SEPA
United States
Environmental Protection
Agency
Industrial Environmental Research EPA-600/2-80-079
Laboratory May 198O
Cincinnati OH 45288
Research and Development
Control of Copper
Smelter Fugitive
Emissions
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/2-80-079
May 1980
CONTROL OF COPPER SMELTER
FUGITIVE EMISSIONS
by
Timothy W. Devitt
PEDCo Environmental, Inc.
11499 Chester Road
Cincinnati, Ohio 45246
Contract No. 68-02-2535
Project Officer
A. B. Craig, Jr.
Metals and Inorganic Chemicals Branch
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
-------
DISCLAMIER
This report has been reviewed by the Industrial Environmental
Research Laboratory-Cincinnati, U.S. Environmental Protection
Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or
recommendation for use.
11
-------
FOREWORD
When energy and material resources are extracted, processed,
converted, and used, the related pollutional impacts on our
environment and even on our health often require that new and
increasingly more efficient pollution control methods be used.
The Industrial Environmental Research Laboratory - Cincinnati
(lERL-Ci) assists in developing and demonstrating new and
improved methodologies that will meet these needs both efficiently
and economically.
This report evaluates potential solutions for the collection of
fugitive emissions from copper smelters. A brief estimate of
emission rates has been provided based on available sampling
reports. The results of this investigation will enable EPA to
identify potential control technology applications not currently
used by the domestic industry and to conduct engineering testing
and evaluation on these technologies. Questions or comments
regarding this report should be addressed to the Metals and
Inorganic Chemicals Branch of the Industrial Environmental
Research Laboratory in Cincinnati.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
iii
-------
ABSTRACT
This report presents the results of a study of fugitive emission con-
trols for the copper industry. The study was conducted by PEDCo Environ-
mental, Cincinnati, Ohio, under contract to the United States Environmental
Protection Agency.
During the study period, many of the domestic primary copper smelters
were visited to investigate current controls being used and potential appli-
cations which might be proposed. The purpose of the study was to document
improved controls as well as identify avenues for new research where controls
are currently unavailable.
The report presents existing and proposed emission control devices for
many of the furnaces commonly used in the primary copper industry, as well
as for hot metal transfer devices such as launders and ladles or other
transport devices. Several of the devices that are reported are currently
under study by the Nonferrous Metals and Minerals Branch to determine their
control effectiveness on both the pilot and full-scale application.
iv
-------
CONTENTS
Page
Figures VI
Tables IX
Acknowledgment x
1. Introduction 1
2. Overview of Copper Smelting Processes 2
3. Basic Copper Smelting Processes and Related
Emissions 6
Dryers and Roasters 6
Reyerberatory Furnace 9
Peirce-Smith Converter 12
Anode Furnace 19
4. Alternative Copper Smelting Processes and
Related Emissions 20
Noranda Furnace 20
Electric Furnace 22
Flash Smelting Systems 24
Hoboken Converter 28
5. Summary of Fugitive Emissions from Copper
Smelters 33
6. Current Controls and Proposed Modifications 47
Hooding Systems 49
Roof Monitors 63
Building Enclosure 63
Air Curtains 64
7. Proposed Alternative Controls and Process
Changes 67
Cascading System, Staggered System, and
Induction Pumping 67
Oxygen Enrichment 69
Q-BOP Furnace 72
Crane Evacuation of Ladle Emissions 74
v
-------
CONTENTS (continued)
Floor-Operated Charging 74
Top-Covered Bottom-Pour Ladles 74
Individual Furnace Enclosures 77
8. References 80
Appendix A Cost Analysis 81
Appendix B Trip Report: Mitsubishi Metal Corp.,
Onahama, Japan 94
VI
-------
FIGURES
Number Page
1 Locations of Primary Copper Smelters in the
United States 3
2 General Flowsheet of the Copper Industry in
the United States 5
3 Countercurrent Direct-Heat Rotary Dryer 7
4 Multiple-Hearth Roasting Furnace 8
5 Fluid-Bed Roaster 10
6 Reverberatory Smelting Furnace 11
7 Peirce-Smith Converter 13
8 Matte Charging Operation 15
9 Position of the Converter During Slagging or
Blister Copper Pouring 16
10 Noranda Continuous Smelter 21
11 Electric Smelting Furnace 23
12 Outokumpu Flash Smelting Furnace 26
13 INCO Flash Smelting Furnace 27
14 Hoboken Converter 29
15 Hoboken Converter with Swingaway Hood 32
16 Material Balance: Multihearth Roasting Furnace 35
17 Material Balance: Reverberatory Furnace After
Multihearth Roaster 36
18 Material Balance: Peirce-Smith Converter After
Reverb and Multihearth 37
-------
FIGURES (continued)
Number
19 Material Balance: Fluid-bed Roaster 38
20 Material Balance: Reverberatory Furnace After
Fluid-bed Roaster 39
21 Material Balance: Peirce-Smith Converter After
Fluid-bed and Reverberatory Furnace 40
22 Material Balance: Noranda Continuous Smelter 41
23 Material Balance: Peirce-Smith Converter After
Noranda Furnace 42
24 Material Balance: Outokumpu Flash Smelting
Furnace 43
25 Material Balance: Peirce-Smith Converter After
Outokumpu Furnace 44
26 f Material Balance: Electric Smelting Furnace 45
27 Material Balance: Peirce-Smith Converter After
Electric Furnace 46
28 Secondary Converter Hood Configuration 50
29 Ajo Smelter, Secondary Emission Collection
System (Sheet 1 of 2) 52
30 Ajo Smelter, Secondary Emission Collection
System (Sheet 2 of 2) 53
31 Side View of Peirce-Smith Converter with
Hooding in Position 54
32 Front View of Fixed, Movable, and Gate Hoods 55
33 Peirce-Smith Converter with Hooding Extended 56
34 Side View of Peirce-Smith Converter During Collar
Pulling or Blister Copper Ladle Removal, with
