U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
>•
Consumer Protection and Environmental Health Service
SSSSSSS&S: W:w^^
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AIR POLLUTION ASPECTS
OF
BRASS AND BRONZE SMELTING
AND REFINING INDUSTRY
Brass and Bronze Ingot Institute
and
National Air Pollution Control Administration
U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Consumer Protection and Environmental Health Service
National Air Pollution Control Administration
Raleigh, North Carolina
November 1969
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The AP series of reports is issued by the National Air Pollution Con-
trol Administration to report the results of scientific and engineering
studies, and information of general interest in the field of air pollution.
Information reported in this series includes coverage of NAPCA intra-
mural activities and of cooperative studies conducted in conjunction
•with state and local agencies, research institutes, and industrial
organizations. Copies of AP reports may be obtained upon request,,
as supplies permit, from the Office of Technical Information and Pub-
lications, National Air Pollution Control Administration, U.S. Depart-
ment of Health, Education, and Welfare, 1033 Wade Avenue, Raleigh,
North Carolina 27605.
National Air Pollution Control Administration Publication No. AP-58
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, B.C., 20402 - Price 35 cents
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PREFACE
To provide reliable information on the air pollution aspects of the
brass and bronze ingot industry, the Brass and Bronze Ingot Institute
(BBII) and the National Air Pollution Control Administration, Public
Health Service, U. S. Department of Health, Education, and Welfare
entered into an agreement on May 29, 1967. A cooperative program
•was established to study atmospheric emissions from the various
industry processes and publish information about them in a form help-
ful to air pollution control and planning agencies and to brass and
bronze industry management. Direction of this study was vested in a
BBII-NAPCA Steering Committee composed as follows
Representing NAPCA Representing BBII
Stanley T. Cuffe* Earl S. Schwartz*
John L. McGinnity George E. Heizman, Jr.
Guntis Ozolins Irving Tanenberg
Information in the report describes the nature and range of
atmospheric emissions during normal operating conditions and the per-
formance of established devices and methods employed to limit and
control these emissions.
*Principal representatives.
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ACKNOWLEDGMENTS
Many companies and individuals in the brass and bronze ingot
industry have been helpful in providing plant visits and questionnaire
data for the study.
Special thanks are due to H. Kramer and Co. and R. Lavin and
Sons, Inc. , for their participation in a program of stack sampling and
analysis specifically for this study.
The sponsors also wish to acknowledge the contributions of the
principal author, Mr. Robert A. Herrick of Resources Research, Inc.
and of the source testing personnel of the Division of Abatement,
National Air Pollution Control Administration.
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CONTENTS
SUMMARY 1
Manufacturing Processes .... l
Emissions from Brass and Bronze Production 2
Control of Emissions 3
Etaission Guidelines 3
GROWTH OF THE BRASS-AND BRONZE-REFINING INDUSTRY 5
INGOT-MANUFACTURING PROCESSES 9
Raw Materials . 9
Raw Material Preparation .... 9
Mechanical Methods . 11
Hand Sorting 11
Stripping 11
Shredding 11
Magnetizing 11
Briquetting . . . 11
Pyrometallurgical Methods (Heat) 11
Sweating 11
Burning 11
Drying 12
Blast Furnace or Cupola 12
Hydrometallurgical Methods (Water) 12
Concentrating 12
Ingot Production . . 13
Types of Furnaces 14
Reverberatory Furnaces 14
Rotary Furnaces 15
Crucible Furnaces 16
Ingot Pouring and Miscellaneous 16
AIR POLLUTANTS GENERATED CAUSE AND CONTROL. . . 19
General Character of Emissions 19
Raw Materials 21
Raw Material Preparation 21
Sweating 21
Burning 21
Drying 22
Blast Furnaces 22
Smelting and Refining 22
Heating 23
Charging 23
Melting. 24
Refining 24
Alloying 26
Pouring of Ingots ' 26
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PRESENT CONTROL SYSTEMS . . ... 29
Availability and General Use • • ^
Design of Control Systems . • ^
Baghouse Operation. . . ... 33
Instrumentation . . 34
Maintenance ^5
Costs 36
Emissions Data NAPCA Tests .... . . . . 37
Test A 37
Test B 38
Test C 39
Test D . . . ... 39
Test E 40
Test F . . . . 40
Test G . . . . 41
Tests H and I 41
Other Data . . . . . 42
REFERENCES 49
APPENDICES 51
A. NAPCA Sampling Procedures 53
B. NAPCA Test Data 57
C. Members of Brass and Bronze Ingot Institute 63
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AIR POLLUTION ASPECTS
OF BRASS AND BRONZE SMELTING
AND REFINING INDUSTRY
SUMMARY
This state-of-the-art survey covers information made available
through members of the Brass and Bronze Ingot Institute (BBII) and
from field studies conducted by the National Air Pollution Control
Administration (NAPCA). Brass and bronze are generally considered
to be copper-base alloys with zinc and tin, respectively, as the largest
secondary components. Members of the Brass and Bronze Ingot Insti-
tute produce 31 standard copper-base alloys.
There are approximately 60 producers of brass and bronze ingots
in the United States. In the years since World War II, the production
of brass and bronze ingots has been fairly constant, averaging slightly
more than 300, 000 tons annually. The 12 BBII member plants repre-
sent some 40 percent of this total production. A questionnaire survey
of the BBII members revealed that substantive data were sparse, and
so an emission test program was instituted by the National Air Pollu-
tion Control Administration. The resultant test data are the basis for
most of the conclusions drawn in this report.
The "ingot" manufacturers are naturally tied closely to the
overall secondary copper industry. As of 1961, in addition to ingot
makers, the industry consisted of several thousand dealers and
collectors, several thousand foundries, about a dozen primary
smelters using scrap and mineral concentrates, and several second-
ary smelters using scrap only. These plants are located mostly in
the Northeastern States, the Pacific Coast States, and the East North
Central States. A few plants are located in the Southern and West
Central States.
MANUFACTURING PROCESSES
Obsolete domestic and industrial copper-bearing scrap is the
basic raw material of the brass and bronze ingot industry. Scrap as
received is frequently not clean and may contain any number of metal-
lic and non-metallic impurities. These impurities can be removed by
mechanical methods such as hand sorting or magnetizing, heat methods
such as sweating or burning, or gravity separation in a water medium.
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Brass and bronze ingots are produced from a. number of types of
furnaces through, a combination of melting, smelting, refining, and
alloying of the processed scrap material. Reverberatory, rotary,
or crucible furnaces are used, depending on the size of the melt and
the desired alloy. Stationary reverberatory furnaces refine batches,
or heats, of up to 100 tons in 24- to 48-hour periods. When such
large amounts of a single alloy are not required, the cylindrical
"rotary" furnace is more often used. Whereas the reverberatory
furnaces are usually built for 50 tons or more, capacities of the
rotary furnaces range from only a few tons up to perhaps 30 or 40
tons. Both of these furnaces are normally heated by direct firing,
in which process the flame and gases come into direct contact with
the melt. Processing is essentially the same in any furnace except
for the differences in the types of alloy being handled. Crucible
furnaces are usually much smaller, whether electric or non-electric,
and are used principally for small quantities of special-purpose
alloys.
EMISSIONS FROM BRASS AND BRONZE PRODUCTION
The principal source of atmospheric emissions in the brass and
bronze ingot industry is the refining furnace. The exit gas from the
furnace may contain the normal combustion products such as fly ash,
soot, and smoke. The use of low-sulfur fuel results in trace amounts
of sulfur oxide emissions. Because zinc is a major low-boiling-point
alloying constituent, appreciable amounts of zinc oxide are normally
present in the exit gases also.
Analysis of dust collector catch indicates that from 56 to 96
percent of the collected dust is zinc oxide. About 6 to 8 percent is
lead oxide along with lesser amounts of other metallic oxides. These
small particles are in the submicron range, wherein they have the
greatest opacity to light; therefore, the uncontrolled emissions form
dense plumes.
Limited data indicate that concentrations of dust from "brass
furnaces" may range from 0. 05 to 4. 1 grains per standard cubic foot
(scf). Concentrations as large as 20 grains per cubic foot may be
expected during the use of compressed air beneath the molten metal.
The average daily discharge of particulate emissions from a
typical 50-ton reverberatory brass ingot furnace, covering a variety
of alloy formulations, is 3, 000 to 4, 000 pounds, based upon an
industry average-emission factor of 60 to 80 pounds of particulate
per ton of ingots produced. On any individual heat the amount may
vary widely. The results of recent NAPCA tests on reverberatory,
rotary, and cupola furnaces show emissions ranging from 20 to 157
pounds per ton. From an annual production of 300, 000 tons of ingots,
the emission potential is about 10, 000 tons of particulate. Other
sources of particulate emissions include the preparation of raw
materials and the pouring of ingots.
BRASS AND BRONZE INDUSTRY
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CONTROL OF EMISSIONS
The only air pollution control equipment to receive general
acceptance in. the brass and bronze ingot industry is the baghouse
filter collector. The emissions from-a baghouse in satisfactory
condition are usually invisible. The concentration of dust being
emitted from one Los Angeles installation was only 0. 004 grain per
cubic foot. Recent NAPCA data indicate particulate concentrations
between 0. 006 and 0. 036 grain per standard cubic foot. These
NAPCA tests were at operating baghouse installations under typical
conditions.
Cost for installation of a baghouse depends to a large extent
upon the auxiliary equipment required for proper ductwork, hooding,
gas cooling equipment, and so forth. The baghouse itself is only a
part of the total cost. Reports indicate installed costs for dust
collection systems of up to $5. 00 or more per cubic foot per minute
capacity.
Information from a few installations that use wet scrubbers and
electrostatic precipitators indicates that significant maintenance
problems and low efficiency have been encountered. Recent develop-
ment workmen these dust collector systems may make them more
applicable in the future.
Most of the material preparation processes involving mechanical
or wet treatment do not produce air pollutants. Some heat treatment
operations produce emissions that are combustible. These fumes
may be satisfactorily controlled by an afterburner or by secondary
combustion techniques.
EMISSION GUIDELINES
In spite of wide variations in types of furnaces, charge materials,
and operating conditions, the major component of the emissions in
nearly every case is zinc oxide. Typically, from 60 to 95 percent of
the total material collected from brass and bronze smelting emissions
is zinc oxide.
The generally accepted air pollution control device for this
industry is the baghouse. Filter ratios of 2. 0 to 2.7 cfm/ft2 and
pressure drops of 2 to 6 inches are usually encountered. The
cooling of gases prior to filtration is a major engineering design
consideration because the filter materials burn or melt at excessive
temperatures. Too low a temperature, on the other hand, causes
water condensation and consequently clogging of the filter. Typical
operating temperatures for some filter materials are as follows:
Filter fabric
Cotton
Dacron, heat-set
Glass fiber
Orion, heat-set
Wool, treated
Peak temperature, °F
180
300
600
300
240
Operating temp. , °F
160
275
500
27.0
220
Summary
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The source testing studies show that it is possible to reduce exit
particulate emissions to between 0. 01 and 0. 03 grain per scf with
no visible emissions.
The major air pollution control problem is the capture and
ducting of fume emissions from the furnaces to the baghouses.
Capturing the dust-laden gases generated during charging and
pouring operations is particularly difficult. Ultimate control of air
pollution and occasional in-plant contamination may require changes
in furnace design, new metallurgical processes, or new technology
for the capture of fumes at the point of generation.
BRASS AND BRONZE INDUSTRY
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GROWTH OF THE BRASS
AND BRONZE REFINING INDUSTRY
Copper alloys have served the needs of mankind in many useful
and decorative ways throughout recorded history. The terms "brass"
and "bronze," today, are inaccurate descriptions of metallic content
that have been passed down through historical usage. Brass has
been generally considered to be an alloy of copper in which zinc is
the principal alloying material. Bronze has been considered to be
an alloy in "which tin is the largest secondary component. In
actuality this is no longer necessarily true.
The variety of copper alloys that can be made is virtually
infinite, especially when secondary metals are recovered from a
complete variety of scrap materials. Over the years it has been
found advantageous to classify many of the standard scrap materials
as well as the finished ingots being produced. The recovery of these
alloys constitutes a major contribution to our economy because the
domestic production of virgin metals would not meet the demand for
copper-base alloys in this country. U. S. Bureau of Mines statistics
indicate that secondary copper (recovered from scrap) was produced
in quantity approx-imately equal to new production of copper from
domestic ores during the 1950's.
The secondary copper industry is composed of many groups,
including dealers, collectors, foundries, ingot makers, and
smelters. "Secondary" refers only to origin and not to quality. The
shortages existing after World Wars I and II led to an acceptance
and rapid growth of the recovery industry.
Brass and bronze ingot manufacturing covers only a portion of
the overall "secondary copper industry, " though there appears to be
some overlapping of the recovery processes. This usually depends
upon the economic situation and the condition in which copper scrap
is available.
