NATIONAL INVENTORY
OF SOURCES
AND EMISSIONS:
ZINC - 1969
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
-------
APTD-1139
NATIONAL INVENTORY
OF
SOURCES AND EMISSIONS:
ZINC - 1969
by
W. E. Davis § Associates
9726 Sagamore Road
Leawood, Kansas
Contract No. 68-02-0100
EPA Project Officer: C. V. Spangler
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, N.C. 27711
May 1972
-------
The APTD (Air Pollution Technical Data) series of reports is issued by
the Office of Air Quality Planning and Standards, Office of Air and
Water Programs, Environmental Protection Agency, to report technical
data of interest to a limited number of readers. Copies of APTD reports
are available free of charge to Federal employees, current contractors
and grantees, and non-profit organizations - as supplies permit - from
the Air Pollution Technical Information Center, Environmental Protection
Agency, Research Triangle Park, North Carolina 27711 or may be obtained,
for a nominal cost, from the National Technical Information Service,
5285 Port Royal Road, Springfield, Virginia 22151.
This report was furnished to the Environmental Protection Agency
in fulfillment of Contract No. 68-02-0100. The contents of this report
are reproduced herein as received from the contractor. The opinions,
findings and conclusions expressed are those of the author and not
necessarily those of the Environmental Protection Agency. The report
contains some information such as estimates of emission factors and
emission inventories which by no means are representative of a high
degree of accuracy. References to this report should acknowledge the
fact that these values are estimates only.
Publication No. APTD-1139
11
-------
PREFACE
This report was prepared .by W.. E. Davis & Associates pur-
suant to Contract No. 68-02-0100 with the Environmental
Protection Agency, Office of Air Programs.
The inventory of atmospheric emissions has been prepared
to provide reliable information regarding the nature, mag-
nitude, and extent of the emissions of zinc in the United
States for the year 1969.
Background information concerning the basic characteristics
of the zinc 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 pro-
ducers and about twenty percent of the companies in each
major emission source group to obtain the required informa-
tion. It was known that published data concerning the atmos-
pheric emissions of zinc were virtually nonexistent, and con-
tacts with industry ascertained that atmospheric emissions
were not a matter of record. The zinc emissions and
ill
-------
emission factors that are presented are based on the summa-
tion of data obtained from production and reprocessing com-
panies. Additional information was acquired during field
trips to inspect the air pollution control equipment and ob-
serve processing operations.
IV
-------
ACKNOWLEDGEMENTS
This was an industry oriented study and the authors express
their appreciation to the many companies and individuals in
the zinc 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 and State 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.
-------
CONTENTS
SUMMARY 1
Emissions by Source 2
Emissions by Regions 3
Emission Factors 4
SOURCES OF ZINC 6
MATERIAL FLOW THROUGH THE ECONOMY ... 8
Chart 9
USES AND EMISSIONS OF ZINC
Mining and Milling 10
Metallurgical Processing 12
Secondary Zinc Production 21
End Product Uses of Zinc 27
Zinc-Base Alloys . 28
Zinc Coatings 32
Galvanizing 32
Sherardizing 38
Electrolytic Deposition 40
Brass and Bronze 41
Zinc Oxide 44
Production 44
Rubber 46
Photocopying 48
Paints 49
Other 51
Rolled Zinc 53
Zinc Sulfate 57
Miscellaneous 58
VI1
-------
OTHER SOURCES OF ZINC EMISSIONS
Coal 60
Oil 64
Iron and Steel . 66
Blast Furnaces 66
Open-Hearth Furnaces 67
Basic Oxygen Furnaces 68
Electric Furnaces 69
Foundries 70
Incineration 72
UPDATING OF EMISSION ESTIMATES 74
Vlll
-------
TABLES
Table I Emissions by Source • . . . 2
Ta.ble II Emissions by Regions 3
Table III Emission Factors 5
Table IV Typical Zinc Roasting Operations .... 14
Ta.ble V Zinc Recovered from Scrap Processed
in the United States During 1969 ..... 22
Table VI Chemical Analysis of the Fumes
Collected by a Baghouse and by an
Electric Precipitator from Zinc-
Galvanizing Kettles 36
Table VII Brass-Melting Furnace and Baghouse
Collector Data 43
Table VIII Average Minor Element Contents of
Coal from Various Regions of the
United States - ppm 63
Table IX Residual Fuel Oil Data 65
FIGURES
Figure I Ma.te.rial Flow Through the Economy ... 9
Figure II Electrolytic Zinc Plant Flow Diagram . . 16
-------
-1-
SUMMARY
The flow of zinc in the United States has been traced and
charted for the year 1969 (Figure I). The consumption was
1, 797, 000 tons, while primary and secondary production
totaled 1, 417, 000 tons. Imports and exports were 354, 000
and 43, 000 tons, respectively. Ore used directly in process-
ing was 127, 000 tons.
Emissions to the atmosphere during the year were 159,922
tons (Table I). About 31 percent of the emissions resulted
from the metallurgical processing of zinc, more than 30 per-
cent from the production of iron and steel, and nearly 18 per-
cent from the incineration of refuse. The production of zinc
oxide, the wear of rubber tires, and the combustion of coal
were also significant emission sources.
Emission estimates for mining, ^production of primary and
secondary zinc, manufacture of zinc-base alloy products,
and the production of zinc oxide are based on unpublished
data obtained from industrial sources.
-------
TABLE I
Source Category
Mining and Milling
Metallurgical Processing
Secondary Production
End Product Uses
Other Emission Sources
EMISSIONS BY SOURCE
1969
Source Group
Zinc-Base Alloys
Zinc Coatings
Brass and Bronze
Zinc Oxide
Zinc Oxide Production
Rubber Tires
Photocopying
Paint
Other
Zinc Sulfate
Miscellaneous
Coal
Oil
Iron and Steel
Blast Furnace
Open-Hearth Furnace
Basic Oxygen.Furnace
.Electric Furnace -
Foundries
Incineration
Emissions - Tons
72
50,000
3,800
23,270
3: 000
950
180
8, 100
8,400
1, 500
10
1,000
30
100
4, 310
450
1, 070
39,000
900
7,400
1, 700
27,950
82,780
Emissions
%
31. 3
2.4
14. 6
51. 7
TOTAL
159,922
100. 0
-------
-3-
TABL£ II
EMISSIONS BY REGIONS
Tons
Region No. 1 19, 800
Region No. 2 47, 200
Region No. 3 52, 500
Region No. 4 40, 422
TOTAL 159,922
Region No. 1
Arizona
California
Colorado
Idaho
Montana
Nevada
New Mexico
Oregon
Utah
Washington
Wyoming
Illinois
Indiana
Iowa
Kansas
Alabama
Arkansas
Delaware
Florida
Georgia
Kentucky
Connecticut
Maine
Massachusetts
Region No. 2
Michigan
Minnesota
Missouri
Nebraska
Region No. 3
Louisiana
Maryland
Mississippi
North Carolina
Oklahoma
South Carolina
Region No. 4
New Hampshire
New Jersey
New York
North Dakota
Ohio
South Dakota
Wisconsin
Tennessee
Texas
Virginia
West Virginia
District of
Columbia
Pennsylvania
Rhode Island
Vermont
-------
-4-
EMISSION FACTORS
The emission factors presented herein are the best currently
available. They were determined through a combination of
methods consisting of: (1) direct observation 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.
-------
-5-
TABLE III
EMISSION FACTORS
Mining and Milling
Metallurgical Processing
Electrolytic Plants
Vertical-Retort Plants
Horizontal-Retort Plants
Secondary Production
End Product Uses of Zinc
Zinc-Base Alloys
Zinc Coatings
Brass and Bronze
Zinc Oxide Production
Rubber Tire Wear
Other Emission Sources
Coal
Oil
Blast Furnaces
Open-Hearth Furnaces
Basic Oxygen Furnaces
Electric Furnaces
Foundries
0. 2 Ib/ton zinc mined
60. 0 Ib/ton of product
80. 0 Ib/ton of product
170. 0 Ib/ton of product
20. 0 Ib/ton of zinc produced
10. 0 Ib/ton of zinc processed
4. 0 Ib/ton of zinc processed
2. 0 Ib/ton of zinc content
60. 0 Ib/ton of zinc oxide
4. 2 Ib/million miles
17. 0 lb/1, 000 tons of coal burned
1. 4 lb/ 1, 000 bbls of oil burned
0. 02 Ib/ton of pig iron produced
1. 3 Ib/ton of steel produced
0. 03 Ib/ton of steel produced
0. 74 Ib/ton of steel produced
0. 18 Ib/ton of process weight
-------
-6-
SOURCES OF ZINC
Zinc is a relatively soft bluish-white metal that is widely
distributed in the earth's crust in the form of its various
minerals. It is usually found in nature as the sulfide and
occurs in small quantities in nearly all igneous rocks. The
principal mineral is sphalerite, commonly called zinc blende,
which is resinous in appearance with its color varying from
light tan to black.
Most other zinc minerals have probably been formed as ox-
idation products of the sulfide. These minerals include
zincite, goslarite, smithsonite, hemimorphite, willemite,
franklinite, and hydrozincite. They are usually minor sources
of zinc; however, franklinite and zincite are major deposits
in the ores of Sussex County.. New Jersey.
Zinc minerals are commonly associated with lead minerals
and the ratio of zinc to lead varies over a wide range. In
the southeastern part of Missouri the ratio is in the order of
]0 percent zinc and 90 percent lead, but in the southwestern
part of Missouri the ratio is about 82 percent zinc to 18 per-
cent lead. Other minerals that are associated with zinc are
*.
calcite, dolomite, pyrite, greenockite, quartz, chalcopyrite,
and barite.