Hooding Retracted 57
35 Enclosed Swingaway Converter Hood of Nippon
Mineral Company 58
van
-------
FIGURES (continued)
Number Page
36 Air curtain Fugitive Control System 66
37 Cascading Gravity Flow 68
38 Fugitive Emission Collection System for
Cascading Gravity Flow 70
39 Fugitive Emission Collection System for
Cascading/induction/gravity Flow 71
40 Q-BOP Furnace Enclosed in a "Doghouse" to
Prevent Fugitive Emissions 73
41 EOT Crane with Telescopic Stiff Leg 75
42 Modified Charging Machine 76
43 Hydraulic Cylinder Mounted on Barrel of Ladle
Rigging Raises and Lowers Stopper Rod to
Control Flow of Molten Steel from Ladle to
Ingot Mold 78
44 Individual Furnace Enclosure 79
B-l Schematic of the Onahama Converter Emission
Control System 97
B-2 Converter Hooding Arrangement 98
IX
-------
TABLES
Number Page
1 Estmated Fugitive Emissions from Copper
Smelting in Various Process Arrangements 34
2 Summary of Current Fugitive Emission Control
Systems 48
3 Positions of Movable Hoods 61
4 Estimated Retrofitted Hooding
Efficiencies 62
A-l Estimated Capital Costs of Secondary Hooding
at Multiconverter Plant without Baghouse 85
A-2 Estimated Capital Costs of Secondary Hooding
at Multiconverter Plant with Baghouse 86
A-3 Estimated Annual Operating Costs of Secondary
Hooding at a Multiconverter Plant without
Baghouse 87
A-4 Estimated Annual Operating Costs of Secondary
Hooding at a Multiconverter Plant with
Baghouse 88
A-5 Estimated Capital Installed Costs of Air Curtain
Type Hooding with Baghouses at Multiconverter
Plant 90
A-6 Estimated Annual Operating Costs of Air Curtain
Type Hooding with Baghouses at Multiconverter
Plant 91
A-7 Relative Cost Evaluation of Alternative and
Existing Systems 92
A-8 Estimated Energy Requirements for Control of
Fugitive (Gaseous and Particulate) Emissions
at Intakes and Discharge Points 93
-------
ACKNOWLEDGMENT
This report was prepared under the direction of Mr. Timothy
W. Devitt. Mr. L. Yerino was the Project Manager. Project
Officer for the U.S. Environmental Protection Agency was Mr.
A.B. Craig, Jr., of the Industrial Environmental Research
Laboratory, Cincinnati.
The helpful suggestions from plant officials of the copper
smelting facilities and Mr. Henry Dolezal of the U.S. Bureau of
Mines are appreciated.
The report was written -by Mr. L. Yerino,. Mr. T.K. Corwin,
and Mr. R. Price. The cost and energy calculations were com-
puted by Mr. L. Yerino and Mr. M. Giordano.
XI
-------
SECTION 1
INTRODUCTION
This report deals with fugitive emissions from copper
smelting and with emission control measures. The PEDCo study
involved evaluation of the controls now used in the copper
smelting industry and development of suggestions for alternative
control devices and practices.
A brief overview of copper smelting processes (Section 2)
is followed by a more detailed analysis of the conventional
processes, identifying the portions of the operating cycle that
produce fugitive emissions (Section 3). Emphasis is placed on
the Peirce-Smith converter, which is one of the major emission
sources in copper smelting.
Section 4 describes some of the alternative process systems
now in limited use in the United States and in other countries.
These newer types of furnaces and converters, although usually
designed primarily to facilitate production, also reduce the
generation of fugitive emissions and therefore may be regarded
as possible means of emission control. Section 5 summarizes the
fugitive emissions from both conventional and alternative copper
smelting processes; the values are based the small amount of
usable published data.
The balance of the report concerns emission control mea-
sures. The devices and practices in current use are considered,
along with proposed modifications that might enhance control
efficiency (Section 6). Finally, some alternative control sys-
tems are presented (Section 7); these include potential adapta-
tions of equipment now used in other industries and also changes
in the smelting process, ranging from introduction of relatively
simple process devices to major process changes. Potential
problems associated with operation of new equipment, especially
in retrofit installations, are considered, along with the po-
tential benefits in reduction of fugitive emissions. Tables
indicating order-of-magnitude costs of current and alternative
control measures are given in Appendix A.
-------
SECTION 2
OVERVIEW OF COPPER SMELTING PROCESSES
The copper produced by the domestic primary copper industry
is recovered mainly from sulfide ores containing a variety of
minerals. Small amounts of copper are also recovered from oxide
ores, low-grade waste, and imported ores. Because most of the
domestic ore is mined in the southwestern states, most of the
plants are located in that area. Figure 1 shows the locations
of the 16 primary copper smelters in the United States. The
smelting processes recover copper while removing most of the
impurities from the copper ore. Refining removes the remaining
impurities.
Copper is recovered from copper ores primarily by pyro-
metallurgical processing; some hydrometallurgical processing is
done also. Pyrometallurgical processes convert ore concentrate
into an impure copper called blister copper. The process steps
may consist of roasting or drying, smelting, converting, and
fire refining. The anode copper product, which may contain as
much as 99.8 percent copper, is sent to an electrolytic refinery
for final purification.
The ore concentrate, containing about 25 percent copper, is
generally conveyed to the smelter by rail or truck and stored.
From that point, different process steps in various combinations
are used at different smelters. The following brief process
description deals with smelting in a reverberatory furnace, and
the Peirce-Smith converter, the most common process in domestic
use today.
