United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-86/049 Mar. 1987
Project Summary
Nonferrous Industry Particulate
Emissions: Source Category
Report
Mark Burnett and Andrew Minden
The objective of this study was to
develop participate emission factors
based on cutoff size for inhalable par-
ticles for the nonferrous industry. After
a review of available information char-
acterizing participate emissions from
nonferrous plants, the data were sum-
marized and rated in terms of reliability.
Size specific emission factors were
developed from these data for the major
processes used in the manufacture of
nonferrous metals. A detailed process
description was presented with em-
phasis on factors affecting the genera-
tion of emissions. A replacement fcr
Sections 7.1 (Primary Aluminum Pro-
duction), 7.3 (Primary Copper Smelt-
ing), 7.6 (Primary Lead Smelting), 7.7
(Primary Zinc Smelting), and 7.11
(Secondary Lead Smelting) of EPA re-
port AP-42, A Compilation of Air Pol-
lutant Emissions Factors, was prepared,
containing the size specific emission
factors developed during this program.
This Project Summary was developed
by EPA's Air and Energy Engineering Re-
search Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that Is fully docu-
mented In a separate report of the same
title (see Project Report ordering In-
formation at back).
Introduction
The purpose of this program was to
summarize the best available information
on emissions of inhalable particulate
matter in the nonferrous industry. The
main objective of the program was to
develop reliable size-specific emission
factors for the various processes used in
the production of nonferrous metals. Both
uncontrolled and controlled emission fac-
tors are presented in the report. The
uncontrolled factors represent emissions
which would result if the particulate
control device (e.g., baghouse, ESP) were
bypassed, and the controlled factors
represent emissions emanating from a
particular type of control system. The
size-specific emission factors are gen-
erally based on the results of simul-
taneous sampling at the inlet and outlet
of the control device(s), utilizing a variety
of particle sizing techniques. Other ob-
jectives of this program were to present
current information on the nonferrous
industry as well as prepare a replacement
for Sections 7.1,7.3,7.6,7.7, and 7.11 in
EPA report AP-42, "A Compilation of Air
Pollutant Emissions Factors."
The above objectives were met by a
thorough literature search which
included:
• Data from the inhalable particulate
characterization program,
• Fine Particle Emissions Inventory
System (FPEIS),
• AP-42 background file at EPA's
Office of Air Quality Planning and
Standards (OAQPS),
• State and local air pollution control
agencies, and
• Various industry sources
The emission data contained in the
reference documents were reviewed,
analyzed, summarized, and ranked ac-
cording to the criteria established by
OAQPS as published in the EPA report,
"Technical Procedures for Developing
AP-42 Emission Factors and Preparing
AP-42 Sections," April 1980. After rank-
ing the data, emission factors were cal-
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Table 1. Uncontrolled Emission Factors and Particle Size Distribution For Roof Monitor
Fugitive Emissions From Prebake Aluminum Cells
EMISSION FACTOR RATING: C
Particle
size,
nm
IS
10
5
2.5
1.25
0.625
Cumulative
mass%
< stated
size
65
58
43
28
18
13
Cumulative emission factors
kg/MgAI
1.62
1.45
1.08
0.70
0.46
0.33
Ib/tonAI
3.23
2.90
2.15
1.40
0.92
0.67
Total
100
2.5
5.0
Table 2. Uncontrolled Emission Factors and Particle Size Distribution For Roof Monitor
Fugitive Emissions From HSS Aluminum Cells
EMISSION FACTOR RATING: D
Particle
size.
nm
15
10
5
2.5
1.25
0.625
Cumulative
mass%
< stated
size
39
31
23
17
13
8
Cumulative emission factors
kg/MgAI
1.95
1.55
1.15
0.35
0.65
0.40
Ib/ton At
3.9
3.1
2.3
1.7
1.3
0.8
Total
100
5.0
10.0
Table 3. Uncontrolled Emission Factors and Particle Size Distribution For Primary
Emissions From HSS Reduction Cells
EMISSION FA C TOR RA TING: D
Particle
size,
nm
15
10
5
2.5
1.25
0.625
Cumulative
mass%
< stated
size
63
58
50
40
32
26
Cumulative emission factors
kg/MgAI
30.9
28.4
24.5
19.6
15.7
12.7
Ib/ton Al
61.7
56.8
49.0
39.2
31.4
25.5
Total
100
49.0
98.0
culated using the highest quality data
available. The quality of the data used to
develop each emission factor is indicated
by the emission factor rating.
Process control system operating data
as well as general industry information
were also obtained and summarized as
general background information. It was
not part of this program to provide detailed
engineering analyses, product specifica-
tions, or detailed evaluation of trends in
the industry.
