content of the rock. These fertilizers are: normal
superphosphate, triple superphosphate; and ammonium phosphate.
No thermal processing is used in fertilizer production;
therefore, it-is not considered a significant source of cadmium
emissions. Additionally, no data are available that quantify
cadmium air emissions during the chemical reactions that produce
fertilizers. Since there is also no thermal processing during
8-21
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..... ' I »! 3
phosphoric acid production, this process is not considered to be
a. cadmium emission source.
: I .
Using an EAF in elemental phosphorus production is a thermal
treatment process and the EAF may be a cadmium emission source.
The rock is heated in a large furnace with "coke "and silica to
temperatures of 1300° to 1500«C (2372° to 2732°F) to produce
phosphorus vapor. Elemental phosphorus is condensed to a, liquid
in cooling towers with water sprays at 45° to 55 «c (113° to
Drying or calcining phosphate rock, are also thermal
treatment processes, and are considered cadmium emission sources
for phosphate rock processing. These potential emission sources
are discussed in more detail in the process description.
Table C-4 in Appendix C lists those companies, as of
January l, 1991, which mine phosphate rock and their annual
capacities. _In 1991, 154.5 million Mg (340 million tons) of'
phosphate rock were mined and 48.1 million Mg (106 million tons)-
were marketed after processing.^ Of that amount, Florida and
North Carolina produced 149.8 million Mg (330 million pounds).
The remaining 4.7 million Mg (10.3 million tons) were mined in
Idaho, Montana, Tennessee, and Utah.1^ Annual plant production
capacity was reported as 59.1 million Mg (130 million tons) in
1991.12
Known EAF operations that produce elemental phosphorus from
phosphate rock are in Pocatello, Idaho; Silver Bow, Montana; and
Soda "Springs, Idaho (Monsanto). These producers and their
capacities are listed in Table C-5 in Appendix C.
8-22
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8.3.1 Proceg.g Descriptipn90
Figure 8-3 provides a flow diagram for the overall
> processing of the rock for manufacturing. Before manufacturing
fertilizer or elemental phosphorus, the mined phosphate.rock must
be beneficiated, dried (or calcined), and ground. .
Beneficiation requires removing clay, sand, or organic
materials. Depending on where the rock was mined, it may need to
be segregated by certain sizes for washing and further grinding.
Once a particular size is reached, and all foreign materials have
been removed, a wet rock mill grinds the final slurry to the
consistency of fine beach sand. Hydrocyclones separate the
slurry into rock and clay; then the rock is filtered out and
allowed to dry in piles. Since this is a wet grinding process
with no thermal treatment, no cadmium emissions are anticipated.'
The organic content of the rock determines whether the rock
is dried in rotary or fluidized-bed driers, or heated in
fluidized-bed calciners. Rock free of organic contaminants is
dried in dryers at temperatures around 120°C (248°F). Rotary
driers are most commonly used and operate on natural gas or fuel
oil (Nos. 2 or 6). Rock with organic contaminants is heated to
760°C to S70°C (1400°F to 1598°F), usually in fluidized-bed
calciners. After heating or drying, the rock is conveyed to
storage silos on protected conveyors for processing in the
grinding mill, since dryers and calciners are heat processes, it
is believed there will be cadmium emissions from these sources.
After calcining or drying, the phosphate rock is sent to the
grinding mills. Roller or ball mills are used to grind calcined
phosphate rock into a fine powder; 60 percent (by weight) of this
powder typically passes through a 200-mesh sieve. A rotary, valve
feeds the rock into tnejrrinding mills, and circulating air
8-23
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streams remove the ground rock. Any remaining oversized
particles are sent back into the mill for regrinding. Final
product rock is separated by a cyclone for use in the next
manufacturing step, usually to make fertilizers.
While grinding is not a heat treatment step, it is believed
to be a source of fugitive particulate emissions from blown fine-
rock. This particulate may contain cadmium traces as noted
previously.
21
3.3. 2 Emission Control Measures90
Control equipment used for phosphate rock dryers usually
consists of scrubbers or electrostatic precipitators . Fabric
filters are not used. Venturi scrubbers with low pressure drops
(12 inches of water, or 3,000 Pascal, (Pa)) can remove 80 to
99 percent of the particulates that are 1 to 10 micrometers in
diameter; and for particulates lass than l micrometer, 10 to
80 percent may .be removed. Scrubbers with high pressure drops
(30 inches of water, or 7,500 Pa) can remove 96 to 99.9 percent
(1 to 10 micrometer particulates) or 80 to 86 percent (less than
1 micrometer particulates) . Electrostatic precipitators can
remove 90 to 99 percent of all particulates. If a wet grinding
process is used, a drying step and its particular emissions are
eliminated.
Calciners also use scrubbers and sometimes fabric filters.
One operating calciner uses an electrostatic precipitator.
Grinders use fabric filters and scrubbers to control emissions.
Operating the air circulating streams in grinders at negative
pressure avoids fugitive emissions 'of rock dust.
Material handling systems for ground rock, such as elevators
have a hi9h... .Potential for fugitive emissions.
8-25
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These emissions can-toe-controlled by covering and enclosing • -
conveyors, which have controlled discharge points. Material
transfer areas are hooded and the hoods -evacuated to a control
device. Storage silos or bins that are vented to the.atmqsphere ,
usually have fabric filters to control particulate emissions.
•Electric arc furnace emissions from elemental phosphorous
production are most often controlled by faiaric filters, although
venturi scrubbers and electrostatic precipitators can be used.113
i ( i
8-3.3 Emissions90
Phosphate Rock Processing--
The major cadmium particulate emissions from phosphate rock
processing (to produce fertilizers) are associated with the
processes of drying, calcining, and grinding. These emission
sources are shown by solid circles on Figure 8-3. Since
beneficiation involves slurries- of rock and water, there are no
significant cadmium particulate emissions.
i
No data were available concerning measured cadmium emissions
from drying, calcining and grinding. There are emission factors
in AP-42 for uncontrolled PM from these particular processes, but
no information is available on cadmium levels in this PM.
Therefore, these factors cannot be used to provide information on
potential cadmium emissions.
No specific data for cadmium emissions from phosphate rock
processing were found in the literature, arid no emission test
data were available to permit the calculation of cadmium
emissions.
•8-26
-------
Elemental Phosphorus Production--
Only one EAF reported cadmium emissions in the 1990 :TRI,
FMC Corporation in Pocatello, Idaho. Total releases of 3,966 kg
(8, 725 lb)- were reported; -emission factors -were used -to -estimate
nonpoint releases of 88 kg (194 lb) and the remaining point
releases of 3,878 kg (8,532 lb) were based -'on monitoring data.7
According to the Bureau of .Mines, a .number of EAF plants were
closed by 1991, and the 1990 TRI probably reflects this declining
production. 7' 112
8.4 CARBON BLACK PRODUCTION
Carbon black is an industrial chemical used as a reinforcing
agent in rubber products, such as tires, and as a black pigment
for printing inks, surface coatings, and paper and plastics.113
Cadmium may be a contaminant in the raw materials used and may be
emitted during carbon black production. Table 8-5 provides a
listing of facilities producing carbon black, their annual
capacity, and production processes. Total annual capacity as of
1991 was 1.47 million Mg (-1.62 million tons).12
8.4.1 Process Deacripf -i
Carbon black is produced by partial combustion of
hydrocarbons. The most predominantly used process (which
accounts for more than 98 percent of carbon black produced) is
based on a feedstock consisting of a highly aromatic
petrochemical or carbochemical heavy oil. Cadmium can be
expected to be present in the feedstock. Although the cadmium
content in the feedstock used to manufacture carbon black is not '
known, cadmium content in petroleum crude has been reported at
0.03 parts per million by weight (ppmwt) .US" Figure 8-4 contains
a flow diagram of this process.
8-27
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TABLE 8-5.. CARBON BLACK-PRODUCTION FACILITIES
Company
Waverty, West Virginia
Los Angeles, California
yioundsville, West Virginia
j Cabot Corporation
North:American Rubber Black Division
Chevron Corporation
Chevron Chemical Company, subsidiary
Olevins and Derivatives Division
Degussa Corporation
[Ebonex Corporation
J General Carbon Company
Hoover Color Corporation
JJ.M. Huber Corporation
jPhelps Dodge Corporation
Colombian Chemical Company, subsidiary
Sir Richardson Carbon & Gasoline Company
[Witco Corporation
Continental Carbon Company, subsidiary
Source: Reference 12.
*A - acetylene decomposition
C - combustion
F - furnace
T « thermal
bCapacfties are variable and based on SRI estimates as of January 1, 1991
8-28
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Three primary raw materials used in this process are,
preheated feedstock (either the petrochemical • oil or
carbochemical oil), which is preheated to a temperature between
1SO°C and 250°C (302°F and 482°F) , .preheated air, and .an - ........
auxiliary fuel such as natural gas. A turbulent, high- .
temperature zone is created in the, reactor -by combusting the "
auxiliary fuel," and the preheated oil feedstock is introduced in
this zone as an atomized spray." In this .zone of the reactor,
most of the oxygen would be used to burn the auxiliary fuel-,
resulting in insufficient oxygen to combust" the oil feedstock.
Thus, pyrolysis (partial combustion) of the feedstock is
achieved, and carbon black is produced. Most of the cadmium
present in the feedstock will be emitted as PM in the hot exhaust
gas from the reactor. .
The product stream from the reactor is quenched with water, "
and any residual heat in the product streaun is used to preheat
the oil feedstock and combustion air before recovering the carbon
in a fabric filter. Carbon recovered in the fabric filter is in
a fluffy form. The fluffy carbon black mciy be ground in a
grinder, if desired. Depending on the end use, carbon black .may
be shipped in a fluffy form or in the form of pellets.
Pelletizing is done by a wet process in which carbon black 'is
mixed with water along with a binder and fed into a pelletizer.
The pellets are subsequently dried and bagged prior to shipping.
8.4.2 Emission Control
During the manufacture of carbon black, high-performance
fabric filters are used in the oil furnace process to recover
additional carbon black; however, they also control PM emissions
from main process streams. Fabriq filters reportedly can reduce
PM emissions to levels as low as 6 mg/m3 • (normal m3) , and will be
used by facilities to- optimize their manufacturing performance.
8-30
-------
For oil furnaces, a cyclone can be used for particle
agglomeration upstream of the fabric filter. A single collection
system often serves several manifolded furnaces.
8.4.3 Emissions
The locations of cadmium particulate emission sources from
the oil furnace process are shown by solid circles in Figure 8-4.
The greatest release of cadmium occurs during pyrolysis of the
feedstock, making the reactor the major emission source during
production.
No data are available concerning cadmium emissions from the
thermal process. It is also not known how efficiently fabric
filters capture cadmium emissions." The only available data are
for emissions from the oil furnace process. These data show
cadmium emissions to be less than 5.0 x 10"5 kg/Mg
(1.0 x 10"4 Ib/ton) from the main process vent.116 This data
•source was a compilation of reported data and not test data; it
should be used with caution.
8.5 MOBILE SOURCES
Historically, the major emissions measured and regulated
under Title II of the Clean Air Act (CAA) from mobile sources are
CO, NOX, and hydrocarbons (HC). Emission factors for these
specific pollutants among the different motor vehicle classes are
compiled in AP-42, Volume II.117 Gasoline-powered motor, on-
road, light-duty vehicles comprise the most significant mobile
emission sources because of their large numbers. According to
the 1990 Statistical Abstract, 1988 nationwide registrations were
estimated to be 183.5 million cars, trucks, and buses. Of that
number, 140.7 million were passenger cars and 42.8 million were
trucks and buses.118 As of 1991, the total vehicle miles
8-31
-------
traveled (VMT). in the United States was 3,457,473 million
kilometers (2,147,501 million miles}.119
Potential•cadmium emissions result from, trace-quantities
present in the petroleum crude oil feedstock for fuel and motor
oil.115 Uncontrolled vehicle emissions have declined because
catalytic converters and unleaded gasoline are required along
with State-regulated inspection and maintenance programs.
