NATIONAL INVENTORY
OF
SOURCES AND EMISSIONS:
CADMIUM - 1968
by
W. E. Davis § Associates
9726 Sagamore Road
Leawood, Kansas
Contract No. CPA-22-69-131
EPA Project Officer: C. V. Spangler
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, N.C. 27711
February 1970
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The APTD (Air Pollution Technical Data) series of reports is issued by
the Office of Air Quality Planning and Standards, Office of Air and
Water Programs, Environmental Protection Agency, to report technical
data of interest to a limited number of readers. Copies of APTD reports
are available free of charge to Federal employees, current contractors
and grantees, and non-profit organizations - as supplies permit - from
the Air Pollution Technical Information Center, Environmental Protection
Agency, Research Triangle Park, North Carolina 27711 or may be obtained,
for a nominal cost, from the National Technical Information Service,
5285 Port Royal Road, Springfield, Virginia 22151.
This report was furnished to the Environmental Protection Agency
in fulfillment of Contract No. CPA-22-69-131. The contents of this report
are reproduced herein as received from the contractor. The opinions,
findings and conclusions expressed are those of the author and not
necessarily those of the Environmental Protection Agency. The report
contains some information such as estimates of emission factors and
emission inventories which by no means are representative of a high
degree of accuracy. References to this report should acknowledge the
fact that these values are estimates only.
Publication No. APTD-68
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PREFACE
This report was prepared by W. E. Davis & Associates pursuant to
Contract No. CPA 22-69-131 with the U. S. Public Health Service,
U. S. Department of Health, Education, and Welfare, National Air
Pollution Control Administration.
The inventory of atmospheric emissions has been prepared to pro-
vide reliable information regarding the nature, magnitude, and ex-
tent of the emissions of cadmium in the United States for the year
1968.
Background information concerning the basic characteristics of the
cadmium industry has been assembled and included. Process
descriptions are given, but they are brief, and are limited to the
areas that are closely related to existing or potential atmospheric
losses of the pollutant.
Due to the limitation of time and funds allotted for the study, the
plan was to personally contact about twenty percent of the companies
in each major emissions source group to obtain the required infor-
mation. It was known that published data concerning emissions of
the pollutant was virtually non-existent, and contacts with industry
ascertained that atmospheric emissions were not a matter of record.
The cadmium emissions and emissions factors that are presented are
iii
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based on the summation of the information obtained from production
companies that represent approximately forty percent of the total
production, and the reprocessing companies that handle about forty-
five percent of the cadmium used in consumer products. Emissions
control equipment is in use at all the production facilities that were
visited. It is a part of the process system for the recovery of zinc,
and is not specifically for the control of cadmium emissions to the
atmosphere. Cadmium emissions and emissions factors are con-
sidered to be reasonably accurate.
IV
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ACKNOWLEDGEMENTS
This was an industry oriented study and the authors express
their appreciation to the many companies and individuals in
the cadmium industry for their contributions.
We wish to express our gratitude for the assistance of the
various societies and associations, and to many branches
of the Federal and State Governments.
Our express thanks to Mr. C. V. Spangler, Project Officer,
National Air Pollution Control Administration, for his helpful
guidance.
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CONTENTS
SUMMARY 1
SOURCES OF CADMIUM 2
MATERIAL FLOW
Material Flow Chart 4
Mining and Processing 5
Cadmium Metal Imports and Exports 10
Reprocessing 11
Electroplating 11
Pigments 13
Plastics 15
Alloys 16
Batteries 17
Miscellaneous 18
EMISSIONS
Map of Emission Regions 20
Cadmium Emissions 21
Cadmium Emissions Factors 22
Mining and Processing 23
Metallurgical Processing 24
Reprocessing 27
Electroplating 27
Pigments 29
Plastics 31
Alloys 33
Batteries 34
Miscellaneous 35
Consumptive Uses 36
Rubber Tires 36
Motor Oil 37
Fungicides 38
Fertilizers 38
Incineration and Other Disposal 39
Plated Metal 39
Vll
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CONTENTS
Incineration and Other Disposal
Galvanized Metal 41
Auto Radiators 42
Other 43
APPENDIX A
Plants Producing Cadmium Lead and Zinc ... 44
Vlll
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SUMMARY
The flow of cadmium in the United States has been traced and
charted for the year 1968. The apparent consumption was 13.3
million pounds, and domestic production 10.6 million pounds.
Only a small amount of cadmium was recovered from scrap.
Emissions to the atmosphere during the year totaled 4.6 million
pounds. Emissions from the metallurgical processing plants of
the primary producers of cadmium, zinc, lead, and copper were
more than 2 million pounds, and those from melting operations
in the iron and steel industry were about the same.
Emission estimates for mining, metallurgical processing, and re-
processing operations are considered to be reasonably accurate.
They are based on data obtained by personal contact with the
processing and reprocessing companies. Further effort is
recommended to confirm the accuracy of the emissions from the
scrap containing cadmium.
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SOURCES OF CADMIUM
Cadmium is a metal which is not found as a free mineral in nature.
The most important mineral is sulfide greenockite which is disper-
sed in zinc sulfide ore. Since pure cadmium is never found in a
natural state and cadmium minerals are not found in concentrated
form, metallic cadmium is always prepared commercially as a by-
product of primary metal industries, principally the zinc industry.
Cadmium, a relatively rare element, is found not only in zinc ore
but in lead ore, copper ore and other ores that contain zinc min-
erals. It is intimately associated with the zinc and when ore con-
taining several minerals is separated, the cadmium remains with
the zinc. Since the separation process is not exact, lead concen-
trates will contain a small quantity of zinc and a proportionately
small amount of cadmium. The earth's crust contains 0.55 ppm
of cadmium,_/ and field soil unfertilized 0.55 ppm to 2.45
2
ppm._/ (wet wt.)