Summary of Results
Primary Aluminum
Aluminum metal is manufactured by
the Hall-Heroult process, which involves
the electrolytic reduction of alumina dis-
solved in a molten salt bath of cryolite
(Na3AIF6) and various salt additives. The
electrolytic reduction occurs in shallow
rectangular cells (pots), which are steel
shells lined with carbon. Carbon elec-
trodes extending into the pot serve as the
anodes, and the carbon lining the steel
shell is the cathode. Molten cryolite func-
tions as both the electrolyte and the
solvent for the alumina.
Emissions from aluminum reduction
processes consist primarily of gaseous
hydrogen fluoride and particulate fluo-
rides, alumina, carbon monoxide (CO),
volatile organics, and sulfur dioxide (S02)
from the reduction cells; and fluorides,
vaporized organics, and SO2 from the
anode baking furnaces.
A variety of control devices have been
used to abate emissions from reduction
cells and anode baking furnaces. To
control gaseous and particulate fluorides
and particulate emissions, one or more
types of wet scrubbers (spray tower and
chambers, quench towers, floating beds,
packed beds, Venturis, and self-induced
sprays) have been applied to reduction
cells and to anode backing furnaces. Also,
particulate control methods — e.g., ESPs
(wet and dry), multiple cyclones, and dry
alumina scrubbers (fluid bed, injected,
and coated filter types) — are used with
baking furnaces and reduction cells. Also,
the alumina adsorption systems are being
used to control both gaseous and par-
ticulate fluorides by passing the pot off-
gases through the entering alumina feed,
which adsorbs the fluorides. Baghouses
are then used to collect residual fluorides
entrained in the alumina and recycle
them to the reduction cells.
Uncontrolled emissions from aluminum
reduction cells are given in Tables 1 to 3.
Primary Copper
In the U.S., copper is produced from
sulfide ore concentrates principally by
pyrometallurgical smelting. Because the
ores usually contain less than 1 % copper,
they must be concentrated before trans-
port to smelters. Concentrations of 15-
35% copper are produced at the mine site
by crushing, grinding, and flotation. The
conventional pyrometallurgical copper
smeiiing process includes roasting of ore
concentrates to produce calcine, smelting
of roasted (calcine feed) or unroasted
(green feed) ore concentrates to produce
matte, and converting of the matte to
yield blister copper product (about 99%
pure).
Roasters, smelting furnaces, and con-
verters are sources of both particulate
matter and S02. Copper and iron oxides
are the primary constituents of the par-
ticulate matter, but other oxides (e.g., of
arsenic, antimony, cadmium, lead, mer-
cury, and zinc) may also be present, with
metallic sulfates and sulfuric acid mist.
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Single stage ESPs are widely used in the
primary copper industry to control par-
ticulate emissions from roasters, smelting
furnaces, and converters.
The process sources of particulate
matter are also the potential fugitive
sources of these emissions: roasting,
smelting, converting, fire refining, and
slag cleaning. The actual quantities of
emissions from these sources depend on
the type and condition of the equipment
and on the smelter operating techniques.
Although emissions from many of these
sources are released inside a building,
ultimately they are discharged to the
atmosphere.
Fugitive emissions from primary copper
smelters are captured by applying either
local or general ventilation. Once cap-
tured, emissions may be vented directly
to a collection device or be combined
with process offgases before collection.
Close fitting exhaust hood capture sys-
tems are used for multiple hearth roasters
and hood ventilation systems for smelt
matte tapping and slag skimming. For
converters, secondary hood systems or
building evacuation systems are used.
Size-specific process emission factors
are given in Tables 4 and 5.
Primary Lead Smelting
Lead is usually found naturally as a
sulfide ore containing small amounts of
copper, iron, zinc, and other trace ele-
ments. It is usually concentrated at the
mine from an ore of 3-8% lead to a
concentrate of 55-70% lead, containing
13-19 wt % free and uncombined sulfur.
Processing involves three major steps: (1)
sintering, in which the concentrated lead
and sulfur are oxidized to produce lead
oxide and S02, (2) reducing the lead
oxide contained in the sinter to produce
molten lead bullion, and (3) refining the
lead bullion to eliminate impurities.
Each of the three major lead smelting
process steps generates substantial
quantities of particulates. Particulate
emissions from blast furnaces contain
many different kinds of material, including
a range of lead oxides, quartz, limestone,
iron pyrites, iron-lime-silicate slag, arse-
nic, and other metallic compounds as-
sociated with lead ores. These particles
readily agglomerate and are primarily
submicron in size, difficult to wet, and
cohesive. They will bridge and arch in
hoppers. Minor quantities of particulates
are generated by ore crushing and mate-
rials handling.
