DCN No. 85-203-012-23-06
Radian No. 203-012-23
EPA No. 68-02-3818
Assignment No. 23
BACKGROUND INFORMATION DOCUMENT
FOR CADMIUM EMISSION SOURCES
FINAL REPORT
Prepared for:
Rayburn M. Morrison
Technical Project Officer
Pollutant Assessment Branch
U. S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Prepared by:
Radian Corporation
3200 Progress Center
P. 0. Box 13000
Research Triangle Park, North Carolina 27709
May 1985
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DISCLAIMER
This report has been reviewed by the Strategies and Air Standards
Division (SASD). U. S. Environmental Protection Agency (EPA) to approve its
contents for publication. Approval for publication does not signify that
the contents necessarily reflect the views and policies of the U. S.
Environmental Protection Agency. nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
ii
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EXECUTIVE SUMMARY
Under Section 122 of the Clean Air Act (CAA). the U. S. Environmental
Protection Agency (EPA) is required to investigate whether cadmium emissions
into ambient air cause or contribute to air pollution which may reasonably
be expected to endanger public health. If such an investigation yields a
positive determination that cadmium emissions from some sources may cause or
contribute to an endangerment of public health. then EPA must determine
whether cadmium should be regulated under Section 108. 111. or 112 of' the
CAA. This document summarizes the results of an ongoing EPA effort to study
cadmium air emission sources as required under Section 122. The conclusiOns
reached by EPA following an analysis of the results reported in this docu-
ment. the cadmium health assessment document. and a cadmium exposure and
risk assessment will dictate whether or not cadmium is to be regulated under
Section 108. 111. or 112 of the CAA. If listed under Section 112. EPA may
have to develop national emission standards for hazardous air pollutants
(NESHAP's) for some or all of the cadmium emissions source categories.
This document specifically addresses six cadmium emission source
categories that have been determined to represent the most significant
potential sources of risk to the public from cadmium. These six source
categories of significance were identified from previous source assessment
and preliminary exposure/risk work conducted over the last 18 months on a
total of 14 cadmium emission source categories. Rationales for the
selection of the six major categories are provided in Appendix A of this
report. The cadmium source categories addressed in detail in this repprt
are primary cadmium smelters. primary lead smelters, primary zinc/zinc oxide
smelters. municipal waste incinerators. sewage sludge incinerators. and
cadmium pigments manufacturers. The following types of information are
presented in the document for each of the six source categories.
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a brief description of the basic source category processes,
including flow sheets;
a description of cadmium emission points within processes,
including a delineation of the nature of emissions as process or
fugitive and as particulates, aerosols, or vapors;
I
a determination of the chemical form of cadmium emissions;
names and locations of known facilities;
a description of existing cadmium controls;
an estimate of current cadmium emissions;
a discussion of current regulations impacting cadmium control;
a description of control options that may represent estimated best
control (EBC) for each cadmium emission point;
an estimate of cadmium emissions under the scenario that EBC is in
place.
The primary cadmium smelting source category consists of five plants,
one dedicated cadmium smelter, and the other four co-product cadmium
smelters which are co-located at primary zinc smelters. The cadmium
smelting process contains point and fugitive cadmium emission sources. The
majority of point sources are well controlled by the use of baghouses.
Fugitive cadmium emission sources are generally poorly characterized and
emissions are not quantifiable with currently existing data. Total cadmium
emissions for the source category are estimated at 8.2 Mg (9.1 tons)/yr,
exclusive of fugitive source cadmium emissions.
The primary lead smelting source category consists of five plants which
have an estimated combined cadmium emissions total of 26.5 Mg
(30.4 tons)/yr. Of this total 19 Mg (21.8 tons) are attributable to point
sources, while 7.5 Mg (8.6 tons) are emitted by fugitive sources. All point
or process cadmium emission sources at lead smelters are co~trolled with the
estimated best control (EBC) systems for this industry, which consist of
baghouses and contact sulfuric acid plants and their associated gas
pre-cleaning equipment. Most fugitive cadmium emission sources are
controlled with EBC currently; however, all fugitive sources should be at
iv
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EBC within the next 2 years due to the regulatory impacts of the State
Implementation Plans (SIP's) for lead and Occupational Safety and Health
Administration (OSHA) tripartite agreements.
The primary zinc smelting source category also consists of five plants,
four of which produce zinc electrolytically and one which produces zinc
electro thermally. The electrolytic zinc plants only have one process source
of cadmium emissions, that being the ore roaster. All plants use the EBC of
a contact sulfuric acid plant and its associated gas pre-cleaning equipment
to control roaster cadmium emissions. Cadmium fugitive emissions from
electrolytic plants come primarily from ore storage and associated handling
and transfer operations. Estimated best control is not currently used on
fugitive emission sources at electrolytic zinc plants. Total cadmium
emissions from electrolytic zinc plants are estimated to be 0.2 Mg
(0.22 tons)/yr.
The single electrothermal zinc plant is estimated to have total cadmium
emissions of 3.2 Mg (3.5 tons)/yr. The majority of this emissions total is
attributable to process and not fugitive. emission sources.' E~timated best
control consisting of baghouses, acid plants and associated gas pre-cleaning
equipment, and scrubbers is employed on process emission sources. A small
number of fugitive emission sources do not currently have EBC in place.
Three American Process zinc oxide facilities are currently in operation
and are emitting an estimated 2.4 Mg (2.6 tons)/yrof cadmium. This
estimated cadmium emissions total is all attributable to process sources at
the zinc oxide plants. Estimated best control is currently practiced on all
process sources. No data exists from which to reasonably estimate fugitive
cadmium emissions from zinc oxide plants. Several fugitive emission sources
are known not to be using EBC.
The municipal waste incineration source category consists of
conventional and modular waste incinerators. Currently, 57 conventional
municipal waste incinerators are in operation in the U. S., primarily in the
States of Connecticut, New York, Pennsylvania, Massachusetts, Florida, Ohio,
and Virginia.
Roughly 50 percent of these sources are equipped with
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a brief description of the basic source category processes,
including flow sheets;
a description of cadmium emission points within processes,
including a delineation of the nature of emissions as process or
fugitive and as particulates, aerosols, or vapors;
1
a determination of the chemical form of cadmium emissions;
names and locations of known facilities;
a description of existing cadmium controls;
an estimate of current cadmium emissions;
a discussion of current regulations impacting cadmium control;
a description of control options that may represent estimated best
control (EBC) for each cadmium emission point;
an estimate of cadmium emissions under the scenario that EBC is in
place.
The primary cadmium smelting source category consists of five plants,
one dedicated cadmium smelter, and the other four co-product cadmium
smelters which are co-located at primary zinc smelters. The cadmium
smelting process contains point and fugitive cadmium emission sources. The
majority of point sources are well controlled by the use of baghouses.
Fugitive cadmium emission sources are generally poorly characterized and
emissions are not quantifiable with currently existing data. Total cadmium
emissions for the source category are estimated at 8.2 Mg (9.1 tons)/yr,
exclusive of fugitive source cadmium emissions.
The primary lead smelting source category consists of five plants which
have an estimated combined cadmium emissions total of 26.5 Mg
(30.4 tons)/yr. Of this total 19 Mg (21.8 tons) are attributable to point
sources, while 7.5 Mg (8.6 tons) are emitted by fugitive sources. All point
or process cadmium emission sources at lead smelters are co~trolled with the
estimated best control (EBC) systems for this industry, which consis~ of
baghouses and contact sulfuric acid plants and their associated gas
pre-cleaning equipment. Most fugitive cadmium emission sources are
controlled with EBC currently; however, all fugitive sources should be at
iv
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EBC within the next 2 years due to the regulatory impacts of the State
Implementation Plans (SIP's) for lead and Occupational Safety and Health
Administration (OSHA) tripartite agreements.
The primary zinc smelting source category also consists of five plants,
four of which produce zinc electrolytically and one which produces zinc
electro thermally. The electrolytic zinc plants only have one process source
of cadmium emissions, that being the ore roaster. All plants use the EBC of
a contact sulfuric acid plant and its associated gas pre-cleaning equipment
to control roaster cadmium emissions. Cadmium fugitive emissions from
electrolytic plants come primarily from ore storage and associated handling
and transfer operations. Estimated best control is not currently used on
fugitive emission sources at electrolytic zinc plants. Total cadmium
emissions from electrolytic zinc plants are estimated to be 0.2 Mg
(0.22 tons)/yr.
The single electrothermal zinc plant is estimated to have total cadmium
emissions of 3.2 Mg (3.5 tons)/yr. The majority of this emissions total is
attributable to process and not fugitive. emission sources. Estimated best
. .
control consisting of baghouses, acid plants and associated gas pre-cleaning
equipment, and scrubbers is employed on process emission sources. A small
number of fugitive emission sources do not currently have EBC in place.
Three American Process zinc oxide facilities are currently in operation
and are emitting an estimated 2.4 Mg (2.6 tons)/yr.of cadmium. This
estimated cadmium emissions total is all attributable to process sources at
the zinc oxide plants. Estimated best control is currently practiced on all
process sources. No data exists from which to reasonably estimate fugitive
cadmium emissions from zinc oxide plants. Several fugitive emission sources
are known not to be using EBC.
The municipal waste incineration source category consists of
conventional and modular waste incinerators. Currently, 57 conventional
municipal waste incinerators are in operation in the U. S., primarily in the
States of Connecticut, New York, Pennsylvania, Massachusetts, Florida, Ohio,
and Virginia.
Roughly 50 percent of these sources are equipped with
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electrostatic precipitators (ESP's) which are defined to be EBC. Total
cadmium emissions from conventional waste incinerators are estimated at
77 Mg (85 tons)/yr.
Approximately 125 modular incinerators are estimated
to be in operation
relatively small
No controlled
burning municipal waste at 59 locations. Because of the
size of individual modular units, most are uncontrolled.
facilities were identified during this study, and as such, no EBC system
could reliably be recommended. Total existing cadmium emissions from
modular municipal waste incinerators are about 3 Mg (3.3 tons)/yr. Over
44 percent of the emissions total are estimated to originate from only
15 percent of the installations.
The sewage sludge incineration source category consists of
approximately 300 to 350 incinerators, employing a wide variety of emission
controls which apparently are dependent on the unit installation date.
Incinerators installed after 1978 are predominantly controlled by
venturi/impingement-tray scrubbers, which are defined to be EBC for this
, .
source category. Data are limited on the emission controls applied to
sludge incinerators installed prior to 1978; however, for the small portion
where it is available, venturi/impingement-tray scrubbers do not
predominate. It is anticipated that the majority of the total number of
pre-1978 units do not have EBC in place. Existing cadmium emissions from
all sludge incinerators are estimated to be 10.3 Mg (11.4 tons)/yr.
The cadmium pigments manufacturing source category consists of four
plants with a combined existing cadmium emissions total of 1,343 kg
(2,962 lbs)/yr. Cadmium pigments plants were found to largely have EBC in
place on process and fugitive cadmium emission sources. Depending on the
emission source, EBC for process emissions is either a baghouse or a wet
scrubber. Fugitive cadmium emissions control is primarily achieved by
capturing emissions in a hood, enclosure, or vacuum system and ducti~g the
emissions to a baghouse. Available data indicate that fugitive cadmium
emissions control could be improved at some pigments facilities. Fugitive,
and to some extent process, emissions control is significantly impacted by
the economic value of the cadmium materials and by OSHA limitations on
workplace cadmium concentrations.
vi
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TABLE OF CONTENTS
List of Tables.
. . . . . . . . . . . . . . . . . . . . . . . . . .
List of Figures.
3.0
4.0
Chapter
1.0
2.0
2.6
. . . . . . . . . . . . . . . . . . . . . . . . . .
Background and Introduction
. . . . . . . . . . . . . . . . . .
1.1
1.2
1.3
Background. .
Introduction.
References for
. . . .
. . . . . . .
. . .
. . .
. . . . .
. . . . . . . . .
.....
. . . . . . . .
Chapter 1 . . . .
. . . . .
. . . .
. . . .
Primary Cadmium Smelting. .
...............
2.1
2.2
2.3
2.4
2.5
Source Category Description. . . . . . . . . . . . . . . .
Process Description. . . . . . . . . . . . . . . . . . . .
Existing Cadmium Emission Controls. . . . . . . . . . . .
Existing Emissions. . . . . . . . . . . . . . . . . . . .
Estimated Best Control (EBC) Recommendation. . . . . . . .
2.5.1 Recommended EBC . . . . . . . . . . . . . . . . . .
2.5.2 Prevalence of EBC . . . . . . . . . . . . . . . . .
2.5.3 EBC Emission Levels. . . . . . . . . . . . . . . .
References for Chapter 2 . . . . . . . . . . . . . . . . .
Primary Lead Smelting. . .
3.1
3.2
3.3
3.4
3.5
3.6
. . . . . . . . . . . . . . .
Source Category Description. . . . . . . . . . . . . . . .
Process Description. . . . . . . . . . . . . . . . . . . .
Existing Controls. . . . . . . . . . . . . . . . . . . . .
Existing Emissions. . . . . . . . . . . . . . . . .
Estimated Best Control (EBC) Recommendation. . . . .
3.5.1 Recommended EBC . . . . . . . . . . . . . . . . . .
3.5.2 Prevalence of EBC . . . . . . . . . . . . . .
3.5.3 EBC Emission Levels. . . . . . . . . . . . .
References for Chapter 3 . . . . . . . . . . . . . . . . .
Primary Zinc Smelting. . .
4.1
4.2
. . . . . . . . . . . . . . .
Source Category Description. . . . . . . . . . . . .
Process Description. . .. . . . . . . . . . . .
4.2.1 Electrolytic Zinc Production. . . . . . . . . . . .
4.2.2 Electrothermic Zinc Production. . . . . . . . . . .
vii
Page
x
xii
1
1
3
6
7
7
9
12
15
16
16
17
17
19
20
20
22
28
32
34
34
34
36
37
39
39
41
41
44
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Chapter
5.0
6.0
4.6
5.1
5.2
5.3
5.4
5.5
5.6
TABLE OF CONTENTS (Continued)
4.3
Existing Controls. . . . . . . . . . . . . . . . . .
4.3.1 Controls at Electrolytic Zinc Plants. . . . . . . .
4.3.2 Controls at the Electrothermic Zinc Smelter. . . .
Existing Emissions. . . . . . . . . . . . . . . . . . . .
Estimated Best Control (EBC) Recommendation. . . . . . . .
4 .5 . 1 Re commended EBC . . . . . . . . . . . . . . . . . .
4.5.2 Prevalence of EBC . . . . . . . . . . . . . . . . .
4.5.3 EBC Emission Levels. . . . . . . . . . . . . . . .
References for Chapter 4 . . . . . . . . . . . . . .
4.4
4.5
Zinc Oxide Production. . . .
. . .
. . . . . . .
. . . .
Source Category Description. . . . . . . . . . . . . . . .
Process Description. . . . . . . . . . . . . . . . .
Existing Controls. . . . . . . . . . . . . . . . . .
Existing Emissions. . . . . . . . . . . . . . . . . . . .
Estimated Best Control (EBC) Recommendation. . . . . . . .
5.5.1 Recommended EBC . . . . . . . . . . . . . . .
5.5.2 Prevalence of EBC . . . . . . . . . . . . . . . . .
5.5.3 EBC Emission Levels. . . . . . . . . . . . .
References for Chapter 5 . . . . . . . . . . . . . . . . .
Sewage Sludge Incineration. .
6.1
6.2
6.3
6.4
6.5
6.6
6.7
.....
.....
. . . . . . .
Source Category Description. . . . . . . . . . . . . . . .
Process Description. . . . . . . . . . . . . . . . . . . .
6.2.1 Process Overview. . . . . . . . . . . . . . .
6.2.2 Multiple-Hearth Furnaces. . . . . . . . . . . . . .
6.2.3 Fluidized-Bed Incinerators. . . . . . . . . . . . .
6.2.4 Electric Incinerators. . . . . . . . . . . . . . .
6.2.5 Other Incinerator Designs. . . . . . . . . . . . .
6.2.6 Cadmium Emissions Enrichment Behavior. . . . . . .
Existing Controls. . . . . . . . . . . . . . . . . . . . .
6.3.1 Control Technologies Applied Prior to 1978. .
6.3.2 Control Technologies Applied After 1978 . . .
6.3.3 Control Device Performance on Cadmium Emissions. .
Existing Emissions. . . . . . . . . . . . . . . . . . . .
Estimated Best Control (EBC) Recommendation. . . . . . . .
EBC Emissions. . . . . . . . . . . . . . . . . . . . . . .
References for Chapter 6 . . . . . . . . . . . . . .
viii
Page
47
47
50
51
53
53
53
55
56
57
57
59
63
66
67
67
68
68
70
71
71
84
84
84
89
92
93
93
94
95
97
97
100
101
102
104
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Chapter
TABLE OF CONTENTS (Continued)
7.0 Municipal Waste Incineration. . .
......
.....
. . . .
7.1
7.2
7.3
Source Category Description. . . . . . . . . . . . . . . .
Process Description. . . . . . . . . . . . . . . . . . . .
Existing Controls. . . . . . . . . . . . . . . . . . . . .
7.3.1 Conventional Incinerators. . . . . . . . . .
7.3.2 Modular Incinerators. . . . . . . . . . . . . . . .
Existing Emissions. . . . . . . . . . . . . . . . . . . .
7.4.1 Conventional Incinerators. . . . . . . . . . . . .
7.4.2 Modular Incinerators. . . . . . . . . . . . . . . .
Estimated Best Control (EBC) Recommendations. . . . . . .
7.5.1 Conventional Incinerators. . . . . . .
7.5.2 Modular Incinerators. . . . . . . . . . . . . . . .
References for Chapter 7 . . . . . . . . . . . . . . . . .
7.4
7.5
7.6
8.0
Cadmium Pigments Manufacturing. . .
. . . .
8.1
8.2
8.3
8.4
8.5
. . . .
. . .
8.6
Source Category Description. . . . . . . . . . . . . . . .
Cadmium Pigments Manufacturing 'Process Description. . . .
8.2.1 . Process Description. . . . . .'. . . . . . .
8.2.2 Emission Sources. . . . . . . . .
Existing Controls. . . . . . . . . . . . . . . . . . . . .
Existing Emissions. . . . . . . . . . . . . . . . . . . .
Estimated Best Control (EBC) Recommendation. . . . . . . .
8.5.1 Recommended EBC . . . . . . . . . . . . . . .
8.5.2 EBC Emission Levels. . . . . . . . . . . . .
References for Chapter 8 . . . . . . . . . . . . . . . . .
Appendix A - Technical Memos Describing Rationales for Excluded
Source Categories. . . . . . . . . . . . . . . . . . .
ix
Page
106
106
112
123
123
129
130
130
133
133
133
141
146
148
148
152
152
155
158
159
163
163
166
168
169
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Table
2-1
2-2
2-3.
3-1
3-2
3-3
4-1
4-2
4-3
5-1
5-2
5-3
6-1
6-2
6-3
6-4
LIST OF TABLES
I
The Domestic Primary Cadmium Smelters.
. . . . .
. . . . .
Cadmium Emissions Sources and Existing Controls
in the Primary Cadmium Smelting Source Category.
.....
Prevalence of Cadmium EBC in the Primary Cadmium
Smelting Source Category. .. . . . . . . . . .
. . . . .
The Domestic Primary Lead Smelters
. . .
. . .
. . . . . .
Cadmium Emissions Sources and Existing Controls
in the Primary Lead Smelting Source Category. .
. . . . .
Prevalence of Cadmium EBC in the Primary Lead
Smelting Source Category. . . . . . . . . . . . .
. . . .
,The Domestic Primary Zinc Smelters
. . ~ . . . . . . . . .
Cadmium Emissions Sources and Existing Controls
in the Primary Zinc Smelting Source Category.
. . . . . .
Prevalence of Cadmium EBC in the Primary Zinc
Smelting Source Category. . . . .
. . .
The Domestic American Process Zinc Oxide Plants.
. . . . .
Cadmium Emissions Sources and Existing Controls
in the Zinc Oxide Source Category. . . . . . . . . .
Prevalence of Cadmium EBC in the Zinc Oxide
Ca tegory . . . . . . . . . . . . . . . . . . . . . . . . .
Locations of Wastewater Treatment Plants Using
Sewage Sludge Incinerators. . . . . . .
. . . . . .
Distribution of Emission Control Technologies Applied
to Selected Sewage Sludge -Incinerators Prior to 1978 . . .
Distribution of Emission Control Technologies Applied
to Sewage Sludge Incinerators After 1978 . . . . . .
Control Efficiencies for Cadmium Emissions from
Sewage Sludge Incinerators. . . . . . . .
.....
x
Page
8
13
18
21
29
35
40
48
54
58
64
69
74
96
98
99
-------
Table
7-1
7-2
7-3
7-4
7-5
7-6
8-1
LIST 'OF TABLES (Continued)
Conventional Municipal Waste Incineration Facilities
Modular Municipal Waste Incineration Facilities. . . . . .
Estimated Existing Cadmium Emissions from Conventional
Municipal Waste Incinerators. . . . . . . . . . . .
Estimate of Existing Cadmium Emissions from Modular
Municipal Waste Incinerators. . . . . . . . . . . . . . .
Estimate of Cadmium Emissions from Conventional
Incinerators with EBC in Place. . . . . . . . .
.....
Estimate of Cadmium Emissions from Modular Incinerators
with EBC in Place. . . . . . . . . . . . . . . . . . . . .
Existing Cadmium Emissions Estimates for Cadmium
Pigment Plants. . . . . . . . . . ., . . . . . .
. . . . .
xi
Page
108
113
124
134
138
142
162
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Figure
2-1
~-1
4-1
4-2
5-1
5-2
6-1
6-2
6-3
7-1
7-2
7-3
8-1
8-2
LIST OF FIGURES
I
Generic Cadmium Production Flow
Sheet. . . . . . . . . . .
Primary Lead Smelting. . .
. . . . . . . . . . .
. . . .
A Typical Electrolytic Zinc Smelter.
. . .
. . . .
Electrothermic Zinc Smelting at the St. Joe/Monaca,
Pennsylvania Plant. . . . . . . . . . . . . . . . .
. . .
Process Flow Diagram for the ASARCO/Columbus Plant. . . .
The New Jersey Zinc/Palmerton Zinc Oxide Plant.
. . . . .
Location of Currently Operating Sewage Sludge
Incineration Facilities in the Continental
United States. . . . . . . . . . . . . . . .
......
Cross Section of a Typical Multiple-Hearth
Incinerator. . . . . . . . . . . . . . . . . .
. . . . .
Cross Section of a Fluidized-Bed Sewage Sludge
Incinerator. . . . . . . . . . . . . . . . . .
.....
Typical Configurations of Conventional Municipal
Waste Incinerators. . . . . . . . . . . . . . . . . . . .
Typical Configurations of Modular Waste Incinerators. . .
Particle Size Distribution of Total Particulate and
Cadmium Emissions from a Municipal Waste Incinerator. . .
Cadmium Pigments Color Range. . . . . .
. . . .
. . . . .
Process Flowsheet for the Production of Cadmium
Pigments. . . . . . . . . . . . . . . . . . . .
. . . . .
xii
Page
10
23
42
45
60
62
83
85
90
117
119
122
149
153
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1.0
BACKGROUND AND INTRODUCTION
The purpose of this section is to describe the background of the U. S.
Environmental Protection Agency's (EPA's) regulation of cadmium air emission
sources and how this report relates to that regulation, to introduce the
objectives of this current cadmium study, to define what cadmium source
categories are included and why, and to describe how the remaining parts of
the background report are structured.
1.1
BACKGROUND
The U. S. Environmental Protection Agency, specifically the Office of
Ai~ Quality Planning and Standards (OAQPS), is currently assessing whether
cadmium is a hazardous air pollutant and should be regulated under
Sections 110, 111(d), or 112 of the Clean Air Act (CAA). Under Section 122
of the CAA, EPA is specifically required to determine if the emission of
cadmium into ambient air "will cause, or contribute to, air pollution which
may reasonably be anticipated to endanger public health." If this determi-
nation is positive, EPA shall "simultaneously with such determination
include such substance in the list published under Section 108(a)(1) or
112(b)(1)(A) (in the case of a substance which, in the judgement of the
Administrator, causes, or contributes to, air pollution which may reasonably
be anticipated to result in an increase in mortality or an increase in
serious irreversible, or incapacitating reversible, illness), or shall
include each category of stationary sources emitting such substance in
significant amounts in the list published under Section 111(b)(1)(A), or
take any combination of such actions."
As a part of this assessment and determination process, EPA must
examine whether cadmium is a hazardous air pollutant based on its health
effects and the degree to which the national population is exposed
1
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and put at risk to cadmium. In its health effects determination, EPA is
trying to ascertain whether exposure to airborne cadmium causes or increases
carcinogenic, irreversible, or incapacitating reversible illnesses in the
exposed population. The EPA's Office of Health and Environmental Assessment
(OHEA) is re~ponsib1e for conducting research into these areas for suspected
hazardous air pollutants and producing publically available health
assessment documents.
A draft health assessment document for cadmium has
been prepared by OHEA. The draft document was reviewed by EPA's Science
Advisory Board on October 22, 1984.
A regulatory decision on cadmium would consider not only health effects
as determined by OHEA, but also the levels of cadmium to which the relevant
population is exposed and the subsequent risk resulting from said exposure.
However, before an exposure/risk assessment can be performed, detailed
characterizations of the appropriate source categories must be made to
determine such necessary data as source emission rates, emission parameters,
and location. In addition to these factors, other s~urce category-specific
'factors such as ,the number of individual sources nationwide' and the contro1-
lability of existing emissions (i.e., what is the extent of current emissions
to which estimated best control is not being applied) are considered before
a determination is made to list a substance under Section 112 as a hazardous
pollutant. The total number of individual sources in a category is impor-
tant because the number may be low enough and localized enough that it does
not warrant EPA developing national emission standards for the source
category. A recent example of this situation is EPA's delegation of
acrylonitrile source control to the States containing acrylonitrile sources.
The controllability issue is important because if analyses determine
that all emission sources within a category are currently controlled with
the best available measures, then EPA has to question the feasibility' of
reasonably achieving additional emissions reduction (and subsequent risk
reduction) as a result of undertaking a Section 112 action.
2
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1.2
INTRODUCTION
The primary use for the information presented in the document is to be
an aid to EPA in its consideration and decision as to whether to list
cadmium as a hazardous air pollutant from the standpoint of the severity of
the health risks of cadmium emissions from individual source categories. In
terms of making a determination on listing, this report addresses the
factors relating to exposure/risk assessment. To facilitate an exposure/risk
assessment, this report provides data on the following topics for major
categories of cadmium air emissions.
Existing cadmium emission levels
Current number of plants and locations
Existing control equipment and its performance
Definition of estimated best controls
Additional controllability of existing emissions
The major categories of cadmium air emissions have
1-3
delineated in several past studies conducted by EPA.
categories are identified as follows.
essentially been
These source
-
Primary cadmium smelters
Primary copper smelters
Primary lead smelters
Primary zinc smelters
Secondary copper smelters
Secondary lead smelters
Secondary zinc smelters
Iron and steel facilities (including basic oxygen furnaces,
electric air furnaces, and open hearths)
Municipal incinerators, including modular
Sewage sludge incinerators
Cadmium pigment manufacturing
Cadmium stabilizer manufacturing
Coal and oil combustion sources
incinerators
Out of these 14 source categories, six are addressed in dept~ in this
document, including:
3
-------
Primary cadmium smelters,
Primary lead smelters,
Primary zinc smelters,
S~wage sludge incinerators,
Municipal incinerators, and
Cadmium pigments manufacturing.
These six source categories were determined to be deserving of additional
study based on prior analyses which indicated that their cadmium emissions
appear high enough to pose risks to the exposed populations. Several
sources within these categories do not have the estimated best controls in
place such that there is room for improved emissions reduction.
For each of the six source categories the following types of
information are developed and presented in Chapters 2 - 8 of this report.
A brief description of the basic source category processes,
including flow sheets.
A description of cadmium emission points within processes,
including a delineation of the nature of emis~ions as process or
fugitive and as particulates, aerosols, or vapors.
A determination of the chemical form of cadmium emissions.
Names and locations of known facilities.
A description of existing cadmium controls.
An estimate of current cadmium emissions.
A discussion of current regulations impacting cadmium control.
A description of control options that may represent estimated best
control (EBC) for each cadmium emission point.
An estimate of cadmium emissions under the scenario that EBC is in
place.
The least definitive part of this assessment is the estimation of cadmium
-,
emissions under the speculative scenario of EBC in place across a.source
category. For some source categories EBC emissions are not possible to
estimate because (1) EBC is not definable, (2) existing emissions are not
quantifiable, and/or (3) the existing prevalence of EBC in a source category
is unknown.
4
-------
The rationales for excluding the other eight source categories from the
more in-depth discussions of this report are varied, but they primarily
involve determinations that the predicted exposure/risk levels attributable
to these categories are relatively low or that estimated best control is
already in place in the categories, such that existing emissions cannot
reasonably be reduced further. Details and data supporting the decisions
not to include these eight source categories have been developed in previous
cadmium work conducted by Radian Corporation and the Pollutant Assessment
Branch of EPA. Most of these data are summarized in a series of technical
memos presented in Appendix A. Combustion sources are not covered in
Appendix A; however, EPA is specifically evaluating combustion sources
separately in another effort as sources of. cadmium and other trace metals
emissions such as nickel and chromium.
The format of the information to be provided in Chapters 2 - 8 is more
of a summary and general nature than detailed and itemized source-by-source
for the reason that the report is intended to educate a broad spectrum of
. .
. readers. The report is intended to provide abroad perspective to the
reader so that he or she may contrast the national implications of cadmium
sources against other pollutants under study by EPA. Plant or process
specific data are only presented when they are unique and have an important
bearing on cadmium emissions. Information duplication from previous studies
is attempted to be minimized by providing appropriate references when
necessary rather than restating the same data.
5
-------
1.3
REFERENCES FOR CHAPTER 1
1.
Survey of Cadmium Emission Sources. EPA-450/3-81-013. Office of Air
Quality Planning and Standards, U. S. Environmental Protection Agency,
Research Triangle Park, NC. September 1981.
2.
Co1eman~ R., et a1. Assessment of Human Exposure to Atmospheric
Cadmium. EPA-4S0/S-79-007. U. S. Environmental Protection Agency,
Research Triangle Park, NC. June 1979.
3.
Coleman, R., et a1. Sources of Atmospheric Cadmium. EPA-450/5-79-006.
U. S. Environmental Protection Agency, Research Triangle Park, NC.
August 1979.
6
-------
2.0
PRIMARY CADMIUM SMELTING
This chapter discusses the primary cadmium smelting industry and its
associated cadmium emissions. Section 2.1 presents a brief source category
description. Section 2.2 describes the basic. production processes and
identifies cadmium emissions sources. Section 2.3 discusses the existing
emission control techniques used at primary cadmium smelters. Cadmium
emissions estimates are presented in Section 2.4, and Section 2.5 presents a
discussion of EBC options and the potential cadmium emission reduction which
could be achieved by the application of EBC. The description of the primary
cadmium smelting industry is based on three trip reports and on the
available literature.
2.1
SOURCE CATEGORY DESCRIPTION
In 1984, five cadmium smelters were operating in the United States.
Four of the five are co-located at primary zinc plants, while the other is
located independently. All information discussed in this chapter pertains
only to the cadmium smelting portion of the co-located zinc and cadmium
plants. Emissions associated with the zinc smelting operations at the four
combined zinc and cadmium smelters are described in Chapter 4. The
locations and production capacities of the five cadmium smelters are shown
in Table 2-1.1-4 One of these, ASARCO/Corpus Christi, temporarily ceased
operations in 1982, but was reopened in 1984. Three other plants formerly
produced cadmium: New Jersey Zinc Company in Palmerton, Pennsylvania; St.
Joe Minerals Corporation in Monaca, Pennsylvania; and Bunker Hill Company in
Kellogg, Idaho. New Jersey Zinc and St. Joe currently produce zinc or zinc
oxide, but no longer produce cadmium. The Bunker Hill plant is closed and
has not announced any plans to reopen. In 1983, total domestic production
of cadmium metal was 1,050 Mg (1,160 tons), but at the end of the .third
7
-------
TABLE 2-1.
THE DOMESTIC PRIMARY CADMIUM SMELTERS
Production a
Capacity
Plant Location Mg!yr (Tons!yr)
~!Sauget Sauget, Illinois 408 (450)
ASARCO!Corpus Christi Corpus Christi, Texas 324 (358)
ASARCO!Globe Denver, Colorado 603 (665)
Jersey Miniere Clarksville, Tennessee 273 (300)
National Zinc Bartlesville, Oklahoma 275b (302)b
a - .
Capacity expressed in terms of cadmium equivalent of cadmium metal and
cadmium oxide. AMAX!Sauget and ASARCO!Globe produce both cadmium metal
and cadmium oxide. The other three plants produce only cadmium metal.
b
Capacity estimated as equivalent to 1979 production.
8
-------
quarter of 1984, production was already 1,160 Mg (1,280 tons).5 Part of
this increase is due to the reopening of ASARCO/Corpus Christi. Various
plants were operating between about 50 and 100 percent capacity in
124
1984. " Growth in this industry is expected to be relatively slow.
. The AMAX/Sauget plant is located in an industrialized area in the
alluvial plain across the Mississippi River from St. Louis. ASARCO/Corpus
Christi and ASARCO/Globe are also in industrialized areas near large cities.
ASARCO/Globe is on a plateau near Denver surrounded by mountainous terrain,
while ASARCO/Corpus Christi is located on flat terrain near the Gulf of
Mexico. Jersey Miniere Zinc is located on gently rolling terrain in
Clarksville, Tennessee, which has a population of about 30,000. National
Zinc is in Bartlesville, Oklahoma, which also has a population of about
30,000.
2.2
PROCESS DESCRIPTION
Cadmium metal and/or cadmium oxide can be produced as a byproduct of
roaster calcine leachate at zinc smelters or from lead smelter baghouse
dusts. In general, the process consists of precipitating a cadmium
"sponge," melting the cadmium sponge, and casting the molten cadmium into
rods, ingots, or balls. At two plants a portion of the molten cadmium is
further processed in retort furnaces to produce cadmium metal powder and/or
cadmium oxide. Figure 2-1 is a generalized flow diagram of the cadmium
production processes.
follows.
A more detailed description of these processes
Cadmium Precipitation and Purification
Zinc smelter roaster product (calcine) is leached in a weak sulfuric
acid solution, which dissolves the zinc and cadmium. Leach residues are
removed, and the zinc and cadmium-bearing solution undergoes further
purification, during which copper and other trace impurities are removed by
precipitation. Zinc dust is then added, which causes a cadmium cake to
precipitate. This cadmium cake may be redissolved, further purified by
9
-------
Weak
Sulfuric
Acid
Zn Dust
Purification
Steps
Cadmium Sponge
Precipitation
Cadmium
Casting
Cadinium
Metal Products
(Bricks. Ingots.
Sticks. Balls)
Zinc Roaster Calcine Or
Lead Smelter Baghouse Dusts
Leach Tanks
Purification
Steps
Cadmium
Precipitation
Cadmi um
Melting Kettles
Or ~urnaces
Retort
Furnaces
Cadmium
Meta I Powder
Packaging
Cadmi um Meta I
Powder Product
Purification
Steps
Cadinium Plating
In Electrolysis
Cells
Air
Retort
Furnaces
Cadmium Oxide
Powder Product
Figure 2-1.
Generic cadmium production flowsheet.
Note: The figure presents various options for cadmium production.
plant has all of these process steps.
10
No single
-------
chemical means, and then precipitated to produce a cadmium sponge which is
made into briquettes. At other plants, the cadmium cake is"releached,
impurities are precipitated, and the cadmium solution is sent to
electrolysis cells where cadmium metal sheets are plated out on cathodes.
Cadmium sheets are then stripped from the cathodes.
If lead smelter baghouse dust is used as a raw material, the dust is
leached, and various trace metal contaminants are precipitated out. A
cadmium sponge is then precipitated from the purified solution by the
addition of zinc dust.
Melting and Casting
The cadmium sponge or cadmium sheets which have been recovered from the
roaster calcine leachate or lead smelter baghouse dust are then melted in
melting pots or furnaces. The cadmium is melted under a layer of sodium
hydroxide or resin. This caustic layer prevents oxidation of the molten
cadmium metal and reduces cadmium emissions. The molten cadmium is then
cast or ladled into various shapes including bricks,ingots, rods, and
balls.
Cadmium Oxide Powder Production
Three of the five cadmium smelters produce only cadmium metal products,
while the other two, ASARCO/Globe and AMAX/Sauget, also produce cadmium
metal powder and/or cadmium oxide powder. At these two, the cadmium lugs or
bricks from the melting kettle are reheated in retort furnaces. In the
production of cadmium oxide, the cadmium fume leaving the retort furnace is
oxidized in air, and the cadmium oxide product is then captured in a
baghouse and packaged for sale. In the production of cadmium metal powder,
the neck of the retort is plugged and the cadmium metal powder is manually
1 2 6-10
removed from the retort at the end of the batch cycle. ' ,
Emission Sources
The main process sources of cadmium .emissions common to all cadmium
plants are the cadmium melting kettles or furnaces. The casting operation
11
-------
is also a potential cadmium emissions source at all five plants. At the two
plants where cadmium oxide is produced, the cadmium oxide product collection
baghouses are major process cadmium emissions sources. Bagging of the
cadmium oxi~e product is a source of process fugitive emissions at these
plants. Be~ause of these additional cadmium sources, plants which produce
cadmium oxide have significantly higher process cadmium emission rates than
those which produce only cadmium metal.
The storage and handling of the lead smelter baghouse dust raw
material, if applicable, and storage and handling of leach residues are
potential sources of fugitive cadmium emissions at some plants.
2.3
EXISTING CADMIUM EMISSION CONTROLS
Table 2-2 lists cadmium emissions sources and summarizes the types of
controls currently in place for each source. These sources and controls are
described below.
M'1. ',ting Operations
Process emissions from the cadmium melting kettles or furnaces are
controlled by baghouses at Jersey Miniere Zinc, National Zinc, and
ASARCO/Corpus Christi. At least one of these plants has a furnace hooding
system which includes ventilation at the charging/drossing port to control
2 8,10
process fugitive emissions. '
At the AMAX/Sauget plant, there are no particulate control devices on
the melting or holding furnace, and these sources have not been tested to
determine levels of particulate or cadmium emissions. The caustic layer
that rests on top of the molten cadmium in the furnaces would control
cadmium emissions to some extent; however, the level of emissions from
melting operations has not been quantified at any plant. Charging and
tapping operations at AMAX/Sauget are hooded and exhausted to the atmosphere
uncontrolled. 1 The melting kettles at the ASARCO/Globe plant are also
covered by a caustic layer and 'are hooded, with emissions exhausted to the
7
atmosphere uncontrolled. The hooding systems would reduce worker exposure
12
-------
TABLE 2-2.
CADMIUM EMISSIONS SOURCES AND EXISTING CONTROLS
IN THE PRIMARY CADMIUM SMELTING SOURCE,CATEGORY
Emissions Source
Existing Controls
Cadmium Melting Kettles or Furnaces
Hooding and Baghouses (3 plants)
Uncontrolled (2 plants)
Cadmium Casting Operations
Hooding and Baghouses (2 plants)
Uncontrolled (2 plants)
Unknown (1 plant)
Cadmium Oxide Collection Baghouse
and Packaging Operations
Hooding or Enclosure and
Baghouses (2 plants)
Fugitives from Materials Storage
and Handling, etc.
Enclosure and Ventilation to
Baghouses, and Wet Supression
(2 plants)
Confidential (1 plant)
Unknown (2 plants)
13
-------
to cadmium emissions by carrying the emissions outside of the building. No
estimates of cadmium emissions are available for the melting operations at
ASARCO/Globe and AMAX/Sauget.
Casting Operations
The cadmium casting operation at ASARCO/Corpus Christi is hooded and
ducted to the baghouse controlling emissions from the melting furnace.ll At
Jersey Miniere.Zinc. cadmium is ladled into molds. and emissions from this
operation are hooded and controlled by a baghouse.2 Emissions from similar
operations at AMAX/Sauget are uncontrolled.l At the ASARCO/Globe plant,
7
casting operation emissions are not controlled. The control status of
casting operations at National Zinc is unknown.