Ores containing cadmium are found in the following states:
Arizona, California, Colorado, Idaho, Illinois, Kansas, Kentucky,
Maine, Missouri, Montana, Nevada, New Jersey, New Mexico,
1 - Schroeder, H. J. , Cadmium, Mineral Facts & Problems,
Bureau of Mines Bulletin 630, 1965
2 - Schroeder, H. A., etal. , Essential Trace Metals in Man:
Zinc Relation to Environmental Cadmium, J. Chronic Diseases
20 (4) - 179, (1967)
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NewYork, Oklahoma, Oregon, Pennsylvania, Tennessee, Utah,
Virginia, Washington, Wisconsin. Not all of these states produce
metallic cadmium and some other states do produce metallic cad-
mium from ores and concentrates shipped in from outside of the
state. Ores mined in the United States account for 38 percent of
the primary cadmium produced in the United States. The other
62 percent comes from imported ores and concentrates, and im-
ported flue dust. The principal sources of imports were Canada,
Peru and Mexico.
Some cadmium metal was imported which amounted to about
14 percent of total United States consumption. Principal imports
were from Australia, Canada, Japan, Mexico and Peru._/
World production of cadmium is essentially a by-product of zinc
smelting, and the situation is much the same in the United States.
Very little cadmium is recovered from scrap, and even less is
produced as a by-product of lead and copper refining.
1 - Bureau of Mines Minerals Yearbook - 1968
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MINING AND PROCESSING
In 1968 about ninety six percent of the cadmium produced in the
United States was primary cadmium and 4 percent was from
secondary production - 45 percent recovered from foreign ores;
36 percent from domestic ores; 15 percent from imported flue
dust; 4 percent secondary metal derived from reprocessing
scrapped alloys.
Cadmium in zinc concentrates from domestic mines is estimated
at 5,304,000 pounds (Table II). This is based on mine production
of recoverable zinc (Table I) , a zinc recovery efficiency of 83 per-
cent, and an average of 0.227 percent cadmium contained in 60
percent zinc concentrates.
Cadmium in imported zinc ores is estimated at 6,208,000 pounds
(Table IV). This is based on imports from Canada, Mexico, and
other countries (Table III) , a zinc recovery efficiency of 83 per-
cent, and an average of 0.283 percent cadmium contained in 60
percent zinc concentrates. Imported lead ores contained 163,000
pounds of cadmium, and flue dust from Mexico contained 1,605,000
pounds._/
1 - Bureau of Mines Minerals Yearbook - 1968
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-6-
TABLE I
MINE PRODUCTION OF RECOVERABLE ZINC
UNITED STATES 1968
STATE
Arizona
California
Colorado
Idaho
Illinois
Kansas
Kentucky & Maine
Missouri
Montana
Nevada
New Jersey
New Mexico
New York
Oklahoma
Pennsylvania
Tennessee
Utah
Virginia
Washington
Wisconsin
SHORT TONS
5441
3525
50258
57248
18182
3012
9702
12301
3778
2104
25668
18686
66194
6921
30382
124039
33153
19257
13884
25711
TOTAL
529446
Bureau of Mines Minerals Yearbook - 1968
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TABLE II
ESTIMATED CADMIUM CONTENT
CONCENTRATES PRODUCED IN THE UNITED STATES
1968
CADMIUM CONTENT
(Thousand Pounds)
ZINC CONCENTRATES 4827
WESTERN STATES 2083
MISSOURI - KANSAS - OKLAHOMA 370
ILLINOIS - TENNESSEE - WISCONSIN 1560
EASTERN STATES 814
LEAD - OTHER CONCENTRATES 477
TOTAL 5304
(Estimates Based on Company Confidential Data)
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TABLE III
UNITED STATES IMPORTS
ZINC ORES
1968
COUNTRY
AUSTRALIA
BOLIVIA
CANADA
GERMANY, WEST
HONDURAS
MEXICO
MOROCCO
NETHERLANDS
PERU
SOUTH AFRICA
OTHER
SHORT TONS
2267
9027
310586
5942
12959
142313
15715
3313
39899
4287
74
TOTAL
546382
Bureau of Mines Minerals Yearbook - 1968
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TABLE IV
ESTIMATED CADMIUM CONTENT
UNITED STATES IMPORTS
ZINC ORES AND FLUE DUST
1968
CADMIUM CONTENT
(Thousand Pounds)
ZINC ORE
CANADA 1755
MEXICO 3430
OTHER 1023 6208
LEAD ORE 163
FLUE DUST 1605
TOTAL 7976
(Estimates Based on Company Confidential Data)
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Cadmium production during the year was 10,651,000 pounds, in-
cluding primary and secondary metal, and the equivalent metal
content of cadmium sponge used directly in the production of
compounds. _/
CADMIUM METAL IMPORTS & EXPORTS
Cadmium metal imports totaled 1,927,000 pounds. These were
mostly from Australia, Canada, Japan, Mexico, and Peru.
Exports during the year were 530,000 pounds._/
CADMIUM STOCKS
Total industry stocks of cadmium metal at the beginning of 1968
were 1,541,000 pounds, but by the end of the year the total was
only 1,069,000 pounds. This was a 472,000 pound difference.
At the same time there was a 808,000 pound draw-down of
Government stocks.£/ During 1968, 1,280,000 pounds of
cadmium from stocks went to reprocessing.
