APTD-1543
EMISSION STUDY
OF INDUSTRIAL SOURCES
OF LEAD AIR POLLUTANTS
1970
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 277
,
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APTD-1543
EMISSION STUDY
OF INDUSTRIAL SOURCES
OF LEAD AIR POLLUTANTS
1970
by
W. E. Davis
W. E. Davis £ Associates
9726 Sagamore Road
Leawood, Kansas
Contract No. 68-02-0271
t
EPA Project Officer: David L. Anderson
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
April 1973
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This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - as supplies permit - from the
Air Pollution Technical Information Center, Environmental Protection
Agency, Research Triangle Park, North Carolina 27711, or from the
National Technical Information Service, 5285 Port Royal Road, Spring-
field, Virginia 22151.
This report was furnished to the Environmental Protection Agency by
W. E. Davis and Associates, Leawood, Kansas, in fulfillment of
Contract No. 68-02-0271. The contents of this report are reproduced
herein as received from W. E. Davis and Associates. 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 is representative of a high
degree of accuracy, References to this report should acknowledge
the fact that this is an es^ imate only.
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PREFACE
This report was prepared by W. E. Davis & Associates pur-
suant to Contract No. 68-02-0271 with the Environmental
Protection Agency, Office of Air Programs.
The inventory of atmospheric emissions has been prepared
to provide reliable information regarding the natures mag-
nitude, and extent of lead emissions from industrial sources
in the United States for the year 1970.
Background information concerning the basic characteristics
of the lead industry has been assembled and included. Pro-
cess 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 all of the primary produc-
ing companies and about seventy-five percent of the large
industrial users of lead in each emission source group to
obtain the required information. It was known that published
data concerning the atmospheric emissions of lead were vir-
tually nonexistent, and contacts with industry ascertained
m
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that atmospheric emissions were seldom a matter of record.
The lead emissions and emission factors that are presented
are based on the summation of data obtained from industrial
sources. Additional information was acquired during field
trips to inspect air pollution control equipment and observe
processing operations.
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 lead industry for their contributions.
We wish to express our gratitude for the assistance of the
various societies and associations, and to the many branches
of the Federal, State, and Local Governments.
Our express thanks to Mr. C. V. Spangler, Project Officer,
EPA, Office of Air Programs, Research Triangle Park,
N. C. , for his helpful guidance.
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CONTENTS
PREFACE
ACKNOWLEDGEMENTS
INTRODUCTION 1
SUMMARY 3
Emissions by Source 3
Emissions by States 4
Emission Factors ' 5
SOURCES OF LEAD 8
MATERIAL FLOW THROUGH THE ECONOMY .... H
Chart „ 12
USES AND EMISSIONS .OF LEAD
Mining and Milling 14
Metallurgical Industries 18
Primary Lead 18
Primary Copper 27
Primary Zinc 29
Secondary Lead ........ .. 33
Lead Oxide 40
Consumer Product Manufacturing 45
Storage Batteries 46
Gasoline Additives 54
Pigments 62
Ammunition 73
Solder 77
Cable Covering 82
Type Metal 85
Brass and Bronze 89
Bearing Metals 92
Metallic Lead Products 95
Miscellaneous < 97
vii
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OTHER SOURCES OF LEAD EMISSIONS
Waste Incineration 99
Waste Oil 99
Municipal Incineration 101
Sewage and Sludge Incineration 103
Coal 105
Oil 109
Iron and Steel '..... 112
Grey Iron Foundries '115
Ferroalloys 117
Cement Plants 119
UPDATING OF EMISSION ESTIMATES . 121
Vlll
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TABLES
Table I Emissions by Source 3
Table II Emissions by States t . . 4
Table III Emission Factors 6
Table IV Brass-Melting Furnace and
Baghouse Collector Data 90
Table V Lead Content of Coal Mined in
the United States 106,
FIGURES
Figure I Material Flow Through the Economy ... 12
Figure II Lead Mining and Mill-ing Flow Diagram . . 15
Figure III Lead Smelter-Refinery Flow Diagram . . 21
Figure IV Storage Battery Manufacture
Flow Diagram 48
Figure V TEL Batch Plant Flow Diagram
Sodium-Lead Alloy Pi ocess . ........ 56
Figure VI TEL-TML Plant Flow Diagram
Electrolytic Process 59
ix
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INTRODUCTIQN
The primary objective of this study was to investigate and
determine the nature, magnitude, and extent of industrial
lead emissions to the atmosphere in the United States during
the year 1970. The emission estimates, the particle size
distribution, the chemical analyses, and the air pollution
control equipment data presented herein represent a broad
spectrum of information from numerous sources.
The many industrial processes and activities that generate
significant lead emissions to the atmosphere are described
in this report so that the reader may have the opportunity to
understand why there are such great variations in the mag-
nitude of emissions from different sources. Information on
the efficiency and effectiveness of various air pollution.con-
trols is included and compared,
It should be pointed out that this document does not include
estimates of lead emissions from natural sources, emissions
due. to the burning of leaded gasoline, or others not directly
related to industrial activities sucn as resuspension of lead
by moving vehicles, burning of lead-painted surfaces, welding
of lead-painted steel, dusting of lead-containing items subject
to weathering, and incineration of leaded plastics.
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SUMMARY
The flow of lead in the United States has been traced and
charted for the year 1970 (Figure I). The consumption was
lt 361, 000 tons, while primary, and secondary production
totaled 667, 000 and 597, 000 tons, respectively. Approxi-
mately, 20 percent of the primary lead was recovered from
foreign ore.
Emissions to the atmosphere during the year were 18,050
tons (Table I). About 18 percent of the emissions resulted
from the burning of waste oil, 13 percent from municipal in-
cineration* 13 percent from grey iron foundries, 11 percent
from the processing of gasoline additives, 9 percent from the
production of.primary lead, 9 percent from copper smelting,
and 8 percent from the production of iron and steel. The
combustion of coal, the manufacture of storage batteries,
and the production of portland cement were also significant
emission sources.
Emission estimates for mining, production of primary and
secondary lead, lead oxide processing, and the manufacture
of end use products are based on unpublished data obtained
from industrial sources.
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TABLE I
Source Category
Mining and Milling
Metallurgical Industries
^MISSIONS .BY SOURCE
1970
Source Group
Primary Lead
Primary Copper
Primary Zinc
Secondary Lead
Lead Oxide
Cpnsui&er Product Manufacturing
Storage Batteries
Gasoline Additives
Figments
Solder
Cable Covering
Type Metal
Brass and Bronze
Metallic Lead Products
Other Emission Sources
Emissions - Tons
60
1,700
1,700
240
220
480
,^00
210
110
50
200
40
90
Waste Incineration
Waste Oil 3, 200
Municipal Incineration 2, 400
Sewage & Sludge Incineration 200
Coal 650
Oil 90
Iron & Steel 1, 500
Grey Iron Foundries 2, 300
FerroaV 70
C'.-men 500
3, 860
140
3,080
10,910
Emissions
%
0.3
21.4
0. 8
17.0
60.5
18
100, 0
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TABLE n
EMISSIONS BY STATES
State
Alabama
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Tons
273
1,012
160
1, 123
103
154
26
330
367
1,066
882
597
137
158
164
1, 112
50
193
279
702
171
122
643
320
State
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
TOTAL
Tons
73
126
35
797
167
1,044
261
30
829
165
120
1,199
45
134
35
232
1,374
475
22
242
164
99
223
15
18,050
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EMISSION FACTORS
»
The emission factors presented herein are the best currently
available. They were determined through a combination of
methods consisting of: (1) directfobservation of emission
data and other related plant processing and engineering data;
(2) estimates based on information obtained from literature,
plant operators, and others knowledgeable in the field; (3)
calculations based on experience and personal knowledge of
metallurgical processing operations; and, (4) specific ana-
lytical results where available.
The basic data used to calculate the emission factors are
contained in the files of the Contractor.
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TABLE HI
Source
Mining and Milling
Metallurgical Industries
Primary Lead Production
Primary Copper Production
Primary Zinc Production
Secondary Lead Production
Lead Oxide Processing
Consumer Product Manufacturing
Storage Batteries
Storage Batteries
Gasoline Additives
Solder
Cable Covering
Type Metal
Brass and Bronze
EMISSION FACTORS
Factor
0. 2 Ib/ton lead mined (controlled)
5. 0 Ib/ton of product (controlled)
0. 6 Ib/ton of Cu concentrates (controlled)
0. 3 Ib/ton of Zn concentrates (controlled)
0. 7 Ib/ton of product (controlled)
0. 7 Ib/ton of lead oxide (controlled)
8. 0 Ib/ton of lead processed (uncontrolled)
1.3 Ib7ton of lead-pr-QC-efr&ed (controlled)
14. 0 Ib/ton of lead processed (controlled)
3. 0 Ib/ton of lead processed (controlled)
2. 0 Ib/ton of lead processed (controlled)
17. 0 Ib/ton of lead processed (controlled)
4. 0 Ib/ton of lead processed (controlled)
Qualifier
Plant visit
Questionnaires
Estimate
Estimate
Questionnaires
Questionnaires
.Questionnaires
Questionnaires
Questionnaires
Estimate
Que s ti onnair e s
Questionnaires
Questionnaires
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Other Emission Sources
Waste Oil. Combustion
Municipal Incineration
Sewage and Sludge Incineration
Coal Combustion
Distillate Oil Combustion
Residual Oil Combustion
Steel Production
Open-Hearth
Basic Oxygen
Electric Arc
Grey Iron Foundries
Cement Production
Pigments
Ferroalloys
Silicomariganese
Electric Furnace
Ferromanganese
Electric Furnace
Blast Furnace
0. 04 Ib/bbl of oil burned (controlled)
0. 2 Ib/ton of charge (controlled)
0. 6 Ib/ton of charge (uncontrolled)
Estimate
Stack sampling
Stack sampling
2.2 lb/1,000 tons of coal burned (controlled) Estimate
0. 1 lb/1, 000 bbls of oil burned .(uncontrolled) Stack sampling
0. 04 Ib/bbl of oil burned (uncontrolled) Stack sampling
0. 14 Ib/ton of steel (uncontrolled)
0. 18 Ib/ton of steel (uncontrolled)
0. 18 Ib/ton of steel (uncontrolled)
0. 3 Ib/ton of iron (uncontrolled)
25 lb/1, 000 bbl of cement production
(uncontrolled)
Atomic absorption
Atomic absorption
Atomic, absorption
Estimate
Stack sampling
10 Ib/ton of lead processed (uncontrolled) Questionnaires
0.9 Ib/ton of product (uncontrolled) Estimate
0.4 Ib/ton of product (uncontrolled) Estimate
4 Ib/ton of product (uncontrolled) Estimate
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SOURCES OF LEAD
Lead (Pb) is a heavy, soft, bluish-gray, corrosion-resistant
metal that is widely distributed in the earth's crust in the
form of its various minerals. It otcurs commonly as galena
(lead sulfide, PbS), cerrusite (lead carbonate, PbCO-j), and
anglesite (lead sulfate, PbSO^). In the United States the most
abundant lead mineral currently mined is galena and it is
often associated with the zinc mineral.,sphalerite, commonly
called zinc blende.
The ratio in which lead and zinc minerals are found in com-
bination varies over a wide range. In Missouri, tKe leading
lead-producing state, the ratio is in the order of 90 percent
lead to 10 percent zinc. In the eastern states the situation
is quite different; the ores there contain only a small amount
of lead. Ores found in the western states contain approxi-
mately equal parts of the two minerals.
In. the United States the supply of lead during 1970 was de-
rived from four sources: secondary lead reclaimed from
new and old scrap, primary lead produced from domestic
ores, imported metal, and primary lead recovered: from
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-9-
foreign ores. Secondary lead is very important in the domestic
supply pattern. In fact, since 1945 the quantity of lead from
this source has exceeded domestic mine production. Battery
»
plateSj cable covering, pipe, and sheet lead are the principal
scrap materials that are reclaimed for remelting and refining.
During 1970 a large part of the domestic lead ore was pro-
duced in .the southeastern part of Missouri. The quantity of
ore mined in the state totaled nearly 9 million tons and the
recoverable lead content was reported at 421, 764 tons /,
or approximately 74 percent of the domestic production.
The recoverable lead content of ore produced in Idahos Utah,-
and Colorado was 6l,211 tons, 45,377 tons, and 21, 855 tons,
respectively. Other states producing less than 6, 800 tons
included.Arizona, California, Kansas, Montana., Nevada, New
Mexico, New York, Virginia, Washington, and Wisconsin.
Mine production of lead in the world .during 1970 was nearly
3. 8 million tons of which nearly 32 percent was produced in
North America, over 7 percent in South America, 31 percent
in Europe, about 6 percent in Africa,, nearly 9 percent in
1- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
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-10-
Asia, and more than 13 percent in Australia _/. There
were 3 producing countries in North America, 2 in Central
America, 6 in South America, 20 in Europe, 6 in Africa,
and 11 in Asia. Imports of metal and ore into the United
States were principally from Australia, Canada, Honduras,
Mexico, Peru, Republic of South Africa, and Yugoslavia.
1- Minerals Yearbook; Bureau, of Mines; 1970 Preprint.
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MATERIAL FLOW THROUGH THE ECONOMY
The consumption of lead in the United States during 1970 was
1, 360, 552 tons /, a decline of about 2 percent from the
previous year. Smaller quantities were required in nearly
every phase of industry except for motor vehicles, where
approximately 2 percent more was used for production of
storage batteries and gasoline antiknock additives.
The sources of supply were principally as follows: primary
lead, 528, 086 tons produced from domestic ores and 138, 644
tons from foreign ores; secondary lead, 597, 3°>0 tons re-
.covered from salvage materials; and imported metal, 244,623
tons / as shown in Figure I. Most of the antimonial leads
solder, and type metals were produced as secondary
metal.
The largest consumption of lead was in storage batteries.
About 44 percent of the total supply was utilized for this pur-
pose. The second largest use, slightly more than 20 percent,
was in the production of gasoline antiknock additives. . Other
1- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
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LEAD
MATERIAL, FLOW THROUGH THE ECONOMY - 1970
(1, 000 Short Tons)
SOURCES USES
528 ^, lUTNTNf-
DOMESTIC ORE BENEFACTION
1
139
FOREIGN ORE * ^>MEL111MU
k
REFINING " ~ *"
12 r
ANTIMONIAL LEAD
12 »
GOVERNMENT STOCK
98
" INDUSTRY STOCK
245 ^
METAL IMPORTS
- 8
EXPORTS
66
~* UNACCOUNTED
597 p.
SECONDARY LEAD
A
1 ^.^ __.