-------
-7-
In the United States ores containing zinc are mined in Ari-
zona, California, Colorado, Idaho, Illinois, Kansas, Missouri,
Montana, New Jersey, New Mexico, New York, Oklahoma,
Pennsylvania., Tennessee, Utah, Virginia, Washington, Wis-
consin, and to a lesser extent in several other sta.tes. About
44 percent of the zinc from domestic mines during 1969 was
from states west of the Mississippi River. Approximately
63 percent was contained in zinc ores; 18 percent in lead-
zinc ores; 9 percent in lead ores; 6 percent in copper-lead-
zinc ores; and 4 percent in all other ores.
During 1969 zinc produced from domestic ores accounted
for about 31 percent of the United States' consumption; zinc
from foreign ores about 34 percent; imported sla.b zinc a-
bout 18 percent; and secondary zinc about 1? percent. The
foreign ores and concentrates were' principally from Canada,
Mexico, and Peru. The major pa.rt of the imported slab
zinc was from Canada., Japan, Australia, Peru, Belgium-
Luxembourg, and Mexico.
-------
-8-
MATERIAL FLOW THROUGH THE ECONOMY
The consumption of zinc in the United States during 1969 was
1, 797, 000 tons /, which was nearly 4 percent higher than
in 1968. The sources of supply were principally primary
slab zinc (1,041,000 tons - Zn content) recovered from for-
eign and domestic ores, secondary zinc (376, 000 tons - Zn
content) reclaimed from old and new scrap, a.nd imports of
metal and compounds (354,000 tons - Zn content) / as shown
in Figure I.
The largest use of zinc was in zinc-base alloys. About 33
4
percent was utilized for this purpose, principally in diecast-
ing alloy. The second largest quantity, nearly 27 percent,
was consumed by the galvanizing industry. The amount en-
tering into brass and bronze production was 21 percent,
while that in zinc oxide was only 10 percent.
1- Minerals Yearbook; Bureau of Mines; 1969.
-------
ZINC
MATERIAL FLOW THROUGH THE ECONOMY - 1969
(Thousand Tons - Zn Content)
SOURCES USES
1Z7 _ 604
ORE USED DIRECTLY
1.041
PRIMARY ZINC
354
IMPORTS
17
STOCKS
EXPORTS
75
UNACCOUNTED
376
SECONDARY ZINC
A
1,797
ALLOYS
476
GALVANIZING
376
BRASS AND BRONZE
176
ZINC OXIDE
49
ROLLED ZINC
ZZ
ZINC SULFATE
94
MISCELLANEOUS
CONSUMER
1
SC_R A_P__ (Refer ence_ Table V_) ,
-------
-10-
USES AND EMISSIONS OF ZINC
MINING AND MILLING
Even though mining methods vary somewhat with the type of
ore body, the basic operations of ore removal, ore handling,
and crushing are essentially the same. Following crushing,
the usual practice is for all of the ore to be ground in ball
mills and separated by flotation; however, certain western
ores require a different treatment. They contain lead and
zinc too intimately mixed for satisfactory separation by flo-
tation and the final step in this case involves sulfuric acid
leaching, usually at a.n electrolytic zinc plant.
From the standpoint of emissions to the atmosphere, the
principal losses during mining and milling operations are
those that occur due to blasting, ore handling, crushing,
and the wind loss from tailings. During grinding and flota-
tion or leaching, the ore is wet and atmospheric emissions
are negligible.
While this study was in progress, ma.ny. companies were
contacted concerning their mining methods and the zinc emis-
sions that occur during mining and milling. Even though
-------
-11
records were not available concerning losses to the a.tmos-
phere, several emission sources were observed at each lo-
cation that was visited.
Emissions''from Mining and Milling - Zinc emissions to
the atmosphere from sources of mining and milling are es-
tima.ted by the Contractor at 0.2 pound per ton of zinc mined.
The actual zinc content of the ore mined in the United States
during 1969 was about 723,000 tons, and zinc emissions to
the atmosphere were 72 tons.
-------
-12-
METALLURGICAL PROCESSING
In the United States, during 1969, zinc was produced at 14
primary slab zinc plants. Those p!a.n!:s produced primary
zinCj secondary zinc, and va.rious zinc compounds including
large quantities of zinc oxide. Zinc was also reclaimed
from old and new scrap at 13 secondary slab zinc plants,
and from lead smelter slag at 5 sla.g-fuming plants.
The prima.ry zinc smelters are all somewhat different, but
are usually classified according to 3 general types. Five of
them are electrolytic plants, 5 others are horizontal-retort
type distillation facilities, and the rema.ining 4 are 'vertical-
retort distillation units.
Rega.rdless of the type of recovery process employed at the
different plants, many of the operations are similar. Roast-
ing in some form is practiced on all zinc sulfide concentra.tes
and drying prior to roasting is often required. The exothermic
heat of reaction, of the sulfur in the ore with the oxygen of the
air is the source of heat for processing; however, natural
gas is used as auxiliary fuel, principally for plant start-up
purposes. Typically, zinc recovery procedures include ore
and concentrate unloading from railroad cars to open storage
-------
piles, loading and conveying from storage to dryers, convey-
ing from dryers to stora.ge bins, and on to roasters. Several
types of dryers and roasters a.re used at the va.rious locations.
Of the several types of roasters listed in Table IV, the Ropp
roaster is the oldest currently used in the zinc industry. It
is a long, narrow, mechanically rabbled reverberat.ory furn-
ace divided into 2 parallel hearths. The multiple hearth is
the next oldest type and it. is about 20 or 25 feet in diameter
containing from 7 to 16 hearths. Both, roasters operate at
relatively low temperatures;, discharging la.rge volumes of
off gas.
Suspension and fluid-bed roasters are more recent develop-
ments and they operate at higher temperatures. The sus-
pension roa.ster consists of a. refractory-lined vessel with a
.Large combustion space in the top and 4 hea.r'hs in the bor.tom
portion. The process resembles the burning of pul\ e.r.i zed
coal. Ever, though the offgas volume is re.latively low, there
is a large amount, of dust discharged from the suspension
roa.ster. Fluid-bed roasters also have ?.hese same operating
cha.racteri sties.
After roasting at electrolytic plants., the concentrate is
-------
-14-
TABLE IV
TYPICAL ZINC ROASTING OPERATIONS (1)
Feed
Type of Roaster pera mg Capacity
TemP' F ton/day
Multihearth 1,200-1,350 50-120
Multihearth (2) 1,600-1,650 250
Ropp (3) 1,200 40-50
Dust in
„,, Offgas
Offgas *
% of Feed aU2 /0
5-15 4.5-6.5
5-15 4.5-6.5
5 0.7-1.0
Fluid bed (4)
(Dorr. -Oliver)
Fluid bed (2)
(Dorr-Oliver)
Fluid bed
(Lurgi)
Suspension
Fluid column
1, 640
1, 650
1,700
], 800
1,900
140-225
240-350
240
120-350
225
70-80
75-85
50
50
17--18
7-8
10-12
9-10
8-12
11-12
(1) Dead roast except where noted otherwise.
(2) First stage is a partial roast in. multihearth; second stage
is a dry -feed dead roast in Dorr-Oliver fluid bed.
(3) Partial roa.st.
(4) Slurry feed.
"Systems Study for Control of Emissions Primary Nonferrous
Smelting Industry"; Vol. I; Arthur G. McKee & Co. , San
Francisco, Calf. ; June, 1969.
-------
-15-
leached with dilute sulfuric acid as shown in Figure II to
form a zinc sulfa.te solution. Then the pregnant liquor is
purified and piped to electrolytic cells, where the zinc in
the liquor is deposited on aluminum cathodes. At intervals
the cathodes are removed from the cells and stripped of
zinc. After the pregnant liquor is purified, the residue that
remains is washed, dewatered, and dried as it is prepared
for the recovery of other metals.
After roasting at distillation plants, sintering is used mainly
to agglomerate the roaster calcine. The sintering machines
ha.ve continuous conveyors upon which the feed material is
placed and processed. The 'feed is normally a mixture of
calcine or concentrates, recycled ground sinter, and the re-
quired amount of carbonaceous fuel, each of which is pelletized
and sized before it is fed to the machines and ignited. During
processing the combustion gas and large quantities of dust
are carried away from the sintering machines. Usually 5 to
10 percent of the total feed a.ppea.rs a,s dust in the ga.s that
is discharged.
At horizonta.l-retort distillation plants, processing is a batch-
type operation. The horizontal retorts are small ceramic
-------
-16-
ELECTROLYTIC ZINC PLANT FLOW DIAGRAM
CONCENTRATE UNLOADING
FLASH ROASTER
Steam
SO
WASTE HEAT BOILEI
Wash Waters
_*_
SULFURIC ACID
PLANTS
1
Sulfuric Acid to Market
Spent Electrolyte
CONTINUOUS LEACH |
Wash Waters to Leach
T
Wash Waters
BURT FILTERS
CuSO4
As?O
RESIDUE TREATMENT
f
Zinc Plant Residue
to Smelter
Zinc Dust
CONTINUOUS PURIFICATION
FILTRATION
Residues^
ELECTROLYTE
COOLING TOWERi
ELECTROLYSIS
Spent Electrolyte to Leach
CADMIUM
PLANT
Elect fo.ly tic
Cadmium to
Ma rket
Copper Residue
to Copper Smelter
• a i
[CATHODE STRIPPING!
Figure II
-------
-17-
cylinders that are mounted horizont.aj.ly in furnaces that
hold several rows of retorts mounted one above the other.
They are heated by passing hot combustion ga.ses through
the spaces around the outside. The charge of zinc-bearing
material and reduction fuel is contained inside and is sub-
jected to prolonged exposure to the reducing atmosphere at
a temperature of about 2, 000 F.