Therefore, malfunctioning vehicles would be the emission source
from cadmium containing fuel or motor oil., Tire wear may also be
a source of cadmium emissions if any cadmium is present as an
impurity in the finished tire.
" ' • i '
A study conducted in 1979 characterized exhaust emissions
from noncatalyst- and catalyst-equipped vehicles under
malfunctioning conditions.120 NO cadmium was detected in the
exhausts. A more recent test was performed in 1989 to
characterize exhaust emissions of late model cars for toxip
pollutants listed or undergoing review for listing under
California's air toxics program.121 Particulate samples were
taken and analyzed for 31 trace metals, including cadmium. Of
the 31 trace metals, only 18 were detected in the exhaust;
cadmium was among the group of metals that was not detected. The
study used x-ray 'fluorescence for the metals analyses but did not
state a detection limit for cadmium. Based on this study, the
presence of cadmium in auto exhaust cannot be excluded but may be
present at a level below the unspecified detection limit of the
analytical method used in the study. '•
8-32
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SECTION 9
SOURCE TEST PROCEDURES'
9.1 INTRODUCTION
A number of methods exist to determine cadmium (Cd)
emissions from stationary sources. Several EPA offices and some
State agencies have developed source-specific or dedicated
sampling methods for Cd. Other industry sampling methods do
exist, but none of these methods have been validated and will not
be discussed in this section.
Subsequent parts of this section will discuss EPA reference
or equivalent sampling methods for Cd. Sampling methods fall .
into one of two categories: (l) dedicated Cd methods for
specific sources or (2) multiple metals sampling.trains that
include Cd for multiple sources. Each category of methods will
be described, differences among the methods will be discussed,
and a citation will be provided for more detailed information
about the methods.
Sampling methods included in this section were selected from
EPA reference methods, equivalent methods, draft methods, or
State methods. To be a reference method, a sampling method must
undergo a validation process and be published. To qualify as an
equivalent method, a sampling method must be demonstrated to the
EPA Administrator, under specific conditions, as an acceptable
alternative to the normally used reference methods. Also
included in this section is a draff method, which is under
development.
9-1
-------
9.2 MULTIPLE METALS SAMPLING TRAINS
9 • 2 • 1 Method 0012 -Methodology for fh?
-i nat- -i ~
-Metal
Emissions in Exhaust Gases from Pfa ^ -rdoug Wast-. P.
.Incineration and Similar Combug^irm Sources12 2
.This method was developed for the determination of a total
of 16 metals, including Cd, from stack emissions of hazardous
waste incinerators and similar combustion processes. Method 0012
allows for the determination of particulate emissions from these
sources. A diagram of a sampling train typical of a multiple
metals sampling train is presented in Figure 9-1.
i
. The stack sample is withdrawn isokinetically from the
source. Particulate emissions are collected in the probe and on
a heated filter; gaseous emissions are collected in a series of '
four chilled impingers: two contain an aqueous solution of
dilute HN03 combined with dilute H202 and two contain acidic
KMn04 solution. Sampling train components are recovered and
digested in separate front- and back-half fractions. Materials
collected in the sampling train are digested with acid solutions
using conventional Parr® Bomb, or microwave digestion techniques
to dissolve organics and to remove organic constituents that may
create analytical interferences. The detection limit for Cd by
ICAP is approximately 5 ng Cd/ml.
The corresponding in- stack method detection limit can be
calculated by using (i) the procedures -described in this method,
(2) the analytical detection limits described in the previous
paragraph, (3) a volume of 300 ml for the front-half and 150 ml
for the back-half samples, and (4) a stack gas sample volume of
1.25 m3:
9-2
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where:
A =
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analytical detection limit, /tg Cd/ml
volume of -sample" prior to aliquot 'for.- '.analysis, ml
sample volume, -dry standard cubic -meter (dscm)
^ D - in-stack detection limit, pg Cd/m3
9'2'2 Methodology for fhe Determination 9f Metal
Bxhaust Gage*? ^rom Hazardous
Tnci
Similar Combustion
The method was developed to determine the emissions of the
same metals as Method 0012 from hazardous waste incinerators and
similar combustion sources. This method is similar to SW-846
Method 0012 in sampling approach .and analytical requirements.
, . . , ., i
9-2-3 CARS Method 436-Determination of
from Stationary Source^124
Metal
This method is applicable for determining the emissions of
metals, including Cd, from stationary sources. This method is
similar to SW-846 Method 0012 in sampling approach and analytical
requirements. Method 436 suggests that the concentrations .of
target metals in the analytical solutions be at least 10 times
the analytical detection limits. This method may. be used in lieu
of Air Resource Board Methods 12, 101, 104, 423, 424, and 433.
9.2.4
Method 29-MPH-hodolQCTY
Combustion Sources
. This method is applicable for determining the emissions of
metals, including Cd, from stationary sources. This method is
9-4
-------
similar to SW-846 Method 0012 in sampling approach and analytical
requirements.
9.3 ANALYTICAL METHODS FOR DETERMINATION OF CADMIUM' -::v rr ' -
This section contains brief overview descriptions of the
five analytical techniques generally used for trace metal " • •
determinations: (l) inductively coupled argon plasma emission
spectrometry (ICAP), (2) direct-aspiration or flame atomic
absorption spectrometry (FAA), (3)' graphite-furnace atomic
absorption spectrometry (GFAA), (4) hydride-generation atomic
absorption spectrometry (HGAA), and (5) cold-vapor atomic
absorption spectrometry (CVAA). Each technique is discussed
below in terms of advantages, disadvantages, and cautions for
analysis.
The primary advantage of ICAP is that it allows simultaneous
or rapid sequential determination of many elements in a short
time. The primary disadvantage of ICAP is background radiation
from other elements and the plasma gases.- Although all ICAP
instruments utilize high-resolution optics and background
correction to minimize these interferences, analysis for traces
of metals in the presence of a large excess of a single metal is
difficult. An example would be traces of metals in an alloy or
traces of a metal in a limed (high calcium) waste. ICAP and
Flame AA have comparable detection limits (within a factor of 4),
except that ICAP exhibits greater sensitivity for refractories
(Al, Ba, etc.).
Flame AAg (FAA) determinations, as opposed to ICAP, are
normally completed as single element analyses and are relatively
free of interelement spectral interferences. Either a nitrous-
- oxide/acetylene or air/acetylene flame is used as an energy
diSS°Ciating the asPirated sample into the free atomic
9-5
-------
state, making analyte atoms available -for- absorption: of-ligiit.-
In the analysis of some elements, the temperature and type of ,
flame used is critical. If the proper flame and analytical
conditions are.not used, chemical and ionization interferences
can occur. :
Furnace AAfl (GFAA) replaces the flame with an
electrically heated graphite furnace.' Th& furnace allows for
gradual heating of the sample aliquot in several stages. Thus,
the processes of desolvation, drying decomposition for organic
and inorganic molecules and salts, and formation of atoms (which
must occur in a flame or ICAP in a few milliseconds) may be
allowed to occur over a much longer time period and at controlled
temperatures in the furnace. This allows the removal of unwanted
matrix components by using temperature programming and/or matrix
modifiers. The major advantage of this technique is that it
affords extremely low detection limits. It is the easiest^
technique to perform on relatively clean samples. Because this
technique is 39 sensitive, interferences can be a problem;
finding the optimum combination of digestion, heating times and
temperatures, and matrix modifiers can be difficult for complex.
matrices. Furnace AA, in general, will exhibit lower detection
limits than either ICAP or flame AAS.
AA (HGAA) utilizes a chemical reduction to reduce
and- separate arsenic or selenium selectively from a sample
digestate. The technique, therefore, has the advantage of being
able to isolate these two elements from complex samples, which
may cause interferences for the analytical procedures.
Significant interferences have been reported when any of the
following is present: (l) easily reduced metals (Cu, Ag, Hg) ,
(2) high concentrations of transition metals (>200 mg/L) , and
(3) oxidizing agents (oxides of nitrogen) that, remain .following
sample digestion.
' 9-6
-------
Cold-Vapor AA (CVAA) uses a chemical reduction to
selectively reduce Hg. The procedure is extremely sensitive but
is subject to interferences from some volatile organics,
chlorine, and sulfur compounds.
9.4 SUMMARY ' - . -'
All of the above source sampling methods collect a sample
for analysis of multiple metals, including Cd. Significant
criteria and characteristics of each method are presented in
Table 9-1. This table is a summary of information presented in
various methods. The major differences between the methods
involve: (l) the type of impinger solutions, (2) the amount or
concentration of impinger solutions, (3) the sequence and types
of sample train recovery solutions, and (4) the use and/or type
of particulate filter.
In assessing Cd emissions from test reports, the age or "
revision number of the method indicates the level of precision
and.accuracy of the method. Older methods are sometimes less
precise or accurate than those that have undergone more extensive
validation. Currently, EPA Method 301 from 40 CFR Part 63,
Appendix A can be used to validate or prove the equivalency of
new methods.
9-7
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SECTION 10
REFERENCES
5.
6.
7.
8.
9.
Toxic Chemical Release Reporting: Community Right -To-Know
Federal. Register 52(107): 21152-21208. June 4, 1987.
Hollander, M. L., and S. C. Carapella, Jr. Cadmium and
Cadmium Alloys. (In) Kirk-Othmer Encyclopedia of Chemical
Technology. Volume 4. M. Grayson, ed. A Wiley-
Interscience Publication, John Wiley and Sons "New York
NY. 1978.
Parker, P.D. Cadmium Compounds. (In) Kirk-Othmer
Encyclopedia of.Chemical Technology. Volume 4. 3rd ed.
M. Grayson, ed. A Wiley-Interscience Publication, John*
Wiley and Sons, New York, NY. 1978.
Cadmium Association/Cadmium Council. Technical Notes on
Cadmium. Cadmium in Alloys. Cadmium Association, London;
Cadmium Council, New York, NY. 1978.
Cadmium Association. Cadmium. The Quality Metal. Cadmium
Association, London, undated.
Llewellyn, T.O. Cadmium in 1991. Branch of Industrial
Minerals, Division of Mineral Commodities, Bureau of Mines
U.S. Department of the Interior, Washington, DC
January 1993.
U. S. Environmental Protection Agency.
•Inventory, Office of Toxic Substances.
January 1993.
1990 Toxic Release
Washington, DC.
U. S. Environmental Protection Agency. Compilation of Air
Pollution Emission Factors, AP-42, Fourth Edition,
Supplement E. U. S. Environmental Protection Agency,
Research Triangle Park, NC. October 1992.
XATEF.' Crosswalk/Air Toxic Emission Factor Data Base
Version 2 for 1992 update. Office of Air Quality Planning
and Standards, U. S. Environmental Protection Agency,
Research Triangle Park, NC. September 1992'.
10-1
-------
10,
XI.
12
13
14,
15
16,
17.
18-.
Emission Standards and Engineering Division. Cadmium -
Emissions from Cadmium Refining and Primary Zinc/Zinc -Oxide
Smelting -- Phase I Technical Report. EPA-450/3-87-011
Office of Air Quality Planning and Standards, .U. -S. "
Environmental Protection Agency, Research Triangle Park
North Carolina. -June 1987..