1,361
593
STORAGE BATTERIES
279
GASOLINE ADDITIVES
99 -
PIGMENTS
73
AMMUNITION
70"
SOLDER
51
CABLE COVERING
24
TYPE METAL
19
BRASS AND BRONZE
122
METALLIC 'PRODUCTS
16
BEARING METALS
15
MISCELLANEOUS
w CONSUMER
1
1
1
1
1
1
i
1
1
1
r
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specific products requiring from 25, 000 to 100, 000 tons
each were pigments, ammunition, solder, cable covering,
and caulking lead.. Categories of use requiring less than
25, 000 tons included type metal, sheet lead, brass and
bronze, piping materials, bearing metals, weights and bal-
lasts, collapsible tubes, castings, foil, terne metal, galva-
nizing, annealing, and glass.
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USES AND EMISSIONS OF LEAD
MINING AND MILLING
The lead ores produced from underground mines in Crawford,
Iron, Reynolds, St. Francois, and Washington counties in the
southeastern part of Missouri accounted for about 75 percent
of the lead recovered from domestic ores during 1970. The
average lead content of these ores was 4. 8 percent, and the
zinc concentration was 0. 6 percent _/.
Even though the practices followed at different mining loca-
tions vary somewhat, the basic operations that are performed
are essentially the same. In the typical mine, percussive
drilling machines and metallized explosives are used to loosen
and bjreak the ore. The operations that follow include ore
loading, moving, crushings and hoisting as shown in Figure II.
After the ore reaches the surface the size reduction process
continues as the material passes through primary screening,
secondary crushing, secondary screening, tertiary crushing,
and milling. At this point the ore is in a very finely divided
1- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
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TYPICAL FLOW DIAGRAM
LEAD MINING AND MILLING
Drilling & Blasting
I
Primary Crusher
I
Ore Hoist
I Conveyor Si Feeder |
Screen
I
I Secondary Crusher
j Convey
or & Feeder
Screen
I Conveyor
I "
Tertiary Crusher
Conveyor & Feederj
1
| Rod Mill
Cyclone Separator I
Lead Rougher
^^^^^^^^^^••^^•^••^^^•Vi^BBJfc
Tails to
Zinc Circuit
j Lead Cleaner j
Cyclone Separator
Conditioner
Drum Filter
j Conveyor 1
• J . 1
Shipping
Figure II
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state and is ready for separation by selective flotation.
First the lead concentrates are separated in the lead flota-
tion rougher and processed in a cleaner, a thickener, and a
filter as they are prepared for shipment to the smelter. The
zinc concentrates are separated in the zinc flotation rougher,
and the final step is to forward tailings to the tailings pond.
F-rom the standpoint of emissions to the atmosphere, the
principal losses during mining and milling operations are
those that occur due to or,e handling, screening, crushing,
and wind loss from outdoor storage of concentrates. During
grinding and flotation, the ore is wet and atmospheric emis-
sions are negligible.
While this study was in progress, many lead mining com-
panies were contacted regarding their operations and the
lead emissions that occur prior to the time concentrates are
shipped to the smelter. Records and test data on lead emis-
sions were not available: however, numerous emission
sources were observed at each location'which was visited.
Lead emissions to the atmosphere from sources of mining
and milling are based on visual inspections and estimated
by the Contractor at 0. 2 pound per ton of lead mined. The
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-.17-
recoverable lead content of the ore mined in the United States
during 1970 was 571, 767 tons _/, and lead emissions to the
atmosphere were 60 tons.
It is estimated that each of the seven leading lead-producing
mines in the United States in 1970 produced ore containing
26, 000 tons or more of lead, and lead emissions from each
mine are potentially more than 20 pounds of lead per day.
Six of the mines are located in Missouri and one in Idaho.
1«> Minerals Yearbook; Bureau of Mines; 1970 Preprint.
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PRIMARY LEAD
In. the United States primary lead is recovered principally
from ores that contain varying amounts of galena (lead sul-
fide) and other minerals. The ore, as mined, also contains
a large quantity of nonvaluable material that is separated
from the minerals as the ore is upgraded during the flotation-
concentration process. These separations, however, are;not
complete and the lead concentrates carry with them many im-
purities that must be removed from the lead by means of
three basic pyrometallurgical processing steps. These basic
steps are essentially the same at all smelting and refining
facilities. They are sintering, blast furnacing, and refining.
Even though there are differences in the ores and concen-
trates, in a modern plant the major smelting and refining
equipment is of similar design. Lead sulfides are converted
to oxides of lead and sulfur at a relatively low temperature
in an updraft sintering machine. Then, the oxidized mater-
ial is reduced with coke at a high temperature in a blast
furnace to form lead bullion. During both these processing
steps, considerable quantities of waste gases containing lead
are discharged from, the equipment. After smelting, the
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lead bullion is transferred to the refining section where several
large open-refining kettles are utilized for the removal of cop-
per, silver, zinc, and other impurities.
The principal raw material in primary lead smelting is a lead
sulfide concentrate containing about 60 to 70 percent lead, 6
to 7 percent zinc, 13 to 18 percent sulfur, up to 5 percent
iron, and small quantities of lime, silica, silver, gold, ar-
senic, cadmium, selenium, tellurium, a.nd other substances.
The flux materials are silica, limestone, granulated slag,
and small amounts of scrap i.ron3 which, are used in the pro-
portions required to produce a free-running slag. The con-
centrates, coke, flux materials, and direct smelting ores
are received at the various smelters by railroad or by truck;
therefore, the methods of handling are somewhat different.
At one location the concentrates a.re received in hopper-
bottom trucks, transferred to hopper-bottom railroad cars,
weighed, sampled, a.nd dumped into large, covered, storage
bins. Wind losses of lead at this location are relatively
minor compared to those at another plant where concen-
trates are received both by truck and by rail, then stored
outdoors.
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As the raw materials are needed the concentrates, flux
materials, direct smelting ores, return sinter, and return
dusts are sized, measured, and mixed as required for the
feed to the sinter machine, as shown in-Figure III. During
these operations conveyors are used to transfer the mater-
ials and there are some lead emis.sions to the atmosphere.
The purpose of sintering is to remove sulfur and produce a
calcine that is strong, porous, and suitable for reduction
in the blast furnace. By roasting, the sulfide concentrates
are converted to oxides and the sulfur is reduced to an ac-
ceptable limit of approximately one percent. About 85 per-
cent of the sulfur in the feed is emitted with the off-gasrand
14 percent appears in the slag and other solid by-products.
As the lead and other metal sulfides are oxidized, heat is
generated and must be controlled to prevent excessive loss
of metals by volatilization. The temperature should be
held below 1,400 F.
The updraft sintering machine is a continuous conveyor with
•a windbox located above the moving grate-bar pallets.
There are two feeders in series. The first deposits a thin
layer of feed material which is ignited before it reaches the
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TYPICAL LEAD SMELTER-REFINERY
FLOW DIAGRAM
Concentrate
1
Flux
1
Dust
Coke
I I L
t
Sinter
Preparation
L, •
r ' •
Sinter
Machine
| Breaker |
Spil
Ro]
Ro
Ro]
1
I
ked
Lls
I
ss
Is
I
If
Charge
Preparation
L
i
Iron
r
Holding
Kettles
i
Dross
Kettles
i
r'
De silver ing
Kettles
i
,
De zinc ing
Kettles
i
r
Casting
Kettles
r
Blast
Furnace
Slag
Settler
\
Casting
I
Shipping
j Lead Bullion
Figure III
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-22-
point where the main layer is discharged from the second
feeder. Regulated updraft causes the burning to progress
from bottom to top, while gases, dust, and fume are drawn
through the upper windbox into ducts leading to the dust col-
lecting equipment.
The dust, including condensed fume, is recovered in bag
filters and recycled to the feed for the sintering machine.
It contains portions of all the elements present in the con-
centrates and is relatively rich in the more volatile metals.
Such condensation and recycle of fume provides an oppor-
tunity for recovering cadmium, which becomes more and
more concentrated during continued recycling. Usually
when the cadmium concentration reaches about 10 percent,
the dust is diverted to cadmium recovery facilities. After
dust recovery in the bag filters, the off~gas from the feed
end of the updraft sinter machine may be used as the feed
to a sulfuric acid plant. This is the current method at
some lead smelters.
In modern practice the smelting of lead is carried out in
blast furnaces in which the charge of sinter, limestone,
silica, and coke is heated and blown with air to effect the
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-23-
reduction of lead oxide to metallic lead. Complete combus-
tion of some of the coke supplies heat required for the prin-
cipal reaction and various others that take place. Heat, is
released as the carbon in the coke combines with the oxygen
in the air to form carbon dioxide. The remaining coke, the
carbon dioxide, and the heat react to form carbon monoxide
which is the reducing agent for the lead oxide.
The products generated in the blast furnace consist of four
liquids and the flue gas. The liquids, lead bullion, matte,
speiss, and slag are removed from the bottom of the furn-
ace and fed into a forehearth where the products separate
into layers before they are drained. The slag, containing
10 to 20 percent zinc and perhaps 2 percent lead, is usually
granulated in water and forwarded to the dump. The lead
bullion is transferred to the refinery. The matte and speiss,
containing 40 to 65 percent copper and 8 to 20 percent lead,
are of relatively minor value and usually are shipped to
other metallurgical plants. The gases, dusts, and fumes
emitted from the furnace are collected and cleaned in a bag
filter before the off-gas is released to the atmosphere.
The differences in lead smelting practice are principally
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-24-
due to variations of the impurities in the ores, the handling
of materials, and the degree of completeness of processing.
Certain metallic contaminants are reduced with the lead and
a subsequent refining process is required. Other contami-
nants affect the composition of the slags that are rejected
from the process.
At most lead smelters there is refining equipment that in-
cludes lead kettles for holding, drossing, desilvering, de-
zincing, and casting. Drossing is carried out by slowly melt.-
ing the bullion at controlled temperatures to remove trace
copper, tin, antimony, and arsenic. These contaminants
are preferentially oxidized and removed by skin^ming from
the molten lead. Lead from the reverberatory furnace is
transferred to desilvering kettles to which zinc is added to
form a crust containing the gold and silver. The crust is re-
moved for -further processing and the lead is transferred to
dezincing kettles where the residual zinc is removed byi dis-
tillation under vacuum. Usually at this stage the lead bullion
is treated with caustic for removal of the last traces of im-
purities. The refined lead is then tapped and cast.
From the standpoint of lead emissions to the atmosphere,
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-25-
there are many sources at lead smelters that should be con-
sidered in an emission inventory. Usually, however, the
metallurgical operations have been regarded as the most im-
portant; this is the area in which there is a limited amount
of published information. The other emission sources, often
overlooked and rarely included in emission estimates, are
materials transportation, handling, and storage. Relatively
large quantities of particulates, including lead, are emitted
from outside storage of concentrates and from railroad cars
or trucks carrying the concentrates from mining areas to
the smelter locations. Considerable dust with high lead con-
tent is transported by winds to areas far from the smelter
site.
Emissions from metallurgical operations originate at tlfe
sintering machine, the blast furnace., the reverberatory furn-
ace, and the refining kettles. During 1970, at smelters pro-
ducing more than 85 percent of the lead, the off-gases from
the sintering machines were cleaned either in a baghouse or
in gas-cleaning equipment near their acid plants. At one
plant these gases were cleaned in an electrostatic precipita-
tor. At all smelters the blast furnace gas was discharged
through a baghouse. At the refineries handling about 60
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-26-
percent of the lead, gases from the dross reverberatory
furnaces were directed through a. baghouse.
During this study all primary lead smelters and refineries
were contacted regarding their operations and their lead
emissions to the atmosphere. Information was obtained
from all smelters; however, it was incomplete in some
instances. Based on the information that was received, the
lead emissions to the atmosphere during 1970 due to the
smelting and refining of primary lead totaled 1, 700 tons,
including windblown losses estimated at 350 tons. Lead
emissions from the various metallurgical operations range
from less than one to 14 pounds per ton of lead produced,
averaging 4 pounds per tons while windblown losses average
approximately 1 pound per ton.
Emissions from the stacks were principally lead oxides. The
lead particle size of emissions from baghouses was reported
to be one micron or less, while those from concentrate stor-
age ranged upward to 100 microns.
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-27-
PRIMARY COPPER
In the United States the smelting of copper concentrates in-
cludes the processing steps of roastingj reverberatory furn-
acing, and converting. Copper sulfide is the principal-con-
stituent of the.ores and concentrates that are processed;
however, lesser quantities of lead sulfide and other minerals
are present. Lead emissions, therefore, may be expected
during copper smelting.
Roasting removes volatile impurities and oxidizes sulfur.
The reverberatory furnacing reduces copper and iron to
form copper matte. Next, the matte is placed in the con-
verter to remove the iron as iron oxide and as iron silicate
slag. After the slag is poured off, the remaining sulfur is
oxidized and blister copper remains. During.these process-
ing steps, oxides of sulfur, dusts, and fume are released
from the concentrates. Particulate emissions from roasters
are about 170 pounds per ton of copper produced and those
from converters average near 240 pounds per ton /.
1- McKee, Arther G. & Co. ; "Systems Study for Control of
Emissions PHmary Nonferrous Smelting Industry11; for
NAPCA; June, 1969.
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-28-
The following estimate for lead emissions from copper
smelting has been prepared.
1 - Approximately 6 million tons of copper concentrates
were processed in the United States during 1970 _/,
2 - The weighted average of lead in copper concentrates
is about 2, 130 ppm /.
3 - The quantity of lead contained in copper concentrates
smelted during 1970 is calculated to be 12, 780 tons.
6,000.000x^^.12.780
4 - Based on the assumption that 10 percent of the lead
. in the concentrates is lost in slags, solid wastes,
and products during processing, the atmospheric
emissions for 1970 (uncontrolled) are estimated at
113 500 tons.
12,780 - 0.1(12,780) - 11,500
5 - Based on an overall collection efficiency for lead
of 85 percent, the estimated emissions for 1970
(controlled) were 1, 700 tons.
1- Minerals Yearbook; Bureau of Mines; Copper 1970 Preprint.
2- Information obtained concerning EPA analyse^ of 48 samples
representing 5. 6 million tons of copper concentrates.
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-29-
PRIMARY ZINC
In the United States there are three types of processing
plants where primary zinc is recovered from ores, concen-
trates, fjime, flue dust, and residues. They are the horizontal-
retort and vertical-retort distillation facilities, and the electro-
lytic plants.
The major processing steps at the horizontal-retort facilities
include roasting, sintering, and distillation. The operations
are essentially the same at the vertical-retort plants, except
for the distillation step which is carried out in vertical units.
At the electrolytic plants the processing is, somewhat differ-
ent. It starts with roasting and is followed by leaching, puri-
fication, and electrolysis.