When smelting is ready to begin, the retorts are charged
and condensers are placed over the ends to condense the
majority of the zinc vapor emerging. The mouths of the
condensers are stuffed with charge or other available high-
zinc material, almost completely sealing the outlet. Hea.vy
firing is started and gas is allowed to escape through one
small hole in the stuffing. About 6 hours after starting, the
first zinc begins to come off the charge and the condensers
must perform their functions. The formation of blue powder
takes place if the temperature is low enough to prevent the
escape of uncondensed zinc. If it is high enough to minimize
blue powder formation, then there is appreciable loss of
vapor. In foreign plants this fact has led to the use of con-
densing devices called prolongs, which are designed to re-
cover the escaping vapor as blue powder. Prolongs increase
-------
-18-
zinc recovery about 2 or 3 percent, bur in the United States
the cost of using them is usually considered to be greater
than the value of the extra recovery.
The vertical-retort process is a continuous method for pro-
ducing high-purity zinc by pyrometa.llurgica.l. means. High
boiling-point impurities such as lead and low boiling-point
impurities such as cadmium can be separated from relatively
impure zinc.
The vertical-retort furnaces consist, of 3 ma.jor sections:
the charge column, the reflux: section, and the combustion-
hearing chamber. The charge, which consists of hot bri-
quettes, enters the charge column through a door located
near the top. During charging, effluent from the retort is
exhausted directly to the atmosphere through a. short stack
located on t.op of each retort. The charge moves down through
r.he combustion or hea.ting zone of the column and heat pro-
duced in the combustion c.ha.mber is transferred through the
refra.ctory walls of the column, to the charge. Gases leaving
the retort section of the heating zone contain zinc va.por, car-
bon monoxide, and pa.rticulates driven from the briquettes.
The gases pa.ss our. the top of the column to a. condenser where
-------
-19-
th e zinc is condensed from the gas stream. Next, the gas
is scrubbed and recycled to the combustion zone.
At all zinc smelters visited during this study, bag filters
and/or electrostatic precipitators were employed as the
principal dust collection devices; however, cyclone collect-
ors and scrubbers were also used at some locations. At all
plants there were some emission sources that were uncon-
trolled. There wa.s virtually no control in connection with
concentrate unloading, handling, and storage.
Very few operators were found who actually knew the parti-
cle size of the zinc emissions. The few reports obtained
showed the particle size as ranging from less than 0.5 to
100 microns. At: one horizontal -retort plant, the retort
fumes were reported to be as follows: 34 percent less than
/
2. 5 microns; 35 percent between 2. 5 a.nd 5. 0 microns; and
.31 percent larger ths,n 5 microns. The emissions are com-
posed of zinc ox.ide and sulfur compJex.es.
Emissions from Metallurgical Processing During 1969
zinc emissions to the atmosphere resulting from metallurgi-
cal processing of zinc-bea.ring ores and concentrates totaled
i
50, 000 tons. This estima.te is based on emission and material
-------
-20-
bala.nce data obtained from processing companies during
field trips to primary slab zinc plants.
Zinc emission fa.ctors based on the data obtained are as
follows:
Type of Plant
Electrolytic zinc plant
Vertical-retort zinc plant
Horizontal-retort zinc plant
Pounds Zn Emissions
per Ton Zn Produced
60
80
170
-------
-21-
SECONDARY ZINC PRODUCTION
In the United States the production of secondary zinc is im-
portant. During the recent years it has accounted for more
than 20 percent of the total supply. It is produced in both
alloyed and unalloyed forms from old and new scrap, as
shown in Table V.
Zinc scrap is processed in several different ways. Some is
redistilled at primary and secondary zinc plants. Some is
vaporized in furnaces and then converted to zinc oxide in
suitable combustion chambers. Some is processed in re-
torts and condensed to slab zinc or zinc dust. However,
about 50 percent of the zinc in scrap is in the brass that is
remelted by brass and bronze producers for the production
of more brass.
When dealing with scrap metal, various problems are in-
volved that are different than those encountered when deal-
irg with ores and concentrates. There are many types of
scrap and some are relatively pure whereas others are al-
loys containing varying amounts of zinc. Even though scrap
metal may be pure zinc, it is often intimately associated
with non-metallic materials such as chemicals, dirt, grease,
-------
-22-
TABLE V
ZINC RECOVERED FROM SCRAP PROCESSED IN THE
UNITED STATES DURING 1969 V
(Short Tons)
Kind of Scrap
New Scrap:
Zinc-base
Copper-base
Other
TOTAL
Old Scrap:
Zinc-base
Copper-base
Other
TOTAL
134,668
156,381
3,715
294/764
40,284
37,975
3, 368
81,627
Form of Recovery
As metal
In zinc-base alloys
In brass and bronze
In other alloys
In chemical products
TOTAL
107,557
19,980
196,244
7,312
45,298
376,391
1- Minerals Yearbook; Bureau of Mines; 1969.
-------
-23-
insulation, moisture, oil, paint, plastics, rubber, and
many others.
Raw material preparation is an important operation in scrap
metal processing. The dealers must first identify and sort
the scrap, then it must be further inspected and sorted when
it is received at smelters, brass mills, and other process-
ing facilities. After sorting, some of the material is pre-
treated mechanically and some requires a preliminary furn-
ace treatment. Such treating prior to smelting is usually at
a. rather low temperature and various types of furnaces may
be employed. A muffle furnace or kiln may be used to drive
off moisture, oil, and other organic impurities. After the
raw material has been prepared the remaining procedures
for melting and refining are principally material handling
and pyrometallurgical operations utilizing cupolas, crucibles,
reverberatories, and other types of furnaces. There is no
basic difference in the melting and refining actions in these
furnaces, but there are differences in the alloys processed,
the furnace capacities, the condition of charge materials,
a.nd the methods for heating.
From the standpoint of zinc emissions to the atmosphere, the
-------
-24.
remelting of bronze does not hold great interest. Copper
and tin are the principal elements in a true bronze and the
quantity of zinc is low, usually less than 5 percent. Also,
the boiling points of copper and tin are above 4, 000 F while
the normal pouring tempera.ture is in the range of 2, 000 to
2,200 F. The remelting of brasses containing 15 to 40 per-
cent zinc, however, presents a different situation. The pour-
ing operations are carried out at temperatures that are near
the boiling points (about 2, 200 F) and there is some vapori-
zation.
Zinc is melted in crucible3 pot, kettle, reverberatory, or
electric-induction furna.ces and is reclaimed from higher
melting point metals in sweat furnaces. Secondary refining
of zinc is carried out in retort furnaces. This reduction pro-
cess is used to reclaim zinc from the dross formed in zinc-
melting operations, the zinc oxide collected by air pollution
control systems, and the contaminated zinc oxide from zinc
oxide plants.
The emissions of zinc and other pollutants vary in composi-
U'.-n and concentration during the operating cycle of the re-
tort.s. At, first, there are few, if any, zinc emissions. The
-------
-25-
charge is moist and steam is emitted as the retorts are
heated. After several hours when zinc begins to form, both
carbon monoxide and zinc vapors are discharged. During
the heating cycle, zinc is poured from the condensers about
3 times and each time the emission of zinc vapors increases.
At the end of the cycle, zinc fumes and dust are discharged
to the atmosphere as the spent charge is removed. As the
zinc vapors mix with air, they oxidize and form a dense white
cloud of zinc oxide fumes.
Emissions from Secondary Zinc Production - There are
large variations in the concentrations of zinc fumes that are
discharged to the atmosphere during the production of secon-
dary zinc. Emissions from brass melting operations may
vary from less than 0. 5 percent to 6 percent of more of the
total metal charge /, and 2 to 1 5 percent of the zinc con-
tent /. Uncontrolled particulate emissions have been
reported to range from 1 to 70 pounds per ton of
1- St. John, H. M. ; "Melting Practice in the Brass Foun-
dry"; Foundry; 83_; Nov., 1955.
2.. Allen, G. L,. : Viets, F. H. ; McCabe, L. C. : "Control
of Metallurgical and Mineral Dusts and Fumes in Los
Angeles County, California": Bureau of Mines; Info.
Circ. 7627; Apr. , 1952.
-------
-.26-
charge _/ /, whereas controlled emissions range from
2
0. 1 to 1 pound per ton of charge /.
Chemical analyses of dust collected in a brass and bronze
smelter ba.ghouse show the zinc content varies from 45 to
77 percent /. Another report on a series of tests in Los
Angeles County indicated the zinc oxide content of tume from
representative red and yellow brass furnaces averaged 59
percent /.
Data obtained from industry during this study indicates that
zinc emissions to the atmosphere during the production of
seconda.ry zinc vary from 0. 01 to 124 pounds per ton of prod-
uct, averaging 20 pounds per ton. During 1969 zinc emissions
to the atmosphere totaled 3, 800 tons.
1 "Air Pollutant. Emission Factors";. Environmental Pro-
tection Agency' Preliminary Document: Apr. , 1971.
2- Air Pollution Engineering Manual; Public Health Service
Publication No. 999-AP-40; 1967.
3- Spendlove, Max J. : "Methods for Producing Secondary
Copper"; Bureau of Mines: Info. Circ. 8002; 1961.
4- Allen, G. L. ;, Viets, F. H. : McCabe, L. C. ; "Control
of Metallurgical and Mineral Dusts and Fumes in Los
Angeles County, California"; Bureau of Mines; Info.
Circ. 7627: Apr. , .1952.
-------
-27-
END PRODUCT USES OF ZINC
In the United States during 1969 about 29 percent of the pri-
mary and secondary zinc was used in the commercially pure
form, principally for galvanizing sheet, strip, tubes, .pipes,
fencing, structural shapes, and other steel articles. Approx-
imately 55 percent was consumed as an alloying element in
the production of zinc-base and copper-base alloys.