Cadmium Oxide Production
The cadmium oxide furnace baghouses are an integral part of the cadmium
oxide production p~ocess at both plants which make cadmium oxide. Their
. purpose is to c~pture product cadmium oxide powder. They are designed to'be
over 99 percent efficient in capturing particulates. However, some cadmium
oxide particulates would be emitted from these baghouses and be released
into the air.
Fugitive Emissions
Fugitive emissions sources and controls vary from plant to plant. For
example, at Jersey Miniere Zinc. the precipitated cadmium cake is dried
before re-Ieaching (see Section 2.2) and this is a potential fugitive
emissions source; however, this operation is performed inside the cadmium
plant building.2 At the AMAX/Sauget plant, handling of leach residues is a
potential fugitive cadmium emissions source. However, residues ar~
sometimes handled wet. and when they are handled dry the transfer points are
hooded and ducted to a baghouse. Cadmium briquettes are also kept wet to
minimize fugitive emissions from storage and handling. The cadmium oxide
plant at AMAX/Sauget. including packaging operations, is enclosed and
14
-------
maintained under negative pressure,
In general, fugitive emissions from
cadmium plants are well controlled.
At ASARCO/Globe. process fugitives from the cadmium oxide packing
7
station are hooded and ducted to a baghouse. Information on other
potential fugitive cadmium emissions sources and controls at the
ASARCO/Globe plant is available, but has been declared confidential.4
is a lack of information on the status of fugitive emissions control at
National Zinc and ASARCO/Corpus Christi.
1
and emissions are ducted to baghouses.
the AMAX/Sauget and Jersey Miniere
There
2.4
EXISTING EMISSIONS
Total annual emissions from the five cadmium plants are estimated to be
about 8.2 Mg/yr (9.1 tons/yr).4 Over 99 percent of these emissions are from
the two plants which produce cadmium oxide. Only point sources were
included in these estimates, since there are no data on which to base
fugitive emissions estimates. The cadmium emissions calculations for this
industry are ~ontained in confidential files maintained by the Pollutant
Assessment Branch of EPA's Office of Air Quality Planning and Standards.4
The emissions sources included in the source category cadmium emission
estimates are the cadmium oxide furnaces at ASARCO/Globe and AMAX/Sauget,
the packing station baghouse at ASARCO/Globe, and the cadmium melting
furnaces at the other three plants. Emissions from the cadmium melting
kettles or furnaces at AMAX/Sauget and ASARCOIGlobe were not included
because there were no data on which to base estimates. These two plants do
not have baghouses on the melting operations, however the layer of caustic
would control emissions to some extent. It is believed that emissions from
the melting operations at Sauget and Globe would be small compared to
emissions from the cadmium oxide furnaces at these plants.
Cadmium emissions for the ASARCO/Globe and AMAX/Sauget baghouses were
1 7 12
calculated from baghouse exhaust gas flowrates " by assuming an outlet
particulate loading of 0.005 gr/dscf. This value is typical of particulate
emissions from well-operated baghouses. It was assumed that particulate
15
-------
emissions escaping the cadmium oxide furnace baghouses and product packaging
station are composed of cadmium oxide. which is 87.5 weight-percent cadmium.
Continuous operation of these baghouses was also assumed.
Emissions from the melting furnace baghouse at Jersey Miniere Zinc were
estimated qased on cadmium emissions tests at that source.2 Cadmium
emissions from melting operations at National Zinc were based on estimates
by that company.l0 Emissions from the melting and casting operations
baghouse at ASARCO/Corpus Christi were assumed to be similar to the above
tw~ plants. since the process and controls are similar. The melting and
casting operations baghouse at ASARCO/Corpus Christi was recently tested for
particulate and cadmium emissions. and results should be available in early
1985.8
2.5
ESTIMATED BEST CONTROL (EBC) RECO~~ENDATION
2.5.1
Recommended EBC
Cadmium EBC recommended for the primary cadmium smelting industry would
include baghouse control of all process cadmium emissions sources. Hooding
and baghouses would be recommended for melting kettles and furnaces and for
holding furnaces. These systems should include hooding of charging and
tapping operations. if applicable. Cadmium oxide product collection
baghouses are used as a part of the production process at the two plants
producing cadmium oxide. Packaging of the cadmium oxide should also be
hooded or enclosed. with emissions ducted to a baghouse.
Fugitive cadmium emission sources and EBC controls vary from plant to
plant due to the diversity of plant types within the primary cadmium
smelting industry. The lead smelter baghouse dust used as a raw material at
one plant should be shipped enclosed in bags and stored in a building. Any
dusty cadmium-containing intermediates or waste materials should be stored
in enclosed areas. Materials handling and conveying equipment should be
enclosed and ventilated. Melting kettles and furnaces should be properly
enclosed or hooded and ventilated to control process fugitive em~ssions.
All ventilation gas streams should be treated with baghouses.
16
-------
2.5.2
Prevalence of EBC
Table 2-3 summarizes the status of control for each plant with regard
to cadmium EBC.
Miniere Zinc and
National Zinc.
Cadmium EBC is in place for all process sources at Jersey
ASARCO/Corpus Christi and for melting operations at
Cadmium EBC is not in place for all process sources at
AMAX/Sauget and ASARCO/Globe. The melting and casting operations at these
two plants are uncontrolled; however, the cadmium oxide portions of these
two plants, including the cadmium oxide baghouse and product packaging
operations, are controlled with EBC.
In general, fugitive emissions are controlled to near EBC at Jersey
Miniere. Materials handling is controlled with EBC at AMAX/Sauget, but
process fugitives from the melting operations are uncontrolled. The degree
to which EBC is used to control cadmium fugitive sources at ASARCO/Corpus
Christi and National Zinc is unknown. Information on fugitive controls at
ASARCO/Globe has been declared confidential so the prevalence of EBC at this
4
plant is not discussed here.
2.5.3
EBC Emission Levels
Application of EBC to all process sources would not substantially
reduce the existing cadmium emissions estimate for the cadmium smelting
source category of 8.2 Mg/yr (9.1 tons/yr) because over 99 percent of these
emissions are from the cadmium oxide furnace baghouses and cadmium oxide
packaging station baghouses at the two plants producing cadmium oxide, and
these sources are already controlled with EBC.
Application of fugitive EBC systems could reduce cadmium emissions at
some plants, but since there are no estimates of the current magnitude of
fugitive cadmium emissions, the potential reduction cannot be quantified.
17
-------
TABLE 2-3.
PREVALENCE OF CADMIUM EBC IN THE
PRIMARY CADMIUM SMELTING SOURCR
CATEGORY
Prevalence of Cadmium EBC
Plant Process Sources Fugitive Sources
AMAX/Sauget Most sources at EBCa Most sources at EBCa
ASARCO/Corpus Christi All sources at EBC Unknown
ASARCO/Globe b Confidential
Most sources at EBC
Jersey Miniere All sources at EBC All sources at EBC
National Zinc Some sources at EBC,c Unknown
Others unknown
aCadmium melting and holding furnaces and casting operations are
uncontrolled. Cadmium oxide production and packaging operations are
controlled with baghouses, which are EBC for cadmium emissions.
b .
Melting and casting operations are uncontrolled. Cadmium oxide production
and packaging are controlled with baghouses, which are EBC for cadmium
emissions.
~elting operations are controlled with baghouses, which are EBC. There is
no information on control of the casting operations.
18
-------
2.6
REFERENCES FOR CHAPTER 2
1..
Trip report. Miles, A. J. and L. E. Keller, Radian Corporation, to
file. April 13, 1984. 5 p. Report of visit to AMAX Zinc Company
primary zinc/cadmium plant in Sauget, Illinois.
2.
Trip report. Keller, L. E. and A. J. Miles, Radian Corporation, to
file. April 11, 1984. 10 p. Report of visit to Jersey Miniere Zinc
Company primary zinc/cadmium smelter in Clarksville, Tennessee.
3.
American Bureau of Metal Statistics, Inc.
Statistics. 1979.
Non-Ferrous Metal
4.
Confidential files on Cadmium and Zinc Smelting. Contains two trip
reports and four memos on emissions calculations. Maintained by the
Pollutant Assessment Branch, Strategies and Air Standards Division,
Office of Air Quality Planning and Standards, U. S. Environmental
Protection Agency. Research Triangle Park, NC. 1984.
5.
U. S. Bureau of Mines. Mineral Industry Surveys. Cadmium, Quarterly.
Washington, D. C., U. S. Government Printing Office. August 1984.
6.
ASARCO's Corpus Christi Zinc Plant, Engineering and Mining Journal 18~:
114. September 1981.
7.
Colorado Department of Health, Air Pollution Control Division.
Pollutant Emissions Notices: ASARCO, Incorporated. 1983.
Air
8.
Telecon. Keller, L. E., Radian Corporation, with R. Cardenas, ASARCO,
Inc. December 6, 1984. ASARCO/Corpus Christi cadmium plant.
9.
Telecon. Thorington, M. C., Oklahoma State Air Quality Service, with
R. C. Mead, Radian Corporation. November 19, 1984. Emissions from
National Zinc.
10.
Letter and attachments from Thorington, M. C., Oklahoma State Air
Quality Service, to Mead, R. C., Radian Corporation. November 29,
1984. 1 p. Information on National Zinc Company's emissions.
11.
Telecon. Mead, R. C., Radian Corporation, with Martin, T., ASARCO,
Inc. December 7, 1984. Emissions controls at ASARCO/Corpus Christi.
12.
Telecon. Dennis, P., Illinois Division of Air Pollution Control, with
R. C. Mead, Radian Corporation. November 9, 1984. Stack parameters
for ASARCO/Hillsboro and AMAX/Sauget.
19
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3.0
PRIMARY LEAD SMELTING
This chapter discusses the primary lead industry and its associated
cadmium emissions. Section 3.1 presents a brief source category
description. Section 3.2 describes the basic production process and
identifies cadmium emission sources. Section 3.3 discusses the existing
emission control techniques used at primary lead smelters. Cadmium
emissions estimates are presented in Section 3.4, and Section 3.5 presents a
discussion of EBC options and the potential emission reduction which could
be achieved by the application of EBC. The description of the lead smelting
industry is based on two plant visits and on the available literature.
3.1
SOURCE CATEGORY DESCRIPTION
There are five primary lead smelters in the United States which
produced a total of 449,000 Mg (496,000 tons) of lead in 1983. This
accounted for 39 percent of the total domestic demand for lead in that
1
year. Most of the remaining demand was filled by domestic secondary lead
smelters. The five primary lead smelters, their locations, and production
capacities are shown in Table 3-1.2.3.4 Three of the five smelters are
located in or near small towns, while St. Joe/Herculaneum is about 12 miles
from St Louis and the ASARCO/El Paso smelter is located near large
population centers (El Paso. Texas and Ciudad Juarez, Mexico). The
topography around the plants varies from nearly flat to mountainous. In
1984, the five plants were operating between about 78 and 100 percent
capacity, and no plans for expansion of capacity or opening of new plants
3 4
have been announced.' The growth potential of the source category is low.
20
-------
TABLE 3-1.
THE DOMESTIC PRIMARY LEAD SMELTERS
a
Production Capacity
Plant: Location Mg/yr (Tons/yr)
I
ASARCO/East Helena East Helena, Montana 82,000 (90,000)
ASARCO/El Paso El.Paso, Texas 82,000 (90,000)
ASARCO/Glover Glover, Missouri 100,000 (110,000)
AMAX/Boss Boss, Missouri 127,000 (140,000)
St. Joe/Herculaneum Herculaneum, Missouri 204,000 (225,000)
a
Capacity figures listed in terms of lead produced per year.
21
-------
3.2
PROCESS DESCRIPTION
The materials processed at the U. S. primary lead smelters are
predominantly lead sulfide ore concentrates. The most important
lead-containing mineral in the ore concentrates is Galena (PbS). Raw lead
ore as mined is typically 3 to 6 percent lead by weight, and gravity/
flotation methods are used to concentrate the ore. Three types of lead ore
concentrates are smelted in the United States: Missouri lead ore
concentrates, which account for about 80 percent of domestic primary lead
production, western lead ore concentrates, and foreign lead ore
concentrates. Lead ore concentrates from the Missouri lead belt typically
contain about 75 percent lead and 15 percent sulfur by weight, with silver,
copper, zinc, iron, calcium, magnesium, arsenic, and acid-insoluble material
making up most of the remaining 10 weight percent.
Western lead ore
concentrates are of poorer quality than Missouri lead ore concentrates and
contain about 45 percent lead, 10 to 30 percent sulfur, up to 15 percent
I .
zinc~ 8 percent iron, and 3 percent copper. Other constituents of western
lead ore concentrates include gold, silver, calcium, magnesium, antimony,
bismuth, and arsenic.2 The cadmium content of Missouri lead are concentrate
is typically
are is about
about 0.02 weight percent, while the cadmium content of Western
3 4
0.1 weight percent.' Ore concentrate unloading, storage, and
potential sources of cadmium emissions at primary lead
handling are
smelters.
As shown in Figure 3-1, primary lead smelting is a complex process with
several distinct operations. The three key operations common to all U. S.
primary lead smelters are sintering, blast furnace reduction, and drossing.
At three plants the dross is treated in a dross reverberatory furnace, while
at two plants an alternative sodium addition technique is used to remove
copper from the dross. Other process equipment may include a slag fuming
furnace, a deleading kiln, and a lead refinery. Impure lead bullion
produced by the smelting process can either be refined on-site (as is the
case for the Missouri lead smelters) or shipped elsewhere for refining (as
is the case for ASARCO/East Helena and ASARCO/El Paso). One plant also has
22
-------
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1 II I:AS
51H1"t:lI
0."' :AS
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HIli ,\I'" IIFt":A.<;
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----------------------------------------- ----------------------------- ---------1
!
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. DROSS ----
SIAl: :
8\11(: t"ll.n:R IIUST fABRH: nltllHC ' REVEIIBt:RAI0RY --~
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. ----"
.
.
.
ESTERN QRE SMELTERS ONLY I
.
.
.
--------~~----~------------------------------------ .
--------------------------~
N
W
r------
.
.
.
.
I
t
I
r
.
.
.
.
.
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'-------
'"A
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Figure 3-1.
Primary lead smelting.
EVEllIlf.RA1UIIY
CE OffrJ.,5
OSSEIJ BIII.UON
to RU'IHERY
SUG
HATTE
SPEISS
I.EAD
-------
a Godfrey roaster, which is used to concentrate the cadmium content of blast
furnace baghouse dusts prior to shipping elsewhere for cadmium recovery.
Each step in the smelting process is described below.
Sintering
The first step in the processing of lead ore concentrates is sintering,
which is carried out in an oxidizing atmosphere at a temperature of about
600°C (l,lOO°F). Lead sintering is essentially a roasting operation that
also serves to agglomerate the feed materials into a form suitable for blast
furnace reduction. Several functions are performed by lead sintering:
(i) a large portion of the sulfur in the ore concentrate is removed as.
S02 or S03' thereby allowing for the operation of a low
temperature, high efficiency blast furnace operation;
(ii) readily melting complex silicates are formed that agglomerate the
charge into a hard, porous blast furnace feed; and
(iii) species such as cadmium, arsenic trioxide, and antimony trioxide
are removed by volatilization.
Updraft-type sintering machines are generally used in the domestic lead
smelting industry although one plant has an updraft/downdraft sinter
machine. In updraft machines, the ore concentrate charge is spread onto the
grate belt. Air is introduced through wind-boxes located below the sinter
charge and passes through the charge to participate in the sintering
oxidation reactions. The sintering reactions are sufficiently exothermic to
sustain the desired temperature of 600°C (l,lOO°F) once the charge is
ignited. Approximately 80 percent of the sulfur in the ore concentrate is
eliminated as 802 from the sintering machine. The product sinter is
. 2,3,4
screened to remove fines and sent to the blast furnace.
Process offgases from the sinter machine contain a significant amount
of cadmium. However, at four of the five smelters contact sulfuric acid
plants and the associated gas precleaning equipment are used to treat all or
part of the sinter machine offgases. The sulfuric acid is recovered for
economic reasons. Baghouses are used to treat the remainder of the sinter
offgases at all five plants. Controls on sinter process emissions will be
discussed .in detail in Section 3.3.
24
-------
Process fugitive emissions from the sinter plant include emissions from
sinter feed preparation. This includes crushing of return sinter product,
mixing, and handling. There may also be uncaptured fugitive fumes from the
sinter machi~e. Some process fugitives are captured with hooding and ducted
to control devices, and other sources are enclosed or partially enclosed in
buildings. These controls will be described in the next section.
Blast Furnace Operations
Screened sinter product is mixed with coke, recycled blast furnace
slag, silica, lime, and recycled flue dust and is fed to the blast furnace.
At the operating temperature of the blast furnace (980° to l,035°C) the
charge exists in a molten state, and several oxidation/reduction type
metallurgical reactions occur. Lead oxide is reduced to metallic lead by
the action of coke. Iron oxide is reduced to metallic iron which in turn
reduces lead sulfide and lead oxide to metallic lead.
The net result of the
blast furnace reactions is the production of a metallic lead-rich phase
called the lead bullion and a slag phase containing complex silicates of
iron, calcium, zinc, magnesium, and aluminum oxides. Depending on the
non-lead impurity levels of the ore concentrate and on the operation of the
furnace, a copper-rich phase called matte and a copper/iron/antimonyl
arsenic-rich phase called speiss can also be formed. In most cases lead
bullion and slag represent the major products from the blast furnace. They
separate on the basis of their mutual insolubility, and the slag layer
floats above the lead bullion.2
Blast furnace offgases are a cadmium emissions source, and a large
portion of the cadmium entering the lead smelting process has been observed
to concentrate in the blast furnace baghouse dusts. Because of the high
cadmium levels in blast furnace emissions, blast furnace upsets may be a
significant source of fugitive emissions. These upsets are usually caused
by uneven distribution of air within the furnace shaft, which can result in
channeling of combustion gases through "blow holes" in the charge materials.
Surges of combustion gas flow then occur at the top of the furnace, which
overloads the design ventilation capacity at that location. Efforts to
25
-------
reduce lead and cadmium emissions from blast furnace upsets have focused on
imp~oved tuyere air control. Fugitive emissions from blast-furnace charging
and tapping and materials handling also contain cadmium.
Slag Fuming
Blast furnace slag contains variable amounts of lead and zinc.
Low-zinc slag produced at the Missouri lead smelters is partially discarded
and partially recycled to the sinter machine for recovery of the lead value.
If the slag contains appreciable amounts of zinc, which is typical of
ASARCO/EI Paso and East Helena, it can be sent to a slag fuming furnace
where zinc oxide and lead oxide are recovered. However, slag fuming
operations at one of these two plants are currently inoperative, and the
status of fuming operations at the other plant is unknown. The slag fuming
furnace offgas streams are a source of cadmium emissions.
Drossing .
. Lead bullion from the blast furnace. is sent to a drossing'kettle where
the molten bullion is cooled, thereby reducing the solubilities of the.
various contaminants entrained and dissolved in the lead. A dross phase
forms on the surface of the lead that consists of lead oxide and other metal
oxides. The dross is skimmed from the surface and may be sent to a dross
reverberatory furnace, where it is treated with additional reagents to
produce as many as four phases: slag, matte, speiss, and lead. Dross
furnace slag is recycled to the blast furnace, matte and speiss (when
formed) are shipped to a copper smelter, and lead is recycled to the dross
kettle. At two plants, the dross furnace is no longer in use. It has been
replaced by a new dross treatment technique which involves liquid sodium
addition to lead bullion in the dross kettle. The sodium reacts with copper
in the lead bullion to form a sodium-copper matte that is skimmed off. The
234
matte may be sold to other smelters for copper recovery. ' ,
26
-------
Refining
Drossed lead contains a variety of impurities that must be removed by
lead refining. The three Missouri lead smelters refine lead on-site, while
the ASARCO/East Helena and ASARCO/EI Paso smelters ship their drossed
I
bullion to the ASARCO lead refinery in Omaha, Nebraska. Lead refining can
be a very complex operation and is highly dependent on the level and types
of impurities present. Domestic lead refineries employ pyrometallurgical
processes (furnace-kettle refining) that are generally based on two impurity
removal strategies:
(i) Drossed bullion impurities such as antimony, arsenic, and tin are
more readily oxidized than is lead. They can be removed by
oxidation/volatilization or oXidation/slagging techniques.
(ii) Drossed bullion impurities such as gold, silver, copper, and
bismuth can be removed in the form of insoluble intermetallic
compounds with the added reagents zinc, calcium, and magnesium.
The final product of a lead refinery contains greater than 99 percent pure
. 2. . '. .
lead. . Process arid fugitive offgases from lead refining are a minor source
of cadmium emissions.3,4
Godfrey Roaster Operations
At one plant, blast furnace/dross reverberatory furnace baghouse dust
is roasted in a Godfrey roaster to produce a high grade cadmium fume
(60 weight percent cadmium). The fume which is entrained in the roaster
offgas stream is captured in a baghouse, emptied into sacks, and shipped to
another plant for cadmium recovery. The roaster baghouse is a significant
4
source of cadmium emissions at this plant.
Fugitive Sources
Other fugitive cadmium emissions sources at lead smelters may include
slag or waste material storage piles, baghouse dust handling, and
resuspension of cadmium-containing dust from plant property (especially
roads).
27
-------
3.3
EXISTING CONTROLS
Process emissions sources at primary lead smelters are typically well
controlled. Fugitive controls vary from plant to plant. Table 3-2 lists
emissions sources and current controls. Controls on cadmium emissions
sources are discussed below in the same order the process and emission
sources were presented in Section 3.2.
Ore Handling and Storage
Fugitive emissions associated with lead ore handling and storage at
primary smelters are controlled by ventilated enclosure systems and/or wet
suppression methods. Ore transfer points are generally hooded and vented to
baghouses or venturi scrubber systems.
Sintering
Four of the five operating primary lead smelters use contact sulfuric
acid plants and the associated gas pre-cleaning equipment to treat some of
all of the sinter machine offgases. Typically, the gas pre-cleaning
equipment includes an ESP followed by a venturi scrubber. The ASARCO/Glover
lead smelter has no sinter machine S02 control. Sinter machine offgases at
ASARCO/Glover are sent to a spray chamber/baghouse system operated at 125°C
(257°F) for particulate control only.S,6 Three of the four smelters with
acid plant units (ASARCO/East Helena, AMAX/Boss, and St. Joe/Herculaneum)
treat two separate offgas streams from the sinter machine. A concentrated
802 offgas stream is removed from the inlet end of the sinter machine and
treated in an acid plant circuit, and a dilute 802 offgas stream is removed
from the outlet end of the sinter machine and treated in a baghouse operated
at 100° to 125°C (212° to 257°F).3,7,8 It is not economically feasible to
treat the entire offgas stream from a lead sintering machine with a contact
sulfuric acid plant unless a technique is used to increase the S02 content
of the stream to an acceptable level of 3.5 percent S02 or greater. The
ASARCO/EI Paso lead smelter makes use of a sinter machine offgas
recirculation technology that allows for the production of a single sinter
28
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TABLE 3-2.
CADMIUM EMISSIONS SOURCES AND EXISTING CONTROLS
IN THE PRIMARY LEAD SMELTING SOURCE CA~EGORY
E1;1lission Source
Existing Controls
Process Sources:
Sinter Machine
Acid plants (preceded by ESP's
and scrubbers)
Baghouses
Blast Furnace
Baghouses
Slag Fuming Furnace
Baghouses
Dross Reverberatory Furnaces
Baghouses
Drossing and Refining Kettles
No controls/Baghouses
Godfrey Roaster
Baghouse
Fugitive Sources:
Ore Storage, Handling
and Conveying
Enclosure and ventilation
to baghouses or scrubbers,
wet suppression, some open
storage
Sinter Preparation and
Returns Circuit
Enclosure, hooding, and
ventilation to baghouses
or scrubbers
Sinter Machine Fugitives
Enclosure, hooding, and
baghouses
Blast Furnace Fugitives
Enclosure, hooding, and
baghouses. Tuyere air
control systems.
Drossing Fugitives
Enclosure, hooding, and
baghouses
Miscellaneous Materials,
Storage, and Handling
Enclosure and ventilation to
baghouses, wet suppression,
some open sources
Dust Resuspension
Road cleaning and sweeping
29
-------
offgas stream containing 4 to 5 percent 502' The entire sinter machine
offgas stream at ASARCO{El Paso is treated in a contact sulfuric acid plant
circuit.9
'Hooding and enclosure of emission points followed by particulate
removal using baghouses or wet scrubbing systems are the commonly used
fugitive control techniques associated with sinter preparation and recovery.
Sinter machine fugitive discharges are generally controlled by total or
partial enclosure of the operation.
Blast Furnaces
Blast furnaces are typically controlled with baghouses. The S02
content of blast furnace offgas is typically on the order of 0.05 volume
percent, which is too low to be treated in a contact sulfuric acid plant.
Particulate removal at all five domestic primary lead smelters is
accomplished using baghouses operated over the temperature range of 100° to
125°C (212° to 257°F). Fugitive emissions from blast furn~ce operations are
controlled by building enclosure of the source and by the use of fixed or
movable hoods for furnace tapping and charging operations. Fugitive
emissions from blast furnace upsets can be reduced by improving tuyere air
control.
Slag Fuming
The slag fuming furnace offgas streams at ASARCO/El Paso and
ASARCO/East Helena are controlled with baghouses. The operational
temperature of the baghouses is not known explicitly, but is assumed to be
low (100° to 125°C (212° to 257°F)] by analogy to the operation of baghouse
2
systems on the other lead smelter process offgas streams.
Drossing
Dross kettle and dross furnace process offgases (at plants where dross
furnaces are used) contain very small amounts of 502' They are generally
combined with blast furnace offgases and treated for particulate and fume
30
-------
removal in baghouses operated over the temperature range of 100° to 125°C
(212° to 257°F). Fugitive emissions from the drossing kettles are generally
controlled by building enclosure or kettle hooding systems.
Refining
Offgases from lead refining and other miscellaneous potential sources
of cadmium emissions at primary lead smelters are either uncontrolled or
controlled with ventilation systems ducted to baghouses.
Godfrey Roaster
One plant has a Godfrey roaster. Blast furnace/dross furnace baghouse
dusts are stored in an enclosed, ventilated shed, and then conveyed to the
Godfrey roaster by an enclosed, ventilated conveyor. Emissions from both
sources are controlled by a baghouse. Cadmium fume from the roaster is
captured in a baghouse with a cupola discharge. Captured fume is then
emptied .into supersacks which are stored in a shed prior to shipment for
4 . .
cadmium recovery. .
Applicable Regulations
Existing regulations which have a direct effect on cadmium emissions
from the lead smelting industry are the new source performance standards
(NSPS) for S02 and particulate matter; SIP emission limitations for 502'
particulate matter, and lead; and Occupational Safety and Health Adminis-
tration (OSHA) workplace exposure limits for lead, arsenic, and cadmium.
The lead smelters are currently improving controls in order to comply with
lead SIP's. Fugitive and process fugitive emissions controls are being
especially affected by the SIP's. For example, lead SIP's applicable to two
primary lead smelters (ASARCO/East Helena and ASARCO/El Paso) resulted in
the installation of computer-automated blast furnace tuyere air controls to
reduce fugitive lead emissions from the blast furnace. Since cadmium tends
to be concentrated in blast furnace particulate matter, the computerized
tuyere air controls will also result in significant fugitive cadmium
emissions reduction. The three ASARCO smelters have also signed so-called
31
-------
"tripartite" agreements with OSHA and the United Steel Workers Association
(USWA) that will result in improved fugitives control. The. tripartite
agreements detail specific engineering and work practice controls that will
be installed at the ASARCO smelters to reduce employee exposure to lead and
10 11 12
inorganic arsenic. " These controls will also result in reduced
exposure to cadmium. For example, the tripartite agreement for the
ASARCO/East Helena plant sets out an agreed upon schedule for ventilation
improvement in the drossing and reverberatory furnace department. This
agreement is likely to result in a new ventilation system to reduce process
fugitive lead emissions from the top holes in the dross reverberating
furnace. Since cadmium is present in the dross fed to the furnace, the new
ventilation system will also result in a decrease in process fugitive
cadmium emissions from this source. The other two lead smelters (St. Joe
and AMAX) are expected to sign such agreements in the future.
3.4
EXISTING EMISSIONS
Total annual cadmium emissions from the five primary lead smelters are
estimated to be 26.5 Mg/yr (30.4 tons/yr). This includes about 19.0 Mg/yr
(21.8 tons/yr) of controlled point source emissions and 7.5 Mg/yr (8.6 tons/yr)
4
of fugitive emissions. The largest point sources of cadmium emissions are
baghouses controlling sinter machine offgases and blast furnace offgases. '
Baghouses controlling dross reverberatory furnaces at three plants and a
baghouse controlling the Godfrey roaster at one plant also contribute
significantly to point source emissions. Other point sources include
scrubbers and baghouses controlling the sinter preparation and returns
circuits. The specific types of sources vary from plant to plant.
Cadmium emissions test data are available for the main stacks at
AMAX/Boss and St. Joe/Herculaneum and the sinter, zinc fume, and blast
furnace/dross furnace baghouses at ASARCO/East He1ena.3,4,8 Estimates of
cadmium emissions from major point sources at ASARCO/G1over and ASARCO/El Paso
32
-------
and for minor point sources at other plants were derived by applying
cadmium/lead ratios to lead emissions estimates developed for SIP's.
Cadmium/lead ratios were obtained from testing of various materials and
baghouse dusts at several plants, but since some of these ratios are
confidential', they are not presented here. Cadmium emissions calculations
for each plant are documented in the confidential files.4
Non-point source emissions included in the cadmium emissions estimates
include process and area fugitives. Process fugitives escape from the
semi-enclosed buildings containing the sinter operations, blast furnace
operations, lead pouring and dross kettles, reverberatory furnaces, and zinc
fume furnaces. Raw materials and baghouse dust handling, storage, conveying,
and mixing are also sources of fugitives. Area fugitive sources
include outside storage of ore and slag, and on-property dust resuspension.
Blast furnace upsets. which may be a significant source of cadmium fugitive
emissions, were not included in the emissions estimates because there was
not enough information to develop reliable quantitative emissions estimates.
This source was estimated to be the largest single fugitive lead emissions
source in the SIP for one plant, but was not listed in the SIP lead emissions
inventories for the other plants.
Fugitive cadmium emissions estimates for the ASARCO/East Helena and
ASARCO/Glover facilities were based on exposure profile sampling for cadmium
conducted by Midwest Research Institute (MRI).4,13 Values for some fugitive
sources were updated based on lead SIP's and cadmium/lead ratios because
4
some controls have been improved since MRI's testing. Fugitive emissions
at other plants were calculated on a plant by plant basis from lead emissions
estimates by applying cadmium/lead ratios. The lead emissions estimates
were based on lead SIP's. These estimates had been derived by the State
agencies using a variety of methods including testing for lead or particu-
lates, ambient monitoring, and/or engineering judgement. Cadmium/lead
ratios were obtained from trip reports, telephone conversations with plant
personnel, and testing of raw materials, various intermediates and waste
materials, and baghouse dusts and emissions. Since many of the fugitive
emissions calculations are based on confidential data, they are documented
in the confidential files rather than in this report.4
33
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3.5
ESTIMATED BEST CONTROL (EBC) RECOMMENDATIONS
3.5.1
Recommended EBC
Cadmium EBC for process emissions sources would include acid plants
with the associated gas pre-cleaning equipment, and baghouses. Contact
sulfuric acid plants and the associated gas pre-cleaning systems are recom-
mended for the treatment of concentrated 802 offgas streams produced in the
lead sintering operation. The gas pre-cleaning equipment, which includes an
ESP followed by a venturi scrubber, is effective at particulate and cadmium
removal. The S02 concentrations of the remaining offgas streams at primary
lead smelters are too low to make contact sulfuric acid plants a viable EBC
option for these streams. Baghouses are recommended as cadmium EBC for
offgases generated by blast furnaces, dross furnaces, zinc fuming furnaces,
and lead refining processes. Since cadmium is a relatively easily volatilized
metal, baghouses operated at fairly low temperatures are theo~ized to be the
.most effective means for controlling cadmium emissions. However, no data
for cadmium emissions exists to demonstrate the effectiveness of lowered
baghouse temperatures. Currently, in the primary lead industry, no baghouses
controlling these processes are known to operate above 204°C (400°F).
Cadmium EBC for fugitive emissions in the primary lead smelting industry
consists of enclosing ore storage areas, ventilating and/or enclosing
material transfer points, ventilating and/or enclosing furnace operations,
and treating all of the ventilation gas streams with baghouses.
techniques to be applied will vary on a plant by plant basis due
diversity within the lead smelting industry.
The specific
to the
3.5.2
Prevalence of EBC
Table 3-3 summarizes the prevalence of use of EBC systems at primary
lead smelters.
Cadmium EBC is in place for process emission sources at each of the
five domestic primary lead smelters. The application of EBC for process
34
-------
TABLE 3-3.
PREVALENCE OF CADMIUM EBC IN THE PRIMARY
LEAD SMELTING SOURCE CATEGORY
Prevalence of EBC
Plant Process Sources Fugitive Sources
ASARCO/East Helena All sources at EBC Most sources at EBCa
ASARCO/El Paso All sources at EBC Most sources at EBCa
ASARCO/Glover All sources at EBC Most sources at EBCa
AMAX/Boss All sources at EBC Most sources at EBCa
St. Joe/Herculaneum All sources at EBC Most sources at EBCa
a
See Section 3.5 for a discussion of the prevalence of EBC systems for
fugitive .sources. and Table 3-2 for a listing of some major fugitive
sources and current controls. There are numerous fugitive emissions
sources. At each plant most are controlled with EBC. however there are
some sources at each plant which are not currently at EBC. State
implementation plans and tripartite agreements with OSHA have been signed
which will result in the application of EBC to all fugitive sources.
35
-------
sources has been motivated by existing SIP emission limitations for S02 and
particulates.
Cadmium EBC is in place at most fugitive emission sources at the five
smelters, and the OSHA agreements and lead SIP's are expected to result in
improved controls at some sources not currently at EBC. One example of a
fugitive source which is not well controlled is baghouse dust handling at
one plant. The cadmium content of the dust is high, and dust is transferred
from the dust cellar of the baghouse to a storage' shed using a front end
loader. Significant dust accumulation occurs near the baghouse. At another
plant, ore storage emissions are not at EBC because part of the ore is
stored outside rather than enclosed in buildings.33
3.5.3
EBC Emissions Levels
Control of a few minor cadmium emission sources, such as the two
discussed above, could be improved. However, the application of EBC to
these sources is not likely to significantly reduce cadmium emissions from
the primary lead smelting industry. This situation exists because all
process and most fugitive emission sources at every plant are currently at
EBC. Furthermore, in most cases where EBC for fugitive emissions is not
currently in place, plants will be required to upgrade controls to comply
with OSHA tripartite agreements and lead SIP's, such that EBC is expected to
soon be in place.
36
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3.6
REFERENCES FOR CHAPTER 3
1.
U. S. Bureau of Mines. Mineral Industry Surveys. Lead.
Washington, D. C., U. S. Government Printing Office.
February 1984.
2.
Radian ~orporation. Preliminary Study of Sources of Inorganic Arsenic.
Prepared for U. S. Environmental Protection Agency. Research Triangle
Park, N. C. Publication No. EPA-450/5-82-005. August 1982.
p. 51 - 56.
3.
Trip report. Miles, A. J. and L. ~. Keller, Radian Corporation, to
file. April 12, 1984. 8 p. Report of visit to AMAX. Homestake Lead
ToIlers, a primary lead facility in Boss, Missouri.
4.
Confidential files on Lead Smelting. Contains one trip report and four
memos on emissions calculations. Maintained by the Pollutant
Assessment Branch, Strategies and Air Standards Division, Office of Air
Quality Planning and Standards, U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina. 1984.
5.
Paul, Robert B. The Glover Lead Smelter and Refinery of the American
Smelting and Refining Company/Glover, Missouri. In: AIME World
Symposium on the Mining and Metallurgy of Lead and Zinc. Proceedings.
St. Louis, Missouri. 1970. p. 738-776.
Emmel, B. and A. J. Miles. (Radian Corporation.) Evaluation of Lead
Emissions Controls at ASARCO's Primary Lead Smelter at Glover,
Missouri. Draft Report. Prepared for U. S. Environmental Protection
Agency. Kansas City, Missouri. September 12, 1984. 59 p.
6.
7.
Beilstein, D. H. The Herculaneum Lead Smelter of St. Joe Minerals
Corporation. In: AIM! World Symposium of the Mining and Metallurgy of
Lead and Zinc. Proceedings. St. Louis, Missouri. 1970. p. 702-736.
8.
Memo from M. Davenport, U. S. Environmental Protection Agency, to file.
July 22, 1980. 6 p. Particulate and Lead Stack Test at ASARCO Lead
Smelter, East Helena, Montana on September 20-29, 1979.
9.
10.
Kelly, W. R. ASARCO in EI Paso.
182:79-98. September 1981.
Cassady, M. E. (OSHA), M. O. Varner (ASARCO), and M. Wright (USWA).
Engineering Assessment and Proposed Compliance Plan for ASARCO's
Primary Lead Smelter, Glover, Missouri. Signed January 30, 1984.
Engineering and Mining Journal.
11.
Cassady, M. E. (OSHA), M. O. Varner (ASARCO), and M. Wright (USWA).
Engineering Assessment and Proposed Compliance Plan for ASARCO's East
Helena Primary Lead Smelter, East Helena, Montana. Signed March 19,
1982, updated January 23, 1984.
37
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12.
Cassady, M. E. (OSHA), M. O. Varner (ASARCO), and M. Wright (USWA).
Engineering Assessment and Proposed Compliance Plan for ASARCO's El
Paso Copper, Lead, and Zinc Smelter, El Paso, Texas. Signed
January 30, 1984.
13.
Midwest Research Institute. Sample Fugitive Lead Emissions from Two
Primary Lead Smelters. Prepared for U. S. Environmental Protection
Agency. Research Triangle Park, N. C. Publication No.
EPA-450/3-77-031. October 1977. III p.
38
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4.0
PRIMARY ZINC SMELTING
This chapter discusses the primary zinc smelting industry and its
associated cadmium. emissions. Section 4.1 presents a brief source category
description. Section 4.2 describes basic production processes and
identifies cadmium emissions sources. Section 4.3 discusses the existing
emission control techniques at primary zinc smelters. Cadmium emissions
estimates are presented in Section 4.4, and Section 4.5 presents a
discussion of EBC options and potential emissions reductions which could be
achieved by the application of EBC. The information presented in this
chapter is based on three trip reports and on the available literature.
4.1
SOURCE CATEGORY DESCRIPTION
There were five primary zinc smelters operating in the United States in
1984. Total zinc slab production in 1983 was 236,000 Mg (260,000 tons),
which accounted for 29 percent of the domestic demand for zinc in that year.
In the past 5 years, zinc slab production at primary smelters fell from
471,000 Mg/yr (521,000 tons/yr) in 1979 ~o 228,000 Mg/yr (252,000 tons/yr)
in 1982. Production increased slightly in 1983 and should continue to
increase in 1984. The ASARCO/Corpus Christi smelter, which was shut down in
1982 and 1983, reopened in 1984.1 The locations and production capacities
of the five operational zinc smelters are shown in Table 4-1. In early
2-6
1984, these were operating near 100 percent capacity. A sixth primary
zinc smelter, the Bunker Hill smelter in Kellogg, Idaho, is shut down and
has not announced plans to reopen.
All of the primary zinc smelters except St. Joe/Monaca also produce
cadmium. Processes and emissions from these cadmium plants are described in
the chapter on primary cadmium smelters (Chapter 2). All information
discussed in this chapter pertains only to the zinc smelting portion of the
co-located zinc and cadmium plants.
39
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TABLE 4-1.
THE DOMESTIC PRIMARY ZINC SMELTERS
Production Capacitya.
Plant Location Mg/yr (tons/yr)
ASARCO/Corpus Christi Corpus Christi, Texas 98,000 (110,000)
AMAX/Sauget Sauget, Illinois 72,000 (80,000)
Jersey Miniere Zinc Clarksville, Tennessee 82,000 (90,000)
National Zinc Bartlesville, Oklahoma 51,000 (56,000)
St. Joe/Monaca Monaca, Pennsylvania 90,000b (lOO,OOO)b
~
o
a
Capacity figures listed in terms of zinc produced per year.
b .
This includes 72,000 Mg/yr (80,000 tons/yr) of zinc and 18,000 Mg/yr
zinc equivalent of zinc oxide.