1-2-3 - Bureau of Mines Minerals Yearbook - 1968
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REPROCESSING
The apparent consumption of cadmium in the United States during
1968 has been reported at 13,328,000 pounds.!/
ELECTROPLATING
For many years the chief use of cadmium metal in the United States
has been for electroplating, and most has been used for plating of
iron and steel. The industrial and commercial applications for
cadmium plating are numerous, including: components for aircraft,
automobiles, electrical and electronic apparatus, household ap-
pliances, radio and television sets, hardware, and fasteners. It
offers an effective protective coating against corrosion, especially
for such environments as salt water and tropical atmospheres.
For the period 1940-44, 71 percent of the cadmium used in the
United States was for electroplating (averaging 5.4 million pounds
2
per year)._/ In 1968 the consumption for that purpose was 6
million pounds or about 45 percent of the total cadmium used dur-
ing that year._/ While this is a decrease of 26 percent, the
1 - Bureau of Mines Minerals Yearbook - 1968
2 - Mentch, Robert L. and Lansche, Arnold M., Cadmium A Materials
Survey, Information Circular 7881. Bureau of Mines - 1958
3 - Frawley, E. V., American Metal Market, August 25, 1969
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amount consumed is still larger than for the 1940-44 period, and the
electroplating industry is still the largest user of cadmium. Industry
does report that there is a definite relationship between the amount
of cadmium used for electroplating and the price of the metal.
The electroplating industry has the largest number of users of
cadmium metal. The American Electroplaters Society has a mem-
bership of about eight thousand. There are many small users and
they are located in the United States near small industry; thus
they are widely distributed. The large users are located near
industrial areas; such as, automotive manufacturing centers,
etc.
In this report on cadmium the term electroplating is used to cover
all types of plating operations.
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PIGMENTS
Cadmium, first used in the sulfide form in paint pigments more
than one hundred years ago, is used today in colors for many
different purposes, including, durable enamels and finishes,
plastics, coated fabrics, textiles, rubber, glass, printing inks,
baking enamels, ceramic glazes, artists colors, etc. It is used
where extreme color retention is required and in cases of ex-
posure where heat resistance is essential.
Until about 1930, the cadmium red and yellow pigments were
essentially in the concentrated form and their use was limited;
however the subsequent manufacture of the lithopones caused a
tremendous demand for the cadmium colors.
Two cadmium compounds important in the pigment industry are
the sulfide and sulfoselenide which are often extended with barium
sulfate and then known as cadmium lithopones. The color range
of cadmium sulfide is from lemon yellow to orange, and that of
cadmium sulfoselenide from orange and light red to deep maroon.
Large quantities of the extended reds were used by the automotive
industry until 1955 when there was a world shortage of selenium
and the automotive industry turned to other coloring agents. It
is doubtful that the cadmium color industry would have shown any
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growth since the middle 1950's were it not for the rapidly expand-
ing plastics industry. Cadmium colors, being both heat and light
stable in plastics, found immediate acceptance; particularly be-
cause of high molding temperatures which would cause less stable
pigments to fail.
During 1968 cadmium used in pigments totaled nearly 2.8 million
pounds or about 21 percent of all cadmium used in the United States,
The principal use was in plastics as a coloring agent.
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PLASTICS
An important use of cadmium that is growing rapidly is in plastics.
It is used not only in pigments, but in the stabilizers that are add-
ed to polyvinyl chloride compounds to prevent discoloration during
processing as well as to maintain stability during the useful life
of the end product.
Polyvinyl chloride plastics are used for many purposes, such as
clear bottles, medical tubing, shoe soles, clear vinyl packaging
film for fresh meat, flexible tubing, garden hose, hi-fi and stero
records, house siding, wall covering, flooring, furniture, upholstery,
automobile upholstery, toys, pipe, table tops, and many other
extensively used products. The use of cadmium based stabilizers
for plastics used in food packaging has not been approved by the
USDA.
During 1968, organic and inorganic colors used in plastics totaled
112 million pounds, up ten percent from 1967, and cadmium pigments
used were 4.4 million pounds_/ (cadmium metal content - 1.8
million pounds) . During the same period the consumption of heat
stabilizers in vinyls was 65 million pounds with barium-cadmiums
2
and the chelates together accounting for 34 million pounds _/
(cadmium metal content 2 million pounds) .
1-2 "Modern Plastics", September 1969, p.p. 92 & p.p. 96
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ALLOYS
Alloying is an important use of cadmium in solders, low-melting
point alloys, bearings and brazing alloys.
Typical cadmium solders contain tin, lead, zinc, cadmium and some-
times a small amount ot copper. Others contain only cadmium and
zinc. The cadmium content in the various solders varies from
approximately ten to forty percent.
Low-melting-point alloys that contain cadmium ore are used for
fusible elements in automatic sprinkler heads, fire-detection ap-
paratus, fire-door release links and safety plugs for compressed-
gas cylinders and tanks.
Cadmium-base bearings were previously used to a greater extent
than they are today. During World War II, this was the second
largest use of cadmium, exceeding one million pounds per year.
In brazing the use of silver-cadmium alloys make it possible to
join both ferrous and non-ferrous metals with strong, leak-tight
corrosion resistant joints. The alloys used for this purpose normal-
ly contain from 15 to 25 percent cadmium.
In 1968 cadmium metal used in alloys totaled about one million
pounds. /
1 - Frawley, E. V., "American Metal Market" Aug. 25, 1969
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BATTERIES
Although the nickel-cadmium battery has been well known in the
United States for many years, its use has been somewhat limited.
It has many advantages, including - long life, simple maintenance,
maximum current delivery with minimum voltage drop, quick charg-
ing , and the ability to operate effectively over a wide temperature
range, but its price is considerably higher than for a comparable
lead-acid battery.