Zinc sulfide is the principal constituent of the raw materials
that are 'processed at the plants; however, lesser quantities
of lead sulfide and other minerals are present. Since lead
is in the raw material, lead emissions to the atmosphere may
be expected from all sources that emit dust and fumes. The
roasting, sintering, and distillation steps are probably the
sources of most plant emissions; however, unloading, stor-
ing, and conveying operations are responsible for substantial
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-30-
emissions.
In the literature there are numerous references to emissions
of metallic fume that occur in connection with roasting, sin-
tering, and distillation. It has been reported that gases re-
leased from sintering contain lead fume that is approximately
11 percent lead by weight /. Another reference indicates
that dust released from sintering is in the order of 250 pounds
per ton of zinc produced /. This information, coupled with
production figures from the U. S. Bureau of Mines, indicates
lead emissions due to sintering operations in 1970 were in the
order of 100 tons. Unfortunately,, there is not sufficient in-
formation available to accurately estimate lead emissions
from roasting, distillation, and fugitive sources.
As an alternative, the following estimate has been prepared.
1 - Approximately 1. 5 million tons ^f zinc ores and
concentrates were smelted in the United States
1- Johnson, G. A., Lund, R. E0 , and Peterson, K. F. ;
"Air Pollution Prevention at a Modern Zinc Smelter";
Air Repair; 3(3}.; Feb., 1954.
2- McKee, Arthur G. & Co.; "Systems Study for Control of
Emissions Primary Nor;ferrous SmeJting Industry"; for.
NAPCA; June, 1969.
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-31-
during 1970 _]_/.
2 - The average lead content of zinc concentrates is
about 6, 000 ppm /.
3 - The quantity of lead contained in zinc ores and con-
centrates smelted during 1970 is calculated to be
9, 000 tons.
i-5o°'oocx1.o6onoo-9-000
4 - The estimated lead content of the primary zinc
produced during 1970 is 3, 200 tons.
Production ' / Lead Lead
Grade
Special high
High
Inter mediate
Brass special
Prime western
Tons
370,000
100,000
48, 000
66, 000
294,000
Content /
0.003
0. 07
0.2
0.6
1. 6
Tons
11
70
96
396
4,704
5,277
1- Minerals Yearbook; Bureau of Mines; Zinc 1970 Preprint.
2- Information obtained concerning EPA analyses of 62 zinc
concentrate samples.
3- A. S. T. M. Specification B6-62T for primary slab zinc.
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-32-
Estimated lead content assumed to be 60 percent.of
the maximum allowable.
5,277 x 0. 6 3, 200
5 - Based on the a.ssumption that 10 percent of the lead
in the ores and concentrates is lost in slags and
solid wa.stes during processing, the atmospheric
emissions for 1-970 (uncontrolled) are estimated at
4, 900 tons.
9,000 - 0.1(9,000} 3,200 - 4,900
6 - Based on an overall collection efficiency for lead
of 95 percent, the estimated emissions for 1970
(controlled) were 240 tons.
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-33-
SECONDARY LEAD
In the United States secondary lead production is an important
factor in the total lead supply. During 1970 it was.nearly
equal to the production of primary lead. For the years 1966
through 1970 the U. S. Bureau of Mines reported the amount
of lead produced from scrap to be about 43 percent of the
quantity consumed. During that four-year period domestic
consumption increased only 2. 8 percent, while secondary
production increased 4. 3 percent.
The larger portion of the raw material supply for the second-
ary lead industry is "old scrap" reclaimed from discarded
end use products such as storage batteries, type metal, bab-
bitt, lead-covered cable5 and various items that contain sol-
der. During 1970 old storage ba.ttery lead plates accounted
I
for 65 percent of the total scrap consumed and the quantity of
"new scrap", consisting of drosses and residues, was nearly
16 percent.
•
The equipment and facilities for processing secondary lead
range from sweating furnaces and small remelting pots to
complex smelting and refining operations similar to those
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-34-
in the primary lead industry. The products produced are
antimonial lead, refined pig lead, solder, type metals, bab-
bitt, cable lead, and miscellaneous alloys. The most impor-
tant consumer of secondary lead is the storage battery industry.
The operations performed at secondary lead plants are many
and varied. At the larger facilities where reverberatory,
blast, and pot furnaces are employed, nearly any type of
scrap may be used and many different products can be pro-
duced. The grade of product, desired determines the type of
equipme'nt to be used and the scrap materials for the charge.
Hard lead, which typically contains from 5 to 12 percent anti-
mony, is made in the blast furnace. Semisoft lead is a pro-
duct of the reverberatory furnace and it normally contains
not more than 0. 3 to 0. 4 percent anumor-.y. Soft or high-
purity lead is the meta; obtained after semisoft lead has been
refined in the pot furna.ee.
The typical practice a.t larger plants is to trea.t the 'scrap
material in a reverberatorv furnace to produce a crude
semisoft lead and a leady slgg. The charges, which are
made up of a mixture of materials such as battery plates,,
drosses, residues, and lead scrap, are added intermittently
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-35-
to the furnace to maintain a small mound of unmelted material
on top of the bath. Then as the level of the molten metal
rises, the product is tapped off.
The reverberatory furnace is fired with gas or oil and the tem-
perature is maintained at approximately 2, 300 F. The smoke
and fumes produced include oxides, sulfides, and sulfates of
lead, tin, arsenic, copper, and antimony. It has been reported
that smoke and fumes are equal to approximately 7 percent of
the charge, slag about 46 percent, and metal recovery 47 per-
cent /. The same report shows the results of a reverbera-
tory test run conducted while processing battery groups at a
rate of 2, 500 pounds per hour. The dust and fume emission
at the furnace outlet was 130. 5 pounds per. hour, or 104 pounds
per ton of process weight. With an assumed metal recovery
of 47 percent, the dust and fume emission was.222 pounds per
i'
ton of product. Another report indicates that dust and fume
from a reverberatory furnace is approximately 225 pounds
per ton of metal reclaimed _/.
1- Danielson, J. A. ; "Air Pollution Engineering Manual";
PHS Publ. No. 999-AP-;40: 1967.
•
2- McKee, Arthur G. & Co. : "Systems Study for Control of
Emissions Primary Nonferrous Smelting Industry".; for
NAPCA; June, 1969.
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-36-
The leady slag from the reverberatory is further processed
in a blast furnace. It is part of the usual charge whichialso
includes miscellaneous drosses, oxides, scrap-cast iron,
coke, limestone, and rerun blast furnace slag. The coke is
the source*of heat and the combustion air that is required is
introduced through tuyeres located near the bottom of the furn-
ace. As the gases pass upward through the charge they carry
bits of coke fuel, oxides, and other particulates. Approxi-
mately 70 percent of the molten material is the product,
hard or antimonial lead, and 30 percent is slag.
The results of a blast furnace test run show 229 pounds per
hour dust and fume emission at the furnace outlet while pro-
cessing 2, 670. pounds per hour of battery groups, dross, and
slag _/. Based on the antimonial lead produced, the par-
ticulate emission was approximately 268 pounds per ton of
product.
After the production of semisoft and hard lead in reverbera-
tory and blast furnaces, further processing is often required
and pot furnaces may be used for this purpose. One of the
1- Daniels on, J. A.; "Air Pollution Engineering Manual";
PHS Publ. No. 999-AP-40; 1967.
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-37-
refining operations most commonly employed is removal of
copper and antimony to produce soft lead. Normally, the
semisoft lead from the reverberatory furnace is transferred
in a molten state to a pot furnace where the temperature is
allowed to drop to about 620 F. Sulfur is added, the mixture
is agitated, and copper sulfide is skimmed off as a dross.
When aluminum is added it reacts preferentially with copper,
antimony, and nickel to form compounds that can be skimmed
from the surface of the liquid. The antimony may also be re-
duced by bubbling air through the molten lead.
Pot furnaces are also used extensively for alloying operations.
When commencing with a metal that contains less alloying
elements than desired, the required amounts of each are cal-
culated and the proper quantities added to the melt. Operat-
ing temperatures are usually not more than 750 to 900 F and
emissions are relatively low. Uncontrolled emissions of
particulate have been reported to average 0. 8 pound per ton
processed /.
1- "Compilation of Air Pollutant Emission Factors (Revised)";
U. S. Environmental Protection Agency; Research Tri-
angle Park, N. C. ; Office of Air Programs; Publ. No.
AP-42; Feb., 1972.
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-38-
Lead recovery operations other than those describe'd also
add to the air pollution problem. Two of-the most common
are: (1) the sweating of lead and solder from scrap; and,
(2) the incineration of lead-covered cable. Emissions from
both these processes vary considerably due to the composi-
tion and condition of the scrap material.
While this study was in progress all of the large producers
of secondary lead and numerous local air pollution agencies
were contacted to obtain data regarding lead production, air
pollution control equipment, magnitude of emissions, and
other related information. Emission data was available
concerning. 29 plants that produced nearly 9.0 percent of the
secondary lead during 1970. The reports, which were prin-
cipally from industry, showed that lead emissions to the at-
mosphere averaged 0. 7 pound per ton of lead produced.
In addition to the information reported by industry, results
were available showing the lead content of particulate obtained
Curing five stack tests conducted during the period November,
1971 through February, 1972 _/. Two reverberatory and
1-Source Test Nos. 71-CI-29; 71-CI-33; 71-CI-34f
72-CI-7; and 72-CI-8.
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-39-
three blast furnace stacks were sampled. Lead emissions
from the reverberatories were 0. 03 and 0. 04 pound per ton
of lead processed, while those from the blast furnaces were
0. 006, 0.024, and.0. 08 pound per ton.
Industry reports of lead emissions from two plants were es-
sentially the same as the lead emissions calculated from
test results. At another plant, however, the lead emissions
were 0. 04 pound per ton according to test data, while the in-
dustry report was 0. 26 pound per ton. It wa.s subsequently
confirmed that this industry report included'all plant emis-
sions and not just the stack emissions from the reverbera-
tor y furnace.
Based on the information obtained from industry, lead emis-
sions to the atmosphere due to the production of secondary
lead totaled 220 tons during 1970. There were 13 secondary
plants where lead emissions were more than 20 pounds per
day.
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-40-
LEAD OXIDE
Lead has two simple oxides, litharge (PbO) and lead dioxide
(PbC>2), and a mixed oxide, red lead (Pb^O^J. Of these,
litharge and red lead are the most important. Litharge is a
high-tonnage, heavy chemical prepared by various processes
for a variety of specific uses including storage batteries and
pigments. The commercial product varies in color from
reddish-brown to grayish-black to bright yellow. Red lead
is prepared from lead monoxide and is added to paints for its
rust-inhibiting properties. It also finds some use in storage
battery plate pastes, b^t the partially oxidized black powder,
black oxide, or battery oxide, is most widely used for this
purpose. Usually the black oxide used in storage batteries
is a mixture of about 60 to 80 perrerit. lead monoxide, the
remainder being fin> ly divided, metallic lead. It is quite dis-
tinct from the usual litha.rge avai.la.ble on the market.
Lead dioxide is ar. oxidizing agent, in the manufacture of dyes,
chemicals, matches, pyrotechnics, and rubber substitutes.
It is also used as a curing agent for liquid polysulfide poly-
mers, converting them to rubbers a.t room temperature
without shrinkage.
-------
-41-
The commercial manufacture of lead monoxide is based on
furnace techniques. There are four principal.methods in use:
(1) metallic lead is partially oxidized and milled to a powder
which is charged into a reverberatory furnace at about 1, 100 F
to complete the oxidation to ordinary "chemical" litharge;
(2) pig lead is oxidized and stirred in a reverberatory furn-
ace or rotary kiln directly to lead monoxide; (3) molten lead
is run into a cupelling furnace held at about 1, 800 F and
molten litharge is produced; and, (4) molten lead at about
950 F is atomized into a flame where it burns vigorously,
producing "sublimed" or "fumed" litha.rge. In all cases, the
product must be cooled quickly to below 570 F to avoid forma-
tion of red lead.
The litharge used in battery pa.stes is usually a mixture of
lead oxide and a finely divided metallic 1-ead, variously known
as gray oxide or black o.xide depending on the amount of lead
it contains. The litharge-lead mixture is manufactured by
the ball mill process or the Barton process. Using the ball
mill, the pieces or balls of pure lead are oxidized by the
frictional heat generated from the tumbling of the lead in the
mill. This oxidation reaction is exothermic and the heat
generated acc.elera.tes it further. During the action the lead
-------
-42-
oxide that forms on the surface of the lead balls is removed
and ground. This mixture usually approximates 70 percent
lead oxide to 30 percent unoxidized finely divided lead. Ball
mill oxides give batteries long life and good capacity, but
they are being superseded by Barton oxides. The Barton pro-
cess depends on the oxidation of lead in the molten state.
Molten lead is fed into a circular pot and rapidly stirred. A
series of baffles within the pot atomize the lead, breaking it
into extremely small droplets. An air stream in the pot oxi-
dizes these small droplets, and the material is carried by the
air stream to a collecting system.
Commercial red lead is composed principally of trilead
tetroxide, Pb-O^, and smaller amounts of lead monoxide.
The manufacture of red lead begins with litharge which is
charged into a reverberatory furnace, where it is held at a
temperature of 900 to 950 F while air passes over. The
process consists of oxidation until the desired level of red
lead is obtained. An 85 percent grade red lead is usually
completed in about 24 hours but a longer time is required
for grades containing a higher percentage of true red lead.
Following cooling, the material is ground to required par-
ticle size.
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-43-
Lead dioxide is a brown powder which decomposes rather
easily to lower oxides, releasing oxygen when heated to
555 F. It is commercially produced, by the treatment of an
alkaline red lead slurry with chlorine, but may also be pro-
duced by anodic oxidation of solutions of lead salts. In this
case a strong oxidizing agent such as hydrogen peroxide or
chlorine gas is added to the solution to obtain the lead dioxide.
Production reports for 1970 reveal that nearly 78 percent of
the 400, 707 tons of lead oxide produced in the United States
was used in storage batteries /. Another 19 percent was
used in the form of red lead and litharge in the manufacture
of pigments. Most of the oxide was processed at battery
plants or at the secondary lead plants.
Information obtained from companies that currently produce
about 60 percent of the lead oxide indicates that lead emis-
sions from baghouses range from 0.2 to 21. 8 pounds per ton
processed /. During 1970 the lead emissions from lead
oxide plants averaged 0. 7 pound per ton of lead processed.
1- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
2- Private communication.
-------
-44-
Lead emissions to the atmosphere due to the manufacture of
lead oxide totaled 140 tons during 1970. There were 16 plants
producing lead oxide where lead emissions were more than 20
pounds per day.