(20,000 tons/yr)
-------
The ASARCO/Corpus Christi and AMAX/Sauget smelters are both located on
flat terrain near large cities (Corpus Christi, Texas and St. Louis,
Missouri, respectively). The Jersey Miniere Zinc and National Zinc plants
are located on gently rolling terrain near cities with populations of about
30,000. The St. Joe zinc smelter is located in a hilly, sparsely populated
area north of Pittsburgh.
4.2
PROCESS DESCRIPTION
There are two major types of domestic primary zinc metal production
facilities, electrothermic smelters and electrolytic plants. The only
domestic electrothermic primary zinc metal smelter in operation is the
St. Joe Minerals electrothermic smelter in Monaca, Pennsylvania. During the
last few decades, electrolytic zinc plants have achieved predominance over
electrothermic zinc smelters in the domestic primary zinc industry.
The materials processed by the domestic primary zinc industry are
predominantly zinc sulfide ore concentrates. The most common zinc-bearing
constituent of these ores is sphalerite (ZnS). Raw zinc ores are treated at
the mine site with flotation techniques to produce a concentrate containing
up to 62 percent zinc and 32 percent sulfur. Other zinc ore constituents
include iron, calcium, silicon, lead, magnesium, cadmium, copper, aluminum,
cobalt, and arsenic. The cadmium content of the ore concentrates processed
in the domestic zinc smelting industry range from about 0.1 to 4.0 percent
by weight, with the majority of the processed ore containing less than
2-7
0.8 percent cadmium. Ore storage and handling are sources of cadmium
emissions at both electrolytic and electrothermic zinc plants.
4.2.1
Electrolytic Zinc Production
The roasting operation and the remaining steps in the production of
zinc metal at a typical electrolytic zinc smelter are shown in Figure 4-1.
41
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Zinc
Ore
Concentrate
Air
Zinc
Metal
Fl u i'd
Bed
Roaster
Calcine
Sulfuric
Acid
Electrolytic
Ce11 House
Figure 4-1.
ESP
Pre-Cleaned Roaster
Offgas To Acid Plant
Circuit
Cyclone
Manganese
Dioxide
Leach Tank
Zinc
Dust
Cold
Purification
Reactor
Zinc
Dust
Purification
Reactor
Hot
Purification
Reactor
Zinc
Dust
Iron
Cake
Copper
Cake
Cadmium
Cake
Cobalt
Cake
A typical electrolytic zinc smelter.
42
-------
Roasting
The first step in the production of zinc metal from ore concentrates at
both electrolytic and electrothermic zinc smelters is the roasting
operation. Zinc roasting consists of heating the ore concentrates to
650-1,000oC (1,200-1,800°F) in an oxidizing environment. The roast is
carried out below the melting temperature of the charge and has three
primary functions: (i) elimination of sulfur as S02' (ii) conversion of zinc
sulfide to impure zinc oxide, and (iii) removal of volatile impurities from
the ore concentrate. The degree of sulfur elimination accomplished in a
8
zinc roaster varies from about 93 to 97 percent.
The fluid bed roaster is the newest roasting system for zinc sulfide
concentrates and is currently the only type in use. The offgas stream from
a fluid bed zinc roaster typically has an S02 concentration of 10 to
13 percent, and up to 85 percent of the roaster product (calcine) is carried
out with the offgas. Waste heat boilers, cyclones, and electrostatic
precipitators are used in series to capture the entrained portion of the
calcine. At electrolytic zinc plants the collected materials are normally
combined with the remaining portion of the calcine and sent to a leaching
plant.
Leaching and Purification
The roaster calcine is first leached in a dilute sulfuric acid solution
to dissolve the impure zinc oxide. Manganese dioxide (Mn02) is generally
added to the leach tank to cause the precipitation of an iron cake that
contains iron and significant amounts of arsenic, antimony, and silicic
acid. The leachate is then sent to a series of cold and hot purification
tanks where cadmium, copper, and cobalt are removed from solution. The
precipitation reactions that occur are induced by the addition of zinc d~st,
+2 +2 +2
which reduces Cd , Cu , and Co to their respective metallic forms.
The precipitated cadmium is recovered at all four electrolytic smelters
and sold as cadmium metal or cadmium oxide. Processes and emissions from
these cadmium plants are described in Chapter 2, on primary cadmium
smelting.
43
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Electrodeposition
The final step in the electrolytic production of zinc metal is
e1ectrodeposition of zinc onto the surface of the electrodes in an
e1ectro1yti~ cell house. An electric potential is applied to the solution,
,
causing the formation of zinc metal andsu1fur1c acid. The sulfuric acid is
recycled to the leach tank, and the zinc metal is stripped from the
electrodes and cast into slabs.
Emissions Sources
The fluid bed roaster S02 emissions at each of the four domestic
electrolytic zinc smelters are controlled by a contact sulfuric acid plant.
The gas prec1eaning equipment associated with the acid plant effectively
removes cadmium, so actual cadmium emissions from this source are
negligible. The remaining steps in the electrolytic production of zinc do
not generate significant amounts of atmospheric emissions because they are
wet processes. Demisters are used to control acid mist from the cell house
2-7
operations.
Potential fugitive cadmium emissions sources at electrolytic zinc
plants include ore unloading, storage, and handling, and leach residue
storage and handling. Re-entrained road dust is also a potential cadmium
emissions source. There i8 a low potential for process fugitive cadmium
emissions from electrolytic zinc plants. Nearly all of the cadmium is
removed from the circuit by wet precipitation. Zinc melting and casting
operations are the major fugitive particulate emissions sources, but there
is very little cadmium present in the metal. All operations are performed
in enclosed buildings.
4.2.2
Electrothermic Zinc Production
Roasting and Sintering
The roasting operation and the remaining steps in the produ~tion of
zinc metal at the St. Joe/Monaca electrothermic zinc smelter are shown in
Figure 4-2.
Initially ore is dried and the dryer is a potential source of
44
-------
Zinc Ore
Concentrate
~
VI
Air
Reactor Offgas To
Acid P1ant Circuit
F1uid
Bed
Roaster
Figure 4-2.
Sinter
Machine
Offgas
Ca1cine
Exhaust To
Atmosphere
Baghouse
Sinter
Machines (3)
Sinter Fume
Cd and Zn
CO Used
As Fuel
Gases
Sintered
Ca1cine
Electrothel"llic
Sme1ting
Furnaces (4)
Cd/Zn A110y
Electrothermic zinc smelting at the St. Joe/Monaca, Pennsylvania plant.
Recyc1ed
S1ag
S1 ag To
Residue Treatment
Zinc
Oxide
C01
linc
Zinc
Oxide
-------
cadmium emissions.
The ore is then roasted in a fluid bed roaster.
Roasting operations are identical to those described in the 'previous section
on electrolytic zinc plants. Roaster emissions are controlled with an acid
plant preceded by an ESP and a scrubber. The roaster calcine is mixed and
I
pelletized with sand, return sinter fines, coke breeze,and smelting furnace
residue. The pelletized mixture is distributed on grate-type pallets that
move along a continuous metal conveyor system within the sinter machine.
The purpose of the sintering operation is to remove residual sulfur and
volatile impurities such as lead, cadmium, and arsenic from the calcine, and
to agglomerate the feed for reduction in the electrothermic smelting
furnace.
The sinter plant is the primary removal mechanism for cadmium in the
circuit. Fume collected from the sinter plant baghouse at St. Joe contains
7 percent cadmium. Atmospheric emissions from this baghouse would contain a
similar level of cadmium. The collected fume is water-leached to remove
chlorides, and the leach residue is partially recycled. Most of the leach
residue is stored wet in a concrete lined pond.
Electrothermic Furnace Operations
The sinter product is sent to the electrothermic furnace, where the
zinc content of the zinc oxide/coke/silica mixture is separated and reduced
to pure zinc metal which contains only 0.05 percent cadmium. Heat is
produced within the furnace by the resistance of the charge material to the
current flow between pairs of graphite electrodes. The zinc metal produced
is vaporized in the high temperature atmosphere of the furnace [1,400°C
(2,600°F)]. Furnace vapors are drawn through a water cooled, U-shaped
condenser and bubbled through a molten zinc bath. The zinc metal vapor
condenses and is subsequently cast into slabs. Offgases from the
electrothermic furnace are treated with a condenser and scrubber. The
carbon monoxide-containing scrubber offgases are used as fuel or flared,
uncondensed zinc, or "blue powder," is recovered from the scrubbers by
settling the water slurry in ponds.
The solids which contain 75 to
46
-------
80 percent zinc and about 0.14 weight percent cadmium are dried, briquetted,
and recycled to the furnace feed.5 The electrothermic furnaces are a minor
source of cadmium emissions.
Zinc Oxide Production
About 20 percent of the zinc produced by this process is not cast, but
is further refined to produce zinc oxide. The cadmium column generates a
cadmium/zinc alloy (3 weight percent cadmium) that is recycled back to the
electrothermic furnaces. Offgases from the cadmium removal column and the
zinc refinery pass through two fabric filters. The refined zinc is then
burned under controlled conditions to produce zinc oxide. The zinc oxide
product is then collected in large baghouses. These processes are potential
sources of cadmium emissions.
Fugitive Emissions Sources
Fugitive cadmium emissions sources at the St. Joe electrothermic
smelter include storage of the zinc ore concentrate, blue powder, and sinter
fume leach residue; materials conveying and handling; and process fugitives
from the dryer roaster, sinter machine, and electrothermic furnace
buildings. Dust reentrainment from plant roads is another potential
5
fugitive emissions source.
4.3
EXISTING CONTROLS
4.3.1
Controls at Electrolytic Zinc Plants
Table 4-2 lists cadmium emissions sources and current controls in the
primary zinc smelting source category.
Roasting
The roasting operations are po~ential emission sources at all zinc
smelters, but all four electrolytic smelters have sulfuric acid plants and
the associated gas pre-cleaning equipment controlling this source. The
47
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TABLE 4-2.
CADMIUM EMISSIONS SOURCES AND EXISTING CONTROLS IN THE
PRIMARY ZINC SMELTING SOURCE CATEGORY
Emissibn Source
I
Existing Controls
Electrolytic Zinc Smelters
Roasters
Acid plants with gas pre-cleaning
equipment
Process Fugitive Sources
Including Roaster Calcine
Processing
Baghouses, scrubbers
Ore Unloading, Storage, and
Handling Fugitive Emissions
Ore storage bUildings, baghouses,
some outside uncontrolled storage,
enclosed conveying, wet
suppression, road cleaning
Electrothermic Zinc Smelter
Ore Dryer
Venturi scrubber
Roaster
Acid plant with gas pre-cleaning
equipment
Sinter Machine
Baghouse
Electrothermic Furnaces
Condenser and scrubber in series
Cadmium Removal Column
Baghouse
Zinc Refinery
Baghouse
Zinc Oxide Production
Baghouse
Process Fugitives from
Sinter Building
Baghouses
.
Process Fugitives from
Electrothermic Furnaces
Enclosed in a building
Materials Storage, Conveying
Storage buildings, some outside
storage, enclosure of conveyors
and transfer points with
ventilation to baghouses, street
sweeping
48
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roaster offgases are cleaned using cyclones, dry ESP's, wet scrubbers, and
wet ESP's in series before entering the acid plant, and these controls
result in highl~ effective cadmium removal.3-6,9
Minor Point Sources
There are a variety of minor point emission sources at the electrolytic
zinc plants. Individual smelters have up to about 20 small baghouses or
scrubbers controlling a variety of operations such as roaster calcine
469
processing. " In general, process cadmium emissions from electrolytic
plants are low and are well controlled.
FURitive Controls
Ore unloading, storage, and handling are the major fugitive emissions
sources at electrolytic zinc smelters. Detailed information on fugitive
sources and controls are available for three of the four electro~ytic zinc
smelters: Jersey Miniere Zinc, AMAX/Sauget, and ASARCO/Corpus Christi. At
Jersey Miniere Zinc the ore concentrate is unloaded from a barge using a
clamshell and dumped into a feed bin. The baghouse on the feed bin is not
usually used because the material is wet. Spillage of zinc ore around the
bin was noted during a plant visit, but the area is generally cleaned
following unloading. A conveyor belt is used to transport the ore one-half
mile to the plant. The conveyor belt is covered and equipped with a
turnover device to ensure that there is no loss of the ore, but the belt is
not totally enclosed. The ore concentrates are stored in a building
equipped with baghouses. There is no outside ore storage. This is the most
well controlled ore storage operation in the industry. The zinc ore is
blended inside the storage plant and transported to the roasting plant on a
covered conveyor. From that point on, materials are processed wet or are
4
enclosed so fugitive emissions would be very low.
At AMAX/Sauget, ore is stored on outside storage piles. The material
is generally moist, but in warm dry weather, fugitive emissions could result
from load-in and load-out, wind erosion, and vehicular traffic around the
Piles.3
49
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At ASARCO/Corpus Christi, materials arrive by rail, barges, or ships.
Materials arriving by barge or ship are unloaded at the port of Corpus
Christi and transported to the smelter by railcar. Materials are then
unloaded into:hoppers by tractor shovels, and then transported by belt
I 6
conveyor to storage bins which are enclosed in a building. The level of
control on the unloading and conveying operations at ASARCO/Corpus Christi
is unknown.
No information is available on fugitive emission sources or controls at
the National Zinc smelter.
4.3.2
Controls at the Electrothermic Zinc Smelter
Point Sources
As previously noted, the roaster at the St. Joe electrothermic zinc
smelter is controlled with an acid plant and the assoc~ated gas pre-cleaning
equipment. Sinter machines are another major point source of cadmium
emissions and are controlled by a baghouse. Gases from the ore concentrate
dryer are controlled by a venturi scrubber. Emissions from the
electrothermic furnaces (mainly process fugitives) are controlled with a
condenser followed by a scrubber. The carbon monoxide-containing scrubber
offgases are used as fuel or flared. Offgases from the cadmium removal
column and zinc refinery pass through two baghouses. Some of the refined
zinc is then burned under controlled conditions to produce zinc oxide, which
5
is collected in large baghouses.
Fugitive Sources
Potential fugitive cadmium emissions sources at the St. Joe smelter are
as follows: the raw materials storage building, transfer points, the wastes
.
building, the sinter building, the furnace building, the sinter storage
area, and road areas. Based on observations made during a plant visit,
there is generally a low potential for fugitive cadmium emissions. A large
portion of the raw material used at the smelter, including the zinc ore
concentrates, is stored in buildings. Secondary zinc materials used as feed
50
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are stored outside. but this material is coarse. fairly moist. and low in
cadmium. The majority of process fugitive emissions points. are contained
inside buildings. and the material transfer points are covered and vented.
Process fugitive emissions from the sinter building. including emissions
from sizing and crushing operations and from the roaster calcine screw
conveyor system. are controlled by baghouses. There is also a potential for
cadmium emissions from road dust reentrainment. Roads are generally swept;
but during a recent plant visit. there were significant dust accumulations
in places. Roads of concern as cadmium fugitive sources include those
adjacent to the blue powder and leach residue storage areas.5
4.4
EXISTING EMISSIONS
Emissions Calculations for Electrolytic Zinc Plants
Cadmium emissions from the four electrolytic zinc plants are estimated
to be 0.20 Mg/yr (0.22 tons/yr).10 This figure does not include emissions
from co-located cadmium plants which are described in Chapter 2. The
. .
emissions estimate includes ore storage at the four plants. but does not
include unloading at sites away from the main plant (see 'Section 2.2) or
conveying because there are no data on emissions from these operations. The
figure also includes emissions from a calcine processing baghouse at one
plant. This source was tested for particulates. and a cadmium/particulate
ratio was applied to estimate cadmium emissions. It was assumed cadmium
emissions from the acid plants controlling the roasters at all four plants
are negligible because the 'gas pre-cleaning equipment associated with the
acid plant is very effective at cadmium removal.
The methods used to estimate emissions for each plant are described
below. Ore storage emissions for the Jersey Miniere zinc smelter are based
4
on particulate testing of baghouses on the storage building. The
cadmium/particulate ratio of the ore concentrate was then applied to
estimate cadmium emissions. Particulate emissions from the open storage
pile at AMAX/Sauget including load-in. load-out. vehicular traffic, and wind
erosion were calculated by plant personnel using formulas for aggregate
51
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storage piles contained in the U. S. EPA publication entitled "Compilation
of Air Pollutant Emission Factors.,,3 The cadmium/particulate ratio of the
ore was then used to estimate cadmium emissions. There were no data on ore
storage fugit~ve emissions from the other two electrolytic plants.
Emissions from these plants were estimated using the ore storage building
emissions data for the Jersey Miniere smelter and ratioing according to
production capacity and cadmium contents of the ores of the other two
facilities. Ore is stored in buildings at ASARCO/Corpus Christi. but since
it is not known whether storage at National Zinc is completely enclosed. and
storage buildings at both plants probably are not equipped with baghouses,
estimates of fugitive cadmium emissions from ore storage for these plants
may be low. For example, if National Zinc stored its ore in outside piles
rather than in buildings, emissions estimates would increase by about
0.1 Mg/yr (0.11 tons/yr) for the plant.10
Emissions Calculations for the Electrothermal Smelter
Emissions from the St. Joe electrothermic zinc smelter are estimated to
be 3.2 Mg/yr (3.5 tons/yr). This is the estimate provided by plant
personnel for cadmium emissions from the main stack which includes combined
emissions from the acid plant and the sinter
emissions from other point sources described
in comparison to the main stack because the
devices is smaller and the cadmium contents
plant baghouse.
Cadmium
in Section 4.3 would be small
gas flow through other control
of materials and emissions later
in the smelting process are lower than the cadmium content of sinter
5
offgases.
Fugitives from the ore storage building at St. Joe were estimated from
the storage building emissions at Jersey Miniere by ratioing according to
cadmium content of the ores and plant capacities. The emissions estimate is
about .0025 Mg/yr, but this could be low since the St. Joe storage building
is not equipped with baghouses while Jersey Miniere's building is.
Emissions from other fugitive sources at St. Joe (materials handling and
conveying, the wastes building, the sinter building, the furnace building,
52
-------
the sinter storage area, and roads) were not estimated because there are no
data or information from which to develop reliable quantitative estimates.
4.5
ESTIMATED BEST CONTROL (EBC) RECOMMENDATIONS
4.5.1
Recommended EBC
Cadmium EBC for process sources at primary zinc smelters includes
contact sulfuric acid plants and fabric filters. Acid plants and the
associated gas pre-cleaning systems 'are recommended for the treatment of
offgas streams containing sufficient S~2 such as those produced by fluid bed
roasters. The 502 levels of the remaining offgas streams at primary zinc
smelters are too low to make contact sulfuric acid plants a viable EBC
option. Fabric filters are recommended as cadmium EBC for these sources.
Estimated best contrQI for cadmium fugitive emissions in the primary
zinc smelting industry consists of the best available ventilation technology
for each fugitive cadmium emission source followed by particulate removal in
a fabric filter system. This includes enclosure of ore storage areas,
ventilating and/or enclosing material transfer points, properly ventilating
and/or enclosing all furnace operations, and treating all of the ventilation
gas streams with fabric filter systems. The specific techniques
constituting cadmium fugitive EBC will vary from plant to plant due to the
diversity of plant types within the primary zinc smelting industry.
4.5.2
Prevalence of EBC
Table 4-3 summarizes the prevalence of EBC at the five zinc smelters.
Acid plants are in place to control the roaster offgas streams at all five
zinc smelters. This is the only significant process cadmium emission source
at electrolytic zinc smelters, so EBC is in place for process sources at all
four electrolytic smelters. Cadmium EBC is not in place at all fugitive
sources at electrolytic zinc smelters. For example, AMAX/Sauget stores ore
concentrates outside rather than in a building. At Jersey Miniere Zinc, the
53
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TABLE 4-3.
PREVALENCE OF CADMIUM EBC IN THE PRIMARY
ZINC SMELTING SOURCE CATEGORY
Plant
Prevalence of Cadmium EBC
Process Sources Fugitive Sources
All sources at EBC Unknown
All sources at EBC Some sources at EBCa
All sources at EBC Most sources at EBCb
All sources at EBC Unknown
c Most sources at EBCd
Most sources at EBC
ASARCO/Corpus Christi
AMAX/Sauget
Jersey Miniere Zinc
National Zinc
St. Joe/Monaca
aOre is stored outside at AMAX/Sauget. In dry weather fugitive emissions
could result from load-in, load-out, wind erosion, and vehicular traffic
around the storage piles. EBC for this source would be enclosure in a
building.
b .
Ore spillage was noted around the area where zinc ore is unloaded from a
barge. Conveying and ore storage operations, however, are at EBC.
~ajor sources controlled with EBC. However, ore dryer is controlled by a
scrubber and electrothermic furnaces are controlled by a condenser and
scrubber rather than by baghouses.
dElectrothermic furnaces are enclosed in a building with roof monitors.
Process fugitives were visually observed from the top of one furnace,
and such emissions could escape the building. Accumulations of dust were
observed near some storage areas. Other process and area fugitive sources
(materials storage, conveying, and handling and sinter fugitives) are
well controlled.
54
-------
unloading of ore concentrate from the barge is a relatively poorly
controlled operation, although EBC is in place for other fugitive sources at
the plant. There is little information on fugitive controls or the
prevalence of EBC at the other two electrolytic zinc smelters.
Major process sources at the St. Joe electrothermic zinc smelter are
controlled with cadmium EBC. However, the ore dryer is controlled with a
venturi scrubber; the electrothermic furnaces are controlled with a
condenser followed by a scrubber, and the scrubber offgas is flared or used
as fuel. These systems should provide effective cadmium control but may not
be EBC.
Estimated best control is in place at most fugitive sources at the
St. Joe smelter. However, accumulations of dust were noticed on the roads
near some storage areas (see Section 4.4). Also, process fugitives were
visually observed from the top of an electrothermic furnace at St. Joe
during the plant visit.S
4.5.3
EBC Emission Levels
If cadmium EBC were applied to fugitive sources at the four
electrolytic zinc plants, cadmium emissions estimates would be reduced from
0.20 Mg/yr (0.22 tons/yr) to about 0.07 Mg/yr (0.08 tons/yr).lO The
estimated emissions reductions would be the result of enclosing the outside
are storage piles at AMAX/Sauget in a building controlled with a fabric
filter system similar to the storage building at Jersey Miniere Zinc. As
noted previously, data on fugitive emissions and controls are scarce so both
existing and EBC emissions estimates are incomplete.
Since fugitive emissions estimates for the St. Joe smelter are not
available, EBC fugitive emissions estimates for this electrothermic smelter
cannot be made. However, EBC is currently in place at most fugitive
emission points at the St. Joe smelter.
55
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4.6
1.
REFERENCES FOR CHAPTER 4
U. S. Bureau of Mines. Mineral Industry Surveys.
Washington, DC, U. S. Government Printing Office.
Zinc.
June 1984.
2.
Radian Corporation. Preliminary Study of Sources of Inorganic Arsenic.
I
Prepared for U. S. Environmental Protection Agency. Research Triangle
Park, North Carolina. Publication No. EPA-450/5-82-005. August 1982.
p. 58 - 75.
3.
Trip report. Miles, A. J. and L. E. Keller, Radian Corporation, to
file. April 13, 1984. 5 p. Report of visit to AMAX Zinc Company
primary zinc/cadmium plant in Sauget, Illinois.
4.
Trip report. Keller, L. E. and A. J. Miles, Radian Corporation, to
file. April 11, 1984. 10 p. Report of visit to Jersey Miniere Zinc
Company primary zinc/cadmium smelter in Clarksville, Tennessee.
5.
Trip report. Miles, A. J. and L. E. Keller, Radian Corporation, to
file. April 26, 1984. 8 p. Report of visit to St. Joe Resources
Company primary zinc facility in Monaca, Pennsylvania.
6.
ASARCO's Corpus Christi Zinc Plant.
182:99-120. September 1981.
Engineering and Mining Journal
7.
U. S. Bureau of Mines. Occurence and Recovery of Certain Minor Metals
in the Processing of Lead and Zinc. Information Circular 8790.
Washington, DC, U. S. Government Printing Office, 1979.
8.
U. S. Environmental Protection Agency. Background Information for New
Source Performance Standards: Primary Copper, Zinc, and Lead Smelters.
Research Triangle Park, North Carolina. Publication No.
EPA-450/2-74-002a. October 1974.
9.
Letter and attachments from Thorington, M. C., Oklahoma State Air
Quality Service, to Mead, R. C., Radian Corporation. November 29,
1984. 1 p. Information on National Zinc Company's Emissions.
10.
Confidential Files. Zinc and Cadmium Smelting. Contains two trip
reports and four memos on emissions calculations. Maintained by the
Pollutant Assessment Branch, Strategies and Air Standards Division,
Office of Air Quality Planning and Standards, U. S. Environmen~al
Protection Agency. Research Triangle Park, North Carolina. 1984.
56
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5.0
ZINC OXIDE PRODUCTION
This chapter discusses zinc oxide production and its associated cadmium
emissions. Section 5.1 presents a brief source category description.
Section 5.2 describes basic production processes and identifies cadmium
emissions sources. Section 5.3 discusses the existing emission control
techniques at zinc oxide plants. Cadmium emissions estimates are presented
in Section 5.4, and Section 5.5 presents a discussion of EBC options and
potential emissions reductions which could be achieved by the application of
EBC. Information in this chapter is based on two trip reports and on the
available literature.
5.1
SOURCE CATEGORY DESCRIPTION
Domestic production of zinc oxide in 1983 was 130,000 Mg
1
(143,000 tons). Zinc oxide can be produced by the American Process or the
French Process. American Process zinc oxide plants use cadmium-containing
zinc ore concentrates as a raw material, while French Process zinc oxide
plants use high purity zinc metal as a raw material.
There are three American Process zinc oxide plants in the United
States. The locations and production capacities of these plants are shown
in Table 5-1.2,3,4 The ASARCO/Columbus plant is located in a flat,
industrialized area of Columbus, Ohio. The ASARCO/Hillsboro plant is
located in a sparsely populated area near a small town, and the terrain is
fairly level. The New Jersey Zinc plant is located near Palmerton,
Pennsylvania, a town of about 6,000 people, and the topography is hilly.
All three American Process plants were operating near 100 percent capacity
in 1984.2,3,4
There are several French Process zinc oxide smelters in the United
States.
The largest of these is the St. Joe/Monaca zinc smelter described
57
-------
TABLE 5-1.
THE DOMESTIC AMERICAN PROCESS ZINC OXIDE PLANTS
a
Production Capacity
Plant Location Mg!yr (Tons/yr)
ASARCO!Columbus Columbus, Ohio 19,000 (21,000)
ASARCO/Hillsboro Hillsboro, Illinois 9,000 (10,000)
New Jersey Zinc Palmerton, Pennsylvania 30,000 (33,000)
aCapacity figures listed in terms of zinc oxide production.
58
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in Chapter 4.0. As described below, there is little potential for cadmium
emissions from the French Process. Therefore, individual French Process
zinc oxide plants are not considered in this report.
5.2
PROCESS DESCRIPTION
Zinc oxide is produced by two methods in the domestic zinc smelting
industry, the French and American Processes. In the French Process, zinc
oxide is made from the oxidation of purified zinc metal that is volatilized
and oxidized to zinc oxide. This is the type of process used at the St.
Joe/Monaca zinc smelter descTibed in Chapter 4. Cadmium emissions from this
type of zinc oxide facility are expected to be small due to the purity of
the feed material (zinc metal).
American Process zinc oxide is produced directly from zinc ore
concentrates that contain cadmium, and thus has a larger potential for
cadmium emissions. The three domestic American Process zinc oxide smelters
utilize different types of zi~c ore feed materials. ASARCO/Columbus
processes a zinc sulfide ore concentrate, New Jersey Zinc processes a zinc
carbonate ore concentrate, and ASARCO/Hillsboro processes only roasted zinc
ore calcine from ASARCO/Columbus.
Processes at ASARCO Plants
Figure S-1 shows a process flow diagram of the ASARCO/Columbus zinc
oxide plant. The plant uses a zinc sulfide ore concentrate raw material.
The cadmium content of the ore used at ASARCO/Columbus is confidential, but
since the ore contains cadmium, ore unloading, conveying, and storage are
3
potential fugitive cadmium emissions sources at this plant. The first step
in the zinc oxide production process is roasting the zinc ore concentrates
in a fluid bed roaster. Emissions from this source are controlled with an
acid plant and the associated gas pre-cleaning equipment consisting of a
cyclone and an ESP followed by a scrubber. The roaster calcine is conveyed
to an inclined rotary densifying kiln. Emissions from the densifying kiln
contain cadmium and are controlled by a baghouse.
S9
-------
'"
o
Unc
Ore
Conc.n-
tr. t.
Ore
Stor.,.
Stor.,. Or
5111 ppt ngI
£8tssIDIIS
IA portion of the densified cllcine is shipped to ASARCO/Hil1sboro where it is ~rocessed fn
Wetherill Furnlces to produce crude zfnc oxfde.
Call1lus Utili
CIIuobft'
C....
llnc
OxIde
£8hs lOllS
..~
Figure 5-1.
Process flow diagram for the ASARCOjColumbus plant.
-------
A portion of the densified calcine is shipped to the ASARCO/Hillsboro
plant, where it is processed in Wetherill furnaces to produce zinc oxide.
The rest of the densified calcine is processed at ASARCO/Columbus in
Wetherill grate furnaces to produce zinc oxide vapors. Zinc metal vapors
leaving the furnace blocks pass through a combustion chamber and are burned
in air to produce zinc oxide. The vapors are cooled, and zinc oxide is
collected in a bagroom. Exhaust gases containing cadmium are emitted from
the bag room. The crude zinc oxide from the'Wetherill furnace bagroom is
then processed in a rotary refining kiln. Emissions from the rotary kiln
baghouse at ASARCO/Columbus also contain cadmium.2,5
Process fugitive cadmium emission sources at ASARCO/Columbus include
the rotary densifying kiln, Wetherill furnaces, and refining kiln. Area
fugitive emission sources include zinc ore concentrate unloading, storage,
and handling, and baghouse dust handling.
The portion of the densified calcine which is sent from ASARCO/Columbus
to ASARCO/Hillsboro is processed in Wetherill furnaces. The zinc oxide is
then collected in bagrooms, as at ASARCO/Columbus. However,
ASARCO/Hillsboro sells the collected zinc oxide dust without further
refining (i.e., the Hillsboro plant has no refining kilns).
Cadmium emission sources at the Hillsboro plant include the Wetherill
furnace bagroom, process fugitive emissions from the
area fugitive emissions from storage and handling of
2 5
and baghouse dusts. '
Wetherill furnaces, and
the densified calcine
Processes at New Jersey Zinc
New Jersey Zinc/Palmerton processes a low-sulfur zinc ore with a very
4
low cadmium content (0.0036 percent by weight). Because of the low cadmium
content, ore storage and handling would be a minor source of cadmium
emissions.
The zinc oxide production process at New Jersey Zinc/Palmerton is shown
in Figure 5-2. Ore and coal are fed to the Wealz kilns where metals are
volatilized and oxidized. Emissions from the kilns include Wealz oxide (or
crude zinc oxide) and process fugitives, also termed "Wealz fume."
The
61
-------
Wael
Ba
Sinter Machine Fume Kiln Fume Fume
Baghouse Offgas Kiln
Baghouse Baghouse
Offgas
- ".
Sinter Dust Fume Kiln
Waelz Kiln Product Machine
Baghouse Offgas Baghouse
Sinter Machine
Offgas
Calcine
Waelz
z Kiln Fugitive Kiln .
ghouse Offgas Product Waelz Oxide Sinter Machine
Baghouse
4aelz Furnace Product
ugitive~ Baghouse Offgas
aghouse Waelz Kiln Offgas Waelz Sinter
Waelz
Fugitive
Dust
Furnace Furnace
Waelz Kiln Horizontal Grate Product
Furnace Offgas Baghouse
j t
10 Fume
Treatment
0\
N
Ore
Product
Zinc Oxide
Wae 1 z Res idue
Furnace Res ldue
Figure 5-2.
The New Jersey Zinc/Palmerton zinc .'xide plant.
-------
Wealz fume is ducted through a baghouse and then emitted to the atmosphere.
The Wealz oxide is cooled and the crude zinc oxide is collected in a
bagroom. The oxide is then sintered in a downdraft sinter machine to reduce
impuritiess such as leaa and chloride. Sinter emissions are also controlled
with baghouses.
The last step in the process is the final oxidation and purification.
The sinter is mixed with coals and fed to a moving grate furnace. The oxide
is volatilizeds reduced to metallic zincs and then oxidized again. The
purified zinc oxide is then collected in a baghouse.4
The four baghouses mentioned above are the major sources of process
cadmium emissions at New Jersey Zinc/Palmerton. Process fugitive emissions
4
have been observed escaping the hooding that collects the Wealz fume. The
sinter machine and sinter handling are also sources of process fugitive
emissions. Baghouse dust handling is another potential fugitive emissions
source. Additional control of cadmium fugitive and process fugitive
emissions at New Jersey Zinc/Palmerton pote~tially could. be achieved by
making improvements in emissions collection (better hooding or enclosures)
and by giving more attention to control operation and maintenance
procedures.
5.3
EXISTING CONTROLS
Table 5-2 lists potential cadmium emissions sources
controls at zinc oxide production plants. The emissions
plant are described in this section.
and existing
controls at each
ASARCO Plants
Major process sources at ASARCO/Columbus (roaster, densifying kiln,
refining kiln, and Weatherill furnaces) are well controlled. The roaster is
r .
controlled with a contact sulfuric acid plant and associated gas precleaning
equipment necessary for proper acid plant operation. The cyclone, ESP's,
and scrubber used to pre-clean the gas are effective at cadmium removal.
The densifying kiln and refining kiln are controlled with baghouses. The
63
-------
TABLE 5-2.
CADMIUM EMISSIONS SOURCES AND EXISTING CONTROLS
IN THE ZINC OXIDE SOURCE CATEGORY
Emission Source
Existing Controls
Roaster (1 plant)
Acid plant (and associated
cyclones ESPs and scrubber)
Densifying Kiln (1 plant)
Baghouse
Wetherill Furnaces (2 plants)
Baghouses
Refining Kiln (1 plant)
Baghouse
Wealz Kiln Fugitives (1 plant)
Baghouse
Wealz Oxide Collection Bagroom (1 plant)
Sinter Machine (1 plant)
Bagroom
Baghouse
Moving Grate Furnace (1 plant)
Baghouse
Ore Storage and Handling (2 plants)
Open storages Enclosure and
ventilation to baghouses
(2 plants)s Some controls
confidential (1 plant)
Sinter Machine Fugitives (1 plant)
Enclosures Hooding and
baghouses
~'h~"
Sinter Materials Handling (1 plant)
Enclosure, Hooding and
baghouses
Other Fugitives (2 plants)
Confidential (1 plant)
Unknown.(1 plant)
64
-------
Wetherill furnace zinc oxide bagroom is an integral part of the production
process, and also controls cadmium emissions. Zinc oxide packaging
operations and ore handling operations are also controlled by baghouses.2
Information on the control of other fugitive emission sources is available.
but has been declared confidential and is contained in files maintained by
EPA's Pollutant Assessment Branch.3
The only process source of cadmium emissions at ASARCO/Hillsboro is the
Wetherill furnace. Two bag rooms that capture zinc oxide as part of the
production process also control cadmium emissions from this source.5 No
information on fugitive emissions controls at ~he Hillsboro plant are
available.
New Jersey Zinc
The major process cadmium emissions sources at New Jersey Zinc are all
controlled with baghouses. These include the Wealz kiln fugitives (fume)
baghouse. the Wealz oxide bagroom. the sinter baghouse. and the zinc oxide
collection baghouse following the moving grate furnace. Of these, the Wealz
. .
oxide bagroom and zinc oxide baghouse are product collection baghouses while
the other two baghouses are solely for the purpose of controlling
emissions.4
Most process fugitive and area fugitive emissions sources at the New
Jersey Zinc plant are also controlled as detailed below. Ore arriving at
the plant is allowed to "weather" which reduces the amount of dust generated
during handling. Ore is "weathered" when lime in the material accompanying
the ore reacts and agglomerates the ore material. Ore storage during
"weathering" may be a source of fugitive emissions. but the cadmium content
of the ore is very low. Several small baghouses control the ore preparation
and handling operations. As previously noted, fugitive emissions from the"
Wealz kilns are collected by capture hoods and ducted to a baghouse. During
a plant visit. the capture hoods did not appear to be drawing off emissions
properly. However, according to engineering design calculations. the
4
baghouses and fans do appear to be sized properly. There are numerous
small baghouses in the sinter building to control fugitive emissions from
4
materials handling and sintering operations. In general. there is a low
potential for cadmium fugitive emissions from this plant.
65
-------
5.4
EXISTING EMISSIONS
Total point source cadmium emissions from zinc oxide plants are
3
estimated to be, 2.4 Mg (2.6 tons)/yr. Less than 1 percent of these are
from the New Jersey Zinc plant. This is because the ore used at this plant
has a very low cadmium content, and testing of intermediate materials and
baghouse dusts have shown very low cadmium/particulate ratios.6 No testing
of cadmium emission rates has been conducted at zinc oxide plants, and
particulate emissions tests are not available for several sources that are
difficult to test (e.g., bagrooms).
are described below.
Emission sources included in the estimates for New Jersey Zinc are the
Wealz kiln fugitives baghouse, Wealz oxide bagroom, sinter baghouse, and
moving grate furnace zinc oxide baghouse. Emissions for these sources were
calculated from baghouse exhaust gas flowrates by assuming an outlet
particulate loading of 0.005 gr/dscf from the baghouses. This particulate
emissions concentration is typical of properly operated baghouses. The
estimated particulate emissions were then multiplied by cadmium/particulate
ratios obtained from analytical tests on baghouse dusts from the four
baghouses in order to estimate cadmium emissions.3,6
Emissions estimates for ASARCO/Columbus include emissions from the
densifying kiln baghouse, Wetherill furnace bagroom, and refining kiln
baghouse. Particulate emissions estimates made by plant personnel were
multiplied by confidential cadmium/particulate ratios to estimate cadmium
emissions. 3
The basis of the emissions estimates
The only process source of emissions at ASARCO/Hillsboro are the
Wetherill furnace bagrooms. Emissions from Wetherill furnace bagrooms at
Hillsboro were estimated from the cadmium emissions estimates derived for
the ASARCO/Columbus Wetherill bagroom by applying a production ratio for the
3
two plants.
There are no data on fugitive emissions at any of the plants, thus no
reliable cadmium fugitive emissions estimates could be made. However,
process fugitive emissions escaping from kilns were visually observed at two
66
-------
plants, and ore unloading and storage are not well controlled at some
plants, so there may be significant fugitive cadmium emissions from zinc
oxide plants. Discussions of fugitive sources and controls at zinc oxide
smelters are contained in Sections 5.2 and 5.3 and in confidential files.3
5.5
ESTIMATED BEST CONTROL (EBC) RECOMMENDATION
5.5.1
Recommended EBC
Cadmium EBC for point sources at zinc oxide plants includes contact
sulfuric acid plants and baghouses. Acid plants and the associated gas
pre-cleaning systems are recommended for the treatment of offgases
containing sufficient 502 such as those produced by fluid bed roasters. The
cyclone, ESP's, and scrubber used in series to pre-clean the gas are
effective at cadmium and particulate removal. The 802 concentrations of the
remaining offgas streams at American Process zinc oxide plants are too low
. to make contact sulfuric acid plants a viable EBC option. Baghouses are
recommended as EBC for offgas streams low in 802 content. Operations
controlled in this manner include the densifying and refining kilns at
ASARCO/Columbus, the Wetherill furnaces at ASARCO/Columbus and
ASARCO/Hillsboro, and the four major point sources at New Jersey
Zinc/Palmerton (the Wealz kiln fugitives, Wealz oxide offgas, sinter
machine, and horizontal moving grate furnace).
Cadmium EBC for fugitive emissions in the primary zinc oxide smelting
industry consists of the best available ventilation technology for each
fugitive cadmium emission source followed by particulate removal in a
baghouse. This includes enclosure of ore storage areas, ventilating and/or
enclosing all furnace operations, and treating all of the ventilation gas
streams with bag houses. The specific techniques constituting cadmium
fugitive EBC will vary from plant to plant due to the diversity of plant
types within the American Process zinc oxide smelting industry.