End uses of the nickel-cadmium battery vary from the small re-
chargeable items, such as - flashlights, electric shavers, and
cordless carving knives, to heavy equipment, such as - busses,
diesel locomotives, airplanes, and spacecraft.
In 1968, cadmium metal used in batteries is estimated to be
400,000 pounds, based on information received from manufacturers.
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MISCELLANEOUS
More than 90 percent of the cadmium used in 1968 was for
electroplating, pigments, plastics, alloys, and batteries.
Smaller quantities, totaling about 1.1 million pounds, were
used in fungicides, nuclear energy applications, phosphors
for television tubes, photography, lithography, process en-
graving, glass, x-ray screens, compounds for curing rubber,
and various other applications.
A relatively new use for cadmium in the rubber industry is
in the curing process. A product containing cadmium is used,
instead of zinc oxide, as an activator. Reports indicate that
this product is not used for tires but mainly for mechanical
rubber goods.
Cadmium in nuclear reactors has been used in the control
rods which regulate the fission rate and in other parts as a
shielding material.
Cadmium acetate is used in pottery and porcelain to produce
an iridescent effect.
Fungicides are another use of cadmium. Reports indicate
the larger quantities of the fungicides containing cadmium
are used for golf courses. During 1968, cadmium used for
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this purpose was more than 25,000 pounds.
Cadmium oxide is used for phosphors in television tubes.
It is contained in the black and white tubes, and the blue
and green in the color tubes. Other similar applications in-
clude: x-ray screens, fluorescent lamps, luminescent dials,
etc.
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SPURGE CATEGORY
CADMIUM EMISSIONS
1968
SOURCE GROUP
POUNDS
MINING
METALLURGICAL PROCESSING
REPROCESSING
Mining
Cd Separation
from .Ores
530
2,100,000*
530
2,100,000
33,528
CONSUMPTIVE USES
INCINERATION OR OTHER
DISPOSAL
TOTAL EMISSIONS
Region No. 1
Region No. 2
Region No. 3
Region No. 4
Pigments
Plastics
Alloys
Batteries
Miscellaneous
Rubber Tires
Motor Oil
Fungicides
Fertilizers
Plated Metal
Radiators
Other
TO THE ATMOSPHERE IN THE
EMISSIONS BY REGION
PLANTS
212
758
334
496
21,000
6,000
5,000
400
1,128
11,400
1,820
500
910
2,000,000*
250,000
190,000
U. S.
14,630
2,440,000
4,588,688
or
2.294 Tons
POUNDS
920,000
1,414,000
996,000
774,000
* Source groups (representing 89 percent of total emissions) in regional
distribution.
Undistributed - 11 percent
484,688
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CADMIUM EMISSIONS FACTORS
MINING
Mining and Ore Concentration NC
METALURGICAL PROCESSING
Cadmium Recovery from Zinc Concentrates C
Cadmium Recovery from Lead Concentrates C
Cadmium Refining Units C
REPROCESSING
Pigment Production C
Production of Stabilizers for Plastics C
Production of Brazing Alloys and Solders C
Nickel-Cadmium Battery Manufacture NC
CONSUMPTIVE USES
Automobile Tire Wear NC
Automobile Motor Oil (burned in engine) NC
Fungicide Spraying NC
INCINERATION & OTHER DISPOSAL
Production of Iron & Steel NC
Production of Secondary Copper NC
(from automobile radiators)
Solid Waste NC
(63,500,000 tons incinerated)
0.2 Ib/ton of cadmium in ore
284.0 Ib/ton of cadmium charged
1310.0 Ib/ton of cadmium charged
25.0 Ib/ton of cadmium charged
15.0 Ib/ton of cadmium charged
6.0 Ib/ton of cadmium charged
10.0 Ib/ton of cadmium charged
2.0 Ib/ton of cadmium charged
0.01 Ib/million vehicle miles
0.002 Ib/million vehicle miles
0.05 lb/1000 gallons of spray
0.015 Ib/ton of iron/steel produced
3.9 Ib/ton of scrap processed
0.003 Ib/ton of incinerated
solid waste
C - Controlled
NC - Not Controlled
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MINING AND PROCESSING
Since no ore is mined solely for the recovery of cadmium, the
cadmium emissions to the atmosphere resulting from mining
operations are those that occur during the mining and concentra-
tion of zinc-bearing ores.
Regardless of the type of mine (underground or open-pit) the
processing is basically the same - ore removal, ore handling,
crushing, grinding, and concentration. The ore is dry or per-
haps damp when removed from the mine, but is wet during the
grinding. It is also wet during concentration which is accom-
plished by means of a flotation process.
While this study was in progress, many mining companies were
contacted concerning the quantity of ore mined, its cadmium
content, and the cadmium emissions occuring during mining
and concentration. Most stated there were no emissions to the
atmosphere, and others indicated there were slight emissions,
mostly a wind loss from tailings.
Due to the wind loss from tailings the cadmium emissions from
sources of mining are estimated at 0.2 pounds per ton of
cadmium mined. This would give a total figure of 530 pounds
of cadmium emissions to the atmosphere for 1968.
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METALLURGICAL PROCESSING
In the United States primary cadmium is recovered principally
from foreign and domestic zinc concentrates processed at zinc
smelters and refineries. Eight of the fourteen domestic zinc
plants that produce primary zinc have the cadmium purification
facilities required to produce cadmium metal. These eight
plants normally produce about 75 percent of the domestic
primary cadmium. The other 25 percent is produced by two
cadmium plants that receive their feedstock from other locations.