The largest, application of zinc was in zinc-base die-casting
a.lloys used extensively by the automotive industry. During
1969 the zinc consumed in the manufacture of automobiles
was approximately 35 percent of the zinc produced.
-------
Zinc-Base Alloys
Zinc-base die castings are now used extensively in several
industries since the great advancements made by the die-
casting industry itself during the last 30 years. Products
with good stability.- easy ma chinability, attractive appear-
ance, and reasonable cost are now easily formed. The auto-
mobile industry uses 55 to 60 percent of the die-casting pro-
duction in. such items as ca rburetors; fuel pumps, door hand-
les, radiator grills, windshield-wiper motors, and other in-
terior and exterior hardware. The home appliance producers
also make good use of zinc-base die castings in sewing ma-
chines, ironers, wa.shing ma.chines, radio and television sets,
and kitchen, and food-mixing equipment. Additionally, com-
mercial machines and tools, builders' hardware, office equip-
ment and business ma.ch.ines, a.nd optical and photographic
equipment use a large variety of these castings.
There are only a few zinc -base alloys in use for die casting.
Aluminum is the major alloying constituent used in quantities
•varying from 3. 5 to 4. 3 percent. A zinc -a.luminum alloy im-
pa.rts increased strength and slows the atta.c.k of the alloy on
iron and steel, parts. The amount of copper tha.t may be used
in a. zi.nc.-ba.se alloy varies some, but the usual qua.ntity is
-------
-29-
0. 25 to 0. 75 percent for increasing tensile strength and hard-
ness. Magnesium reduces subsurface corrosion and counter-
acts harmful effects of small impurities. It is usually not
added in amounts greater than 0. 05 percent.
Virgin metals are always preferred when manufacturing the
alloys for die casting. The procedure itself is usually ac-
complished in a pot or reverberatory furnace. The alloy is
then cast into bars or pigs that fit the melting pots at the die-
casting machine.
The actual die-casting machinery is generally well automated
and is often a "hot chamber" machine because it is simpler
and faster to operate. The zinc-base alloys are first melted
in pots ranging in size from 2, 000 to 8, 000 pounds. The tem-
perature of this metal in the pot should not exceed 800 F, and
a good range is. 300 to 400 F. The molten metal flows from
the pots, filling an adjacent cylinder. A plunger is forced
down pushing the metal from the cylinder into the die for the
cast. The dies themselves are ordinarily made of high qual-
ity steel and .filled at temperatures up to 950 F. The opera-
tion of this machine usually requires an operator to open and
close the dies and remove castings.
-------
...30-
At most plants the scrap genera.ted during die-casting opera-
tions is remelted, cleaned, a.nd reused. From the standpoint
of air pollution, these reclaiming operations usually account
for most of the emissions to the atmosphere, Normally in-
duced draft ventilation systems are used, but there is no dust
or fume collection equipment.
Slush ca.stings are utilized only in a very small way as com-
pared with die castings. Their primary purpose is in the pro-
duction of hollow ca.stings and they a re mainly employed in
the lighting fixture and novelty field. To make these castings,
a. metal shell is frozen on the inner surfa.ce of a split mold.
The mold is inverted quickly so the molten metal flows away
a.nd the thin shell casting remains. The alloys used in these
castings must have a fairly low freezing temperature and
solidifica.t-.ion over a range of tempe ra tu res. These alloys
usually consist of 94 or 95 percent zinc, and the remainder
is aluminum or aluminum a.nd copper.
During this study the information obtained from die-casting
compa.nies indicates thai zinc emissions to the atmosphere
a eraged about 10 pounds per ton of zinc, processed, even
<.hough the range reported was from less than 10 to as much
-------
-31-
as 60 pounds per ton. Based on the average of 10 pounds
per ton, the atmospheric emissions in the United States in
1969 totaled 3,000 tons.
-------
-32-
Zinc Coatings
Galvanizing - The hot-dip process is the most important
galvanizing method used for coating clean iron and steel sur-
faces with a thin layer of zinc. It is adaptable to the coating
of nea.rly all types of articles and-the basic steps in the pro-
cess are:
1 - Preparation of the metal surface by degreasing,
rinsing, pickling, and rerinsing.
2 - Prefluxing by immersion of the metal in a tank
of p.reflux.
3 - Galvanizing by immersion in a tank of molten
zinc.
4 - Finishing by shaking or centrifuging, water
quenching, deburring, and inspecting.
The galvanizing industry used 450, 000 tons of slab zinc dur-
ing 1969, which was 33 percent of the total slab consumption.
.About half of the ga.lva,nized sheet produced is used by the
building industry, but another importa.nt application is the
production, of automobile underbody parts. Familiar appli-
cations for galva.nized steel are roofing sheet, guttering, cul-
verts, fencing, pipe, wire, pole-line hardware, nails, pipe
fittings, switch boxes, electrical conduit, tanks, and hot
-------
water heaters. A growing use is for galvanized structural
steel members for such structures as bridges and transmis-
sion towers.
The basic chemical factor in galvanization is that zinc read-
ily combines with iron to form an alloy layer consisting of
several layers, each increasing in zinc content from the steel
to the surface. The galvanizing kettle is made of steel and
either riveted or welded. The shape and size of the kettle
are generally dependent on the work to be galvanized in them.
Most kettles are side-fired and have a layer of lead on the
bottom to reduce the reaction between the zinc bath and the
iron of the kettle, and to improve heat distribution. When
continuous operation is used, the average pot capacity is a-
bout 20 tons of zinc per ton of material galvanized per hour.
Prior to the actual, zinc -coating bath, the steel to be coated
may be immersed in a hrdrofluoric acid solution to dissolve
gra.ins of sand, a.nd then a cleaning or pickling solution of
sul.furic or hydrochloric acid. Superficial oxide may also be
removed by passing the steel through a solution of 5 to 20
percent zinc ammonium chloride. Continuous sheet is given
this zinc ammonium chloride bath, and then dried at. about
350 to 550 F to a tacky state.
-------
-34-
After these preliminary treatments, the steel passes into
the zinc bath ra.nging from 840 to 860 F. As wire is coated,
it must be held beneath the surface with sinker bars. Pipe
is given a flux wash and then rolled into the galvanizing ket-
tle. Small parts are generally handled in baskets and larger
structural shapes are moved by crane. Continuous sheet
passes into the molten zinc bath at about 840 F, and remains
from 3 to 20 seconds for the desired coating.
Following the hot zinc bath, materials exit by different meth-
ods.. Wire passes through asbestos pads or a charcoal bed,
is cooled by water, and wound on a reel. Sheet leaves through
exit rolls, cools, and then goes to leveling and finishing op-
erations. Pipe is removed so that maximum draina.ge occurs
from the inside, and then a blast of steam is used to remove
excess zinc. Small parts are placed in a centrifuge in bas-
kets to rid the excess zinc.
Final treatments may include blowing with a fume from burn-
ing sulfur or annealing immedia.tely after the bath in a furn-
ace as high as 1,200 F. For improved corrosion resistance
and paint adhesion, chromate or phosphate treatments may
be used. These subsequent treatments and variations in
-------
-35-
ope.ra.ting conditions result in changes in the coating produced.
Zinc losses from dressing and skimming during galvanizing
depend a great deal on the product. A loss occurs on pole-
line hardware castings, which is usually greater than 25 per-
cent of the zinc sl.a.bs melted. It may be as high as 50 percent
if galvanizing ba.th time and temperature are not ca.refully ob-
served. Sheet is generally the most economical with respect
to losses, which usually amount to about 10 percent.
During hot-dip galvanizing operations most of the atmospheric
poMuta.nts are discharged when fresh flux is added, or when
the flux cover is distrubed as it is each time an article is im-
mersed into the zinc ba.th. Ammonium chloride is the princi-
pal pollutant; however, there are significant quantities of
zinc, zinc oxide, and zinc chloride in the fumes, as shown
in Table VI.
Processing operations at '.he galvanizing plants that were
visited were similar, but the p.ra.ctices followed varied some-
what. In some in.sta.nces the flux cover was agitated much
more than in others, and no doubt emissions were substan-
tially greater. There were no records of emissions and
only 2 companies responded with emission estimates.
-------
...36-
TABLE VI
CHEMICAL ANALYSIS OF THE FUMES COLLECTED BY
A BAGHOUSE AND BY AN ELECTRIC PRECIPITATOR
FROM ZINC-GALVANIZING KETTLES
Component
NH4C1
ZnO
ZnC.l2
Z.n.
NH3
Oil
H2O
C
Fumes Collected
in a Baghouse
(Job Shop Kettle)
wt. %
68. 0
15. 8
3.6
4. 9
1. 0
1.4
2. 5
2.8
Fumes Collected
in a Precipitator
(Chain Link Galvanizing)
wt. %
23.5
6.5
15.2
-•-
3.0
41.4
1. 2
... _.
Not Identified
9.2
"Air Pollution Engineering Ma.nual "; Public Health Service
Public.ar.ion No. 999-AP-40; p. 405 1967.
-------
-37-
Based on observations a.nd information obtained during this
study, zinc emissions to the atmosphere due to galvanizing
operations during 1969 are estimated at 4 pounds per ton of
zinc processed, or a total of 950 tons.
-------
-38-
Shera rdizin.g - Another procedure for coa.ting steel with
zinc is called sherardizin.g. It has advantages over hot-
dipped coatings for certain steel articles. There is only a
slight dimensional change of an article during sherardizing
permitting treatment: of small pa.rts such as nuts, bolts,
wa.shers, a.nd small ca.sf.ings. Also3 a sherardized coating
is resistant to cracking, splitting, and flaking when the final
article musi be bent or worked.