From storage the ore concentrate is conveyed to a dryer or
roaster. After processing, the dried or partially roasted (cal-
cined) ore concentrate is usually transferred in a larry car to
a reverberatory furnace, into which it is charged through pipes
and/or hoppers located at the top or along the side walls. The
concentrate is melted by reverberatory heating. With the addi-
tion of a silica fluxing agent, the melt forms a copper-bearing
matte layer and a waste slag layer. The matte is tapped near
the bottom of the furnace, and the lighter slag is tapped at a
higher elevation. The slag is collected in a slag pot or ladle,
carted to a disposal area, and dumped.
-------
ASARCO (TACOMA)-
ANACONOA (ANACONDA)-
KENNECOTT (GARFIELD)-
KENNECOTT (McGILL>
KENNECOTT (HAYDEN)
INSPIRATION (MIAMI)
ASARCO (HAYDEN)
PHELPS-DODGE (AJO)
MAGMA (SAN MANUEL)
PHELPS-DODGE (DOUGLAS)
PHELPS-DODGE (HIDALGO)
KENNECOTT (HURLEY)
ASARCO (EL PASO)
COPPER RANGE (WHITE PINE)
—i-,_ _
I ' I
•*/ * ~~T'-*s >L-t
•^ 1
>\ /
r ^— — i
\ t
)
\
\
A •
-. T '
• ' , . .'
"T
)
-
\
r~
i
i
/
i
i
/
PHFI P5-nnDRF
\
CITIES SERVICE
(COPPERHILL)
(MORENCI)
Figure 1. Locations of primary copper smelters in the United States.
-------
The matte is collected in a ladle and is transferred by
crane to a Peirce-Smith converter, which is a horizontal cylin-
drical furnace. This furnace converts the matte into blister
copper and slag by reaction with air blown in from below the top
of the bath line. The reaction is exothermic. The slag, which
contains recoverable copper, is poured from the mouth of the
converter into a ladle, then returned to the reverberatory fur-
nace. After the final blowing, the blister copper contains
about 98 to 99 percent copper. It is poured into a ladle, then
transferred to an anode furnace, usually gas-fired, which com-
pletes the smelter refinement of copper. The anode copper,
containing over 99.5 percent copper, is poured from the furnace
into molds or a continuous casting wheel.
The anode copper molds range in weight from 209 to 454 kg.
They are cooled by quenching, then stored or loaded onto rail
cars for delivery to a refinery. Figure 2 is a general flow-
sheet representing the copper industry in the United States.
The figure shows the traditional pyrometallurgical steps just
described, as well as alternative processes currently in limited
use.
-------
SLAG TO DUMP
Figure 2. General flow sheet of the copper industry in the United States.
-------
SECTION 3
BASIC COPPER SMELTING PROCESSES AND RELATED EMISSIONS
DRYERS AND ROASTERS
Some smelters use rotary dryers or roasters to precondition
the concentrate before smelting. At least seven smelters either
dry their concentrates onsite or process feed that has been
dried at a concentrator plant. The main functions of dryers and
roasters are to remove moisture and some impurities from the
concentrate and to preheat the feed to the smelting furnace(s).
Figure 3 shows a countercurrent, direct-heat rotary dryer.1
"Green" concentrate is charged to the dryer through the feed
chute. By means of lifting flights, rotation of the dryer, and
declination of the unit from the feed end to the discharge end,
the concentrate is dried and moved to the point of discharge.
The degree of drying achieved depends on the residence time of
the concentrate in the dryer and the temperature throughout the
dryer. Fugitive emissions occur at the discharge and charging
ends during upsets or when concentrate is charged improperly.
Roasters used at domestic smelters are of two varieties:
multiple-hearth and fluid-bed. Among the domestic smelters,
four plants have multiple-hearth and four have fluid-bed units.
In addition to removing moisture from charged concentrates and
preheating them for charging to a smelting furnace, a roaster
also serves the important function of partially removing some
sulfur from the concentrate to give a working balance of copper,
sulfur, and iron in the calcine product. Basically, sulfur is
removed by converting it to S02 gas. This is done by maintain-
ing control of temperature and air in the roaster so that the
sulfur will ignite and burn (oxidize). The roasting process
also oxidizes iron in the concentrate to ferric oxide, which can
react with silica and be removed as slag in the smelting
furnace. Roasting also helps to volatilize impurities such as
arsenic and antimony, and thus facilitates their removal down-
stream.
The conventional multiple-hearth roaster, illustrated in
Figure 4, is cylindrical and vertical and has from seven to
twelve hearths. The casing is steel, lined with refractory
brick. Concentrate is charged onto the top hearth, on which
rabble arms, driven by a central shaft, move the feed. The
rabble blades or "plows" push the concentrate toward the center
6
-------
FRICTION SEAL
FEED CHUTE
INLET HEAD
(COUNTER FLOW ONLY)
SPIRAL FLIGHTS
NO. 1 RIDING RING
TRUNNION AND
TRUST ROLL
ASSEMBLY
GIRT
GEAR
KNOCKER
BREECHING
SEAL
NO. 2
RIDING
RING
DRIVE
ASSEMBLY
LIFTING
FLIGHTS
BREECHING
TRUNNION ROLL
ASSEMBLY
DISCHARGE
Figure 3. Countercurrent direct-heat rotary dryer
(combustion chamber not shown). (Adopted from Ref. 1.)
-------
RABBLE
ARM
RABBLE
BLADE
CALCINE
HOT AIR
TO EXHAUST
AIR
NATURAL
GAS
COOLING
AIR
Figure 4. Multiple-hearth roasting furnace.
-------
of the hearth, from which it cascades through an opening to the
hearth below. Plows on the next hearth push the concentrate to
the periphery, from which it falls to the hearth below, and so
on. This gradual movement of concentrate back and forth and
down through the hearths exposes the surfaces of the concentrate
and permits the partial roasting of calcine to take place.