Following surveys in 1939, 1947, and I960, the Brass and Bronze
Ingot Institute has adopted a list of 31 standard alloys that are now
produced by the members of that organization. The BBII list of basic
alloys and their nominal compositions-'- is presented in Table 1. This
list parallels other lists of ingot and product specifications such as
those of the American Society for Testing and Materials (ASTM), the
Federal Stock Catalog, and the U.S. Department of Defense. Many
other alloys are produced when needed.
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Table 1. NOMINAL CHEMICAL SPECIFICATIONS FOR BBII STANDARD ALLOYS
Alloy
No. Classification
1A Tin bronze
IB Tin bronze
2A Leaded tin bronze
2B Leaded tin bronze
2C Leaded tin bronze
3A High-lead tin bronze
SB High-lead tin bronze
3C High-lead tin bronze
3D High-lead tin bronze
3E High-lead tin bronze
4A Leaded red brass
4B Leaded red brass
5A Leaded semi-red brass
SB Leaded semi-red brass
6A Leaded yellow brass
6B Leaded yellow brass
6C Leaded yellow brass
7A Manganese bronze
8A Hi-strength mang. bronze
SB Hi-strength mang. bronze
8C Hi-strength mang. bronze
9A Aluminum bronze
9B Aluminum bronze
9C Aluminum bronze
9D Aluminum bronze
IDA Leaded nickel brass
10B Leaded nickel brass
11A Leaded nickel bronze
11B Leaded nickel bronze
ISA Silicon bronze
12B Silicon brass
Cu, %
88-.0
88.0
88.0
87.0
87.0
80.0
83.0
85.0
78.0
71.0
85.0
83.0
81.0
76.0
72.0
67.0
61.0
59.0
57.5
64.0
64.0
88.0
89.0
85.0
81.0
57.0
60.0
64.0
66.5
88.0
82.0
Sn,%
10.0
8.0
6.0
8.0
10.0
10-0
7.0
5.0
7.0
5.0
5.0
4.0
3.0
2.5
1.0
1.0
1.0
1.0
2.0
3.0
4-0
5.0
Pb,%
1.5
1.0
1.0
10.0
7.0
9.0
15.0
24.0
5.0
6.0
7.0
6.5
3.0
3.0
1.0
1.0
9.0
5.0
4.0
1.5
Zn,%
2.0
4.0
4.0
4.0
2.0
3.0
1.0
5.0
7.0
9.0
15.0
24.0
29.0
37.0
37.0
39.0
24.0
24.0
20.0
16.0
8.0
2.0
5.0
14.0
Fe, %
1.0
1.0
3.0
3.0
3.0
1.0
4.0
4.0
1.5
Al,%
0.6
1.0
5.0
5.0
9.0
10.0
11.0
11.0
Ni,%
2.0
4.0
12.0
16.0
20.0
25.0
Si,%
4.0
4.0
Mn,%
0.5
1.5
3.5
3.5
0.5
3.0
1.5
Each of the classes of copper-base alloys has characteristics
making it particularly suitable for products that may be subjected
to different stresses, corrosion, or machining operations. Tin
bronze and leaded tin bronze are very corrosion7resistant and have
good casting characteristics. High-leaded tin bronzes are malleable
and are readily machined. Red and semi-red brasses are especially
useful in products for water systems, such as valves, meters, and
fittings because they are inexpensive, corrosion-resistant, and have
good casting and machining characteristics.
Yellow brasses are moderately strong and have excellent
machining and polishing characteristics. Manganese bronze has
especially good tensile strength and corrosion resistance to sea
water. Aluminum bronzes also have high tensile strength and
hardness and are resistant to fatigue and to high temperature. The
aluminum bronzes containing nickel are particularly suitable for
marine pumps and propellers because of their resistance to corrosion
and cavitation.
BRASS AND BRONZE INDUSTRY
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Leaded nickel brass and bronze are silvery in color, have
excellent mechanical properties, and are tarnish and corrosion
resistant. Silicon bronze and brass have expecially good casting
characteristics. Dross formation is minor, leaving clean casting
surfaces.
Since World "War II, the production of brass and bronze ingots
has been fairly constant and has averaged slightly more than
300, 000 tons per year for the past 20 years (from a low of 203, 000
tons in 1949 to a high of 360, 000 tons in 1966). Table 2 shows the
annual production of brass and bronze ingots as reported to the
Bureau of Mines, U. S. Department of the Interior. 2
Table 2. U. S. PRODUCTION OF BRASS AND BRONZE INGOTS
DURING THE PERIOD 1947 THROUGH 1966
Year
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
Ingot production, tons
284.800
300,300
203,400
346,900
366,600
319,700
305,400
291,800
335,900
316,800
284,100
261,200
293,100
266,000
270,000
272,300
291,200
308,500
333,500
360,600
Growth of the Brass- and Bronze-Refining Industry
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INGOT-MANUFACTURING PROCESSES
RAW MATERIALS
The basic raw material of the brass and bronze ingot industry
is not ore or virgin metals but rather copper and copper-base alloy
scrap. About two-thirds of the amount of secondary copper recov-
ered is in the form of the brasses and bronzes, while one-third is in
the form of copper alone.
Both the ingot industry and the American Society for Testing
and Materials have made a continuing effort over the past 30 years
or so to reduce the number of varieties of copper-base alloys. The
classification of scrap metal is an important step in the production
of brass and bronze ingots. Of the many hundreds of copper-base
alloys that become available for reuse through scrap recovery
channels,, 54 primary types of copper-bear ing scrap are now included
in the standards published by the National Association of Secondary
Material Industries. These are listed in Table 3.
The ingot manufacturer is faced not only with many classes of
scrap metal to refine and blend but also with a great deal of non-
metallic material that contributes nothing to the composition of the
ingot and that increases the problems in producing a high-quality
product. Among these undesirable materials are oil, grease, paint,
insulation, rubber, antifreeze, chemicals, and many others. As
more uses are found for copper-base alloys, the variety of undesir-
able and contaminating materials arriving in scrap recovery channels
increases correspondingly.
Scrap dealers often provide the ingot manufacturer with an
approximate classification of each lot of scrap sold, based princi-
pally on a quick visual check and experience. Larger scrap dealers
are able to sort and segregate scrap into more precise classifica-
tions by using procedures such as examining metal color and
structure, filing and drilling, chemical spot tests, and quick chem-
ical analysis. Ingot manufacturers must classify, segregate, and
analyze scrap shipments by additional methods, which may include
sampling and melting for spectrographic analysis of alloys not
readily identifiable.
RAW MATERIAL PREPARATION
Before the scrap metal is blended in a furnace to produce the
desired ingots, removal of some of the nonmetallic contaminants
or, in some instances, preprocessing the raw material to yield
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Table 3. TYPES OF COPPER-BEARING SCRAP
No.
Designation
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41-
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
clean fired
clean muffled (popped)
No. 1 copper wire
No. 2 copper wire
No. 1 heavy copper
Mixed heavy copper
Light copper
Composition or red brass
Red brass composition turnings
Genuine babbitt-lined brass bushings
High-grade, low-lead bronze solids
Bronze papermill wire cloth
High-lead bronze solids and borings
Machinery or hard red brass solids
Unlined standard red car boxes (clean journals)
Lined standard red car boxes (lined journals)
Cocks and faucets
Mixed brass screens
Yellow brass scrap
Yellow brass castings
Old rolled brass
New brass clippings
Brass shell cases without primers
Brass shell cases with primers
Brass small arms and rifle shells,
Brass small arms and rifle shells,
Yellow brass primer
Brass pipe
Yellow brass rod turnings
Yellow brass rod ends
Yellow brass turnings
Mixed unsweated auto radiators
Admiralty brass condenser tubes
Aluminum brass condenser tubes
Muntz metal tubes
Plated rolled brass
Manganese bronze solids
New cupro-nickel clippings and solids
Old cupro-nickel solids
Soldered cupro-nickel solids
Cupro-nickel turnings and borings
Miscellaneous nickel copper and nickel-copper-iron scrap
New monel clippings and solids
Monel rods and forgings
Old monel sheet and solids
Soldered monel sheet and solids
Soldered monel wire, screen, and cloth
New monel wire, screen, and cloth
Monel castings
Monel turnings and borings
Mixed nickel silver clippings
New nickel silver clippings and solids
New segregated nickel silver clippings
Old nickel silver
Nickel silver castings
Nickel silver turnings
more efficient and economical utilization of the scrap may be
desirable. These processes maybe either mechanical or pyro-
metallurgical or hydrometallurgical.
10
BRASS AND BRONZE INDUSTRY
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Mechanical Methods
1. Hand Sorting is usually done as scrap is unloaded and
placed into storage. This can be done by the types of objects
(faucets versus industrial valves), their color (red versus yellow-
brass), and other visual clues that come with years of experience.
2. Stripping is a method used to remove the insulation or
other coverings, particularly from copper cables. This can be
done by hand or with machines.
3. Shredding is a recently developed process whereby material
such as insulated copper wire is introduced to a hammermill, which
achieves the separation of metal from other materials. Insulation
is removed by air sweeping, and cyclones are necessary to prevent
atmospheric contamination. Capital cost is high, and hence, this
operation will probably not be found in small plants.
4. Magnetizing simply employs conveyors and magnetized
pulleys to remove gross or tramp iron particles from brass
borings and small items of brass scrap.
5. Briquetting forms small bales from bulky scrap. It is
accomplished by powerful hydraulic presses. Compression of this
type of scrap permits more compact storage plus easier handling
and loading into furnaces. Rapid melting of compressed scrap
involves minimum oxidation of the metal.
Pyrometallurgical Methods (Heat)
1. Sweating is the removal of low-melting-point metals such
as lead, solder, and babbitt metal. This may be done by heating
in a furnace, which is commonly designed with an open hearth and
sloping bed so that the charge is placed on the high side. This
placement permits the low-melting components to flow toward the
lower end and be collected. Sweating is becoming less economical
as improvements are made in radiator construction because less
tin and solder are available for separation into valuable lower-
melting-point fractions. A sweating furnace is shown in Figure 1.
2. Burning is the removal of insulation that is not mechanically
stripped from wire or cable and that requires carefully controlled
burning for removal. This may more properly be considered part
of the scrap preparation problem, but this type of scrap material
often reaches storage areas and becomes a problem in the manufac-
ture of ingots.. Many different types of materials are used for
insulation. The burning of some of these materials may create an
air pollution problem. Burning polyethylene and polypropylene
insulation does not require high temperatures, and the combustion
products are not harmful, being largely carbon dioxide and water.
Polyvinyl chloride insulation has, however, much higher resistance to
flame and thereby requires much more heat input for combustion.
Its combustion products include carbon dioxide, water, phthalic
anhydride, and hydrogen chloride. Fluorocarbon insulation may
Ingot-Manufacturing Processes
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Figure 1. Tunnel-type sweating furnace.
(Cou'tesy H. Krotner ond Company)
release hydrogen fluoride when burned. Some of these chemicals
are highly toxic and corrosive.
3. Drying involves the use of a heated rotary kiln to vaporize
excess cutting fluids from machine shop chips or borings. This
must be done carefully to prevent high temperatures that would warp
the steel kiln and begin to cause oxidation on the large surface area
exposed on the metal chips.
4. Blast Furnace or Cupola. Although the names are sometimes
used interchangeably, the cupola can be used simply to melt down
metal or reduce oxides, whereas the blast furnace reduces an ore or
metal oxide to the molten metal. A blast furnace is shown in Figure 2.
The industry furnaces recover metal from skimmings, slags, and so
forth, and the reducing atmosphere allows direct reduction of metallic
oxides. Coke is employed both as fuel and reducing agent through the
production of carbon monoxide. The dense molten metal settles from
the nonmetallic glass-like slags. The resulting metals (black copper
or cupola melt) must be further refined in the ordinary furnaces to
produce a finished ingot alloy.
Hydrometallurgical Methods (Water)
1. Concentrating is the process by which the metallics in fine
12
BRASS AND BRONZE INDUSTRY
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materials are recovered through differences in density. Although
the total loss of metal is greater than in the blast furnace, this
method is well adapted to fines that might be blown out of the furnace.
It involves grinding, screening, and gravity separation in a water
medium. There is no air pollution, but water pollution must be
carefully avoided.
r
Figure 2. Blast furnace for smelting copper-base scrap slag and residues.
{Courtesy H. Kramer and Company)
INGOT PRODUCTION
Brass and bronze ingots are produced from a number of types
of furnaces through a combination of melting, smelting, refining,
and alloying of the processed scrap material. Virgin metals are
used at times as additional raw material to obtain the specifications
desired. They may be used in diluting certain elements that cannot
be refined out of the metal and in increasing the percentage of a
desired constituent that may be deficient in the initial scrap charge.
Basic to the processes is the fact that air pollutants are generated.