-------
-45-
CONSUMER PRODUCT MANUFACTURING
In the United States during 1970 nearly 70 percent of the
primary and secondary lead was used in metal products, in-
cluding storage batteries, ammunition, solder, cable cover-
ing, type metal, brass and bronze, bearing metals, caulking
lead, sheet lead, pipe and fittings, collapsible tubes, foil,
casting metals, and terne metal. Approximately 20 percent
was used in gasoline antiknock additives and miscellaneous
chemicals. The remainder was used in pigments and for
other miscellaneous purposes.
The largest quantity of lead was consumed in the manufacture
of storage batteries, principally for motor vehicles.
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-46-
STORAGE BATTERIES
The largest single use of lead in the United States is in the
manufacture of lead-acid storage batteries, which are the
type of batteries found in automobiles, motor trucks, mine
locomotives, golf carts, industrial trucks, emergency light-
ing systems, telephone networks, and numerous other appli-
cations. During 1970, nearly 44 percent of the total lead
supply was used for this purpose. From the standpoint of
lead emissions to the atmosphere, the battery manufacturing
industry is important because many factories are.located in
densely populated areas. There is a large emission potential
from each, even from the relatively small plants.
The installations in which storage batteries are manufactured
vary considerably in size and in the type of operations per-
formed. Some of the larger plants make their own lead oxide
and some operate secondary lead recovery facilities. Some
plants produce less tha.n 50 batteries per day, while others
produce more than 12, 000 per day. The quantity of lead and
lead oxide used each day may be less than 500 pounds or
more than 300, 000 pounds. At a large plant, without air
pollution controls, the lead emissions to the atmosphere
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-47-
could be several tons per day.
A lead-acid storage battery consists of positive and negative
plates, separators, an electrolyte of dilute sulfuric acid,
and a case. Both, wet- and dry-charged batteries are pro-
duced and the general oper-ations in the manufacturing process
are shown in Figure IV. The plates are made iip of a struct-
ural member called the grid and lead oxide paste. The grid,
which is inactive, provides mechanical support for the active
portion and a conductive path for the electric current. These
perforated grids are generally cast from lead hardened by the
addition of between 6 and 12 percent antimony, including small
amounts of arsenic and tin. Hard lead is the term applied to
the most common alloys used in storage battery construction.
A typical analysis of hard lead is as follows: antimony, 7
percent; tin, 0.25 percent? arsenic, 0. 1 percent; and lead,
92. 65 percent.
Casting techniques for grids vary with the alloy used, the
type of molds, and the mold preparation before casting.
Highly efficient casting machines have been developed for
gravity-casting of grids. A molten lead alloy is poured into
iron grid molds at a.bout 900 F where it is allowed to freeze.
-------
-48-
STORAGE BATTERY MANUFACTURE
FLOW DIAGRAM
Oxide
A,wi*w« *" MIXER 1 |
PAS
PLATE
Separators _
• ^ STAJ
BUB
Dry Battery Line
t
FORM
*
DRAIN & RINSE
f
DRY
V
BURN POST
j .
iiii:isi •- SEAL
W£
PAI
; AS TING
TING Si1— — *-
^
CURING
JK11MG ' — " w
*
^NING Fume_ ^
Wet Battery Line
i p
AFPTCMBLY ^r Ua,s,^ an4.,
, ^ Cover
t
BURN POST
t
ACID FILL j
^
FORM
*
CHANGE ACID
1 *
JBOOST CHARGE
r
L.SH |
u
NT |
Shipping M..
Figure .IV
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-49-
When the grids are ejected from the molds they can be hard-
ened by quenching or spraying with cold water prior to trim-
ming and stacking.
Typically, the lead oxide paste is made by adding water to
lead oxide in a mixer and blending to form a stiff paste. Di-
lute sulfuric acid is then added slowly with constant mixing
and cooling until the desired consistency and density are at-
tained. Three types of mixers are used; they are known as
the muller type, the dough type, and the day type. The muller-
type mixers are most common especially for batch sizes from
I, 200 to 2,400 pounds. Mixers should be water-jacketed and
air-cooled to prevent excessive temperatures which cause
the paste to become stiff and difficult to apply to the grids.
Pastes for both positive and negative plates are made simi-
larly except that so-called "expanders" are added to negative
pastes to serve as an aid in activating these plates at low
temperatures and high rates of discharge.
Following the preparation of the paste, machines are used
to force it into the interstices of the grid structure. Then
there is a short drying period and a curing step prior to the
stacking and burning operations. Curing is a process tha •
-------
-50-
increases the strength of the plates. Stacking is the proced-
ure of assembling the cured plates and their separators into
elements. Burning is the term applied to the operation of
melting lead to weld the plates together. The negative plates
are joined by burning to form one electrode, and the positive
plates are joined together likewise to form the other. The
welded elements can go either to the dry battery line or the
wet battery line.
In the dry battery line, the element stacks are placed in con-
tainers filled with acid and connections are made for the form-
ing process, which is a charging operation that converts-the
paste to sponge lead in the negative plate and to lead peroxide
in the positive plate. During this process, which requires
severs,! hoursa the sulfuric acid becomes slightly more con-
centrated. After the element has been formed it is removed
from the container, permitted to drain for a very short period,
rinsed by moving counte r cur r ent through fresh wa.ter, and
placed in an oven to dry. The dried elements are assembled
in a battery case, the posts are welded' in place, and the
cover sealed to the case. The completed battery is then
ready for washing, painting, and shipping.
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-51-
The welded assembled elements can also be used to produce
the wet battery. In this instance the elements are placed in
a battery case, the posts burned, and the battery filled with
acid. These batteries undergo the same forming process as
the dry batteries, after which the acid is dumped. Fresh
acid is then added and the battery is given a boost charge
prior to washing, painting, and shipping.
The above is a brief description of the principal operations
involved in lead-acid storage battery manufacture. There
axe, however, many minor process variations in all of the
plants that were visited during this study.
Nearly all steps in storage battery manufacturing employ
the u.se of lead and have a potential for lead emissions; how-
ever, only the principal emission sources are indicated in
Figure IV. During melting and casting operations, the tem-
perature of the molten lead is usually below 900 F and the
degree of fuming is not significant. In many plants hoods
have been installed over the melting pots for protection of
personnel, and the fumes .are discharged directly to the at-
mosphere without passing through dust collecting devices.
In this, report the manufacture of lead oxide has been discussed
-------
-52-
separately. Even though ma..ny large battery manufacturers
prepare this material in their own plants, it must be handled
in much the same manner as purchased oxide. Usually it
must be moved, stored, and moved again before it enters
the weigh bins and paste mixers. Each time it is handled a
considerable amount of dusting occurs and care is required
to avoid the release of dust to the atmosphere. Normally,
the storage and handling systems are enclosed and connected
to weigh bins and paste mixers through dust-tight seals.
Bag filters and cyclone collectors are commonly employed
to remove dust from the air that is discharged from the
equipment.
After the damp lead oxide paste has been prepared, the emis-
sions are relatively insignificant until the pasted plates have
been dried. Then there is more dusting as the plates are
handled and stacked. D^'mg burring on welding of the as-
sembled elements, fuming is th<= problem. It is common
practice for the operators to wear protective masks at stack-
ing and burning stations. It is also common practice to in-
stall hoods and exhaust dust systems for removal of pollu-
tants from these areas.
-------
-53-
According to the information obtained during this study,
more bag filters are'employed for air pollution control, in
battery plants than any other type of dust collecting equip-
ment. Cyclone collectors with water sprays are also popu-
lar and are sometimes used in series with bag filters. The
data received from 5.5 plants, employing about 11, 000 per-
sons and producing approximately 75 percent of the storage
batteries, indicates that lead emissions to the atmosphere
due to battery manufacture totaled 480 tons during 1970.
Lead emissions from plants with air pollution controls aver-
aged 1. 3 pounds per ton of lead processed, while those from
plants without controls were about 8 pounds per ton. It is
estimated that there are 24 battery plants where lead emis-
sions to the atmosphere exceed 20 pounds per day.
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GASOLINE ADDITIVES
In the United States the second largest use of lead is in the
manufacture of the lead alkyls, tetraethyl lead (TEL) and
tetramethyl lead (TML), which constitute practically all of
the gasoline antiknock agents in use today. During 1970 ap-
proximately 20 percent of the total lead supply was used for
this purpose.
From the standpoint of lead emissions to the atmosphere,
the manufacture of TEL and TML is important. Their vola-
tility is relatively high and emissions are difficult to control
because they occur primarily in vapor form.
Although some lead alkyls are manufactured by an electro-
lytic method, 90 percent or more are produced in a sodium-
lead alloy process in either batch or continuous reactors. . In
the batch process tetraethyl lead is made by the reaction of
ethyl chloride with a sodium-lead alloy, according to the
equation 4 NaPb + 4 C2H5C1 —> J^bfC^H^ 4- 3 Pb +
4 NaCl.
Following the completion of the reaction, the product is
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-55-
chloride. Then ethylene dichloride, ethylene dibromide, and
dyes are combined with the product to form the finished additive.
The first step in tetraethyl lead production (see Figure V) is
the making of the sodium-lead alloy. Lead, which may be
virgin and recycle, is melted and mixed with sodium in a
melt pot in a ratio of 90 parts lead to 10 parts sodium. This
produces a lead-sodium alloy which is flaked, then loaded
into hoppers under a blanket of nitrogen to be taken and
dumped into horizontal autoclaves.
After the alloy is in the autoclaves, the ethyl chloride is fed
over a period of several hours. The reaction takes place
during the ethyl chloride feed time and an additional 30 to 60
minute cook period. The tempera.ture in the autoclave is
maintained at about 160 to 165 F and by-product gases are
vented throughout the reaction. Finally, the autoclaves are
rented of excess ethyl chloride and the reaction mass is dis-
charged into steam stills containing water.
In the still operation, the remaining dissolved ethyl chloride
is removed with steam followed by steam distillation of the
TEL from the residual mixture of lead metal and sodium
chloride. Steam is passed through the still for about two
-------
-55-
TEL 'BATCH PLANT FLOW DIAGRAM
SODIUM-LEAD ALLOY PROCESS
Ethyl Chloride
Lead
i
LEAD
MELTER
Sodium
ALLOY
POT
AUTOCLAVE
STEAM
DISTILLATION
LEAD
RECOVERY
FURNACE
SLUDGE
PIT
TEL
PURIFI-
CATION
BLENDING
ETHYL
CHLORIDE
PURIFI-
CATION
ETHYL
CHLORIDE
RECOVERY
Ethvlene
Dibromlde
Ethyl «ne
Dichloride
Dve
Antioxidant
Shipping
Figure V
-------
-57-
hour s while the mass is agitated.
Following steam distillation, the crude TEL is purified by
air blowing or washing with dilute aqueous solutions of oxi-
dizing agents such as hydrogen peroxide in order to remove
small amounts of organometallic compounds of other metals.
Then the tetraethyl lead is washed with water and separated,
and is ready for blending into antiknock fluids.
Residue from the steam-still distillation is dropped into a
sludge pit. Sodium chloride is washed from the residue and
the remaining lead metal sludge is dried, purified by smelt-
ing, and recycled into the sodium-lead alloy manufacture.
This is a. very important step as less than 25 percent of the
lead in the alloy is converted to tetraethyl lead on one pass;
thus, a large amount of metallic lead remains in the residue.
For every pound of lead in tetraethyl lead, four and one-half
times that amount must be handled in the process-.
The antiknock fluid is completed .by mixing the following in a
blender: tetraethyl lead, halogen compound, an identifying
dye, antioxidant, and a surface ignition control compound.
Finally it is pumped through bag filters into tank cars or
bulk-storage tanks -ready for shipment.
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The continuous process for the manufacture of TEL is an
adaptation of the batch process. The principal steps are es-
sentially the same, except a continuous reactor is used in-
stead of autoclaves and product separation operations vary
somewhat.
Tetramethyl lead is manufactured by a batch process similar
to that described for TEL. The essential difference is that
methyl chloride is used instead of ethyl chloride, aluminum
chloride is used as a catalyst, and higher operating temper-
atures and pressures are required for the TML synthesis.
The electrolytic process for making TEL and TML is based
on the fact that organomagnesium halides ionize in ether sol-
vents and these solutions can be electrolyzed. It is claimed
the process has two advantages over other methods. First,
the electrolytic process is more versatile and various alkyl
lead compounds can be produced without major modification
to the equipment. Second, inefficient recycling of metallic
lead is avoided since this by-product is not formed in the
reaction.
The first step in the electrolytic process (see Figure VI) is
the batch preparation of the alkylmagn.esium halide. The
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TEL-TML PLANT FLOW DIAGRAM
ELECTROLYTIC PROCESS
Magnesium
1
MAGNESIUM
CHIPPER
GRIGNARD
REACTOR
Lead
1
Recycle Ether
Solvent
Alkvl
t
Halide
ETHER
PURIFI-
CATION
Recycle
Alkyl
Halide
ELECTROLYSIS
CELLS
STRIPPER
ALKYL
LEAD
RECOVERY
Magnesium.
Alkyl
Lead
1
Alkvl Lead
Ether
Magnesium
Chloride
BLENDED
Chloride
Ethyl
! Dibromide
; Ethvlere
Dichloride
Toluene
Dye
AT ri ox i da.-:
Shipping
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-60-
reactants are magnesium chips and alkyl halide. The solvent
is a- mixture of ethers. The reactants plus the solvent are
fed into Grignard reactors. The reaction is exothermic and
is carried out at low pressure (10 to 20 p. s. i. g. ) and a tem-
perature of about 100 F. The resulting alkylmagnesium hal-
ide and ether solvent is metered into the electrolysis cells
where lead pellets .are used as the anode and steel walls as
the cathode. After electrolysis, the solution contains alkyl
lead, ether solvent, alkyl halide, and magnesium chloride.
First, the alkyl halide is stripped from the solution, then
the other three compounds are separated by distillation and
solvent extraction. The resulting alkyl lead is fed into a
blender where other ingredients are added to produce the
final product.
While this study wa.s in progress, information was obtained
from industry regarding the magnitude and nature of lead
emissions, manufacturing operations, and air pollution con-
trol equipment. Part of the lead emissions are in vapor
form and part are particulates composed of lead carbonate,
lead chloride, and lead oxide. The vapors, when emitted,
are TEL. and TML., but they are soon converted to lead ox-
ide after exposure to the atmosphere. One lead alkyl
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manufacturer has reported that electron micrographs indi-
cate particulates range in size from 0. 01 to 2 microns, but
are generally below 0. 5 micron.
High-energy venturi scrubbers and cyclones with water sprays
are the types of equipment most often used to control particu-
late emissions. Refrigeration systems are used to lower the
temperatures and reduce vapor emissions.
The information obtained from industry indicates that lead
emissions to the atmosphere due to the manufacture of lead
alkyls totaled 1, 900 tons during 1970. Lead emissions
ranged from 0. 8 to 29 pounds per ton of lead used, averag-
ing 13.6 pounds per ton, and they exceeded 20 pounds per
day at each of the six manufacturing plants.