Jolly, J. H. Zinc. (In) Minerals Yearbook 1989
Volume I. Metals and Minerals. Bureau of Mines, U S
Department of the Interior, U. S. Government Printing
Office, Washington, D. C. 1991.
U i },,,,:',, i
SRI International. 1991 Directory of Chemical Producers:
United States of America.. SRI International, Menlo Park,
California. 1991.
JACA Corporation. Analysis and Alternatives - Air
Emissions Control Study - ASARCO Globe Plant, Denver
Colorado. Final Report. Prepared for the Colorado
Department of Health. August 6, 1992.
Radian Corporation. Background Information Document for '
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10-13
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-------
APPENDIX A
NATIONWIDE EMISSION ESTIMATES
-------
-------
EMISSIONS FROM CADMIUM PRODUCTION •
Cadmium Refining
Basis of Input Data
1. The 1990 TRI reported emissions for all' producers of
cadmium (see Table 4-3) to be 4.2. Mg H.6 tons).
2. Emissions reported in the .TRI may give abnormally high
values because the TRI data may'include unusual and
accidental releases. However, in the absence of other
data, the nationwide estimates will be based on these
data.
Cadmium Pigments Production
Basis of Input Data
1. The emissions reported in the 1990 TRI for producers of
inorganic pigments were 1.6 Mg (1.8 tons). These data
are presented in Table 4-8.
2. Emissions reported in the TRI may give abnormally high
values because the TRI data may include unusual and
accidental releases. However, in the absence of other
data, the nationwide estimates will be based on these
data.
Cadmium Stabilizers Production
The emissions reported in the 1990 TRI for cadmium
stabilizer producers were 3.3 Mg (3.7 tons). These data are
presented in Table 4-9.
Other Cadmium Compound Production
No emission factors are available for cadmium emissions from
this source.
A-l
-------
EMISSIONS- FROM MAJOR USES OF-GADMIIM
Secondary Battery Manufacture .
Basis of Input Pat;?
™r, ; emissions ^for all manufacturers
secondary cadmium batteries to be 0.32 Mg (0..35
• \
, i
2. .Emissions reported in the TRI my give abnormally hicrh
lSiILtaiareL^: TRI**t* may_ Inllude abnormal^nd5
accidental releases. However, in the absence of other
data the nationwide emissions presented in lection 3
are based on the 1990 TRI report. aeccion j
Cadmium Stabilizers for Plastics
The 1990 TRI reported emissions from 34 manufacturers of
formulated resins and plastic products to be 10 Mg (i i
see Table 5-4. Some of these facilities are likely also
cadmium-based pigments in the resins, but the TRI
b4tween ?he two
Cadmium Pigments in Plastics
Of custoni compound purchased resins reported
sr
A-2
_
-------
EMISSIONS FROM COMBUSTION SOURCES "- • • '- " -
Coal Combustion
Coal-Fired Utility Boilers--
Basis of Input Data
1. From Table 6-8, emission factor for bituminous coal
• . .combustion.» 3 .,0 x 10'J-J. kg/J and for anthracite coal
combustion » 7.3 x 10~15 kg/J.
2. Bituminous coal combustion systems controlled by ESP's
with an average cadmium control efficiency of
75 percent conservatively assumed.
3. Anthracite coal combustion systems uncontrolled.
4. Energy from coal combustion in utility sector from
Table 6-1.
Calculations
Annual Emissions
3.0 x 10
0.25
-14 '•
kg/J * 16.939 x 10lb J/yr
18
+ 7.3 x "10~15 kg/J * 0.018 x 1018 J/yr
127.17 Mg/yr = 140.18 tons/yr
Coal-Fired Industrial Boilers-
Basis of Input Data
From Table 6-8, emission factor for bituminous coal
combustion =• 3.0 x 10~±* kg/J and for anthracite coal
combustion = 7.3 x 10
•15
kg/J
No control of emissions from industrial boilers was
assumed.
Energy from coal combustion in industrial sector from
Table 6-1.
Calculations
Annual Emissions » 3.0 x 10~14 kg/J * 2.892 x 101S J/yr
+ 7.3 x 10~1S kg/J * 0.009 x 10iS J
-. 86.83 Mg/yr =» 95.71 ton/yr
J/yr
A-3
-------
Coal-Fired Commercial and ResidentialsBoilers-"-
Basis of Inp^t Data / . •;•-.••
1. From TahlA 6-8, emission
«.3.:a x 1-0~^4
- 7.3 x io"1^
°£ smissions fronl industrial boilers wag
Calculations
Annual Emissions
3.0 x 10 ^kg/J * 0.130 x 10-- J/yr
+ 7.3 x 10-I5kg/J * 0.032 x 101&J/yr
4.13 Mg/yr =4.55 tons/yr
Oil -Fired Utility Boilers--
:
Basis of Input
Due to insufficient data, air pollution control
Oil
from
Calculatjqna
Annual Emissions - 4.7 x lO'" kg/j * i.20l x 1018 J/yr
+7.1 x lO'13 kg/j * 0.091 x I0i6 J
6.29 Mg/yr . 6.93 tons/yr
Oil-Fired Industrial Boilers--
Basis Of Tnpnf;
J/yr
X' SusSon f"457 TSr&iB?0*f? dist"^« oil
combustion »7.lxlO"'1l= anC
i Hi1111 'I in nil i h i
A-4
-------
2.
3.
Air pollution control measures assumed to provide no
cadmium emission reduction.
Energy consumption from fuel oil combustion from
Table 6-1.
Calculations.
.Annual Emissions
4.7 x 10~1S kg/J * 1.245 x 1018 J/yr
+ 7.1 x 10'*5.kg/J .*.0.436 x 1018 J/yr .
8.95 Mg/yr =» 9.87 tons/yr
Oil-Fired Commercial/Residential Boilers--
Basis of Input Data
1. From Table 6-15, emission factor for distillate oil
combustion = 4.7 x 10"^ kg/J and for residual oil
combustion = 7.1 x 10~15 kg/J
2. Air pollution control measures assumed to. provide no
cadmium emission reduction..
3. Energy consumption from fuel oil combustion from
Table 6-1.
Calculations
Annual Emissions
4.7 x 10'15 kg/J * 1.395 * 1018 J/yr
+ 7.1 x 10'-15 kg/J * 0.255 x 1018 J/yr
8.37 Mg = 9.23 tons/yr
Wood Combustion in Boilers--
Basis of Input Data
1. Wood combustion rate in boilers is 1.0 x 1011 Btu/hr,
which is the same rate as 1980 given on p. 6-38.
Boilers assumed to operate at capacity, 8,760 hr/yr.
2. Heating value of wood is 4,500 Btu/lb based on midpoint
of range presented on p. 6-38.
3. Emission factor of 8.5 x 10"6 Ib/ton of wood burned.
4. No data available on control of cadmium emissions from
wood waste boilers.
A-5
-------
Calculation^
Annual Emissions
l1
1Q Bt-.ii/hr * 8.760 hr/y-r * 8 5
10
-6
Municipal Waste Combustors--
Basis of input
2.
3.
f°r Controlled systems contained
. avera5ed to obtain the following
"typical" emission factors:
Mass Burn - 5.3 g/Mg
Modular - 1.2 g/Mg
RDF - 4.4 g/Mg
Electrostatic precipitators achieve 95 percent removal
?|ray d3T?r ^sterns combined with f abriS f iSerfSr '
ESP s achieve about 99 percent removal. Duct sorbent '
infection systems combined with fabric filters or ESP's
also achieve about 99 percent removal.
The 1990 MWC processing rates are assumed to' be equal
to those presented in Waste Aag. November 1991 and
tabulated in the calculation table below 1
Calculations
Controlled Emissions
Annual Emissions
3 Process Rate * Emission Factor *
^
The calculated emissions are tabulated below:
(IPO-Efficiency)
100
A- 6
-------
Combustor
type
Mass Burn
Mass Burn
Mass Burn
Mass Burn
RDF
Modular
Total
Control
status3
U
"so
OSI
ESP
SO
ESP
Process
rate,
106 Mg/yr
0.517
7.190
1.077
13.806
2.809
0.630
Emission
factor, g/Mg
5.3
5.3
5.3
5.3
4.4
1.2
Control
efficiency,
%
0
99
99
95
99
95
Annual Emissions
Mg/yr
2.72
0.38
0.06
3.63
0.12 •
0.04
6.95
ton/yr
3.00
0.42
0.06
4.00
0.14
0.04
7.66
aSD =•• Spray dryer with either ESP or fabric filter
ESP = Electrostatic precipitator
DSI - Duct sorbent injection with either ESP or fabric filter
U = Uncontrolled
Sewage Sludge Incinerators --
Basis for Input Data
1.
2.
3.
Total sludge processed annually is 1.5 x 10s Mg
(see page 6-55)
From the Draft AP-42, Section 2.5, Sewage Sludge
Incineration, an average emission factor for units with
venturi/impingement control devices was 2.4 g/Mg
(4.8 x 10J Ib/ton).2 For other control devices, the
average emissions factor was 5.0 g/Mg
(1.0 x 102 Ib/ton).
In the.U.S., there are 210 sewage sludge incinerators;
of this population, 47 use venturi control devices,
97 use other control devices, and no information was
available for 66 units.3 Of the 144 units for which
data are available, 47/144 or 33 percent use venturi
controls and 97/144 or 67 percent use other controls.
This percentage distribution is assumed to be
representative for all 210 units.
Calculations
Annual Emissions
1.5 x 10'f Mg/yr * 0.33 * 2.4 g/Mg +
1.5 x 10'6 * 0.67 * 5.0 g/Mg = 6.2 Mg/yr
- 6.9 tons/yr
A-7
-------
Medical Waste Incinerators --
Basis of Input;,'
^From unpublished data contained in the medical waste
arlTIofx ^ISMb/Ckg5OUnd filSS' annual Process rites
i ?3?*2 ?n£ i, Mg/yr for P^hological waste and
1.431 x 10 b Mg/yr for mixed medical waste.
From ^bla6-23 "typical" uncontrolled emission factors
«??* i • ? r mixed waste and 0.18 g/Mg for
pathological waste. a
3 '
systems can achieve at least 97"percent"*controrihile
wet systems can achieve about 38 percent control
Calculations
Annual Emissions
2.5 g/Mg * 1.43 x 10J> Mg/yr * 0.97
+ 2.5 g/Mg * 1.43 x 10° Mg/yr * 0.03 * 0.45 * (i-o 97)
* 2:?.g&Vo?!o: i°i>£^ <°-03 * »•» *
-------
Calculations
4.
The sum of the cadmium emissions (for both, nonpoint and
point sources) for all 3 facilities is 14.3 Mg (15.80 tons)
which is also the estimated nationwide annual emission rate
of cadmium from primary lead smelting facilities.
Primary Copper Smelting -...-•
Basis of Input Datai - • ' • . . .
Data in 1990 TRI. Pour facilities reported total
facilitywide cadmium emission rates for 1990. These data
are presented in Table 7-5.
Calculation^
Four facilities reported cadmium emission rates for 1990 as
y??SifeS.??de* Superfund ^endments and Reauthorization Act
{SARA) Title III provisions. The sum of the cadmium
emission rates reported by the 4 facilities is 5.6 Mg
(6.2 tons) . 3
Primary Zinc Smelting
Basis of Innut Data
Data in 1990 Toxic Release Inventory System (TRIS) ' There
are 4 primary zinc smelting facilities within the U.S. All
4 tacilities reported cadmium emissions resulting from all
??S?ati°?S f?r the year 199°- Tnese *«» are Presented in
Table 7-8. Accuracy of these data cannot be verified
Therefore, the sum of the cadmium emissions for all 4
facilities will be the estimated nationwide cadmium emission
Cal cula t i ona
The sum of the cadmium emissions (for both, nonpoint and
SSirh ?°ur?es) Jor aH 4 facilities is 5.7 Mg (6.3 tons),
of SrfiJ, J° estimated nationwide annual emission rate
of cadmium from primary zinc smelting facilities.