Off-gases from a multiple-hearth roaster are approximately
150° to 200°C. Particulates in the gas stream are usually col-
lected by an electrostatic precipitator; the outlet gas contain-
ing some S02 and volatilized compounds is ducted to a stack.
The fluid-bed roaster, illustrated in Figure 5, is cylin-
drical and performs the same function as the multiple-hearth
unit, but works on an entirely different principle. Rather than
being roasted on hearths, the concentrate particles are sus-
pended by an air stream moving upward. Each particle of the
suspended "bed" is in constant agitated motion and is in inti-
mate contact with the air stream. Because this fluidization
roasting exposes much more of the overall surface area of the
concentrate, the reactions are almost instantaneous. Also,
oxygen in the air within the roaster completely reacts with
sulfur and iron; thus the outlet gas contains a higher concen-
tration of S02 than that generated by the multiple-hearth
roaster. This concentrated S02 stream is sent to an acid plant
for SC>2 removal.
Fugitive emissions from the roaster occur by leakage
through the shell or open ports and during the filling of the
transfer car.
REVERBERATORY FURNACE
The workhorse of the U.S. copper industry is the reverbera-
tory furnace (reverb), which was first introduced in 1879 and is
still used in a modified form at 11 of the 16 domestic smelters
(Figure 6). The reverb is an arch-roofed or suspended-roof
horizontal chamber, approximately 35 m long and 10 m wide. Heat
is supplied by fossil-fuel-fired burners located at one end of
the furnace. The reverb receives the charge from the roaster or
dryer and, with heat supplied from the burners, reduces the
charge to matte and slag. The reverb is extremely flexible with
respect to concentrate composition and is capable of accepting
as much as 1800 Mg of material per day.
Operation
Although methods vary considerably, reverbs are generally
charged either through the furnace top or along the top portion
of the side walls. Belt slingers (high speed conveyors), hop-
pers, and Wagstaff guns (inclined chutes) are used to distribute
-------
TUYERE
HEADS
FUGITIVE
EMISSIONS;
NO VALUES
AVAILABLE
OFF-GAS
I
Figure 5. Fluid-bed roaster.
10
-------
CALCINE
FUEL
CONVERTER
SLAG
AIR AND
OXYGEN
BURNERS
OFF-GAS
MATTE
SLAG CHARGING PIPES
Figure 6. Reverberatory smelting furnace.
11
-------
the charge over the molten bath. Drag chains and screw con-
veyors have also been used for charging. One plant processes
"wet, unroasted" concentrate charged to the furnace by means of
charge cans.
In operations at this plant, the concentrate is conveyed
from a filter plant, and lime rock is added. An electric over-
head travelling (EOT) crane places the charge can above one of
the slingers (high-speed belt conveyors), which are adjustable
in height and angle. One of the retractable charging port doors
on the side of the furnace is raised, and feed from the can is
discharged onto the furnace bath area. Slag is drained period-
ically from one end of the furnace and conveyed by launders to
slag pots. The slag can be cooled, solidified, granulated, or
dumped molten. Matte is withdrawn periodically through tap
holes in the lower furnace wall. The matte flows down launders
and into ladles, which are conveyed by overhead cranes to the
converter. Outlet gases from the reverb are generally passed
through waste heat boilers to recover as much of the heat of the
combustion gas as possible.. Usually, the gases are cleaned of
most of the particulates by means of electrostatic precipitators
and vented to the atmosphere.
Emissions
The fugitive emissions from or in the vicinity of a reverb-
eratory furnace occur at openings in the furnace brickwork
(caused by inadequate repair and maintenance or length of time
in service); during charging of calcine or green concentrate;
during addition of converter slag to the furnace; at the slag
and matte launders during tapping operations; and by leakage at
the uptake and the waste heat boiler.
PEIRCE-SMITH CONVERTER
The Peirce-Smith converter is a horizontal, refractory-
lined, cylindrical furnace, generally about 4 m in diameter and
9 m long. An opening in the horizontal side serves as a mouth
for charging feed materials, discharging the products of combus-
tion, and pouring slag and blister copper (see Figure 7). The
converter can rotate through an arc of about 150 degrees from
the vertical for operational purposes. First developed in 1909,
the Peirce-Smith converter is now used at 15 of the 16 domestic
copper smelters, with as many as 9 units installed at one plant.
Two or three converters are generally associated with each
smelting furnace. The Peirce-Smith converter is a relatively
efficient furnace, whose high rates of air flow permit both the
charging of bulky materials and large copper throughputs, typi-
cally about 9 Mg of blister copper per blowing hour.
12
-------
TUYERE
PIPES
OFF-GAS
« . •-•*•
SILICEOUS
FLUX
PNEUMATIC
PUNCHERS
Figure 7. Peirce-Smith converter.
13
-------
Operation: General
In the smelting process, the converter receives molten
matte consisting of copper, iron, sulfur, and small amounts of
other elements. The matte contains 40 to 45 percent copper from
the reverberatory furnace; flux is added from bins or hoppers
located adjacent to the converter. Air for combustion is forced
through the tuyeres, a series of holes in the side of the con-
verter 6 to 8 inches below the normal bath surface. Oxygen in
the air reacts with the iron sulfides to form an iron silicate
slag; this is removed, and the remaining copper sulfide is
oxidized to blister copper. The reaction is exothermic. The
blowing operations remove iron, as a slag iron silicate, and
sulfur, as sulfur dioxide. The resultant product is blister
copper, which is poured into ladles and transported to the anode
furnace.