67
-------
5.5.2
Prevalence of EBC
Table 5-3 summarizes the prevalence of EBC at the three American
Process zinc o~ide plants. Cadmium EBC is in place for all major process
I
emissions sources at the three plants. EBC is in place for most fugitive
emission sources at the New Jersey Zinc Palmerton plant. Information on
fugitive controls at ASARCo/Columbus is confidentia1,3 and there is no
information on fugitive controls at ASARCo/Hil1sboro at this time.
Therefore, the prevalence of fugitive emission EBC at these two plants
cannot be addressed in this report.
5.5.3
EBC Emission Levels
Since only major process sources at the three zinc oxide plants were
included in the estimate of existing cadmium emissions, and these sources
are already at EBC, the existing cadmium emissions estimate of 2.4 Mg/yr
(2.6 tons/yr) presented in Section 5.4 would also be applicable to.EBC
emissions. Application of EBC to fugitive sources would result in some
cadmium emissions reduction; however, since existing fugitive cadmium
emissions cannot be quantified, the magnitude of emissions reductions under
EBC is unknown.
68
-------
TABLE 5-3.
PREVALENCE OF CADMIUM EBC IN THE
ZINC OXIDE SOURCE CATEGORY
Prevalence of Cadmium EBC
Plant
Process Sources
Fugitive Sources
ASARCO/Columbus
New Jersey Zinc/Palmerton
All sources at EBC
All sources at EBC
All sources at EBC
Confidential
ASARCO/Hillsboro
Unknown
Most sources at EBCa
~ost fugitive cadmium emission sources are well controlled; however, there
is some outside materials storage, and process fugitive emissions were
observ~d escaping from collection hoods at the Wealz kilns during one plant
visit. See Sections 5.4 and 5.5 for a description of fugitive sources and
controls.
69
-------
5.6
REFERENCES FOR CHAPTER 5
1.
U. S. Bureau of Mines. Mineral Industry Surveys. Zinc.
Washington. D. C.. U. S. Government Printing Office.
June 1984.
2.
Radian Cor~oration. Preliminary Study of Sources of Inorganic Arsenic.
Prepared for U. S. Environmental Protection Agency. Research Triangle
Park. N. C. Publication No. EPA-450/S-82-00S. August 1982. p. 70,
78.
3.
Confidential files. Zinc and Cadmium Smelting. Contains two trip
reports and four memos on emissions calculations. Maintained by the
Pollutant Assessment Branch, Strategies and Air Standards Division,
Office of Air Quality Planning and Standards, U. S. Environmental
Protection Agency, Research Triangle Park, NC. 1984.
4.
Trip report. Miles, A. J. and J. H. E. Stelling, Radian Corporation,
to file. February 25, 1983. Report of visit to New Jersey Zinc
Company, Inc. in Palmerton, Pennsylvania.
s.
Telecon. Dennis, P., Illinois Division of Air Pollution Control, with
R. C. Mead, Radian Corporation. November 9, 1984. Stack parameters
for ASARCO/Hillsboro and AMAX/Sauget.
6.
Test Results. Report to U. S. Environmental Protection Agency.
Prepared by Radian Analytical Services. Cadmium content New Jersey
Zinc samples.
70
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6.0
SEWAGE SLUDGE INCINERATION
This chapter describes sewage sludge incineration processes and their
associated cadmium emissions. Section 6.1 presents a brief characterization
of the source category. Section 6.2 describes the major technologies
employed to incinerate sewage sludge and identifies cadmium emissions
sources. Section 6.3 discusses the control techniques currently in place at
sewage sludge incinerators. Cadmium emissions estimates are presented in
Section 6.4, and Section 6.5 discusses EBC options and the potential
emissions reductions achievable by the application of EBC.
6.1
SOURCE CATEGORY DESCRIPTION
,
The sewage sludge incineration source category includes incineration
units that are used to dispose of residues or sludges generated during the
treatment of wastewater in municipal sewage treatment plants. Cadmium is a
trace component of sewage treatment sludge, and thus can be volatilized and
emitted when sludge is incinerated for disposal purposes. The cadmium
content of sewage sludge is highly variable from treatment plant to
treatment plant and within the same plant. Two recent studies of several
sludge samples from different treatment plants produced cadmium in sludge
ranges of 0 - 1,100 mg/kg (dry sludge basis) and 3 - 3,410 mg/kg (dry sludge
1 2
basis).' In an associated EPA study on priority pollutants from
publically owned treatment works (POTW's), the cadmium content of sludge
within a single treatment plant was found to vary from 4 - 145 percent from
the mean content.3
Currently in the United States, there are about 33,000 POTW's producing
sludge that eventually requires disposal. In 1982 these 33,000 plants had
an actual wastewater input load of approximately 102,206 million liters/day
4-6
(MLD) [27,000 million gallons/day (MGD)]. Approximately 17 percent of
71
-------
this input quantity or 17,129 MLD (4,525 MGD) entered POTW's that are
capable of incinerating all or part of the sludge generated" in treating the
wastewater. These data indicate that only a small portion of the total
number of POTW's:have incinerators associated with them.
I
No precise data are available on the amount of sludge incinerated
annually in the United States; however, the U. S. EPA Sludge Task Force has
estimated that 6.3 million dry Mg (7 million dry tons) of sludge are
produced annually by all POTW's in the country.6 Of this total, the Task
Force estimates that between 15 and 22 percent is disposed of through
incineration. On this basis, the total amount of sludge incinerated
annually is between 0.99 and 1.35 million dry Mg (1.1 and 1.5 million dry
tons).
This estimate can be confirmed on the basis of the amount of wastewater
entering plants that employ incineration as a disposal technique. The
corresponding flow of wastewaters into the incineration facilities listed in
the EPA Sludge Task Force survey is 17,129 MLD (4,525 MGD). Although the
. ) . .
amount of sludge generated per gallon of wastewater treated can vary greatly
as a function of the specific treatment processes employed, an average value
of 0.59 dry Mg (0.65 dry tons) of sludge per million liters (gallons) of
7
wastewater was derived from 35 POTW's that employ incineration. Applying
this value to the estimated wastewater in-flow determined by the Sludge Task
Force, yields about 0.99 million dry Mg (1.1 million dry tons) of sludge
incinerated annually.
Since it is not known precisely how much of the
treatment plants that are equipped with incinerators
in this manner, the lower end of the range estimated
tons/year) is considered the most reliable.
Although the amount of sludge incinerated in the U. S. is roughly,
known, there is no exact quantification of the number of individual sewage
sludge incinerators currently in operation. The two primary sources of
information on the number and location of sludge incinerators are the NEEDS
survey,5 conducted biennially by the U. S. EPA in compliance with
Sections 205(a) and 516(b)(2) of the Clean Water Act, and incineration
sludge generated at
is actually disposed of
above (1.1 million
72
-------
facility surveys conducted by EPA's Sludge Task Force. The latest work by
the Sludge Task Force estimates that as of July 1983, approximately
175 POTW's are incinerating all or part of the sludge they generate. The
Task Force data base does not indicate the number or description
(incinerator design, emission controls, etc.) of individual incinerators at
each POTW. The list of POTW's thought to contain sewage sludge incinerators
is presented in Table 6-1. The largest concentrations of units are found in
the Midwestern and Great Lakes States as illustrated in Figure 6-1. Sludge
incinerators are generally located in urban areas at POTW's that are
relatively long distances from land or ocean disposal sites, or where
regulations prohibit these alternative disposal methods. It is estimated
that there are on average two sludge incinerators per POTW site or roughly
350 in the country. However, many sites have only one incinerator, while
others such as Indianapolis, Detroit, and St. Paul operate as many as 8 -
10 units.
A variety of different technologies are available for incineration of
municipal sewage sludge. By far the most common is the multiple-hearth
furnace (MHF). Of the 176 incineration plants listed in Table 6-1, 132
(75 percent) employ multiple-hearth incinerators. Fluidized-bed furnaces
(FBF) account for most of the additional incinerators currently operating in
the U. S. Table 6-1 lists 28 treatment plants that employ fluidized-bed
incinerators (about 16 percent of the total). Electric (infrared)
incinerators are also sometimes used for disposing of sewage sludge,
particularly in smaller rural communities. Eight electric sewage sludge
incinerators have been identified to currently be in operation. Also, one
facility uses a rotary kiln incinerator to dispose of sewage sludge. These
individual incinerator types and their associated emissions are discussed in
detail in Section 6.2.
73
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TABLE 6-1.
LOCATIONS OF WASTEWATER TREATMENT PLANTS USING SEWAGE SLUDGE INCINERATORS
c a
Incinerator Location PON Name Wastewater Flow. MLD (MGD)
Multiple-Hearth Units
Anchorage. Alaska BO Point Woronzof STP 90.85 (24.00)
Palo Alto. California Palg Alto WWTF 98.42 (26.00)
San Mateo NIA 45.42 (12.00)
South Lake Tahoe South Tahoe WWTF 21.20 (5.60)
Truckee Tahoe-Truckee WWTF 16.28 (4.30)
Martinez NIA 113.56 (30.00)
Redwood City NA 72.68 (19.20)
...... Cromwell. Connecticut MDC WPCF 70.41 (18.60
.&:-- Hartford Hartford WPCF 180.56 (47.70)
New Haven East Shore WPCF 33.31 (8.80)
New Haven Boulevard WPCF 46.94 (12.40)
New London New London WPCF 12.08 (3.19)
Waterbury Waterbury WPCF 84.64 (22.36)
Wil1imantic Willimantic WPCF 9.73 (2.57)
Pensacola. Florida Main Street Plant 31.15 (8.23)
Atlanta. Georgia Area R. M. Clayton 317.97 (84.00)
Atlanta. Georgia Area Utoy Creek NIA
Cobb County Chattahoochee 64.35 (l7.00)
Savannah President Street WPCF 66.36 (17.53)
Marietta N/A N/A
Honolulu. Hawaii Sand Island WWTF 236.59 (62.50)
Honolulu Honolulu WWTP 94.64 (25.00)
Oahu N/A N/A
-------
TABLE 6-1.
LOCATIONS OF WASTEWATER TREATMENT PLANTS USING SEWAGE SLUDGE INCINERATORS
(Continued) .
c
Incinerator Location
POTW Name
a
Wastewater Flow, MLD (MGD)
Decatur, Illinois
Rock Falls
Rockford
Decatur STP
Rock Falls STP
Rockford S.D. STP
94.64
7.23
147.86
East Chicago, Indiana
Indianapolis
East Chicago STP
Belmont Street Plant
56.78 (15.00)
473.18 (125.00)
Cedar Rapids, Iowa
Davenport
Cedar Rapids WPCF
Davenport WWTP
93.88
73 .06
.....
V1
Johnson County, Kansas
132.49
Mission Township STP .
(Main Sewer District No.1)
Turkey Creek MSD 01
Shawnee Mission
23.24
Kenton County, Kentucky
N/A
Algiers, Louisiana
Lake Charles
Lake Charles
New Orleans W. Bank STP
Plant C
Plant B
46.56
10.98
7.57
Annapolis, Maryland
Riviera Beach
Annapolis City STP
Cox Creek WWTP
15.10
20.90
Attleboro, Massachusetts
Chicopee
Fitchburg
Lawrence
New Bedford
Quincy
Worcester
Attleboro WWTW
Chicopee WWTP
Fitchburg East WWTP
Greater Lawrence SD WWTP
New Bedford WWTP
Nut Island WWTP,
Upper Blackstone Reg WWTP
13.67
17.98
19.61
145.40
148.01
483.59
122.27
(25.00)
0.91)
(39.06)
(24.80)
(19.30)
(35.00)
(6.14)
N/A
(12.30)
(2.90)
(2.00)
(3.99)
(7.90)
(3.61 )
(4.75)
(5.18)
(38.41)
(39.10)
(127.75)
(32.30)
-------
TABLE 6-1.
LOCATIONS OF WASTEWATER TREATMENT PLANTS USING SEWAGE SLUDGE INCINERATORS
(Continued)
Incinerator Locationc
POTW Name
Wastewater Flow, MLD (MGD)a
.....
0\
Ann Arbor, Michigan
Ann Arbor
Bay City
Bay County
Battle Creek
Detroit
East Lansing
Grand Rapids
Kalamazoo
Lansing
Niles
Owosso
Pontiac
Trenton, Michigan
Wayne County
Eagan, Minnesota
St. Paul
St. Louis, Missouri
St. Louis
Zephyr Cove, Nevada
Lebanon, New Hampshire
Merrimack
Manchester
Ypsi Community WWTP
Ann Arbor WWTP
Bay City STP
Bay County STP
N/A
Detroit STP
East Lansing WWP
Grand Rapids
Kalamazoo QQTP
Lansing WWTP
Niles Wastewater Treat PL
Owosso WWTP
Pontiac STP
38.76
61.70
43.76
44.29
(10.24)
(16.30)
(11.56)
(11.70)
N/A
(698.00)
(11.00)
(50.00)
(33.00)
(28.00)
(3.60)
(2.92)
(20.00)
(5.60)
(45.30)
39.14 (10.34)
764.65 (202.00)
529.96 (140.00)
416.40 (110.00)
(1.00)
(1. 27)
(2.33)
(26.00)
2,642.22
41. 64
189.27
124.92
105.99
13.63
11.05
75.71
Trenton WWTP
Wyandotte STP
21.20
171.48
Seneca Treatment Plant
Metropolitan TP
Bissell Point STP
Lemay STP
Douglas Co SID ~1 WWTF
3.79
Lebanon WWTF
Merrimack WWTP
Manchester WWTP
4.81
8.82
98.42
-------
TABLE 6-1.
LOCATIONS OF WASTEWATER TREATMENT PLANTS USING SEWAGE SLUDGE INCINERATORS
(Continued)
c
Incinerator Location
POTWName
a
Wastewater Flow. MLD (MGD)
Atlantic City. New Jersey
Jersey City
Parsippany-Troy Hills
Princeton
Wayne Township
Atlantic County SA
West Side STP
Rockaway Val Regn S A TRT
Stony Brook RSA STP 81
Mountain View STP
80.55
132.49
27.41
16.66
90.85
.....
.....
Amherst. New York
Beacon
Buffalo
Dunkirk,
Greece
Mamaroneck
New Rochelle
Orangeburg
Oswego
Oswego
Port Chester
Rochester
Rochester
Schenectady
Southampton
Tonawanda
Wheatfield
N/A
Beacon WPCP
Birds Island STP
Dunkirk STP
N W Quadrant TP
Mamaroneck San. Sew. Dist.
New Rochelle SD STP
Orange town DPW
East STP
West
Port Chester SD STP
Gates Chili'Ogden STP
Frank E. Van Lare WWTP
Schenectady STP
Disposal District No. 15
Two Mile Creek SD Plant 2
Niagara CO SD 81 STP
14.98
676.19
22.83
42.32
57.92
61. 70
27.25
11.36
15.14
27.25
40.88
261.19
54.06
113.56
54.24
53.00
Greensboro. North Carolina
Rocky Mount
North Buffalo WTP
Rocky Mount WWTP
35.96
39.67
(21. 28)
(35.00)
(7.24)
(4.40)
(24.00)
N/A
(3.93)
(178.63)
(6.03)
(11.18)
(15.30)
(16.30)
(7.20)
(3.00)
(4.00)
(7. 20)
(10.80)
(69.00)
(14.28)
(30.00)
(14.33)
04.00)
(9.50)
(10.48)
-------
TABLE 6-1. LOCATIONS OF WASTEWATER TREATMENT PLANTS USING SEWAGE SLUDGE INCINERATORS
(Continued)
c POTW Name a
Incinerator Location Wastewater Flow, MLD (MGD)
Akron, Ohio Akron WWTP 298.86 (78.95)
Canton Canton WWTP 124.92 (33.00)
Cincinnati Millcreek WWTP 405.04 (107.00)
Cincinnati Little Miami WWTP 143.85 (38.00)
Cleveland Westerly WWTP 189.27 (50.00)
Cleveland Southerly WWTP 416.40 (1l0.00)
Columbus Jackson Pike WTP 348.26 (92.00)
Euclid Euclid WWTP 63.97 (16.90)
Youngstown Youngstown WWTP 109.78 (29.00)
..... Tigard, Oregon Durham Regional STP 29.15 (7.70)
co
Amhridge, Pennsylvania Ambridge STP 4.54 (1.20)
Apollo Kiski Valley WPCA 10.41 (2.75)
Bridgeport Bridgeport STP 2.04 (0.54)
Chester Delcora Chester STP 134 .38 (35.50)
Colmar Hatfield Township STP 7.84 (2.07)
Johnstown City of Johnstown 27.07 (7.15)
Norristown E Norristowu Polymouth TP 19.68 (5.20)
Old Forge Lower Lackawanna STP 21.20 (5.60)
Pittsburgh Alcosan WWTP 757.08 (200.00)
Wilkes-Barre Wyoming Valley San Auth 94.26 (24.90)
Willow Grove Upper Moreland-Hatboro TP 16.85 (4.45)
Lemoine Borough Cumberland City 33.84 (8.94)
Cranston, Rhode Island Cranston WPCF 34.83 (9.20)
-------
TABLE 6-1.
LOCATIONS OF WASTEWATER TREATMENT PLANTS USING SEWAGE SLUDGE INCINERATORS
(Continued)
c POTW Name a
Incinerator Location Wastewater Flow, MLD (MGD)
Charleston, South Carolina Plum Island TRT Plant 55.08 (14.55)
Columbia Metropolitan TRT Plant 84.04 (22.20)
Maryville, Tennessee Maryville Regional STP 11.51 (3.04)
Nashville Nashville Central WWTP 193.43 (51.10)
Alexandria, Virginia Alexandria STP 95.77 (25.30)
Arlington Arlington Co WPCP 85.55 (22.60)
Fairfax Lower Potomac STP 87.33 (23.07)
Newport News Boat Harbor WPCF 69.92 (18.47)
Norfolk Lamberts Point WPCF 104.33 (27.56)
...., Norfolk Army Base WPCF 52.92 (13.98)
\0
Virginia Beach Chesapeake-Elizabeth WPCF 96.15 (25.40)
Williamsburg Williamsburg WPCF 21.61 (5.71)
Woodbridge Potomac River STP 76.69 (20.26)
Clarksburg, West Virginia Clarksburg STP 17.34 (4.58)
Brookfield, Wisconsin Brookfield STP 37.85 (10.00)
Green Bay Green Bay WWTP 108 . 11 (28.56)
Milwaukee South Shore Waste Water TP 272.17 (71.90)
Fluidized-Bed Units
North Little Rock, Arkansas Faulkner Lake STP 21.20 (5.60)
San Bernardino San Bernardino WWTP 82 54.02 (14.27)
South Bayside
Redwood City S. Bayside WWTP . 72.68 (19.20)
-------
TABLE 6-1.
LOCATIONS OF WASTEWATER TREATMENT PLANTS USING SEWAGE SLUDGE INCINERATORS
(Continued)
c
Incinerator Location
POTWName
a
Wastewater Flow. MI.D (MGD)
Stratford. Connecticut
Elkart. Indiana
Dubuque. Iowa
Kansas City. Kansas.
Kansas City
New Orleans. Louisiana
00
o
Ocean City. Maryland
Lynn. Massachusetts
Port Huron. Michigan
Duluth. Minnesota
Independence. Missouri
Omaha. Nebraska
Somerset-Raritan.
Two Bridges
Union Beach
Waldwick
West Bedford
New Jersey
Stratford WPCF
30.28
(8.00)
(17 .20)
(9.35)
(85.00)
(20.00)
(70.60)
(6.95)
N/A
(14.50)
(27.82)
N/A
(30.00)
(15.00)
(70.00)
(10.00)
(8. 00)
(20.00)
Elkart WWTF
65.11
Dubuque WWTP
35.39
N/A
KCK WWTP 11 - KAW Point
321. 76
75.71
New Orleans East Bank
267.25
Ocean City WWTP
26.31
Lynn Regional WPCP
Port Huron STP
54.89
WLSSD Regional WWTF
105.31
N/A
Papillion Creek
113.56
N/A
Fairfield
N/A
N/A
N/A
Sewer Authority
56.78
264.98
37.85
30.28
75.71
-------
TABLE 6-1.
LOCATIONS OF WASTEWATER TREATMENT PLANTS USING SEWAGE SLUDGE INCINERATORS
(Continued)
c POTW Name a
Incinerator Location Wastewater Flow, MLD (MGD)
Hamburg, New York Southtowns STP 60.57 (16.00)
Port Washington Port Wahington STP 12.76 (3.37)
Poughkeepsie Arlington SD 11.36 (3.00)
Shelby, North Carolina N/A 14.61 (3.86)
Hazelton, Pennsylvania Hazelton STP 21.96 (5.80)
King of Prussia Trout Run WPC 15.52 (4.10)
Clarksville, Tennessee Clarksville Main WWTP 17.30 (4.57)
00
~ Edmonds, Washington Edmonds STP 17.03 (4.50)
Electric Units
Decatur, Georgia Snapfinger WWTP 151. 42 (40.00)
Gainesville Flat Creek WPCP 53.00 (14.00)
Cynthiana, Kentucky N/A 13.25 (3.50)
Bay County, Michigan N/A 121.13 (32.00)
Sylvan Beach, New York East Oneida Lake WPCP 6.62 (1.75)
Fayetteville, North Carolina Cross Creek Plant 60.57 (16.00)
Greenville, Texas Greenville SPT 22.56 (5.96)
Aberdeen, Washington Aberdeen STP 18.17 (4.80)
-------
TABLE 6-1.
LOCATIONS OF WASTEWATER TREATMENT PLANTS USING SEWAGE SLUDGE INCINERATORS
(Continued)
c
Incinerator Location
PON Name
a
Wastewater Flow, HLD (MGD)
Rotary Kiln Units
Lake Arrowhead, California
Lake Arrowhead WWTF
3.03
(0.80)
Combination Sludge/Municipal Waste Units
New Canaan, Connecticut New Canaan WPCF 5.30 (1.40)
Stamford Stamford WPCF 73.44 (19.40)
Glen Cove, New York Glen Cove STP 21.58 (5.70)
c;o
t-:I Other Sludge Units
Rockville, Connecticut Vernon WPCF 8.93 (2.36)
Lyons, Kansas Lyons STP 2.20 (0.58)
St. Charles, Missouri St. Charles Miss. River STP 7.57 (2.00)
Meadow Grove, Nebraska Meadow Grove WWTP 0.23 (0.06)
aMLD equals million liters per day and MGD equals million gallons per day.
bN/A means information not availble.
c
The estimated total number of sludge incinerator locations in 176.
-------
00
lAJ
Number of Plants per State
II
~
D
10 or more
5 or more
less than 5 ( includes Alaska and Hawaii)
Figure 6-1.
Location of currently operating sewage sludge incineration facilities
in the continental United States.4
-------
6.2
PROCESS DESCRIPTION
6.2.1
Process Overview
,
The major processes involved in a municipal wastewater treatment plant
include sedimentation. filtration. digestion. chemical conditioning. and
dewatering. From the standpoint of incineration as a sludge disposal
method. the most important aspect of these related treatment processes is
their impact on the moisture and energy content of the sludge. Several of
the processes which reduce the moisture content of wastewater sludge can
also reduce the proportion of volatile elements to inert materials.
Secondary treatment processes. such as anaerobic digestion. can
significantly lower the energy content of the sludge. Most sewage sludges
undergo a variety of individual treatments followed by the final
conditioning and dewatering steps. Dewatering is a critical step in the
process of sludge incineration, since it reduces the. thermal demand on the
incinerators. Vacuum filtration. filter presses. belt filters. and
centifugation are the most widely used sludge dewatering technologies.
although numerous other processes are available.
After dewa~ering. sludge may be incinerated using either
multiple-hearth furnaces. fluidized-bed furnaces. electric incinerators. or
rotary kiln incinerators. The general operation of each of these sludge
disposal devices is described below.
6.2.2
Multiple-Hearth Furnaces
Figure 6-2
Multiple-hearth
The outer shell
illustrates the overall design of a multiple-hearth furnace.
furnaces are cylindrically shaped and oriented vertically.
is constructed of steel and surrounds a series of horizontal
refractory hearths. A hollow cast iron rotating shaft runs through the
center of the hearths. Cooling air is introduced into the shaft by a fan
located at its base. Attached to the central shaft are rabble arms. which
extend above the hearths.
Burners. providing auxilliary fuel. are located
in the sidewalls of the hearths.
84
-------
COOLING AIR DISCHARGE
FLUE GASES OUT
DRYING ZONE
COMBUSTION
AIR RETURN
COOLING ZONE
ASH DISCHARGE
RA BBLE ARM
DRIYE
COOLING AIR FAN
Figure 6-2.
Cross section of a typical multiple-hearth incinerator.
85
-------
The size of MHF's used for incineration of sewage sludge typically
range from six hearth furnaces having an outer diameter of ~ 1.8 m.
(~ 6 ft.) and a total effective hearth area of 7.9 sq. m. (85 sq. ft.), to
12 hearth, 6.7 m.' (22 ft.) diameter furnaces with hearth areas of over
278.7 sq. m. (3,000 sq. ft.).8 Hearth loading rates range from 3.2 to
5.4 kg (7 to 12 lbs) of wet sludge per hour, per square foot. This
corresponds to furnace capacities of from 272 kg (600 lbs) of wet sludge per
hour up to 16.2 Mg (18 tons) per hour.
Partially dewatered sludge is fed into the periphery of the top hearth.
The motion of the rabble arms rakes the sludge toward the center shaft where
it drops through holes located near. the edge of the hearth. In the next
hearth the sludge is raked in the opposite direction. This process is
repeated in all of the subsequent hearths. The effect of the rabble motion
is to break up solid material to allow better surface contact with heat and
oxygen, and is arranged so that a sludge depth of about 1 inch is maintained
in each hearth at the design sludge flow rate.
Ambient air is first ducted through the central shaft and its
associated rabble arms. A portion, or all, of this air is then taken from
the top of the shaft and recirculated into the lowermost hearth as preheated
combustion air. Shaft cooling air which is not circulated back into the
furnace is ducted into the stack downstream of the air pollution control
devices. 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. Provisions are usually made to inject ambient air
directly into one of the middle hearths as well.
From the standpoint of the overall incineration process,
multiple-hearth furnaces can be divided into three zones. The upperhearths
comprise the drying zone where most of the moisture in the sludge is
evaporated. The temperature in the drying zone is typically between 4270 and
760°C (800° and 1,400°F). Combustion occurs in the middle hearths (second
zone) as the temperature is increased to about 927°C (1 ,700°F). The
combustion zone, can be further subdivided into the upper-middle hearths
where the volatile gases and solids are burned, and the lower-middle hearths
86
-------
where most of the fixed carbon is combusted. 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.
Under proper operating conditions, 50 to 100 percent excess air must be
added to a MHF in order to ensure complete combustion of the sludge.
Besides enhancing contact between fuel and oxygen in the furnace, these
relatively high rates of excess air addition are necessary in order to
compensate for normal variations in both the organic characteristics of the
sludge feed and the rate at which it enters the incinerator. When an
inadequate amount of excess air is available, only partial oxidation of the
carbon will occur with a resultant increase in emissions of carbon monoxide,
soot, and hydrocarbons. Too much excess air, on the other hand, can cause
increased entrainment of particulates (including cadmium-containing
particles) and unnecessarily high fuel consumption.
Another important parameter in the operation of a multiple-hearth
sewage sludge incinerator is the rate of feed of the sludge cake. Any
sudden increase or decrease in load to the furnace can severely affect the
performance of the incinerator.9 A sharp increase in the rate of feed has
been shown to lower the combustion zone in the furnace. This can
subsequently lead to a decrease in temperature within the combustion zone
and the potential for the fire to be extinguished. Conversely, a sudden
decrease in furnace load can cause excessively high temperatures in the
furnace with the attendant risk of damage to the refractories and rabble
castings. The moisture content of the sludge feed must also be kept
relatively constant for the same reasons.
The speed at which the rabble arms are rotated can also have a critical
impact on the operation of a multiple-hearth incinerator. Typically, the
rotational speed can be varied between 0 and 3 revolutions per minute. As
the speed of the rabble mechanism is increased, the rate of drying in the
upper hearths is increased and the combustion zone temperatures tend to
rise. Combustion will also tend to take place in a greater number of
hearths. Experimental data have also demonstrated that the temperature of
the hottest hearth will decrease as the speed of the rabble arm rotation is
87
-------
10
increased. The opposite effects are observed when the speed of the rabble
motion is decreased. The speed of the rabble movement should be set slow
enough to form good furrows in the sludge, but fast enough to avoid crusting
of the sludge in Fhe upper hearths. The optimum speed is a function of the
sludge moisture content and loading rate.
For optimum performance, the temperature profile within the furnace
should be controlled by adjusting the firing rate of. the burners. Ideally,
only those burners located immediately above and below the combustion zone
should be used (depending on the number of hearths, and the capacities of
the available burners). This allows a greater sludge residence time in the
drying zone and can decrease turbulence in the upper hearths.
Theoretically, combustion can become self sustaining in a MHF when
sludges having a heating value of at least 23.3 MJ/kg (10,000 Btu/lb), a
moisture content of less than 75 percent, and a volatile solids fraction of
at least 60 to 65 percent are incinerated. However, under autogenous
conditions the highest temperature in the furnace may only be about 482°C
(900°F), which is insufficient to completely destroy odor causing
11
organics. Even at minimum excess air rates, some auxilliary fuel must be
burned in MHF's in order to maintain a minimum temperature of 732°C
(1,350°F) for destruction of odoriferous materials.8
As discussed above, the operation of multiple-hearth sludge
incinerators is complicated by the number of process variables involved, as
well as by the transient nature of some of the responses observed when these
variables are altered. The Indianapolis Center for Advanced Research
(ICFAR) has established guidelines for the operation of multiple-hearth
12
furnaces based on theoretical and empirical research. Although the best
mode of operating any incinerator is a function of numerous site-specific
conditions, a number of general procedures have been established as the.
result of the ICFAR work. These operational guidelines include:
(1) Utilization of shaft cooling air as combustion air;
(2) Maintenance of sludge combustion on the lower burning hearths;
(3) Use of only those burners located on, or immediately adjacent to,
the combustion hearth(s);
88
-------
(4)
(5)
(6)
Maintenance of rabble arm speed as slow as possible;
Minimization of air leakage into the incinerator;'
Maintenance of sludge loading rates at, or below, design
and;
capacity,
(7) Maintenance of excess air at 25 to 50 percent.
At incinerators where these procedures have been put into practice, fuel
savings of from 30 to 70 percent have been attained.9,12 Moreover, there
are some indications that the operational procedures which result in
reductions in fuel use also result in decreased emissions of particu1ates.12
6.2.3
Fluidized-Bed Incinerators
Figure 6-3 depicts the cross-section of a fluidized-bed sludge
incinerator. Like multiple-hearth furnaces, fluidized-bed furnaces (FBF)
are cylindrically shaped and oriented vertically. The outer shell is
constructed of steel and is lined with refractory. Tuyeres are located at
the base of the furnace within a refractory lined grid. A bed of sand,
approximately 0.76 m. (2.5 ft.) thick, rests upon the grid.
Two general configurations can be distinguished on the basis of how the
fluidizing air is injected into the furnace. In the hot windbox design the
air is first passed through a heat exchanger where heat is recovered from
the hot flue gases. Alternatively, ambient air can be injected directly
into the furnace.
The physical dimensions of FBF units range from diameters of 1.8 to
7.6 m. (6 to 25 ft.). The corresponding range in the freeboard area is 2.8
to 48.8 sq. m. (30 to 525 sq. ft.). Fluidized-bed incinerators have sludge
loading rates of between 146.5 to 292.9 wet kg/hr/sq.m. (30 to 60 wet
1b/hr/sq. ft.) (roughly 5 times higher than multiple-hearth furnaces).
Burning capacities of FBF units range from 0.45 to 13.5 Mg (0.5 to 15 tons)
of wet sludge per hour.
Partially dewatered sludge is fed into the lower portion of the
furnace. Air injected through the tuyeres at pressures of from 3 to 5 psig,
simultaneously fluidizes the bed of hot sand and the incoming sludge.
89
-------
Exh8u.t
Sand Ie.."
Fluidized
.and
Figure 6-3.
Cross-section of a fluidized-bed sewage sludge
incinerator.
90
-------
Temperatures of 760° to 927°C (1,400° to l,700°F) are maintained in the bed.
Residence times are on the order of 2 to 5 seconds. As the. sludge burns,
fine ash particles are carried out the top of the furnace. Some sand is
also removed in the air stream; sand make-up requirements are on the order
of 5 percent for every 300 hours of operation.
The overall process of combustion of the s~udge occurs in two zones.
Within the bed itself (Zone 1) evaporation of the water and pyrolysis of the
organic materials occur nearly simultaneously as the temperature of the
sludge is rapidly raised. In the second zone (freeboard area), the
remaining free carbon and combustible gases are burned. The second zone
functions essentially as an after-burner.13
From the standpoint of combustion, fluidization of the sludge has a
number of advantages. First, the turbulence in the bed facilitates the
transfer of heat from the hot sand particles to the sludge. Similarly,
nearly ideal mixing is achieved between the sludge and the combustion air as
a result of the greatly increased surface areas available. Finally, the
sand provides a relatively uniform source of heat within the bed.
The most noticeable impact of the better burning atmosphere provided by
a fluidized-bed incinerator is seen in the amount of excess air required for
complete combustion of the sludge. Fluidized-bed sludge incinerators can
achieve complete combustion with 20 to 50 percent excess air. This is about
half the amount of excess air typically required for incinerating sewage
sludge in multiple-hearth furnaces. As a consequence, FBF incinerators have
4
generally lower fuel requirements compared to MHF incinerators.
Controlling the rate of feed of the sludge into the incinerator is the
most critical operating variable. There is an upper limit on the rate of
heat transfer that can be achieved for a given quantity of sand. If the
rate of sludge feed exceeds the burning capacity of the sand bed, combustion
will not be complete. Similarly, either a rapid increase in the overall
furnace load or in the total moisture content of the sludge will lead to
coagulation of the sludge into heavy masses, depress the bed, and halt
combustion. It is also important, for the same reasons, to ensure that an
adequate residence time is available for the sludge to burn completely.
91
-------
However. due to their excellent mixing characteristics. as well as their
short residence times. fluidized-bed sludge incinerators are less vulnerable
than MaF's to flu~tuations in the rate of sludge. and total moisture input
into the furnace. I Moreover. any disruption of combustion will occur almost
immediately. and can be more easily detected and corrected by the operators
of the furnace.4
Available test data on scrubber-controlled fluidized-bed sewage sludge
incinerators indicates that cadmium emissions increase as the incinerator
bed temperature is increased. In tests of one incinerator. raising the
temperature from 704°C (1.3000F) to 927°C (1.700°F) increased cadmium
14
emissions by 81 times. Single data points on nine other scrubber-
controlled FBF's operated at bed temperatures ranging from about 704°C
(1.300°F) to 925° (1.697°F) showed cadmium emissions. as a function of the
cadmium content of the sludge. increasing from 0.1 percent up to 40 percent
1
at the higher temperature levels. Given the volatility and enrichment
1 14
behavior of cadmium. these results would be expected. .
6.2.4
Electric Incinerators
The electric furnace is the newest of the technologies currently in
commercial use for the incineration of sewage sludge. Most of these units
were installed in the middle and late 1970's. The capacities of eXisting
units are less than 1 ton of wet sludge per hour.
Electric incinerators consist of a horizontally oriented. insulated
furnace. A belt conveyor extends the length of the furnace. 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
pre-fabricated modules. which can be 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 1 inch thick across the width of the belt. The sludge is
92
-------
dried and then burns as it moves beneath the infrared heating elements.
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. Exhaust
gases leave the furnace at the feed end.4
Ash
6.2.5
Other Incinerator Designs
A number of other technologies have been used for the incineration of
sewage sludge including cyclonic reactors, rotary kilns, and wet oxidation
reactors. With the exception of one currently operating rotary kiln, these
types of incinerators are no longer in use. Rotary kilns have limited
sludge handling capacities of approximately 544 kg/hr (~ 1,200 lb/hr). The
kiln is inclined slightly to the horizontal plane, with the upper end
receiving both the sludge feed and the combustion air. A burner is located
at the opposite end of the kiln. The kiln rotates at a speed of about
15.2 em. (6 in.) per second. Ash. is deposited into a hopper located below
the burner.4
6.2.6
Cadmium Emissions Enrichment Behavior
At the combustion temperatures of sewage sludge incinerators, the
majority or all of the cadmium present in the sludge is volatilized since
the boiling point of cadmium is 765°C (1,4100F). Once volatilized, eventual
emissions of cadmium from an incinerator depend on whether the cadmium
condenses in the bottom ash, in relatively larger fly ash, or in the finer
fly ash. Work by Bennett and Knapp and others has demonstrated that cadmium
emissions from sewage sludge incineration are enriched in fine particles to
1 15
a large extent.' In tests of three multiple-hearth incinerators and one
fluidized-bed incinerator, controlled cadmium emissions were found to be
enriched an average of 31-fold as opposed to the cadmium concentrations
found in the sludge feeds. The average mass median particle diameter of the
93
-------
controlled cadmium emissions ranged from 0.28 to 1.1 microns. Very few
cadmium-containing emissions were greater than 2 microns in.diameter. In
tests of one of the multiple-hearth units, 72 percent of uncontrolled
cadmium emissions ~ere less than 1 micron in diameter. IS
These data indicate that cadmium is enriched in fine particles when
emitted from sewage sludge incineration. This behavior must be considered
when evaluating cadmium emissions control. The control of cadmium-
containing particles less than 1 micron in diameter is going to be poor with
existing scrubbers that have been designed to remove general particulate
matter with relatively large particle sizes.
6.3
EXISTING CONTROLS
Particulate emissions from sewage sludge incinerators have historically
been controlled by wet scrubbers. The most obvious reasons for this are
that a sewage treatment plant provides a relatively inexpensive source of
scrubber water (plant effluent is used) and a system for treatment of the
scrubber effluent is available (spent scrubber water is fed to the head of
the treatment plant for solids removal). In addition, a long history of
scrubber applications has demonstrated success in meeting pollution control
standards for particulate matter.4 The primary forces currently having some
regulatory effect on cadmium emissions from sewage sludge incinerators are
the Federal new source performance standard (NSPS) for sewage sludge
incinerators (currently under EPA review) and State and local regulations
pertaining to sludge incinerators. Twenty-two States have adopted the NSPS
for regulating emissions from new sewage sludge incinerators. The remaining
States either have sewage sludge incinerator standards that are less strict
than the NSPS limits or have only general incineration standards that do.not
4 6
apply directly to sewage sludge units. '
Multiple-hearth and fluidized-bed incinerators that have begun
operating over the past 5 years commonly employ combination venturi/
94
-------
impingement-tray scrubbers to control particulate emissions. In most cases.
these scrubbers are operated at total pressure drops of approximately
4
30 inches water gauge. Over the past 10 years there has been a distinct
trend toward the nearly exclusive use of combination venturi/impingement-
tray scrubbers to control emissions from multiple-hearth incinerators.
Prior to 1978 only about 20 percent of multiple-hearth incinerators were
equipped with venturi/impingement-tray scrubbers. All but three of the
17 multiple-hearth incinerators installed after 1978 utilize this
technology. however. Three of the four new fluidized-bed incinerators are
also equipped with combination venturi/impingement-tray control devices.
Although all electric incinerators installed since 1978 utilize a venturi.
only one of these is followed by an impingement-tray scrubber.4
The average pressure drop for all scrubbers installed after 1978 is
approximately 25 inches water gauge. This is higher than the average
pressure drop of 19 inches water gauge for the control devices in use when
the NSPS was reviewed in 1978. The trend toward increasing pressure drops
for scrubbers applied to sludge incinerators reflects the wide variability
in the amount of particulates that potentially may enter the scrubber.
rather than widespread difficulties in meeting the NSPS.
6.3.1
Control Technologies Applied Prior to 1978
Table 6-2 shows the estimated distribution of emission controls applied
to sludge incinerators prior to 1978. As Table 6-2 indicates. a wide
variety of emission controls were applied to all types of incinerators prior
to 1978. The types of controls shown in Table 6-2 range from low pressure
drop spray towers and wet cyclones (pressure drops from 4 to 9 inches water
gauge). to higher pressure drop venturi scrubbers and venturi/impingement-
tray scrubbers (pressure drops from 12 to 40 inches water gauge). In
general. the lowest pressure drop scrubbers were utilized prior to proposal
of the NSPS in the early 1970's. The most widely used type of control
device applied to multiple-hearth incinerators was the impingement-tray
95
-------
TABLE 6-2.