Secondary Copper Smelting
Basis of Input Data
fiSeill?vi?S2 "5 ^"°
-------
reported cadmium emission data for 1989.
presented in Table 7-11.
These data are
Calcula t i ons
The TRI data base contains emissions reported for 1990 by 3
facilities. Another facility (Southwire Co.) reported data
for 1989. For this study, it is assumed that the cadmium
emissions at Southwire Co. for 1990 was the same as that
reported for 1989.. Total .emissions- for the four facilities
were 1.2 Mg (1.3 tons) . '.-'.'
There are a total of 6 secondary copper manufacturing
facilities in the U.S. Raw materials used at these
facilities can vary significantly. Therefore, it is not
valid to assume that the cadmium emission rate is directly
proportional to the plant capacity. This is confirmed fay
the fact that the cadmium emission factors (see Table below)
for the 4 facilities range between 4.1 x 10"5 and 0.028
kg/Mg of product.
Facility
Cadmium emission,
' factor, kg/Mg
Chemetco
Franklin Smelting & Refining
Gaston Recycling Inds.
Southwire Company
0.005
'0.028
4.1 x 10"5
5.43 x 10."4
The cadmium emission factors reported above have been
estimated using the TRI data in Table 7-11 and plant
capacity data contained in Table 7-10,,
Cadmium emission factors are not available to separately
estimate the emission rates at the 2 facilities for which
there are no TRI data. Therefore, it is conservatively
assumed that the emission factor of 0.028 kg/Mg estimated
for_Franklin Smelting & Refining Co. may be applicable for
estimating cadmium emissions at the remaining 2 facilities.
This approach is conservative because the emission factor
chosen is the highest of the 4 factors estimated above
Based on this emission factor and the capacities given in
Table 7-10, the total cadmium emission rate for the 2
facilities is estimated to be 3.2 Mg (3.5 tons). Thus,' the
nationwide annual cadmium emission rate for all 6 "facilities
is estimated to be 4.4 Mg (4.8 tons).
A-10
-------
5.
Secondary Zinc Recovery from Metallic Scrap
Basis of Incut Data
1.
Cadmium emission factors from SPECIATE data base given
'in Table 7-13.
2. Figure 7-6 containing the process, flow diagram.
Calculations
Major process steps are pretreatment of scrap, melting the
sweated scrap and refining/alloying. Each of these steps
can be performed in various ways. Because-the specific
process description for each of the 13 plants listed in
Table 7-12 is not known, we need to create a conservative
model process flow scheme.
Refer to Figure 7-6. For this study, assume that all plants
produce secondary zinc from die cast products, residue
skimmings,_ and other mixed scraps. Pretreatment of these
materials is carried put in one of 4 ways as shown in Figure
7-6. Of the 4 cadmium emission factors corresponding to
these 4 pretreatment methods, the emissions factor for
reverberatory sweat furnace (general metallic scrap) is the
highest. This emission factor is 0.01232 kg/Mg of zinc
produced. Therefore, it is assumed that all 13 plants use
the reverberatory sweat furnace for pretreatment. *
Next, the melting is carried out in one of 4 ways. However,
Table 7-13 does not contain cadmium emission factors for
melting operations. Therefore, it is assumed that all 13
plants also carry out the melting in reverberatory melting
kettles and the cadmium emission factor for melting is the
same as that, for pretreatment (0.01232 kg/Mg of zinc
produced).
Finally, zinc ingot is produced in one of 2 ways. The
naSS^ f^fl31011 factor for both methods is reported to be
u. uuuyi Jcg/Mg.
Therefore, the total cadmium emission factor for the three
manor processing steps is estimated to be 0.02555 kq/Mcr of
zinc produced. The total zinc production capacity for all
13 plants is reported to be 58,000 Mg. Therefore, the
nationwide annual cadmium emission rate for all 13 plants
fe?Ui^i:?? J0?11 fc?e ^coprocessing steps is estimated to be
j. o a Mg 11.7 tons) .
A-11
-------
•6.
Secondary Zinc Recovery from EAF Dust:
Basis of Input Data.
Cadmium emission factor data for recovery of zinc from EAF
dust -are limited. Cadmium emission factor for only one
processing step using the flame reactor is available. The
emission factor is reported to be 2.1 x 10~4 kg/Mg of EAF
dust processed. Therefore, for this study, it is assumed
that all facilities producing zinc from EAF dust use the
flame reactor. . -
Calculations :
Table 7-14 presents the EAF dust processing capacity for all
9 facilities in the U,S. The total E!AF dust processing
capacity is 533,200 Mg/yr. If all this dust is processed in
a flame reactor equipped with a fabric filter, the
nationwide annual cadmium emission rate resulting from this
processing step is estimated to be 112 kg (246 Ib). It must
be noted that other major processing step, the calcining
kiln, will also emit cadmium. However, the cadmium emission
rate corresponding to this step cannot be estimated due to •
the lack of emission factor data.
EMISSIONS FROM MISCELLANEOUS SOURCES
Iron and Steel Production
The 1990 TRI reported emissions to be i.4 Mg (1.5 tons)
Because the TRI data presented in Table 8-3 represent only a
portion of the iron and steel production facilities in the U.S.,
these emissions should be regarded as minimum levels.
Portland Cement Production
Basis of Input Data
1*. The 1990 total production of cement was 70.6 x 10s Mg
(77.8 x I0b tons) of which 95.7 percent was portland
cement. Total production of portland cement was
67.5 x 10b Mg (74.5 x 106 tons). Portland cement is
96 percent clinker.
2. From Table C-3, the average emission factor is
4.7 x 10'^ g/Mg (0.93 x 10'4 Ib/ton) of clinker
produced. This emission factor is based on the average
of all test runs in Table C-3.
A-12
-------
Calculations;
Annual emissions:
67.5 x 106 Mg * 0.96 * 4.7 x 10'2 g/Mg = 3.0 Mg/yr =
3.3 tons/yr a/.r
Phosphate Rock Processing
-No emission factors are available for cadmium emissions from
this source. . .
Carbon Black Production
Basis of Input Data
1. The 1990 total capacity for carbon black production was
1.47 x 10b Mg (1.62 x 10s tons).* No data were
available for actual production of carbon black in
J>«7 y w *
2. An emission factor of 5 x 10'5 kg of Cd/Mg of carbon
black (l x 10'4 Ib/ton) is used.3
3. The emission factor is based only on the oil-furnace
process which accounts for 99 percent -of all carbon
black production.
4.
Cadmium emissions are based on production capacity and
not actual production. Use of actual production data
would show a lower value for cadmium emissions.
Calculations
Annual emissions = 5 x 10 ~5 kg/Mg * 1.47 x 106 Mg =
0.07 Mg/yr =0.08 ton/yr
Mobile Sources
t-h-ic,
UXliS
fact'ors are available for cadmium emissions from
A-13
-------
TABLE A-l. SUMMARY OF CADMIUM EMISSION FACTORS AND SCC
1) SCC number
11-01-001
1-01-002
1 1-02-001
Jj 1-02-002
1 1-03-001
1 1-03-002
1-01-004
1-01-005
1-02-004
1 1-02-005
1 1-03-004
1 1-03-O05
1-02-009
|5-01-001-02
J5-01-001-02
5-01-001-02
5-01-001-03
J5-01-001
[5-01-005-15
5-01-005-16
5-01-005-05
5-O1-005-05
5-01-005-05
5-O1-005-05
3-03-010-01
3-03-010-02
J3-03-O10-03
J3-03-010-04
J3-03-010-06
|3-03-010-08
3-03-010-09
3-03-010-10
3-03-010-11
3-03-010-12
Source description
Coal combustion: Utility boilers
Coal combustion: Utility boilers
Coal combustion: Industrial boilers
Coal combustion: Industrial boilers
Coal combustion: Commercial & residential
Coal combustion: Commercial & residential
Oil combustion: Utility boilers
Oil combustion: Utility boilers
Oil combustion: Industrial boilers
Oil combustion: Industrial boilers
Oil combustion: Commercial & residential
Oil combustion: Commercial & residential
Wood combustion: Boilers
Municipal waste combustors: Mass bum
Municipal waste combustors: Mass burn
Municipal waste combustors: Mass bum
Municipal waste combustors: RDF
Municipal waste combustors: Modular
Sewage sludge incinerators
Sewage sludge incinerators
Medical waste incinerators: mixed waste
Medical waste incinerators: mixed waste
Medical waste incinerators: mixed waste
Medical waste incinerators: pathological waste
Sintering: single stream
Blast furnace operation
Dross reverberatory furnace
Ore crushing
intering: dual stream feed end
lag fume furnace
Lead dressing
Raw material crushing and grinding
Raw material unloading
Raw material storage piles
Control
sitatus*
U
c
U
U
U
U
U
U
U
U
U
U
U
U
C9596
C9956
C
C
C
C
U
C3896
C97%
U
C
C
C
c
c
c
c
- c
c
c
Cadmium emission factor
7.3xlO'15kg/J produced
7.5x10' 15 kg/J produced
7.3x10- 15 kg/J produced
3.0xlO'14 kg/J produced
7.3xlO'15 kg/J produced
S.OxlO"14 kg/J produced
7. 1x10' 15 kg/J produced
4.7xlO'15 kg/J produced
7. 1x10' 15 kg/J produced
4.7xlO"15 kg/J produced
7. IxlO'15 kg/J produced
4.7xlO'15 kg/J produced
4.3XMT6 kg/Mg burned
5.3 g/Mg waste
0.26 g/Mg waste
0.05 g/Mg waste
0.04 g/Mg waste
0.30 g/Mg waste
2.4 g/Mg sludge
5.0 g/Mg sludge
2.5 g/Mg burned
1.6 g/Mg burned
0.075 g/Mg burned
0.18 g/Mg burned
0.7 kg/Mg cone, ore
20.9 kg/Mg cone, ore
0. 12 kg/Mg cone, ore
8.3 g/Mg ore
4.84 kg/Mg cone, ore
1.8 g/Mg lead produced
1.0 g/Mg lead produced
23 g/Mg lead produced
1.7 g/Mg raw material
1.3 g/Mg raw material
A-14
-------
TABLE A-l. (continued)
SCC number
3-03-010-13
3-03-010-14
3-03-010-15
3-03-010-16
3-03-010-17
3-03-010-19
3-03-010-20
3-03-010-21
3-03-010-22
3-03-010-23
3-03-010-24
3-03-010-25
3-03-010-26
3-03-005-O3
3-03-005-04
3-03-005-05
3-03-005-06
3-03-005-07
3-03-005-O9
3-03-005-10
3-03-005-12
3-03-005-13
3-03-005-14
3-03-005-15
3-03-005-16
3-03-005-17
3-03-005-22
3-03-005-24
3-03-005-25
3-03-005-26
Source description
Raw material transfer
Sintering charge mixing
Sinter crushing/screening
Sinter transfer *•
Sinter fines return handling
Blast furnace tapping (metal and slag)
Blast furnace lead pouring
Blast furnace slag pouring
Lead refining/silver retort
Lead casting
Reverberatory or kettle softening
Sinter machine leakage
Suiter dump area
Reverberatory smelting furnace after roaster— ESP
Converter (all configurations)-ESP
Fire (furnace) refining— ESP
Ore concentrate dryer— ESP
Reverberatory smelting furnace with ore
charging(without roasting)— ESP
Fluidized-bed roaster— ESP
Electric smelting furnace— ESP
Flash smelting
Roasting: fugitive emissions— ESP
Reverberatory furnace: fugitive emissions— ESP
Converter: fugitive emissions
Anode refining furnace: fugitive emissions— ESP
Slag-cleaning furnace: fugitive emissions— ESP
Slag-cleaning furnace— ESP
AFT MHR+RF/FBR+EF
Fluidized-bed roaster with reverberatory furnace
+ converter— ESP
Concentrate dryer with electric furnace, cleaning
umace and converter— ESP
Control
status2
C
C
C
C
C
C
C
C
C
C
C
C-
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Cadmium emission factor
2. 1 g/Mg raw material
9.4 g/Mg raw material
34.2 g/Mg sinter
4.6 g/Mg sinter
0.205 kg/Mg suiter
3.6 g/Mg lead produced
21.2 g/Mg lead produced
0.4 g/Mg lead produced
41 g/Mg lead produced
19.8 g/Mg lead produced
0.07 kg/Mg lead produced
12.6 g/Mg suiter
0.23 g Mg suiter
2.5 g/Mg cone, ore
1.8 g/Mg cone, ore
0.5 g/Mg cone, ore
0.5 g/Mg cone, ore
2.5 g/Mg cone, ore
2.8 g/Mg cone, ore
5 g/Mg cone, ore
1.16 kg/Mg cone, ore
0. 13 g/Mg cone, ore
.6 g/Mg cone, ore
4. 1 g/Mg cone, ore
0.025 g/Mg cone, ore
.4 g/Mg cone, ore
.5 g/Mg cone, ore
.09 kg/Mg cone, ore
.8 g/Mg cone, ore
.5 g/Mg cone, ore
! : .