Operating Phases of a Peirce-Smith Converter
A Peirce-Smith converter ready to come on line is first
preheated, usually by gas or oil-fired burners, until the con-
verter can accept a hot charge. For charging, the converter is
in a "rolled out" position ready to accept matte. A ladle of
matte is transferred by the EOT crane from a smelting furnace to
the converter. The hot metal is poured from a ladle into the
converter (Figure 8). Three to four ladles of matte are charged
to the converter in this manner and blowing begins. A total of
10 to 12 ladles of copper matte may be charged during the slag
blows. A ladle of cold dope (cold material such as copper,
scrap, or high-copper slag) also may be charged during one more
of the slag blows. A fluxing agent, generally silica, usually
is added. Before the converter is tilted back to its upright
position, an air blow is initiated; as the converter is tilted,
this air stream prevents the hot metal from clogging the tuyeres
(typically 40 to 50). Blowing rates range from 42,500 to 68,000
m3air/h.
As the operation proceeds, the lower-density slag floats on
top of the molten layer. As the slag builds up, the converter
is rolled out and slag is removed into a ladle (Figure 9). The
slag, containing 6 to 8 percent copper, can be returned by over-
head crane to the smelting furnace. Additional matte and/or
cold dope are charged to the converter as required, and blowing
begins again. Slag is again removed, and the operations are
repeated until enough copper sulfide has accumulated in the
converter. The slag blows are then complete, and the finish or
copper blow begins.
During the slag and copper blowing periods, sulfur in the
copper/sulfur/iron matte reacts with oxygen in the blowing air
to form sulfur dioxide (S02), most of which is discharged into a
primary hooding system. The concentration of the S02 gas during
14
-------
,
•ass.-*
Figure 8. Matte charging operation,
15
-------
SLAG LADLE OR
BLISTER COPPER
LADU
Figure 9.
Position of the converter during slagging or
blister copper pouring.
16
-------
the slag and copper blows, even with the infiltration of dilu-
tion air, is usually great enough that the gas is sent to an
acid plant for production of sulfuric acid. With the elimina-
tion of impurities, mainly the sulfur as S02 and iron in the
slag, the matte is converted to the blister copper product that
consists of about 98 to 99 percent copper.
Pouring of the blister copper, like the slag, is done
through the mouth of the converter (Figure 9). The filled
ladles of blister copper are transferred by the overhead crane
and dumped into the anode furnaces or refining furnaces. Occa-
sionally some slag may be formed in an anode furnace; this slag
is poured off into a ladle, and then recharged into a converter.
Emissions
All of the Peirce-Smith converters at primary copper smelt-
ers in this country are equipped with primary hoods to direct
the gas flow from the converter when it is in the upright, i.e.,
blowing or "in-stack" position. This gas stream, containing
particulates and S02, is passed through particulate control
equipment and at most smelters is routed to an acid plant for
S02 removal.
Fugitive emissions from a Peirce-Smith converter consist of
those that escape the primary hooding system and those that are
emitted directly from the mouth of the converter when it is
positioned in the "out-of-stack" mode, i.e., when it is receiv-
ing a cold or hot charge, or when slag or blister copper is
poured from the mouth of the converter.
The primary hooding system (Figure 9) at most smelters
consists of a fixed hood with a sliding gate located above and
slightly away from the converter. The primary hooding system is
connected by ducting usually to an ESP. The sliding gate is
lowered close to the converter mouth to help guide the emissions
into the fixed hood and reduce the intake of dilution air during
the blowing period. Minimizing the dilution air serves to
maximize the S02 concentration in the gas stream to an acid
plant.
Regardless of the merits of any primary hooding system,
some of which have been modified to increase collection effi-
ciency, none are 100 percent efficient. The hooding system with
the sliding gate does not form a perfectly tight seal with the
converter body (even with the closest fits, since there must be
some clearance between the two to allow the converter to
rotate). At some plants, because the gates were retrofitted
rather than designed and installed as part of the original
smelter, the gates may not completely cover the converter mouth
nor seal tightly to the primary hood. Emissions therefore
17
-------
escape through the open areas between the gate, the primary
hood, and the converter mouth. The emission rate is dependent
on the size of the openings and the discharge gas flow rate
through the mouth of the converter to the hooding system. Leaks
can also occur between the edges of the gate and the converter
primary hood. Additionally, emissions from even a well designed
and installed hood system will increase in time unless pre-
ventive maintenance is practiced to forestall the effects of
normal wear and tear.
During the frequent transport and charging of materials,
bumping of a gate and guide may cause them to become misaligned
or damaged, thus allowing additional fugitive emissions. Emis-
sions vary among smelters because of restrictions on overhead
space for installation of the primary hood. At smelters that
were originally designed with low crane rail runways, the clear-
ance is limited. In these plants the optimal slope and con-
figuration of the primary hoods have been compromised by lack of
space, and flow of the gases from the mouth of the converter is
impeded. Although the installed system may be the best pos-
sible, it does permit fugitive emissions.
The second category of fugitive emissions from a Peirce-
Smith converter consists of those emitted directly from the
mouth of the converter in the rolled-out position. As the
converter is rolled-out, the gate is usually moved up and away
from the converter mouth for clearance. The blast air is left
on until the bath is below the tuyere level. Even if the blast
air flow is reduced to some minimum rate, fugitive emissions are
still rather heavy. Also, fugitive emissions are heavy when
matte is charged to the converter. Unless a converter is
equipped with a secondary hooding system, emissions that occur
during charging, pouring of slag, or pouring of blister copper
are uncontrolled. When the blast air is turned off, the hot
bath still generates some fugitive emissions, which continue to
leave the converter at a lower rate. Fugitive emissions usually
become heavy also when cold material such as copper scrap is
charged to the converter. Before a Peirce-Smith converter is
rolled back, the blast air is turned on again. Emissions from
within the converter are blown out of the mouth and are not
reasonably controlled until the gate is down and the converter
is in the in-stack position.