The scrap raw materials contain both metallic and nonmetallic impuri-
ties that must be removed in order to produce ingots of desired
specifications. Smelting and refining are the processes by which these
impurities are removed. If these materials cannot be removed as part
Ingot-Manufacturing Processes
13
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of a slag or flux covering, then they will usually be emitted as part of
the hot gas stream and become part of the air pollution problem.
One of the most common methods of removing metallic impuri-
ties is to introduce compressed air beneath the surface of the molten
metal. This violent agitation is almost sure to produce large
quantities of finely dispersed air pollutants in the exhaust gas stream.
The introduction of combustible ingredients with the scrap metals
is also likely to produce air pollutants. These operations are
inescapable and inherent in the normal operations required to pro-
duce high-quality brass and bronze ingots.
Types of Furnaces
Furnaces used for ingot production include reverberatory,
rotary, and crucible furnaces. There is little real difference in
the melting, refining, and alloying actions in these furnaces, but
there are substantial differences in capacities and methods of
charging and heating. There are also differences in the air pollu-
tion potential of the various units and the applicability of control
procedures .
Reverberatory Furnaces may be stationary or tilting. A
reverberatory furnace is a large rectangular box-like structure,
refractory lined, that uses direct firing to heat the charge by
conduction and radiation. The lining depends upon the manufac-
turer's experience, the types of alloys and fluxes, and other
factors. Charging may be either by side door or by an overhead
door, as in Figure 3.
Figure 3. Reverberatory furnace for melting and retimng copper ana orass scrap.
Designed for charging through roof doors.
(Courtesy H. Kramer and Company)
14
BRASS AND BRONZE INDUSTRY
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The capacity of a stationary reverberatory furnace may be as
much as 100 tons or more per heat or charge. Reverberatories
are the basic production unit for large runs of the more common
copper-base alloys. A charge of scrap metal is made at the
beginning of the heat and at intervals during the melt-down period.
Melting is done as rapidly as possible and may be done in oxidizing
or reducing atmospheres, depending upon the types of scrap, alloy,
and other factors. Burner fuels are often enriched with oxygen to
increase the rate of melting. The fuel is normally gas or low-
sulphur-content fuel oil. A fairly light and fluid slag cover helps in
reducing volatilization and oxidation losses.
Rotary Furnaces (Figure 4) can be either tilting, nontilting, or
capable of complete 360-degree rotation. They are cylindrical and
lined with refractory material. Heat is supplied by movable gas
or fuel oil burners. The charging, alloying, fluxing, and sampling
procedures are similar to those used with the reverberatory furnace.
Figure 4. Gas-fired rotary brass melting furnace.
{Courtesy H. Kramer and Company)
Ingot-Manufacturing Processes
15
-------
They are usually somewhat smaller than reverberatories, frequently
having capacities of 15 to 20 tons per heat, though they may be as
large as 50 tons per heat. The rotary or rocking action promotes
rapid heat transfer and lengthens refractory life by spreading the
slag line over charging areas. Charging ports may be located on
the side, top, or end of the cylinder.
Crucible Furnaces are most useful for melting small quantities
of clean scrap and for refining specialized alloys, but they can be
used for common alloys as well. The gas- or oil-fired crucible has
a steel cylindrical furnace shell lined •with refractory material,
inside of -which the crucible is mounted. These furnaces use indirect
firing; that is, the flame is aimed tangentially into the annular combuS'
tion space between the crucible and the refractory lining, heating the
crucible's contents without contacting the charge.
Electric crucible furnaces use either high- or low-frequency
induction heating. They are especially well adapted to rapid
melting of small batches. Heating is due to the resistance to the
flow of electrical currents induced in the charge by high-frequency
electric currents in an induction coil surrounding the crucible or
with low-frequency heating, by currents induced by an insulated
•water-cooled iron core transformer under the crucible. A certain
amount of mechanical turbulence is caused in the low-frequency
type by reaction of primary and secondary magnetic fields. The
relatively higher cost of electrical equipment and energy is offset to
some degree by high speed of melt and excellent temperature control,
especially for relatively small heats of special alloys.
The direct-heating furnaces such as rotaries and reverberatories
have greater fuel efficiency than the indirect-heating furnaces such
as the gas- or oil-fired crucibles and the electric induction furnaces.
Direct-fired furnaces are, however, invariably more difficult to
control with regard to dust, smoke, and fume losses. Since they
are also much larger, they are usually the primary sources of air
pollution from the plant.
INGOT POURING AND MISCELLANEOUS
Samples of the furnace melt are taken as the refining operation
progresses. As soon as analysis indicates that the correct grade
has been achieved and that the melt is at proper temperature,
pouring of ingots is begun. In most instances the metal molds are
handled by a semiautomatic system. Metal from the furnace is
tapped into some sort of holding ladle, and this is tilted by an
operator to fill one or several molds as they pass by. This
arrangement can be varied in a number of ways, the method being
adapted to the quantity of alloy being prepared.
The line of molds may be movable or stationary. When a
large reverberatory furnace is tapped, an automated line of molds
is commonly used. Several are filled at once by operator control;
16 BRASS AND BRONZE INDUSTRY
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the next section is moved into position; time is allowed for cooling;
water sprays are used for final cooling; the ingots are removed and
conveyed to temporary container boxes; the mold cavities are
cleaned and, if necessary, lined; pretreatment material such as
charcoal is added; then the molds are taken back to the pouring
station.
In the process of melting, smelting, refining, pouring, and
so on, several miscellaneous operations may occur. Coverings
of molten slags and fluxes are sometimes formed. A flux is not
necessarily a slag but is a chemical added to accomplish a
metallurgical purpose, though at times they may both act as liquid
covers. Figure 5 illustrates the reduction in zinc loss accomplished
by a cover. These covers, which are eventually removed along with
drosses and skimmings, contain metal and are reprocessed for
the ultimate recovery of the metal.
H-777W+
Figure 5. Transfer crucibles, with cover and without.5
More detailed descriptions of these processes are included in
numerous references containing additional information on brass
CO
and bronze production. °
Ingot-Manufacturing Processes
17
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AIR POLLUTANTS GENERATED -
CAUSE AND CONTROL
GENERAL CHARACTER OF EMISSIONS
The various types of ingot furnaces and intermediate processes
such as blast furnaces have individual operating problems with
regard to the generation and control of air pollutants within the
plant. Direct-fired furnaces create greater problems in this
respect than indirect-fired furnaces because of the open flames
impinging on the scrap metals. The large reverberatory and
rotary furnaces produce the greatest quantity of pollutants because
of their large capacity per heat and the volume and high velocity
of their combustion gases. Large or small, rotary or reverber-
atory, the amount of particulate emission from any kind of brass
furnace is roughly proportional to the amount of zinc contained
in the furnace and the amount of charging and refining that must
be done to bring the alloy into the required chemical specification.
Emissions that may contribute to atmospheric pollution are
released from various operations in a brass or bronze ingot plant.
Included are the handling and concentrating of raw materials; the
burning of oil, grease, and insulating materials; the refining and
concentrating of low-grade scrap and metallurgical wastes in a
blastfurnace; plus the firing up, charging, alloying, and pouring
operations connected with the ingot furnaces themselves. Solid
and liquid particulates such as fly ash, carbon particles, mechan-
ically produced dust, unburned fuel oil mist, and particularly,
metallic fumes produced from the oxidation of some of the more
volatile alloying constituents are among the types of emissions that
need to be controlled. The types and ranges of emissions depend
on factors such as fuel, composition and melting temperature of
the alloys., types of furnace, and various operating factors such
as methods of charging, melting, refining, removing slag, adding
alloy metals, and pouring the ingots. A typical analysis of fumes '
emitted and caught in baghouse filters is shown in Table 4.
Particulates other than metallic fumes are not generally
considered too troublesome to control, but the particle size of zinc
and other oxide fumes requires the use of extremely efficient air
pollution control equipment. The particle size is in the range of
0. 03 to 0. 5 micron. The individual particles tend to form lace-
like agglomerate structures, as shown in Figure 6. The dense
white plume so characteristic of zinc oxide is due in large measure
19
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Table 4. RANGE OF CHEMICAL ANALYSIS
OF DUST COLLECTED BY A BRASS AND
BRONZE SMELTER BAGHOUSE5
Element
Zinc
Lead
Tin
Copper
Chlorine
Sulfur
Composition range, %
45.0 to 77.0
1.0 to 12.0
0.3 to 2.0
0.05 to 1.0
0.5 to 1.5
0.1 to 0.7
*• 3U •'
14
Figure 6. Electron photomicrographs of fume from zinc smelter.6
to the fact that maximum scattering of light is caused by particles
from 0. Z to 0. 5 micron in diameter. °-
Gaseous emissions from ingot plants include the oxides of
carbon (principally carbon dioxide but including some monoxide),
nitrogen, and sulfur (if the fuel contains sulfur). The sulfur
content of natural gas is too small to cause sulfur oxides to be
emitted in objectionable quantities, but fuel oil can have an apprec-
iable sulfur content. Limited source testing datalO indicate that
trace amounts of NO2, H2S, and halogens are present in concen-
trations of below 1 ppm.
20
BRASS AND BRONZE INDUSTRY
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RAW MATERIALS
Although the nature of the scrap metal has much to do with
the ultimate emissions, most of it arrives in solid forms not
likely to cause pollution. Pipe, chunks, casting, and so forth,
cause no problem. Borings, chips, and grindings become
progressively smaller, but they are usually associated with cut-
ting oils and are not likely to produce dust. A very few scrap
items might cause dust in handling. When slags and other similar
materials are handled, there can be fugitive dust, but this is not
much different from handling a pile of sand or other minerals.
Emissions should be negligible except during periods of very dry,
windy weather. Fuel, such as gas or oil, arrives by pipeline.
Coke for the blast furnace contains a minimum of dust.
RAW MATERIAL PREPARATION
The mechanical methods of processing scrap, as described
under manufacturing processes, should cause little or no
pollutant problems. The hydrometallurgical process of concen-
trating must be carefully controlled to prevent water pollution.
Pyrometallurgical processes all create air pollutants to some
degree.
Sweating
Sweating is carried out at medium temperatures because only
the solders and low -melting -point constituents are to be melted,
not the entire radiator. Metal fume losses are very low, but
fumes and combustion products of antifreeze residues, soldering
salts, and hose connections •will be drawn into the collection
system. 7 Sweating furnaces are infrequently provided with wet
scrubbers using a slightly alkaline spray or •with afterburners.
Burning
"When a separate operation is set up for burning off the
insulation from wire it should properly be considered as prepara-
tion of scrap rather than as the manufacture of ingots. Little
information is available concerning these emissions. An effective
scrubber must be used when insulations containing halogens are
burned so that dangerous fumes -will be prevented from reaching
the atmosphere."^ Source tests in Los Angeles indicate that
uncontrolled emissions can be dense black smoke containing
particulate matter in concentrations as large as 29 grains per scf
at 12 percent COg. Control of these emissions, largely combus-
tible matter, by the use of secondary combustion at 2, 000° F
resulted in emissions with concentrations of particulate matter as
small as 0.16 grain per scf at 12 percent CC»2 and with smoke
opacities of 0 to 10 percent white. 8 The addition of these materials
to the ingot furnace -will be considered under " charging. "
Aii Pollutants Generated - Cause and Control 21
-------
Drying
The removal of cutting oils from chips and borings creates
considerable amounts of hydrocarbons. The nature of the combus-
tion process that eliminates these hydrocarbons will determine
whether fumes and soot escape or whether emissions are clean
and fully oxidized. The vaporized fumes must be burned in
afterburners to oxidize the hydrocarbons and prevent air pollution.
Afterburners placed on this type of emission source have been
observed, and no emissions were visible. °
Blast Furnaces
The blast furnace (or cupola) produces a concentrated product
called "black copper" or "cupola melt" from low-grade materials
such as slag and skimmings. The product actually has variable
proportions of copper, tin, lead, zinc, nickel, and other metals.
This is a. cheaper process than {he ingot furnaces in which to
recover the metallic values in the low-grade feed materials. The
blast furnace is not common in the smaller ingot-producing com-
panies. Operation on a 24-hour basis is normally advantageous
•with relatively large quantities of material.
The charge is introduced at the top of a. vertical furnace, along
with coke for fuel and a reducing agent, plus limestone or other
materials for fluxing. Slag and concentrated alloy are tapped near
the bottom of the furnace. Slag is often tapped continuously while
metal is obtained at intervals! A large volume of air is introduced
through tuyeres spaced around the periphery of the furnace. Tem-
peratures in the smelting zone are sufficient to reduce oxides to
molten metal. These temperatures drop rapidly as the gas rises
through the charge material to the top of the furnace.