In sherardizingj articles a.re placed in a metal drum and
exceedingly fine particle-size zinc dust is added. The zinc
dust is usually a small por'ion of new dust which has been
added to used dust. The zinc content is between 80 and 92
percent, with the remainder being zinc oxide and other im-
pijri'ies. The drum is then, sealed tightly to minimize zinc
oxidation and prevent the escape of zinc vapor. Gas, oi]3
or electricity heats the drum as it slowly rotates, producing
a uniform coating. The temperature ranges from 660 to 700
F a.nd the coa.ting thickress is determined by varying the
treatment time from 3 1o .12 hours. Sherardizing continues
e . en during cooling, which is done slowly to prevent loss by
exposing hot zinc dust to the atmosphere. Cleari3 metal sur-
face^ are impor'.ant therefore, a pickling operation followed
-------
-39-
by cold and then hot water rinses is usually employed. If
conditions are kept constant a uniform coating with a con-
trolled thickness is produced.
Emissions to the atmosphere due to sherardizing .are con-
sidered by the Contractor as negligible.
-------
-40...
Electrolytic Deposition - Zinc can be deposited on sheet3
wire, a.nd all'types of hardware electrolytically for corro-
sion protection. Zinc can be plated from a solution only be-
cause of its high hydrogen ove.rvoltage and even then some
substrates, such as ca.st iron, must be struck with tin or
cadmium prior to zinc plating.
The zinc cyanide bath is used for general plating. However,
zinc chloride, su.lfate, a.nd fluoborate baths a.re used in strip
and wire plating because they are capable of higher plating
speeds. A new pyrophosphate bath has also been introduced
which eliminates the problem of cya.nide disposal. Chromate
posf;-treatment solutions are used for better appea.ra.nce and
performance.
Emissions to the atmosphere due to electrolytic deposition
of zinc, a.re considered by the Contractor as negligible.
-------
-41-
Brass and Bronze
Brass is a copper alloy in which zinc is the principal alloy-
ing element, usually added in amounts up to 40 percent. The
most used brasses of commerce are cartridge brass, contain-
ing 30 percent zinc, and yellow brass containing about 35 per-
cent. Bronze is also a copper alloy that contains zinc but
normally the zinc content is not more than 5 percent.
About half of the zinc contained in the brass and bronze pro-
duced during 1969 was originally slab zinc, while the other
half was recovered from scrap brass and bronze as described
in the secondary zinc section of this report.
During the processing of brass 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 meta] is poured and
cast at temperatures ranging from 1,200 to 2,400 F, the
actual temperature depending upon the a]Joy. The molds
used to form slabs, cakes, and biJlets 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 drawn into wire. Final
-------
-42-
finishing operations include flattening, straightening, slitting,
and cutting.
The emissions of zinc and other polluta.nts vary in composi-
tion and concentration with the type of furnace, the alloy,
and the foundry practice as indicated by the data in Table VII.
During 1969 the slab zinc used in brass products totaled
179,469 tons /, while the zinc emissions estimated by in-
dustry averaged 2 pounds per ton of zinc processed. Zinc
emissions to the atmosphere for the year totaled 180 tons.
1 - Minerals Yearbook; Bureau of Mines; 1969.
-------
-43-
TABLE VII
BRASS-MELTING FURNACE
AND BAGHOUSE COLLECTOR DATA
Case
B
Furnace Data
Type of furnace
Crucible
Crucible
Low-frequency
induction
Fuel used
Metal melted
Composition of metal
melted, %
Copper
Zinc
Tin
Lead
Otter
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
Type of bagh.ouse
Filter material
Filter area, ft2
Filter velocity, fpm
Inlet fume emission
rate, Ib/hr
Outlet fume emission
9,500
Sectional
tubular
Orion
3,836
2.47
2.55
9,700
Sectional
tubular
Orion
3, 836
2.53
1.08
1, 140
Sectional
tubular
Orion
400
2. 85
2.2*
rate, Ib/hr
Collection efficiency, %
0. 16
93.7
0.04
96.2
0. 086
96. 0
'Includes pouring and charging operations
"Air Pollution Engineering Manual"; Public. Health Service
Publication No. 999-AP-40; p. 274; 1967.
-------
44.
Zinc Oxide
Zinc Oxide Production - Zinc oxide is the principal zinc
compound used by industry and 3 types are produced com-
mercially in the United States, one being made by chemical
processes and the other 2 utilizing pyrometal.l.urgica.1 proced-
ures. The French process oxide, generally referred to as
the indirect type, is characterized by its brightness, extreme
whiteness, and a high degree of purity. The American pro-
cess oxide, the direct type, is less bright and contains more
impurities. . The chemical processes produce secondary zinc
oxides which are very pure, but are coa.rse and not as bright
as either of the other 2 types.
When employing either of the pyrometallu rgical procedures
to produce zinc oxide, the ores and concentrates, or the scrap,
must first be processed to produce zinc vapor. Then at that
stage the vapor may be either condensed to produce slab zinc
o.r oxidized to make American process zinc oxide. If the
French process oxide is the desired product, the va.po.r is con-
densed to form metallic zinc, after which the metal is vapor-
ized and oxidized to form the product.
Zinc oxide is produced at primary and seconda.ry smelters.
-------
-45-
Information obtained from both types of plants indicates that
zinc emissions to the atmosphere during the production of
zinc oxide ranges from 20 to 170 pounds of zinc per ton. of
product. Based on a weighted average of 60 pounds per ton,
the emissions during 1969 totaled 8, 100 tons.
The manufacture and use of consumer products containing
zinc oxide is also very important from the standpoint of zinc
emissions to the atmosphere. During 1969 more than
220; 000 tons were used in the manufacture of abrasives, ad-
hesives, agricultural products, catalysts, ceramics, cos-
metics, dental cements, feed additives, floor coverings,
glue, insect repellents, lubricants, paints, pharmaceuticals,
photocopying supplies, pla.stics, printing ink, pyrotechnics,
rubber products, soaps, textiles, vita.mins, and other items
including various zinc compounds.
-------
-46-
Rubber - The largest use of zinc oxide at the present time
is in rubber products, principally as an activator in the vul-
canization process. There are other properties, however,
that also contribute to its popularity as a compounding in-
gredient. It helps to protect rubber by its opaqueness to
ultraviolet light and by its high thermal conductivity.
During the manufacturing process the additives to be com-
pounded into the rubber must be homogeneously dispersed
throughout the blend. Rubber mills and Banbury mixers are
the principal items of equipment employed for this purpose
and it is at these locations where some zinc oxide emissions
occur. The remaining steps include several forming and
shaping procedures prior to the vulcanization process in
which the plastic raw material is converted to an elastic
state. The significant emissions of zinc that occur during
the production and use of rubber products are those that are
due to the wear of vehicle tires.
The usual dosage of zinc oxide is in the range of 60 to 100
pounds per ton of rubber and the average quantity per vehicle
tire has been reported to be about 0. 5 pound (Zn content. -
0.4 pound). During 1969 motor travel in the United States
-------
-47.
was about 1.05 x 10 miles including passenger cars,
motorcycles, buses, and trucks. On the average, the life
of a tire is 20, 000 miles and when replaced, 20 percent of
the rubber is worn away /. Calculated on the basis of 4
tires per vehicle, the zinc emissions due to the wear of
tires during 1969 totaled 8,400 tons.
- P.riva.te communication.
-------
-48-
Photocopying - The second largest use of zinc oxide is in
photocopying where its photoconductive and electrostatic
properties are used to advantage. Conventional printing
paper is coated with zinc oxide paint which is then made
light sensitive by subjecting it to a negative corona discharge.
The copy is made by placing the material to be reproduced
between a light source and the charged paper. Where the
light passes through to the zinc oxide paper, the electrosta.tic
cba.rge is dissipated. The image is readily developed by ap-
plying a pigmented resin powder that, adheres only to the areas
where the electrostatic cha.rge has not. been removed. The
ima.ge is finally fixed to the paper by heating.
During 1966 through 1969 an average of J 5, 000 tons of zinc
per year were used in photocopying, an.d the emissions re-
sulting from that use were principally those due to the burn-
ing of discarded copies. Ba.sed on the assumption tha.t: 10
percent of the copies were discarded and burned, zinc emis-
sions to the atmosphere during 1969 were approximately
1, 500 tons.
-------
Paints - Another large use of zinc oxide is in paints for ex-
terior wood surfaces. In this application it has a number of
desirable effects. It aids in mixing and grinding, improves
drying and hardening of the paint film, reduces paint discolor -
a.tion, improves mildew resistance and self-cleaning, and re-
duces chalking. Emulsion-type la.tex pa.int coatings for use
on cement and masonry surfaces also require the use of zinc
oxide for the same purpose as oil-base paints, with the addi-
tional benefit of helping to reduce can corrosion.
At the paint factory the zinc oxide is received in paper sacks
and emptied into vats containing a liquid. There is a small
amount of dusting as the sacks a.re emptied, and at most of
the locations visited during this study there were ventilation
sysrems. At some factories there were exha.ust systems
with hoods over the vats and a fan discharging to the atmos-
phere. At other pla.nts the vats were entire.ly enclosed and
the exhaust was through a bag filter. Ar. one plant the men
handling the sacks wore respiratory equipment. There were
no hoods over the vats, but the entire building was ventilated.
Usually there was some dust on the floor around the vats,
and traces of zinc oxide remained in the empty bags which
were either burned or discarded with the other trash.