At one of the plants feedstock is principally cadmium flue dust
imported from Mexico. At the other plant the feedstock is
cadmium bearing zinc ore from which most of the cadmium is
recovered before the ore is shipped elsewhere for zinc recovery.
Processing procedures followed at each zinc smelter or refinery
are different and the efficiency of dust collection varies from
plant to plant, even though many of the plants are of the same
general type. This difference is accounted for by the type, age,
condition, and arrangement of dust collecting equipment and the
number of times the fume is recycled.
Most of the atmospheric emissions occur during the roasting
and sintering of zinc concentrates as impurities are removed.
Cadmium is volatilized and condensed to be collected as dust
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in the bag houses and/or in the electrostatic precipitators.
From the standpoint of cadmium emissions to the atmosphere,
the zinc metallurgical processing plants are the most important.
Lead and copper smelters also process concentrates containing
cadmium and even though the cadmium content is low, the losses
are relatively high. The concentration of cadmium in the fume
from roasting and smelting operations is low; thus the fume is
recycled many times to increase its cadmium content to 8 or 10
percent before it is removed from the circuit for further processing,
Each time it is recycled some cadmium is lost to the atmosphere
so the actual percentage of cadmium lost is rather high. Re-
cycling of fume is practiced to some extent in nearly every
plant, including zinc smelters.
Very few operators were found who actually knew the particle
size of the emissions. The operators who had collected samples
of emissions advised that the emissions vary in size from 4 to
8 microns. This does not necessarily represent the size of the
actual cadmium particle. The emissions are composed of cad-
mium and other materials. Cadmium oxide dust, as it leaves
the process, is in a very finely divided state. It is actually a
fume, and the minute particles may act as a nucleus to form a
larger particle or other material may act as a nucleus to catch
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the cadmium fume. The cadmium contained in the fume may be
in the form of cadmium oxide. It may be combined with sulphur,
iron, or some other element. Field and lab testing were not a
part of this contract and operators were not aware of the exact
analysis of the emissions, but always referred to it as cadmium
oxide or cadmium sulfate.
All zinc and lead smelters that were visited during this study
were equipped with electrostatic precipitators and/or bag filters.
It is understood that all such smelters in the United States are
equipped with similar emission control equipment. Some systems
operate more efficiently than others due to the type of process
and to the management.
During 1968 cadmium emissions to the atmosphere resulting from
metallurgical processing of cadmium-bearing ores totaled more
than 2.1 million pounds. This estimate is based on material
balance data obtained from processing companies during field
trips to lead, zinc, copper, and cadmium plants. The results of
stack tests were not available.
Cadmium emissions factors based on data obtained are as follows:
Pounds Cd Emissions
Type Of Plant per ton Cd processed
Range Average
Cadmium Recovery Unit 20-30 25
Zinc Plant (not including Cadmium unit) 220-560 284
Lead & Copper Plant 1200-1400 1310
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REPROCESSING
The reprocessing companies contacted during field trips, with-
out exception, reported that cadmium was too expensive to be
wasted, and their emissions were insignificant.
From data received from reprocessing companies, the estimated
cadmium emissions to the atmosphere for the year 1968 -
33,528 pounds.
ELECTROPLATING
Electroplating with cadmium is a process consisting of setting
up articles to be coated as cathodes in an electrolytic bath,
the anode being metallic cadmium. As direct current electricity
is passed through the bath, ions from the electrolyte are de-
posited on the objects to be coated and an equivalent amount of
cadmium is dissolved at the anode.
Virtually all commercial plating is from cyanide baths although
cadmium can be deposited from acid baths. Nearly every bath
characteristic of importance favors the cyanide-cadmium bath
because of its ability to give a dense, fine grained deposit,
the excellent covering power, and the good, plate distribution on
recessed articles.
None of the electrolytic processes operate at one hundred per-
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cent efficiency, and some of the electric energy decomposes
water in the bath, evolving hydrogen and oxygen gases. If the
efficiency is low and the rate of gassing high, the constituents
of the electrolyte are discharged to the atmosphere. Fortunately
from the standpoint of air pollution, the electrolytic efficiency
in cadmium plating is near one hundred percent.
Although most cadmium plating is by electro-deposition, a small
amount of special purpose plating is by vacuum evaporation. For
this process a special vacuum vessel is required. After the cad-
mium and the articles to be plated are placed in the vessel, the
vessel is sealed and evacuated. Electric heat is applied to the
cadmium which soon vaporizes and deposits on the articles to
be coated.
During the search for sources of atmospheric emissions, many
in the plating industry were contacted concerning their use of
cadmium. They reported as follows:
1 - Low gassing rates
2 - Agitation of the electrolyte not required
3 - Masks for workmen not required
4 - Air pollution control equipment not required
5 - No cadmium emissions to the atmosphere
During 1968 the cadmium emissions to the atmosphere as the
result of electroplating operations were negligible.
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PIGMENTS
Cadmium sulfide, also known as cadmium yellow, may Ifc pre-
pared in several ways. One process is by heating cadmium
oxide with sulfur and another is to disolve cadmium oxide in
sulfuric acid and then precipitate the sulfide from the solution
with hydrogen sulfide. Two other methods also include a pre-
cipitation step, and it is interesting to note that the color of the
sulfide precipitated depends on the particle size. The color is
light yellow when the cadmium sulfide is precipitated from a
cold solution of low cadmium content and deep orange when it
is precipitated from hot acid solutions with hydrogen sulfide.
Cadmium lithopone is prepared by mixing solutions of cadmium
sulfate and barium sulfide which yields cadmium sulfide and
barium sulfate. This is filtered and calcined in a reducing atmos-
phere to give it a uniform color. The shade or color of the product
depends on the calcining process. The orange shades are obtained
when the product is not calcined, but simply dried.