Fumes and dust from the blast furnace or cupola are similar
to those from the ingot furnaces. The particulate matter and
gases emitted from the blast furnace are likely to be rather
variable because of the large variety of scrap, slag, skimmings,
and spills that are processed. Limited data from three samples
indicated that particulate matter reaching the baghouse ranged from
35 (following a sand catcher) to 220 pounds per hour. ^ A common
practice is to direct these fumes to the same collection devices
used for ingot furnace emissions. A dry inertial collector, such
as a. cyclone or a sand catcher, frequently precedes a baghouse in
order to remove the large abrasive particles, but high-efficiency
particulate collection equipment is necessary to remove the finer
(submicron) particulate.
SMELTING AND REFINING
Direct-fired (or open-flame) furnaces such as reverberatory
and rotary types will produce larger concentrations of zinc oxide
fume than indirect-fired furnaces such as crucibles and electric
22 BRASS AND BRONZE INDUSTRY
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induction furnaces will, other conditions being comparable. Since
the very hot and high-velocity combustion gases come in direct
contact with the metals in the charge, metal losses are high when
there is an appreciable proportion of zinc in the alloy. The direct-
fired type of furnace is often more difficult to hood effectively.
Except for the physical arrangements, however, the actual smelting
and refining that produce high-quality ingots are similar in both
direct-fired and indirect-fired furnaces.
A number of factors in furnace operation can affect the type
and quantity of emissions. Among these are the type of fuel used,
control of air-fuel ratios, control of temperatures, the order of
adding metals to the furnace, provision of proper slag cover, and
good housekeeping in the furnace area. These items will be dis-
cussed in typical chronological order.
Fuel used in the various furnaces can have important effects
on the types of emissions from the plants. Electric furnaces do
not add any objectionable emissions, and what is more important,
they do not have the sweeping effect of hot gases across the sur-
face of the melt. Indirectly heated furnaces also, avoid this
sweeping effect.
The choice of oil or gas as a. fuel is usually made on the basis of
lowest cost for a given heat content, but gas is often more trpuble-
free, both in minimizing pollution and in maintaining proper combus-
tion conditions. Plants are often equipped to burn either type of fuel
so as to take advantage of price fluctuations and seasonal availability.
When oil is used, very careful control of the air-fuel ratio is neces-
sary to reduce pollutants such as soot, smoke, and unburned fuel
particles to a. minimum.
Furnaces are often preheated and maintained hot before scrap
is added. The exhaust gases at this time are usually very clean
and are exhausted directly to the atmosphere. A common technique
is to alternate two furnaces, running only one at a time into a. single
dust collection device.
-Charging
The type and condition of the scrap raw material are factors
that may affect the content of emissions. Scrap that is oily, greasy,
or dirty may have these contaminants removed by preliminary treat-
ment, or the operations may be done directly in the main ingot
furnaces. In either case considerable smoke emissions are apt to
occur. With combustion there will be emissions of the normal pro-
ducts of combustion plus unburned hydrocarbons, fly ash, and dust
in the stack gases. When the scrap material being used has relatively
large proportions of low-volatility constituents such as zinc, metallic
oxide fume will be in the stack gases of the furnaces.
Air Pollutants Generated - Cause and Control 23
-------
During the charging cycle, emissions are also dependent upon
factors such as location of the charging doors, the percentage of
volatile alloy constituents (principally zinc), and upon whether the
entire charge is made at the beginning of the heat or at intervals
during the melting stage. Overhead charging doors in reverberatory
furnaces will permit large losses of hot gases, fly ash, and fume
into the plant when charges are loaded at intervals during the heat.
Effective hooding of overhead charge doors poses difficult problems
because of the necessity of providing access for loading equipment
into the space between the charge door and the hood. End and side
doors are not as vulnerable to the loss of furnace gases, especially
end doors that load the charge in the direction of the induced flow of
the furnace gases.
Some of the greatest air pollution problems occur during charg-
ing. It is physically difficult to place the entire charge into the
furnace at one time. Later charges are, therefore, added to molten
metal, and the combustible materials (and plain dirt) are emitted in
tremendous bursts that are almost impossible to burn completely or
even to contain within the capacity of the collection system.
During the charging of extremely oily scrap metal it is considered
good practice to turn off the burners. This reduces the total volume
of gases that must be collected during this short period of time.
Escape of pollutants during this period, however, still poses a
challenging problem for the industry. The volume and equipment
necessary to capture this escaping effluent would be extremely
large and expensive. One reverberatory furnace installation, using
top charging, is covered by a 12- by 24-foot hood with an air intake
capacity of nearly 40, 000 cubic feet per minute. 9 This is still
sometimes insufficient to capture all the emissions.
Melting
After material is charged, all doors and openings of the furnace
are closed. Burners are set to maximum efficiency for fastest
melt down and superheating of the molten metal. Supplemental
oxygen may be used at this time. A great amount of fumes may
occur whenever zinc is present or combustible contaminants are
present in the charge. The latter may include items such as grease,
oils, and rubber. Much of the combustible emissions may be con-
trolled by proper draft regulation and burner setting. A few
materials contain nearly as much oil as is normally fed to the burn-
ers, so that theoretically no additional fuel should be required. The
lack of uniformity in scrap, however, makes this control a difficult
art.
Refining
The terms "refining" and "smelting" are somewhat analogous
and interchangeable in that the raw materials are purified and impu-
rities are removed. Scrap normally contains 5 to 10 percent of wood,
24 BRASS AND BRONZE INDUSTRY
-------
dirt, and other nonmetallic contaminants that must be removed. In
a majority of the copper-based alloys certain elements such as iron,
manganese, silicon, and aluminum are normally considered contam-
inants and must be removed by refining.
Refining is that cycle of the heat in which impurities and other
constituents of the charge, present in excess of specifications, are
reduced or removed. Many different processes are employed to
bring the composition of the melted scrap within permissible limits.
Refining methods vary with the type of furnace, the type of alloy
being produced, the condition or availability of different types of
scrap in the charge, and the experience and opinions of the personnel
involved.
Refining is a chemical process of purification. These chemicals,
commonly termed fluxes, maybe gaseous, liquid, or solid. By far
the most extensively used gas for refining is compressed air (oxygen).
Blowing air into the molten bath of metal causes a. selective oxidation
of metals in accordance with their position in the electromotive series.
Iron, manganese, silicon, and aluminum are high in the series and
are, therefore, oxidized in preference to copper, tin, and other
metals. Part of the zinc is oxidized, but this is an unavoidable loss,
and below certain concentrations, the undesirable metals are oxidized
simultaneously.
The metal oxides, which are lighter than the molten metal, are
removed from the melt by entrapment in the slag covering and as
entrainment in the gases leaving the furnaces. The fumes and dust
in this hot airstream must be removed as an air pollutant. When
oxidation is purposely avoided, an inert gas such as nitrogen may be
used to remove entrained gases of solid impurities such as occluded
oxides. Bubbling of these inert gases in the molten metal can some-
times loosen foreign materials and bouyantly lift them to theisurface,
where they are removed.
A slag is usually formed on the surface of the melt. Part of this
is formed from nonmetallic material in the scrap, part is deliberately
added as a cover, and sometimes the slag also forms part of the
flux. Solid and liquid fluxes for refining can be either nonmetallic,
pure metals, or alloys. They may degasify, densify, fluidize, and
homogenize the alloy; deoxidize; act as hardener; or become part of
the alloy.
Fluxes as a whole do not contribute to air pollution, except in
releasing impurities that must be removed from the alloy in one way
or another. Flux covers, which are eventually skimmed off, have a
generally beneficial effect on the quality of stack emissions by
preventing excessive volatilization losses. Some of the more
common fluxes are broken glass, charcoal, borax, sand, limestone,
iron scale, soda ash, and caustic soda.
Air Pollutants Generated - Cause and Control 2 5
-------
The use of slag covers on the melt is generally desirable in all
types of furnaces. A thick layer is not desirable, since it will re-
duce heat transfer to the melt in direct-fired furnaces. Maintaining
the cover between 1/4 and 1/2 inch, depending on the type of alloy
and the furnace being used, is normally satisfactory. The composi-
tion of the cover 'will vary with the type of furnace, the scrap in the
charge, and the alloy being made. A heavy, inert, and tenacious
slag cover is, however, required in all cases.
It is the nature of refining to remove impurities from the molten
bath of metal. When these can be removed by the slag or flux cover-
ing, there •will be no air pollutants. When compressed air or gas is
blown beneath the molten bath of metal, impurities are entrained in
the effluent airstream. Most of these metal oxides are formed as a.
condensed fume and are submicron in size.
Alloying
Modification of the alloy during the heat by addition of virgin
metal or specialized scrap may lead to an increase in fume emission.
Having very nearly the required quantity of these alloy constituents
in the initial charge is preferable in order that the flux cover will
be formed early in the heat, protecting against excessive oxidation
and volatilization of the zinc. The problem of excessive formation
of fume naturally becomes greater as the percentage of volatile
constituents increases. Owing to its very low boiling point, zinc is
the most serious problem.
Pouring of Ingots
Physical methods of pouring the molten alloy into ingot molds
vary. The furnaces may be tapped directly to a moving, automati-
cally controlled mold line, the alloy sometimes filling one or more
molds at once and then being shut off while a new set of molds moves
into position on the endless conveyor. In other variations, the metal
is tapped from the furnace into a. ladle -which should have a slag
cover, especially for high-zinc alloys. The molten alloy is then
moved to a. mold line, which may be movable or stationary.
Metal oxide fumes are produced as the hot molten metal is
poured through the air, even over these short distances. Other
dusts and the like may be produced, depending upon the type of
linings or coverings associated with the mold as it is filled with hot
molten metal. Covering of the metal surface with ground charcoal is
one of the methods used to make "smooth-top" ingots. This char-
coal creates a shower of sparks, as in Figure 7. These emissions
are released into the plant environment at the vicinity of the tap and
the molds being filled. If there is no local exhaust system, fumes
may spread over a wide area of the plant. Hooding this movable
equipment can become exceedingly complex. The design of hoods,
air velocities, and associated ductwork has been treated at length
in various papers and books. 11 "13
26 BRASS AND BRONZE INDUSTRY
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Figure 7. Pouring of ingots.9
The control of pouring and melting temperatures is important.
The quality of the alloy will be affected by losses of the volatile
constituents. Too high a temperature during the melting and
refining cycle may result in having to add additional zinc because of
excessive fume loss. The "proper" pouring and melting temperature
will depend upon the alloy in question. There are disadvantages if
the pouring temperature is either too high (zinc losses) or too low
(freezeup). Exact control of temperature is not always an easy
task over the period of time required to empty the furnace, but
control within ±90° F is important.
Figure 8 indicates the melting, boiling, and pouring points of
some common copper-base alloys and their constituent metals. °
The boiling points of alloys containing zinc are approximately
proportionate to the zinc content. Alloys with 20 to 40 percent zinc
have boiling points around 2, 100° F and melting points of from
1, 700° F to 1, 900° F.
Air Pollutants Generated - Cause and Control
27
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Boiling point, • F Metal or alloy Meltino point, " F Pourlno t.mp., ° F
a ioo w-
2025
-Rid bran 65 cu. 15 In,
ManganiM
"G" Bron.aBB cu, 9Sn,
Aluminum in
Alymlnum aJToy
Figure 8. Boiling, pouring, and melting points of
metals and alloys.5
28
BRASS AND BRONZE INDUSTRY
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PRESENT CONTROL SYSTEMS
AVAILABILITY AND GENERAL USE
A number of basic types of control equipment are available for
removing particulates suspended in airstreams. They may be
classified into five general groups: settling chambers, cyclones or
centrifugal collectors, scrubbers, electrostatic precipitators,. and
baghouses. The first two types of equipment are not satisfactory
for submicron-sized particles. Wet scrubbers and precipitators have
not been particularly successful in the collection of zinc oxide fumes.4
The use of baghouse collectors has been the prime method to receive
general acceptance to this date by the brass and bronze ingot industry.
This does not imply that they are completely satisfactory or that
other devices are not occasionally employedi
Baghouses are filter devices with multiple tubular cloth bags
contained within roughly cubical airtight compartments. Figure 9
shows the configuration of a typical baghouse compartment. Fabrics
include cotton, glass fiber, wool, or synthetic fibers such as Orion*
and Dacron. * Baghouses are among the most efficient devices for
submicron particles. Manufacturers claim efficiencies up to 99.9
percent. Recent tests of operating units-"' showed efficiencies
generally between 95 and 99. 6 percent. Temperature limitations
of the filter fabrics may require cooling or dilution of the incoming
particle-laden airstream.
DESIGN OF CONTROL SYSTEMS
The typical dust collection system in the brass and bronze ingot
industry is not constructed with the overall operation but has been
added to existing furnaces. Often there are space limitations or
other problems in the physical layout. ~*> 9> 14, 15
A common practice is to operate furnaces as pairs, wherein one
furnace is heating in preparation for the charge while the second
furnace is concluding the previous refining operation and pouring
ingots. Rarely would both furnaces be in operation simultaneously.
This is because facilities for pouring and charging are shared between
the two furnaces. The air pollution control system is designed
around this type of operation to make the best use of the capacity
available for effectively cleaning the stack gases at optimum cost.