-------
-50-
There were no emission records available at any of the
paint factories and there was no basis for an accurate esti-
mate. Based on observations it is reasonable, however, to
assume that the atmospheric emissions of zinc oxide do not.
exceed one pound per ton of zinc oxide processed. The quan-
tity used in paint in 19&9 was 25, 170 tons, and emissions are
estimated at 10 tons (Zn content).
-------
Other - The miscellaneous uses of zinc oxide are numerous,
collectively accounting for about 23 percent of the total con-
sumption in 1969. In ceramics and glasses including glazes,
enamels, and frits it is an essential ingredient. In glasses
it reduces the melting time, lowers viscosity, and raises
chemical and mechanical resista.nce. Up to 15 percent zinc
oxide may be used for heat-resisting glass, technical glass,
optical glass, selenium ruby glass, and yellow nickel glass.
For special purposes the zinc oxide content is even higher,
sometimes over 50 percent. In glazes it contributes to fusi-
bility, increases resistance to thermal and mechanical shock,
prevents crazing, improves luster, and enhances opacity.
Another application of zinc oxide is in porcelain enamels
for sheet iron and vitreous enamels for cast iron. In these
applications it contributes to electrical resistivity. These
enamels are used extensively on refrigerators, ranges,
washers, sinks, and toilet fixtures;
The principal sources of zinc emissions during the making
of glass, glazes, and ena.mels are the initial dry mixing
operations and the melting furnaces.
Miscellaneous uses of zinc oxide are relatively minor, none
-------
accounting for more than 0. 3 percent of the total use of
zinc. Since emissions resulting from these uses cannot, be
calculated accurately, all factors have been considered and
a conservative figure of 1, 000 tons has been estimated by the
Contractor as the zinc emissions to the atmosphere during
1969 due to the use of zinc oxide in ceramics, gla.ss, feed ad-
ditives, floor coverings, soaps, and other products.
-------
Rolled Zinc
Rolled zinc is generally produced in all the usual forms of
sheet, strip, pla.te, rod, and wire. For this purpose it is
preferable to use high-grade zinc adding alloying met:als
such as copper, magnesium, manganese, chromium, and
titanium in controlled a.mounts. A zinc content of 99.8 per-
cent or more gives good drawing characteristics, and the
alloy additions provide a material with a wide range of tem-
pers and strengths. Rolled zinc may be buffed, painted,
plated, la.cquered, chemically colored, and enameled to pro-
vide a wide variety of finishes. Among its uses are photo-
engraving, lithography, dry cells, weather stripping, and
many building applications.
The zinc and its alloying elements are usually melted in a
reverberatory-type furnace, although induction furnaces may
be used when careful product control is necessary. The
furnace temperature for melting is about 850 t,o 950 F. After
the melting operation, the zinc is cast into molds for rolling
slabs. Prior to rolling operations, these slabs a.re then
heated again to a temperature range of 300 to 500 F depending
on the desired product. The rate of reduction during rolling
is determined by the analysis of the metal, the type of
-------
-54-
equipment, and the desired finish.
The manufacturing of photoengraving zinc follows approxi-
mately the same procedures as used in ordinary rolled zinc.
In making these plates, virgin zinc (spelter) is purchased
from a refinery and a.n electric induction furnace is used to
remelt the spelter. The molds used are equipped to give con-
trolleid cooling for as perfect a slab as possible. Finally,
molds are placed in a. holding oven before rough rolling, cold
rolling, and trimming. After the rolling the zinc pla.tes are
degreased, painted on the back with a special acid-, alkali-
resista.nt material, and baked. Grinding, washing, polishing,
inspection, and packing are the final steps. It might be noted
that there is a large percentage of reject material throughout
the operations due to the necessity for surface perfection on
the plates, and this furnishes some portion of secondary zinc.
Rolled zinc sheets are used as press plates in offset lithog-
raphy. These plates must have the tensile strength to allow
clamping without distorting the plate cylinder, and toughness
to resist fatigue and breakage. Zinc plates may have a plain
or grained surface. The gra.ined surface is presently most
used. This is produced in a graining machine with steel
-------
-55-
balls, an abrasive, and water. After graining, the plates
are washed thoroughly and dried with a minimum of heat to
prevent recrystallization of the zinc plate. The grained sur-
face of a plate provides a tooth for the printing image and ink,
and enables the plate to carry the proper amount of water in
the non-printing areas. In many cases, after the completion
/•
of the press run, the zinc press plates are removed, cleaned,
flattened, and regrained for future use.
Strip-rolled zinc is also used in manufacturing dry-cell
batteries. It is soldered into a cylindrical shell, although
currently the cans for standard flashlight-size batteries and
smaller sizes are most often drawn zinc. Zinc chloride is
also used in the paste which fills the battery can. Another
dry battery, known as the flat-cell type, uses a flat piece of
strip-rolled zinc to provide electrical contact between the
combined cells within the battery.
A high-grade zinc with varying alloys provides a material
with a wide range of temper and.strength characteristics, for
building applications. Strip with lower alloy content is use-
ful for flashings, valleys, corner bead, and other architect-
ural uses. Higher alloys produce strip used as weather
-------
-50-
strip, terrazzo strip, wall ties, moldings, and downspouts.
From the sta.ndpoint of air pollution, the production and use
of rolled zinc does not appear, to be a problem of any conse-
quence. Manufacturers have advised that zinc emissions are
negligible and air pollution control equipment is not required.
-------
-57-
Zinc Sulfate
During 1969 about 30 percent of the zinc sulfate was used
for agricultural purposes and 30 percent in the manufacture
of viscose rayon fiber. The remainder was consumed in
many minor process applications including clarification of
glue, paint and varnish processing, electrogalvanizing solu-
tions, froth flotation of minerals, and wood preservation.
Zinc sulfate is usually prepared by leaching roasted zinc ore
concentrates with sulfuric acid solution and filtering out the
residue. After removal of metal impurities, the solution may
be evaporated and dryed in a kiln, a spray dryer, or other
similar equipment.
Reports from 24 manufacturers that prepare or use zinc sul-
fa.te indicate that atmospheric emissions average not more
than 0. 5 pound of zinc per ton of zinc sulfate processed. .Dur-
ing 1969 the zinc sulfate produced was 64,274 tons _/ (Zn
content - 22, 000 tons), and zinc emissions to the atmosphere
totaled about 30 tons.
1- Minerals Yearbook; Bureau of Mines; 1969.
-------
-DO-
Miscellaneous
The miscellaneous uses of zinc which amounted to 94, 000
tons during 1969 include the zinc dust and slab zinc consum-
ed in the production of several light metal alloys, the de-
silverizing of lead, the manufacture of wet batteries, the
production of bronze powder, and other minor uses not in-
cluded in other sections of this report.
In the desilverizing of lead, the lead bullion gives up its sil-
ver content to zinc. In general the 2 processes used both
(
include the "stirring-in" of zinc, cooling, skimming silver-
i
zinc crusts, and distillation of crusts. During 1969 the slab
zinc consumed for this purpose was 3,957 tons /. None
of the smelting companies contacted during this study pro-
t
vided estimates of zinc emissions due to desilverizing oper-
ations.
Zinc is used as the anode of various "wet" batteries such as
the Lalande cell, Eveready air-eel], National Carbon air-
cell, and the comparatively new silver-zinc battery. The
manufacturers of these batteries were contacted and without
1- Minerals Yearbook; Bureau of Mines; 1969.
-------
-59-
ex.ception they reported that zinc emissions are negligible
during manufacturing operations.
Zinc is a secondary or minor ingredient in many light metal
alloys, including both the cast and wrought alloys of alumi-
num and magnesium. It is also frequently alloyed with tin
as in aluminum solders, Britannia metal, pewter, and
"Queen's metal". In silver solders the zinc content ranges
from about 5 to 40 percent.
Estimates of zinc emissions to the atmosphere resulting from
miscellaneous uses of zinc have been estimated by the Con-
tractor almost entirely without assistance from industrial
sources. Only 2 manufacturers provided emission estimates.
More than 30 others stated their emissions were negligible;
however, some defined negligible emissions as less than one
percent loss of raw material. It is apparent there are some
losses to the atmosphere.during the desilverizing of lead and
during alloying, as well as in the operations using smaller
quantities of zinc.
During 1969 zinc emissions to the atmosphere due to process-
ing and manufacturing operations are estimated by the Con-
tractor at 100 tons, or approximately 1/10 of one percent of
the zinc consumed for such miscellaneous purposes.
-------
-60-
OTHER SOURCES OF ZINC EMISSIONS
COAL
A search has been conducted and information has been found
regarding the zinc content of coa], ash of coal, and fly ash
emissions from coal fired power plants.
With respect to fly ash, there is a study of emissions from
coal fired power plants which shows the analysis of several
fly ash samples. Six power boilers were tested, each a dif-
ferent type, and each va.lue reported was the average of at
least 2 tests. Two of the boilers were fired with Illinois
coal; 2 burned Pennsylvania coal: one used some coal from
Ohio and some from West Virginia; one burned part Ken-
tucky and part West Virginia coal. The coal burned during
the tests represented only a small portion of the coal mined
in the various regions of the United States.
Zinc concentrations in the fly a.sh samples taken before fly
-4 1
ash collection ranged from 4.2 to 42 x 10 grains per scf /.
1- Cuffe, Stanley T. and Gerstle, Richard W. ; "Emissions
from Coal Fired Power Plants"; Public Health Service
Publication No. 999-AP-,35; 1967.
-------
-4
The average was 18 x 10 grains per scf. Calculations
have been made based on:
(a) 516, 084, 000 tons of bituminous and anthracite
coal consumed in the United States during 1969 /;
(b) 160 scf of flue gas per pound of coal;
_4
(c) 18 x 10 grains per scf zinc concentration;
(d) 85 percent efficiency of control: and
(e) 90 percent application of control.