Characterization of Emissions
To date, the fugitive emissions from Peirce-Smith conver-
ters have not been collected for the purpose of chemical charac-
terization. Since data are lacking, the following is an esti-
mate of the composition by weight of the constituents: S02 -
90%, Cu - 4%, Fe - 4%, and S - 2%. The fugitive emissions also
contain some trace metals such as arsenic and lead.
18
-------
ANODE FURNACE
The final process at a copper smelter is purification of
the blister copper in an anode furnace. The anode furnace is
usually cylindrical, very similar in shape and size to a
Peirce-Smith converter, and generally lined with magnesite
refractory. Like the Peirce-Smith converter, the anode furnace
is tilted or rolled out to receive its charge, which is poured
from a blister ladle carried from the converter by an EOT crane.
In the upright position, the furnace is blown with a gas high in
hydrogen content. The reaction that takes place removes oxygen
from the bath. This deoxidation of the cuprous oxide (Cu20)
reduces it to nearly pure copper. Most, but not all, of the
oxygen is removed from the molten bath. A small oxygen residue
in the bath is necessary to cast a shape free of blisters or
shrinkage holes.
The anode furnace also serves as a holding furnace, from
which the anode copper product is poured, usually into molds on
a continuous casting wheel. The formed anodes are shipped to an
electrolytic refinery.
Any fugitive emissions from an anode furnace come directly
from its mouth when not hooded. These emissions are minimal.
Most or all of the sulfur, iron, and other impurities have been
removed in preceding operations. The characteristic "greenish
flame" shooting a few feet from the anode mouth during deoxida-
tion probably indicates the presence of some copper in the
off-gas stream.
19
-------
SECTION 4
ALTERNATIVE COPPER SMELTING PROCESSES
AND RELATED EMISSIONS
Several alternatives to the reverberatory furnace and the
Peirce-Smith converter are in use in this country and abroad.
Some of these furnaces combine several of the conventional proc-
ess steps. In addition, these alternative processes usually
generate lesser quantities of fugitive emissions, and for this
reason each may be considered also as a means of additional air
pollution control.
The alternative processes, however, do not eliminate fugi-
tive emissions. As in the foregoing description of conventional
smelting processes, this section briefly describes the operation
of these units and the points at which fugitive emissions occur.
The discussion includes the Noranda furnace, the electric fur-
nace, flash smelters (Outokumpu and Inco), and the Hoboken con-
verter .
NORANDA FURNACE
In the Noranda continuous furnace (Figure 10), the roast-
ing, smelting, and partial converting reactions are combined in
a vessel similar to a lengthened Peirce-Smith converter. One
U.S. plant started operating Norandas within the past year. The
reactor is a horizontal, cylindrical furnace about 21 m long.
It is fired from both end walls, and oxygen-enriched air is
blown into the matte layer through side-mounted tuyeres. The
furnace can be rotated on its horizontal axis to bring the
tuyeres out of the bath and stop the smelting process. The
compact design facilitates process control, and the domestic
Noranda smelter is highly instrumented. The Noranda was orig-
inally developed as a one-step process that would eliminate the
converter, thus significantly reducing capital costs and elim-
inating the need for a converter aisle. In U.S. commercial
applications to date, however, the Noranda is used with a con-
verter to allow greater production, better control of trace
elements, and longer life of the reactor lining.
20
-------
FEEDER
SO?
OFF-GAS
CONCENTRATE
PELLETS AND FLUX
HOOD
iiimiiiiiiiiiiiiiiiiiuiiiiniiiiiii^ BURNER
5SLAGE22SSE5
SLAG SETTLING
•*' "• * -"~ '
3
SLAG
AIR TUYERE , REDUCING GAS
HIGH-GRADE MATTE
Figure 10. Noranda continuous smelter.
21
-------
Operation
Concentrate and fluxes are fed to the Noranda by a slinger
at one end wall that spreads pelletized feed over the molten
bath. High-grade matte, which typically contains about 70
percent copper, is periodically tapped from the side of the
furnace and transported by ladles to standard Peirce-Smith
converters, where it is batch-treated to remove additional
sulfur and iron prior to fire refining. Slag containing 6 to 8
percent copper is periodically tapped from the end of the vessel
opposite the slinger. The slag is upgraded by milling to pro-
duce a concentrate, which is returned to the reactor, and. a
tailing, which is discarded. The off-gases leave the Noranda
furnace through its mouth, where they are captured by water-
cooled hoods and ducted to a waste heat boiler. The gases are
passed through cyclones and electrostatic precipitators to
remove particulate matter, and then used as feed to a sulfuric
acid plant. With 30 percent oxygen enrichment, the off-gases to
the acid plant contain 5 to 6 percent S02. The S02 concentra-
tion is approximately 4 percent without oxygen enrichment.
Emissions
If uncontrolled, fugitive emissions evolve from the follow-
ing areas around a Noranda smelting furnace: between primary
uptake hood and furnace mouth; from the mouth when in the rolled
out position; around matte and slag holes during tapping; and at
the port for feeding concentrate and fluxes.
ELECTRIC FURNACE
The electric copper smelting furnace (Figure 11) has been
used traditionally in Scandinavian areas where hydroelectric
power is cheap and fossil fuels are expensive. The first such
furnace in the United States started operation in 1972; two more
smelters have since adopted this technology.
The electric furnace is rectangular in cross-section with a
firebrick sprung-arch roof. The largest furnaces are about 35 m
long and 10 m wide. Carbon electrodes are placed in the molten
slag, and the heat required for smelting is generated by elec-
trical resistance of the slag to the submerged arc between elec-
trode pairs. Electrical ratings range as high as 51,000 kVA.