DISTRIBUTION OF EMISSION CDNTROL TECHNOL?9IES APPLIED TO SELECTED
SEWAGE SLUDGE INCINERATORS PRIOR TO 1978
Range of
Applications to Incinerators Pressure Drops
Control Type Total Number Percent of Total (inches water gauge)
Multiple-Hearth Incinerators
Impingement-Tray 21 40 6 - 9
Venturi 12 22 15 - 32
Venturi/Impingement-Tray 11 20 15 - 35
Spray Tower 4 10 4 - 9
Wet Cyclone 3 5 3 - 4
\0 Venturi/Wet Cyclone 2 3 15
0'\ Total 53
Fluidized-Bed Incinerators
Venturi/Impingement-Tray 15 68 12 - 40
Impingement-Tray 5 23 4
Venturi 2 9 17 - 18
Total 22
Electric Incinerators
Venturi 4 57 4 - 9
Impingement-Tray 2 29 6 - 9
Venturi/Wet Cyclobe 1 14 12
Total 7
-------
scrubber. Combination venturi/impingement-tray scrubbers were most widely
applied to fluidized-bed incinerators. Most electric incinerators used
venturi scrubbers.4
6.3.2
Control Technologies Applied After 1978
Table 6-3 shows the distribution of emission control technologies
applied to'sewage sludge inci~erators built since 1978. The majority of the
sewage sludge incinerators installed since 1978 are equipped with
venturi/impingement-tray scrubbers. Before 1978, only 20 percent of the
multiple-hearth incinerators used venturi/impingement-tray scrubbers, but
after 1978, this number increased to nearly 90 percent. Three of the four
new fluidized-bed incinerators are also equipped with combination
venturi/impingement-tray scrubbers. New electric incinerators are
controlled predominantly by individual venturi scrubbers.4
Pressure drops for the venturi/impingement scrubbers shown in Table 6-3
rang~ from 10 to 45 inches water gauge. In general, this represents an
increase in pressure drop over the same type of scrubber used prior to 1978.
6.3.3
Control Device Performance in Cadmium Emissions
The data base from which to characterize the effectiveness of existing
scrubber control systems on cadmium emissions from sludge incinerators is
ver.y limited. Given the small particle enrichment behavior exhibited by
sludge incinerator cadmium emissions, it is expected that control devices
designed primarily to reduce general particulate emissions would be
ineffective at controlling cadmium-containing particles with diameters of
1 micron or less. This theory is somewhat refuted by the data shown in
Table 6-4, which were developed from actual source tests of five MHF's and a
FBF. These data indicate that good cadmium control performance can be
achieved with relatively low pressure drop scrubber systems.
The average cadmium control efficiency for the six sewage sludge
incinerators tested was about 83 percent. The percent removals ranged from
54 percent with an impingement-tray scrubber to 99 percent with a
97
-------
TABLE 6-3.
DISTRIBUTION OF EMISSION CONTROL TECHNOLOGIES APPLIED
TO SEWAGE SLUDGE INCINERATORS AFTER 1978 .
Control Type
Total Number Percent of Total
Range of
Pressure Drops
(inches water gauge)
Multiple-Hearth Incinerators
Venturi/Impingement-Tray
Fabric Filter
Impingement-Tray
Total
15
1
1
17
88
6
6
10 - 45
10
Fluidized-Bed Incinerators
Venturi/Impingement-Tray
Venturi
Total
3
1
~
75
25
42
N/Aa
Electric Incinerators
Venturi
Venturi/Impingement-Tray
Total
3
1
-r
75
25
8 - 10
10
a
Not available.
98
-------
TABLE 6-4.
CONTROL EFFICIENCIES FOR CADMIUM EMISSIONS FROM SEWAGE SLUDGE INCINERATORS18
Control Revice Pressure Drop c
Incinerator Removal Efficiencies (%)
Incinerator Type a Type (inches W.G.) Particulate Cadmium
MERL A MHF I 10 98.69 54.41
MERL C MHF I 16 90.61 85.38
MERL D MHF I 6 98.73 89.99
MERL E MHF V-I 20 93.78 74.49
MERL F MHF V-I 20 93.82 93.98
\0 MERL J FBF V-I 16 99.70 99.01
\0
Average 15 95.89 82.88
~F = Multiple-hearth furnace; FBF = Fluidized-bed furnace.
bI = Impingement-tray scrubber; V-I = Venturi/impingement-tray scrubber.
c
The percent reduction results are questionable because the control device inlet and outlet
sampling measurements taken during testing of these incinerators were not made simultaneously.
-------
venturi/impingement-tray scrubber.lS The results reported for incinerator
MERL F appear to be faulty in that a higher cadmium remova1'as opposed to
general particulate emission removal would not be expected regardless of the
control device use~ given cadmium's enrichment behavior.
The data reported in Table 6-4 are absolute numbers taken from actual
source tests; however, their usefulness in accurately evaluating the control
performance of scrubbers on sludge incinerator cadmium emissions is
questionable. The percent reduction results for cadmium and general
particulate emissions are questionable because the control device inlet and
outlet sampling measurements taken during testing were not made
simultaneously. For this reason, the percent reductions reported in
Table 6-4 do not necessarily represent the true reductions being achieved at
the point in time the measurements were made. Given the variability of
cadmium levels in sludge and the associated change in cadmium emissions
potentially occurring, non-simultaneous measurements may significantly
affect the percent emission reductions that are predicted to be achievable.
6.4
EXISTING EMISSIONS
The basis or starting point for estimating existing cadmium emissions
from sewage sludge incinerators is the total quantity of sludge that is
incinerated annually in the United States. As stated in Section 6.1, this
quantity is 0.99 million dry Mg (1.1 million dry tons)/yr for all of the
estimated 300 to 350 sewage sludge incinerators. The quantity of sludge
incinerated determines the quantity of cadmium that is available to be
emitted to the air from this source category. Even though the cadmium
content of sludge is highly variable, typical or predominantly occurring
concentrations can be determi.ed and multiplied by the quantity of sludge
incinerated to determine total potential uncontrolled cadmium emissions.
These steps were followed in this project to estimate total potential
uncontrolled cadmium emissions ;rom sewage sludge incineration. The typical
2
level of cadmium found in sludge was assumed to be 104 mg/dry kg. This
level is the average cadmium concentration in sludge for 16 American cities
100
-------
analyzed over a 1 year period. The calculation procedure to determine the
amount of cadmium available for emission is as follows.
9
(0.99 x 10 kg) x 104 mg/kg
-
102.96 Mg of potential cadmium emissions
Due to emission controls and deposition in bottom ash, not all of the
approximately 103 Mg (114 tons) of potential cadmium emissions are released
to the air from sewage sludge incinerators. Based on approximately
35 source tests of MHF's and FBF's, the average percentage of cadmium
emitted to the air from sludge incinerators, as a function of the amount of
1 2
cadmium in the sludge, is about 10 percent.' From all the tests, the
fraction of cadmium emitted ranged from 0.03 to 60 percent. This highly
variable range of emission rates is a function of (1) the variability in the
quality of the sludge, (2) the manner in which the incinerator is ope~ated,
i.e., excess air rates used, operating temperatures maintained, residence
times provided, supplemental fuel required, and (3) the control device used
and how it is operated.
The estimated existing level of cadmium emissions nationwide from
sewage sludge incinerators is 10.3 Mg (11.4 tons)/yr [0.10 x 103 Mg
(114 tons)]. Incinerator-by-incinerator emission estimates cannot be
provided because the number, size, and control status of individual sewage
sludge incinerators is not known.
6.5
ESTIMATED BEST CONTROL (EBC) RECOMMENDATION
The selection of a recommended EBC for this source category is based
largely on the results of EPA's recently ~ompleted, detailed assessment of
sewage sludge incinerators for the purposes of reviewing and possibly
revising the previously promulgated NSPS for sludge incinerators. The NSPS
review indicated that from the standpoints of applicability, performance,
and usage in the industry, high pressure drop venturi/impingement-tray
scrubbers appear to be the optimum particulate emission control system for
4
sludge incinerators. As discussed in Section 6.3 and shown in Table 6-3,
101
-------
76 percent of the sewage sludge incinerators installed since 1978 use
venturi/impingement-tray scrubbers for emissions control. Since no other
applicable control system (whether in use or not) is viewed as having an
equivalent genera~ particulate emission removal capability or superior fine
particle emission removal capability, venturi/impingement-tray scrubbers are
recommended as a reasonable EBC for cadmium emissions from sewage sludge
incinerators. Based on the sewage sludge NSPS review work, venturi/impinge-
ment-tray scrubber systems should probably be operated at pressure drops of
at least 25 inches water gauge or greater for the purposes of constituting
4
EBC for cadmium emissions from sludge incinerators. Data are insu~ficient
from which to recommend an emission reduction efficiency for the
venturi/impingement-tray scrubber EBC system. However, it is anticipated
that reductions'of 90 percent or greater are reasonably achievable.
The extent to which this recommended EBC system is in place on sewage
sludge incinerator units installed after 1978 is clearly defined in
Table 6-3. Given the more diverse population of control systems applied to
incinerators installed prior to 1978 (see Table 6-2) and the non-dominance
of venturi/impingement-tray systems on the pre-1978 units where data are
available, it is anticipated that many of the pre-1978 sludge incinerators
do not have the recommended EBC system in place.
6.6
EBC EMISSIONS
After a thorough analysis of the existing sludge incinerator cadmium
emissions information from which EBC emissions possibly could be calculated,
it was determined that there was no sound basis from which to quantitatively
estimate sludge incinerator EBC emissions. The primary reasons for this
conclusion involve sewage sludge incineration source category faftors that
have been explained in previous sections. The more important factors are
summarized as follows.
(1)
There is no available definition of the sizes and emission
controls in place on individual sludge incinerators.
102
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(2)
There are essentially no valid data on the effectiveness of
existing controls at removing sludge incinerator cadmium
emissions.
(3)
The cadmium emission removal performance of the recommended EBC
system is not defined~
Given the above factors, there is no basis from which to establish the
incremental level of cadmium emissions that could be reduced under EBC.
As described in Section 6.5, it is projected that many of the pre-1978
sewage sludge incinerators do not have the recommended EBC system in place
and are not removing cadmium emissions to a level that is equivalent to that
expected of EBC. It is anticipated that the implementation of the
recommended venturi/impingement-tray scrubber EBC system at the pre-1978
units would significantly reduce estimated national cadmium emissions from
sludge incinerators below the 10.3 Mg (11.4 tons)/yr currently existing.
One reason for this expected emissions reduction is that the predominantly
less than EBC equipped pre-1978 incinerators are responsible for over
90 percent of the existing cadmium emissions total for the source category.
The sources constituting the largest quantity of emissions have the greatest
capacity or potential for improved emissions reduction.
W3
-------
6.7
REFERENCES FOR CHAPTER 6
1.
Gerstle, R. W. and D. N. Albrinck. Atmospheric
from Sewage Sludge Incineration. Environmental
32(11):1119-1123. November 1982.
I
Emissions of Metals
Science and Technology.
2.
Hall, R. R., et ale State of New Jersey Incinerator Study, Volume II -
Technical Review and Regulatory Analysis of Sewage Sludge Incineration.
Revised Draft Final Report. Performed under EPA Contract No.
68-02-3168, Work Assignment 16. Prepared for U. S. Environmental
Protection Agency, Research Triangle Park, NC. October 1982.
3.
Variability of Metal Content Within Municipal Sludges - Draft Report.
Booz, Allen, and Hamilton, Inc. Prepared for U. S. Environmental
Protection Agency, Office of Solid Waste, Washington, DC. July 30,
1982.
4.
Second Review of Standards of Performance for Sewage Sludge
Incinerators - Preliminary Draft. Emission Standards and Engineering
Division, Office of Air Quality Planning and Analysis, U. S.
Environmental Protection Agency, Research Triangle Park, NC.
March 1984.
5.
Office of Water Program Operations. The 1982 NEEDS Survey:
Conveyance, Treatment, and Control of Municipal Wastewater, Combined
Sewer Overflows, and Stormwater Runoff. U. S. Environmental Protection
Agency. Publication No. EPA/43019/83-002. Jun~ 1983.
6.
Telecon. R. M. Dykes, Radian Corporation, with J. Smith, Center for
Research Information and Technology Transfer, U. S. Environmental
Protection Agency. January 13, 1983. Source of Sludge Task Force
Survey Data.
7.
Office of Solid Wastes. Environmental Impact Statement. Criteria for
Classification of Solid Waste Disposal Facilities and Practices. U. S.
Environmental Pr~tection Agency, EPA/SW-821, 1979.
Unterberg, W., R. J. Sherwood, and G. R. Schneider. Computerized
Predesign and Costing of Multiple-Hearth Furnace Sewage Sludge
Incinerators. AIChE Symposium Series. ~(129). 1972.
8.
9.
Verdouw, A. J. and E. W. Waltz. Sewage Sludge Incinerator Fuel
Reduction at Nashville, Tennessee. Indianapolis Center for Advanced
Research. U. S. Environmental Protection Agency. Contract
No. 68-02-3487. 1982.
10.
Attman, R. D., et ale Coincineration of Sewage Sludge with Coal or
Wood Chips. Metropolitan Waste Control Commission of St. Paul,
Minnesota. MWCC Project No. 75-05. 1979.
104
-------
11.
Ferrel, J. A. 1973.
1(3). March 1973.
Pollution Engineering.
Sludge Incineration.
12.
Verdouw, A. J., Eugene W. Waltz, and W. Bernhardt. Plant Scale
Demonstration of Sludge Incineration Fuel Reduction. Indianapolis
Center for Advanced Research. U. S. Environmental Protection Agency.
Contract No. S306248010. 1982.
13.
Liao, P. B. Fluidized-Bed Sludge Incinerator Design. Journal of the
Water Pollution Control Federation. 46(8). August 1974.
14.
Trichon, M., et a1. The Fate of Trace Metals in a Fluidized Bed Sewage
Sludge Incinerator. Paper 81-51.3 presented at the 74th Annual Meeting
of the Air Pollution Control Association. 1981.
15.
Bennett, R. L. and K. T. Knapp. Characterization of Particulate
Emissions from Municipal Wastewater Sludge Incinerators. Environmental
Science and Technology. 16(12):831-836. 1982.
16.
Helfand, R. M. A Review of Standards of Performance for New Stationary
Sources - Sewage Sludge Incinerators. EPA-450/3-79-010. March 1979.
p. 3-9.
17.
Shelton, R. and A. Murphy. Particulate Emission Characteristics of
Sewage Sludge Incinerators - NSPS Review. Prepared for Emission
Standards and Engineering Division, Office of Air Quality Planning and
Standards, U. S. Environmental Protection Agency, Research Triangle
Park, NC. Performed under EPA Contract 68-02-3064. March 1980.
18.
Wall, H. and J. B. Farrell. Air Pollution Discharges from Ten Sewage
Sludge Incinerators. Draft Report. Municipal Environmental Research
Laboratory, U. S. Environmental Protection Agency, Cincinnati, Ohio.
February 1981.
105
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7.0
MUNICIPAL WASTE INCINERATION
This chapter discusses municipal waste incineration and its associated
cadmium emissions. Section 7.1 presents a brief source category description.
Section 7.2 describes the basic incineration processes and identifies
factors affecting cadmium emissions. Section 7.3 discusses the existing
control techniques used at municipal waste incinerators. Cadmium emissions
estimates are presented in Section 7.4, and Section 7.5 presents a discussion
of EBC options and the potential emission reduction which could be achieved
by the application of EBC.
7.1
SOURCE CATEGORY DESCRIPTION
The municipal waste incineration source category consists of
approximately 116 installations engaged in high temperature burning
materials for the purposes of volume reduction, and in some cases,
associated heat energy recovery. The wastes burned in muni~ipal incinera-
tion units come primarily from residential sources; however, commercial and
industrial sources can in some areas contribute significant quantities to
the total waste load. Municipal waste incineration is practiced as a
reasonable alternative to the more predominant solid waste disposal method
of landfilling. Incineration is a particularly important and useful waste
of waste
disposal option in space limited areas such as large, densely populated
1 2
metropolitan cities and cities in coastal zones. '
There are two broad categories of incinerators currently used in the
United States to perform municipal waste incineration. For identification
purposes, these two categories are known as conventional incinerators and
modular or package incinerators. The most significant difference between
these categories is the designed waste throughput capacities of typical
units. Conventional incinerators are large units that have throughput rates
106
-------
in excess of 45 Mg (50 tons)/day. Conventional units currently in operation
have waste throughputs as high as 1,800 Mg (2,000 tons)/day~1 Modular units
are designed to be, much smaller in terms of the waste load a single unit can
handle. Modular incineration units generally have waste handling capacities
of less than 45 Mg (50 tons)/day and the majority are less than 27 Mg
(30 tons)/day.1
Large conventional incinerators are generally more applicable in
situations of continuous operation where a large and constant or steady
stream of waste material is generated. Disadvantages to using conventional
incinerators include a long planning and start-up period before actual
operation is realized and a condition of being subject to State and federal
air pollution control regulations (thereby dictating an added cost for
overall incinerator installation and operation).
The increased use of modular incinerators for municipal waste disposal
is a relatively new trend in the United States that has taken place
primarily in the last 5 to 10 years.1,3 A typical, self-contained modular
incinerator unit contains the incinerator itself, refuse handling equipment,
. .
standard utility connections, and if applicable, emission control equipment.
Modular units"are designed to be off-the-shelf incinerators that are easily
and quickly combined with similar self-contained units of the same given
type to enable a facility to increase its waste handling ability without
having to purchase a whole new incineration system. Existing modular
1
incinerator systems contain as many as 8 individual module units. Overall,
modular units are better suited to handling batch waste disposal operations
that are characteristic of sporadic or fluctuating waste material loads.
One added advantage of modular units is that they are generally exempt from
air pollution control regulations.
Currently, there are 57 conventional municipal incineration units known
to be in use in the United States.1,4 The locations of each of these units,
the operational design type of each unit, and the average waste throughput
rates (daily and annual) of each unit are given in Table 7-1. As shown in
Table 7-1, the States of Connecticut, New York, Pennsylvania, Massachusetts,
Florida, Ohio, and Virginia contain the majority of the existing conventional
incinerators.
107
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TABLE 7-1.
1
CONVENTIONAL MUNICIPAL WASTE INCINERATION FACILITIES
Average Waste Average Waste
Incinerator Rate. Rate.
Site Name Location Type Hg (Tons)/Day Hg (Tons)/Year
UNITS WITHOUT HEAT RECOVERY
Ansonia Ansonia. CT Unknown 136 (ISO) 35.360 (38.896)
Stamford Stamford. CT Starved air 145 (160) 41.470 (45.617)
rocking grate
New Canaan New Canaan. CT Starved air 91 (100) 23.660 (26.026)
reciprocating
East Hartford East Hartford. CT Kiln 136 (150) 35.380 (38.918)
..... SWRC 11 Washington. D.C. Train 1.361 (1.500) 353.860 (389.245)
o
GO
Orlando Orlando. FL Starved air 91 (100) 23.660 (26.026)
reciprocating
Dade County Dade County. FL Starved air 218 (240) 56.680 (62.348)
Watpaho Honolulu. HI 3 stage traveling 408 (450) 106.080 (116.688)
grate
East Chicago (Nicosia) East Chicago. IN Starved air 295 (325) 76.700 (84.370)
rocking grate
Louisville Louisville. KY Starved air 771 (850) 280.644 (308.708)
Shreveport Shreveport. LA Water wall 154 (170) 40.040 (44.044)
reciprocating
Baltimore Baltimore. KD Water wall 726 (800) 226.512 (249.163)
-------
TABLE 7-1.
1
CONVENTIONAL MUNICIPAL WASTE INCINERATION FACILITIES (Continued)
Average Vaste Average Vaste
Incinerator late, late,
Site Name Location Type Kg (Tons)/Day Hg (Tons)/Year
Fall River Fall River, MA Starved air 544 (600) 141,440 (155,584)
reciprocating
FraJIinghaJI Fra.ingh.., MA Starved air 181 (200) 47,060 (51,766)
reciprocating
Bridgewater Bridgewater, HA Unknown 272 (300) 70,720 (77,792)
St. Louis (11) St. Louis, HO Starved air 363 (400) 94,380 (103,818)
manual stacked
St. Louis (12) St. Louis, HO Starved air 508 (560) 132,080 (145,288)
-nual stacked
b Crosse Pointa Crosse Pt., HI Unknown 544 (600) (155,584)
\0 141,440
South East Oaklanda Oakland, HI Unknown 544 (600) 141,440 (155,584)
Red Bank Red Bank., NJ Starved air 32 (35) 9,984 (10,982)
reciprocating
Huntington Huntington, NY 3 starved air 272 (300)b 70,720 (77,792)b
units; 2 _nual
stacking;
1 reciprocating
Oyster Bay Oyster Bay, NY Starved air 907 (1,000) 235,820 (259,402)
reciprocating
Tonawanda Tonawanda, NY Starved air 227 (250) 59,020 (64,922)
reciprocating
Lackawanna Lackawanna, NY Starved air 907 (1,000) 235,820 (259,402)
South Brooklyn New York, NY Unknown 907 (1,000) 235,820 (259,402)
-------
TABLE 7-1.
1
CONVENTIONAL MUNICIPAL WASTE INCINERATION FACILITIES (Continued)
Average Waste Average Waste
Incinerator Rate. Rate.
Site NSIIM! Location Type Hg (Tons)/Day Hg (Tons)/Year
Green Point New York. NY Unknown 907 O.OGO) 235.820 (259.402)
NRP Dayton Dayton. OR Unknown 544 (600) 141.440 055.584)
SRP Dayton Dayton. OR Unknown 544 (600) 141.440 (155.584)
Lakewood Lakewood. OR Unknown 150 (165) 39.000 (42.900)
East Central Philadelphia. PA Starved air 635 (700) 231.140 (254.254)
North West Philadelphia. PA Starved air chain 635 (700) 231.140 (254.254)
.... Shippensburg Shippensburg. PA Rotary kiln 65 (72) 16.900 08.590)
.... Webber County. PA 181 (200) (62.119)
o Webber County Starved air 56.472
reciprocating
Newport News Newport News. VA Starved air 272 (300) 99.008 008.909)
reciprocating
Portsmouth Portsmouth. VA Starved air 318 (350) 90.948 000.043)
rolling grate
Sheboygan Sheboygan, WI Water wall raking 136 (150), 35,360 (38,896)
UNITS WITH HEAT RECOVERY
Pinellas County Pinellas County, FL Unknown 1,800 (2,OOO)d 468,000 (520,000)
North West Chicago, IL Starved air 1.451 0,600) 529.615 (582,577)
reciprocating
Baltimore Baltimore, HD Rotating kiln 907 (1,000) 330.148 (363,163) .
Resco Saugus, HA Starved air 1,089 0,200) 397.485 (437.234)
-------
TABLE 7-1.
1
CONVENTIONAL MUNICIPAL WASTE INCINERATION FACILITIES (Continued)
Average Waste Average Waste
Incinerator Rate. Rate.
Site Name Location Type Hg (Tons)/Day Kg (Tons)/Year
Braintree Braintree. !fA Water vall 218 (240) 56.680 (62.348)
Betts New York. NY Unknown 907 0.000) 235.820 (259.402)
Hempstead Hempstead. NY Water vall 1.224 0.350)c 445.536 (490.090)
reciprocating
Westchester County Westchester County. NY Water vall 1.701 0.890)d 442.260 (491.400)
New Hanover County New Hanover County. NC Water wall 180 (200)d 46.800 (52.000)
Akron Akron. OH Stoker grate 810 (900) 210.600 (234.000)
boiler
Columbus Columbus. OH Stoker grate 450 (500) 117.000 (130.000)
.... boiler
....
.... lIarr1sburg Harrisburg. PA Starved air 653 (720) 238.345 (262.180)
reciprocating
Nashville Nashville. TN Starved air 653 (720) 238.345 (262.180)
reciprocating
Gallatin Gallatin. TN Water wall rotary 180 (200)d 46.800 (52.000)
Harrisonburg Harrisonburg. VA Unknown 63 (70) 16.380 (18.200)
Norfolk Navy Norfolk, VA Starved a1r 327 (360) 119.028 (130,931)
Public Works reciprocating
Langley Air Force Hampton, VA Water wall 180 (200) 46,800 (52.000)
Base
Waukesha Waukesha. WI Refractory vall 100 (110) 26.000 (28.600)
reciprocating
aThe use of heat recovery at these units could not be determined.
bTotal waste load for all 3 units.
Cyotal waste load for 2 units. Individual breakdowns are 544 Hg (600 tons) and 680 Hg (750 tons).
dThese rates represent capacity conditions. Average rates vtre not available.
-------
Modular incinerators engaged in municipal waste disposal have been
identified in 59 installations consisting of approximately 125 modular
1 4
units.' Table 7-2 presents the list of modular incinerator installations
and their waste throughput rates. Municipal modular units exist in
23 States, but the majority, or roughly 41 percent, exist in only two
States, New Hampshire and Arkansas.
Municipal waste incinerators are potential sources of cadmium-
containing air emissions because cadmium is a trace component of both the
combustible and noncombustible fractions of municipal waste. Cadmium is
most likely to be found in municipal waste as a component of plastics,
paint, and paper. One study has found cadmium levels in combustible
municipal waste to range from 3 to 68 ppm with the average level being
15 ppm.5 The combustible fraction of waste from a second incinerator
contained
9 ppm.6
most of
cadmium ranging from 2 to 22 ppm with an average level reported at
Upon incineration at temperatures of 1,200°C (2,192°F) or greater,
the cadmium contained in municia1 waste is vaporized since the
point of cadmium is 765°C (1,410°F).7
boiling
7.2
PROCESS DESCRIPTION
The primary purpose of incineration as a solid waste disposal technique
is volume reduction of the waste material. The majority of existing
municipal waste incinerators in the United States use a basic multiple
chamber combustion design to accomplish this purpose. These chambers are
either refractory-lined or water-walled and are equipped with grates upon
which waste is burned. Depending on the particular incinerator design,
these grates may be traveling, rocking, circular, or reciprocating. Other
design variables that may be incorporated into the basic multiple chamber
incinerator include manual or automatic stoking and starved or excess air.
The combustion process in a multiple chamber waste incinerator
(conventional or modular) occurs in two stages. The first stage takes place
in the primary combustion chamber where the solid waste fuel is dried,
ignited, and combusted. In most cases, natural draft or slight induced
112
-------
TABLE 7-2. MODULAR MUNICIPAL WASTE INCINERATION FACILITIES1,4
Plant Waste Handling Average Waste
Facility Location Capacity, Mg (Tons)/Day Rate, Mg (Tons)/Yra
Tuscaloosa, AL 270 (300) 28,080 (31,200)
Sitka, AI< 22.5 (25) 2,340 (2,600)
Batesville, AR 49.5 (55)b 5,148 (5,720)
Stuttgart, AR 54 (60) 5,616 (6,240)
Augusta, AR 19.8 (22) 2,059 (2,288)
Kensett, AR 14.4 (l6) 1,498 (1,664)
Osceola, AR 54 (60) 5,616 (6,240)
Hot Springs, AR 216 (240) 22,464 (24,960)
Bentonville, AR 54 (60) 5,616 (6,240)
Hope, AR 54 (60) 5,616 (6,240)
Siloam Springs, AR 39.6 (44) 4,118 (4,576)
Blytheville, AR 64.8 (72) 6,.739 (7,488)
North Little Rock, AR 90 (100) 18,360 (20,400)
Atkins, AR 15.3 (l7) 1,591 (1,768)
Windham, CT 113 (125)b 11 ,700 (13,000)
Pahokee, FL 39.6 (44) 4,118 (4,576)
Orlando, FL 216 (240) 22,464 (24,960)
Port Orange, FL 108 (120) 11 ,232 (12,480)
Burley, ID 45 (50)b 4,680 (5,200)
Campbellsville, KY 90 (100) 18,360 (20,400)
Donaldsonville, LA 27 (30) 2,808 (3,120)
Payne, LA 54 (60) 5,616 (6,240)
Plaquemine, LA 54 (60) 5,616 (6,24"0)
Auburn, ME 153 (170)b 15,912 (17,680)
Kittery, ME 43.2 (48) 4,493 (4,992)
Harpswell, ME 12.6 (l4) 1,310 (1,456)
Pittsfield, MA 216 (240)b 23,464 (24,960)
Collegeville, MN 49.5 (55)b 5,148 (5,720)
113
-------
TABLE 7-2. MODULAR MUNICIPAL WASTE INCINERATION FACILITIES1,4
(Continued)
Plant Waste Handling Average Waste
Facility Location Capacity, Mg (Tons)/Day Rate, Mg (Tons)/Yra
Red Wing, MN 64.8 (72) 6,739 (7,488)
pascagoula, MS 135 (150) 14,040 (15,600)
Livingston, MT 63 (70)b 6,552 (7,280)
Durham, NH 90 (100)b 18,360 (20,400)
Groveton, NH 21.6 (24) 2,246 (2,496)
Portsmouth, NH 180 (200)b 18,720 (20,800)
Nottingham, NH 8.1 (9) 842 (936)
Candia, NH 12.6 (14) 1,310 (1,456)
Bridgewater, NH 12.6 (14) 1,310 (1,456)
Meredith, NH 25.2 (28) 2,621 (2,912)
Canterbury, NH 8.1 (9) 842 (936)
Pittsfield, NH 12.6 (14) 1,310 (1,456)
Wilton, NH 27 (30) 2,808 (3,120)
Litchfield, NH 19.8 (22) 2,059 (2,288)
Wolfeboro, NH 16.2 (18) 1,685 (1,872)
Cuba, NY 108 (120) b 11 ,232 (12,480)
Skaneateles, NY 27 (30) 2,808 (3,120)
Wrightsville Beach, NC 54 (60) 5,616 (6,240)
Tahlequah, OK 108 (120) 11 ,232 (12,480)
Cleveland, OK 19.8 (22) 2,059 (2,288)
Miami, OK 64.8 (72)b 6,739 (7,488)
Coos County, OR 54 (60) 5,616 (6,240)
Johnsonville, SC 45 (50) b 4,680 (5,200)
Crossville, TN 54 (60) 5,616 (6,240)
Dyersburg, TN 73.8 (82)b 7,675 (8,528)
Lewisburg, TN 36 (40)b 3,744 (4,160)
Refugio, TX 19.8 (22) 2,059 (2,288)
Terrell, TX 48.6 (54) 5,054 (5,616)
114
-------
TABLE 7-2.
MODULAR MUNICIPAL WASTE INCINERATION FACILITIES1,4
(Continued)
\'
Facility Location
Plant Waste Handling
Capacity, Mg (Tons)/Day
Average Waste
Rate, Mg (Tons)/Yra
Waxahachie, TX
Salem, VA
Bellingham, WA
54
90
94
(60)
(100)
(104)
5,616
18,360
9,734
(6,240)
(20,400)
(10,816)
a
Determined by assuming an operation schedule of 8 hrs/day, 6 days/wk, and
52 wks/year.
b
Value represents typical or average conditions and not capacity.
115
-------
draft is used to pull air up through the support grate to carry out the
primary combustion process. In most conventional and modular municipal
waste incineration systems, the temperature immediately above the burning
grate in the primary chamber ranges from 1,149 to 1,371°C (2,106 to 2,500°F).
The combustion gases from the primary chamber, which are made up of the
volatile components of the waste and the products of combustion, are then
passed through a flame port connecting the primary chamber to the secondary
combustion chamber. The temperature of the gases leaving the primary
combustion chamber range from 760 to 871°C (1,400 to 1,600°F). From the
flame port, the heated gases flow into the secondary 'chamber where secondary
air is added for mixing and oxidation purposes. Abrupt changes in the speed
and direction of the primary combustion products causes turbulent mixing
with the secondary air and more complete oxidation is achieved. Depending
on the design of the incinerator, the hot gases exiting the secondary
chamber may be either processed to recover their heat energy and then
exhausted to a control device or ducted directly to an emission control
1 8
system. '
The basic configurations of several conventional municipal waste
I incinerators are illustrated in Figure 7-1.2 Prevalent modular incinerator
3
systems are shown in Figure 7-2.
Cadmium emissions from municipal waste incinerators are significantly
affected by the vaporization of cadmium in the waste, which is caused by the
high temperatures encountered in the combustion chambers. The vaporization
and subsequent condensation mechanisms that take place in these systems
apparently causes cadmium to consistently be enriched in the fine fly ash
particles that the units release. One test of municipal waste incinerator
cadmium emissions before control indicated that about 80 percent of the
cadmium present is associated with particles less than 3 microns in diameter
9
and that 50 percent is present in particles less than 1 micron. Figure 7-3
graphically illustrates these data. In another test of a large municipal
waste incinerator, 66 percent of the cadmium present (after control by
10
scrubbing) was associated with particles less than 2 microns in diameter.
Other studies of municipal waste incinerator emissions have substantiated
6
this apparent fine particle enrichment trend.
116
-------
"OUCI
I'll
a.
....
....
.....
'.&11(
UICI(""I AI,
I'Ll.,.. CNA8II(81
Figure 7-1.
"aU
""'-lOIINf
O&llPf'
""¥tuNC (;It"ln
UCOMOa.,
COr4U\ 1101
CM..r.
CIU( II(N
1 a..,
flOODED "'" If
WAlLS
CN&IICINC
IO'f'f'
........." COooIIA 1101
CN"",U
IIPPI' CAa1(
"COLE (;ItaTf
c.
CMa~1NC CONVf"08
b.
COooIU\IION '''' 'LOW
lO8E' CA" 1[
'UIOUf
OUEII(N 1_'
'LUf
.........., CN.uoIU
IIOYINC
"'alf
"" TII)N&II'
CO'" If
KCONO"U
COooIIA lION
C"MlE8
1 ° ".~"U
aND \1&(&
. 2
Typical configurations of conventional municipal waste incinerators.
.WUf
DI\CNAII(;I
'LY a\N
Dt\CMAllCI
-------
......
......
00
Figure 7-1.
d.
CUluOtlHt
O&ooPf ."
" A(1t
e.
I CIOI-- CIIIATEI
.....'tOt GAAtl
\..eIN..... AI. ...........
Ova"'", - DuCts
"01&(;1
...,
C"'N[
Suei/OfNtf
CH&IIIfl
nOR ACE
'IT
ClUfNt" ,......,
Typical configurations of conventional municipal waste incinerators (continued).2
-------
SECONOAAY CHAMBER
-Bt.ANER
LOADMl
g-+
5ECONDARV
CHAMBER
/,\;
-------
ACCESS DOOR
po-
..
BLOWER
! SECONOAJ CHAMBER
..q: 0
/F'IRE DOOR
PAMMY CHAMBER
. I. \
LOADeA
/
'BU~ERS/ 0.
T ,0
J
BURNER -.;..
BLOWER
d. Configuration of two horizontal rectangular chambers
with one above the other.
ST AQ(
TIPPING flOOR. .
-+
HOPP£R
SECONOMY
CHAMBER
ELECTROSTATIC
PAECIPIT ATOR
PAMMY CHAMBER
WITH MOYINQ GRATE
WATER TUBE BOILER
e. Configuration of Clear Air's incinerator-heat recovery
system with two horizontal rectangular chambers aligned
one after the other.
Figure 7-2.
Typical configurations of modular waste incinerators
(continued) .3
120
-------
eu,..,. -
a
SECONDARY
CHAMBER
D
PAlMARY
CHAMBER
LOADER
.
ACCESS DOOR
f. Configuration of Burn-Zol's two vertical cylindrical
chambers with one above the other.
HOPPER
FLUE GAS OUTlET
~ TO SCRUBBER
GATES
REFUSE CHUT!-
AFTER
BURNER
GATES
IGNmON BURNER
\
g. Configuration of Giery's incinerator with a rotary
grate in the primary chamber.
Figure 7-2.
Typical configurations of modular waste incinerators
(continued).3
121
-------
-
a: e.0
UJ
~ 4.0
~ 3.15
Q 3.0
(,)
~ 2.5
ct
Z 2.0
~
o
ffi 1.5
ct
,3,
I
I
I
,
1
I
I
1
1
,
1
I
I
I
~'
_I
01
IIJI
2,
I
,
I
1
,
1
,
I
1
1
CADMIUM
TOTAL
PARTICULATE:
I
1
I
I
I
,
I
I
1
I
Figure 7-3.
20 !O 40 50 60 7'0 80
CUMULATIVE PERCENT
Particle size distribution of total particulate and 1
cadmium emissions from a municipal waste incinerator.
122
-------
The preferential enrichment of cadmium from municipal waste
incinerators onto smaller, submicron size particles is potentially explained
in two ways. The ~irst explanation for the enrichment behavior involves the
chemical form that I cadmium exists as in the primary combustion chamber. In
the combustion chamber cadmium exists predominantly as cadmium oxide fumes
which are typically submicron in size. The second and equally important
explanation pertains to the apparent situation that cadmium is selectively
adsorbed on smaller particles in incinerator gases because of their higher
1 11
surface to volume ratios relative to larger particles. '
The small particle enrichment tendency exhibited by cadmium is
especially important in assessing overall cadmium emissions control from an
incinerator. Referring to Figure 7-3, to obtain a 50 percent control level
for cadmium, all particles greater than 0.96 microns in diameter would have
to be removed. The achievement of 80 to 90 percent cadmium removal would
necessitate the collection of particles in the 0.3 to 0.5 microns size
range. Many control systems designed to primarily reduce general particu-
. .
late matter emissions cannot capture particles in the 0.3 to 0.5 micron size
range. Efficient particulate matter removal does not therefore generally
equate to efficient cadmium removal. Higher efficiency particulate control
equipment is required to remove a specified percentage of cadmium than to
remove the same specified percentage of total particulate.
7.3
EXISTING CONTROLS
7.3.1
Conventional Incinerators
The existing controls known to be in place on conventional municipal
waste incinerators are presented in Table 7-3. The types of controls used
and the relative percentages of each are summarized below. 1
ESP - 50 percent of the sources
Low energy scrubber - 18 percent of the sources
Wet settling chamber - 7 percent of the sources
,
Cyclone - 4 percent of the sources
Baghouse - 4 percent of the sources
Unknown - 17 percent of the sources
123
-------
TABLE 7-3.
ESTIMATED EXISTING CADMIUM EMISSIONS FROM CONVENTIONAL
MUNICIPAL WASTE INCINERATORS
Site Name
Location
Existing Control Device
Existing Cadmium
a
Emissions, Mg (Tons)/Yr
UNITS WITHOUT HEAT RECOVERY
Ansonia Ansonia, CT . Low pressure scrubber 0.518 (0.570)
Stamford Stamford, CT ESP 0.382 (0.420)
New Canaan New Canaan, CT Low energy venturi scrubber 0.261 (0.287)
East Hartford East Hartford, CT Wet settling chamber 0.518 (0.570)
SWRC 111 Washington, D.C. Multiclones and ESP 0.319 (0.350)b
.....
N Orlando Orlando, FL ESP 0.218 (0.240)
~
Dade County Dade County, FL ESP 0.522 (0.574)
Waipaho Honolulu, HI ESP 0.977 (1.07)
East Chicago (Nicosia) East Chicago, IN Wet settling chamber, spray 0.844 (0.928)b
tower, plate scrubber
Louisville Louisville, KY Low energy scrubber 6.14 (6.75)
Shreveport Shreveport, LA Cyclone 0.659 (0.725)
Baltimore Baltimore, MD ESP 2.09 (2.30)
Fall River Fall River, MA High energy scrubber and ESP 1.17 (1.29)
Framingham Framingham, MA Baghouse 0.859 (0.945)
-------
TABLE 7-3.
ESTIMATED EXISTING CADMIUM EMISSIONS FROM CONVENTIONAL
MUNICIPAL WASTE INCINERATORS (Continued)
Existing Cadmium
Location Existing Control Device a
Site Name Emissions, Mg (Tons)/Yr
Bridgewater Bridgewater, MA Baghouse 1.29 (1.42)
St. Louis (#1) St. Louis, MO Low energy scrubber 0.903 (O~993)
St. Louis (#2) St. Louis, MO Low energy scrubber 1.26 (1.39)
Grosse Point Grosse Pt'., MI Unknown d 1.3 (1.43)
South East Oakland Oakland, MI Unknown d 1.3 (1.43)
Red Bank Red Bank, NJ Low energy scrubber 0.218 (0.240)
~
N Hunt;ington Huntington, NY c 1.25 (1.38)
V1 Low energy scrubber & ESP
Oyster Bay Oyster Bay, NY Low energy scrubber 5.16 (5.68)
Tonawanda Tonawanda, NY Wet settling chamber 0.730 (0.803)
Lackawanna Lackawanna. NY Wet settling chamber 2.92 (3.21)
South Brooklyn New York. NY ESP 2.17 (2.39)
Green Point New York, NY ESP 2.17 (2.39)
NRP Dayton Dayton. OH ESP 1.3 (1.43)
SRP Dayton Dayton, OR ESP 1.3 (1.43)
Lakewood Lakewood. OH Cyclone 0.641 (0.705)
East Central Philadelphia, PA ESP 2.13 (2.34)
North West Fhiladelphia, FA , ESF 2.13 (2.34)
-------
TABLE 7-3.