Cadmium sulfoselenide pigments are prepared by adding selenium
to a solution of barium sulfide or nitrate, reacting the solution
with cadmium sulfate, and calcining with excess sulfur to remove
unreacted selenium. This process and many others in commercial
use are similar regarding the requirement for a heating or calcining
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step.
All major compounders of pigments were contacted during this
study and pertinent information was obtained including: the
quantity of cadmium used, the type of air pollution control
equipment in service, general information concerning the end
use of products. None maintained cadmium emissions records
but their estimates averaged 15 pounds cadmium emissions per
ton of cadmium processed. All reported that they used bag
filters for emission control.
The cadmium atmospheric emissions for 1968 would be 21,000
pounds.
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PLASTICS
Barium-cadmium stabilizers are now used extensively in the making
of plastics so its compounding process is important from the stand-
point of cadmium emissions. It is reported that the weight loss of
cadmium to the atmosphere is very low during the actual wet pro-
cessing as the cadmium oxide is reacted with fatty acids to form
cadmium soaps. The oxide is charged into the reactor after the
fatty acids and the vessel is then sealed; however there is some
loss when handling the cadmium oxide prior to and during the time
it is introduced into the reactor.
The compounding of cadmium-containing stabilizers can be a sig-
nificant source of cadmium emissions to the atmosphere. At one
facility visited during a field trip permission to view the operations
was denied; however from the outside of the plant emissions of
particulate matter were quite noticeable. At another plant where
operations were observed, no emissions were visible, and the
inside of that plant was relatively clean. There were bag filters
and the emissions were reported to be less than one-half of one
percent.
In this study the emissions reported are based on the manufactur-
er's estimates, and the emissions factor is 6 pounds of cadmium
emissions per ton of cadmium processed. All manufacturers of
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stabilizers reported that they use bag filters for emission control.
For 1968 the estimated cadmium emissions from the manufacture
of plastic stabilizers is 6000 pounds.
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ALLOYS
In the United States about 160 companies produce alloys that con-
tain cadmium, and the quantity used by each company varies from
1000 pounds to 150,000 pounds per year. Products produced are
low-melting point solders and brazing alloys that are used by
home-owner as well as by manufacturers of appliances and var-
ious types of equipment. One common use is in the manufacture
of condensers for air conditioners. Another use is in the alloy-
ing of copper which is used chiefly for automobile radiators.
Several other reported reprocessing operations of cadmium in
alloys were explored - use in bearings, and in copper for elec-
trical transmission lines. More than one million pounds annu-
ally were used in bearings during World War II but currently the
requirement for this purpose is relatively small. Electrical cable
manufacturers were contacted but none reported using cadmium
during 1968.
Emissions are based on the estimates obtained from manufacturers.
The emissions factor is 10 pounds cadmium per ton of cadmium
processed. In 1968 the cadmium emissions to the atmosphere
were 5000 pounds.
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BATTERIES
In the nickel-cadmium battery of the sintered-plate type, the
grids of both positive and negative plates consist of sintered
carbonyl nickel powder. The active material of the positive
plate, when charged is nickel oxide and that of the negative
plate is cadmium. Each plate of the core assembly has as its
foundation a screen of nickel-wire mesh. This screen is con-
verted into a sheet as nickel powder is deposited in its meshes
by a sintering process. It is the active material electrochem-
ically deposited within the pores of the sheets that distinguishes
between negative and positive plates.
Manufacturers report nickel emissions in the making of these
batteries to be greater than cadmium emissions which are only
2 pounds per ton of cadmium processed.
In 1968 the cadmium emissions to the atmosphere were 400
pounds.
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MISCELLANEOUS
Fungicides containing cadmium are used extensively on golf
courses, and to a lesser extent on lawns and ornamentals. One
such product, used principally on golf courses, is formulated
using cadmium oxide in solution with nitric acid and water.
Other formulators report the use of cadmium chloride or cadmium
carbonate in their solutions. All those contacted have stated
atmospheric losses of cadmium during formulation of fungicides
are negligible and that emission controls are not required.
The miscellaneous uses of cadmium include: the curing of rubber,
x-ray screens, cathode ray tubes, nuclear reactor components,
etc. Based on 2 pounds per ton of cadmium processed, their
emissions to the atmosphere are estimated at 1128 pounds.
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CONSUMPTIVE USES
Thousands of household and commercial products contain some
cadmium even though it was not purposely used in the manu-
facturing process.
Rubber Tires
Reported tests have shown the cadmium content of motor vehicle
tires of different brands to range from 20 to 90 ppm. _/ This cad-
mium content, no doubt, was due to the impurity in the zinc ox-
ide used as an accelerator. Nearly all industrial processes in-
volving zinc are subject to the presence of cadmium because both
metals derive from the same ores.
Zinc oxide used by the rubber industry in 1968 totaled 111,800
2 .
short tons, _/ and the cadmium content of the zinc oxide was
about 0. 05% or 111,800 pounds. The rubber used totaled 2,477,000
long tons; _/ a ratio of 20.2 pounds of cadmium per million pounds
of rubber which is in correlation with the test data reported above.
1 - Lagerwerff, J. V. and Specht, A. W. , Unpublished data,
United States Department of Agriculture, Beltsville, Md.
2 - Bureau of Mines Minerals Yearbook - 1968
3- Chemical & Engineering News, July 14, 1969, pp 46.
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Data concerning the wear and cadmium content of motor
vehicle tires
Vehicle miles during 1968 1,010,000,000,000
Number of tires per vehicle 4
Pounds of rubber per tire 14
Percent of rubber worn away
when tire is discarded 20
Percent of cadmium in the rubber .00202
Mileage life of tire 20,000
Based on the above figures, cadmium emitted by the wear of tires
was 11,400 pounds during 1968.