The chemical and physical changes that occur in the molten bath
are somewhat similar to those that occur in a reverberatory
furnace. The reverberatory furnace with a waste heat boiler is
more efficient than the electric smelting furnace.1
22
-------
OFF-GAS
ELECTRIC
FETTLING PIPES P°WER
ELECTRODES
CONVERTER
SLAG
LAUNDER
MATTE
CALCINE
SLAG
Figure 11. Electric smelting furnace.
23
-------
Operation
The charge of concentrate and fluxes is delivered to the
roof of the furnace by drag conveyors and then fed to the molten
bath through multiple-feed spouts near the electrodes and
between the sidewalls. As the charge materials melt, they
settle into the bath and form additional matte and slag.
Separate launders or chutes on the furnace end wall are used to
charge converter slag and reverts. Matte is tapped into ladles
from tap holes placed in the hearth area near one end wall.
Slag is skimmed from tap holes in the opposite end wall and
delivered by launders into slag pots, which are usually hauled
to a dump by trucks.
Although originally designed as an alternative to the use
of expensive fuels in Scandinavian countries, the electric
furnace also facilitates air pollution control. Because it does
not require large amounts of combustion air, the volume of
outlet gases is about an order of magnitude less than those from
a reverberatory furnace. Sulfur dioxide concentrations of 2 to
4 percent can be expected, and particulate emissions should be
lower than from a reverberatory because of the lower gas volume
and more uniform gas flow. The electric furnace off-gas at all
three domestic smelters is combined with other high-S02 gas
streams and fed to contact sulfuric acid plants.
Emissions
Fugitive emissions around electric arc furnaces are lower
than those from most reverberatory furnaces. For example, the
electric arc furnace at the Anaconda smelter in Montana has
tight brickwork, which prevents the leakage of fugitive emis-
sions from the sides of the smelter; with poor maintenance,
however, the brickwork could be a source of emissions. Where a
hooding system is used ineffectively over the slag ladle
during slagging, emissions will occur.• Other sources of fugi-
tive emissions are matte tapping, the converter slag return
launder, around the electrodes, and the calcine handling system.
FLASH SMELTING SYSTEMS
A recent development in copper metallurgy is the continuous
flash furnace, which is more efficient in terms of energy con-
sumption and also produces a more easily controlled stream of
flue gas than the reverberatory or electric furnaces. Flash
furnaces are of two types, the Outokumpu Oy and the Inco, which
differ primarily in their use of either preheated air or commer-
cial-grade oxygen to sustain the smelting reaction. The flash
furnace is in widespread use throughout the world, although only
one is operating in this country, under license from Outokumpu.
24
-------
The Outokumpu Furnace
The Outokumpu furnace (Figure 12) combines the functions of
roasting, smelting, and partial converting in a single furnace
with three sections—reaction shaft, settler, and uptake shaft.
Dried ore concentrates are injected continuously along with flux
and preheated air into the reaction shaft through concentrate
burners. Oil may also be injected into the shaft. The finely
divided concentrate burns in a "flash" combustion as the par-
ticles fall down through the shaft, and the heat released from
the combustion of the oil and sulfur sustains the smelting reac-
tion. The process is similar to the combustion of pulverized
coal. The molten particles fall into the settler part of the
furnace and separate into matte and slag layers. The matte,
which contains 45 to 75 percent copper, is tapped from the set-
tler and transferred to converters for further processing. The
slag, which contains too much copper to discard, is also proc-
essed further in an electric furnace. From the electric furnace
the copper containing-material from the slag is sent to the
Peirce-Smith converter. The slag from the electric furnace is
then dumped. Outlet gases from the Outokumpu furnace are con-
veyed from the uptake shaft. They contain 10 to 20 percent S02
and considerable quantities of entrained particulate matter.
The gases are cooled in a waste heat boiler, cleaned of particu-
lates in an electrostatic precipitator, and then sent for sul-
furic acid production.
Fugitive emissions from operation of the Outokumpu furnace
can occur at the launders and ladles and from leakage through
the furnace walls and roof.
The Inco Smelter
The Inco smelter (Figure 13) is similar to a reverberatory
furnace except that the off-gases are discharged at the center
of the furnace. The dry ore concentrate and fluxing agents are
injected into the furnace through both end walls, and oxygen is
also injected through both end walls. Fine particles are dis-
persed into the furnace, and flash combustion of the sulfides
creates the heat required for the smelting. The molten matter
falls on the molten bath, again forming a matte and a slag
layer. Charging is continuous. The slag, of high copper con-
tent, is treated for copper recovery. The matte grade is higher
than that of matte from the reverberatory furnace. The volume
of off-gases decreases as oxygen enrichment is utilized. Fugi-
tive emissions from the Inco smelter can occur at the launders
and ladles, and by leakage from the furnace sides, roofs, and
off-take.
25
-------
PREHEATED
AIR
OFF-GAS
SLAG
MATTE
SLAG
SETTLER
Figure 12. Outotun^i fUsh smelting furnace.
26
-------
CHALCOPYRITE
SAND CONCENTRATE
OFF-GAS
CONSTANT
WEIGHT FEEDERS
OXYGEN
OXYGEN
PYRRHOTITE, CHALCOPYRITE
CONCENTRATES, AND SAND
OXYGEN
SLAG MATTE
Figure 13. INCO flash smelting furnace.
27
-------
HOBOKEN CONVERTER
The Hoboken converter, shown in Figure 14, is an alterna-
tive to the Peirce-Smith converter. The Hoboken was designed to
largely eliminate the problem of excess air infiltration into
the flue gas off-take system. First developed in the early
1930's in Belgium, a Hoboken has been operated at a single
domestic primary smelter for about 4 years; Hobokens are also
installed at a number of copper plants in six foreign countries.