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PIGMENTS
The use of lead in pigments and paints is still important
even though the quantity used for this purpose has decreased
substantially during recent years. Basic carbonate white
lead, basic lead sulfate, leaded zinc oxide,, and certain lead
silicates are employed in some outside paints. Red lead or
"blue" basic lead sulfate may be an addition in primers and
metal protective paints. Lead also produces certain colored
pigments, notably the lead chromates. Most of the yellows,
greens, and reds are lead chromates, either alon'e or pre-
cipitated with other pigments. Leaded pigments may be used
as artists' colors or in printing inks, and yellow shades are
rapidly growing as traffic, ma. r-king pair.ts.
Basic carbonate white lead is one of the oldest, pigments
used in paints. Because of its basic qualities, white lead
undergoes a reaction with linseed oil fatty acids which makes
it useful in conjunction with otie.r lead pigments, zinc oxide,,,
titanium dioxide, and extenders for the manufacture of ready-
mixed oil paints. The lead reaction imparts adhesion, tough-
ness, elasticity, and improves durability. Films pig.ment.ed
with ba.sic carbonate white lead wedther in such a manner
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that the paint film, is maintained in good condition for repaint-
ing without extensive preparation.
There are several processes for manufacturing basic carbo-
nate white lead. They all make use of the reaction of lead or
litharge (PbO) with acetic acid to produce lead acetate, which
is then reacted with carbon dioxide to form basic carbonate
white lead.
Basic sulfate white lead imparts to oil paint films the prop-
erties of adhesion, elasticity, toughness, and durability.
However, it is not satisfactory as the sole pigment in pure
white lead paint and is used in conjunction with other pigments
I
in exterior oil paints. It may be prepared by chemical or
fume processes. The chemical process begins with finely
divided lead or a mixture of lead and litharge suspended in
water. Sulfuric acid is then added to produce a precipitate
of basic sulfate white lead which is filtered off, dried, ground,
«
and bagged. The fume processes use baghouse collection. In
one method lead sulfate, or galena, is heated in an oxidizing
atmosphere, but another procedure uses a spray of molten
lead which is reacted with sulfur dioxide obtained by burning
sulfur. Both processes produce a fume of basic sulfate
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-64-
white lead which is converted to a fine powder by cooling
and then collected.
Basic silicate white lead with characteristics similar to
basic carbonate white lead is a pigment useful in paints used
to cover redwood or cedar siding as it inhibits discoloration
caused by the natural dyes in these woods. This pigment is
prepared by a dry-phase reaction in which proper propor-
tions of silica, lead oxide, and basic lead sulfate are heated
together.
Leaded zinc oxides may also be used as a pigment in exter-
ior finish coat oil-base house paints as it is a convenient
means of introducing both lead and zinc into the formula.
These oxides contain basic sulfate white lead. They may be
produced either by smelting and cofuming combinations of
zinc and lead sulf-de ores, or by mechanically blending frac-
tions of zinc oxide and basic lead sulfate which have been
prepared separately.
An important family of yellow and orange inorganic pigments
results from the characteristic medium yellow color of nor-
mal lead chromate. A wide range of closely related yellow
and orange pigments is produced, from light greenish-yellow
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shades to extra deep orange shades. The chromes in general
combine brilliance of color and great staining power with con-
siderable hiding power. They are reasonably stable and re-
tain their color even in impure air, although they are not ab-
solutely fast to light, gradually fading on exposure. Another
desirable property is their ability to inhibit the corrosion of
metals. Thus.they are efficient as primers.
All chrome yellows are precipitates which are formed in
tanks equipped with agitators. The precipitates are washed
to remove soluble compounds, filtered, dried at tempera-
tures not above 200 F, and ground. Raw materials for the
production of chrome yellows are numerous and varied.
They include litharge or lead carbonate, sodium bichromate,
acids such as nitric, acetic, sulfuric, or hydrochloric, and
various alkalies. If litharge, nitric acid, and sodium bi-
chromate are used the litharge ;a.nd nitric acid combine to
form lead nitrate and water. When sodium bichromate is
added, thn result is lead chromate, sodium nitrate, and
nitric acid. This produces a medium yellow.
The primrose and lemon shades of chrome yellow differ
from the medium yellows in composition in that substantial
-------
-66-
amounts of lead sulfate or other lead compounds are present
i
with, the normal lead chromate. The process of manufacture
is generally the same as that for the medium yellows, ex-
cept that a part of the sodium bichromate is replaced by sul-
furic acid. Many variations in shade may be obtained by con-
trolling the exact percentage combination of lead chromate
and lead sulfate.
The chrome yellows and oranges have relative low cost and
good qualities which make them useful pigments in paints,
lacquers, traffic-line paints, printing inks, papers, linol-
eum, and leather finishes.
All chrome oranges contain basic lead chromate, which is
present in increasing proportion to the normal lead chrom-
ate to obtain the desired color. The more completely the
orange chrome is converted to the basic compounds, the
deeper the shade of reddish-orange produced. Manufactur-
ing equipment and processes are generally similar to those
used for making chrome yellow. The chrome oranges are
more resistant to alkalies and less resistant to acids than
the yellows. Their larger crystals give them improved light-
fastness but lower hiding power. One specific bright
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-67-
red-orange shade of basic lead chromate is used for airport
markings.
Related to the basic lead chromates is basic lead silico-
chromate. Basic lead chromate is deposited on the surface
of a core of silica. During manufacture the lead chromate-
silica composite is subjected to calcination conditions to
bond the chromate coating to the silica, converting part of
the basic lead to basic lead silicate. This pigment is widely
used in.priro.ers for ferrous metals. When exposed to weather
it does not undergo carbonation as does the pigment red lead.
Metal primed using basic lead silicochromate may be stored
in the field for extended periods without rapid weather deter-
ioration. The pigment may also be used in intermediate and
finish coats of paint for steel structures to provide additional
protection against corrosion.
Chrome greens are some of the most widely used pigments.
They find wide application in many kinds of paints such as
house paints, sash and trim paints, enamels (both air-drying
and baking), lacquers, and flatrpaints; they are also used in
printing inks, calcimines, oilcloth, and paper. The pig-
ments include a wide variety of hues from extra-light vellow
-------
-68-
green to an extra-dark green. These greens are all intimate
mixtures of chrome yellows and iron blues. Since these pig-
ments are composites, their compositions depend on the pro-
portions of chrome yellow and iron blue. Variations in hue
may also be produced by the shade that is used, which is a
redder yellow producing a more olive green.
The mixtures that produce chrome greens may be made by
blending fresh wet precipitates, by blending the dry powders,
or by causing the chrome yellow precipitate to form on al-
ready prepared and washed iron blue. Manufacture requires
the same equipment as needed for the chrome yellows: tanks
for solution, precipitation, and washing; filters; driers;
and pulverizers.
Another group of oranges using lead are the molybdenum
oranges which are more brillant than the chrome oranges.
These oranges are characterized by strong color, high hid-
ing power, and high tinting strength. They are used in many
kinds of paints, enamels, and lacquers. Use is also made
in floor coverings and printing inks. These pigment colors
result from, the coprecipitation of lead chromate and lead
molybdate, often in the presence of lead sulfate. Lead
-------
-69-
molybdate is a white compound; the coprecipitation of lead
chromate and lead sulfate produces a light chrome yellow.
Molybdenum oranges are produced in a wide range of com-
position, but a typical grade consists of 81 percent lead chro-
mate and 11 percent lead molybdate.
Blue basic lead sulfate is another lead pigment sulfate known
as blue lead and sublimed blue lead. It is a dark slate-gray
color pigment used chiefly in primers and finish coat paints
for structural metal. Blue lead is manufactured by feeding
a mixture of lead ore and coal or coke into a Scotch-hearth
furnace. The lead sulfide in the ore is partially oxidized to
lead sulfate and lead oxide, which combine to form a fume
;
of basic lead sulfate. Excess lead sulfide and carbon, lead
sulfite, and zinc oxide also comprise a part of the fumes
which are collected in baghouses.
Litharge and red lead are both oxides of lead. These oxides
are important pigments and their preparation has already
been discussed. Litharge was used almost exclusively until
modern times. Red lead is now an alternative to litharge.
Both oxides are used mainly in the preparation of boiled oil,
varnishes, and liquid driers. Their activity as driers is
-------
-70-
developed by heating with oil. When they combine with the
oil, soluble lead soaps are formed. In addition, red lead is
used as a pigment for paints to protect metal surfaces. It
is a prime coat on massively exposed iron and steel struct-
ures such as bridges, ship hulls, water tanks, and fuel tanks.
In combination with linseed oil, it forms tough elastic films
with excellent adhesion to ferrous metals. Litharge is the
usual starting point for the manufacture of other lead chem-
icals such as chrome pigments, basic lead carbonate, basic
lead sulfate, basic lead silicate, lead arsenate, red lead,
and lead soaps and greases.
Other pigments using lead include antimony yellow and cas-
sel yellow which are used as artists' colors. Orange mineral
is another color resulting from further oxidation of red lead.
Calcium plumba.te, a light yellowish-buff pigment, is made
by heating lime and litharge at about 1, 300 F. Flake pow-
dered lead is sold as a powder or a paste for use as a pigment
in primers on galvanized iron, stainless steel, lead, and
light metals.
Paint manufacturing ir.. the United States is an industry com-
prised of a few large companies and numerous small ones.
-------
-71
Currently there are more than 2, 000 establishments that
manufacture paint and about 150 that make pigments. The
information obtained from industry for this report indicates
that most pigment manufacturers use some type of air pollu-
tion control equipment, but that many of those mixing paint
only have none. One large pigment company without controls
has reported analyses which show that lead emissions aver-
age about 9. 5 pounds per ton of lead contained in the product.
Others using bag filters and scrubbers reported that lead
emissions average 1. 3 pounds per ton of lead used. Based
on an average of 1. 3 pounds per ton, lead emissions result-
ing from the manufacture of pigments are estimated by the
Contractor at 63 tons for the year 1970. There are 6 pig-
ment plants with lead emissions exceeding ZO pounds per day.
Reports from several large paiiit manufacturing establish-
ments indicate that wet scrubbers and bag filters are the air
pollution controls most often used in connection with paint
mixing operations. Sometimes both types of equipment are
used in the same plants. Lead emissions when using these
controls have been reported to range from less than 1 to
nearly 5 pounds per ton of lea.d processed, averaging 1. 3
pounds per ton. When not controlled, emissions range from
-------
-72-
less than 3 to more than 20 pounds per ton. Based on an
average of 3 pounds per. ton, lead emissions due to paint
mixing during 1970 have been estimated by the Contractor
at 147 tons.
-------
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AMMUNITION
Lead's density has made it an ideal metal for bullets and
shot, as it permits the attainment of a high momentum nec-
essary for maximum striking power. Most of the lead shot
manufactured goes into shells for sporting ammunition while
the usual military applications are bullets and bullet cores
for pistol, rifle, and machine gun.
The lead used in shot production is usually alloyed with ar-
senic and1/or..antimony. Additions of up to 1 percent arsenic
increase fluidity and allow the formation of a perfect spher-
ical shape. From 2 to 6 percent antimony in the alloy in-
creases hardness for long-range loads.
The manufacture of shot is an example of casting without a
mold. Casting takes place from the top of a tower or the
upper part of a mining shaft. The height of the pouring floor
is determined by the ma.ximum size of the shot to be poured;
the larger the shot to be made, the higher the pouring floor.
The lead alloy in pasty form is put into a gas-heated iron
pot, the base of which is perforated with a series of holes
smaller than the shot desired. The bottom of the pan is
covered with a sludge of oxidized lead so that the molten
-------
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metal will ooze slowly through and form rovind drops. Dur-
ing the stirring of the pasty metal, spheres of molten alloy
flow through the sieve, brea.k into individual drops, and fall
to the lower end of the shaft where they are caught in a tank
of water. During the fall the metal cools and solidifies into
spherical shot. The water keeps the spheres from being
flattened during landing.
After the shot is collected in the water it is dried, mixed
with graphite to polish it, and then screened to eliminate
odd sizes. Next, the shot is rolled down sloping glass tables
which have a narrow trough at the bottom edge. Perfectly
round shot gather enough momentum during rolling to leap
the trough, but misshapen shot fall into the trough for sub-
sequent remelting. Grading operations are repeated sev-
eral times. Then the shot is loaded into shells and becomes
ready for use.
For bullet cores, lead is usually extruded as wire, which is
cut to length and swaged to the approximate shape of the bul =
let. The size and shape of the cores vary depending upon the
type of bullet. In "ball" cartridges the entire core is lead
alloy, but in tracer or incendiary cartridges, the lead core
-------
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is somewhat shorter than the jacket, the remaining space
being filled with the tracer or incendiary chemicals.
Lead azide is an initial detonating agent used in commer-
cial blasting caps and military ammunition. It is prefer-
able to mercury fulminate with respect to stability, cost,
and availability of raw materials. Lead azide is practically
insoluble in most common solvents., is less sensitive to heat,
impact, and friction than mercury fulminate, and overcomes
a lower rate of detonation to be a superior initiator of deto-
nation.
The compound may be produced in crystalline, colloidal, or
dextrinated forms. The preparation of each form calls for
a chemical reaction of sodium azide with, lead nitrate or lead
acetate in solution. Precipitated lead azide is then washed
i
and stored under water. Any by-product liquor can be treated
with, soda ash to precipitate lead as lead carbonate.
The data presented in this study was obtained from estab-
lishments that consume about 35 percent of the lead used in
the manufacture of ammunition. These companies have re-
ported that their operations include lead casting, shot, drop-
ping, extrusion, slug forming, and tumble polishings as well
-------
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as the manufacture of priming mixtures. Air pollution control
equipment consists of bag filters for tumble polishing opera-
tions only. According to recent stack tests conducted by one
ammunition manufacturer, lead emissions to the atmosphere
are less than one pound per thousand tons of lead processed.
Based on the data reported, lead emissions due to the manu-
facture of ammunition are considered to be negligible.
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SOLDER
Due to the wide variety of soldering procedures in use today,
there is a great demand for solder in various forms. Solder
can be obtained as wire or tape in a continuous length on a
spool or shaped and cut into "preforms" such as rings, wash-
ers, discs, or pellets. It may also be purchased as bars,
wire, or pellets for filling and maintaining solder in baths
and pots.
Dip soldering may be very useful and economical inasmuch
as an entire unit, comprising any number of joints, can be
soldered merely by dipping the part in a bath of molten sol-
der. The soldering of printed circuit boards is an excellent
example. Most commonly a printed circuit is a sheet of in-
sulating material carrying a pattern in copper foil. The
pattern is the electrical connection between circuit compon-
ents soldered to the board. These components can all be
soldered simultaneously by dipping for 4 to 8 seconds. The
temperature of the dipping bath should be between 475 and
525 F. Solder pots or solder baths permit work pieces to
be dipped by hand or to be done mechanically.