Motor Oil
Oil companies contacted during this study have stated that they
add no cadmium to motor oil; however test results show the average
cadmium content of five samples of motor oil as 0.48 ppm. _/
Vehicle miles during 1968 1,010,000,000,000
Oil burned - qts. per 500 mi. 1
Based on oil burned in the engine at the rate of one quart per 500
miles, cadmium emitted by the burning of oil in motor vehicles
during 1968 was 1820 pounds.
1 - Letter dated Ian. 16, 1970, Enrione, Richard E. to Spangler, C. V.,
Project Officer, Air Pollution Control Administration
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Fungicides
The fungicides containing cadmium are used mostly on golf courses
and applied in liquid form. Actual losses to the atmosphere during
spraying vary depending on spray particle size, wind velocity, type
of spray equipment, and other factors. Atmospheric losses of cad-
mium for 1968 are estimated at 500 pounds based on an average
loss of 2 percent during application of the fungicides.
Fertilizers
It has been reported that some fertilizers contain cadmium, and
that fertilized soils contain more cadmium than unfertilized soils.
During this study the large fertilizer companies were contacted,
and without exception, they reported no cadmium used in fertili-
zers. It is known that the cadmium content of superphosphate is
about 110 ppm, _/ and this may be the reported source of cadmium
in fertilizers.
During 1968 the production of superphosphate in the United States
2
totaled 4,148,829 short tons._/ Cadmium emissions resulting
from the use of fertilizers that contain superphosphate are 910
pounds based on an average loss of 0.1 percent.
1 - Caro, J. H., Superphosphate: Its History, Chemistry, and Manu-
facture, U. S. Department of Agriculture and TVA, pp-273-305.
2 - Current Industry Reports - M Series: M28D(68)-12 U. S. Dept.
of Commerce, Bureau of Census.
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-39-
IN GENERATION AND OTHER DISPOSAL
Numerous references that list the major emission sources of cadmium
include the metal industries engaged in extraction and refining, but
few include or make reference to the emissions that may occur with
disposal of scrap.
From 1954 through 1968 the annual use of cadmium in the United States
ranged from 7.5 million to 14.8 million pounds; a total of 165 million
pounds used during 15 years. (Table V) In the same period the re-
covery of secondary cadmium from scrap averaged less than 500,000
pounds per year. _/ More than 95 percent of the 165 million pounds
of cadmium that was placed in use is still in use or has been disposed
of as waste.
Plated Metal
For fifty years the largest use of cadmium in the United States has
been for electroplating; mostly for plating iron and steel. It has
been reported that cadmium consumed in electroplating in 1955 was
o
about 6.2 million pounds, _/ while steel produced that year totaled
3
117 million tons: _/ a ratio of 0.053 pounds cadmium used in electro-
1 - Bureau of Mines Minerals Yearbooks - 1952 through 1968.
2 - Mentch, R. L. et al, Cadmium - A Materials Survey, Info.
Circ. 7881, Bureau of Mines, 1958, pp 13.
3 - Metal Statistics 1969, The American Metal Market Company
Somerset, New Jersey.
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TABLE V
APPARENT CONSUMPTION OF CADMIUM
Year
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
Total
Pounds
(thousands)
7499
10684
12711
10966
8242
11589
10126
10184
12146
11482
9365
10431
14780
11561
13328
165094
TABLE VI
ZINC USED IN GALVANIZING - STEEL PRODUCTION
(Short Tons-Thousands)
Year
1961
1962
1963
1964
1965
1966
1967
1968
Zinc Used In
Galvanizing
382
389
420
456
482
474
459
459
3521
Steel
Production
98014
98328
109261
127076
131462
134070
126920
131098
956229
Pounds of Zinc Used In Galvanizing per ton of steel produced - 7.4
Metal Statistics - 1969
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plating per ton of steel produced. In 1963, cadmium consumed in
electroplating was reported as 6.3 to 6.9 million pounds, _/ and
steel produced as 109 million tons: f/ a ratio of 0.058 to 0.063
pounds of cadmium per ton of steel. In this report a ratio of 0.05
pounds of cadmium per ton of steel is used to calculate the amount
of cadmium in steel due to cadmium plating.
Galvanized Metal
Steel scrap also contains galvanized metal and the zinc used in
galvanizing averages 7.4 pounds per ton of steel produced (Table
VI). Since the cadmium content in zinc (for galvanizing) is re-
ported to average about 0.04 percent, the cadmium content in
steel due to zinc galvanizing is about 0.003 pounds per ton of
steel.
Steel producing companies contacted have indicated that scrap steel
they use contains nickel, chromium, copper, manganese, cadmium,
zinc and other metals, and that nickel, chromium, and copper will
not be emitted to the atmosphere; that manganese will stay in the
slag; that other metals will be released as vapors. There are no
records showing the cadmium content of the scrap.
1 - Schroeder, H. J., Cadmium - Mineral Facts and Problems;
Bureau of Mines Bulletin 630, 1965, pp 165
2 - Metal Statistics 1969, The American Metal Market Co. ,
Somerset, New Jersey.
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The 38.5 million tons of steel scrap purchased by the steel industry
in 1968_/ is estimated to contain 2.04 million pounds of cadmium
based on cadmium plated and zinc galvanized steel in the scrap.
Cadmium emissions to the atmosphere during steelmaking are esti-
mated at 2.0 million pounds or 0.0152 pounds of cadmium per ton
of steel produced.