A-15
-------
TABLE A-l. (continuejd)
|j SCC number
|3-03-005-27
|3-03-030-03
[J3-03 -030-06
M3-03-O30-08
13-03-030-09
|3-03-030-10
|3-03-030-11
|3-03-030-12
83-04-008-01
|3-04-008-02
|3-04-008-03
|3-O4-008-05
IJ3-04-O08-06
|3-04-008-09
JJ3-04-008-10
13-04-008-11
J3-04-008-12
J3-O4-008-24
J3-04-008-28
3-04-008-34
3-04-008-38
3-04-008-51
13-04-008-52
3-04-008-54
J3-04-008-55
1 3-04-008-62
J3-04-O08-63
__:
|3-04-008-64
3-04-008-65
3-O4-008-72
Source description
Concentrate dryer with flash furnace and
convertor— ESP
Suiter strand
Electrolytic processor
Fluidized-bed roaster ' .
Raw material handling and transfer
Sinter breaking and cooling
Zinc casting
Raw material unloading
Retort furnace
Horizontal muffle furnace
Pot furnace
Galvanizing kettle
Calcining tHln
Rotary-sweat furnace
Muffle-sweat furnace
Electric resistance sweat furnace
Crushing/screening of zinc residues
Kettle-sweat furnace (general metallic scrap)
Reverberatory sweat furnace (general metallic
scrap)
Kettle-sweat furnace (general metallic scrap)
Reverberatory sweat furnace (general metallic
scrap)
Retort and muffle distillation: Pouring
Retort and muffle distillation: Casting
Retort distillation/oxidation
Muffle distillation/oxidation
Rotary sweating
Muffle sweating
Kettle (pot) sweating
Electric resistance sweating
Retort and muffle distillation
Control
status*
G
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Cadmium emission factor
rt e
O.5 g/Mg cone, ore
0.99 kg/Mg cone, ore
33 g/Mg cone, ore
23.8 kg/Mg cone, ore
43.9 g/Mg raw material
16.5 g/Mg sinter
27.5 g/Mg zinc produced
4.4 g/Mg raw material
18.1 g/Mg zinc produced
17.3 g/Mg zinc produced
0.04 g/Mg zinc produced
1.9 g/Mg zinc used
34.3 g/Mg zinc produced
6.9 g/Mg zinc produced
8.2 g/Mg zinc produced
3.9 g/Mg zinc produced
1.6 g/Mg residue
4.2 g/Mg zinc produced
5.0 g/Mg zinc produced
9.6 g/Mg zinc produced
2,3 g/Mg zinc produced
.23 g/Mg zinc produced
.12 g/Mg zinc produced
1.6 g/Mg zinc oxide
1.6 g/Mg zinc oxide
.35 g/Mg zinc produced
.41 g/Mg zinc produced
.22 g/Mg zinc used
.20 g/Mg scrap
:9 g/Mg zinc produced
A-16
-------
TABLE A-l. (continued)
SCC number
Source description
Control
status*
Cadmium emission factor
3-04-008-73
Casting •
0.005 g/Mg zinc produced
3-05-006-06
Portland cement production; dry process
.7xlO'2 g/Mg produced
3-05-007-06
Portland cement production; wet process
C
7xlO~2 g/Mg produced
3-01-005-04
Carbon black production: oil furnace
5x10° kg/Mg produced
aU = uncontrolled; C = controlled.
A-17
-------
REFERENCES FOR APPENDIX A
1. Kiser, J. V. L., and D. B. Sussman, Municipal Waste
Combustion and Mercury: The Real Story. Waste Age, November
1991, Pp. 41-44.
2. U. S. Environmental Protection Agency. Emission Factor
Documentation for AP-42 Section 2.5, Sewage-Sludge
Incineration. U. S. Environmental Protection Agency,
• Research Triangle'Park, NC.July 1993.
. • i
3. U. S. Environmental Protection Agency. Locating and
Estimating Air Emissions From Sewage Sludge Combustors. EPA
Report No. EPA-4SO/2-90-009. U. S. Environmental Protection
Agency, Research Triangle Park, NC. May 1990.
4. SRI International. 1991 Directory of Chemical Producers:
United States of America. SRI International, Menlo Park,
California. 1991.
5. Serth, R. W., and T. W. Hughes. Polycyclic Organic Matter
(POM) and Trace Element Contents of Carbon Black Vent Gas.
Environ. Sci. Technol., 14(3): 298-301. 1980.
A-18
-------
APPENDIX B
SUMMARY OF COMBUSTION SOURCE CADMIUM EMISSION DATA
-------
-------
Industr
v
TABLE B-1. SUMMARY OF COAL COMBUSTION EMISSION DATA
Facility
' Control
status0
Coal
Emission factor
kg/1015 J
Mean
Range
lb/1012 Btu
Mean
Range
se
PC/DB
ESP
«T
B
1.1
-'2.6
U
PC/DB
WS
B
0.52
1.2
U
PC/DB
MP/ESP
B
0.82
1.9
U
PC/DB
MP/ESP
0.60
1.4
U
PC/DB
ESP
B
11
4.9-23
26
11-53
U
PC/DB
UN
59
49-72
140
110-170
U
PC/DB
ESP
2.8
6.6
U
PC/DB
ESP
B
4.2
9.8
U
'PC/DB
ESP
B
1.6
3.8
U
PC/DB
UN
B
18
41
U
PC/DB
UN
5.2
12
U
PC/DB
UN
B
4.7
11
U
PC/DB
ESP
1.9
4.5
U
PC/DB
ESP
B
3.1
7.1
U
PC/DB
UN
B
4.3
10
U
PC/DB
UN
B
4.0
9.2
U
PC/DB
UN
B
4.3-6.0
10-14
U
PC/DB
ESP
B
<2.0
:4.6
U
PC/DB
ESP/W
S
B
<2.0
<4.6
U
PC/DB
MP
B
130
59-210
290
140-490
U
PC/DB
MP/ESP
B
20
46
U
PC/DB
VS
B
0.84
2.0
U
PC/DB
PC/DB
PC/DB
ESP
MP
UN
3
B
13
18
0.095-0.26
6.5-24
10-32
31
42
0.22-0.60
15-56
24-74
B-1
-------
TABLE B-1. (continued)
I Industr
8 v
I sector3
1 u.
i u
8 u
1 U
1 U
U
U
i U •
U
i U
i U
U
8 u
U
U
u
U
V U
U
1 U
1 U
I U
1 u
1 u
Facility
tvoeb
PC/WB
PC/WB
PC/WB
PC/WB
PC/WB
PC/WB
CY
CY
CY
CY
CY
CY
CY
S
S
S
CY
CY
PC
PC
NA
NA
PC/DB
PC/DB
PC/DB
Control
status0
MP/ESP
ESP
ESP
VS
ESP
ESP
ws
ESP
ESP
ESP
ESP
UN
ESP
FF
MP
MC
UN
WS
VS
ESP
ESP
ESP
MC
MC
ESP
Coal
- WPP.
d
B .
.B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
SB
SB
SB
SB
SB
SB
L
L
L
Emission factor
kg/1015 J
Mean
0.82
0.24
0.27
0.037
0.60
1.1
210
1.3
0.47
0.15
0.47
12
0.34
0.14
1.8
9.5
1,900
210
1.7
<0.17
0.17
0.73
11
2.2
<1.5
Range
..
..
—
_
—
_
~
_
__
„
..
9.5-15
0.30-0.39
..
..
„
..
__
„
_
_
„
M
V •»
».
lb/1012 Btu
Mean
1.9
0.56
0.63
0.086
1.4
2.6
490
3.0
1.1
0.35
1.1
28
0.80
0.33
4.2
22
4,400
490
4.0
<0.40
0.39
1.7
26
5.1
<3.5
Range
-
-
-
-
-
22-35 '
0.70-0.90
I
II
I
I
J
J
I
I
J
J
J
I
i.
B-2
-------
TABLE B-1. (continued)
B-3
-------
TABLE B-1. (continued)
Industr
v
sector3
I
I
I
!
I
I
I
I
I
I
C
C
C
C
C
C
C
R
R
R
R
Facility
tvoeb
OS .
OS
SS
SS
SS
SS
SS
SS
SS
SS
SS
PC/DB
PC/DB
SS
OS
S
S
S
NA
NA
S
S
Control
status0
UN
MP
UN
ESP
UN
ESP
UN
UN
MP/ESP
UN
MP/ESP
UN
MC/WS
MP
MP
UN
UN
UN
UN
UN
UN
UN
Coal
tvne
d
B
B
B
B
B
B
SB
SB
SB
SB
SB
B
B
B
B
A
A
A
B
B
B
B
Emission factor
kg/1015 J
Mean
43
24
5.6
0.56
4.7
1.8
6.0
34
2.5
120
6.0
5.5
0.15
2.4
0.52
0.99
1.5
0.60
67
13
3.8
<19
Range
—
1 9?2£»
—
—
..
..
2.1-9.9
..
...
_.
..
..
...
..
..
—
..
0.
„
..
«
—
lb/1012 Btu
Mean
100
56'
13
1.3
11
4.2
14
78
5.7
290
14
13
0.35
5.6
1.2
2.3
3.5
1.4
160
31
8.9
<44
Range
„
44-67
...
'..
'„
'„
4.9-23
..
„
i—
t»
•••
__
..
..
__
,-
<•••
.•
-—
__
--
aU 3 utility, I = industrial, C = commercial, R = residential.
PC a pulverized coal, DB = dry bottom, WB = wet bottom, CY = cyclone, NA = not available,
SS = spreader stoker, OS =* overfeed stoker, S » stoker.
B-4
-------
CESP= .electrostatic precipitator, WS = wet scrubber, MP = mechanical precipitation device,
UN = uncontrolled, VS = venturi scrubber, FF = fabric filter, MC = multiclone, CY = cyclone.
B = bituminous, SB = subbituminous, L = lignite, A = anthracite.