ESTIMATED EXISTING CADMIUM EMISSIONS FROM CONVENTIONAL
MUNICIPAL WASTE INCINERATORS (Continued)
Site Name
Location
Existing Control Device
Existing Cadmium
a
Emissions, Mg (Tons)/Yr
Webber County
Webber County, PA
ESP.
0.370 (0.407)
0.520 (0.572)
Shippensburg
Shippensburg, PA
Low energy scrubber
Newport News
Newport News, VA
ESP
0.911 (1.0)
1.13 (1.24)
Portsmouth
Portsmouth, VA
Wet settling chamber
Sheboygan
Sheboygan, WI
Low energy scrubber
0.774 (0.851)
I-'
N
0'
UNITS WITH HEAT RECOVERY
Pinellas County
Pinellas County, FL
d
Unknown
North West
Chicago, 1L
ESP
3.55 (3.91)
4.02 (4.42)
Resco
Saugus, MA
ESP
2.50 (2.75)
3.01 (3.31)
0.042 (0.046)b
Baltimore
Baltimore, MD
ESP
Braintree
Braintree, MA
ESP
Hempstead
Hempstead, NY
ESP
1. 79 (1. 97)
3.38 (3.72)
Betts
New York, NY
ESP
New Hanover County
d
Westchester County, NY Unknown
d
New Hanover County, NC Unknown
3.35 (3.69)
0.355 (0.391)
Westchester County
Akron
Akron, OH
d
Unknown
Columbus
Columbus, OH
ESP
1.60 (1. 76)
0.887 (0.976)
-------
TABLE 7-3.
ESTIMATED EXISTING CADMIUM EMISSIONS FROM CONVENTIONAL
MUNICIPAL WASTE INCINERATORS (Continued)
Existing Cadmium
a
Site Name Location Existing Control Device Emissions, Mg (Tons)/Yr
Harrisburg Harrisburg, PA ESP. 1.81 (1.99)
Nashville Nashville, TN ESP 1.81 (1-;99)
Gallatin Gallatin, TN Unknown d 0.355 (0.391)
Harrisonburg Harrisonburg, VA Unknown d 0.124 (0.136)
Norfolk Navy Norfolk, VA ESP 0.902 (0.992)
Public Works
..... d
N Langley Air Force Base Hampton, VA Unknown 0.356 (0.392)
.....
Waukesha Waukesha, WI ES~ 0.197 (0.217)
TOTAL 77 .39 (85.14)
a
Emissions are expressed in terms of total cadmium.
bThis estimate is the result of actual incinerator source testing and is not based on the emission
estimation procedure outlined in Section 7.4.
c
Low energy scrubbers on the two manual stacking units and an ESP on the reciprocating unit.
d
Exact control device is unknown, however, for the purpose of calculating an emissions estimate,
ESP control at 90 percent efficiency for general particulate matter is assumed. All of these units
are relatively new and it is expected that an ESP is required.
-------
The predominant use of ESP's, particularly on newer units, to control
municipal incinerator particulate matter emissions appears to be a function
of their high overall particulate removal efficiencies, their relative ease
of operation, and reliability. In the last published EPA review of the new
source performance standard for municipal solid waste incinerators, ESP's
were deemed to represent best demonstrated control technology for incinera-
8
tor particulate matter emissions. Existing ESP devices on municipal
incinerators have estimated total particulate matter removal efficiencies in
the range of 90 to 99 percent. However, because of the fine particle
enrichment behavior exhibited by cadmium, cadmium emission reductions from
existing ESP control devices are expected to be significantly less than the
90 to 99 percent range. In one case which demonstrates this point, a
municipal waste incinerator controlled by an ESP with a designed particulate
removal efficiency of 93 percent was tested and found to be only 74 percent
efficient for particulate removal. The cadmium removal efficiency was only
66 percent across the ESP, which is approximately 71 percent of the designed
12
total particulate removal level. .
Low energy scrubbing systems, having typical pressure drops of 6 to
10 inches water gauge, have been shown to be ineffective at not only
attaining total particulate matter emission standards, but also particularly
ineffective at reducing trace metal emissions from municipal waste incinera-
tors.S Test results reported in the literature suggest that scrubber
pressure drops on the order to 30 to 40 inches water gauge would be required
to obtain good removal of trace metals such as cadmium from incinerator
exhausts.
Wet settling chambers represent one of the earliest devices used to
control particulate matter emissions from municipal waste incinerators. Wet
settling chambers generally involve the use of wetted baffle walls to
provide wetted impingement surfaces for reducing particle velocity and
causing deposition. Such a system is only useful for collecting larger/
denser particles. The fine particles likely to contain the majority of the
cadmium present in a municipal waste incinerator would not be noticeably
affected by a wet settling system~
128
-------
Cyclone control devices employed on municipal incinerator emissions
would be only marginally effective on fine particle cadmium emissions.
The
cyclones currently:used on muni~ipal waste incinerators are judged to only
I 1
be about 50 percent efficient at removing total particulate emissions.
Given the results in Figure 7-3 on total particulate matter/cadmium particle
size distribution, the control of 50 percent of total particulate emissions
by cyclones may involve the collection of only a minimal amount of cadmium-
containing particles.
Baghouses are applied to control municipal incinerator emissions on
only a limited basis even though the control device is considered the most
effective method for overall particulate matter (particularly fine particles)
removal from an emission stream. Baghouse use as a control for incinerator
emissions is not prevalent primarily because of operational, maintenance,
and reliability problems associated with the devices when used on
incinerators. These problems basically exist because of the high temper-
ature and potentially high moisture and high corro~ion conditions that are
.. J. ,
cha~acteristics of incinerator emission streams. Too high a gas temperature'
can burn the filter bags and too Iowa temperature with a high moisture
content can cause bags to become encrusted with particle deposits. There~
fore, incinerators with a highly variable input waste heat and moisture
content must have rigid monitoring and control systems to insure proper
baghouse operation.8 Installing, operating, and maintaining the equipment
needed to make baghouses effective and reliable incinerator control systems
may increase the cost of using baghouses beyond the point of being cost
competitive.
7.3.2
Modular Incinerators
Control device and controllability information for modular incinerators
is generally non-existent in the literature. Because of the relatively
small waste handling capability of these units, particulate emission control
requirements usually do not apply and most of the modular incinerators are
expected to be uncontrolled.
129
-------
Modular incinerators are reported to be produced with and without
built-in emissions control equipment. The most predominant. built-in control
device on modular units is an afterburner which is used to oxidize unburned
vapors and combustible particles resulting from the primary incineration
operation. While such afterburners may be useful in reducing the total
outlet particulate loading, they would be ineffective at reducing cadmium or
other trace metal emissions from a modular incinerator. As shown in
Figure 7-2, modular incinerators are also reported to be controlled by ESP's
and wet scrubbers; however, no installation of either type of device has
been verified. The two modular incineration facilities for which emission
source tests are available in the literature are both uncontrolled.3
7.4
EXISTING EMISSIONS
7.4.1
Conventional Incinerators
Estimates of existing cadmium emissions from. municipal waste
incinerators are given in Table 7-3. Total existing cadmium emissions from
the conventional waste incineration part of the municipal waste source
category are projected to be approximately 77 Mg {8S tons)/yr. The deriva-
tion of this estimate was based on actual source test data for conventional
incinerators and several assumptions which are discussed below.
The emission estimates presented in Table 7-3 were calculated using the
following approach.
1. Uncontrolled particulate matter emissions for each incinerator
were estimated using the emission factors given in Reference 2.
The emission factor used for incinerators without heat recovery is
17g PM/kg waste burned, while the factor for incinerators with
heat recovery is 14g/kg. An example of how uncontrolled incinera-
tor particulate matter emissions were calculated is shown below.
(i)
ll& x 20,000 Mg (waste) x 1,000 kg
kg yr Mg
-
340 Mg PM
yr
130
-------
2.
The typical cadmium level in incinerator particulate matter
emissions was assumed to be 1.500g/Mg. This concentration was
derived from similar measured data reported in references 6. 12.
13. and ~4. Uncontrolled cadmium emissions from each incinerator
were estimated as follows.
(ii)
340 Mg
yr
1.500 g
Mg
-
0.51 Mg Cd
yr
x
3.
Because of the preferential small particle enrichment exhibited by
cadmium. cadmium emissions reduction by incinerator controls is
assumed to not be directly proportional to overall particulate
matter emissions reduction. Data reported in reference 12 support
this assumption. In this test of a municipal waste incinerator
controlled by an ESP. the cadmium removal efficiency was 29 percent
less than the designed particulate matter removal efficiency.
This non-proportionality with particulate matter emissions control
was taken into consideration during the development of cadmium
control efficiencies for each incinerator. Because the 29 percent
figure in reference 12 is the only one available for all incinera-
tors regardless of the control device in place. it was used to
modify the particulate matter emission reductions reported in
reference 1 to reflect a more realistic cadmium emissions reduction.
For example. if the given particulate emissions reduction is
90 percent. then the cadmium control efficiency is assumed to be
29 percent less than 90 or 63.9 percent (i.e.. 36.1 percent of
uncontrolled emissions are released).
4.
The uncontrolled cadmium emission rate determined from step 2
above was multiplied by the percent of total emissions released.
as determined in step 3. to estimate controlled cadmium emissions.
(iii)
-
0.184 Mg Cd
yr
0.361
0.51 Mg
yr
x
131
-------
If the particulate matter control efficiency had been 60 percent,
the controlled cadmium emissions calculated would.be
(iv)
0.51 Mg
yr
x
0.574
.
0.293 Mg Cd
yr
5.
The procedures shown above in steps 1 - 4 were followed in the
calculation of cadmium emission estimates for all the conventional
municipal waste incinerators except SWRC HI/Washington, D.C.,
Nicosia/East Chicago, Indiana, and Braintree/Braintree, Massachu-
setts.
For these three units, cadmium emissions estimates were
determined from the measured results of source tests on the units
and their controls.
.In general, the cadmium emission levels that are estimated using this
process appear to potentially be high when compared to the measured source
test data.
For example, the measured cadmium emission rate for the Braintree
incinerator is almost'five times less than the estimated rate for the
Waukesha incinerator even though the Braintree unit processes, on an annual
average, more than twice the waste of the Waukesha incinerator. Both
incinerators are controlled by an ESP. Given the scarcity of data on
individual facilities, it is not possible to reconcile inconsistencies such
as this.
In view of other cadmium emissions estimates for this source category
that have been reported in the literature, the 77 Mg (85 tons)/yr total
(exclusive of modular units) appears to be reasonable. Cadmium emissions
for municipal waste incinerators have been reported to range from 14.5 Mg
1 15
(16 tons)/yr to 118 Mg (131 tons)/yr.' The 77 Mg (85 tons) estimate from
this study is roughly equal to the midpoint of this range. The most recent
attempt to estimate municipal waste incinerator cadmium emissions incorporated
much of the input data used in this study; however, it assumed cadmium
removal to be directly proportional to particulate matter removal. The
cadmium emission estimate produced by this assumption was 34.7 Mg
(38.3 tons)/yr.
l~
-------
7.4.2 Modular Incinerators
Estimates of ~xisting cadmium emissions for modular municipal waste
incinerators were calculated using an emission factor which is based on the
total annual quantity of waste burned by an incinerator. The annual waste
throughputs of the 59 modular installations are given in Table 7-2 and were
obtained directly from references 1 and 4. The cadmium emission factor used
in these calculations of 0.007 kg Cd/Mg waste is the average of three
modular incinerator cadmium emission factors that were determined by actual
incinerator source testing.3,16 The three factors that have been measured
by source testing are 0.0046 kg/Mg, 0.006 kg/Mg, and 0.0108 kg/Mg. All of
these emission factors represent uncontrolled emissions.
Total existing cadmium emissions from modular municipal waste
incinerators are about 3 Mg (3.3 tons)/yr. This total should be viewed as
an uncontrolled estimate since no controls-have been verified for the
modular incinerators identified in Table 7-2.
An itemized, facility-by-
1 . . .
facility breakdown of modular municipal waste incinerator emissions is given.
in Table 7-4. Of the 3 Mg (3.3 tons) of existing cadmium emissions, 1.35 Mg
(1.48 tons) or 44 percent are attributable to just nine of the 59 installa-
tions. Of the remaining 50 installations, average cadmium emissions are
0.033 Mg (0.036 tons)/yr and 86 percent of these 50 sites have estimated
cadmium emissions less than 0.05 Mg (0.055 tons)/yr.
7.5
ESTIMATED BEST CONTROL (EBC) RECOMMENDATIONS
7.5.1
Conventional Incinerators
.
As discussed in Section 7.3, an ESP is the most predominant control-
device currently applied to reduce emissions from conventional municipal
waste incinerators. Available data indicate that ESP's are providing the
highest level of emissions control for conventional incinerators, including
cadmium emissions control, and they appear to have minor operational
<
problems relative to other controls used in the incinerator category that
133
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TABLE 7-4.
ESTIMATE OF EXISTING CADMIUM EMISSIONS FROM
MODULAR MUNICIPAL WASTE INCINERATORS.
Estimated Cadmium
Incinerator Facility Location a
Emissions, Mg (Tons)/Yr
Tuscaloosa, AL 0.197 (0.216)
Sitka, AI< 0.016 (0.018)
Batesville, AR 0.036 (0.040)
Stuttgart, AR 0.039 (0.043)
Augusta, AR 0.015 (0.016)
Kensett, AR 0.011 (0.012)
Osceola, AR 0.039 (0.043)
Hot Springs, AR 0.159 (0.174)
Bentonville, AR 0.039 (0.043)
Hope, AR 0.039 (0.043)
Siloam Springs, AR . 0..029 (0.032)
Blytheville, AR 0.048 (0.052)
North Little Rock, AR 0.037 (0.041)
Atkins, AR 0.011 (0.012)
Windham, CT 0.082 (0.090)
Pahokee, FL 0.029 (0.032)
Orlando, FL 0.159 (0.174)
Port Orange, FL 0.079 (0.087)
Burley, ID 0.033 (0.036)
Campbellsville, KY 0.129 (0.141)
Donaldsonville, LA 0.020 (0.022)
Payne, LA 0.039 (0.043)
Plaquemine, LA 0.039 (0.043)
Auburn, ME 0.111 (0.123)
Kittery, ME 0.032 (0.035)
Harpswell, ME 0.009 (0.010)
Pittsfield, MA 0.157 (0.173)
134
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TABLE 7-4.
ESTIMATE OF EXISTING CADMIUM EMISSIONS FROM
MODULAR MUNICIPAL WASTE INCINERATORS. (Continued)
Incinerator Facility Lpcation .
Estimated Cadmium
Emissions, Mg (Tons)/Yra
Collegeville, MN
Red Wing, MN
Pascagoula, MS
Livingston, MT
Durham, NH
0.036 (0.040)
0.047 (0.052)
0.098 (0.108)
0.046 (0.050)
0.129 (0.141)
0.016 (0.018)
0.131 (0.144)
0.0059 (0.0065)
0.009 (0.010)
0.009 (0.010)
0.018 (0.020)
0.0059 (0.0065)
0.009 (0.010)
0.020 (0.022)
0.015 (0.016)
0.012 (0.013)
0.079 (0.086)
0.020 (0.022)
0.039 (0.043)
0.078 (0.086)
0.015 (0.016)
0.047 (0.052)
0.040 (0.044)
0.033 (0.036)
0.039 (0.043)
0.054 (0.059)
0.026 (0.029)
Groveton, NH
Portsmouth, NH
Nottingham, NH
Candia, NH
Bridgewater, NH
Meredith,. NH . .
Canterbury, NH
Pittsfield, NH
Wilton, NH
Litchfield, NH
Wolfeboro, NH
Cuba, NY
Skaneateles, NY
Wrightsville Beach, NC
Tahlequah, OK
Cleveland, OK
Miami, OK
Coos County, OR
Johnsonville, SC
Crossville, TN
Dyersburg, TN
Lewisburg, TN
135
-------
TABLE 7-4.
ESTIMATE OF EXISTING CADMIUM EMISSIONS FROM
MODULAR MUNICIPAL WASTE INCINERATORS (Continued)
Incinerator Facility Location
Estimated Cadmium
Emissions, Mg (Tons)/Yra
TOTAL
0.015 (0.016)
0.036 (0.039)
0.039 (0.043)
0.173 (0.191)
0.069 (0.076)
3.04 (3.34)
Refugio, TX
Terrell, TX
Waxahachie, TX
Salem, VA
Bellingham, WA
aEmissions are expressed in terms of total cadmium.
136
-------
are effective on cadmium-containing particles. Based on its potential
ability to effectively reduce cadmium emissions when properly designed and
operated and the predominance of the technology at existing incinerators,
ESP's are recommen~ed as the leading EBC candidate for reducing cadmium
emissions from conventional municipal waste incinerators. Wet scrubbers,
the second most prevalent control device used to reduce conventional
incinerator emissions, would not be effective at controlling fine particle
cadmium emissions unless they are operated at very high pressure drops, i.e.
approximately 30 to 40 inches water gauge. Even under these conditions, no
data are available for incinerators to verify that cadmium would be removed
effectively.
Using the recommended EBC device of an ESP, the target cadmium removal
efficiency that is recommended to be reasonable is 90 percent. This level
of removal appears to be achievable for a properly designed and properly
operated and maintained ESP, particularly in view of the cadmium removal
efficiencies that have been reported for ESP's in service on fuel combustion
sources. 17 Cadmium emissions under EBC for each incinerator we~e calcula~ed .
by assuming that EBC emissions equal 10 percent of estimated uncontrolled
existing cadmium emissions (see Section 7.3 for procedures on existing
emissions). Table 7-5 presents a summary of the estimated cadmium emissions
of conventional incinerators under EBC conditions.
Total EBC cadmium emis-
sions for the conventional incinerator part of the municipal waste incinera-
tion source category are 18.6 Mg (20.4 tons)/yr or 58.8 Mg (64.7 tons)/yr
less than estimated existing emissions. The sizeable emissions reduction
predicted to occur under EBC is primarily related to the projected low
control efficiency currently being achieved on fine cadmium-containing
particles being emitted from municipal waste incineration. However, because
of a lack of extensive, measured test data to support the existing cadmiu~
emissions estimate, the projected large emissions reduction caused by EBC
implementation may be overstated.
Under the scenario of EBC in place on all sources, existing incinerators
not currently controlled by ESP's are assumed to add them to totally replace
existing controls or to augment existing controls to the extent necessary to
137
-------
TABLE 7-5.
ESTIMATE OF CADMIUM EMISSIONS FROM CONVENTIONAL
INCINERATORS WITH EBC IN PLACE
Site Name Location EBC Emissions, Mg (Tons)/Yra
UNITS WITHOUT HEAT RECOVERY
Ansonia Ansonia. CT 0.090 (0.099)
Stamford Stamford, CT 0.106 (0.117)
New Canaan New Canaan, CT 0.060 (0.066)
East Hartford East Hartford, CT 0.090 (0.099)
SWRC III Washington. D.C. 0.319 (0.351)
Orlando Orlando. FL 0.060 (0.066)
Dade County Dade County. FL 0.145 (0.160)
.Waipa~o Honolulu. HI 0.271 (0.298)
East Chicago (Nicosia) East Chicago. IN 0.196 (0.216).
Louisville Louisville. KY 0.716 (0.788)
Shreveport Shreveport, LA 0.102 (0.112)
Baltimore Baltimore. MD 0.578 (0.636)
Fall River Fall River. MA 0.361 (0.397)
Framingham Framingham. MA 0.120 (0.132)
Bridgewater Bridgewater, MA 0.180 (0.198)
St. Louis ((II) St. Louis. MO 0.241 (0.265)
St. Louis (112) St. Louis. MO 0.337 (0.371)
Grosse Point Grosse Pt.. MI 0.361 (0.397)
South East Oakland Oakland. MI 0.361 (0.397)
Red Bank Red Bank. NJ 0.026 (0.029)
Huntington Huntington. NY 0.180 (0.198)
Oyster Bay Oyster Bay. NY 0.601 (0.661)
138
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TABLE 7-5.
ESTIMATE OF CADMIUM EMISSIONS FROM CONVENTIONAL
INCINERATORS WITH EBC IN PLACE (Continued)
Site Name Location EBC Emissions, Mg (Tons)/Yra
Tonawanda Tonawanda, NY 0.151 (0.166)
Lackawanna Lackawanna, NY 0.601 (0.661)
South Brooklyn New York, NY 0.601 (0.661)
Green Point New York, NY 0.601 (0.661)
NRP Dayton Dayton, OH 0.361 (0.397)
SRP Dayton Dayton, OH 0.361 (0.397)
Lakewood Lakewood, OH 0.100 (0.110)
East Central Philadelphia, PA 0.589 (0.648)
North West Philadelphia, PA 0.589 (0.648)
Shippensburg Shippensburg, PA 0 .,043 (0.047)
Webber County Webber County, PA 0.144 (0.158)
Newport News Newport News, V~ 0.253 (0.278)
Portsmouth Portsmouth, VA 0.232 (0.255)
Sheboygan Sheboygan, WI 0.090 (0.099)
UNITS WITH HEAT RECOVERY
Pinellas County Pinellas County, FL 0.983 (1.08)
North West Chicago, It 1.11 (1.22)
Baltimore Baltimore, MD 0.693 (0.762)
Resco Saugus, MA 0.835 (0.919)
Braintree Braintree, MA 0.035 (0.039)
Betts New York, NY 0.500 (0.550)
Hempstead Hempstead, NY 0.936 (1.03)
Westchester County Westchester County, NY 0.929 (1.02)
139
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TABLE 7-5.
ESTIMATE OF CADMIUM EMISSIONS FROM CONVENTIONAL
INCINERATORS WITH EBC IN PLACE (Contin4ed)
Site Name Location EBC Emissions, Mg (Tons)/Yra
New Hanover County New Hanover County, NC 0.098 (0.108)
Akron Akron, OH 0.442 (0.486)
Columbus Columbus, OH 0.246 (0.271)
Harrisburg Harrisburg, PA 0.501 (0.551)
Nashville Nashville, TN 0.501 (0.551)
Gallatin Gallatin, TN 0.098 (0.108)
Harrisonburg Harrisonburg, VA 0.034 (0.037)
Norfolk Navy Norfolk, VA 0.250 (0.275)
Public Works
Langley Air Force Base Hampton, VA 0.098 (0.108)
Waukesha Waukesha, WI 0.055 (0.061)
TOTAL 18.56 (20.42)
aEmissions are expressed in terms of total cadmium.
140
-------
achieve an overall 90 percent reduction of uncontrolled cadmium emissions.
Operators of incinerators currently controlled by ESP's are' assumed to
improve existing performance to EBC levels by modifying and optimizing the
'design of the ESP ~nd by upgrading their operating and maintenance
practices.
7.5.2
Modular Incinerators
Considering the relatively minimal amount of information available on
modular incinerators as a category, and more specifically, the lack of data
on existing emission controls and cadmium emissions, it is very difficult to
substantiate an EBC recommendation for these units. Given the existing data
base of sources, it appears that there may be only eight to ten larger
installations warranting control. These larger sources are estimated to
constitute almost half of the total modular incinerator sector cadmium
emissions.
The units where EBC is assumed to be necessary are as follows.
, ,
Tusc:a1oosa, Alabama'
Hot Springs, Arkansas
Orlando, Florida
Campbe11svi11e, Kentucky
Auburn, Maine
Pittsfield, Massachusetts
- Durham, New Hampshire
Portsmouth, New Hampshire
Salem, Virginia
An ESP is assumed to constitute EBC for these units and for the modular
incinerator sector at large for technical reasons similar to those given for
conventional units. In terms of its potential for removing fine size
cadmium-containing particles, an ESP is viewed as being the most effective
of the controls currently used successfully on incinerators.
The estimated EBC cadmium emissions of the modular incinerator sector
of the municipal waste incineration source category are given in Table 7-6.'
To calculate EBC emissions for the nine installations given above, existing
141
-------
TABLE 7-6.
ESTIMATE OF CADMIUM EMISSIONS FROM MODULAR
INCINERATORS WITH EBC IN PLACE
Incinerator Facility Location EBC Emissions, Mg (Tons)/Yra
Tuscaloosa, AL 0.020 (0.022)
Sitka, AI< 0.016 (0.018)
Batesville, AR' 0.036 (0.040)
Stuttgart, AR 0.039 (0.043)
Augusta, AR 0.015 (0.016)
Kensett, AR 0.011 (0.012)
Osceola, AR 0.039 (0.043)
Hot Springs, AR 0.016 (0.017)
Bentonville, AR 0.039 (0.043)
Hope, AR 0.039 (0.043)
Siloam Springs, AR. 0.029 (0.032)
. Blytheville,' AR, 0.048 (0.052)
North Little 'Rock, AR 0.037 (0.041)
Atkins, AR 0.011 (0.012)
Windham, CT 0.082 (0.090)
Pahokee, FL 0.029 (0.032)
Orlando, FL 0.016 (0.017)
Port Orange, FL 0.079 (0.087)
Burley, ID 0.033 (0.036)
Campbe11svi11e, KY 0.013 (0.014)
Donaldsonville, LA 0.020 (0.022)
Payne, LA 0.039 (0.043)
Plaquemine, LA 0.039 (0.043)
Auburn, ME 0.011 (0.012)
Kittery, ME 0.032 (0.035)
Harpswell, ME 0.009 (0.010)
Pittsfield, MA 0.016 (0.017)
142
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TABLE 7-6.
ESTIMATE OF CADMIUM EMISSIONS FROM MODULAR
INCINERATORS WITH EBC IN PLACE (Continued)
I
Incinerator Facility Location
a
EBC Emissions. Mg (Tons)!Yr
Coos County. OR
Johnsonville, SC
Crossville, TN
0.036 (0.040)
0.047 (0.052)
0.098 (0.108)
0.046 (0.050)
0.013 (0.014)
0.016 (0.018)
0.013 (0.014)
0.0059 (0.0065)
0.009 (0.010)
0.009 (0.010)
0.018 (0.020)
0.0059 (0.0065)
0.009 (0.010)
0.020 (0.022)
0.015 (0.016)
0.012 (0.013)
0.079 (0.086)
0.020 (0.022)
0.039 (0.043)
0.078 (0.086)
0.015 (0.016)
0.047 (0.052)
0.040 (0.044)
0.033 (0.036)
0.039 (0.043)
0.054 (0.059)
0.026 (0.029)
0.015 (0.016)
Collegeville. MN
Red Wing. MN
Pascagoula, MS
Livingston, MT
Durham, NH
Groveton, NH
Portsmouth. NH
Nottingham. NH
Candia, NH
Bridgewater. NH
Meredith, NH
Cante~bury, NH
Pittsfield, NH
Wilton. NH
Litchfield, NH
Wolfeboro. NH
Cuba. NY
Skaneateles, NY
Wrightsville Beach, NC
Tahlequah, OK
Cleveland, OK
Miami. OK
Dyersburg, TN
Lewisburg, TN
Refugio. TX
143
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TABLE 7-6.
ESTIMATE OF CADMIUM EMISSIONS FROM MODULAR
INCINERATORS WITH EBC IN PLACE (Continued)
Incinerator Facility Location
EBC Emissions, Mg (Tons)/Yra
Terrell, TX
Waxahachie, TX
0.036
0.039
0.017
0.069
1.83
Salem, VA
Bellingham, WA
TOTAL
(0.039)
(0.043)
(0.019).
(0.076)
(2.01)
aEmissions are expressed in terms of total cadmium.
144
-------
emissions (Table 7-4) were reduced by 90 percent. Total cadmium emissions
under the EBC in place scenario are 1.8 Mg (2.0 tons)/yr or"1.2 Mg
(1.3 tons)/yr less :than estimated existing emissions.
145
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7.6
REFERENCES FOR CHAPTER 7
1.
Survey of Cadmium Emission Sources. GCA Corporation. . EPA-450/3-81-013.
U.S. Environmental Protection Agency, Research Triangle Park, N.C.
September 1981. pp. 73-95.
2.
Rinaldi, G. M., et al. An Evaluation of Emission Factors for Waste-to-
Energy Systems. EPA-600/7-80-135. U.S. Environmental Protection
Agency, Cincinnati, OH. July 1980.
3.
Frounfelker, R. Small Modular Incinerator Systems with Heat Recovery:
A Technical, Environmental, and Economic Evaluation. EPA Report
No. SW-797. U.S. Environmental Protection Agency, Office of Solid
Waste, Washington, D.C. November 1979.
4.
Resource Recovery Activities Report.
pp. 91-118.
Waste Age.
November 1984.
5.
Marr, H. E., et al. Trace Elements is the Combustible Fraction of
Urban Refuse. U.S. Department of Interior, Bureau of Mines, College
Park Metallurgy Research Center. College Park, Maryland. Undated.
6.
Law, S. L. and G. E. Gordon. Sources of Metals in Municipal
Incinerator Emissions. Environmental Science and Technology.
13(4): 432-438. April 1979.
7.
CRC Handbook of Chemistry and Physics, 56th Edition.
editor. CRC Press, Cleveland, Ohio. 1975. p. B-79.
Weast, R. C.,
8.
Helfand, R. M. A Review of Standards of Performance for New Stationary
Sources - Incinerators. EPA-450/3-79-010. U.S. Environmental
Protection Agency, Research Triangle Park, N.C. March 1979.
9.
Yost, K., et a1. The Environmental Flow of Cadmium and Other Trace
Metals. Progress Report, July 1, 1973 to June 30, 1979. Prepared
National Science Foundation, Washington, D.C. Grant No. GI-35106.
10.
Jacko, R. B. and D. W. Neuendorf. Trace Metal Particulate Emission
Test Results from a Number of Industrial and Municipal Point Sources.
Journal of the Air Pollution Control Association. 12(10):989-994.
October 1977.
11.
Jacko, R. B., et ale Trace Metal Emissions from a Scrubber Controlled
Municipal Incinerator. In: Annual Meeting of the Air Pollution
Control Division of the American Society of Mechanical Engineers.
Houston, Texas. July 1975. p. 6.
12.
Golembiewski, M., et ale Environmental Assessment of Waste-to-Energy
Process: Braintree Municipal Incinerator. EPA-600/7-80-149.
U.S. Environmental Protection Agency, Cincinnati, Ohio. December 1978.
146
-------
13.
Greenberg. R. R.. et a1. Composition and Size Distributions of
Particles Released in Refuse Incineration. Environmental Science and
Technology. 12(5): 566-573. May 1978. .
14.
Greenberg. R.:R.. et a1. and R. B. Jacko. et a1. Composition of
Particles Emitted from the Nicosia Municipal Incinerator. Environmental
Science and Technology. 12(12): 1329-1332. November 1978.
15.
Coleman. R.. et a1. Sources of Atmospheric Cadmium. EPA-450/5-79-006.
u.S. Environmental Protection Agency. Research Triangle Park. N.C.
August 1979. p. 81.
16.
Peters. J. A. and W. H. McDonald. Emission Test Report. City of Salem,
Salem. Virginia. EMB Report 80-WFB-1. U. S. Environmental Protection
Agency. Research Triangle Park. NC. February 1980. .
17.
Baig. S.. et a1. Conventional Combustion Environmental Assessment.
Final Report. Prepared for Industrial Environmental Research
Laboratory. U.S. Enviromenta1 Protection Agency. Research Triangle
Park, N.C. EPA Contract No. 68-02-3138. July 1981. pp. 5-9 to 5-36.
~7
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8.0
CADMIUM PIGMENTS MANUFACTURING
This chapter discusses the cadmium pigments manufacturing industry and
its associated cadmium emissions. Section 8.1 presents a brief source
category description. Section 8.2 describes the basic production processes
and identifies cadmium emissions sources. Section 8.3 discusses the
existing control techniques used at cadmium pigments plants. Cadmium
emissions estimates are presented in Section 8.4, and Section 8.5 presents a
discussion of EBC options and the potential emissions reduction which could
be achieved by the application of EBC.
8.1
SOURCE CATEGORY DESCRIPTION
Cadmium pigments' ar~ highly stable inorganic coloring agents which are
used to produce a wide' range of brilliant shades of yellow, red, orange, and
maroon. These types of pigments are fine, discrete particles of colored'
powder with average diameters of approximately 1 micron. In application
they are distributed and suspended in a material to produce a uniformly
1
colored product.
Cadmium pigments are based on the compound cadmium sulfide, CdS, which
produces a golden yellow color. The partial substitution of zinc or mercury
for cadmium and of selenium for sulfur in the inter-crystalline structure of
these compounds results in the formation of the intermediate cadmium pigment
colors ranging from lemon yellow to maroon. Figure 8-1 illustrates the
color structure of cadmium pigments and how the addition or subtraction of a
certain chemical affects the resulting pigment shade. As illustrated,
increased sulfur leads to greater yellows, while higher selenium leads to
148
-------
....
~
\0
.:
Primrose
Zn:Cd up to
1:6 by wt.
(Cd,Zn}S,
Zinc
Lemon
CdS
Golden Yellow
Orange
Orange
Mercury
Red
Maroon
(Cd,Hg)S
Hg:Cd up to
1: 3 by wt.
Figure 8-1.
1
Cadmium pigments color rill\ge.
Selenium
Red
:.
Cd(S,Se)
Maroon
-------
deep maroons. Zinc sulfide is added to cadmium pigments to obtain greener
yellows and mercury is added to produce orange to red pigments not requiring
high temperature stabi1ity.1,2
There are two general types or groups of cadmium pigments produced and
these are known as pure or toner pigments and as extended or 1ithopone
pigments. These pigment types are distinguished by the total level of
cadmium each contains. Pure or toner cadmium pigments refer to the cadmium
sulfide or cadmium se1enide pigments discussed above. They contain, on the
average, about 65 weight percent cadmium. Extended or 1ithopone pigments
refer to pure cadmium pigments that have been diluted with barium sulfate.
The average by weight cadmium content of extended or lithopone pigments is
1 3
approximately 26 percent. '
It has been estimated that
12 - 14 percent of the total cadmium
4 5
produced in the United States is used to manufacture cadmium pigments. '
The largest industrial use for cadmium pigments is in plastics production
1 2
which consumes 75 percent of all cadmium pigments generated.' Cadmium
pigments" are used in a wide variety of thermoplastic and thermoset plastics.
The distribution of cadmium pigments use in plastics is shown below.
Plastic
Percentage Use
ABS plastic
High-density polyethylene
Polypropylene
Low-density polyethylene
Styrene
Other including PVC
35
25
15
10
10
5
Surface coating and ceramic uses are estimated to each consume approximately
10 percent of all cadmium pigments made. The remaining 5 percent of cadmium
pigments production is used as a coloring agent in miscellaneous areas
including textiles, rubber, artists' paints, porcelain enamels, and printing
i k 1,2,4,6,7
n s.
150
-------
The predominant use of cadmium pigments in
related to the physical and chemical properties
pigments. These a~vantageous properties can be
plastics manufacture is
demonstrated by the
. 1
summarized as follows.
(a) high temperature stability
(b) high indices of refraction
(c) insoluble in organic solvent, i.e., non-bleeding
(d) high resistance to chemical attack
(e) high resistance to degradation by light
(f) high opacity
(g) good resistance to color particle migration
(h) good dispersion characteristics
Despite being more expensive on a unit basis than other inorganic
pigments, cadmium pigments use is cost competitive because of the brilliant
colors they exhibit. These brilliant colors allow a smaller mount of
. cadmium pigments to be used for coloring as opposed to the amounts needed
for the lesser priced alternative pigments.
Four plants have been identified to be producing cadmium pigments in
the United States. These four and their locations are shown below.4,5,8
General Color Co. Div. of H. Kohnstamm and Co., Inc.
Newark, New Jersey
SCM Pigments Div. of SCM Corporation
Baltimore, Maryland
Harshaw/Filtrol Partnership
Louisville, Kentucky
Pigments Department of Ciba-Geigy Corporation
Glen Falls, New York
151
-------
Given that the current capacity utilization status of existing plants is 20
- 60 percent below maximum, no new facilities are projected' to be built in
3
this source category in the near future.
8.2
CADMIUM PIGMENTS MANUFACTURING PROCESS DESCRIPTION
8.2.1
Process Description
The production of all cadmium pigments is basically structured around
one generic process which is illustrated in Figure 8-2. Each of the cadmium
pigments manufacturers have, however, developed various proprietary methods
for generating pigments with particular color shades and properties.l These
proprietary modifications involve altering the portions and types of
ingredients used, varying the calcination time, and adding or deleting steps
such as filtration/washing, drying, blending, and grinding. For the
purposes of this report, only t~e basic generic cadmium pigments production
process and its cadmium emission sources are described. Plant-specific
process description data have been provided to EPA by the four plants in
question, but these data have all been labeled as confidential by the
companies and therefore cannot be presented here.3
The basic starting materials for the production of cadmium pigments are
pure solutions of either cadmium sulfate or cadmium nitrate. Cadmium
sulfate is predominantly used. These materials are either bought in bulk in
liquid form or are produced on-site at the plant using cadmium metal,
cadmium sponge (a porous, high surface-area form of cadmium metal), or'
cadmium oxide and the appropriate acid. Depending on the desired color, the
cadmium sulfate solution is then mixed with carefully controlled amounts 'of
an aqueous solution of sodium or other alkali sulfide in a precipitat~on
reactor. This procedure causes cadmium sulfide to precipitate in
crystallographic form. To produce pigments of a red shade (cadmium
su1fo-se1enides), the cadmium sulfate is reacted with an alkali
lfid 1 id 1,3,5,7,9,10
su e-se en e.
152
-------
IIII'CIII'1c:
_111""
$aleai-
(.....)
....
VI
W
s..u-
...HI...
(,.11_)
'.I'i--
...1 fI...
(1lt--"
hU...lc
Add
(1zSC'.)
rl It uU.
.. -a..
Dryl..
Calducl.
Ope... I.
.
.
.
rUtr_loa
.. "...ta.
Ca81- ,....
,- "'-".
c:.t(S,Se)
!U,Z8)S
(''',..IS
Ca681- IItI..._.
c:.t(S.Sa).
-.
(c:.t.Za)s.
-.
(CI.la)S.
-.
.
rta.o1 ''''"ct
,,,,""1101
"'I't-
..1'.'8
.1...1..
Ca81..
11''''-
Cd!S."'I.
... $V.
(c:.t,Z8IS.
-.
(c:.t,Ia)S.
laSO.
.
'1..1 ,,,--=\
,ad..I..
.
. Denotes potential cadmium emissions
sources.
Figure 8-2.
Process flowsheet for the production of cadmium pigments.l
-------
Upon completion of the batch process precipitation reaction, the
precipitates are filtered from solution, washed, and dryed. . The dryed
precipitates are very fine colored particulates; however, they possess no
pigment properties at this point. The true colors and properties of the
pigments are developed during the calcination or roasting operation.
Calcination involves heating the pigment precipitate material in a furnace
to a temperature of from 550° - 650°C (1,022° - 1,202°F). This process
converts the pigment material from a cubic to a more stable hexagonal
crystalline structure. The calcined pigment material is then washed with
0.1 N hydrochloric acid to remove the remaining soluble cadmium particles.
The product of this procedure is then water washed again, filtered, and
dried. The final cadmium pigment emerges as a filter cake, which is either
ground and packaged as a final product or is further processed (e.g.,
blended) before final packaging.l,3,9,lO
The process just described predominantly applies to the production of
pure cadmium pigments. Extended or lithopone cadmium pigments production
can be incorporated into this overall process by the two methods shown in
Figure 8-2. The first method involves the mechanical blending of barium
sulfate with the pure cadmium pigment produced by calcining. The similar
particle size and specific gravity of barium sulfate and the cadmium pigment
enhances the mixability of these compounds. The second method of lithopone
production involves adding the barium compound before the pigment mixture is
calcined. A more thorough and efficient pigment mix is achieved by using
this approach. Barium is typically added in this process to the
precipitation reactor in the form of barium sulfide. Some of the sodium
sulfide normally used is replaced by the barium sulfide. Upon reaction with
. the cadmium sulfate solution, barium sulfate is co-precipitated with the
cadmium sulfides. The rest of the cadmium pigments process proceeds as
normal and the entire co-precipitate is calcined and further processed as
needed.l,ll
Cadmium pigment products are generally sold as homogenous powders with
a typical particle size of 1 micron (ranging from 0.1 - 3.5 microns).