The zinc emissions calculated iri this manner totaled 5, 000
tons.
516, 084, OOP x 160 x 18 x lQ-4x2,000 fi . (0.85x0.90)1= 5,000
7,000x2,000 L 'J
During the combustion of coal, zinc is discharged with the
ash; part with the bottom ash and part with the fly ash. The
fly ash averages about 65 percent of the total ash.
Many samples of coal have been analyzed and the zinc con-
tent reported as shown in Table VIII. Calculations have been
made based on:
(a) 516, 084, 000 tons of bituminous and anthracite
coal consumed in the United States during 1969 /;
1- Minerals Yearbook; Bureau of Mines; 1969.
-------
(b) 54. 6 ppm average zinc concentration in coal;
(c) fly ash 65 percent of total ash;
(d) 85 percent efficiency of control; and
(e) 90 percent application of control.
The zinc emissions calculated in this manner totaled 4, 310
tons.
516, 084, 000 x 54, 6 x 10"6 x 0. 65 jj - (0. 85 x 0. 90)] = 4, 310
In this report the figure of 4, 310 tons is used as the zinc
emissions to the atmosphere during 1969 due to the combus-
tion of coal.
-------
-63-
TABLE VIII
AVERAGE MINOR ELEMENT CONTENTS OF COAL
FROM VARIOUS REGIONS OF THE UNITED STATES - PPM
Region
Northern Great Plains
Eastern Interior
Appalachian
Western and Southwestern
Ash Content
of Coal - %
13. 4Z
6. 16
6. 11
NR*
Zn Content
of Coal - ppm
59. 0
44.0
7.6
108. 0
Average Zinc Content in Coal 54. 6
•ff
''Not reported
NOTE - The above table based on Geological Survey Bulle-
tins 1117-C and 1117-D; 1966 and 1967.
-------
-64-
OIL
In order to estimate the zinc emissions to the atmosphere
due to the combustion of fuel oil, it was necessary to deter-
mine the zinc content, and the quantity of oil received from
numerous foreign a.nd domestic sources. Some da.ta was ob-
tained from publications, and some from major oil companies.
The zinc content in crude was shown in more than 100 samp-
les of domestic oil; however, the-situation wa.s different
with respect to the metal content of residual oils. The only
reliable information available from published sources was
that regarding nickel and vanadium. The unpublished data
a.vailable consisted of the analyses of 3 samples of imported
residua] oil which was analyzed for the Environmental Pro-
tection Agency, Office of Air Programs, during J971. The
average zinc content of the 3 samples was 4. 17 ppm.
The residual oil used in the United Si;ar,es during 1969, exclu-
sive of use in vessels, was 639 million barrels. This oil
containing zinc at 4. 17 ppm (average) was used-by industrials,
electric utility companies, railroads, oil companies, and the
military, as well, as for heating (Table IX).
-------
-b5-
TABLE IX
RESIDUAL FUEL OIL DATA
Residual Fuel Oil Burned - 1969 (bbls) 6.39,048,000
Pounds per Barrel 340
Zinc Content of Oil (ppm) 4. 17
Based on the data in Table IX, the zinc emissions to the
atmosphere due to the combustion of residual oil totaled
450 tons during 1969.
Due to the scarcity of data on zinc and other trace metals in
oil, the emissions may be considerably more than estimated.
The burning of fuel oil could be a major localized source of
zinc emissions.
-------
-66-
IRON AND STEEL
Steel mills are important sources of zinc emissions to the
atmosphere. Zinc in the iron ore is discharged to the at-
mosphere from the blast furnace as the ore is reduced to
pig iron and zinc in the scrap is discharged from open-hearth,,
basic oxygen, and electric furnaces as pig iron and scrap are
converted to steel.
Blast Furnaces - As the gas leaves the blast furnace, it
contains large quantities of particulates averaging about 150
pounds per ton of pig iron /; however, it is subsequently
cleaned and used as fuel. The gas cleaning is accomplished
in 2 or 3 stages, and the annual overall efficiency is an esti-
mated 97 percent.
During 1969, the pig iron produced in the United States
2
totaled 95, 472, 000 tons _/. The estimated zinc content of
the particulate from blast furnaces wa.s 0.5 percent /. Zinc
emissions! to the atmosphere from blast furnaces totaled
1, 070 tons.
1- "Air Pollutant Emission Factors"; Environmental Pro-
tection Agency; Preliminary Document; Apr., 1971.
2- Minerals Yearbook; Bureau of Mines; 1969.
3- Varga, J. Jr. , et al; "A Systems Analysis Study of the
Integrated Iron and Steel Industry"; Battelle Memorial
Institute; Columbus, Ohio; May, 1969.
-------
-67-
Open-Hearth Furnaces - The overall operating cycle of the
open-hearth furnace is about 10 hours. Even though fumes
are discharged continuously at varying rates, average emis-
sion factors have been established for operation both with and
without oxygen lancing. With oxygen lancing, the factor for
uncontrolled emissions is 21 pounds of particulate per ton of
steel. Without lancing, the factor is 8 pounds per ton. The
degree of emission control is estimated at 40 percent, and
the average emission factor (controlled) for all open-hearth
furnace operations is 10. 2 pounds of particulate per ton of
steel produced _/.
The mean particle size of the dust is generally considered to
be 0. 5 micron / and the average zinc content 12. 5 percent:._/.
During 1969 the steel produced in open-hearth furnaces was
4
60, 894, 000 tons _/, and the zinc emissions to the atmosphere
totaled 39, 000 tons.
1- "Emissions, Effluents and Control Practices"; Environ-
mental Protection Agency; Study in Progress (unpublished).;
1970.
2- Aberlow, E. B. ; "Modification to the Fontana Open-Hearth
Precipitators"; JAPCA; 7_; May, 1^57.
3- "Air Pollution Engineering Manual"; Public Health Service
Publication No. 999%-AP-40; p. 243; 1968.
4- Minerals Yearbook; Bureau of Mines; 1969.
-------
Ba.sic Ox.ygen Furnaces - The operating cycle of the basic
oxygen furnace is normally a.bou.t one hour, and large quan-
tities of gas and participate are discharged to the atmosphere
throughout the operation. The emission fa.cto.r for this type
of furnace has been estimated a.t 46 pounds of pa.rticulate per
ton of steel I, and the degree of emission control a.t 97
percent.
During 1969 the steel produced in basic oxygen furnaces was
60, 236, 000 tons /, and the estimated zinc content of the
particulate emissions 2. 24 percent /. Zinc emissions to
the atmosphere from basic oxygen furnaces totaled 900 tons.
1- "Air Pollutant Emission Factors"; Environmental Pro-
tection Agency; Preliminary Document: Apr. , 1971.
2- Minerals Yearbook; Bureau of Min.es; 1969.
^_^^_^_^_^__«^_^__^__9__ ^
3- Varga, J. Jr. , et al; "A Systems Analysis Study of the
Integrated Iron and Steel Irj.d.ustry"; Battelle Memorial
Institute: Columbus, Ohio; May, 1969.
-------
-69-
Electric Furnaces - Electric arc furnaces are used exten-
sively for the production of alloy steels and the ra.w matei ia.l
used is principally scrap iron. Emissions generated diaing
operation consist of fume and dust emitted throughout the
charging and refining operations. While cha.rging, the top is
open to receive the cold metal, and the exposure of the cold
charge to the high temperature inside the furnace results in
the generation of large quantities of fume.
Particulate emissions from electric arc furnaces ha.ve been
estimated with and without oxygen lancing a.t 11 pounds a.nd 7
pounds per ton of steel, respectively /. The degree of
control is estimated at 78 percent, and the a.verage emission
factor (controlled) at 2.5 pounds of particulate per ton of
steel produced.
During 1969 the steel produced in electric arc furnaces was
20, 132, 000 tons _/. The zinc content: of the particulate is
estimated at 29. 6 percent /, and zinc emissions to the at-
mosphere from electric furnaces totaled 7,400 tons.
1- "Air Pollutant Emission Fa.ctors"; Environmental Pro-
tection Agency: Preliminary Document; Apr., 1971.
2- Minerals Yearbook; Bureau of Mines; 1969.
3- Coulter, R. S. : "Smoke, Dust, Fumes Closely Controlled
in Electric Furnaces"; Sr'on Age; 173; Jan 14, 1954.
-------
-70-
FOUNDRIES
During this study spectrographic analyses of dust samples
from 3 iron foundries have been examined and they show
zinc is present in all samples, the content ranging from 0.2
to 2. 0 percent _/.
The cupola is the most popular method for producing cast
iron. The rate of particulate emissions from gray iron
cupolaB 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.
Based on information obtained from industry, the particulate
emission factor is estimated at 22 pounds per ton of process
weight, including melting and non-melting operations. The.
degree of emission control is approximately 25 percent.
Calculations show that with 1. 1 percent zinc in the particu-
late, the emission factor is 0. 18 pound of zinc per ton of
process weight,
During 1969 the pig iron and scrap used by iron foundries
1- Private communication.
-------
-71-
totaled 18, 594, 000 tons _/; there£ores zinc emissions to
the atmosphere due to the production of cast iron were
1,700 tons.
1- Minerals Yearbook; Bureau of Mines; 1969.
-------
-72-
INCINERATION
A recent report concerning the burning of sewage and sludge
indicates the present burning rate in the United States is a-
bout 2, 000 tons per day /. Based on an average zinc con-
tent of 2,411 pprn /, the atmospheric emissions of zinc due
to the burning of sewage and sludge during 1969 were 1, 750
ton. s.