*Mention of company or product does not constitute endorsement by
the U.S. Department of Health, Education, and Welfare.
-------
CELL PLATE
Figure 9. Typical simple fabric filter baghouse design.
Because the furnaces are already in existence, with associated
exhaust stacks, the existing ductwork and refractory-lined flues
are often used in the new construction. These flues first offer some
degree of cooling and, at least in some instances, offer a collection
of coarse dust. The operation of fabric filters requires that all
oxidizable or combustible material be provided with sufficient air
10
BRASS AND BRONZE INDUSTRY
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to oxidize the furnace effluent and eliminate the possibility of burning
within the baghouse. These hot, refractory-lined flues are ideal for
the introduction of sufficient air to complete all combustion.
When the temperature of the exhaust gases is reduced to a
certain point, they may be contained in metal ductwork to take
advantage of radiation cooling. The initial cooling is often accom-
plished by means of water sprays. This reduces the temperature
and volume of the gases to be filtered but adds moisture that must
be carefully controlled to avoid reaching the dew point at any time
before final emission of these gases. Figure 10 shows an all-dry
system that uses a. water-jacketed flue.
MAIN BRICK
— STACK
REVERBERATORY
FURNACE
AUTOMATIC DRAFT CONTROL
Figure 10. Sketch of small baghouse for zinc fume (Allen et al., 1952).
It appears to be common practice to install two similar dust
collection units for a. given situation at a plant rather than to
install one single large unit. This not only offers some degree of
emergency capacity but also offers flexibility in operation. Plants
using a blast furnace or cupola normally tie the fume collection
ductwork into a common system with the refining furnace emissions.
The necessity of locating baghouses at some distance from the
furnaces may be considered an advantage because of the radiation
Present Control Systems
31
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cooling that results, but at times this can be detrimental. Heat
dissipation is inconsistent between summer and winter conditions,
and condensation may result at the baghouse during a sudden cold
snap. As the gases reach the dew point the dust becomes wet and
forms mud in the hoppers or on the bags; resistance to airflow
increases so rapidly that the baghouse is no longer functional.
Furnace burners are sometimes left on to maintain heat in the
system and thereby prevent condensation.
Following the water spray cooling there is usually a variable
length of ductwork, depending upon the plant layout, before a section
of U-tube or hairpin coolers. These coolers, as in Figure 11, may
be bypassed during periods when the operation or weather is
drastically changed and less cooling is required.
Figure 11. A dust collecting system for secondary smelting and melting plant.
(Courtesy H. Kfomer and Company)
In spite of all the methods used for cooling before the baghouse
itself, it has been found generally necessary to provide an emer-
gency bypass at the inlet to the baghouse so that fresh air may be
bled into the exhaust gases. The fan volume is roughly constant,
and hence, if the dilution air damper opens, it means lower draft at
the furnace. This is a disadvantage to proper capture of fumes but
is sometimes necessary to avoid burning the bags during an emer-
gency or unusual period of high gas temperature.
32
BRASS AND BRONZE INDUSTRY
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BAGHOUSE OPERATION
While baghouses have been found to be the most successful
device for collecting large quantities of zinc oxide, there has been
no universal acceptance of a particular filter fabric. These fabrics
must be able to withstand fairly high temperatures in spite of the
dilution and precooling of gases. They must also withstand
considerable physical abuse and vibration.
The filtration efficiency of either felt or woven fabrics is not
based on direct entrapment, since the space between fibers is larger
than the diameter of particles involved. The cake of collected dust
on the fabric develops very rapidly, and high collection efficiency is
usually attained soon after installation. The intermittent removal
of the filter cake from the fabric is a prime consideration in bag-
house design. Zinc oxide has a tendency to cling to fabrics, but
mechanical techniques for dislodging the filter cake have been used
successfully.
The use of glass fabric in baghouses allows higher temperature
operation (55*0° F continuous) than the use of synthetic organic fabrics.
The inherently low mechanical strength of glass fabric requires
cleaning methods of a lower intensity than that of the mechanical
shaking methods used with the synthetics, which are stronger. This
basic difference has resulted in wide differences of opinion among
various operators over which approach is "best. " Good systems
are based on both approaches, but the majority of the baghouses
reported in operation are fitted with synthetic organic fabric and
mechanical shakers.
Baghouses are generally considered satisfactory for control-
ling zinc oxide fumes provided they are not overloaded. Normal
pressure drop ranges from 2 to 6 inches of water. Filter ratios of
2.0 to 2.7 cfm per square foot of filter area is the approximate
range established in the industry. 9, 16 The lower ratio is more
appropriate with heavy dust loadings and continuous-duty service.
Variations of from 1. 7 to 3. 5 cfm per square foot have been reported
by BBII members, owing partially to the fabrics involved and
partially to the differences of opinion and experience from one
operator to the next.
The life of the bags can be extended by careful attention to the
cleaning schedules and by use of various types of automatic clean-
ing equipment. Since the rate of buildup of particulate matter on the
filter surface varies considerably (this being due to the variations
of the process, differences in alloys, furnaces, 'operation, and so
on), automatic systems controlled by pressure-limiting devices
rather than by cleaning at fixed intervals of time have possible
advantages.
Present Control Systems 33
-------
The baghouse should have a sufficient number of compartments
so that one compartment can be bypassed while the others continue
to operate and thus permit replacement of broken bags or allow for
unusual cleaning requirements. The use of four compartments
normally satisfies this requirement. The temperature at which flue
gases enter the baghouse affects the life of the bag severely. Maxi-
mum temperatures recommended by the Industrial Gas Cleaning
Institute for several of the more commonly used fabrics are
shown in the following tabulation.
Filter fabric
Cotton
Dacron, heat-set
Glass fiber
Orion, heat-set
Wool, treated
Maximum continuous
operating temperature, °F
180
275
550
260
200
The various techniques for gas cooling add more or less to the
total •weight of exhaust gases. Radiation cooling adds none, and
water sprays, a moderate amount, but air dilution causes a major
increase in total air handling, especially when it reduces gas temper-
atures to less than 300° F. A typical gas-cleaning system delivers1
a nearly constant air volume at the fan regardless of the temperature.
The draft at the furnace, since it is at the far end of the system from
the fan, is affected if there are significant changes in the gas-cooling
system.
The original purpose of the process is, of course, to produce
high-quality ingots. This sometimes requires a variation in temper-
atures and quantity of these exhaust gases. As mentioned previously,
the concentration of dust emitted from the furnace varies considerably.
During the refining step, in which compressed air is being blown
beneath the molten bath, a large change occurs both in the volume of
gases and the concentration of fumes in those gases. During periods
•when scrap metal is added to the furnace, large amounts of fumes are
generated. Since the capacity of the collection system maybe inade-
quate for extremely large volumes of fumes,_ dust laden gases may
escape through furnace doors or other openings in the furnace into the
plant and, eventually, into the atmosphere. The entire refining cycle
is complex. During some periods there are very few emissions,
relatively cooler temperatures, and a minimum volume of gases.
Conversely, during other periods the emissions are very great, the
volume of gases is high, and the temperatures are maximum. Insofar
as possible, these variations should be incorporated within the design
of the collection system so that plant operations maybe continued at
full capacity under any conditions.
INSTRUMENTATION
Standard baghouse instrumentation design in zinc oxide applica-
tions is not strikingly unusual, but certain safeguards are essential
34 BRASS AND BRONZE INDUSTRY
-------
if satisfactory operation is to be maintained for continued periods of
time. A typical system would usually allow fresh air to be bled into
the exhaust gases leaving the furnace in order to provide for complete
combustion. This is not normally controlled except on the basis of
the draft maintained at that point. The hot gases from the furnace
are frequently cooled by water sprays activated in proportion to the
temperature of the gases. Standard recorders are employed, and a.
series of cam-actuated switches turn on one or more series of sprays.
Either in place of, or in addition to, the spray chambers, there may be
coolers using metal fins, water jackets, or a simple length of duct-
work. Each of the aforementioned devices is used for primary
cooling of the extremely hot gases to below 1, 000° F. Final cooling
is usually accomplished by means of U-tube radiation coolers. These
are simply hairpin lengths of pipe installed vertically and exposing a
large duct surface area. These tubes (Figure 11) are usually about
30 feet tall and may be bypassed by hand setting various gates or by
automatic instrumentation. Hand adjustment is the common practice.
These allow for major changes in operation or •weather but do not
compensate for quick changes. Just upstream of the baghouse is an
atmospheric damper, controlled automatically by a standard tem-
perature sensor so that it will gradually open if the temperature
exceeds a-'preset limit. If the temperature of the gases entering the
baghouse is still greater than can be withstood by the bag material,
there is usually either an emergency shutdown device that will cut off
the fans completely or a means for bypassing the hot gases around
the baghouse.
In addition to the automatic equipment and controls the use of
maximum-indicating thermometers in each compartment of the bag-
house has been found desirable. An operator can thereby check the
temperature extremes in any section over a period of time such as
one shift or 1 day. This provides important information in regard
to maintenance of the bags and their subsequent replacement.
^Differential pressure gages are commonly used across each
compartment of the filter. Wide differences in pressure drop between
compartments is an indication of operational difficulty. Static pres-
sure of differential pressure gages placed at intervals in the dust /
system can pinpoint duct plugging and save time in system maintenance.
MAINTENANCE
Upon installation of air pollution control equipment, an effective
program of maintenance of the entire dust collection system should
be instituted without delay. Provisions should be made for spotting
broken bags in the baghouse at once. Mechanical equipment and
various automatic and manual control devices in this, as in any other
system, should be checked frequently by maintenance personnel.
The installation of instrumentation and relatively automatic
equipment does not guarantee continuous or satisfactory operation.
Present Control Systems 35
-------
Maintenance of an air pollution control system is a continuous
(perhaps even full-time) job. Even the best "automatic" equipment
requires regular maintenance. In addition to providing satisfactory
operation, good maintenance has frequently been found to save money
in the long run.
Permanent records are desirable for evaluating changes in
conditions, unusually high temperatures, or any other problems that
develop. When the maintenance operator is not familiar •with
differential pressure gages or some basic operations of the temper-
ature controls, the entire system will soon be degraded. This is
usually reflected in insufficient gas volume for proper operation of
the furnaces, as in Figure 12. This forces the plant either to operate
with fume losses or to curtail production.
Figure 12. Fume loss at furnace doors resulting from insufficient
gas volume in dust collection system.
Owing to the flammability of unburned zinc or hydrocarbons
associated -with the scrap metal, care must be continually empha-
sized to prevent fires within the baghouse. Bridging of the dust in
hoppers is particularly serious, for the bulk of dust insulates the
exothermic reaction, and an entire section of bags can be lost in a
fire.
Maintaining duct velocities within 2, 500 to 3, 000 feet per minute
(fpm) is desirable. This is often not seen in practice, some velo-
cities being reportedly down to 1, 500 fpm on occasion. These low
velocities cause buildups of dust in the duct, overheating if the rad-
iant heat loss is needed to dissipate heat and reduce system gas
volume, leading to poor system operation.
COSTS
The capital costs of air pollution control systems in the brass-
and bronze-smelting industry are frequently higher than a casual
36 BRASS AND BRONZE INDUSTRY
-------
appraisal might indicate. Any time a system must be installed in
an existing plant there will be extra costs to "fit it in" without
major structural changes or interruption of the process. These
factors can increase costs, in specific instances, far beyond the cost
of the same capacity system installed as part of a new plant.
Data available on air pollution control costs at brass and bronze
smelters indicate a broad range of installation costs. Two published
figures are $3. 50 per cfm7 and $6. 25 per cfm ^ for systems that
accomplish the same basic purpose (1969 dollars). Data from BBII
member companies suggest that a cost of $5. 00 per cfm might be
"typical" for an installed system, the baghouse itself representing
about 40 percent of the total cost.
The costs of maintenance and operation of an air pollution
control system are a very real consideration in the industry. Costs
were supplied by four smelters: $2.00, $0.90, $1.50, and $1.73
per ton of ingots produced. The accountants for these companies
were in accord on the procedures used in this calculation and, as
nearly as possible, the costs are reported on a. comparable basis.
The costs include operations and maintenance, personnel salaries,
maintenance supplies, electricity, water, gas, the fringe benefits
applicable to salaries, and credits for value of byproduct material.
The amortization of the capital cost of the system is not included.
EMISSIONS DATA - NAPCA TESTS
The most nearly complete test data available for brass- and
bronze-smelting operations were collected by the National Air
Pollution Control Administration, Abatement Program, Engineering
Section, during 1968. These tests were conducted with the coopera-
tion of BBII firms for the specific purpose of providing data for this
report. Test results are given in Tables 5 through 12.
Test methods are outlined in the Appendix. The tests were
meticulously conducted by a. large crew of trained personnel. Varia-
tions and occasional anomalies in these results emphasize the
difficulty of collecting "representative" data from a process as highly
variable as secondary smelting. The test-by-test data and opera-
tional observations are noted as follows.