B-5
-------
TABLE B-2. SUMMARY OF MUNICIPAL WASTE COMBUSTOR EMISSION DATA
Facility name
Adirondack (Boiler A)
Adirondack (Boiler B)
Adirondack (Boiler B)
Adirondack average
Camden (Unit 1)
Commerce
Commerce •
Commerce average
Quebec City - Pilot
Quebec City - Riot
Quebec City - Riot
Quebec City - Riot
Quebec City - Riot
Quebec City - Riot
Quebec City average
Vancouver
— — ^ «^ .
Combustor
type3
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
Control
technology'3
u
U
U
U
U
DIM ^
A
UN
UN
UN .
UN
'UN
UN
UN
UN
UN
UN
Concentration
fjg/dscm @ 7% O7C
328
•J^mQ
659
439
475
- ™T » *J
71O
/ 1 W
960
1 ,600
1,280
1 OOO
I fWWW '
1 SOO '
1 f«JWV/ ,
1,200
1 30O
• t w WVy
1 TOO
I r 1 W
1 2OO
I f«— v/V/
1 ,220
1,200
B-jS
I
-------
TABLE B-2. (continued)
Facility name
Babylon
Babylon
Babylon
Babylon average
Bridgeport . . .
Bridgeport
Bridgeport
Bridgeport average
Bristol
Bristol
Bristol
Bristol average
Commerce
Commerce
Commerce average
Fairfax
Fairfax
Fairfax
Fairfax
Fairfax average
Gloucester
Gloucester
Gloucester
Glouster average
Hempstead
Hempstead
Hempstead
Hempstead average
Kent
Kent
Kent average
Long Beach
Marion County
Stanislaus County
Stanislaus County
Stanislaus County
Stanislaus County average
Combustor
type3
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
' MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
Control
technology'3
SD/FF
SD/FF
SD/FF..
SD/FF
SD/FF
SD/FF
SD/FF
. SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF .
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
• SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
Concentration
/t/g/dscm @ 7% 0?c
1.00
5.00
bd
. MV<
2 00
bd
. aa ' .
4 00
bd
uu
1.33
2.00
1.00
2.00
1 67
0.400
2 OO
£mt\J\J 1!
1 .20
9.00
6.00
6.00
5.00
6 SO I
\Jt%J\J _ II
bd
II
bd
bd
O OO
*^«WW II
bd
I
bd
bd
0.00
4.00
4.00
4.00
180
3 OO
w>WW II
2 OO
*B«WW |l
2 OO
2 00
-------
TABLE B-2. (continued)
1
I) Facility name
1 Adirondack (Boiler A)
I] Adirondack (Boiler B)
II Adirondack (Boiler B)
| Adirondack (Boiler B)
| Camden (Unit 1)
Charleston (Units A & B) •
1 Charleston (Unit Al
I] Charleston (Unit B)
[I Charleston average
Haverhill
Haverhill
Haverhill
Haverhill average
Millbury
I Millbury
I Millbury
| Millbury
j| Millbury
I Millbury
Millbury
Millbury average
| Portland
1 Portland
| Portland average
Pfnellas County
Tulsa
Tuisa
Tulsa average
Vancouver
Dutchess County
Dutchess County
Dutchess County average
Dayton
] Dayton
I Dayton
Dayton
Dayton
| Dayton average
Dayton
Dayton
| Dayton average
Dayton
Combustor
type3
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
' MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/WW
MB/RC
MB/RC
MB/RC
MB/REF
MB/REF
MB/REF
MB/REF
MB/REF
MB/REF
MB/REF
MB/REF
MB/REF
MB/REF
Control
technology13
- SD/ESP
SD/ESP
SD/ESP
SD/ESP
SD/ESiP
SD/ESiP
SD/ESP
SD/ESP
SD/ESiP
SD/ESP
SD/ESP
SD/ESP
SD/ESP
SD/ESP
SD/ESP
SD/ESP
SD/ESP
SD/ESP
SD/ESP
SD/ESP
SD/ESiP
SD/ESP
SD/ESP
SD/ESP
ESP
ESP
ESP
ESP
DSI/FF
DSI/FF
DSI/FF
DSI/FF
UN
UN
UN
UN
UN
UN
ESP
ESP
ESP
DSI/ESF
Concentration
fjg/dscm @ 7% Ooc
574
74 8
131
87.7
217
• 1
723
457
498
559
38.0
18.0
10.0
22.0
13.0
22.0
• 32.0
6.00
18.0
7.00
1 1 .0
,
15.6
4.00
4.00
4.00 ||
8.00
390
140
265 I
4.00 I
3.00 I
3.00
3.00 -
1,200
1 , 1 00
1,950
1,300
1 ,500
1,410
30.0
19.0
24.5
11.0
B-8
-------
TABLE B-2. (continued)
Facility name
Biddeford
Mid-Connecticut
Mid-Connecticut
Mid-Connecticut
Mid-Connecticut
Mid-Connecticut
Mid-Connecticut average
Biddeford
Mid-Connecticut
Mid-Connecticut
Mid-Connecticut
Mid-Connecticut
Mid-Connecticut average
Semass
Semass
Semass average
Detroit
Detroit
Detroit
Detroit average
Albany
St. Croix
Dyersburg
N. Little Rock
Ban-on County
Oneida County
^^^^"""^^^""^^^"""^^^•'•^^^^^^^^""•^^S^SiSSI^HEBSS^SHS^SS^^E
Combustor
type3
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
RDF
MOD/EA
MOD/SA
MOD/SA
MOD/SA
MOD/SA
Control
technology'5
UN
UN
UN
UN "
UN
UN
UN
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/FF
SD/ESP
SD/ESP
SD/ESP
ESP
ESP
ESP
ESP
ESP
DSI/FF
UN -
UN
ESP
ESP
=— — — — — —
^ag^^a^a:^ aas^a^^^saa
Concentration
/t/g/dscm @ 7% 02C
1,100
ROD
Cfi7
1,100
600
617
677
bd
bd
bd
hri
bd
0.00
10.0
7 00
8.50
hrl
hrl
hH
0.00
33.7
2.00
238
360
220
920
erivedfre , cWa"' = REF - refrac«»Y wall, RDF = refuse-
denved fuel-fired, MOD = modular, SA = starved air, EA = excess air.
bUN » uncontrolled, .SO = spray dryer, FF = fabric filter, ESP = electrostatic preciprtator,
DSI = dry sorbent injection.
cbd = below detection limit.
B-9
-------
TABLE B-3. SUMMARY OF SEWAGE SLUDGE INCINERATOR EMISSION DATA
1 Incinerator type3
FB "
1 FB
i FB
1 FB
I FB
8 MH
8 MH
8 MH
I MH
R MH
0 MH
I MH
U MH
1 " MH
MH
MH
MH
MH
MH
MH
MH
I MH
MH
1 MH
1 '• MH
Control status15
IS
VS/IS
VS/IS
VS/IS
VS/IS
UN
UN
UN
UN
VS
VS
IS
IS
VS/IS
VS/IS
VS/IS
VS/IS
VS/IS/AB
CY
CY
CY
CY/VS
CY/VS/IS
ESP
FF
Emission factor
g/Mg dry sludge
0.15
0.55
1.4
0.27
0.0035
49
0.0010
5.3
51
0.17
0.65
1.5
•1.2
1.9
7.8
2.7
0.32
2.1
32
0.86
4.4
25
8.1
0.17
0.014
1 0"3 Ib/ton dry sludge
0.30
1.1
2.9
0.55
0.0070
98
0.0020
11
100
0.35
1.8
3.0
2.4
3.8
16
.. 5.4
0.64
4.2
65
1.7
8.8
50
16
0.35
0.027
aMH «• multiple hearth, FB - fluidized-bed.
bIS - impingement scrubber, VS - venturi scrubber,
ESP - electrostatic precipitator, FF - fabric filter.
UN
uncontrolled, AB - afterburner, CY - cydone.
B-10
-------
TABLE B-4. SUMMARY OF MEDICAL WASTE INCINERATOR EMISSION DATA
St. Bernadines
0.619
0.552-0.703
1.24
1.10-1.41
Sutler (1988)
Suttar(1987)
M
M
UN
UN
3
3
1.05
1.12
0.420-1.86
0.118-2.44
2.11
0.840-3.71
0.237-4.88
Stanford
St. Agnes
M
M
UN
VS
3
3
1.01
0.751
0.475-1.47
0.558-0.926
2.02
1.50
M
UN
1.59
1.24-2.04
3.19
0.949-2.93
1.12-1.85
2.48-4.09
Cadars Sinai
UN
FF
2.22
< 0.00258
1.45-3.40
< 0.00245-
<0.00265
4.44
<0.00516
2.90-6.80
< 0.00490-
<0.00531
Nazarath
VS/PB
1.48
0.714-2.24
.96
1.43-4.49
Kaiser
M
WS
2.57
1.06-5.31
5.13
2.12-10.6
use
M
UN
2.60
0.921-3.69
1.84-7.38
Borgoss
University of
Michigan
L'enoir
Cape Fear
Q500
RB
G100
M
M
M
UN
DI/FF
DI/FF+ Cd
DI/FF + Ca
UN
DI/FF
UN
UN
VS/PB
UN
UN
14
9
2
3
10
9
3
3
4.39
0.0101
0.0152
0.0723
1.63
0.0131
1.56
4.32
2.69
3.04
5.68
1.27-21.9
0.00615-0.0147
0.0150-0.0154
0.00642-0.195
0.722-2.52
0.00959-O.0156
0.792-2.33
3.26-5.86
2.11-3.81
1.05-6.78
3.90-6.74
8.77
0.0203
0.0303
0.145
3.26
0.0261
3.12
8.65
5.38
6.07
11.4
2.54-43.9
0.0123-
0.0294
0.0299-
0.0307
0.0128-
0.391
1.44-5.03
0.0192-
0.0313
1.58-4.66
6.53-11.7
4.22-7.63
2.10-13.6
7.81-13.5
B-ll
-------
TABLE B-4. (continued}
Facility
AMI Genual
Carolina
Morriatown
Waste
tvpaa
• M
P
M
Control
status13
UN
UN
UN
SD/FF
SD/FF + C
No. of
run*
3
6
6
3
3
Emission factor
g/Mg of waste
Average
0.461
0.302
6.36
0.0213
0.0121
Range
0.4O3-O.575 -'
<0.000-4.67
4.72-8.25
0.0104-0.0293
0.009S5-0.014S
10~3 Ib/ton of waste
0.923
1.30
13.7
0.0427
0.0242
< 0.807-
1.15
< 0.000-
9.34
9.43-16.5
0.0203-
0.0587
0.0191-
aM - mixed medical waete, NA =- not available, G500 - mixed waste from SCO-bed hospital, RB = red bag waste
G10O m mixed waate from 100-bed hospital, P =. pathological waste.
VS - venturi scrubber, PB = packed bed, DSl > duct sorbent injection, ESP - aiectrostatic precipitator
UN . uncontrolled, FF ~ fabric filter, WS - wet scrubber, 01 - dry injection, C - carbon addition, SO '= spray dryer
^Sampling method suspect, results biased low.
"Carbon injection at 1 Ib/hr rate. i
°Carbon injection at 2.5 Ib/hr rate. I
B-12
-------
APPENDIX C
PLANT LOCATIONS AND ANNUAL CAPACITIES
MISCELLANEOUS EMISSIONS SOURCES
FOR
-------
-------
TABLE C-1. COMPANIES USING ELECTRIC ARC FURNACES IN IRON AND STEEL PRODUCTION3
Company /location
Allegheny Ludlum Corp.