A good example of mechanical operations is the soldering of
-------
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cans. Side seams of cans are soldered on a machine con-
sisting of a solder-coated roll operating in a bath of molten
solder. The roll revolves bringing molten solder up to the
seam of the can, which moves rapidly along a roll parallel
to the axis of the solder roll. A buffing wheel then removes
excess solder from the cans.
Flame soldering is mostly a manual operation employing a
torch and is widely used in plumbing, automotive body work,
and for structural joints. However, flame heating is not re-
stricted to manual operations. There are numerous auto-
matic applications where the work is passed through a sta-
tionary flame.
Oven heating is another well-established industrial tool for
soldering. A smooth conveyor arrangement passing through
furnace ovens seems preferable. Since there is no practi-
cal way to add flux and/or solder during the trip through the
furnace, the parts are stacked and fluxed with a preform of
soldering alloy in place. As the parts pass into the furnace.
the entire assembly is heated to soldering temperature. Fol-
lowing this, the parts remain on the conveyor traveling for
a sufficient length of time to reach the solidus temperature
-------
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of the particular solder alloy employed. This cooling period
is important since there must be no movement between the
members in order to achieve a quality joint.
There are numerous procedures used in industrial soldering,
but regardless of the application the temperature of the sol-
der is relatively low and lead emissions due to melting are
not a serious air pollution problem. There are, however,
other operations associated with the melting that may result
in substantial emissions if not properly controlled. An ex-
ample is the automatic side seam soldering of cans as re-
ported by one establishment. After the soldering, the excess
is wiped from the joint by a rotating cloth buffer which creates
some dust. Hoods, exhaust ducts, and cyclone collectors are
used, but there is some dust that escapes the system. Parti-
I
cles entering the system are in flake form, mostly about one-
half inch diameter.
Particles exhausted to the atmosphere are in the order of 20
microns or smaller. When using solder averaging 40 per-
cent lead, the emissions to the atmosphere as reported are
I..? pounds of lead per ton of solder consumed. One large
can manufacturing plant currently uses solder at the .rate of
-------
-80-
3, 300 tons per year, and lead emissions are reported at an-
average of 15 pounds per day.
It has been reported that the lead in the solder consumed in
the United States during 1970 was 69,707 tons /; however,
there is a lack of information concerning the quantity used
for can manufacture and various other purposes. Conse-
quently, the estimates of lead emissions resulting from the
manufacture and use of solder may vary considerably. For
this report it has been assumed that lead emissions average
3 pounds per ton of lead contained in the solder and that
emissions in the United States during 1970 totaled 110 tons.
The rationale for the above assumption is that emissions
are more than 1. 6 and less than 4. 25 pounds per ton of lead
contained in the solder. It has been reported that uncontrolled
particulate emissions from pot furnaces at secondary lead
smelters average 0. 8 pound per ton processed /. In that
case there is one melting operation, but when solder is
1- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
2- "Compilation of Air Pollutant Emission Factors (Revised)";
U. S. Environmental Protection Agency; Research Tri-
angle Park, N. C. ; Office of Air Programs; Publ. No.
AP-42; Feb., 1972.
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-81-
manufactured and used the metal is melted twice. The 4. 25
pounds per ton of lead is based! on the can manufacturing data.
The 1. 7 pounds per ton of solder is equivalent to 4.25 pounds
per ton of lead.
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CABLE COVERING
Cables for communication over telephone and telegraph lines
and underground cables for distributing electrical power are
the two major types of electrical cables using lead coverings.
Since the purpose of any cable sheathing is protection for
wires and insulation from moisture and the corrosive attacks
of soil and atmosphere, lead has been a popular covering ma-
terial because it is chemically inert in the presence of many
corrosive acids and salts occurring naturally. In addition,
the plasticity and flexibility of lead permits coiling, easy
handling during installation, and minimizes the threat of
rupture.
In. the lead press technique for cable sheathing, the follow-
ing requirements prevail: (1) the lead must be pure, which
discourages any use of re-melted or scrap lead; (2) oxida-
tion is to be prevented during refilling and extrusion pro-
cesses; andj (3) a uniform, concentric sheath must be pro-
duced. The three main types of presses used to meet these
requirements a,re the vertical hydraulic press, the straight-
through press, and the continuous extrusion press.
In. the typical vertical press the lead tube is formed by
-------
-83-
forcing lead at a temperature just below 600 F into a cham-
ber surrounding the cable. The lead divides into two streams,
surrounds the point holder, and welds together on the under-
side. The mass of lead then flows to the die and emerges as
a lead tube. It is then spray cooled, passed through a water
trough, smeared with a thin layer of tallow, and wound on a
cable drum. The lead presses deliver 600 to 3, 000 tons
pressure and take 300 pounds to one ton of lead per charge.
Lead is melted in a lead pot adjacent to the press so that
molten lead can be run into the container by means of a
trough. This is often accomplished in a reducing atmos-
phere to minimize or prevent oxidation.
The straight-through press produces a sheath free from a
longitudinal seam. The press is set on a foundation inclined
downwards about 10 degrees from the horizontal. The lead
flows longitudinally and then radially inward toward the die.
The container may hold a lead charge of 1, 000 pounds and
the complete cycle in the press takes between 11 and 13
minute s.
The continuous extrusion press differs from the two presses
just described in one basic way. Vertical and straight-
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-84-
through presses are operated intermittently. When the lead
container is empty, the press is stopped to refill the contain-
er in preparation for the next sheathing operation. However,
in the continuous press insulated cable travels through a sta-
tionary tube surrounded by a revolving steel cylinder equipped
with screw threads which in turn is surrounded by a station-
ary barrel. In the press, molten lead is fed into one end
where it solidifies as it passes through the screw feed and
emerges as a seamless tube around.the cable. In this press
lead is not exposed to oxidation during container refilling,
there is no seam, and temperature can be controlled to pro-
duce an exact, uniform product. Continuous production is
usually more desirable and economically feasible.
Based on the information obtained from two cable covering
plants using cyclone collectors and bag filters, lead emis-
sions to the atmosphere ranged from 1. 5 to 5. 5 pounds per
ton of lead processed arid averaged 2. 0 pounds per ton. Emis-
sions were lead oxides' and silicates. The particle size
ranged from 0. 015 to 5 microns.
Based on the information regarding the two plants, lead
emissions to the atmosphere due to cable covering opera-
tions during 1970 totaled 50 tons.
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-85-
TYPE METAL,
Type metal alloys contain lead, antimony, and tin. Each of
these three elements is used to impart certain specific char-
acteristics. Lead is the base ingredient because it is plenti-
ful, relatively cheap, and alloys well with the other elements.
Antimony makes the.alloy harder and more wear-resistant,
lowers the melting point, and provides for some expansion as
the alloy passes from a liquid to a solid state. This last
characteristic causes the metal to be forced: into all the cracks,
crevices, and corners of the letter or design engraved into
the mold. Tin is added for toughness, delay of setting time,
a smooth finish, and increased fluidity of the alloy at all
temperatures.
At one time it was considered imperative that all type metals
be made from new or "virgin" metals; however, this concept
has changed. Today the preparation of type metal begins with
secondary lead from many sources including discarded bat-
teries, lead pipe, scrap-type metals, and drosses. As neces-
sary, the scrap materials are processed in reverberatory,
blast, and/or pot furnaces. Then the product is brought up
to specification by further metal additions prior to casting
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in the form of bars, ingots, pigs, or feeders.
The chemical composition of a type-metal alloy determines
its elementary or basic value, but to obtain satisfactory cast-
ing results the components must be homogeneously mixed to
form the perfect alloy. The alloy having the lowest melting
point is approximately 4 percent tin, 11. 5 percent antimony,
and 84. 5 percent lead. That is the formula for linotype
metal. All other type-metal alloys contain more tin and
more antimony, thus increasing the alloy's melting point.
Type metals are classified into four principal groups. Lino-
type alloys are used in machines casting type metal by the
line. The linotype metal must be of correct composition or
it could freeze in the portholes of the casting machine, since
operations are usually carried out at about 525 to 560 F.
Sterotype metal contains more tin and antimony and less lead
than linotype. The sterotype process produces a number of
like articles from the same mold known as a mat. The mat ,
is made from some other source such as a form of linotype
metal or a zinc engraving plate. It is one of the most sensi-
tive of the type metals and represents a v>ry large part of
all type-metal alloys used. Sterotyping differs from other
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typecasting processes mainly in: (1) size of the casting;
(2) flow of metal; and, (3) use of a nonmetallic surface
against which the metal is molded; Monotype alloys are
used where each single character is cast on a piece of metal.
Again there are increased amounts of tin and antimony.
Electrotype alloys are used for backing up "shells" of copper
or nickel which do the actual printing. These alloys all con-
tain less antimony and tin with increased amounts of lead
varying from 90 to 96 percent.
In a printing plant, such as a metropolitan newspaper, large
quantities of type metal are melted and remelted. The alloy
is used agiain and again from day to day, and it is also cir-
culated between the printer and the supplier. When a day's
printing is complete much of the metal used may be remelted
for type casting again the next day. Some cleaning is re-
quired and this can be accomplished by the printer. After
a certain amount of reuse, however, the type metal is re-
turned to the supplier for refining.
During this study a limited amount of information was ob-
tained regarding lead emissions due to the use of type metal.
Data was requested from nine large metropolitan newspapers,
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but only three answered with one furnishing emission data.
The one plant, during 1970, remelted 37, 000 tons of type
metal and purchased 104 tons to make up for losses. Tests
were conducted during April, 1971, and spectrographic
analyses showed that particulate emissions averaged 62 per-
cent non-combustible materials and 40 percent lead. Total
lead emissions were calculated to be 3.9 pounds per day,
or 1, 425 pounds per year.
The quantity of lead used in type metal during 1970 has been
reported to be 24,476 tons /., and the data from the one
newspaper indicates lead emissions are about 17 pounds per
ton of lead contained in the alloy. On this basis, lead emis-
sions in the United States during the year totaled about 200
tons.
1- Minerals Yearbook; Burea.u of Mines; 1970 Preprint.
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BRASS AND BRONZE
Lead is an alloying element in many brasses and bronzes.
In the various classifications o£ red and yellow brass, it is
found in quantities ranging from less than one to mor6 than
7 percent. In the high leaded bronzes, however, there may
be as much as 25 percent lead.
During the processing of Ijrass and bronze the metals may
be melted'together in a crucible, rotary, or reverberatory
furnace which may vary in size from several hundred to sev-
eral thousand pounds in capacity. The metal is poured and
cast at temperatures ranging from 1, 200 to 2,400 F, the
actual temperature depending upon the alloy. The molds
used to form slabs, cakes, and billets are cast iron, water-
cooled, and often copper-lined. After casting the shapes
may be rolled into plate, sheet, and strip; extruded into
rods, bars, and seamless tubes; or dra'.vn into wire. Final
finishing operations include flattening, straightening, slitting,
and cutting.
The emissions of lead and other pollutants vary in composi-
tion and concentration with the type of furnace, the alloy,
and the foundry practice as indicated by the data in Table IV.
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TABLE IV
BRASS-MELTING FURNACE
AND BAGHOUSE COLLECTOR DATA
Case
Furnace Data
Type of furnace
Crucible
Crucible
Low-frequency
induction
Fuel used
Metal melted
Composition of metal
melted, %
Copper
Zinc
Tin
Lead
Other
Melting rate, Ib/hr
Pouring temperature,
Slag cover thickness,
Slag cover material
Gas
Yellow brass
70.6
24.8
0.5
3.3
0.8
388
F 2, 160
in. 1/2
Glass
Gas
Red brass
85.9
3.8
4.6
4.4
1.3
343
2,350
1/2
Glass
Electric
Red brass
82.9
3.5
4.6
8.4
0.6
1, 600
2,300
3/4
Charcoal
Baghouse Collector Data
Volume of gases, cfm 9S 500
Type of baghouse Sectional
tubular
Filter material Orion
Filter area, ft2 3,836
Filter velocity, fpm 2. 47
Inlet fume emission
rate, Ib/hr 2. 55
Outlet fume emission
rate, Ib/hr 0. 16
Collection efficiency, % 93. 7
9,700
Sectional
tubular
Orion
3, 836
2.53
1.08
0.04
96.2
1, 140
Sectional
tubular
Orion
400
2.85
2.2*
0.086
96.0
Includes pouring and charging operations.
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-91-
Data obtained from companies processing approximately 10
percent of the brass and bronze produced during 1970 indi-
cates that lead emissions average about 4 pounds per ton of
lead contained in the product. Since the lead used in brass.
and bronze totaled 18, 927 tons during the year _/, lead
emissions to the atmosphere in the United States havp been
estimated at 40 tons.
1- Minerals Yearbook: Bureau of Mines; 1970 Preprint.
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BEARING METALS
The most common bearing metals containing lead include
copper-lead alloys, bronzes, and various babbitts which
are prepared in a manner similar to other alloys. Primary
lead may be melted in desired amounts with other metals,
or "secondary metals" may be refined and adjusted to spec-
ification.
The lead and tin alloys invented by Issac Babbitt are based
on the lead-antimony-tin, system containing 9 to 16 percent
antimony and up to 12 percent tin. The remainder is lead,
with very small amounts of copper and arsenic. The lower
cost of these alloys has been a primary factor in their popu-
larity and they have been used extensively in automotive and
diesel engines, outboard motors, lawn mowers, compressors,
and earth-moving equipment.
Even in situations where stronger materials are needed for
the actual bearings, babbitts are often employed as a thin
surface coating. For large bearings in electric motors,
turbines, blowers, and industrial equipment, finished babbitt
may be 1/16 to 3/8 inch thick. Careful attention must be
given to the details of each step in cleaning the bearing shell,
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rinsing, fluking, tinning, and. casting to secure a sound bond.
For smaller bearings and bushings used in fractional horse-
power motors, a bimetal strip is produced by casting babbitt
onto steel. The strip is then cut to size and the pieces formed
into finished bearings. Where bearings require very high
fatigue strength, three-layer strip bearings finfl use. They
consist of a low carbon steel backing, an intermediate layer
of metal, and a thin overlay of lead babbitt added by electro-
plating or precision casting.
Bronzes are used often for cast bushings since they combine
economy with adequate bearing properties as well as good
casting and machining characteristics. Leaded bronzes are
usually used for intermediate load applications such as elec-
tric motors, outboard motors, farm equipment, and railroad
cars. Tin bronzes are found in various heavy-duty applica-
tions. The very high strength bronzes appear in power shovels
and heavy earth-moving equipment as they display excellent
wear and impact resistance.