However, depending on the ultimate application, they can be supplied in
154
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other forms. For the plastics industry, cadmium pigments are sometimes
processed into ~redispersed forms such as master batch pellets. These
pellets are cadmium pigments which have been incorporated or dispersed into
compounded polymer resins. Other forms in which cadmium pigments are
supplied to the plastics industry are paste concentrates and liquid colors,
both of which ~llow pigment to be added to plastic resins at different
I 1
stages of the production process.
8.2.2
Emission Sources
Cadmium emissions from cadmium pigments production occur as particulate
matter because solid cadmium-containing raw materials are used in these
processes and cadmium pigment products are generally in powder form. The
release of cadmium-containing emissions from pigments production is
generally related to raw materials processing or final product h~ndling and
packaging. The major potential sources of cadmium-containing emissions from
cadmium pigments production are indicated in Figure 8-2 and are listed
below.
calcining operations
cadmium sulfate production
drying operations
grinding operations
blending operations
packaging operations
Most of these sources have two potential components of cadmium release.
Emissions can occur during the actual operation being performed (e.g.,
grinding) and these emissions are generally vented through a duct or stack
and can be termed process emissions. The second component of cadmium
release involves emissions that occur during the handling and transfer of
cadmium-containing material from one process operation to another. Such
losses can be viewed as fugitive emissions, although such emissions are
often collected and eventually vented through a stack.
From all indications, the calcining operation is the most
source of cadmium-containing emissions in the cadmium pigments
significant
production
155
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process on both a controlled and uncontrolled basis.3,5,7 The ventilation
of the calcining furnace causes the highest level of process cadmium
emissions found in pigments production. Because it is in the calcining
furnace that true pigments are formed, emissions from this furnace should
predominantly be in the form of cadmium pigment. The cadmium level of these
pigments is roughly 65 percent and 25 percent, respectively, depending on
whether it is a pure or lithopone pigment. Because calcination of all
particles may not be complete at any given point, it is possible that
calcining emissions may contain small portions of cadmium sulfides and
cadmium sulfo-selenides.
Fugitive emissions can occur from the calcining operations during
loading of the cadmium sulfide or sulfo-selenide materials and unloading of
the calcined pigments. Loading emissions by definition are in the form of
cadmium sulfide or cadmium su1fo-selenides. Concurrently, unloading
fugitive emissions contain cadmium in the form of the particular pigment
being produced.
'Cadmium sulfate production is a potential cadmium emission source only
if cadmium sulfate solution is not purchased in bulk at a particular plant.
It appears that two of the four plants identified in this source category
3
produce cadmium sulfate on-site. Cadmium sulfate production is expected to
be a minor overall cadmium emissions source because of the wet chemistry
3
nature of the process. Emissions are expected to occur as a result of
reactor venting and from material handling and transfer losses. Emissions
from either of these routes are in the form of the cadmium raw material
used, that is either cadmium metal, cadmium oxide, or cadmium sponge.
Drying operations appear to be minor cadmium emission sources, of both
process and fugitive emissions, at the majority of the cadmium pigments
plants. Fugitive emissions from drying are only associated with unloading
the dried pigment powder because the input material is a wet filter cake.
Cadmium emissions from the dryers appear to be related to the type of dryer
used. Plants using the tray design dryers have essentially no emissions.
The forms of cadmium that would be contained in dryer process or fugitive
emissions is a function of where in the overall pigments process the drying
156
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is taking place. Prior to calcining, emissions would contain cadmium as
cadmium sulfide or cadmium sulfo-selenides. Drying occurring after
calcining would release emissions containing cadmium in the form of the
particular pigment being produced.
Grinding operations appear to be a relatively significant source of
cadmium-conta~ning emissions at existing pigment plants on an uncontrolled
basis; howeve~, all plants with this type of source have controls that
render actual atmospheric emissions to a low level. This operation can have
cadmium-containing emissions as a process release and from pigment loading
and unloading activities. The form of cadmium expected to be found in
grinder emissions is dependent on the type of pigment being produced. The
amount of cadmium in these emissions is a function of whether the pigment is
pure or is a lithopone.3
During the production of cadmium pigment lithopones, blending
operations are a potential source of cadmium-containing emissions in the
forms of the blended lithopone (~25 percent cadmium) and the pure pigment
3
being blended (~65 percent cadmium). Uncontrolled and controlled cadmium
emissions from blending appear to be minor. Cadmium-containing emissions
from this source operation potentially could occur as a result of material
displacement during blending and as fugitive losses from loading and
unloading. Emissions during loading would contain the particular pure
cadmium pigment produced by calcination. Displacement and unloading losses
could contain both the pure and lithopone pigment materials.
The last source of cadmium-containing emissions in the cadmium pigments
production process is the final product packaging operation. Data on
potential emission levels from packaging are limited; however, it is
anticipated that due to 'the fine powder nature of the product pigments,
emissions would occur as a result of material displacement and handling and
transfer operations.' Relative to other major pigments production emission
sources such as calcining, packaging losses are estimated to be small.
Emissions associated with packaging would be in the form of the particular
cadmium pigment being manufactured.
157
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8.3
EXISTING CONTROLS
The primary sources of information on the existing control status of
cadmium pigments facilities are industry responses to an EPA 114 letter
survey conducted in early 1984. Fairly complete information regarding the
controls used on pigment plant emission sources was obtained for all
existing facilities. In many cases, however, this information was indicated
to be confidential by the individual plants, such that it cannot be reported
here on a plant-by-plant basis. Instead, only aggregate information on
generic cadmium pigments production emission sources is discussed.
It appears that existing emission controls ~t cadmium pigments plants
are motivated by a combination of State air pollution control requirements,
Occupational Safety and Health Administration (OSHA) standards for allowable
workplace cadmium concentrations, and the economic value of the cadmium
chemicals contained in the emission~.
Based on data contained in the 114 letter responses, the majority of
emission sources at cadmium pigments plants, that were described in
Section 8.2.2, are controlled.3 The level of existing cadmium emissions
from the pigments source category is predominantly due to two uncontrolled
and relatively major sources (one process and one fugitive in nature) within
two different facilities. More detailed information on cadmium emissions
from this source category is provided in Section 8.4. If these two
uncontrolled sources are deleted from consideration, the remainder of the
cadmium pigments production source category appears to be fairly well
3
controlled for cadmium-containing emissions. However, this
characterization of the industry as well controlled must be caveated to
indicate that the available data base only shows which emission sources are
controlled and how. It provides limited data on the efficiency of the
controls in place and on how well these controls are operated and
maintained.
Since cadmium emissions resulting from cadmium pigments production are
in the form of particulate matter, standard particulate collection devices
are predominantly used in this industry for emissions control. Process
158
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emissions are vented directly to wet scrubbers or fabric filters. Fugitive
emissions are captured in hoods, enclosures, or vacuum pick-up systems and
conveyed to a process emission control device or to a dedicated filtration
or scrubbing device. Fugitive emissions capture and control appears to have
been particularly necessitated by requirements to meet OSHA workplace
standards for cadmium.
The primary control devices currently used in the cadmium pigments
industry to collect process and fugitive emissions, associated with the
major emission sources identified in Section 8.2.2, are summarized below.3
Source
Typical Control
Calciner
Cadmium sulfate reactor
Wet scrubber
Wet scrubber
Dryers
Grinders
.'
'>":,~J ",,'
Fabric filter
Fabric filter
Fabric filter
Blenders
Packaging
Fabric filter
It should be noted that not all plants have these specific controls, or in
some cases any controls, on all the above named sources. For example, at
one facility scrubbers are used to control drying operations instead of
fabric filters. At two other plants which use tray dryers and have minimal
emissions, no controls are apparently employed. The cadmium sulfate
production operation at another facility is also uncontrolled; however, its
cadmium emissions are estimated by the specific plant in question to be
o lb/yr.3
8.4
EXISTING EMISSIONS
As was true for the information in Section 8.3 on control systems at
pigments plants, the primary data sources for information on cadmium
emission levels from cadmium pigments plants are the responses to EPA's
recent 114 letter survey. The majority of the cadmium emissions data for
the pigments production sources were estimated by the plants based on their
159
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own process data. Only a minimal number of the emission estimates in the
114 letter responses are based on actual source testing results. Cadmium
and general particulate matter emissions data were also obtained from State
air pollution control agencies and their files.
For most of the cadmium emission sources in this source category, the
calculation of annual emission estimates was relatively straightforward.
The cadmium emissions information reported in the 114 letter responses was
in terms of a cadmium (total) concentration, ~g/m3, in the source outlet
exhaust. Total gas flow for each emission source was also reported such
that a mass emission rate/time could be calculated as shown below.
3
200 ~g Cd/m
x
3
500 m /min
- 1 g Cd/min
Follow-up phone calls were made to each of the four cadmium pigments plants
and the hours of operation per year per emissions source were obtained.
Total annual emissions, expressed in terms of total cadmium, were then
calculated by the simple multiplication of hours of operation times cadmium
emissions per hour. The follow-up phone contacts to the pigments producers
revealed that the pigments production sources are all batch processes, and
as such, have emissions that are intermittent in nature. As an example of
the variability of operation in this source category, the range of hours of
operation in a given process source may be 50 - 400/yr across the category.
This variability reinforces the unique and proprietary nature of each
cadmium pigments facility.
In some cases, plants indicated that they had no data from which to
base cadmium emissions estimates, and therefore provided no estimates. The
majority of these situations occurred in connection with sources controlled
by fabric filters. In these instances, cadmium emission estimates were
prepared by using State agency total particulate matter emissions data for
the source or by making assumptions involving the outlet loading of the
control device. When particulate matter estimates were used, these were
multipled by the relative cadmium content of the stream (as a function of
the type of pigment being produced) to obtain total cadmium emissions. When
control device outlet loading assumptions were used, a fabric filter exhaust
160
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stream was assumed to have a particulate matter grain loading of 0.02 gr/ft3
of gas. Because gas flow data were available, the 0.02 gr/ft3 figure could
be used to generate a total particulate matter emission level, which in
turn, could be used to derive a total cadmium emission estimate by the
methodology employed with State agency data.
The esti~ates of existing cadmium emissions from cadmium pigments
I
plants, that were derived from the EPA 114 letter survey, are presented in
Table 8-1. Total existing cadmium emissions from the source category are
estimated to be 1,343 kg (2,962 lb)/yr. For the purpose of evaluating and
interpreting the estimates shown in Table. 8-1, a qualitative rating scale
was developed and applied to the estimates as follows.
Emissions Estimate for
Rating
General. Color
S~
D
A
A
B
Ciba-Geigy
Harshaw/Filtrol
The rating scale can be interpreted as follows:
A - Highest level of data confidence; plant supplied complete
information from which to base estimates; all or majority of plant
data based on source tests.
B - Good level of data confidence; plant supplied nearly complete
information from which to base estimates; few or no source tests
used to develop plant emissions data.
C - Fair level of data confidence; plant supplied few data from which
to base estimates, some assumptions required; no source test data
available.
161
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TABLE 8-1.
EXISTING CADMIUM EMISSIONS3E~2IMATES
FOR CADMIUM PIGMENT PLANTS' .
Plant
a
Total Emissions
kg (lb)/yr
a
Controlled Emissions
kg (lb)/yr
a
Uncontrolled Emissions
kg (lb)/yr
General Color 313 (690) 167 (368) 146 (322)
SCM 104 (230) 104 (230) 0
Ciba-Geigy 154 (340) 102 (224) 52 (116)
Harshaw/Filtro1 772 (1,702) 772 (1,702) 0
TOTAL 1,343 (2,962) 1,145 (2,524) 198 (438)
a expressed as total cadmium.
. All estimates
162
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D - Poor level of data confidence; plant supplied no cadmium emissions
data; assumptions and other alternative emission estimation
methods needed to derive cadmium emissions estimate.
8.5
ESTIMATED BEST CONTROL (EBC) RECOMMENDATION
. .
8.5.1
Recomm~nded EBC
As discussed in Section 8.1, even though cadmium pigments are produced
from one general process, each plant is unique in that it has its own
proprietary modifications of the basic process to produce their specific
pigments. For this reason, the recommendation of EBC for a unit operation
across the pigments source category is difficult to make for both process
and fugitive emission sources. The matter of EBC recommendation is further
complicated by the limited data base available on the cadmium pigments
industry. Because it is relatively small and consists of few plants, little
is available in the published literature. Also, no plant visits have been
made by EPA or its representatives to any cadmium pigments plants.
Therefore, no firsthand evaluation has been made of the adequacy of existing
controls.
Estimated best control recommendations for the pigments source category
are based on engineering judgements of standard particulate matter control
technologies and their applicability and effectiveness on cadmium pigments
production emission sources. And a strong emphasis for EBC recommendations
is placed on assessing what controls are currently used at cadmium pigments
emissions sources and what is their cadmium removal efficiency. The primary
consideration involved in selecting EBC for a source is what is the most
efficient pollutant collection available that can be applied at a reasonable
cost. Generally, for cadmium emissions from cadmium pigments production,
EBC consists of efficient particulate matter capture systems (hoods,
enclosures, vacuum pick-ups) that are ducted to efficiently designed,
operated, and maintained collection devices such as fabric filters or wet
scrubbers. More specific discussion on EBC recommendations for fugitive and
process emission sources is given in the following sections.
163
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8.5.1.1
EBC for Fugitive Emissions Sources
For fugitive cadmium emissions from pigments production sources such as
handling and transfer operations (processing equipment loading and
unloading), EBC is recommended to be a hooding, enclosure, or vacuum pick-up
system that effectively entrains fine fugitive cadmium raw material or
cadmium pigment particles and ducts them to a particulate matter collection
device. The cadmium pigments plants responses to the 114 letter survey and
follow-up phone contacts with the plants generally indicate that most
emission sources within the plants have EBC or its equivalent in place on a
pure equipment basis. However, with no first hand knowledge (i.e., visible
emission inspection) of the sources or their controls, it is not possible to
determine if EBC for fugitive emissions is currently in place from an actual
efficiency or effectiveness standpoint. As discussed in Section 8.3 on
existing controls, at least one ,facility has a significant uncontrolled
fugitive emissions source where EBC is definitely not in place. It is
probable that other fugitive emissions sources, though currently controlled,
are not employing EBC. Such a determination is impossible to make without
much more detailed data, preferably obtained from plant inspections.
8.5.1.2
EBC for Process Emissions Sources
Most process cadmium emission sources within the cadmium pigments
industry are controlled and controlled with devices that conceivably
represent EBC. Process emissions sources in this industry that are
controlled use either a wet scrubber or a fabric filter device as indicated
in Section 8.3. For the relatively small volume emissions sources at
pigments plants (102 - 103 lb/yr level), it is speculated that cost (capital
and operating) and ease of operation factors are influencing the non-use of
other devices such as electrostatic precipitators (ESP's).
Based primarily on the demonstrated and successful use of wet scrubbers
and fabric filters to control cadmium emission sources at cadmium pigments
production facilities, EBC (from an equipment standpoint) for cadmium
164
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pigments production emission sources is recommended to be equivalent to the
control devices currently in use on major process sources (see Section 8.3).
These emissions sources and the recommended EBC device are reiterated below.
Source EBC
Calciner Wet scrubber
Cadmium sulfate reactor Wet scrubber
Dryers Fabric filter
Grinders Fabric filter
Blenders Fabric filter
Packaging Fabric filter
Scrubbers are recommended as EBC for the calciner and cadmium sulfate
reactor sources instead of fabric filters because (1) scrubbers are the
predominant device currently used in the industry, (2) the calciner emits
high temperature gases that could not be handled by a standard design fabric
filter, and (3) the cadmium sulfate reactor could release some sulfuric acid
mist which would corrode and destroy the bags and other internals of a
fabric filter.
Based on limited data~ it is estimated that the wet scrubbing EBC
should be at least 90 percent efficient, while the fabric filter EBC should
3
be at least 99.6 percent efficient. From an EBC equipment standpoint only,
EBC is currently in place in the majority of the industry. From an EBC
efficiency standpoint, the available data base suggests that EBC is not
currently being achieved.3 Six dryers (five of which are tray dryers) are
known to be uncontrolled and one calciner scrubber is known to only be
3
operating at about 50 percent of the estimated EBC efficiency level. As
with EBC for fugitive emissions sources in the cadmium pigments industry, a
more precise delineation of the extent to which EBC for process emissions
sources currently exists is not possible without more source-specific
investigation and inspection.
165
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8.5.2
EBC Emission Levels
The level of cadmium emissions estimated to be emitted from cadmium
pigments plants under the scenario of EBC in place are expressed here as a
total number for the entire source category. Emissions are not expressed on
a per plant or per source basis because of confidentiality concerns
involving the identification of certain plant sources and their control
status.
As discussed in the previous section on EBC recommendations. it is not
possible with the available data to determine whether all existing controls
are achieving the recommended EBC percentage emission reduction. Therefore.
the determination of what sources are not using EBC has to be based on the
qualitative judgement of whether or not emission sources are controlled by
the recommended EBC equipment. The available information indicates that the
majority of the cadmium pigments plants ( and particularly the large
emission sources) are equipped with the recommended EBC devices, such that
EBC cadmium emission levels do not appear to be substantially below existing
emission levels.
Two facilities have been identified to have cadmium emission sources
that are either uncontrolled or that have control equipment in place that is
known to be operating below the EBC level. One facility has pigment dryers
that are uncontrolled. In calculating EBC emissions for the source
category, it was assumed that emissions from these sources would be reduced
by a 99.6 percent efficient fabric filter. This action is projected to
result in EBC emissions for this plant that are roughly 145 kg (320 lb)/yr
below existing emissions.
A second facility has a calcining furnace ventilation source, a
calcining furnace fugitives source, and a dryer fugitives source that are
respectively, controlled to a less than EBC level, uncontrolled, and
uncontrolled. For the purposes of calculating EBC emissions for this plant,
it was assumed that a 90 percent efficient scrubber was installed or the
existing scrubber upgraded to 90 percent efficiency on the ventilation
source, and a 99.6 percent efficient fabric filter was installed to control
166
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the two fugitive emission sources. The recommended EBC changes for this
facility are projected to reduce its existing cadmium emissions by
approximately 127 kg (280 lb)/yr.
For the total cadmium pigments source category, EBC level emissions are
estimated to be 1069 kg (2357 lb)/yr or 274 kg (605 lb)/yr less than the
eXisting cadmium emissions presented in Table 8-1.
167
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8.6
REFERENCES FOR CHAPTER 8
1.
Technical Notes on Cadmium:
York, New York. 1978.
Cadmium Pigments.
Cadmium Council.
New
2.
Cadmium in the Environment. Part I: Ecological Cycling.
Nriagu, J. 0., editor. John Wiley and Sons, New York. 1979.
pp. 62-70.
3.
Confidential Cadmium Docket File for Cadmium Pigments Production.
Maintained by the Pollutant Assessment Branch, Strategies and Air
Standards Division, Office of Air Quality Planning and Standards, U. S.
Environmental Protection Agency. Research Triangle Park, North
Carolina. 1984.
4.
Product/Industry Profile on Selected Inorganic Chemicals:
Cadmium Compounds. Battelle Labs. Columbus, Ohio. 1979.
Selected
5.
Yost, K., et ale Cadmium Flow in the Environment Associated with Major
Uses and Selected Inadvertent Sources. Purdue University. West
Lafayette, Indiana. 1978.
6.
Cadmium Human Risk. U. S. Environmental Protection Agency, Office of
Solid Waste. Washington, D. C. 1979.
7.
and J. Metz. Technical and Microeconomic Analyses of
Its Compounds. EPA-560/3-75-005. Office of Toxic
U. S. Environmental Protection Agency. Washington, D. C.
Sargent, D.
Cadmium and
Substances,
1975.
8.
1984 SRI Directory of Chemical Producers.
Park, California. 1984. p. 474.
Menlo
SRI International.
9.
Miles, A. J., Radian Corporation with
Kohnstamm and Company. June I, 1983.
manufacturing.
Cooney, R., General
Cadmium emissions from
Telecon.
Color/H.
pigments
10.
Telecon. Miles, A. J., Radian Corporation with Gilbert, J., SCM
Corporation. May 25, 1983. Cadmium emissions from pigments
manufacturing.
11.
Telecon. Brooks, G. W., Radian Corporation with Salina, A. J., General
Color/H. Kohnstamm and Company. July 24, 1984. Questions on cadmium
emissions data reported in 114 letter response.
12.
Confidential letter from Fagel, L. B., Ciba-Geigy to Brooks, G. W.,
Radian Corporation. August 31, 1984. Cadmium emissions from pigments
manufacturing.
168
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APPENDIX A
TECHNICAL MEMOS DESCRIBING RATIONALES FOR EXCLUDED SOURCE CATEGORIES
Six technical memos are included in this appendix to help explain why
the following source categories are not included in the cadmium background
study.
Primary Copper Smelters
Secondary Copper Smelters
Secondary Lead Smelters
Secondary Zinc Smelters
Iron and Steel Facilities (including Basic Oxygen Furnaces,
Electric Air Furnaces, and Open Hearths)
Cadmium Stabilizer Manufacturing
Nickel-Cadmium Battery Manufacturing
The primary memo explaining the rationales why these source categories are
not included is dated October 17, 1984 - Cadmium Emission Source Categories
Not Included In The Cadmium Background Document. The other five memos offer
supporting technical data to the conclusions in the October 17th memo. It
should be noted that although cadmium pigments manufacturing is discussed in
some of these memos, this source category was still included in the cadmium
summary document because the preliminary estimated risks posed by pigments
manufacturing cadmium emissions were deemed by EPA to be significant enough
to warrant further study of the source category.
169
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RADIAN
CORPORATION
MEMORANDUM
TO:
FROM:
DATE, :
SUBJECT:
Introduction
Ray Morrison
Pollutant Assessment Branch, EPA
Garry W. Brooks
Radi~n Corporation
October 17, 1984
Cadmium Emission Source Categories Not Included in the Cadmium
Background Document
The purpose of this memorandum is to summarize the reasons why the
following eight cadmium emission source categories were not included in the
cadmium background document being prepared to support a potential cadmium
listing decision.
cadmium pigments plants
cadmium stabilizer plants
nickel-cadmium battery plants
secondary copper smelters
secondary zinc smelters
secondary lead smelters
primary copper smelters
iron and steel plants
.-
The primary reasons for not including these source categories involve a
consideration of one or more of the following factors.
(1) the estimated level of cadmium emissions from the sources
(2) The degree of control currently in use and the extent to which
this control approximates estimated best control (EBC)
(3) the projected population exposure and risk posed by cadmium
emissions from the sources
(4) the impacts of other regulatory programs by which the sources are
affected
Data presented in this memorandum were predominantly developed during a
cadmium data assessment project Radian conducted for EPA under EPA Contract
No. 68-02-3513, Work Assignment 33. The exposure and risk results presented
here were prepared by EPA based on the cadmium data developed by Radian
during this previous cadmium project.
'170
Progress Center/3200 E. Chapel Hill Rd./Nelson Hwy./P.O. Box 13000/Research Triangle Park, N.C. 27709/(919)541.9100
-------
2
Discussion
For the cadmium pigments, cadmium stabilizer, nickel-cadmium battery,
secondary copper smelter, and secondary zinc smelter source categories,
exclusion from the cadmium background document is based on a consideration
that cadmium emissions from these source categories are estimated to be
relatively low, current emission controls represent, in many cases, EBC, and
the projected cancer incidence risks to the population are relatively low.
Cadmium emission levels and current source category cpntrols for these
five source categories have been summarized and discussed previously in
another set of technical memoranda, which are provided as Attachment. 1.
Table 1 summarizes the cadmium emissions and control situation for the
source categories covered in Attachment 1. From Table 1, it is important to
note that ESC is estimated to essentially be in place in all five source
categories.
Projected exposure and risk levels for the population exposed to
cadmium emissions from these five source categories are given in Table 2.
These data were generated by EPA using the Human Exposure Model (HEM) and
input data developed during the preparation of the technical memoranda in
Attachment 1. The data in Table 2, particularly the incidence and maximum
risk numbers, are important in the decision not to include these source
categories in the cadmium background document because the levels of the
numbers are generally below that which EPA has established as significant in
terms of presenting a public health risk. . - .
The combination for all five source categories of low risk, low
emissions, and ESC in place indicates that the cadmium pigments, cadmium
stabilizer, nickel-cadmium battery, secondary copper smelter, and secondary
zinc smelter source categories do not warrant further, more detailed
examination in a cadmium background document study.
Secondary lead smelters are not being included in the cadmium
background document because their cadmium emissions have been estimated to
pose a relatively low health risk to the population and individual plant
cadmium emissions are low. An EPA analysis of risk from secondary lead
smelter cadmium emissions indicated that the annual incidence of cancer in
the exposed population is about g.022 and the maximum lifetime risk to which
someone is exposed is 1.53 x 10.. Total national cadmium emissions from
the 35 active secondary lead smelters in the U. S. are approximately 888 kg
(1954 lb)/yr of which four plants con~titute 46 perce~t. The average
cadmium emissions level-from the rema1ning 31 plants 1S only 15.6 kg
(34.3 lb)/yr.
Primary copper smelters are not being included in the background
document because their existing cadmium emissions have been estimated to
pose a relatively low health risk to the population and existing cadmium
emissions are estimated to be lowered (and, consequently, risk will be
171
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3
TABLE 1. STATUS OF CADMIUM EMISSIONS AND CONTROLS FOR
SELECTED CADMIUM EMISSION SOURCE CATEGORIES
Source Category
Maximum Estimated
Cadmium Emissionsa
kg{lb)/yr
1344 (2962)
209 (461)
100 (220)
<227 (SOO)
109 (240)
EBC in Place
Cadmium Pigments
Cadmium Stabilizers
Yesc
Yesb
Nickel-Cadmium Batteries
Secondary Copper Smelters
Yes
Yes
Secondary Zinc Smelters
Yes
aEmissions expressed in terms of total cadmium.
bBased on company responses to a 114 letter survey.
cESC is in place for the majority of the. industry; however. one process
source and one fugitive source do not have ESC in place. and emissions
from these two sources dominate the industry.
172
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4
TABLE 2.
POPULATION EXPOSURE AND RISK ESTIMATES FOR SELECTED
CADMIUM EMISSION SOURCE CATEGORIES
Exposurea Annual Maximum
Source Category (persons-~g/m3) I.ncidenceb Riskc
Cadmium Pigments 3.39 x 103 0.11 3.61 x 10-4
Cadmium Stabilizers 1. 61 x 103 0.053 1. 27 x 10-4
1.42e
-------
5
lowered) due to the effects of the recently proposed NESHAP for arsenic
emissions from copper smelters. Current cadmium emissions from primary
copper smelters have been estimated by an EPA analysis to result in an
annual cancer incidence af 0.034, while the maximum risk to the most exposed
individual is 7.57 x 10-. Process and fugitive emission controls
instituted to comply with the arsenic NESHAP should also be equally as
effective in controlling cadmium emissions, thereby further reducing the
already accep~able annual incidence and maximum risk to the population.
Iron and \steel plants are not being included in the cadmium background
document principally because the projected risk to the population of this
source categor~'s cadmium emissions has been shown by an EPA assessment
(using the HEM) to be below an established level of significance. The
annual cancer incidence from cadmium emissions in the iron and steel
industry is 0.078. The grojected maximum risk to the most exposed
individual is 9.19 x 10-. The primary reason these estimated risks are so
low is that the cadmium emissions per plant, even for large facilities, are
relatively low.
174
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RADIAN
CORPORATION
MEMORANDUM
DA TE :
TO:
September 10, 1984
. Ray Morri son
Pollutant Assessment Branch
FROM:
Garry Brooks
Radian Corporation
SUBJECT: 114 Letter Survey to Cadmium Pigments and
Stabilizer Plants
The purpose of this memo is to summarize the responses received
from the 114 letters sent to four cadmium pigments plants and five
cadmium stabilizer plants. The memo is divided into two parts, one
covering pigment plants and one covering stabilizer plants. Each of the
industry parts is subdivided into the following sections.
- Source category/process description
- Cadmium emissions summary
- Emission controls summary
- Ambient monitoring data
- Exposure modeling data
It should be noted that the degree to which plant specific data can be
presented is limited because essentially all of the data in the 114
responses was marked confidential by the companies involved.
CADMIUM PIGMENTS PLANTS
Source Category/Process Description
The following four plants have been identified to be producing
cadmium pigment$. .
- H. Kohnstamm & Co., Newark, NJ
- SCM Corporation, Baltimore. MD
- Ciba-Geigy Corporation, Glen Falls, NY
- Harshaw/Filtrol Partnership, Louisville, KY
Cadmium pigments are stable inorganic coloring agents which range in
color from yellow to red and maroon. The plants listed above produce
cadmium pigment powders of the following types.
175
Progress Center/3200 E. Chapel HIli Rd./Nelson Hwy./P.O. Box 13OO0/Research Triangle Park, N.C. 27709/(919)541.9100
-------
- 2 -
- Cadmium yellow toner
- Cadmium red toner
- Cadmium yellow 1 it hip one
- Cadmium red 1 it hip one
Cadmium yellow/red toner is also known as pure cadmium yellow/red and
cadmium yellow/red lithipone is also known as extended cadmium yellow/red.
Cadmium yellqw toner contains on the average about 67 percent cadmium;
cadmium red toner 60 percent cadmium; cadmium yellow lithipone 26 percent
cadmium; and cadmium red lithipone 26 percent cadmium.
The processes used to produce cadmium pigments at the four plants
cited are basically the same. although each plant has its own unique
aspects in areas such as number of product washing. drying. and grinding
steps and manner of final product packaging. The general manufacturing
process to produce cadmium pigments involves dissolving cadmium metal.
cadmium sponge (a porous. high surface-area form of cadmium metal). or
cadmium oxide in a sulfuric acid solution. Depending on the color
desired. sodium sulfide and selenium. mercuric sulfide, or barium sulfide
are added. During .this reaction. cadmium sulfide is formed and precipitated.
The cadmium sulfide pigment is filtered. washed. and dried. usually in a
tray dryer. The colorsoare developed durJng calcining (or roasting) in
a furnace at 600 to 700 C (1.100 to 1.300 F).' After caltining~ the.
pigment. is again washed and placed in a filter press. The resulting
filter cake is ground and packaged. Figure 1 illustrates a generalized
flowsheet for cadmium pigments production. .
Potential process or point sources of cadmium emissions from the
process shown in Figure 1 are:
- the cadmium reactor.
- drying operations,
- the calciner.
- grinding operations. and
- final packaging operations.
The cadmium reactor would most likely be a source of cadmium in the form
of the cadmium raw material used in this operation. The other four
cadmium emission sources would release cadmium in the form of a cadmium
pigment. Fugitive cadmium/cadmium pigment emissions are also possible
from loading and unloading operations associated with the process sources
listed above.
Cadmium Emissions Summary
Total plant cadmium emissions for each of the four plants identified
to be producing cadmium pigments are shown below.
176
-------
....
"-J
"-J
Cadmium
c Acid - Cadmium
Cadmi urn
talyst - Sul fate
Water Reac tor ~~l"t;nn - Additives
Strike
Dryer - Wash and Tanks
,-.
Fil ter
Wash and Grinding
Fil ter Dryer -
Calciner Mills
Cadmium - Final
Pigment Packaging
Produc t
Sul furi
Ca
Figure 1.
Generalized flowsheet for cadmium pigments production.
-------
- 3 -
Kohnstanm
SCM
Ciba-Geigy
Harshaw/Filtrol
Total
690 lb/yr.
230 1 b/yr.
340 lb/yr.
1702 lb/yr.
2962 lb/yr. (as total cadmium)
I
These emissions were calculated or taken directly from data submitted by
each of the four companies. A more detailed breakdown of each plant's
emissions is provided in Table 1. The emissions estimates shown are,
for the most part, estimates or calculations on the part of the company
involved. Very few test data were available from which to base emissions
estimates. .
Emission Controls Summary
The majority of the emissions from the cadmium pigments industry
appear to be controlled based on the data shown in Table 1. The cadmium
reactor and calciner sources of the pigments plants are generally controlled
by wet scrubbers, while the higher volume particulate emission sources
such as dryers, grinding operations, and packaging operations use
predominantly fabric filters as a control technique.
Fugitive emissions are greatly lessened by the use of hooding,
enclosures, and vacuum pickup systems, all of which are ducted to control
devices. Requirements to meet OSHA standards have necessitated the
installation of many of these fugitive emission capture devices.
With the exception of one uncontrolled process source and one
uncontrolled fugitives source, the cadmium pigments source category
appears to be well controlled.
Ambient Monitoring Data
None of the cadmium pigments 114 responses contained any ambient
monitoring data for cadmium. The plants indicated that neither they nor
the State conducted monitoring around their facilities. The only source
of ambient monitoring data for cadmium pigments plants was Ciba-Geigy
which voluntarily submitted data thay had taken for their Glen Falls
facility. The cadmium concentrations measured at their four stations
are summarized below:
178
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TABLE 1. CADMIUM EMISSIONS FROM CADMIUM PIGMENTS PLANTS
Plant Total Cd Controlled Cd Uncontrolled Cd Process Cd Fugitive Cd
Emissions (lb/yr) Emissions (lb/yr) Emissions (lb/yr) Emi ssions (l b/yr) Emissions (lb/yr)
Kohnstanm 690 368 322 568 122
SCM 230 230 0 230 0
Ciba-Geigy 340 224 116 224 116
Harshaw/Fil trol 1702 1702 0 1702 0
I-' Total 2962 2524 438 2724 238
.....
\0
-------
- 4 -
Stations
1
2
3
4
1981
Range {ug/m3} . .012 - .121
12 month avg. ; .063
.002 - .040
.023
.003 - .016
.009
.013 - .087
.039
1982
Range (ug/m3)
12 month avg.
.008 - .118
.033
.005 - .070
.014
.002 - .015
.006
.007 - .085
.020
Exposure Modeling Data
For the purposes of conducting an exposure analysis for cadmium
pigments sources. input data needed to run the HEM have been developed
for each of the four pigments plants. These data are provided in
Attachment 1. Since no 114 letter response was received for Ciba-Geigy.
HEM data for this plant were estimated based on the responses of the
other three plants.
CADMIUM STABILIlER PLANTS
Source Category/Process Description
The following five plants have been identified to be producing
cadmium stabilizers.
- Ferro Corporation, Bedford, OH
- Interstab. New Brunswick, NJ
- Witco Chemical, Brooklyn, NY
- Synthetic Products. Cleveland, OH
- Nuodex, Inc.. Elizabeth, NJ
Cadmium-containing stabilizers are used to retard polymer degradation
which occurs in pOlyviny1chloride (PVC) when exposed to heat and ultraviolet
light. The stabilizers prevent discoloration and mechanical breakdown
of the material during such operations as extrusion, molding, and calendaring.
Barium/cadmium stabilizers, also called organocadmium soaps, are salts
of long chain fatty acids. They can be used as liquids (e.g. cadmium
octoate, phenolate, and decanoate), or as powders {e.g. cadmium stearate
and laurate). Liquid stabilizers are typically used in flexible PVCs.due
to economic advantages and the ease with which they can be handled.
They contain about 1 to 4 percent cadmium. Powdered forms contain about
7 to 15 percent cadmium. They are used in rigid PVC products, especially
pipes.
Attachment 1 is not included with this memo for the purposes of
thi s report.
180
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- 5 -
The production processes described in the 114 responses for stabilizer
plants demonstrated a great deal of variability. Part of the reason for
this variability may be the fact that many of the stabilizers produced
are custom blended for specific customers. This situation requires that
some flexibility be possible within the production process. The uniqueness
of each plant's process was reflected in that most declared all details
of their process design to be confidential. Despite these problems, the
general processes used to manufacture liquid and powder cadmium stabilizers
can be described.
Liquid cadmium stabilizers are prepared by dissolving cadmium oxide
(CdO) in a heated solution of the relevant organic acid and an inert
organic solvent. Following the slow acid-base reaction, the water
produced is driven off by heating. The product is filtered, and the
clear solution of the cadmium soap is then used in plastics manufacturing.
The only potential source of cadmium emissions from this process is the
loading of the cadmium oxide into the initial reaction vessel. The 114
responses revealed that in these liquid stabilizer processes, the cadmium
oxide is manually loaded into the reactors.
To produce solid or powder cadmium stabilizers, the relevant organic
fatty acid is reacted with caustic soda to make a solu~ble sodium soap.
A solution of cadmium chloride is, prepar~d by dissolving cadmium oxide.
or cadmium metal in acid. Most plants use cadmium oxide and one stabilizer
facility even manufactures its own CdO for stabilizer production. The
sodium salt of the organic acid is added to the cadmium chloride solution
at an elevated temperature to precipitate a cadmium stabilizer soap. The
resulting slurry is centrifuged, and the solid stabilizer product is
washed, dried, ground, and sometimes blended to specifications, prior to
final packaging. After the basic cadmium stabilizer has been produced,
additives and moistening agents may be combined with the soap to reach
the product required by specific customers. Like the pigments production
process, the number and sequence of grinding, blending, and packaging
operations that are performed varies depending on the exact final product
to be made. A very. simplified and generic flowsheet is shown in Figure
2 for stabilizer production.
Potential process sources of cadmium emissions from stabilizer
production include:
- the cadmium reactor,
- drying operations,
blending operations,
- CdO production operations,
- weighing operations, and
- final packaging operations.
181
-------
Cadmi till
Organic Acid
Catalyst
....
00
'N
Steam
Steam
Additives
L ! !
Additives
- Cadmium Reactor Centrifuge
Reactor (Optional) ~
Washing
- "0
- Blending Dryi ng
Grinding
- Additives
r-- Additives
~, ,
Blending Cadmi um
Final ~
r Packaging Stabil izer
. Product
F i na 1
Packaging
Cadmium
Stabil izer
Product
Figure 2. General flowsheet for the production of cadmium stabilizers.
-------
- 6 -
As with pigments production. the initial cadmium reactor woudl be a
potential source of cadmium oxide/cadmium metal. All other' identified
cadmium emission sources would release cadmium in the form of the particular
cadmium stabilizer. Fugitive emissions of cadmium raw materials and
cadmium stabilizers can potentially occur from loading and unloading
operations associated with the process sources listed above and from
materials conveyance systems.
Cadmium Emissions Summary
Total plant cadmium emissions for each of the five plants identified
to be producing cadmium stabilizers are shown below:
Ferro
Interstab
Witco
Synthetic
Nuodex
Products -
5.2 lb/yr.
5.3 lb/yr.
278 lb/yr.
172 lb/yr
0.04 lb/yr.
460.5 lb/yr. (as total cadmium)
Tota 1
These emissions estimates were calculated or taken directly from data
sU,bmi tted by each of the fi ve compani es. A more detail ed br'eakdown of
each plant's emissions is provided in Table 2. The major,ity of the
emissions estimates are not based on any actual source. testing. As
expected. the plants producing all liquid or predominantly liquid
stablizers have very low emissions. Another factor which lowers the
emission totals for all plants is that these operations are performed
intermittently and on a batch basis. The same equipment that is used to
manufacture cadmium stabilizers is also used to produce other chemical
produc ts .
8missions Controls Summary
In plants producing liquid stabilizers. fugitive cadmium oxide dust
is captured by hooding and either ducted to fabric filter devices or
directly to the air. Generally. however. because cadmium oxide particles
are large (10 to 40 ~mm) and have a high specific gravity. the tendency
for fugitive dust emissions to occur is low. The economic value of the
cadmium oxide and OSHA workplace cadmium standards are the driving
forces behind efficient capture and control.
Plants producing powder stabilizers have controls for cadmium
emissions sources that are similar to those used in the cadmium pigments
industry. The cadmium reactor sources are controlled by wet scrubbers.
All other grinding. drying. blending. weighing. and packaging sources
use fabric filters for control. Fugutive dust emissions associated with
all these process sources are controlled by the use of hooding and
183
-------
TABLE 2. CADMIUM EMISSIONS FROM CADMIUM STABILIZER PLANTS
Plant Tota 1 Cd Controlled Cd Uncontrolled Cd Process Cd Fugitive Cd
Emissions (lb/yr) Emissions (lb/yr) Emissions (lb/yr) Emissions (lb/yr) Emissions (lb/yr)
Ferro 5.2 5.2 0 5.2 0
Interstab 5.3 0 5.3 5.3 0
Witco 278 278 0 258 20
Synthetic Products 172 172 0 172 0
....