Brakenridge Works, Brackenridge, PA
Special Materials Div., Lockport, NY
AL Tech Specialty Steel
Waterviet Plant, Watervert. NY
Arkansas Steel Associates
Newport AR
Armco, Inc.
Baltimore Specialty Steel Corp., Baltimore, MD
Butler Works, Butler, PA
Kansas City Works, Kansas City, MO
Northern Automatic Electric Foundry, (NAEF),
Ishpeming, Ml
Atlantic Steel
Cartersville Works, Cartersville, GA
Auburn Steel
Auburn, NY
Bayou Steel
LaPlace, LA
II Bethlehem Steel
Bethlehem Rant, Bethlehem, PA
Johnstown Rant, Johnstown, PA
Steelton Rant, Steelton, PA
Birmingham Steel
Illinois Steel Div., Birmingham, AL
Mississippi Steel Div., Jackson, MS
Salmon Bay Street, Kent, WA"
Southern United Steel Div., Birmingham, AL
Border Steel Mills
B Paso, TX
Braeburn Alloy Steel
Div., of CCX, Inc., Lower Burrell, PA
Calumet Steel
Chicago Heights, IL
Carpenter Technology
Reading Rant, Reading, PA
1 Cascade Steel Pulling Mills
McMinville, OR
======
2
2
3
2
1
1
1
3 total
(No.2, 3, and 4)
No.5 (1)
No.6 (1)
1 (melting)
1 (holding)
1
1
2
1
1
1
3
2
1
1
2
1
1
1
2
2
A
B
C
D
E
F
2
1 ~
r^^rr^=z::^^^^^__
18
17
12
.. ,»
12
12.5
15
22 ea
22
22
9
9
16 |
18 _J
15
18
18
22
24
18
14
12.5
15
12
11
12.5
11
11
11
11
11
13.5
12-
"~" 19 (egg shaped) ||
C-1
-------
TABLE C-1. (continued)
|| Company/location
1 CF&I Steel
I Pueblo, CO
Champion Steel
I Orwell, OH
I] Chaparral Steel
I Midlothian, TX ' .
1 Charter Sectric Melting
I Chicago, IL
I Citisteel USA, Inc.
I Claymont, DE
| CMC Steel Group
SMI Steel, Inc., Birmingham, AL
SMUI-Texas, Seguin. TX
1 Columbia Tool Steel
H Chicago Heights, IL
H Copperweld Steel
H Warren, OH
I Crucible Materials Corp.
I] Crucible Specialty Metals
Div., Syracuse, NY
1 Cydops Corp.
Bridgeville Works, Bridgeville, PA
Empire-Detroit Steel Div., Mansfield, OH
Eastern Stainless Steel
Baltimore Works, Baltimore, MD
] Edgerwater Steel, Oakmont,
PA
Bectralloy Corp.
Oil City, PA
1 Blwood Uddehoim Steel
New Castle, PA
1 A. Finkl & Sons
Chicago, IL
No. of furnaces
1
1
-1. .
1
1
1
• 1
2
1
1
NO. e
No. 6
No. 8
No. 9
1
1
D
C
G
No. 8
No. 9
1
1
1
1
1
1
1
Shell diameter, ft.
22
22
8.5
19
13.5
22
14
18
11
18
18
18
18 I
15
n's I
12
12
15
20
16
17
15
12.5
13.5
Oval/1 5x1 7
15
C-2
-------
TABLE C-1. (continued)
Company/location
Florida Steel
Charlotte Mill, Charlotte, NC
Jacksonville Mill, Baldwin, FL
Knoxville Div., Knoxville, TN
Tampa Mill, Tampa, FL
Tennessee Mill, Jackson, TN
National Forge
Irvine Forge Div., Irvine, PA
New Jersey Steel
Sayreviile, NJ
North Star Steel
Milton Rant, Milton, PAC
Monroe Plant. Monroe, Ml
St. Paul, Div., St. Paul, MN
Texas Div., Beaumont, TX
Wilton Plan, Wilton, IA
Youngstown Div., Youngstown,
Northwestern Steel and Wire
Sterling Works, Sterling, 1L
NS Group, Inc.
OH-
Kentucky Bectric Steel Corp., Ashland, KY
Koppel Steel Corp., Koppei, PA
%
Newport Steel Corp., Wilder, KY
Nucor Corp.
Crawfordsviile, IN
Darlington Mill, Darlington, SC
Jewell Mill, Jewell, TX
•V
Norfolk Mill, Norfolk, NE
Plymouth Mill, Plymouth, UT
Nucor- Yamato Steel Company
Nucor-Yamato Works, Blytnevilie.
AR
No. of furnaces
•j
1
1
-1.
1
. 1
1
1
3
1
2
2
1
2
1
1
1
2
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
i
1
1
1
1
1
1
1
1
, 1
1
2
2
1 7
I /
10
1 O
12
12.5
17
20 .
15
19
1 ")
9
la
1R
I O
79
*.fi.
ICC
1 O.9
18
38 -
32 ' • j
38
15
20
20
20
18
16
19
19
19
19
22
12.5
12.5
12.5
14
14
1*5 C
13.5
13.5
13.5
13.5
13.5
13.5 -
13.5
13.5
13.5
12.5
15
15
24
C-3
-------
TABLE C-1. (continued)
§ Company/location
1 Ocean State Steel, Inc.
I) E. Providence, Rl
| Oregon Steel Mills, Inc.
a Oregon Steel Mills, Portland, OR
| Georgetown Steel
| Georgetown, Sc
1 Hawaiian Western Steel
1 Ewa, HI
|j Haynes International
| Kokomo Works, Kokomo, IN
1 Inco Alloys International, Inc.
! Hurrtington Works, Huntington, WV
1 Inland Steel Bar Company
Indiana Harbor Works, East Chicaao, IN
1 1RI International
| Specialty Steel Div., Pampa, TX
| Jessop Steel
1 Athlone Industries, Inc., Washington, PA
I J&L Specialty Steel Products
| Midland Plant, Midland, PA
I Jorgensen Forge
Seattle, WA
Keystone Consolidated Industries
Keystone Steel and Wire Div., Peoria, IL
Latiede Steel
Alton, IL
Latrobe Steel
Latrobe, PA
j Lone Star Steel
Texas Specialty Flatroll, Inc., Lone Star, TX
I LTV Steel
Cleveland Works, Cleveland, OH
Lukens Steel
Coatsville, PA
MacSteel
Jackson, Ml
1 Ft. Smith, AR
No. of furnaces
2
-.1
2EF
2LF
1
1
1
2
2
1
1
1
1
4
2
2
1
1
2
A
B
2
2
1
1
2
2
Shell diameter, ft. ||
114
(1,366")
18 I
18.5 .
1J '
9
VI I
14
1J J
11
12
1J 1
24 I
2£ I
22
24 I
12
13.5
16 1
22
14
15 |
C-4
-------
TABLE C-1. (continued)
Company/location
Marathon LeTourneau
Longview Div., Long view, TX
Marion Steel
Marion, OH
McLouth Steel Products
Trenton Works, Trenton. Ml
Owen Bectric Steel Company of South Carolina, Columbia,
SG
Raritan River Steel
Perth Amboy, NH
II Republic Engineered Steel, Inc.,
No. 4 Melt Shop, Cariton, OH
No. 3 Melt Shop, Cariton, OH
|| Roanoke Bectric Steel
Roanoke, VA
|| Rouge Steel
Rouge Works, Dearborn, Ml
Seattle Steel lnc.b
Seattle, WA
Sharon Steel
Steel Div., Farrell, PA
Sheffield Steel
Sand Springs, OK
Slater Steels
Ft. Wayne Specialty Alloy Div.,
Ft. Wayne, IN
Standard Steel
Bumham Plant, Bumham, PA
Latrobe, PA
I Steel of West Virginia
Huntingdon, WV
Tamco
Etiwanda, CA
Teledyne Vasco
Latrobe Plant, Latrobe, PA
Thomas Steel
Lemortt Works, Lemont, IL
D
E
A
B
2
1
1
1
1
3
1
1
2
2
2
2ea
1
1
1
1
1
1
3
1
1
2
_ 1
: 13
13
13.5
•13.5.
24.5
10
11
12
20
• 26
20
-.. u-- j
18
«
-
20.
" "
11
12
14
15
17
13
15 ea
20
- 10
13'5"
C-5
-------
TABLE C-1. (continued)
Company/location
Timken Company Steel Business
Ham'son Plant, Canton, OH
Faircrest Mill, Canton, OH
Union Bectric Steel
Hamon Creek Rant, 'Burgettstown, PA
USS Div. of USX Corp.
South Works, Chicago, IL
Washington Steel
Frtch Works, Houston, PA
No. of furnaces
1
1
1 :
"1
1
1
2.
1d
2
1
1
Shell diameter, ft.
-
22
20
22
77
24
-'
14
24
20
14,16
14
aSource: Huskonen, W. W. Adding the Final Touches. 33 Metal Producing. 29:28-131. May 1991.
bBirmingham Steel is proceeding with a plan to close the Salmon Bay Steel melt shop and will merge the
operation wrth the Seattle Steel, Inc., facilities it is acquiring.
cPresentiy idle.
dOn standby.
C-6
-------
TABLE C-2. PORTLAND CEMENT PRODUCTION FACILITIES3
Clinker capacity.
Company and location
No./type of kiln
Alamo Cement Co.
San Antonio, TX
Allentown Cement Co., Inc.
Blandon, PA
Armstrong Cement & Sup. Co
Cabot, PA
Ash Grove Cement Co
Nephi, UT
1 Louisville, NE
Durkee, OR
Foreman, AR
Montana City, MT
Chanute, KS
Inkom, 10
Blue Circle, Inc.
Ravena, NY
Atlanta, GA
Tulsa, OK
Calera, AL
Boxcrow Cement
Midlothian, TX
Calaveras Cement Co.
Redding, CA
Tehachapi, CA
California Portland Cement
Mojave, CA
Coiton, CA
Rillito, AZ
Capitol Cement Corporation
Martinsburg, WV
Capitol Aggregates, Inc.
San Antonio, TX
Carlow Group
Zanesville, OH
Centex
Laramie, WY
La Sails, IL
Fernley, NV
Continental Cement Co., Inc.
Hannibal, MO
Dixon-Marquette
Dixon, IL
Dragon Products Company
Thomaston, ME
2-Dry
1-Dry
3-Wet
1-Wet
2-Wet
2-Wet
2-Wet
2-Dry
2-Dry
2-Dry
1-Drv
1-Dry
1-Wet
1-Dry
2-Dry
4-Dry
3-Wet
1 -Dry/1 -Wet
2-Wet
1-Dry
1-Dry
2-Dry
1-Wet
4-Dry
1-Wet
872
454
857
254
450
191
1,390
555
544
544
907
591
386
943
680
966
746
456/319
547
418
372
376
544
475
413
ouu
961
500
945
280
496
210
1,532
612
600
600
1 ,000
651
1,039
750
1,065
I
822
503/352 1
603
461
as 1
600 1
524
455
C-7
-------
TABLE C-2. (continued)
Company and location
Essroc Materials
Nazareth, PA
Speed, IN
Bessemer, PA
Frederick, MD
ILogansport, IN
Florida Crushed Stone
Brooksville, FL
Giant Cement Company
Harteyville, SC
Gifford-Hill & Co.. Inc.
Harteyville, SC
Oro Grande, CA
Riverside, CA
Glens Falls Cement Co.
1 Glens Falls, NY
I Hawaiian Cement Company
I Ewa Beach, HI
I Heartiand Cement Company
1 Independence, KS
I Hercules Cement Company
1 Stockertown, PA
H Holnam, Inc.