.Copper-lead alloy bearings are used principally in engines
where high fatigue strength and high temperature perform-
ance are required. Both main and .connecting-rod bearings
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in internal combustion engines for aircraft, automobiles,
trucks, and diesels use these alloys, but they are also found
in steam engines, electric motors, and turbines. These
bearings are often made with a steel backing and a thin bab-
bitt overlay. Premlxed powders of 65 to 76 percent copper
and 35 to 44 percent lead are usually the starting materials.
The powder is spread on a continuously moving steel strip,
sintered, rolled, resintered to improve the bond, and then
rolled to size and formed into bearings.
The information obtained from industry during this study
indicates that lead emissions resulting from bearing manu-
facture are negligible, even though air pollution control
equipment is rarely used in connection with melting and
alloying operations.
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METALLIC LEAD PRODUCTS
During the year 1970 approximately 122, 000 tons of lead
were used in the United States for terne metal, weights and
ballasts, caulking lead, plumbing supplies, roofing mater-
ials, casting metal, foil, collapsible tubes, sheet lead, gal-
vanizing, annealing, and lead plating V. In most instances
the lead was processed for these uses by melting and casting,
followed by mechanical forming operations such as extruding
or rolling. Sometimes it was necessary to melt the metal
more than once.
From the standpoint of lead emissions to the atmosphere,
it was determined during this study that most companies pro-
ducing metallic lead products do not use air pollution control
equipment unless it is required in connection with their other
manufacturing operations. Reports from these companies
indicate that their atmospheric emissions range from less
than 0. 5 to 4. 3 pounds per ton of lead processed. Based on
this information, the Contractor's estimate is that lead emis-
sions resulting from the manufacture of metallic lead products
1- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
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-96-
average 1. 5 pounds per ton of lead processed and emissions
in the United States during 1970 totaled 90 tons.
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-97-
MISCELLANEOUS
There were several uses of lead during 1970, which totaled
about 15, 000 tons, that have not been discussed elsewhere in
this report. They include ceramics, glass, plastics, fusi-
ble alloys, powdered lead greases, pesticides, and several
other lesser applications.
In the ceramics industry lead is used mostly in the form of
oxides and silicates in the manufacture of certain glasses,
glazes, and.vitreous enamels. Glass high in lead has a high-
er index of refraction^ greater density, lower thermal con-
ductivity, and greater chemical stability than unleaded glass.
These characteristics impart greater brilliance, resonance,
and toughness to the product. Lead also imparts its radia-
tion absorption quality in proportion to the quantity contained
in the glass. Optical glass, the finest glass tableware, most
glass for electrical purposes, and windows for radiation
shielding all contain large amounts of lead.
Lead is an important part of the composition of some fusible
alloys, such as those used in. sprinkler heads for spraying
water at predetermined temperatures and those used in
foundries to protect molds. It is also used as a vibration
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dampener. Lead-asbestos pads have been used for this pur-
pose under building and machinery foundations.
A growing use of lead compounds is in stabilizers for plas-
tics. Polyvinyl chloride is a material which softens when
heated and may be shaped into a variety of useful products.
Unfortunately, however, it not only softens but also begins
to degrade chemically. The stabilizers slow down this pro-
cess so that the material is practical for usage.
In pesticides, lead arsenate is the only lead compound of
commercial importance. Litharge, is reacted with arsenic
acid in the presence of an acetic acid catalyst to produce
lead arsenate. The batches of several thousand gallons are
heated to about 160 F and agitated for approximately 2 hours.
The resulting lead arsenate precipitate is subsequently pump-
ed to a drier from which the dry. powder is conveyed to stor-
age or the shipping department. Lead arsenate is sometimes
used in dry powder form and sometimes applied in solution.
Quantitative data are lacking regarding lead emissions to the
atmosphere due to the manufacture and miscellaneous uses
of lead.
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-99-
QTHER SOURCES OF LEAD EMISSIONS
WASTE OIL
It has been estimated that about 70 percent of the lead used
in gasoline additives is discharged from the engine directly
into the atmosphere, while the other 30 percent remains in
the engine and exhaust system as deposits or becomes a con-
taminant in the lubricating oil.
One report indicates that the quantity of waste lubricating
oil generated each year is currently in the order of 625 mil-
lion gallons, and that about 55 percent is either dumped or
used as road oil /. Most of the remaining 281 million gal-
lons is re-refined as lubricating oil or reprocessed to fuel
oil. It has been estimated that re-refining currently con-
2
sumes 100 to 125 million gallons _/; therefore, the amount
used as fuel oil is approximately 160 million gallons annually.
Since waste crankcase oil contains about one percent lead by
1- "Manual for Disposal of Liquid Petroleum Wastes'1; Sun
Oil Company; Philadelphia,, Pa. ; 1968.
2- Schmidt, P. F.; "Fuel Oil Manual"; 3rd Ed. ; Industrial
Press, Inc.; New York, N. Y. ; 1969.
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-100-
weight _/, the quantity used as fuel oil during 1970 con-
tained about 6, 400 tons of lead. Assuming that 50 percent
of the lead is discharged to the atmosphere during combus-
tion, the lead emissions during the year were; in the order
of 3, 200 tons.
1- Final Report of the API Task Force on Used Oil Disposal;
API Committee for Air and Water Conservation; American
Petroleum Institute; New York, N. Y. ; 1970.
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-101-
MUNICIPAL INCINERATION
Incineration is a combustion process and can be a source of
considerable air pollution unless carefully'controlled. Often
poor design, management, and operator judgement are re-
sponsible for excessive emissions.
The sources of lead emissions during refuse incineration
are refuse dumping and handling, smoke emissions around
openings and through cracks in furnace walls, and the par-
ticulate discharged from the stack. The magnitude of the
emissions is dependent principally upon the equipment de-
sign, the refuse composition, and the operating procedures.
If the furnace is designed so that complete combustion can
be achieved without undue difficulty, then it must be operated
within the design parameters. The refuse charging rate
must be maintained within the design range., the combustion
air must be sufficient for complete combustion, and the con-
dition of the refuse must be controlled within satisfactory
limits. Even though the incinerator equipment is properly
designed and operated, the emission rates will vary with the
ash content of the refuse and the efficiency of the dust col-
lecting system.
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Of the 190 million tons of solid wastes collected in 1967,
8 percent (about 15 million tons) was burned in municipal
incinerators _/. It is estimated that the quantity burned
in 1970 was 20 million tons. Tests at 2 municipal incinera-
tor locations indicate that uncontrolled lead emissions are
0,42 pound per ton of charge, and lead emissions controlled
by electrostatic precipitators average 0. 06 pound per ton /.
Calculations based on 50 percent control reveal that lead
emissions to the atmosphere due to municipal incineration
during 1970 totaled 2,400 tons.
0.42 x 107 0.06 x 107
2,000 "*~ 2,000 = 2'400
1- "Control Techniques for Particulate Air Pollutants";
NAPCA; Public Health Service Publ. No. AP-51; Jan,,
1969.
2- Source Test Nos. 71-CI-05 and 71-CI-ll.
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SEWAGE AND SLUDGE INCINERATION
A recent report, released for publication during 1972, con-
tains considerable information concerning the incineration of
sewage sludge at South Lake Tahoe, California; Barstow,
California; and Fairfax County, Lorton, Virginia. The sludge,
particulate, stack gas, scrubbing liquid, and ash were sampled
and analyzed for lead and other heavy metals. This data is in-
cluded in the report along with a description of the incinerator
equipment /.
Information from the report is shown as follows:
South Lake Tahoe,
California
Barstow,
California
Multiple hearth incinerator.
Design capacity - 900 Ibs. per hour
dry solids.
Control device - Single cross flow per-
forated plate scrubber (6" I^O pres-
sure drop);.
Test feed rate - 271 Ibs. per hour
average.
Particulate emissions - 0.423 Ibs. per
hour (total) average.
Lead in particulate - 1.4 percent aver-
age.
Fluidized bed reactor.
Design capacity - 500 Ibs. per hour
dry solids.
1- "Sewage and Sludge Incineration"; EPA Task Force;
Program Element B12043; Mar., 1972.
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-104-
Control device - Single cross^flow
perforated plate scrubber (4" t^O
pressure drop).
Test feed rate - 462 Ibs. per hour
average.
Particulate emissions - 0.742 Ibs. per
hour (total) average.
Lead in particulate - 0. 08 percent
average.
Fairfax County, Multiple hearth incincerator,
Lorton, -Virginia Design capacity - 2, 500 Ibs. per hour
dry solids.
Control device - Cyclone inertial jet
scrubber (2. 5" J^O pressure drop).
Test feed rate - 1, 223 Ibs. pe-jr hour
average.
Particulate emissions - 0. 198 Ibs. per
hour (total) average.
Lead in particulate - 0. 9 percent average.
Based on the above data, calculations indicate that lead emis-
sions from the 3 incinerators varied from about 0. 0026 to
0. 044 pound per ton of charge, averaging 0. 025 pound per ton.
Assuming that the efficiency of the scrubbers was 97 percent,
the emission factor was 0. 6 pound per ton (uncontrolled).
It is estimated that the sludge burning rate in the United
States during 1970 was about 2, 000 tons, per day /. Accord-
ingly, the lead emissions due to the burning of sludge are es-
timated on the basis of 10 percent control at approximately
200 tons for 1970.
1- Private communication with the Federal Water Pollution
Control Authority.
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COAL,
In order to estimate lead emissions to the atmosphere due
to the use of coal, information was obtained regarding the
quantity of coal-produced in various states, its lead content,
the quantity consumed during 1970, and the efficiency of dust
collecting equipment in use at coal-burning plants.
The Bureau of Mines, the Geological Survey, and others
have conducted numerous studies to determine the trace ele-
ment content of various coals; it has been found that lead
concentrations vary considerably from region to region. One
report covering the analyses of 827 samples of commercial
coals _/ indicates that those from areas near the Missouri
lead belt contain considerably more lead than those from
other parts of the country. Coal from Illinoisa Iowa, and
Missouri averages 31 to 33 ppm lead, while that from other
states averages from 0. 6 to 10. 5 ppm. As shown in Table V
this difference is significant. The Illinois coal a'ccounts for
nearly 43 percent of the lead in the coal produced during 1970.
1- Abernethy, R. F., Peterson, M. J., and Gibson, F. H.;
"Spectrochemical Analyses of Coal Ash for Trace Ele-
ments"; Bureau of Mines RI 7281; July, 1969.
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-106--
TABLE V
LEAD CONTENT OF COAL
MINED IN THE UNITED STATES
Aver'age
State Ash of
Dry Coal
Alabama
Ala s ka
Arizona
Arkansas
Colorado
Illinois
Indiana
Iowa
Kansas
Eastern Kentucky
Western Kentucky
Maryland
Missouri
Montana
New Mexico
North Dakota
Ohio
Oklahoma
Pennsylvania
Tennessee
Utah ^
Virginia
Washington
West Virginia
Wyoming
''Estimated
9.2
9.7
8.3
9.2
11.7
10.6
15.5
10.5
7.3
9.3
9.5
12.4
12.6
11.8
12.0
11. 8
10.0
9.7
7. 0
7.8
12.7
8.5
8.7
Average
Pb % in
ll Coal Ash1/
0. 0040
0.0040
0.0035
0.0031
0. 0279
0.0068
0. 0200
0.0100
0. 059
0.0069
0.0010
0.0267
0.0038
0.0040
0.0022
0. 0043
0.0052
0.0050
0.0024
0. 0078
0.0025
0.0058
0.0007
TOTAL
Average Pb
Content ol
Coal - pptn
3.7
7.0*
3.9
2.9
2.9
32.6
7.2
31.0
10.5
4.3
6.4
1.0
33.1
4.8
4.7
2.6
5. 1
7.0*
5.2
4.9
1.7
6.1
3.2
4.9
0.6
1970 Coal
Production
1000 Tons2/
20,560
549
132
268
-6, 025
65,119
22,263
987
1, 627
72, 502
52,803
1,615
4,447
3,447
7,361
5,639
55,351
2,427
80,491
8,237
4,733
35,016
37
144, 072
7,222
602, 930
Pb in
Coal
' Tons
76
4
1
1
17
2, 120
155
31
17
312
338
2
147
17
35
15
282
17
418
40
8
214
_
705
4
4, 976
1- Abernethy, R. F. , Peterson, M. J. , and Gibson, F. H. ; "Spectrochemical
Analyses of Coal Ash for Trace Elements"; Bureau of Mines RI 7281;
July, 1969.
2- "Advance Data on Coal - Bituminous and Lignite in 1970"; Mineral Industry
Surveys; Bureau of Mines; Feb. 7, 1972.
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-107-
Lead emissions to the atmosphere resulting from the use of
coal are primarily those that occur in connection with the pro-
duction of steam. During 1970 the electric utility companies
burned about 62 percent of the bituminous coal and lignite to
make steam for driving turbo-generators that procude elec-
tric energy. The remaining 38 percent was used mo'stly by
manufacturing and mining companies to make steam for vari-
ous heating and processing operations /.
Currently most of the steam generated by burning coal is
produced in relatively large combustion units that are equipped
with a dust collecting system. Electrostatic precipitators
and mechanical cyclone collectors are the types of equipment
used in nearly every plant. As the coal is burned, a consider-
able portion of the ash is carried upward with the flue gas
through the boiler to the dust collection system, where most
of the ash is removed before the flue gas is discharged to the
atmosphere.
Information obtained from the Federal Power Commission in
the form of a computer print-out shows the design efficiency
1- "Advance Data on Coal - Bituminous and Lignite in 1970";
Bureau of Mines; Mineral Industry Surveys; Feb. 7, 1972.
-------
-108-
of dust collectors and the quantity of coal consumed at elec-
tric utility plants -in the United States. Using that informa-
tion, average overall dust collection efficiencies have been
estimated and calculations have been made based on:
(a) 602, 930, 000 tons of bituminous coal and lignite
produced during 1970, containing 4, 976 tons of
lead (see Table V);
(b) 517, 158, 000 tons of bituminous coal and lignite
consumed during 1970 /, containing 4, 270 tons
of lead (based on Table V);
(c) fly ash 65 percent of total ash;
(d) 85 percent average overall dust collection efficiency;
(e) 90 percent application of control.
The lead emissions calculated in this manner totaled 650 tons
during 1970.
4, 270 x 0. 65 [l - (0. 85 x 0. 90)J = 650
1- "Advance Data on Coal - Bituminous and. .Lignite in 1970";
Bureau of Mines; Mineral Industry Surveys; Feb. 7, 1972.
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-109-
OIL
While this study was in progress several large oil refining
companies were contacted for the purpose of obtaining reli-
able data regarding the lead contained in the various foreign
and domestic fuel oils- used in the United States. Unfortu-
nately, nothing was available concerning the oil used in 1970;
however, some useful information was obtained frorn one
company concerning the oil refined in 1967.