Test A
A heat of red brass 85-5-5-5 (copper, zinc, tin, lead) was
made in a 17-1/2-ton-rated rotary furnace. A total of 33, 334
pounds of scrap and 500 pounds of flux were charged to the furnace
during the 6. 5-hour charging period. Air blowing, slagging, and
heating were performed during the 6. 8-hour refining cycle. The
pouring cycle lasted 1. 3 hours.
During.this test, only the 17-1/2-ton rotary furnace was operat-
ing. Inlet samples were collected during each period. A single
Present Control Systems 37
-------
sample was taken at the baghouse outlet over the entire heat.
The exhaust system captured an estimated 90 to 95 percent of
the particulate generated at the furnace.
Table 5. ROTARY FURNACE PARTICULATE EMISSIONS - TEST A
Cycle
Chargee
Refine
Pour
Total
Length, hr
6.50
6.80
1.28
14.58
Emissions, furaacea Baghouse outletb
Ib/hr
30.05
42.75
9.54
Cycle total, Ib
195
291
12
498
Ib/hr
1.78
Total, Ib
25.9
aFurnace emission factor: 29.9 Ib/ton.
bCollection efficiency: 94.8 percent.
cTotal charge: 33,334 Ib. Alloy produced: BBII Alloy No. 4A; 85-5-5-5.
Test B
At the same system as Test A, three 1-hour samples •were
collected at the baghouse exit. During collection of the first two
samples, the 17-1/2-ton rotary was being charged, and the cupola
and a 7-1/2-ton rotary furnace were being preheated. During the
third test the 17-1/2-ton rotary "was refining, the 7-1/2-ton rotary
•was charging, and the cupola was in full operation.
The air pollution control system controlled the emissions from
five rotary furnaces and a cupola. The gases from all five produc-'
tion units pass through a common spray chamber, past an air-bleed
damper, into an Orion fabric baghouse, a 150-horsepower fan, and
out a stack. The baghouse has a rated capacity of 43, 000 cfm at 220° '.
There are 20,866 square feet of filter area in this shaker-type, six-
compartment baghouse. The design filter ratio during shaking is
2.46/1.
Measured gas temperatures at the baghouse varied between
140° F and 190° F.. Pressure drop at the baghouse varied from 3-1/2
to 4-1/2 inches of water. Measured stack gas volume was 34, 000
scfm (70° F).
Table 6. ATMOSPHERIC PARTICULATE
EMISSIONS FROM BAGHOUSE
ON ROTARY FURNACES - TEST B
Sample
B-l
B-2
B-3
Baghouse outlet
gr/scf
0.018
0.011
0.021
Ib/hr
5.18
3.32
6.39
38
BRASS AND BRONZE INDUSTRY
-------
Test C
A heat of 85-5-5-5 red brass was made in a 100-ton reverbera-
tory furnace. A total of 105, 000 pounds of metal was charged to the
furnace over a period of 6.7 hours. Oxygen was supplied to the
burners for 5. 3 of these hours to increase the melting rate. During
a 9. 3-hour refining period there was intermittent air blowing, and
500 pounds of fluxes were added. Pouring took 3. 5 hours.
This air pollution control system serves three 100-ton reverber-
atory furnaces. The gases pass through a common spray chamber
and then through a set of U-tube radiation coolers. From this point,
the 450° F to 650° F gases are mixed with bleed-in air, go through
the baghouse and a. 75-horsepower fan, and pass to the stack. The
16-compartment shaker-type baghouse is fitted with heat-set Orion
bags. The total filter area is 7, 360 square feet and the rated capac-
ity is 19,000 cfm at 220° F. The design filter ratio, with one com-
partment out for cleaning, is 2.75/1.
Measured gas temperature at the baghouse inlet cycled between
200° F and 220° F. The measured gas volume averaged 15, 000 scfm
(70° F). Baghouse pressure drop varied from 4 to 5 inches of water.
One inlet sample was taken during each of these three furnace
periods: charging, refining, and pouring. A continuous baghouse
outlet sample was taken over the entire heat.
Table 7. REVERBERATORY FURNACE PARTICULATE EMISSIONS - TEST C
Cycle
Charge0
Refine
Pour
Total
Length, hr
6.73
9.30
3.53
19.56
Emissions, furnace3
Ib/hr
194.2
159.3
12.8
Cycle total, Ib
1,308
1,482
45
2,835
Baghouse outlet b
Ib/hr
3.32
Total, Ib
64.8
aFurnace emission factor: 53.7 Ib/ton.
bCollection efficiency: 97.7 percent.
°Total charge: 105,500 Ib. Alloy produced: BBII Alloy No. 4A; 85-5-5-5.
Test D
A set of two 1-hour samples was taken at the stack of the system
described in Test C. Two reverberatory furnaces were operating
during these tests. Both furnaces were melting during the first
test and both were charging during the second test.
Present Control Systems
39
-------
Table 8. ATMOSPHERIC PARTICULATE
EMISSIONS FROM BAGHOUSE
ON REVERBERATORY FURNACES - TEST D
Sample
D-l
D-3
Baghouse outlet
gr/scf
0.025
0.031
Ib/hr
5.13
6.37
Test E
At the system described in Test A, samples were taken while
only the cupola -was in operation. The cupola was charging at 20-
minute intervals at the rate of 5, 900 pounds per hour, including
coke and flux.
Gas temperature at the baghouse was 145° F to 200C
volume was 44, 000 scfm. The filter ratio was 2.11/1.
F and the
Table 9. CUPOLA PARTICULATE EMISSIONS - TEST Ea
Sample
E-l
E-2
E-3
Average
Inlet
gr/scf
0.68
0.68
Ib/hr
216
216
Outlet
gr/scf
0.027
0.030
0.020
0.026
Ib/hr
8.38
9.25
6.38
8.00
aCharging rate: 5900 Ib/hr. Collection efficiency:
Furnace emission factor: 73.2 Ib/ton.
6.4 percent.
Test F
A reverberatory furnace rated at 60 tons was tested over a full
cycle, with three baghouse inlet samples (charge, refine, pour)
and a single baghouse outlet sample.
Furnace gases pass to a spray chamber and then to U-tube
coolers. Air-bleed dampers are located at the U-tubes. The
baghouse, with a rated capacity of 22, 000 cfm at 180° F, has
5, 940 square feet of Dacron fabric. The design filter ratio is
3. 87/1. A 75-horsepower fan is used in the system.
Measured stack gas volume was 18, 000 scfm (70° F) during
this testing period. Capture efficiency is estimated at 80 to 85
percent. '
40
BRASS AND BRONZE INDUSTRY
-------
Table 10. REVERBERATORY FURNACE PARTICULATE EMISSIONS - TEST F
Cycle
Charge0
Refine
Pour
Total
Length, hr
8.5
10.3
3.3
22.1
Emissions, furnacea
Ib/hr
500.1
681.1
8.5
Cycle total, Ib
4,250.8
7,015.3
28.1
11,294.2
Baghouse outlet15
Ib/hr
2.17
Total, Ib
47.9
aFurnace emission factor: 156.9 Ib/ton.
^Collection efficiency: 99.6 percent.
cTotal charge: 144,000 Ib. Alloy produced: BBII Alloy No. 5A; 81-3-7-9.
One of three 4-ton-per-hour rotary furnaces in this system was
tested over a full cycle. The air pollution control system consists
of a spray chamber, U-tube coolers with air-bleed dampers, a
Dacron fabric baghouse, 60-horsepower fan, and stack. The
shaker-type baghouse has 9, 700 square feet of Dacron fabric bags.
The rated capacity is 24, 800 cfm at 150" F. for a filter ratio of
2.56/1.
The exhaust system capture of pollutants was about 80 to 85
percent during this test. This should be considered when the
calculated emission factor is evaluated.
Table 11. ROTARY FURNACE PARTICULATE EMISSIONS - TEST G
Cycle
Charge b
Refine
Pour
Total
Length, hr
6.1
1.1
7.2
Emissions, furnace a
Ib/hr
c
101.2
6.9
Cycle total, Ib
617.3
7.6
624.9
Baghouse outlet
Ib/hr
d
Total, Ib
d
aFurnace emission factor: 147 Ib/ton.
bTotal charge: 8,500 Ibs. Alloy produced: BBII Alloy No. 6C; 63-1-1-35.
°Charge and refine run as one test.
^Collection efficiency: No data available.
Tests H and I
A cupola and two reverberatory furnaces were serviced by a
single air pollution control system at this location. Only the cupola
was in operation during these tests. The charge rate was about
4, 200 pounds per hour, including coke and flux.
Present Control Systems
41
-------
This control system had originally been designed to service the
two reverberatory furnaces. Spray chambers provided the initial
cooling, followed by U-tube coolers. A 75-horsepower fan drew gases
through a shaker-type baghouse with 10, 560 square feet of Dacron
fabric. When the cupola emissions were added to the system, the
discharge gases from a. sand catcher were tied into the system between
the spray chamber and the U-tube coolers. A booster blower was
installed in this ductwork branch to ensure adequate suction at the
cupola. In testing this installation the space limitations precluded
sampling at the cupola outlet, and so samples were taken at the outlet
of the sand catcher.
The test data showed that stack volume was twice the inlet
volume for Test H (auxiliary blower on) and three times the inlet
volume for Test I (auxiliary blower off). These major discrepancies
are attributed to leaks in the baghouse structure. With leakage vol-
umes of this magnitude it can be assumed that particulate matter
•would be mixing "with the stack gases downstream of the bags. This
would lower the apparent efficiency of the baghouse, and may explain
the low reported efficiencies.
Table 12. BLAST FURNACE PARTICULATE EMISSIONS -
TESTS H AND I
Charging rate
Emission rate
Baghouse outlet
Collection efficiency
Furnace emission factor
Test H
4,200 lb/hr
42.3 lb/hr
6.5 lb/hr"
84.6 %a
20.1 lb/tonb
Test I
4,200 lb/hr
35.1 lb/hr
9.3 lb/hra
73.5 %a
16.8 Ib/tonb
aHigh lb/hr and low efficiency data probably due to baghouse leaks
allowing particulates to enter gas stream.
''Not actual furnace emissions - samples taken after preliminary
collector due to space limitations.
Detailed results of these tests can be found in the Appendices. ^
few spot checks for SO2, NOz, IH^S, hydrocarbons, and halogens
indicate that all these gases exist in concentrations of below 1 ppm.
OTHER DATA
Although these test data are the most nearly complete available,
other useful sources of emission information are available. Most
of this information comes from BBII member companies and repre-
sents actual conditions in the industry as of 1968.
The analysis of typical collected dust is shown in Table 4. 9
Table 13 summarizes information from questionnaires completed by
BBII member companies. Table 14 contains some of the available
information on existing baghousesr" Zinc oxide ranges from 60 to
42 BRASS AND BRONZE INDUSTRY
-------
Table 18. AIR POLLUTION CONTROL EQUIPMENT IN USE IN THE INDUSTRY
Furnace type
Reverbetatory
Rotary
EleOtrtO
Crucible
Sweat
Gupela
Wire burning
Retary dryer
teei«e*at©r
Raw material eoneeatrater
Slag ftimaee
O»«!esi^Rated
Number
Q
6
4
7
\i
8
8
1
3
S
g
1
1
\*
§
1
8
1
8
4
1
i
3
\>
4
S
S
0
a
0
1
1
4
1
4
i
i
i
l
i
i
8
1
1
1
a
Approximate capacity, tons
80
75
70
60
SO
§0
SE
18
18
85
IS
10
10
5
4
4
S.7
8-1/2
t>
8 1?)
4
S
1/8
1/8
1
8/4
I/I
0.4
s/s
1/4
600 lb
100 lb
-
.
-
-
-
-
-
.
-
85
5
8
1
Control equipment
BagUouse
Bughouse
None
Bagtvouse
None
Baghouse
None
Baghouse
None
Baghouse
None
Baghouse
None
Baghouse
Baghouse
None
Baghouss
None
Baghouse
None
Baghouse
Baghouse
Baghouse
Scrubber
None
None
None
None
None
None
None
None
None
Afterburner
and baghouse
Bag-house
None
Wet collector
Afterburner
chamber
None
Afterburner
Cyclone
None
Baghouse
None
None
None
Present Control
43
-------
Table 14. BAGHOUSE INFORMATION SUMMARY - BRASS AND BRONZE INGOT INSTITUTE
g
03
W
O
N
H
3
a
en
Size of baghouse, cfm
2 units -24, 000 ea (design)
18,000 (actual)
3 units -13, 000 ea (design)
10,000 cmf (design)
27,500 (design)
18,000 (actual)
30,000 (design)
29.000 (actual)
Square-filter type
26.000 (design)
Multiple-bag type
Custom-designed
12.500 cfm/chamber
(No. of chambers not
reported)
30,000 (design and actual)
50.000 (design and actual)
No. of bags -
diameter, in.