The burning of refuse and garbage is also a source of zinc
emissions to the atmosphere. It has been estimated and re-
ported that approximately 50 percent: of all the generated
waste in the United States, or about 5 pounds per person per
da.y, is burned by various combustion methods /. Emis-
sion data have also been reported which indicate tha.t incin-
eration, emissions ra.nge from 3 to 28 pounds per ton of refus<
burned, while the zinc content of the ashed material is from
1- Private communication with the Federal Water Pollution
Control Authority.
2- Clark, L. J. and Hill, W. L. ; "Occurrence of Manga-
nese, Copper, Zinc, Molybdenum, and Cobalt; in Phos-
phate Fertilizers and Sewa.ge Sludge"; Journal of the
A. O.A. C.; 4Jj No. 3; .1.958. ' °
3- "Air Pol.bi.tant Emission Factors"; Environmental Pro-
tection Agency; Preliminary Document; Apr., 1971.
-------
-73-
one to 10 percent /. Based on an average of 15 pounds of
particulate per ton of refuse burned and a zinc content of 2
percent, the zinc emissions to the atmosphere a,:re about
26, 200 tons per year.
1- "Air Quality Criteria for Particulate Matter"; National
Air Pollution Control Administration. Publication No.
AP-49; Jan., .1969.
-------
-74-
UPDATING OF EMISSION ESTIMATES
The emissions and emission factors presented in this report
are the result of calculations based principally on informa-
tion obtained from industrial sources. They are specifically
for the year 1969, but may be updated at any time when addi-
tional information is available. Either of the 2 methods de-
scribed herein may be used for updating; however, the longer
procedure, referred to as Method A, will yield results that
are much more reliable.
The procedures to be followed with Method A are essentially
the same as those used during the original study, which are
described briefly as follows. More than 175 inquiries were
sent to processing and reprocessing companies by mail, or
delivered during personal visits to plant sites. There was
no reply from 58 companies even after 2 or 3 follow-up let-
ters. Another 36 companies answered but did not provide
data. Some refused, but most of them claimed they did not
have the information readily available. There were 82 com-
panies that furnished all or part of the data requested, and
this was the basis for emissions and emission factors set
forth in this report.
-------
-75-
All of the companies that produce primary slab zinc were
requested to provide the essential data required for the study.
Information was obtained concerning 2 of the 5 electrolytic
plants, 3 of the 5 horizontal-retort plants, and 3 of the 4
vertical-retort plants. Based on the data obtained, emission
factors were calculated and reported for each type plant.
With respect to secondary zinc, about 50 percent of the com-
panies were contacted and the data obtained concerned nearly
30 percent of the production capacity. The reprocessing com-
panies that provided information represented about 20 percent
of the industry capacity.
Regardless of the method selected, the first step to be taken
when updating the emission estimates is to obtain the latest
issue of the Bureau of Mines Minerals Yearbook, VoJu.me I-II,
which is normally available within 16 or 18 months after the
end of the calendar year (preprints of individual sections are
usually available sooner). This publication shows the quantity
of ore mined and the zinc produced in the United States, as
well as the quantities imported and exported. It also shows
the amount of slab zinc consumed and the various purposes
fo:c which it was used. In this one publication, all of the
-------
-76-
information is available that is required to update the material
flow chart for zinc.
When using Method A, the emission factors must be revised
by contacting industry to determine the improvements in air
pollution collection equipment efficiency, and other process-
ing changes affecting zinc emissions. The revised emission
factors may then be used with the production quantities ob-
tained from'the Minerals Yearbook or other referenced sources.
Method B is considerably shorter than Method A and less reli-
able. The only requirement is to revise the material flow
chart according to the most recent published data, and apply
the emission factors shown in this report. In reality, this
method is only a partial updating. There is no determination
regarding improvements in air pollution control, a shift in
production to more efficient plants, or any other considera-
tions affecting emission factors. The advantage is that the
report can be updated within a few days rather than several
months.
To update zinc emissions from metallurgical processing,
secondary production, zinc-base alloy processing, zinc
oxide production, and the iron and steel industry, it is
-------
-77-
preferable to use Method A. The remaining emissions shown
in this report may be updated by Method B without introducing
an. appreciable error into the results.
-------
BIBLIOGRAPHIC DATA
SHEET
1. Report No.
APTD-1139
3. Recipient's Accession No.
I. Title and Subtitle
National Inventory of Sources and Emissions: Zinc - 1969
5. Report Date
May 1972
6.
7. Author(s)
W. E. Davis
8. Performing Organization Rept.
No.
>. Performing Organization Name and Address
W. E. Davis & Associates
9726 Sagamore Road
Leawood, Kansas
10. Project/Task/Worlc Unit No.
11. Contract/Grant No.
68-02-0100
12. Sponsoring Organization Name and Address
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
13. Type of Report & Period
Covered
14.
15. Supplementary Notes
16. Abstracts information is provided regarding the nature, magnitude, and extent of the
emissions of zinc in the United States for the year 1969. Background information
concerning the basic characteristics of the zinc industry has been assembled and in-
cluded. Brief process descriptions are given; they are limited to the areas that are
closely related to existing or potential atmospheric losses of the pollutant. The
zinc emissions and emission factors are based on data obtained from production and
reprocessing companies. Additional information was acquired during field trips to
inspect the air pollution control equipment and observe processing operations. Emis-
sions to the atmosphere during the year were 159,922 tons. About 31 percent of the
emissions resulted from the metallurgical processing of zinc, more than 30 percent
from the production of iron and steel, and nearly 18 percent from the incineration of
refuse. The production of zinc oxide, the wear of rubber tires, and the combustion
of coal were also significant emission sources.
17. Key Words and Document Analysis. 17o. Descriptors
Air pollution
Zinc inorganic compounds
Inventories
Exhaust emissions
Metal industry
Iron
Steels
17b- Identifiers/Open-Ended Terms
Refuse disposal
Incinerators
Coal
Oxides
Elastomers
Industrial Wastes
17e. COSATI Fie Id/Group 1 3B
18. Availability Statement
Unlimited
19.. Security Class (This
Report)
UNCL
U
' Cl
20. Security Class (This
Page
UNCLASSIFIED
21. No. of Pages
85
22. Price
PORM NTIt-SO (REV. 3-72)
USCOMM-DC I40B2-P72
-------
INSTRUCTIONS FOR COMPLETING FORM NTIS-35 (10-70) (Bibliographic Data Sheet based on COSATI
Guidelines to Format Standards for Scientific and Technical Reports Prepared by or for the Federal Government,
PB-180 600).
1. Report Number. Each individually bound report shall carry a unique alphanumeric designation selected by the performing
organization or provided by the sponsoring organization. Use uppercase letters and Arabic numerals only. Examples
FASEB-NS-87 and FAA-RD-68-09.
2. Leave blank.
3. Recipient's Accession Number. Reserved for use by each report recipient.
4- Title and Subtitle. Title should indicate clearly and briefly the subject coverage of the report, and be displayed promi-
nently. Set subtitle, if used, in smaller type or otherwise subordinate it to main title. When a report is prepared in more
than one volume, repeat the primary title, add volume number and include subtitle for the specific volume.
5- Report Date. F.ach report shall carry a date indicating at least month and year. Indicate the basis on which it was selected
(e.g., date of issue, date of approval, date of preparation.
6* Performing Organization Code. Leave blank.
7. Authors). Give name(s) in conventional order" (e.g., John R. Doc, or J.Robert Doe). List author's affiliation if it differs
from the performing organization.
8. Performing Organization Report Number. Insert if performing organization wishes to assign this number.
9. Performing Orgonization Name and Address. Give name, street, city, state, and zip code. List no more than two levels of
an organizational hierarchy. Display the name of the organization exactly as it should appear in Government indexes such
as USCRDR-I.
10. Project/Task/Work Unit Number. Use the project, task and work unit numbers under which the report was prepared.
11. Contract/Grant Number. Insert contract or grant number under which report was prepared.
12. Sponsoring Agency Nome and Address. Include zip code.
13- Type of Report and Period Covered. Indicate interim, final, etc., and, if applicable, dates covered.
14. Sponsoring Agency Code. Leave blank.
15. Supplementary Notes. Enter information not included elsewhere but useful, such as: Prepared in cooperation with . . .
Translation of ... Presented at conference of ... To be published in ... Supersedes . . . Supplements . . .
16. Abstract. Include a brief (200 words or less) factual summary of the most significant information contained in the report.
If the report contains a significant bibliography or literature survey, mention it here.
17. Key Words and Document Analysis, (a). Descriptors. Select from the Thesaurus of Engineering and Scientific Terms the
proper authorized terms that identify the major concept of the research and are sufficiently specific and precise to be used
as index entries for cataloging.
(b). Identifiers ond Open-Ended Terms. Use identifiers for project names, code names, equipment designators, etc. Use
open-ended terms written in descriptor form for those subjects for which no descriptor exists.
(e). COSATI Field/Group. Field and Group assignments are to be taken from the 1965 COSATI Subject Category List.
Since the majority of documents are multidisc iplinary in nature, the primary Field/Group assignments) will be the specific
discipline, area of human endeavor, or type of physical object. The application(s) will be cross-referenced with secondary
Field/Group assignments that will follow the primary posting(s).
18. Distribution Statement. Denote releasability to the public or limitation for reasons other than security for example "Re-
lease unlimited". Cite any availability to the public, with address and price.
19 8. 20. Security Classification. Do not submit classified reports to the National Technical
21. Number of Pages. Insert the total number of pages, including this one and unnumbered pages, but excluding distribution
list, if any.
22. Price. Insert the price set by the National Technical Information Service or the Government Printing Office, if known.
FORM NTIS-39 (REV. 3-721 USCOMM-DC I40B2-P72
&U.S. G.P.O.: 1973—746-770/4173, Region No. 4
------- |