Auto Radiators
Cadmium is used to harden copper and in automobile radiators the
o
copper contains about 0.2 percent cadmium. _/ During 1968 auto
radiators accounted for 64,394 short tons of copper scrap consumed
by secondary producers. _/ According to information obtained during
this study there is no recovery of cadmium by secondary producers
of copper and cadmium contained in the scrap is released to the
atmosphere during copper recovery operations.
Cadmium emissions to the atmosphere during recovery of copper
from scrapped auto radiators are estimated at 250,000 pounds.
1 - Metal Statistics 1969, The American Metal Market Co. , Somerset,
New Jersey
2 - Trends in the Usage of Cadmium, Materials Advisory Board,
Publication MAB-255
3 - Bureau of Mines Minerals Yearbook - 1968.
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Other
Solid waste includes many different kinds of articles that contain
cadmium. Plastic bottles, auto seat covers, furniture, floor
coverings, and numerous items made of polyvinyl chloride, other
than food containers, are likely to contain cadmium as a coloring
agent and as a stabilizer. There were millions of tons of waste
discarded in 1968 that contained cadmium in plastics, pigments
and miscellaneous items. These items were using cadmium
produced mostly prior to 1968.
During the past ten years cadmium used in plastics and pigments
has averaged about 2.3 million pounds annually, and miscellaneous
uses during the same period has averaged about 0.9 million pounds.
It is estimated that 40 percent of these annual averages were con-
tained in solid waste in 1968, and that 15 percent of the solid
waste was incinerated. Based on these estimates, cadmium emissions
to the atmosphere from incineration were 190,000 pounds.
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APPENDIX A
PLANTS PRODUCING CADMIUM, LEAD AND ZINC
COMPANY
American Smelting & Refining Company
American Zinc Company
Anaconda Company
Blackwell Zinc Company
The Bunker Hill Company
Eagle - Pitcher Industries, Inc.
International Smelting & Refining Company
Matthiessen & Hegeler Zinc Co.
Missouri Lead Operating Co.
National Zinc Company, Inc.
New Jersey Zinc Company
St. Joseph Lead Company
United Refining & Smelting Co.
U. S. Smelting Lead Refinery, Inc.
U. S. Smelting, Refining and Mining Co.
Bureau of Mines Minerals Yearbook - 1968
W U. S. GOVERNMENT PRINTING OFFICE: 1B73 746771/4185
LOCATION
Amarillo, Texas
Corpus Christi, Tex.
Denver, Colo.
East Helena, Mont.
El Paso, Texas
Glover, Missouri
Omaha, Nebr.
Shelby, California
Dumas, Texas
East St. Louis, 111.
Anaconda, Mont.
Great Falls, Mont.
Blackwell, Okla.
Kellogg, Idaho
Galena, Ks.
Henryetta, Okla.
Tooele, Utah
Meadow brook, W. Va,
Boss, Mo.
Bartlesville, Okla.
Depue, 111.
Palmerton, Pa.
Josephtown, Pa.
Herculaneum, Mo.
Franklin Park, 111
East Chicago, Ind.
Midvale, Utah
METAL PRODUCE
Zn
Zn - Cd
Cd
Pb
Pb
Pb
Pb
Pb
Zn
Zn - Cd
Zn
Zn - Cd
Zn - Cd
Zn - Cd - Pb
Cd
Zn
Pb
Zn
Pb
Zn - Cd
Zn
Zn - Cd
Zn - Cd
Pb
Cd
Pb
Pb
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BIBLIOGRAPHIC DATA
SHEET
1. Report No.
APTD-68
4. Title and Subtitle
National Inventory of Sources and Emissions: Cadmium - 1968
3. Recipient's Accession No.
PB 192-250
5. Report Date
February 1970'
6.
7. Author(s)
W. E. Davis
8. Performing Organization Rept.
No.
9. Performing Organization Name and Address
W. E. Davis § Associates
9726 Sagamore Road
Leawood, Kansas
10. Project/Task/Work Unit No.
11. Contract/Grant No.
CPA 22-69-131
12. Sponsoring Organization Name and Address
Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, N.C. 27711
13. Type of Report & Period
Covered
Final
1968
14.
15. Supplementary Notes
16. Abstracts
The inventory of atmospheric emissions has been prepared to provide reliable informatioi
regarding the nature, magnitude, and extent of the emissions of cadmium in the United
States for the year 1968. Bascground information concerning the basic characteristics
of the cadmium industry has been assembled and included. Process descriptions are
given, but they are brief, and are limited to the areas that are closely related to
existing or potential atmospheric losses of the pollutant. The cadmium emissions and
emissions factors that are presented are based on the summation of the information
obtained from production companies that represent approximately forty percent of the
total production, and the reprocessing companies that handle about forty-five percent
of the cadmium used in consumer products. Emissions control equipment is in use at all
the production facilities that were visited. It is a part of the process system for
the recovery of zinc, and is not specifically for the control of cadmium emissions to
the atmosphere. Cadmium emigsinns and emiQ^inrK; -FartnrQ a-rp- rn-ncirlovprl tn Ko rooer.-ncilK'i-
17. Key Words and Document Analysis. 17o. Descriptors
Atmospheric emissions
Pollutant
Emission factors
accurate.
17b. Identifiers/Open-Ended Terms
Cadmium
Cadmium Emissions
Cadmium emission factors
Cadmium industry
17e. COSATI Fie Id/Group
18. Availability Statement
Unlimited
19. Security Class (This
Report)
UNCLASSIFIED
20. Security Class (This
Page
UNCLASSIFIED
21- No. of Pages
51
22. Price
$3.00
FORM NTIS-33 (REV. 3-72)
USCOMM-DC 14852-P72
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