Theodore, AL
1 Clarksville, MO
I Holly Hilt, SC
Mason City, IA
Florence, CO
Fort Collins, CO
Dundee, Ml
Artesia, MS
Seattle, WA
Three Forks, MT
Ada, OK
Tijeras, NM
Saratoga, AR
I Morgan, UT
j Independent Cement Corp.
Catskill, NY
Hagerstown, MD
] Kaiser Cement Corp.
Permanente, CA
Keystone Cement Company
Bath, PA
Kosmos Cement Co.
Louisville, KY
! Pittsburgh. PA
No./type of kiln
1-Dry
2-Dry
1 -Dry/1 -Wet
2-Wet
2-Wet
1 -Dry
4- Wet
1 - Dry
7 -Dry
2 - Dry
1-Orv
1-Dry
4-Ory
3-Dry
1-Ory
1-Wet
2-Wet
2-Dry
3-Wet
1-Dry
2-Wet
1-Wet
1-Wet
1-Wet
2-Wct
2-Dry
2-Wet
2-Wet
1-Wet
1-Dry
1-Dry
2-Wet
1-Ory
- 1-Wet
Clinker capacity,3
103 Mg/year
874
863
295/191
336
367
518
789
-
560
1 ,041
100
450
239
305
656
1,308
1,190
991
806
780
448
380
457
429
283
544
448
335
298
464
452
1 ,452
J546
«S7
2I57
963
951
325/21 1
370
404
571
870
617
1,148
T10
495
263
336
723
1,442
1,312
1,092
888
860
494
970
504
473
312
600
494
369
328
512
498
1,600
602
724
394
C-8
-------
TABLE C-2. (continued)
Company and location
LaFarge Corporation
New Braunfels, TX
Buffalo, IA
Demopolis, AL
Grand Chain, IL
Alphena, Ml
Whitehall, PA
Sugar Creek, MO
Paulding, OH
Fredonia, KS
Lehigh Portland Cement
Mason City, IA
Leeds, AL
Cementon, NY
Union Bridge, MD
Mitchell, IN
York, PA
Waco. TX
Lone Star Industries
Cape Girardeau, MO
Greencastie, IN
Oglesby, IL
Pryor, OK
Nazareth, PA
Sweetwater, TX
Medusa Cement Co.
Charlevoix, Ml
Clinch-field, GA
Wampum, PA
Mitsubishi Cement Corp.
Lucerne Valley, CA
Monarch Cement Company
Humboldt, KS
Des Moines, IA
National Cement Company
Ragland, AL
Nat!. Cement Co. of California
Lebec, CA
II North Texas Cement
Midlothian, TX
Phoenix Cement Company
Clarkdale, AZ
II Rinker Portland Cement Corp.
I Miami, FL
River Cement Company
Festus, MO
RMC Lonestar
Davenport, CA
No./type of kiln
1-Dry
1-Dry
1-Dry
2-Dry
5-Dry
3-Dry
2-Dry
2-Wet.
2-Wet •
1-Dry
1-Dry
1-Wet
4-Dry
3-Dry
1-Wet
1-Wet
1-Dry
1-Wet
1-Dry
3-Dry
4-Dry
3-Dry
'1-Dry
1 -Dry/1 -Wet
3-Dry
1-Dry
3-Dry
2-Wet
1-Dry
1-Ory
3-Wet
3-Dry
2-Wet
2-Drv
1-Orv
Clinker capacity,3 1
10** Mg/year
865
778
655
1,076
1,773
689
437
445
347
689
591
506
900
689
90
73
1,002
649
422
623
565
449
1,237
508/187
638
1,514
611
272
767
590
816
640
512
1,070
726
103tonS/vear I
JLJLH
954
858
.722
1,186
1,954
760
482
490
382
760
651
558
992
760
99
81
1,104 fl
715 H
465
687
623
495
1 ,364
560/206
703
. 1,669
674
300
845
650
900
705
564
1,179
800
C-9
-------
TABLE C-2. (continued)
Company and location
Roanoke Cement Company
Ctoverdale. VA
Signal Mountain Cement Co.
Chattanooga, TN
South Dakota Cement
Rapid City. SD
Southdown, Inc.
Victorville, VA
Brooksville, FL
Knoxville, TN
Fairbom, OH
Lyons, CO
Odessa, TX
St. Mary's Peerless Cement Co.
Detroit, Ml
Tarmac Florida, Inc.
Medley, FL
Texas Industries
New Braunfels, TX
Midlothian, TX
Texas-Lehigh Cement Co.
Buda. TX
Total capacity reported
No./type of kiln
5-Dry
2-Wet
1 -Dry/2-Wet
2-Dry
2-Dry
1-Dry
1-Dry
1-Dry
2-Dry
1-Wet
3-Wet
1-Dry
4-Wet .
1-Dry
135-Ory/79-Wet
Clinker caoacitv.3
103 Mg/year
1,013
408
408/287
1,406
11,089
544
553
408
499
533
933
689
1,139
895
73,532
1 03 tons/year
1,117
450
450/316
1,550
1,200
600
610
450
550
610
1,028
759
1,256
987
Source: Portland Cement Association. U.S. and Canadian Portland Cement
Summary. Portland Cement Association. Skokie, IL. 1990.
aNote:
Kilns reported as inactive in 1990
Industry: Plant Information
. Clinker capacity
1pj*kg/year10J tons/year
Ash Grove Cement
California Portland Cement
Holnam, Inc.
Lone Star Industries
Medusa Cement Company
Monarch Cement Company
Tarmac Florida
Total active capacity
Foreman, AR 1 kiln
Rillito, AZ 2 kilns
Florence, CO 2 kilns
Sweetwater, TX 1 kiln
Clinchfield, GA 1 kiln
Des Moines, IA 2 kilns
Medby, FL 2 kilns
246
245
334
150
187
272
334
71,764
271
270
368
165
206
300
368
79,108
C-10
-------
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-------
TABLE C-4. PHOSPHATE ROCK PRODUCERS3
I
| Company and location
I Cargill, Inc. (Gardinier Inc., subsidiary)
Fort Meade, FI
| Fort Green, FL
I C & G Holdings {Estech, Inc., subsidiary)
1 Fort Meade, FL
I Chevron Fertilizer Division (Chevron Chemical Co., subsidiary)
1 Vernal, UT
j Cominco Fertilizers (Cominco American, Inc.)
J Garrison, MT
] Freeport-McMoRan Resource Partners (Agrico Chemical Co.)
Fort Green, FL
Payne Creek Mine, FL
Lilian, FL
IMC Fertilizer Group, Inc.
Clear Springs, FL
1 Haynsworth Bradley, FL
Annual capacity,
103 metric tons (Mg)
2,000
1,500
900
1 ,000
300
4,000
2,300
550
.
1,600
2,800
Kingsford, FL
Lonesome Bradley, FL
Noralyn, FL
4,500
2,200
4,500
Four Corners Mine (IMC Fertilizer Group, Inc., subsidiary)
Four Comers, FL
Mobile Mining & Minerals Co., (Mobile Oil Corporation)
Big Four, FL
Nichols, FL
5,000
1,800
1,300
I Monsanto Chemical Company (Monsanto Company)
Soda Springs, ID
900
I Nu-West Industries, Inc.
Conda, ID
2,000
J Occidental Chemical Corporation (Occidental Petroleum
I Corporation)
White Springs (Suwannee River), FL
White Springs (Swift Creek), FL
Columbia, TN -
2,500
2,000
500
I Rhone-Poulenc Basic Chemicals Co. (Rhone-Poulenc Inc.)
Mount Pleasant, TN
Wooley Valley, ID
300
500
I Royster Company (Nu-Gulf Industries)
Myakka City, FL
1,700
t'J.R. Simplot Co.
Afton, WY
Gay, ID
Texasgulf, Inc.
2,000
2,000
Aurora, NC
6,000
C-12
-------
TABLE C-4. (continued)
Company and location
Annual capacity,
103 metric tons (Mg)
rosco Corporation (S.eminoie Fertilizer Corp. subsidiary)
Bartow, FL
2,400
TOTAL
59,050
Source: SRI International. 1991 Directory of Chemical Producers: United States of America SRI
International, Menlo Park, CA. 1991.
aAs of January 1, 1991.
C-13
-------
TABLE C-5. ELEMENTAL PHOSPHORUS PRODUCERS
Company/location3
FMC Corporation
Pocatelio, ID
Monsanto Company
Soda Springs, ID
Rhone-Poulenc, Inc.
Silver Bow, MN
TOTAL
1 " '"'^1 1 ' 1 T
Annual capacity, 1 03 Mg ( ! 0^ tons)
124 (137)
104(115)
38(42)
267 (294)
Sources: Van Wazer. J. R. Phosphorus and the Phosphides. (In) Kirk-Othmer Concise Encyclopedia
of Chemical Technology. M. Grayson and D. Eckroth, eds. A Wiley-lnterscience
Publication, John Wiley and Sons, New York, NY. 1985.
i
Stowasser, W. P. Phosphate Rock. Annual Report: 1991. Bureau of Mines, U.S
Department of the Interior. Washington, DC. November 1992.
Reflects most recent plant closings reported in Stowasser, W.F. Phosphate Rock. Annual
Report: 1991 Bureau of Mines, U.S. Department of the Interior,, U.S. Department of the Interior. '
Washington, DC. November 1992.
CV14
-------
1. REPORT NO.
EPA-454/R-93-040
. TITLE AND SUBTITLE
REPORT DATA
the reverse ," '
3. RECIPIENT'S ACCESSION NO.
Locating and Estimating Air .Emissions From
Sources of Cadmium and Cadmium Compounds
5. REPORT DATE
September 1993
6. PERFORMING ORGANIZATION COO6
7. AUTHOR(S)
Ms. Robin Jones, Dr. Tom Lapp/
and Dr. Dennis Wallace
. PERFORMING ORGANIZATION REPORT
NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Midwest Research Institute
401 Harrison Oaks Boulevard, Suite 350
Gary, North Carolina 27513
12. SPONSORING AGENCY NAME AND ADDRESS*
Technical Support Division
OAR, OAQPS, TSD, EFMS (MD-14)
Emission Inventory Branch
Research.Triangle Park, North Carolina 27711
11. CONTRACT/GRANT NO.
68-D2-0159
IS. SUPPLEMENTARY NOTES
EPA Project Officer:
Anne A. Pope
- TYE'°F
ax
tE-'°
r
AND PERIOD COVERED
1*. SPONSORING AGENCY CODE
116. ABSTRACT
and
SSJSS
lions'
compounds
Its intended audience includes deralste
5erS°nnel *nd ^hers interested f in locating
of ai?
This document presents information on (1) the types o-f sources that
rMe^n^thaf ^^^ COmfOUndS' (2) pr^ess ^ SSSS. and
™?? Si P • .that may be emitted within these sources, and (3)
available emissions information indicating the potential for cadmium
and cadmium compound releases into the air f ron? eacS !^ operation
^^^^•••^••^^^.^a
KEY WORDS AND DOCUMENT ANALYSIS
Cadmium
Cadmium Compounds
Air Emissions Sources
Locating Air Emissions Sources
Toxic Substances
18. DISTRIBUTION STATEMENT
Unlimited
EPA
b.IDENTIFIERS/OPEN ENDED TERMS |c. COSATI Field/Group
19. S6CUR»TY-CLASS-Y77ttr.R,.po«-rr
Unclassified
2O. SECURITY CLASS (Tliii pagei
Unclassified
P««V«OU« COITION <* OUOUCT
21. NO. OF PAGES
318
22. PRICE
-------
------- |