The most commonly used high effici-
ency particulate control devices used in
Table 4. Particle Size Distribution and Size Specific Emission Factors For Multiple Hearth
Roaster and Reverberatory Smelter Operations"
EMISSION FACTOR RATING: D
Cumulative mass %
< stated size
Particle
size, urn
15
10
5
2.5
1.25
0.625
Uncontrolled
100
100
100
97
66
25
ESP
controlled
100
99
98
84
76
62
Cumulative emission factors
Uncontrolled
kg/Mg
47
47
47
46
31
12
Ib/ton
95
94
93
80
72
59
ESP controlled
kg/Mg
0.47
0.47
0.46
0.40
0.36
0.29
Ib/ton
0.95
0.94
0.93
0.80
0.72
0.59
Total
100
100
47
95
0.47 0.95
* Expressed as units/unit weight of concentrated ore processed by the smelter.
Table 5. Particle Size Distribution and Size Specific Emission Factors For Copper Converter
Operations8
EMISSION FACTOR RATING: E
Cumulative mass %
< stated size
Particle
size, urn
15
10
5
2.5
1.25
0.625
Uncontrolled
NR
59
32
12
3
1
ESP
controlled
100
99
72
56
42
30
Cumulative emission factors
Uncontrolled
kg/Mg
NR
10.6
5.8
2.2
0.5
0.2
Ib/ton
NR
21.2
11.5
4.3
1.1
0.4
ESP controlled
kg/Mg
0.18
0.17
0.13
0.10
0.08
0.05
Ib/ton
0.36
0.36
0.26
0.20
0.15
0.11
Total
100
too
18
36
0.18 0.36
" Expressed as units/unit weight of concentrated ore processed by the smelter. NR - not reported
because of excessive extrapolation.
lead smelter operations are fabric filters
and ESPs, which often follow centrifugal
collectors and tubular coolers (pseudo-
gravity collectors).
Size-specific emission factors for con-
trolled emissions from a primary lead
blast furnace are given in Tahie 6. Size-
specific emission factors for fugitive
emissions generated at a primary lead
processing plant are given in Tables 7
through 9.
Secondary Lead Processing
The secondary lead industry processes
a variety of lead-bearing scrap and residue
to produce lead and lead alloy ingots,
battery lead oxide, and lead pigments
(Pb304 and PbO). Processing may involve
scrap pretreatment, smelting, and refin-
ing/casting. Scrap pretreatment is the
partial removal of metal and nonmetal
contaminants from lead-bearing scrap
and residue. Processes used for scrap
pretreatment include battery breaking,
crushing, and sweating. Smelting is the
production of purified lead by melting
and separating lead from metal and
nonmetallic contaminants and by reduc-
ing oxides to elemental lead. Refining/
casting is the use of kettle type furnaces
for remelting, alloying, refining, and
oxidizing processes.
Reverberatory smelting furnaces emit
particulates consisting of oxides, sulfides,
and sulfates of lead, antimony, arsenic,
copper, and tin, as well as unagglomer-
ated lead fume. Emissions are generally
controlled with settling and cooling
chambers followed by a baghouse. Wet
scrubbers are sometimes used to reduce
S02 emissions. However, because of the
small particles emitted from reverberatory
furnaces, baghouses are more often used
than scrubbers for particulate control.
Emissions from blast furnaces occur at
charging doors, the slag tap, the lead
well, and the furnace stack. Emissions
from the charging doors and the slag tap
are hooded and routed to the devices
treating the furnace stack emissions.
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Table 6. Lead Emission F
Blast Furnace Fli
Particle
size, Co
15
10
6
2.5
1.25
1.00
0.625
Total
Table 7. Uncontrolled Le
Sinter Machine
Particle
size, Ct
15
10
6
2.5
1.25
1.00
0.625
Total
:actors and Particle Size Distribution For Baghouse Controlled
ue Gases
EMISSION FACTOR RATING: C
Cumulative emission factors
imulative mass %
< stated size
98
86.3
71.8
56.7
54.1
53.6
52.9
100.0
kg/Mg
1.17
1.03
0.86
0.68
0.65
0.64
0.63
1.20
Ib/ton
2.34
2.06
1.72
1.36
1.29
1.28
1.27
2.39
iad Fugitive Emission Factors and Particle Size Distribution For
EMISSION FACTOR RATING: D
Cumulative emission factors
jmu/ative mass %
< stated size
99
98
94.1
87.3
81.1
78.4
73.2
100.0
kg/Mg
0.10
O.JO
0.09
0.08
0.07
0.07
0.07
0.10
Ib/ton
0.19
0.19
0.17
0.16
0.15
0.15
0.14
0.19
Blast furnace particulates are smaller
than those emitted from reverberatory
furnaces and are suitable for control by
scrubbers or fabric filters downstream of
coolers.