1,944- 6
2,268 - 6
100 - 15
324 - 8
528 - 8
320 - 5
900 - 8
400 - 10
1,500- 6
416 - 18
1.200 - 5
800 - 8
Bag
material
Orion and
Dacron
Dacron
Glass
Orion and
Dacron
Orion and
Dacron
Orion
Orion
Orion
Orion
Wool
Orion
Orion
Type and size of
furnaces vented
to the baghouse
2 Rev-60 tons/ht ea
2 Rot-2 tons/ht ea
4 Elec-l@4 tons/ht
3(81/2 ton/ht
2 Rev-60 tons/ht ea
2 Rot-4 tons/ht ea
1 Cupola
1 Radiator sweater
4 Rev-60 tons/ht ea
3 Rot-4 tons/ht ea
No flow diagram pro-
vided; equipment
layout not
ascertainable
3 Rev-30-75 tons/ht
ea
1 Rot-10 tons/ht
Cupola
2 Rev-80 tons/ht ea
5 Rot-7-1/2-35
tons/ht ea
No flow diagram pro-
vided; layout of
equipment not
ascertainable
3 Rev-2-75tons/htea
3 Rot-2. 7 tons/ht ea
3 Crucible-0.25
tons/ht ea
1 eleo-3 tons/ht
1 Cupola-no tonnage
reported
3 Rev- 3-30 tons/ht ea'
1 - 12 tons/ht ea
1 Slug-15-25 tons/ht
ea
Material collected in baghouses
Ib/ton
charged
58
60
60a
55
NR
NR
NR
Ib/ton
produced
67
68
88a
NR
NR
NR
NR
% ZnO
63
78
72a
58
65
55
NR
% PbO
8
7.5
8a
3
5 to 6
NR
NR
Frequency
of bag
replacement
18 months
10 to 15
months
4 months
6 months
12 months
12 months
6 months
51 months
12 months
aNot stipulated if these figures are total figures for the three units.
-------
95 percent of the material collected, and lead oxide normally ranges
from 6 to 8 percent. Apparently, about 3 percent of the total mate-
rial charged to the furnaces is eventually collected in the baghouses
in operation. Tables 15 and 16 are not directly applicable, because
they refer to the brass and bronze foundry industry, but these give
some indication of the extreme variations that might be expected
from various ingot compositions and operations. Table 17 indicates
that some of the wet scrubber control devices serving zinc oxide
fumes are not particularly efficient.
During the refining process it has been indicated that 160 cfm of
compressed air (typical for 50-ton reverberatory furnace) will
volatilize and oxidize up to 750 pounds of zinc per hour in the metal
bath. 7 This "blowing" may continue from a few minutes to several
hours during a. 24-hour heat, depending upon the impurities present
and the alloy being produced. Based upon the total volume of gases
expected from this furnace, at baghouse conditions, this could
result in a ZnO concentration of roughly 20 grains per cubic foot
at the furnace.
Foundry operation does not use the refining step ( and several
other factors are different), but the loss of zinc oxide fume at melt-
ing and pouring temperatures for brass is related. It has been
indicated that particulate emission, for the whole melting cycle,
varied from 0. 05 grain per cubic foot for a low-frequency induction
furnace to 1.3 for a. 300-pound oil-fired tilting crucible. During the
last stages of the heating cycle, values were as high as 4. 1 for an
oil-fired tilting crucible. 18
Regardless of the total gas flow, temperatures, and variations
with alloy, time, and so forth, the daily discharge of emissions from
a 100, 000-pound reverberatory brass ingot furnace is about 3, 000 to
4, 000 pounds. °> ^ Some material will exist at rather small concen-
trations along with the very large concentrations that may occur from
time to time.
Present Control Systems , 45
-------
Table 15. DUST AND FUME DISCHARGE FROM BRASS-MELTING FURNACES8
Type of furnace
Rotary
Rotary
Rotary
Electric induction
Electric induction
Electric induction
Cylindrical reverberatory
Cylindrical reverberatory
Cylindrical reverberatory
Cylindrical reverberatory
Crucible
Crucible
Crucible
Composition of alloy, %
Cu
85
76
85
60
71
71
87
77
80
80
65
60
77
Zn
5
14.7
5
38
28
28
4
.
-
2
35
37
12
Pb
5
4.7
5
2
.
.
0
18
13
10
1.5
6
Sn
5
3.4
5
.
1
1
8.4
5
7
8
.
0.5
3
Other
_
0.67 Fe
.
.
_
,
0.6
.
.
.
.
1
2
Type of
control
None
None
Slag cover
None
None
None
None
None
Slag cover
None
None
None
Slag cover
Fuel
Oil
Oil
Oil
Electric
Electric
Electric
Oil
Oil
Oil
Oil
Gas
Gas
Gas
Pouring
temperature, °F
No data
No data
No data
No data
No data
No data
No data
2,100
2,100
1,900 to 2,100
2,100
1,800
No data
Process wt,
Ib/hr
1,104
3,607
1,165
1,530
1,600
1,500
273
1,267
1,500
1,250
470
108
500
emission,
Ib/hr
22.5
25
2.73
3.47
0.77
0.54
2-42
26.1
22.2
10.9
8.67
0.05
0.822
Cd
Z
e
w
w
o
N
H
a
-------
Table 16. BRASS-MELTING FURNACE AND BAGHOUSE COLLECTOR DATA8
Case
Furnace data:
Type of furnace
Fuel used
Metal melted
Composition of metal melted, %
Copper
Zinc
Tin
Lead
Other
Melting rate, Ib/hr
Pouring temperature, °F
Slag cover thickness, in.
Slag cover material
Baghouse collector data:
Volume of gases, cfm
Type of baghouse
Filter material
Filter area, ft2
Filter velocity, fpm
Inlet fume emission rate, Ib/hr
Outlet fume emission rate, Ib/hr
Collection efficiency, %
A
Crucible
Gas
lYellow brass
70.6
24.8
0.5
3.3
0.8
388
2,160
1/2
Glass
9,500
Sectional
tubular
Orion
3,836
2.47
2.55
0.16
93.7
B
Crucible
Gas
Red brass
85.9
3.8
4.6
4.4
1.3
343
2,350
1/2
Glass
9,700
Sectional
tubular
Orion
3,836
2.53
1.08
0.04
96-2
C
Low-frequency induction
Electric
Red brass
82.9
3.5
4.6
8.4
0.6
1,600
2,300
3/4
Charcoal
1,140
Sectional tubular
Orion
400
2.85
2.2a
0.086
96.0
alncludes pouring and charging operations.
Table 17. EFFICIENCIES OF WET SCRUBBER CONTROL DEVICES
SERVING BRASS-MELTING FURNACES8
Type of
scrubber
Venturi with
wet cyclone
Dynamic wet
Dynamic wet
Water
rate,
gpm
7.6
20.0
50.0
Flue gas
volume,
scfm
860
770
1,870
Particulate
matter,
gr/scf
In
2.71
0-905
1.76
Out
0.704
0-367
0.598
Total dust,
Ib/hr
In Out
19.95 7.04
5.97 3.00
28.2 13.2
Efficiency,
%
65
50
53
Present Control Systems
47
-------
REFERENCES
1. Ingot Brass and Bronze BBII, Chicago, Illinois, March I960.
2. Copper Scrap Consumers, Mineral Industry Surveys, U. S.
Department of the Interior, Bureau of Mines (Monthly).
3. Bulletin NF-66 National Association of Secondary Material
Industries, 330 Madison Avenue, New York, N. Y.
4. Papers presented at NASMI'S First Air Pollution Control Work-
shop, Pittsburgh, Pa. June 1967. Air Pollution Control in the
Secondary Metal Industry. Pub. as a membership service by
National Association of Secondary Material Industries, Inc. ,
330 Madison Avenue, New York, N. Y.
5. Spendlove, Max J. Methods for Producing Secondary Copper.
United States Department of the Interior, Bureau of Mines.
1C Bureau of Mines Information Circular 8002. 1961
6. Allen, Glenn L. , Viets, Floyd H. , and McCabe, Louis C. ]
Control of Metallurgical and Mineral Dusts and Fumes in Los ,
Angeles County, Calif. United States Department of the Interior.
April 1952. Bureau of Mines Information Circular 7627.
7. Schwartz, Harry E. , H. Kramer and Company; Kalian, Leo E. ;
and Stein, Arnold, Los Angeles County Air Pollution Control
District. Controlling Atmospheric Contaminants in the Smelting
and Refining of Copper-Base Alloys. J. APCA V5 Nl May 1955.
8. Air Pollution Engineering Manual, Air Pollution Control District,
County of Los Angeles. Public Health Service Publication No.
999-AP-40, pp. 270-284, 1967.
9. Questionnaire survey and personal interviews; BBII member com-
panies, 1967-8.
10. National Air Pollution Control Administration, Source Testing
Unit, Unpublished data, 1968.
11. Hemeon, W. C. L. Plant and Process Ventilation, The Industrial
Press, N. Y.,1963.
12. DallaValle, J.M. Exhaust Hoods, The Industrial Press, New
York, 1952.
49
-------
13. Industrial Ventilation Manual, American Conference of Govern-
mental Industrial Hygienists, Cincinnati, Ohio, 1967.
14. Kepner, H.F., Romanoff, Wm. , and Thieme, C. O. , Recovery
of Dust and Oxide at a Secondary Metal Brass Smelter.
15. Landis, T.A. The Application of Bag Filters to Metallic Fumes
in a Non-Ferrous Smelting Plant. April 1956.
16. The Fuller Engineer V17 Nl.
17. Industrial Gas Cleaning Institute, Rye, New York.
18. Cleary, G.J.M. and Palmer, D. G. , Particulate Emissions
from Brass Foundries, Australasian Eng. (Sydney) 55-6, 58
(August, 1967).
5 ° BRASS AND BRONZE INDUSTRY
-------
APPENDICES
A. NAPCA SAMPLING PROCEDURES
B. NAPCA TEST DATA
C. MEMBERS OF BRASS AND BRONZE INGOT INSTITUTE
51
-------
APPENDIX A.
NAPCA SAMPLING PROCEDURE
Methods and Equipment
To conduct the particulate and gas sampling, an initial velocity
traverse, spot checks for moisture content, and continuous stack
temperature values were needed at each sampling site. The initial
velocity traverse was obtained by measuring the pressure drop
across an S-type pitot tube with an inclined/vertical manometer as
the pitot tube traversed two mutually perpendicular stack diameters.
The manometer •was housed in the particulate meter box and •was
connected to the pitot tube by a flexible umbilical cord. Moisture
content of the effluent "was obtained by determining the weight of
water that was adsorbed by a preweighed silica gel tube •when a
measured amount of stack gas was passed through the tube. The
moisture sample was taken from the stack with a gas probe, from
which it passed directly into the silica gel tube. The sample was
then conveyed through an umbilical cord into the gas meter box,
where it was forced through a dry gas meter by a vacuum pump to
determine the sample volume. Continuous stack temperatures were
taken with a bimetallic thermometer with a temperature range of 0° F
to 600° F.
Particulate sampling was carried out with the particulate train,
which consists of a probe, the particulate sample box, an umbilical
cord, and the particulate meter box (see Figure A-l). The sample
was taken from the stack effluent through the probe nozzle, then
through the heated probe and into the particulate sample box. In
the sample box, the large particulates (> 5 microns) were collected
in a glass cyclone while the smaller particulates (< 5 microns) were
collected on a glass fiber filter. Also contained in the sample box
was a set of four Greenburg-Smith impingers in an ice bath to trap
condensible organic matter and moisture. Only the second impinger
had the original impinger tip; the other three tips had been removed
to decrease the pressure drop. The first impinger was filled with
50 milliliters of distilled water to absorb the organic matter. The
second and third impinger.s were left empty to trap moisture. The
fourth impinger was filled with 175 grams of silica gel to absorb
any remaining moisture. From the last impinger, the sample was
conveyed to the particulate meter box by a flexible umbilical cord.
The meter box contains a dry gas meter to determine volumetric
flow, a calibrated orifice across an inclined/vertical manometer to
determine the instantaneous sampling rate, a vacuum pump, and the
electrical controls for sampling. By using an on-off valve and a
bypass valve, the gas sample velocity in the nozzle was adjusted to
coincide with the stack gas velocity so that sampling could be
conducted isokinetically.
53
-------
12 13
21
1. PROBE TIP
2. COUPLING
3. PROBE
4. CYCLONE
5. FILTER HOLDER
6. HEATER BOX
7. ICE BATH BOX
8. IMPINGER
9. IMPINGER
10. IMPINGER
11. IMPINGER
12. THERMOMETER
13. CHECK VALVE
14. VACUUM TUBING
15. VACUUM GAUGE
16. NEEDLE VALVE
17. VACUUM PUMP
18. BY-PASS VALVE
19. DRY GAS METER
20. CALIBRATED ORIFICE
21. DUAL MANOMETER
22. PITOT TUBE
Figure A-1. Standard PHS participate sampling train.