CD.. Nuodex 0.04 0 0.04 0 0.04
~
Total 460.5 455.2 5.3 440.5 20
-------
- 7 -
enclosures which are ducted to fabric filters. Requirements to comply
with OSHA standards have been the primary force behind the push to
capture and control fugitive cadmium emissions from the stabilizer
processes.
As indicated in Table 2 by the amount of uncontrolled emissions,
cadmium stabilizer plants appear to be well controlled.
Ambient Monitoring Data
None of the fine cadmium stabilizer plants submitted any ambient
monitoring data for their plants. Neither the plants nor the States
involved conduct any monitoring.
Exposure Modeling Data
For.the purpose of conducting an exposure analysis for cadmium
stabilizer sources, input data needed to run the HEM have been developed
for each of the five stabilizer plants. These data are provided in
Attachment 2.
Attachment 2 is not included with this memo for the purposes of
this report.
185
-------
RAiJ:tSAN
co...o.",..o..
MEMORANDUM
TO:
FROM:
DATE:
Cadmium Source Assessment Project File,
EPA Contract No. 68-02-3513, WA 33
Radian Corporation
January 25, 1984
SUBJECT: Summary of Cadmium Emissions from the Production of
Cadmium-Containing Plastic Stabilizers
Introduction
This memorandum summarizes information on cadmium emissions from the
production of plastic stabilizers gathered under work assignment number 33
of EPA contract number 68-02-3513, Study of Sources of Cadmium Emissions. A
brief description of the source category and its production processes is
given,. and potential emissions points are identified. Available data on
cadmiumemiss~ons are presented. Finally, estimated best control technology.
(EBC) is defined and the control status of the industry is reviewed. While
data on the plastic stabilizers industry is very limited, it appears to be a
relatively minor source of cadmium emissions.
Industry Description
Cadmium-containing stabilizers are used to retard polymer degradation'
which occurs in polyviny1ch10ride (PVC) when exposed to heat and ultraviolet
light. The stabilizers prevent discoloration and mechanical breakdown of
the material d~ring such operations as extrusion, molding, and
calendaring. 1 , Barium/cadmium stabilizers, also called organocadmium
soaps, are salts of long chain fatty acids. They can be used as liquids
(e.g. cadmium octoate, pheno1aZe, and decanoate), or as powders (e.g.
cadmium stearate and laurate). Liquid stabilizers are typically used in
flexible2P~Cs due to economic advantages and the ease with which they can be
handled.' They contain about 1 to 4 percent 'cadmium. Powdered forms
contain 7 to 15 percent cadmium and are more expens1ve.l,2 They are used in
rigid PVC products, especially pipes. About two-thirds of the stab~lizers
that are produced and used in the United States are in liquid form.
186
-------
The five companies li~ted below are involved in the production of
cadmium-based stabilizers.
Synthetic Products Company, Cleveland, Ohio
Ferro Corporation, Cleveland, Ohio
Interstab Division of AKZO, New Brunswick,
Argus Division of Witco, New York
Tenneco Chemicals, Piscataway, New Jersey
New Jersey
Process Description
LiqUi~dSt(~~61z~rs - Liquid stabilizers are prepared by dissolving
cadmium OX1 e n a heated solution of the relevant organic acid and an
inert organic solvent. Following the slow acid-base reaction, the water
produced is driven off by heating. The product is filtered, and t2e clear
solution of the cadmium soap is then used in plastics manufacture.
Solid Stabilizers - To produce solid stabilizers, the relevant organic
acid is reacted with caustic soda to make a soluble sodium soap. A solution
of cadmium chloride is prepared by dissolving cadmium metal or cadmium oxide
in acid. The sodium salt of the organic acid is added to the cadmium
chloride solution at an elevated temperature to precipitate the cadmium
soap. The resulting slurr¥ ~s centrifuged, and the solid stabilizer product
is then washed, and dri ed. ' .
Cadmium Emissions and Control Technologies
Liquid Stabilizers - As previously noted, liquid stabilizers are the
most commonly produced form. The only potential cadmium emissions point
from their production is the handling of the pulverized cadmium oxide prior
to dissolving it in the organic acid solution. However, the cadmium oxide
particles are large (10 to 40 ~m) and have a high specific gravity, so the
tendency for dust to be displaced as fugitive emissions1i~ Sow. Hoods
ducted to fabric filters are used to control emissions. " Handling
losses h8ve previously been estimated as 0.25 percent of the total amount
handled. The economic value of the cadmium oxide and OSHA wor~P3ace
cadmium standards are the driving forces for emissions control. '
Solid Stabilizers - There are more potential emissions points from
solid stabilizer production. If cadmium oxide is used to prepare the
cadmium chloride solution, it may be emitted during handling and during
addition to the acid solution. The final cadmium stabilizer product may be
emitted during drying, handling, and packaging. At the plants for which
data are available, cadmium oxide process emissions are much larger than
emissions of the stabilizer product; however, fugitive emissions have not
been quantified. Cadmium oxide emissions contain 87 percent cadmium by
weight, whereas the stabilizer is 10 percent cadmium.
187
-------
As in liquid stabilizer production, handling losses are generally well
controlled. All cadmium and pigment handling areas are equipped with dust
collectors ducted to fabric filters.
Available Data
Total controlled cadmium oxide emissions from a large stabilizer plant
in New Jersey which produces solid cadmium stearate and other forms of
cadmium stabil;izers were reported to be 0.5 kg/hr (1.0 lb/hr). Assuming
one to two eight-~our shifts five days per week, which is typical of
stabili~er plants, annual elemental cadmium emissions could be between 800
and 1,650 kg/yr (1,800 and 3,600 lb/yr). Emissions from the other four
plants are unknown, but are likely to be lower than this at plants where
only liquid stabilizers are produced.
Summary
Data on cadmium emissions are available from only one of five plants
producing cadmium stabilizers. Cadmium emissions from cadmium stabilizer
production is most dependent on whether the final form of the stabilizer is
solid or liquid. The only emissions point from production of liquid
stabilizers, the prevalent form, is handling of the cadmium oxide raw
material prior to dissolving it in solution. Using data from one plant as a
guide, total cadmium emissions from the industry are probably less than 7 Mg
(8 tons). per year. Dust collectors and fabric filters are ESC for the
industry and are widely used. Since the FDA has banned the use of
barium/cadmium stabilizers in plastics used in food pack!ging, they are
increasingly being replaced by calcium/zinc stabilizers. The industry is
not expected to grow.
188
-------
References
1.
Cadmium Association and Cadmium Council. Technical Notes on Cadmium:
Cadmium in Stabilizers for Plastics. New York, N.Y., 1978,4 p.
Kirk-Othmer. Encyclopedia of Chemical Technology, 3rd Edition, New
York, Wiley and Sons, 1978, Vol. 4, p. 387~410.
2.
3.
Telecon. Miles; A. J., Radian Corporation, with Snodgrass, L., Ferro
Corporation, June 1, 1983. Cadmium emissions from pigment and
stabilizer manufacturing.
Letter from Bergman, K. C., Snythetic Products Company, to
Campbell, J. E., Radian Corporation, October 16, 1979.
4.
5.
Telecon. Miles, A. J., Radian Corporation, with Cunningham, H., Witco
Chemicals, May 26, 1983. Cadmium emissions from stabilizer
manufacturing.
JRB Associates, Inc., Final Report. Level II Materials Balance,
Cadmium. Draft. Prepared for U. S. Environmental Protection Agency,
Washington, D.C., EPA Contract No. 68-01-5793. September 1980, p. 4-32
to 4-49.
6.
7.
Letter and attachments from Keller, B~,New Jersey Department of
Environmental Protection, to Miles, A. J., Radian Corporation.
August 2, 1983. 5 p. .
189
-------
~.,-n~.~M
i:i)~iifcila';r;'lo~
MEMORANDUM
DATE:
TO:
January 20, 1984
Cadmium Source Assessment Project File
EPA Contract No. 68-02-3513, WA 33
FROM:
Rad~an Corporation
I
SUBJECT: Summary of Cadmium Emissions from the Secondary Zinc Smelting and
Refining Industry.
Introduction
This memorandum summarizes information on cadmium emissions from the
secondary zinc smelting and refining industry gathered under EPA contract
no. 68-02-3513, Study of Sources of Cadmium Emissions. A brief description
of the source category is given,'and potential emission points are
identified. Available data on cadmium emissions are presented. Finally,
estimated best control (EBC) technology is defined, and data on the control
status 9f the industry are reviewed. It appears that the secondary zinc
industry is a relatively minor source of cadmium air emissions. .
Source Category Description
The boundaries of the secondary zinc. industry are difficult to .
precisely delineate. Currently, !pproximately 70 facilities recycle zinc
bearing materials to some degree. Of these 70, about 16 plants can be
defined as dedicated secondary zinc producers. These 16 plants account for
approximately 50 percent of the total annual output of secondary zinc
productions. The remaining zinc bearing scrap is recycled and processed by
primary zinc smelters, and about 15 percent of the total recycled zinc scrap
is processed directly by the end-use industries.
The total amount of zinc product derived from scrap in 1982 was
140,000 Mg (154,000 tons). Of this amount, 75,000 Mg (82,500 tons) was slab
zinc, 30,002 Mg (33,000 tons) was zinc dust, and 35,000 Mg (38,500 tons) was
zinc oxide. Nearly 32,000 Mg (35,200 tons) or about 43 percent of the slab
zinc was produced by dedicated secondary zinc plants. Virtually all of the
zinc dust and an estimated 153000 Mg (16,500 tons) of zinc oxide were also
produced at dedicated plants.
The largest market use for zinc metal is for galvanizing steel ,sheet.
Die-casting occupies another significant part of the zinc metal market
followed by consumption for alloying, particularly for brass and bronze.
Zinc dust is used primarily in the manufacture of paints and in many varied
chemical processes. The manufacture of tires !ccounts for about 50 percent
of the total market consumption of zinc oxide.
190
-------
The demand for zinc products is tied very closely to the automobile
industry. An overall industry reduction in the weight of automobiles has
had a significant impact on zinc demand. In 1976, an average automobile
contained 20.4 kg (45 1bs) of zinc die castings; however, in 1982, the
average vehicle only contained 10.4 kg (23 lbs). The use of zinc for
galvanizing purposes has been and will be affected by the substitution of
ga1va1ume, which contains only 43 percent zinc. Zinc oxide demand has been
adversely affected by the development of longer wearing and more durable
radial tires. Although these downward zinc demand trends are present, to
some extent they will be counterbalanced by an expanding zinc market in the
area of protective coatings and a likely i~creased in the share of final
zinc products put out by secondary plants. Overall, the demand for
secondary zinc products is not expected to increase appreciably within the
next five to ten years. Since existing secondary zinc facilities are
operating at only 50 to 70 percent of capacity, no new plants are likely to
be constructed in the foreseeable future.
The wide variability in the types of zinc scrap processed by secondary
zinc plants results in a corresponding variability in the types of processes
employed. Moreover, for each specific processing step, a number of
different types of furnaces are in use. Depending on the type of scrap
being processed, pretreatment is sometimes required prior to melting and
refining operations. Both hydrometal1urgical and pyrometal1urgical
processes are used to perform pretreatment.
Wet processing is sometimes employed to pretreat skimmings from
galvanizing baths. The skimmings are crushed, washed with water, and
allowed to settle before being slurried with sodium carbonate. The zinc
hydroxide thus formed is dried and calcined in a kiln to produce relatively
impure zinc oxide.
The more common pyrometa1lurgical pretreatment is called sweating.
Mixed die-cast scrap consisting of shredded automobile parts, appliance
parts, and some galvanizing scrap is always sweated prior to refining. In
the sweating process, the scrap is slowly melted at just above the melting
point of zinc in order to separate the metals and to drive off volatile
organic contaminants. Reverberatory, rotary, and muffle furnaces are
comrnon1y employed for sweating. The molten zinc metal produced is
immediately either refined, alloyed, or cast into slabs to await further
processing.
Relatively high-grade zinc scrap or pre-sweated scrap may be first
melted and then either cast into slabs or alloyed. Melting furnaces operate
at 430 to 590°C (776 - 1,094°F). Melting is a batch operation; each batch
takes 6 to 8 hours. Most melting is conducted in indirectly fired pot or
kettle furnaces. Reverberatory and electric induction furnaces can also be
used.
191
-------
The type of distillation process used depends on the nature of the
desired final zinc product. In all cases, the charge material is heated to
a temperature of 980 to 1,250°C (1,796 - 2,282°F) in order to vaporize the
zinc. The zinc vapors are then condensed and the zinc material collected.
For the reduction of zinc oxide, some form of horizontal retort is utilized.
The zinc oxide is mixed with water and powdered coke and heated in the
retort. The produced vapors are condensed in a ceramic cone at one end of
the retort. At 6 to 7 hour intervals, the condenser is emptied and the
molten metal ~ollected for casting into slabs.
Bottle or muffle retorts are used for the distillation of impure
metals. The products of these types of distillation operations are pure
zinc metal, zinc powder, or high-grade zinc oxide. When a metal product is
desired, the vapors are collected in a ceramic condenser which is maintained
above the melting point of zinc. For the production of zinc powder, the
vapors are cooled rapidly in a metal condenser. Zinc oxide can be produced
by venting the vapors to a refractory lined tube into which a stream of air
is introduced. The zinc combusts spontaneously to zinc oxide and is
collected in a fabric filter.
Cadmium Emissions
No data o~ emissions of cadmium from secondary zinc smelters have been
located. Very few data on'particulate emissions are available.
Nonetheless, on the basis of mass balance calculations for cadmium operating
parameters for the individual processes, and information on existing control
technologies within the industry, the total annual atmospheric emissions of
cadmium from secondary zinc plants are expected to be relatively small.
The magnitude of the overall potential for cadmium to be released
during secondary zinc processing is primarily a function of the amount of
cadmium entering in the scrap. Based on data obtained from industry
representatives and published informati~n5 6he maximum cadmium content of
various scrap materials was determined. ' ,
For each category of scrap, the maximum annual input of cadmium was
then derived (based on 1982 input/output data). Table 1 summarizes these
calculations. As shown, the estimated quantity of cadmium entering,
secondary zinc facilities in 1982 is 16 Mg (17.6 tons).' It is important to
emphasize that these values represent maximum concentrations of cadmium.
For example, the 0.014 percent cadmium in the scrap .from galvanizing
operations is based on the concentration found in wastes from spangled
products.' The galvanizing bath used for these products7has a higher cadmium
content than that found in other galvanizing processes.
The products from secondary zinc plants will contain some cadmium.
Zinc slabs from secondary plants are commonly sold back to steel
galvanizers. The cadmium content of zinc dust and zinc oxide is also
usually specified. In Table I, the average concentration of cadmium in the
192
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TABLE 1. CADMIUM MASS BALANCE FOR THE SECONDARY ZINC INDUSTRY
Zn Content Cd Content Cd In)ut
Scrap Inputs (Mg) (%) (Mg
,
Skimmings and Ashes 55,000 0.014 7.70
Galvanizing Dross 35,000 0.014 4.70
Die Casting Scrap 29,000 0.004 1.16
Fragmatized Castings 20,000 0.004 0.80
Flue Dusts 3,000 0.035 1.05
Chemical Residues 3,000 0.010 0.30
Total Input 145,000 15.91
Product 'Outputs .
Zinc Slab 75,000 0.010 7.50
Zinc Dust 30,000 0.005 1.50
Zinc Oxide 35,000 0.003 1.05
Total Output 140,000 10.05
Total Cd Dissipated 5.86
193
-------
products is given. On this basis, slightly over 10 Mg (11 tons) of cadmium
are estimated to remain in the zinc. Thus, less than 6 Mg' (6.6 tons) of
cadmium could be expected to be dissipated from the secondary zinc industry
each year. .
The above calculations included all facilities recycling zinc. When
. the derived values are prorated to reflect only dedicated secondary zinc
plants, a maximum cadmium input of 8.8 Mg (9.7 tons) and an expected cadmium
output of 5.2' Mg (5.7 tons) are obtained. This would correspond to a
maximum potential dissipation of cadmium (i.e., uncontrolled emission rate)
from these plants of 3.6 Mg (4 tons)/year.
Control Status of Industry
The available information on the current status of particulate control
within the secondary zinc industry indicAtes that ESC for cadmium emissions
is, for the most part, already in place. In most instances, all of the
potential sources of process cadmium emissions are collected in a system of
dampered hoods which are ducted to a common fabric filter. Electrostatic
precipitators are installed at some plants instead of fabric filters.
Offgasses from sweating operations are usually first treated with an
afterburner in order to control organics and to reduce the particulate load
to the fabric filter.
The extent of fugitive cadmium emissions from secondary zinc, plants is
not known. However, there is little reason to expect that they would be
significant. Most of the raw materials processed at these plants are large
objects; materials storage and transfer would not likely be a source of
fugitive emissions. Emissions from charging and tapping of the furnaces
will be at least partially controlled by the various hoods installed over
. them. No major visible fugitive emissions were9reported during a site visit
to the largest secondary zinc plant in the U.S.
In the source category survey cited above8, an industry-wide
particulate emission control efficient of 97 percent was estimated.
Applying this efficiency proportionally to cadmium, the annual release of
cadmium to the atmosphere from the dedicated secondary zinc industry would
be a little over 100 kg (220 lbs). The assumption made above, that
emissions of cadmium will be proportional to emissions of total
particulates, can be justified on the basis of the operating parameters for
the individual processes employed within the industry. As reviewed earlier,
most of these processes operate at temperatures of 450 to 600°C
(842 - 1.112°F). This is below the cadmium boiling point of 767°C
(l,413°F). Given the low concentration of cadmium in the scrap, the vapor
pressure of the cadmium would be negligible at these temperatures. As a
result. there is no physical means for the cadmium to be emitted
preferentially. In the high temperature refining operations--distillation,
reduction. and oxidating--the method of product recovery ensures that
emissions (products) will be captured to the greatest extent feasible.
There is no significant difference, between the size of zinc and cadmium
particles. .
194
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Summary
Future growth in the secondary zinc smelting industry is expected to be
moderate. To the extent that growth occurs, it is likely to be uneven.
No cadmium emission information is available for the secondary zinc
source category. However, based on a mass balance approach, only a small
amount of the cadmium entering the secondary zinc industry is likely to be
dissipated to the atmosphere. Existing hooding and fabric filter controls
on process emissions represent EBC for cadmium emissions from this
industrial source category. All plants currently appear to be using EBC.
Based on observations of visible emissions, fugitive cadmium emissions from
secondary zinc facilities have been estimated to be minimal.
195
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References
1.
Telecon. Dykes, R. M., Radian Corporation, with Jolly, J. and Willis,
H., U.S. Bureau of Mines, August 11, 1983.
Bureau of Mines. 1983. Mineral Commodity Surveys. U.S. Department of
the Interior.
2.
3.
Bureau o~ Industrial Economics. U.S. Industrial Outlook, 1983. U.S.
Department of Commerce.
Telecon. Keller, L., Radian Corporation, with Hogan, J., American Iron
and Steel Institute, August 5, 1983.
4.
5.
Cotterill, C. H. and J. M. Cigan (eds.) AIME World Symposium on Mining
and Metallurgy of Lead and Zinc. The American Institute of Mining
Metallurgical, and Petroleum Engineers, Inc., N.Y., N.Y., 1970.
Versar, Inc. Technical and Microeconomic Analysis of Cadmium and Its
Compounds. U.S. Environmental Protection Agency, EPA 560/3-75-005.
6.
7.
Telecon. Keller, L., Radian Corporation, with Dunbar, C., ARMCO, Inc.,
August 5, 1983. .
Emissions Standards and Engineering Division. Source Category Survey:
Secondary Zinc Smelting and Refining Industry. U.S. Environmental
Protection Agency, EPA-450/3-80-012.
8.
9.
Telecon. Mead, R. C., Radian Corporation, with McElroy, A. D., Mid-West
Research Institute, August 5, 1983.
196
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Rj.\iOlj.1~]
co...o...,.o..
MEMORANDUM
TO:
Cadmium Source Assessment Project File,
EPA Contract No. 68-02-3513, WA 33
Radian Corporation
FROM:
DATE:
January 25, 1984
SUBJECT: Summary of Cadmium Emissions from the Secondary Copper Smelting and
Refining Industry
Introduction
This memorandum summarizes information on cadmium emissions from the
secondary copper smelting and refining industry gathered under EPA contract
no. 68-02-3513, Study of Sources of Cadmium Emissions. A brief description
of the source category and processes is given, and potential emission points
are identified. Available data on cadmium emissions are presented. Finally,
estimated best control technology (EBC) is defined, and data on the control
status of. the industry are reviewed. ~t appears that the secondary copper
industry is a relatively minor source of cadmium air emissions.
Source Category Description
There are six secondar~ copper refining plants in the United States.
These are listed in Table 1. Only those plants manufacturing pure copper or
copper alloys other than brass and bronze have been included in this study.
The final product produced by these plants is the same as copper from primary
producers. Cadmium may be emitted from these plants because the copper scrap
they use as a raw material can contain cadmium. In particular, copper alloys
used in heavy copper wi~e, electrical contacts, and car radiators contain
about 1 percent cadmium. The secondary copper plants recover and purify
copper from the scrap by smelting it in a series of furnaces which emit
cadmium-containing particulates including cadmium oxides and cadmium metal
fumes. A generalized flow sheet of the process is shown1in Figure 1, however
the number and type of furnaces vary from plant to plant. 1T!b4e 2 lists all
potential sources of process and fugitive cadmium emissions' '. The blast
or cupola f~rnace is the largest particulate and cadmium emissions source at
most plants.
Cadmium Emissions
Few cadmium emissions data are available for the industry. WhilS ~lAnts
monitor other heavy metals, cadmium has not been considered a problem' , .
Only one plant has tested to determine the cadmium level in its emissions.
197
-------
TABLE 1.
SECONDARY COPPER SMELTING AND REFINING PLANTSl,5
Approxlutea -..
Production Estimated Capacity Annua} Operation flna I
CoIapany lOC4tton E8ployees Mg/llOnth Tons/llOnth Mg/~th Tons/llOnth (hr) Product
Southllflre Georgia 200b 2.120b b 2.720" 3.000b 8.400 Ca thode copper
3.000 .
Cerro Copper Prod. l111nols 900 3.990 4.400 . 3.99Od 4.4ood 5.280 Cathode copper
alEHETCO 11110015 200 2.210 2.500 . 2.120 3.000 8.400 Ca thode copper
U.S. Metals Refining Hew Jersey 1.600 14.440 15.920 14.440d 15.920d 8.400 . Cathode and
OfIlC copper
franklin SMelting Pennsylvania 150 1.360-1.500 1.500-1.650 1.500 1.650 8.400 Black and blister
and Refining copper
. Nassau Recycling South Carol1na 1.200 6.350c 1.000c 9.450 10.420 8.400 Cathode and fl re
refined copper
....
\D
co
aHours for Elting or fire refining operations.
bEstl8ate (1975) data.
cApproxlllate.
dCapacity 11.lted by electrolytic refining capacity.
-------
The four plants which refine low grade copper scrap using cupola or Top-Blown
Rota~y Converter (TBRC) fu~naces would have the greatest pqtential for
cadmlum in their raw materlals an~ ,m~ssions. The other two remaining plants
deal in purer non-alloyed copper. " Of the four plants processing low
grade scrap, two (CHEMETCO and Southwire) ~xIOude cadmium alloys from their
raw materials and monitor to confirm th~s.' USMR does not routinely assay
raw materials or emissions for cadmium. Franklln1zmelting and Refining
Company has tested their emissions for cadmium. '
Controlled particulate emissions from the baghouse handling process and
captured fugitive emissiorts from the cupola furnace at Franklin Company were
measured with a high-volume filter sampling train and found to contain
0.041 percent cadmium. The total annual elemental cadmium emissions would be
1.79 kg/yr (3.95 lb/yr). The concentration of cadmium in controlled
converter furnace process emissions was less than 0.0005 percent. Total
annual cadmiuTle~~sf!ons from this furnace would be less than 0.064 kg/yr
(0.14 lb/yr). " The total elemental cadmium emissions from this plant
would therefore be about 1.85 kg/yr (4.09 lb/yr).
If USMR, which has the largest production capacity in the industry as
well as one of the highest annual particulate emissions rates,1 had the same
percentage of cadmium in its process emissions, it would emit about 67 kg/yr
(148 lb/yr) of cadmium from the cupola and 1.9 kg/yr (4.1 lb/yr) from the
converter. As previously stated, other plants claim not to have cadmium in
their raw. materials or emisf~o~,. State agencies were not aware of any
cadmium emissions problems. - Using Franklin Co. and USMR as guides,
total annual cadmium emissions by the industry are probably less than
450 kg/yr (500 lb/yr).
Control Status of Industry
Fabric filters are the estimated best control technology (EBC) for
process cadmium emissions from this industry. All plants currently use
fabric filters on all ~r~6e!1 furnaces with the exception of CHEMETCOand
Cerro Copper Products." CHEMETCO uses a quencher, venturi scrubber,
and mist-eliminator series on their TBRC furnaces. These systems have a
tested particulate collection efficiency, of 98.4 perce~t., Since
cadmium-containing particulates have simllar characterlstlcs to the total
stream, cadmium collection efficiencies would probably be similar. The
holding furnace is uncontgolaed but emits less total particulates and cadmium
than the controlled TBRCs t . Cerro Copper Products uses high energy wet
scrubbers on their anode furnaces to achieve a control efficiency of .
97 percent. The shaft furnace is uncontrolled, but again emiss less total
particulates and cadmium than the controlled anode furnaces.
Some type of fugitive emissions control at charging and tapping holes
are in place at every plant. These consist of various configurations of
hooding a~d i~ one case an evacuated chamber on the charge door of a cupola
furnace:l, ,7- 1 There are few data on fugitive particulate emission rates
199
-------
Depleted Stag
(Sell or Landfill)
LOW GRADE SCRA'
(} Refinery Srass
Q) Copper
Searing
Scrap
-------
TABLE 2. SOURCES OF CADMIUM EMISSIONS FROM THE SECONDARY
COPPER REFINING PROCESS.
Emissions Source
Type of Emissions
Cupola Furnace
Holding Furnace
Process, Fugitive (charge door, tapping)
Fugitive (tapping, slagging hole)
Converter Furnace
Process, Minimal FU9itive (converter
outlet, charge door)
Process, Minimal Fugitive (charge door)
Anode and Fire-
Refining Furnace
Shaft Furnace
Process, Minimal Fugitive
Process, Fugitive (capping, charging)
TBRC Furnace
201
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and none on fugitive cadmium emissions rates. However,
who visited two of the six plants while preparing EPA's
survey said he could see no visible fugitive emlisions.
he visited were representative of the industry.
Summary
a consulting engineer
19~0 source category
He felt the plants
Many seco~dary copper plants exclude cadmium-containing alloys from
their raw mat~rials. At those plants which do process cadmium-containing
materials, the cupola furnace is the largest source of process cadmium
emissions. ESC is in place at all facilities, and total annual cadmium
emissions from the industry are probably less than 450 kg/yr (500 lb/yr).
There are no data on fugitive cadmium emissions; however, site visits
indicate the fugitive emissions are not a large problem, and ESC is used on
most fugitive emissions sources.
202
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References
1.
Midwest Research Institute. Source Category Survey: Secondary Copper
Smelting and Refining Industry. U.S. Environmental Protection Agency,
Research Triangle Park, N.C. EPA-450/3-80-011. May 1980.
Cadmium Association and Cadmium Council. Technical Notes on Cadmium:
Cadmium in Alloys. New York, N.Y. 1978. p.1.
2.
3.
Burton, D.J. et~. Process and Occupational Safety/Health Catalogue,
Secondary Nonrerrous Smelting Industry. National Institute for
Occupational Safety and Health, Cincinnati, Ohio. July 1979.
Umlauf, G.E. and L.G. Wayne. Emission Factors and Emission Source
Information for Primary and Secondary Copper Smelters. U.S.
Environmental Protection Agency, Research Triangle Park, N.C.
EPA-450/3-77-051. December 1977.
4.
5.
Telecon. Mead, R.C., Radian Corporation, with Shaw, H., Pennsylvania
Bureau of Air Quality Control. July 1983. Cadmium emissions from
Reading Metals Refining.
Telecon. Mead, R.C., Radian Corporation, with Filiaci, A., U.S. Metals
Refining. August 1983. Emissions from the U.S. Metals Refining Plant.
6.
7.
Telecon. Mead, R.C., Radian Corporation, with Moss, H., Nassau
Recycling. July 1983. Cadmium emissions from Nassau Recycling.
Telecon. Mead, R.C., Radian Corporation, with Tandler, P., Cerra Copper
Products. July 1983. Cadmium emissions from Cerra Copper Products.
8.
Telecon. Mead, R.C., Radian Corporation, with McKell, J.,CHEMETCO Inc.
July 1983. Cadmium emissions from CHEMETCO.
10. Telecon. Mead, R.C., Radian Corporation, with Osburn, R., Southwire
Corporation. July 1983. Cadmium emissions from Southwire.
11. Letter and Attachments from Glazer, N., Philadelphia Department of
Public Health, to Mead, R.C., Radian Corporation. July 1983.
30 pages. Cadmium emissions from Franklin Smelting & Refining Company.
9.
12. Letter and Attachments from Saltzburg, M., Philadelphia Department of
Public Health, to Fine, M., Philadelphia Department of Public Health.
October 1982. 19 pages. Particulate emissions tests and toxics tests
results.
203
-------
13. Telecon. Mead, R.C., Radian Corporation, with Glazer. N.. Philadelphia
Department of Public Health. August 1983. Cadmium ~missions from
Franklin Smelting and Refining Company.
14. Telecon. Mead, R.C., Radian Corporation. with Curtrer, E.A. Jr.,
Georgia Air Protection Branch. July 1983. Cadmium emissions from
Southwire.
,
15. . Letter from Chalmers, J.E., South Carolina Bureau of Air Quality
Control, to Mead, R.C., Radian Corporation. July 1983. 1 page.
Emissions from Nassau Recycling.
16. Telecon. Mead, R.C., Radian Corporation, with Chalmers, J.E. South
Carolina Bureau of Air Quality Control. July 1983. Cadmium emissions
from Nassau Recycling.
17. Telecon. Mead, R.C., Radian Corporation, with Keller, B., New Jersey
Bureau of Air Pollution Control. August 1983. Emissions from the U.S.
Metals Refining plant.
18. Letter and Attachments from Montney, W.A., Illinois Environmental
Protection Agency, to Mead, R.C., Radian Corporation. July 1983.
Emissions from CHEMETCO and Cerro Copper Products.
19. Telecon. Mead. R.C~. Radian Corporation, with Snyder. M.K., Midwest
Research Institute. August 1983. Site visits to two secondary copper
plants. .
204
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RAC!l,~i}J
co"po".".o"
MEMORANDUM
TO:
Cadmium Source Assessment Project File,
EPA Contract No. 68-02-3713, WA 33
Radian Corporation
FROM:
DATE:
January 25, 1984
Summary of Cadmium Emissions from Nickel-Cadmium Battery
Manufacturing.
SUBJECT:
Introduction
This memorandum summarizes information on cadmium emissions from the
manufacture of nickel-cadmium batteries. Information was gathered under
work assignment 33 of EPA contract no. 68-02-3513, Study of Sources of
Cadmium Emissions. Brief descriptions of the source category and its
manufacturing processes are given, and potential emissions points are
identified. Available data on cadmium emissions are presented. Finally,
estimated best control technology (EBC) is defined, and data on the control
status of the industry is reviewed. It appears that the nickel-cadmium
battery manufacturing industry is a relatively minor source of cadmium air
emissions~
Source Category Description
Eight companies have been identifie~ which manufacture nickel-cadmium
batteries. These are listed in Table 1.
Batteries come in a variety of sizes, configurations, and general types
of construction. Batteries are comprised of one or more cells, and there
are two major categories of battery cells: (1) sealed cells and (2) vented
or flooded cells. Both vented and sealed Ni-Cd battery cells can be made by
similar processes. Negative and positive electrodes are assemb.1ed
alternately with a separator between the electrodes to hold t~e2electrolyte
in place and to isolate the negative and positive electrodes.' Other than
the actual assembly process of the cells and ,some of the minor components,
few differences are found in the manufacture of sealed. or vented cells.
The production of the electrodes does vary among manufacturers. Two
basic types of plate construction are commonly found: (1) sintered plate, or
(2) pocket plates. In the U.S., the sintered plate construction is
predominant. Pocket plate type positive electrodes consist of perforated
nickel plated pockets filled with active materials (cadmium sponge, cadmium
205
-------
TABLE 1. NICKEL-CADMIUM BATTERY MANUFACTURERS IN THE U.S.
AND ASSOCIATED COMPANY INFORMATION
TYPE OF TYPE OF
COMPANY LOCATION BATTERY PROCESS
General Electric Gainesville, FL sealed cell sintered-
vented cell wet process
Goul d St. Paul, MN sealed cell sintered &
pocket
Union Carbide Cleveland, OH sea 1 ed cell sintered-
dry process
Saft America Valdosta, GA sealed cell s1ntered-
vented cell wet process
Marathon Waco, TX sealed cell cell
vented cell- assembly
industrial size only
McGraw Edison Greenvi1l e, NC vented cell- pocket
industrial size
NIFE Lincoln, RI vented cell- pocket
industrial size
Eagle Pitcher Colorado Springs, CO sealed sintered-
wet process
206
-------
hydroxide) in a dry state. The sintered plate process can be either a wet
or dry process. .
The sintered process involves binding of the active materials to a
nickel-plated sintered steel base structure. The voids in the structure are
filled with the active material (nickel or cadmium) by simple deposition
during soaking or by electrolytic or pressed powder processes. The pressed
powder process consists of pressing dry cid2ium-containing active materials
into the porous base structure in a mold.' The plate material is then cut
into individual plates for assembly. A flow sheet is given in Figure 1.
Cadmium Emissions
Potential sources of cadmium emissions from these manufacturing
processes are listed in Table 2.
Cadmium emissions data was solicited from all State agencies where
plants are located and from six plants. Cadmium emissions tests or
estimates were available for only two plants, GE and McGraw Edison. Others
had not tested their emissions or claimed to have no process emissions of
cadm;u~ after controls. GE has 60 to 65 percent of the sealed cell batterY3
market' and emits less than 15.2 kg/yr (33.5 lb/yr) of elemental cadmium.
McGraw Edison manufactures industrial size batteries and total process and
fugitive emissions are estimated to be 9.~ ~g?yr (21.6 lb/yr) elemental
cadmium in the form of cadmium hydroxide. " The cadmium concentration in
their emissions i~ less than the OSHA workpface standard for cadmium dust
which is 0.2 mg/m for an38ghour time weighted average with a ceiling
concentration of 0.6 mg/m .
Control Status of Industry
Both McGraw Edison and GE use dust co14e8t9r~ i8d fabric filters in
cadmium handling areas within their plants. ' , " NIFE, Union Carbide,
and Marit~~nl~lso use dust collectors and fabric filters in cadmium handling
areas. " Two other plants handle cadmium ~~1~5in solution so there
would be little potential for cadmium emissions.' Fabric filters are
known to be highly efficient particulate removal devices down to very small
size ranges. Consequently, they would be effective cadmium removal devices,
and are judged to be EBC for the industry.
Fugitive emissions are contained within the plants themselves rather
than emitted to the atmosphere. All eight plants monitor thy workplace for
cadmium in order to prove compliance with the OSHA standard. One plant was
recently visited and inspected for fugitive emissions. T~e plant was found
to be clean, and fugitive emissions were well controlled.
Summary
Based on data from two plants, total atmospheric emissions of cadmium
from the nickel-cadmium battery industry are probably on the order of about
207
-------
Nickel Plated
S teel Sintered I
Strip Formed I
Nickel Powder
Nick el Nitrate I Cadmium I
Solution ~ (A) Nitrate Solution (B) (C) I
~ ,~ + , I
Electrolytic Pressing o~
Impregnating Impregnating Deposition of Dry Cadmiury
Cadmium Powder and;
I Binder onte\
Wire Mesh
~ ~ in Mold
: ,
I Drying
Rinsing
~
KOH Solution Immersion i
~
~Jashi ng
I
Y-'
Assembly
~
KOH , LiOH - Electrolyte
- Addition
+
Test and Reject
Pack Cells
t
Product
Figure 1. Process flow sheet for the manufacture of sintered plate nickel-cadmium
batteries. Cadmium deposition is accomplished by (A) impregnation
during soaking, (B) electrolytic deposition, or (C) the pressed
powder crocess.
208
-------
TABLE 2. SOURCES OF CADMIUM EMISSIONS FROM NICKEL-CADMIUM
BATTERY MANUFACTURING
Process
Emission Sources
Sintered Plate Batteries
Cadmium Nitrate Solution Method
Formulation of cadmium nitrate
solution from dry salts (however
some plants buy pre-formulated
solutions)
Drying and Assembly -
Fugitive emissions
Electrolytic Deposition
Preparation of cadmium containing
electrolyte if this involves dry
material
Dry Pressing Process
Cell Assembly
Handling of dry cadmium powders
Pressing cadmium powder into metal
grid
Cell Assembly
Pocket Plate Batteries
Handling of dry cadmium hydroxide
powder
Filling of pockets in plate with dry
cadmium hydroxide
Cell Assembly
209
-------
100 kg/yr (220 lb/yr). Either wet or dry processes can be used to
manufacture batteries; the emissions points being somewhat different for
each process. Dust collectors and fabric filters are currently used at all
potential process and fugitive emissions points, so the industry is using
ESC.
210
-------
I
I '
References
1.
Simonson, A.V. et al. Industry Profile Phase I Study of Nickel.
Occupational Safety and Health Administration, Washington, D.C. DCN
#80-201-003-01-09. August 1980.
2.
Versar, Inc. Assessment of Industrial Hazardous Waste Practices:
Storage and Primary Battery Industries. Prepared for U.S.
Environmental Protection Agency. NTIS #PB-241 204. January 1975.
Sholtes and Koogler Environmental Consultants. Air Pollution Survey -
General Electric Company Battery Business Department. Prepared for
Florida Department of Environmental Regulation. February-May 1981.
3.
4.
Telecon. Mead, R.C., Radian Corporation, with Hunt, D.B., Radian
Corporation. August 1983. Previous Radian study of Ni-Cd battery
manufacturing and visit to a plant.
Copelan, V., North Carolina Division of Environmental Management.
Request for Action to be Taken and Site Inspection of McGraw Edison
Plant in Greenville, N.C. Concerning Renewal of Permit #4010R.
February 12, 1982. 1 page.
5.
6.
Permit to Construct and Operate Air Pollution Abatement Facilities
#4010R and attachments. Granted by North Carolina Division of
Environmental Management, Raleigh, N.C. to McGraw Edison Company,
Greenville, N.C. February 1979.
Telecon. Mead, R.C., Radian Corporation, with Copelan, V., N.C.
Division of Environmental Management. August 1983. Emissions from
McGraw Edison battery plant and results of site inspection.
7.
8.
9.
29 CFR 51910.1000, Table Z-2.
Interview. D.B. Hunt, Radian Corporation, with General Electric
Battery Business Company. April 28, 1980. 12 pages. Cadmium
Questionnaire.
10. Telecon. Mead, R.C., Radian Corporation, with Lusk, R., Florida Bureau
of Air Quality Management. July 1983. Cadmium emissions from General
Electric battery plant.
11. Telecon. Mead, R.C., Radian Corporation, with Nash, A., Union Carbide.
August 1983. Cadmium emissions from Union Carbide battery plant.
12. Telecon. Mead, R.C., Radian Corporation, with Norling, N., NIFE. July
1983. Cadmium emissions from NIFE battery plant.
13. Letter and attachments from Sievers, H.E., Texas Air Control Board to
Mead, R.C., Radian Corporation. July 1983. 19 pages. Emissions and
Permits for Marathon Battery Company.
211
-------
References (Continued)
14. Telecon. Mead. R.C.. Radian Corporation. with Scherer. D.. Eagle
Pitcher. July 1983. Cadmium emissions from Eagle Pitcher battery
plant.
15. Telecon. Mead. R.C.. Radian Corporation. with Wiles. C.. Saft America.
July 1983~ Cadmium emissions from Saft America battery plant.
16. Telecon. Mead. R.C.. Radian Corporation. with Crawly, E.. Minnesota
Division of Air Quality. July 1983. Cadmium emissions from Gould
battery plant.
212
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