Emissions from oxidizing furnaces are
economically recovered with baghouses.
The particulates are mostly lead oxide,
but they also contain lead and other
metals.
Size-specific emission factors for con-
trolled blast furnace flue gases are given
in Table 10.
Primary Zinc Smelting
Zinc is found primarily as the sulfide
ore sphalerite (ZnS). Zinc ores typically
contain 3-11% zinc. Zinc ores are pro-
cessed into metallic slab zinc by the
electrolyte process or the pyrometal-
lurgical smelting process.
Electrolytic processing involves four
major steps: roasting, leaching, purifica-
tion, and electrolysis. Pyrometallurgical
processing involves three major steps:
roasting, sintering, and retorting.
Each of the two zinc smelting processes
generates emissions along the various
process steps. Most of the particulate
emissions in the primary zinc smelting
industry are generated in the ore con-
centrate roasters. Particulate emission
controls are generally required for the
economical operation of a roaster: cy-
clones and ESPs are the primary controls
used
Table 8. Uncontrolled Lead Fugitive Emission Factors and Particle Size Distribution For
Blast Furnace
Total mass emission factors for con-
trolled and uncontrolled emission factors
for point sources in a zinc smelting plant
are given in Table 11.
EMISSION FACTOR RATING: D
Particle
size.
Cumulative emission factors
Cumulative mass %
< stated size
kg/Mg
Ib/ton
15
10
6
2.5
1.25
1.00
0.625
94
89
83.5
73.8
65.0
61.8
54.4
0.11
0.11
0.10
0.09
0.08
0.07
0.06
0.23
0.21
0.20
0.17
0.15
0.15
0.13
Total
100.0
0.12
0.24
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Table 9. Uncontrolled Lead Fugitive Emission Factors and Particle Size Distribution For
Reverberating Furnace
EMISSION FACTOR RATING: D
Panicle Cumulative emission factors
size. Cumulative mass %
urn < stated size kg/Mg Ib/ton
15 99 0.24 0.49
10 98 0.24 0.48
6 92.3 0.22 0.45
2.5 80.8 0.20 0.39
1.25 67.5 0.16 0.33
1.00 61.8 0.15 0.30
0.625 49.3 0.12 0.24
Total 100.0 0.24 049
Table 10. Emission Factors and Particle Size Distribution For Baghouse Controlled Blast
Furnace Flue Gases3
EMISSION FACTOR RATING: D
Particle
size,
fim
15
10
6
25
1.25
1.00
0.625
< stated size
93.0
89.0
83.5
71.0
44.5
33.0
14.5
Cumulative emission factors
kg/Mg
0.22
0.21
0.20
0.17
0.11
0.08
0.03
Ib/ton
0.45
0.43
0.40
0.34
0.21
0.16
0.07
Total 700.0 0.24 0.48
a Units are for lead, as produced.
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Table 11. Paniculate Emission Factors For Primary Slab Zinc Processing3
Process
Roasting
Multiple hearthb
Suspension0
F/uidized beer
Sinter plant
Uncontrolled
With cyclone'
With cyclone
and ESP1
Vertical retort
Electric retort
Electrolytic process
Emission
Uncontrolled Factor Controlled
kg/Mg
113
1000
1083
62.5
NA
NA
7.15
100
3.3
nanny
Ib/ton kg/Mg Ib/ton
227 E — —
2000 E 48
2167 E — —
125 E - -
NA 24. 1 48.2
NA 8.25 16.5
14.3 D — —
200 E — —
6.6 E — —
Emission
Factor
Rating
E
D
D
3 Based on quantity of slab zinc produced. NA = not applicable Dash = no data.
b Averaged from an estimated 10% offeed released as paniculate emissions, zinc production rate
at 60% of roaster feed rate, and other estimates.
c Based on an average 60% of feed released as paniculate emission and a zinc production rate of
60% of roaster feed rate Controlled emissions based on 20% dropout in waste heat boiler and
99 5% dropout in cyclone and ESP.
"Based on an average 65% of feed re/eased as paniculate emissions and a zinc production rate of
60% of roaster feed rate
e Based on unspecified industrial source data.
'Data not necessarily compatible with uncontrolled emissions.
M. Burnett and A. Minden are with A cur ex Corporation, Mountain View, CA
94O39.
Dale L. Harmon is the EPA Project Officer (see below).
The complete report, entitled "Nonferrous Industry Paniculate Emissions:
Source Category Report, "(Order No. PB 87-140 935/A S; Cost: $24.95, subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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EPA/600/S7-86/049
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