Total particulate was the sum of the following:
1. The weight of the particulate on the filter
2. The weight of the particulate in the cyclone
3. The weight of the particulate residue from the probe,
cyclone, filter, and impinger acetone washings
4. The weight of the particulate found in an ether-chloroform
extraction of the impinger water and
5. The weight of the particulate residue after the impineer water
is evaporated.
All weights were reported to the nearest 0. 1 milligram..
54
BRASS AND BRONZE INDUSTRY
-------
Gas sampling included tests for concentrations of CO, CO2, SO2,
O2, and hydrocarbons, all of which were conducted simultaneously
from a specially instrumented mobile van. The gas samples were
taken from the effluent by a. probe, through a heated filter to remove
any particulates present, and then through a water knockout. The
samples were then conveyed through an umbilical cord into the van,
where the gases were analyzed. Tests for concentrations of CO,
CO2, and SO2 were carried out by nondispersive infrared analyzers;
O2 concentrations were found with a paramagnetic oxygen and
analyzer; and hydrocarbon concentrations were found with a flame
ionization analyzer. Concentration of each gas, expressed in either
percentages or parts per million, were then recorded automatically
by a12-channelrecorder.
Modifications
Particulate size was not expected to exceed 5 microns down-
stream from the baghouses. Thus, the cyclone collector in the
particulate sample box, which collects particulates larger than 5
microns, was not needed at the sampling points downstream from
the baghouses. The cyclone was removed, and the standard filter
was replaced with a long-neck filter. This modification not only
eliminated unnecessary equipment but also simplified the stream
flow and reduced the amount of glassware that had to be cleaned.
Appendix A 55
-------
APPENDIX B. NAPCA TEST DATA
Valid inferences can best be drawn from test data when the
original data are supplied. The test data summarized in the body
of the report are presented in detail in Tables B-l through B-6
Table B-l. NAPCA TEST DATA: KEY
Test
A
B
C
D
E
F
G
H
I
Process
Rotary
Rotary
Reverberatory
Reverberatory
Cupola
Reverberatory
Rotary
Cupola
Cupola
Location
Inlet
Inlet
Inlet
Outlet
Outlet
Outlet
Outlet
Inlet
Inlet
Inlet
Outlet
Outlet
Outlet
Outlet
Inlet
Outlet
Outlet
Outlet
Inlet
Inlet
Inlet
Outlet
Inlet
Inlet
Inlet
Inlet
- Outlet
Outlet
Sample No.
1
2
3
4
5
6
7
8
10
11
12
13
14
15
16
19
20
21
22
23
24
25
26
27
28
30
29
31
57
-------
Table B-2. PARTICULATE RESULTS
Sample
No.
1
2
3
4
5
6
7
8
10
11
12
14
15
16
19
30
21
22
23
24
25
26
27
28
29
30
31
Probe and
cyclone
gr/scfa
0.003
0.013
0.005
0-0004
0.005
0.004
0.003
0.534
0-634
0.045
0.002
0-012
0.007
0.064
0.010
0.009
0.006
1.2662
_b
0.0196
0.0036
0.1707
0.0119
0.1005
0.2136
0.0199
0.0215
Ib/hr
0.764
3.82'
1.54
0.132
1.33
1.17
0-843
61-22
76-13
6.71
0-563
2.42
1.38
20-17
3.04
2-78
1.80
67.51
0.94
0.56
16.79
1.59
11.4
19.49
4.46
5.55
Probe, cyclone,
and filter
gr/scf
0-104
0-139
0-027
0-0052
0-012
0-007
0-010
1-69
1-33
0.085
0-014
0-025
0-018
0-665
0-012
0-015
0-011
7-0036
0.0729
0.0125
1.0242
0-0440
0-3619
0-3534
0-0235
0-0226
Ib/hr
29-85
41-98
8.48
1-613
3.49
2.04
3-21
193-4
159-2
12-77
3-16
5-15
3-63
211.2
3.84
4.67
3-40
373-42
3.51
1.93
100.72
5.89
41.07
32.24
5.24
5.85
Total (includes
water residue)
gr/scf
0.105
0.141
0.030
0-0057
0.018
0-011
0-021
1.69
1.33
0.085
0.014
0.025
0-031
0-680
0-027
0-030
0.020
9.3799
11-5779
0.1771
0.0140
1-0291
0.0517
0.3729
0-3845
0.0292
0.0359
Ib/hr
30.05
42.75
9.54
1.78
5.18
3.32
6.39
194.2
159-3
12.81
3.32
5.13
6.37
215.9
8.38
9.25
6.38
500.12
681.11
8.54
2-17
101.2
6.93
42.33
35-07
6.52
9-29
aStandard cubic foot, i.e., dry gas at 70 °F and 29.92 in. Hg.
bDashes indicate samples were mixed.
58
BRASS AND BRONZE INDUSTRY
-------
Table B-3. MOISTURE CONTENT AND GAS VOLUME
Sample No.
1
2
3
4
5
6
7
8
10
11
12
14
15
16
19
20
21
22
23
24
25
26
27
28
29
30
31
Percent HgO
2.3
2.3
2.9
2.6
4.5
3.1
3.2
10.9
7.2
3-1
5.0
3.0
5.0
2.0
2.3
1.7
3.7
23.9
16.7
8.5
4.5
1.7
1.8
2.7
1.7
1.1
1.8
scfm
33,510
35,278
36,765
13,999
33,926
33,807
36,121
13,374
14,020
17,559
27,049
24,107
23,882
37,066
36,112
36,556
37,384
6,222
6,864
5,623
18,052
11,475
15,633
13,245
10,644
26,058
30,159
Appendix B
59
-------
Table B-4. LABORATORY DATA"
Sainplu
No.
J
>)
it
'1
5
B
7
8
9
10
11
ia
13
I'l
15
IB
17
18
1(1
ao
ai
aa
a 3
21
ar,
36
27
38
29
30
ii1
SOlVHIll,
axtrtuii oi'
bnplnner
wulor, ing
1.5
2.8
1.8
O.'l
0.2
0.0
1.7
'l.'l
.1)
2-7
1.8
2.8
_c,
0.2
2.8
'1.0
it.l
2.7
1.7
'1.0
-1.0
itC.O
8.0
2.0
0.0
1.0
0.0
1.0
0.0
ImnlnKHi'
wutur
I'HHltJuy,
inn
'1.0
20-8
s.o
0.1
6.6
5.3
17.0
3.8
1.2
3.0
2.7
1.6
0.9
0.5
12.8
-
18,0
21. J
14.0
7.0
1,500.0
11.0
1.2.0
7.0
5.0
3.0
0.0
1.0
2.0
Iinpiii(j;ni'
aootont)
wauli,
mK
3.7
3.6
IB. 9
27. H
6.5
5.3
O.'l
3.0
14.5
1'!.2
13.9
7.0
5.1
4.5
4.5
-
-
3.9
6.3
6.5
12,000.0
__n
540.0
32.0
28.0
8.0
7.0
8.0
14.0
11,. 0
Cyclonu
proba
WHBll,
HIK
41.0
144.1
17.7
14.6
13.7
11.0
0,8
'1,604.2
8,470.4
287.0
95.8
10.1
ai. a
13.1
129.0
-
-
1,7.0
16.5
10.7
0,400.0
33,000.0
11,0.0
120.0
1,300.0
20.0
100.0
28.0
110.0
21.0
Filter
holder
WUHh,
nil-:
23.9
3.0
0.0
17.7
8.8
4.9
5.1
40.7
-
-
21.0
7.0
19.5
11.6
-
3.4
1.5
0.2
Filter
purlloulute,
nig
873.5
1,437.4
83.7
135.8
15.0
2.8
12.7
9,938.9
9,234.0
245.3
426.8
.d
18.9
10.0
1 ,223.2
-
0.7
4.9
3.0
29,000.0
45,000.0
300,0
300.0
0,500.0
54.0
260.0
5.0
72.0
1.0
Total
purHouluto,
mg
947.6
1,013.3
107.7
190.4
51.4
39.3
49.7
14,001.0
-
17,789.4
551. 3
502.7
Void
46.4
56.4,
1,385.0
-
.
40.7
53.0
30.1
47,411,0
79,504.0
996.0
472.0
7,837.0
87.0
371.0
41.0
198.0
3B.O
SIHoii
gel
molntu.ru,
R
00.2
62.9
20,3
126.7
14.8
10.5
11.8
42.0
.
07.8
33.6
,128.1
7,5
8,1
7.5
13.5
.
.
8,4
10.5
19.0
60.0
49.0
137.0
27.0
38.0
5.0
4.0
5.0
1.0
4,0
"All bliuikw liavu Ijtion wibli'tictiHl. SamploB \ through 21; uoutoiie blank, 0.0 nig/200 mil chloroform'
titlinr blank, J.) mg/175 ml; watur blank, ],8 mg/100 nil. Samploi-J gg through 31; uootoiiu bluilk,
1.9 oiK/200 ml; ehJorol'orm-alliHi' bluilk, 0.9 nig/225 ml; walor blank, 1.0 mg/230 ml.
''NO HIUJIplH I'IKill'JVOd.
°Siwiipl(i lotfl. Ill laboratory,
(lPtirl, <>r njU-tr nili-inlng from fluid.
"impliiHHc afiolonu wunli and oyoloua probe wuuli wuru mixyd.
60
BRASS AND BRONZE INDUSTRY
-------
Table B-5. GAS ANALYSES
Sample No.
1
2
3
4
5
6
7
8
10
11
12
13
14
15
16
19
20
21
22
23
24
25
26
27
28
29
30
31
CO, ppm
6.9
10.8
7.5
8.6
49.4
27.1
91.0
42.2
7.7
27.6
23.2
93.5
963
556
1,575
1,575
1.832
3.232
27
9
20
1,100
500
1.100
500
C02. %
1.11
0.28
0.14
0.63
0.65
0.63
1.43
1.39
0.70
0.54
0.89
1.25
1.45
1.76
1-40
1.40
1.41
1.35
0.40
0.34
0-57
0.49
0.21
0-49
0.21
Og, %
18.0
18.2
18.5
18.2
17.0
17.0
17.5
18.1
17.8
17.8
17.9
16.8
16-4
16.1
18.9
18.9
18.9
19.0
19.1
18.9
19.0
19.4
19.4
19.4
19.4
Hydrocarbons, ppm
0.16
0.16
0.37
0.25
0.17
0.17
0.30
0.03
0.02
0.05
0.03
0.14
0.14
0.12
0.49
0.49
0.34
0.36
Appendix B
61
-------
Table B-6. GASEOUS EMISSIONS FROM BRASS- AND BRONZE-SMELTING FURNACES1
Furnace
Rotary
Reberberatory
Blast
Test
A
G
C
F
E
H
I
Og, %
18.2
17.9
19.0
18.9
19.4
19.4
COg, %
0.63
0.89
0.57
1.39
0.49
0.21
CO, ppm
8.6
23.2
20
2,200 (150.2 Ib/T)
1,100 ( 72.5 lb/T)
500 ( 38.2 lb/T)
SOg, ppm
t
10
<1
1
1
NOg, ppm
<0.1
<0-1
0.1
0.1
HgS, ppm
<1
<1
<1
<1
Hydrocarbons
as CH^, ppm
0.25
0.03
0.40
Total
halogens, ppm
<1
<1
<1
<1
CO
a
ca
O
aOg, COg, CO, and CH4, data are integrated samples over one cycle of the furnace; SOg, NOg, HgS and Halogen data are detector tube samples.
''Blanks indicate data not available.
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APPENDIX C. MEMBERS OF BRASS
AND BRONZE INGOT INSTITUTE
300 WEST WASHINGTON STREET, CHICAGO, ILLINOIS
Ajax Metal Division of
H. Kramer and Company
46 Richmond Street
Philadelphia 23, Pennsylvania
The G. A. Avril Company
Este Avenue and B&O R.R.
Cincinnati 32, Ohio
W. J. Bullock, Inc.
P. O. Box 539
Fairfield, Alabama
Benj. Harris and Company
llth and State Streets
Chicago Heights, Illinois
H. Kramer and Company
1347 West 21st Street
Chicago 8, Illinois
R. Lavin and Sons, Inc.
3426 South Kedzie Avenue
Chicago 23, Illinois
Roessing Bronze Company
Mars, Pennsylvania
I. Schumann and Company
4391 Bradley Road P.O. Box 2219
Cleveland 9, Ohio
Sipi Metals Corporation
1720 North Els ton Avenue
Chicago 22, Illinois
S-G Metals Industries, Inc.
Second and Riverview
Kansas City 18, Kansas
United States Metal Products Company
P. O. Box 1067
Erie, Pennsylvania
ftU. S. GOVERNMENT PRINTING OFFICE: 1969—395-978/27
63
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