During refining, the metallic elements (including lead) found
in crude oil concentrate in the residual fuel. Data compiled
in 1967 show that residual oil (No. 6 fuel oil) produced from
domestic crude averaged 20 ppm of lead, while that produced
from foreign crude averaged 0. 8 ppm _/. This data repre-
sents the average of numerous tests of products of one oil
refining company rather than industry averages, and does
not include low-sulfur residuals from Libyan or Nigerian
crudes.
The residual oil consumed in the United States during 1970
1- Private communication.
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-110-
was 804 million barrels _/. Approximately 72 percent (580
million barrels) was produced from foreign crude oils and
28 percent (224 million barrels) from domestic crudes.
Based upon the above lead concentrations and an average
weight of 340 pounds per barrel, the residual oil from for-
eign crudes contained about 80 tons of lead and that from
domestic crudes about 760 tons.
Substantially different results were obtained, however, when
using data from another source. Out of 101 samples of do-
mestic crude, 92 samples contained from 0.0003 to 11.4
ppm of lead and 9 samples contained no lead. The average
2
for the 101 samples was 0.29 ppm', of lead /. The domestic
production of crude oil during 1970 was 3,350 million bar-
rels _/. Calculations using these figures indicate that do-
mestic crude contained 165 tons of lead.
A third source of information gives emission factors in
1- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
2- Horr, C. A. et al; "Uranium and Various Other Metals
in Crude Oils"; Geological Survey Bulletin 1100; 1961.
3- Mineral Industry Surveys; "Sales of Fuel Oil and Kero-
sine in 1970"; Oct. 1, 1971.
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-Ill-
terms of pounds of lead per million gallons of fuel oil for
distillate oil fired in residential units and for residual oil
fired in commercial boilers. An average of 3 tests burning
distillate oil indicates that lead emissions are about 3 pounds
per million gallons of fuel (0. 1 pound per 1,000 bbls), and 3
tests burning residual oil show 1. 5 pounds of lead per mil-
lion gallons (0.06 pound per 1,000 bbls) _/. Based on
these emission factors, the 927 million barrels of distil-
2
late oil used in 1970 __/ resulted in lead emissions totaling
about 65 tons, and the 804 million barrels of residual oil
accounted for lead emissions of 25 tons.
The total lead emissions due to the use of fuel oil in the
United States during 1970 are estimated by the Contractor
at 90 tons.
1- Levy, A., Miller, S. E. , Barrett, R. E. , Schulz, E. J.,
Melvin, R. H. , Axtman, W. H., and Locklin, D. W. ; "A
Field Investigation of Emissions from Fuel Oil Combustion
for Space Heating"; Battelle - Columbus; Presented at
American Petroleum Institute Committee on Air and Water
Conservation Meeting at Columbus, Ohio; Nov. 1, 1971.
2- Mineral Industry Surveys; "Sales of Fuel Oil and Kerosine
in 1970"; Oct. 1, 1971.
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IRON AND STEEL
There are numerous documents that contain information re-
lated to lead emissions to the atmosphere from steel mills.
It is thought that most of the emissions occur due to the use
of iron ore that contains trace amounts of lead, the use of
lead-bearing scrap, the production of ferromanganese, and
the manufacture of leaded steel alloy. There are direct
references concerning the analyses of particulate samples
collected at the discharge of open-hearth, electric, and basic
oxygen furnaces. Also., there is information showing the
quantity of particulate emitted from various steelmaking
operations.
It is estimated that dusts containing more than 10, 000 tons
of lead are produced by the steelmaking industry each year.
A Bureau of Mines report states that 340 dust samples from
48 operators were analyzed for metal content. The lead con-
tained in the dust from open-hearth, electric, and basic opcygen
furnaces averaged 0. 8, 2.0, and 0. 4 percent, respectively /-
1- Barnard, P. G. et al; "Recycling of Steelmaking Dusts";
Bureau of Mines Solid Waste Program; Technical Pro-
gress Report - 52; Feb., 1972.
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113-
It was also noted that electric furnace dusts have a wider
range composition, due to the variation in lead content of the
100 percent scrap heats. The analyses of dusts from 18
electric furnaces showed that the contained lead varied from
0. 17 to 5. 7 percent.
Emission factors have been determined for particulate dis-
charged from steelmaking operations _/ and are shown as
follows:
Blast Furnace - 160 Ibs/ton (uncontrolled)
Open-Hearth - 17 Ibs/ton (uncontrolled)
Basic Oxygen - 46 Ibs/ton (uncontrolled)
Electric Arc - 9 Ibs/ton (uncontrolled)
Sintering - 42 Ibs/ton (uncontrolled)
Scarfing - 20 Ibs/ton (uncontrolled)
Based on the above data, emission factors for lead are:
Open-Hearth - 0. 14 Ibs/ton (uncontrolled)
Basic Oxygen - 0. 18 Ibs/ton (uncontrolled)
Electric Arc - 0. 18 Ibs/ton (uncontrolled)
During 1970 the open-hearth steel production was 48 million
tons /. Based on the above emission factor and 70 percent
1- "Compilation of Air Pollutant Emission Factors (Revised)";
U. S. Environmental Protection Agency; Research Tri-
angle Park, N. C. ; Office of Air Programs; Publ. No.
AP-42; Feb., 1972.
2- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
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-114-
control, the lead emissions were about 1, 000 tons.
Basic oxygen steel production was 63. 3 million tons during
1970 /. At 99 percent control, the lead emissions were
nearly 60 tons during the year.
Electric arc steel production for 1970 was 20. 2 million
.tons _/. Based on an emission factor of 0. 18 Ibs/ton and
78 percent control, the lead emissions during the year
totaled 400 tons.
Due to lack of data regarding the lead content of dust from
blast furnace, sintering, and scarfing operations, the lead
emissions from these sources have not been estimated. It
does seem likely, however, that the total for these might be
as much as the total from the open-hearth, electric, and
basic oxygen furnaces.
1- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
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GREY IRON FOUNDRIES
During this study spectrographic analyses of dust samples
from three iron foundries were examined. Lead was con-
tained in each sample, the amount ranging from 0. 5 to 2. 0
percent, and averaging 1.2 percent _/-
The cupola is the most popular method for producing cast
iron. The rate of particulate emissions from this type of
furnace has been reported as 4 to 26 pounds per ton of pro-
cess weight not including emissions from materials handling,
charging, or other non-melting operations. A cupola emis-
sion factor of 17 pounds per ton of metal charged (uncontrolled)
2
has been determined _/.
Based on the information obtained from industry, the par-
ticulate emission factor is estimated at 22 pounds per ton of
process weight, including melting and non-melting operations.
The degree of emission control is estimated at 25 percent.
Calculations show that with 1. 2 percent lead in the particulate,
1- Private communication.
2- "Compilation of Air Pollutant Emission Factors (Revised)":
U. S. Environmental Protection Agency; Research Tri-
angle Park, N. C. ; Office of Air Programs; Publ. No.
AP-42; Feb., 1972.
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-116-
the emission factor is 0. 26 pound of lead per ton of process
weight (uncontrolled).
During 1970 the production at grey iron foundries was re-
ported as 24 million tons /; therefore, lead emissions to
the atmosphere totaled 2,300 tons.
1- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
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FERROALLOYS
During this study a search revealed that very little data is
available regarding lead emissions resulting from ferro-
alloy processing. Emission factors for particulate have been
established and studies have been conducted covering the ef-
fectiveness, cost, and use of air pollution controls. The area
where more information is needed concerns the quantity of
lead in the particulate.
The effluent from a ferromanganese blast furnace is reported
to be a greater air pollution probelm than that from an iron
blast furnace _/. It is said to be the most prolific pollution
producer of any of the metallurgical processes /. A par-
ticulate emission factor of 410 pounds pej ton (uncontrolled)
has been established for the ferromanganese blast furnace
operations, while the emission factor for electric furnaces is
45 pounds per ton _/. For silicomanganese production in
1- Thring, N. W. and Sarjant, R. J. ; "Dust Problems of the
Iron and Steel Industry"; Iron and Coal Traders Rev. ;
J/74; Mar. 29, 1957.
2- Wurts, T. C. ; "Industrial Sources of Air Pollution -
Metallurgical"; Public Health Service Publ. No. 654; 1959.
3- "Compilation of Air Pollutant Emission Factors .(Revised)11;
U. S. Environmental Protection Agency; Research Tri-
angle Park, N. C. ; Office of Air Programs; Publ. I\:>.
AP-42; Feb., 1972.
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-118-
electric furnaces the emission factor is 195 pounds per ton /.
Information obtained from industry indicates that typical emis-
sions from silicomanganese furnaces contain about 0.45 per-
cent lead, while those from ferromanganese furnaces contain
2
0. 90 percent _/.
During 1970 the production of silicomanganese and ferro-
•3
manganese / was as follows:
Silicomanganese - 119, 000 tons
Ferromanganese
Blast Furnace - 501, 000 tons
Electric Furnace - 334, 000 tons
Based on the above information the lead emissions for 1970
are estimated as follows:
Lead
Emissions
Production of silicomanganese
(50 percent control) - 25 tons
Production of ferromanganese
Electric Furnace (40 percent control) - 40 tons
Blast Furnace (99 percent control) - 10 tons
75 tons
1- "Compilation of Air Pollutant Emission Factors .(Revised)";
U. S. Environmental Protection Agency; Research Tri-
angle Park, N. C. ; Office of Air Programs; Publ. No.
AP-42; Feb., 1972.
2- Private communication.
3- Minerals Yearbook; Bureau of Mines; 1970 Preprint.
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-119-
CEMENT PLANTS
There are^four basic production steps in the manufacture of
cement. They include quarrying, size reduction of the lime-
stone rock, clinker production, and finish grinding. After
quarrying, the rock is first crushed in primary and second-
ary crushers, then it goes through the grinding operation.
Next, the raw materials are dried and calcined in a kiln to
produce a cement clinker. Finally, the clinker is ground
with gypsum and packaged for shipment.
Cement may be manufactured by the wet or dry process, but
the principal difference is in the grinding step. In the wet
process, water is introduced before grinding and the mater-
ial is handled in a slurry until it reaches the kiln.
Although the kilns, dryers, and crushers are the major
sources of particulate emissions, dust is produced in nearly
every manufacturing step. Throughout processing the raw
material is transported from point to point by conveyors.
Even though hoods may be used over loading, unloading, and
transfer points, the conveying equipment is a source of sub-
stantial emissions.
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-120-
It has been determined that uncontrolled particulate emis-
sions from the wet and dry processes are 44 and 64 pounds
per barrel of cement, respectively /. The average is,
therefore, considered to be 54 pounds per barrel. The analy-
ses of dust collected during source testing at four cement
plants indicates that the lead content averages about 450
pprri _/. The cement produced during 1970 was 407 million
barrels.
Based on the above* data and an estimated 90 percent control,
the lead emissions during 1970 totaled 500 tons.
1- "Compilation of Air Pollutant Emission Factors (Revised)";
~U. S. Environmental Protection Agency; Research Triangle
Park, N. C. ; Office of Air Programs; Publ. No. AP-42;
Feb., 1972.
2- Source Test Nos. 71-MM-01, 71-MM-D2,71-MM-03S and
71-MM-05.
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-121-
UPDATING OF EMISSION ESTIMATES
Since the scope of work for this study specifically excluded
field testing, the emission estimates presented are the re-
sults of calculations based on: (1) test data where available;
(2) reports from industry; (3) direct observations; or,
(4) a combination of published data and assumptions. It is
believed that the most accurate estimates are those based
on the test data and the industry reports; however, in most
instances the number of tests are limited to two or three
and their average may not always be representative of the
average for the industry.
The estimates based on test data include those for:
Municipal Incineration
Sewage and Sludge Incineration
Distillate Oil Combustion
Residual Oil Combustion
Iron and Steel Production
Grey Iron Foundries
Cement Plants
It is recommended that more source tests be conducted for
all categories, except Iron and Steel Production.
The emission estimates based on industry reports include:
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-,122-
Primary Lead
Secondary Lead
Lead Oxide Production
Storage Batteries
Gasoline Additive Manufacture
Pigments
Cable Covering
Type. Metal
Brass and Bronze
The estimates for primary and secondary lead, lead oxide
production, storage batteries, and gasoline additive manu-
facture are believed to be reasonably accurate. They are
based on information obtained from a large percentage of the
producers and, therefore, it is doubtful that updated esti-
mates would yield more accurate results. On the other hand,
information obtained from manufacturers of pigments, cable
covering, type metal, and brass and bronze was limited.
.Additional information in the form of source test data would
unquestionably improve the accuracy of those estimates.
With respect to mining and milling, the emission factor
shown in this report was determined by direct observation,
Several plants were visited while milling was in progress.
In addition, some information was obtained during conversa-
tions with the operating personnel. It is recommended that
source tests be conducted.
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-123-
For lead emissions resulting from primary copper and zinc
smelting, solder manufacture, waste oil and coal combustion,
and ferroalloy production, certain assumptions were made to
supplement published information. Again, source testing is
recommended as the method for improving the accuracy of
emission estimates.
-------
BIBLIOGRAPHIC DATA '• Report No.
SHEET
3. Recipient's Accession No.
4. Title and Subtitle
Emission Study of Industrial Sources of Lead Air Pollutants
1970
5- Report D;
port Date
April 1973
6.
7. Author(s)
W. E. Davis
5. Performing Organization Rept. j
No. i
9. Performing Organization Name and Address
W. E. Davis
9726 Sagamore Road
Leawood, Kansas
10. Project/Task/Worlc Unit No.
11. Contract/Grant No.
68-02-0271
12. Sponsoring Organization Name and Address
Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
13. Type of Report & Period
Coveted
Final 1970
14.
15. Supplementary Notes
16. Abstracts
Emission Study of Industrial Sources of Lead Air Pollutants has been prepared to pro-
vide reliable information regarding the nature, magnitude, and extent of lead emissions
from industrial sources in the United States for the year 1970.
Background information concerning the basic characteristics of the lead industry has
been assembled and included. Brief process descriptions, limited to areas closely
related to existing or potential atmospheric losses of lead, are included. Lead
emissions and emission factors are presented.
17. Key Words and Document Analysis. 17o. Descriptors
Inventory
Atmospheric Emissions
Lead
Lead Industry
Pollutant
Lead Emissions
Lead Emission Factors
17b. Identifiers/Open-Ended Terms
17c. COSATI Field/Group
13B
18. Availability Statement
Unlimited
19. Security Class (This
Report)
UNCLASSIFIED
20. Security Class (This
Page
UNCLASSIFIED
21. No. of Pages
123
22. Price
FORM KIT1S-33 (REV. 3-721
USCOMM.OC
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