The Hoboken converter is similar to the Peirce-Smith, but
is equipped with an integral side flue at one end of the furnace
for withdrawal of the off-gas. Shaped like an inverted f'U",
this flue, or siphon, rotates with the converter, as does the
cylindrical duct to which it is connected. A counterweight
balances the siphon. The cylindrical duct is connected by an
airtight rotating joint to a fixed vertical duct that leads to
the gas cleaning system. The Hoboken thus provides a direct
link at all times between the converter and the gas off-take,
regardless of its operating position.
The Hoboken converters at the U.S. smelter in Inspiration,
Arizona, are 4.3 m in diameter by 11.6 m long. Each converter
has fifty-two 3.8 cm diameter tuyeres; air blast is approxi-
mately 31,500 Nm3/h.
Operation
Matte from the electric furnace at the Inspiration plant is
charged into one of the refractory-lined Hoboken converters.
When the converter is in the blowing position, the tuyere line
is 20 to 25 cm below the bath level, as with the Peirce-Smith.
To operate as designed, the draft at the mouth should be main-
tained at zero or a slightly negative draft; the design concept
is that emissions will not escape the mouth of the converter in
this operating mode but will be ducted to the end-mounted flue.
At Inspiration, temperature of the gas stream in the siphon
area of the Hoboken converter is 950° to 1100°. Gases contain-
ing S02 from the converter are combined with the gas stream from
the electric furnace and are sent to the acid plant after cool-
ing and particulate removal. So that flow of S02-containing gas
to the acid plant can be maintained, at least one converter must
always be in the blowing phase. A continuous stream of hot gas
through the duct system also minimizes condensation.
Charging, blowing, slagging or skimming, and pouring of
blister copper pouring are very similar to operations with the
Peirce-Smith converter. A Hoboken converter ready to come
on-line is heated and then charged with matte. The matte is
poured from a ladle, which is held and tilted by the EOT crane
28
-------
SIPHON
MOUTH
COUNTER-
WEIGHT
DROP OUT
CHAMBERS
Figure 14. Hoboken converter.
29
-------
hooks, into the rolled-out converter. The initial charge con-
sists of several ladles of matte. After flux is charged, the
air blast is turned on to begin the slag blow. The bath is
blown for 45 minutes to 1 hour, then the blow air is turned
down, the converter is tilted, and slag is poured off into a
ladle positioned on the floor of the converter aisle. After one
or two ladles of slag are poured, a similar amount of matte is
charged to the converter. When in the upright position, the
converter is blown again to further burn off the sulfur combined
with the iron, and allow the iron oxide that is formed to react
with the flux to produce slag. The off-gas stream containing
the sulfur oxidized during blowing is pulled through the siphon
to the uptake duct, then sent to an acid plant. At the Inspira-
tion plant, slag is poured off and transferred in ladles via the
EOT crane and charged into the electric smelting furnace for
recovery of the copper.
As with the Peirce-Smith converter, the slag blow is fol-
lowed by the blister copper blow. The copper sulfide bath is
blown until all or nearly all of the sulfur is burned off,
mainly oxidized as S02. Upon completion of the copper blow, the
product is blister copper. It is poured into ladles that are
carried by the EOT crane to the anode furnace.
Emissions
One major difference between the Hoboken and Peirce-Smith
converters is that the Hoboken is not equipped with a primary
uptake hood over the mouth, but rather with the siphon and
side-mounted flue. Any emissions that escape the mouth are
fugitive emissions.
A properly designed, operated, and maintained Hoboken con-
verter (such as the one operated by Hoboken Overpelt in Belgium)
generates only minimal fugitive emissions, even though the mouth
is not hooded, because the converter is operated under zero or
slightly negative draft. At slight negative draft, air from
outside of the converter is sucked into the mouth and exits
through the converter siphon with the gas stream containing the
S02 generated during blowing. Air brought into the converter in
this manner cools the discharge gas stream and dilutes the S02
in the off-gas stream, but this dilution can be minimized.
Slight negative or zero draft prevents fugitive emissions from
the mouth of the converter.
The small amounts of fugitive emissions from a Hoboken
converter usually occur during charging of matte or cold mate-
rial or during slagging or blister copper pouring. During these
operations, the converter is rolled out and the blowing air is
turned down, but the zero or slightly negative draft is main-
tained. During matte charging, some emissions are released from
30
-------
the hot metal stream as it flows from ladle to furnace. Emis-
sions during slagging and blister copper pouring occur in a
similar manner.
In summary, a Hoboken converter that is well designed,
installed, operated, and maintained generates small quantities
of fugitive emissions. The addition of a swing-away hood
(Figure 15) would minimize emissions during slagging or pouring.
During the blowing periods, fugitive emissions are controlled to
a much greater degree than with the Peirce-Smith converter.
No characteristics or analyses of fugitive emissions are
available.
31
-------
to
CAPSTAN
LIFT
DEVICE
TO FUGITIVE
EMISSION
COLLECTOR
ttt
• 1 '
ll
I
SWIVEL
JOINT
Figure 15. Hoboken converter with swingaway hood.
-------
SECTION 5
SUMMARY OF FUGITIVE EMISSIONS FROM COPPER SMELTERS
In efforts to determine typical quantities of fugitive
emissions from copper smelters, the authors consulted the tech-
nical literature and undertook an inquiry by telephone with
knowledgeable persons in the copper industry and in government.
The literature search indicated a minimal amount of valid pub-
lished data on process rates, emission rates, and emission
characteristics. In the course of the inquiry we learned of no
actual published measurements of fugitive emissions from rever-
beratory furnaces, converters, or other process equipment at
copper smelters.
We have therefore prepared a set of emission estimates
corresponding to several arrangements of process equipment,
summarized in Table 1. For each combination of process equip-
ment the emission estimates are based on maintaining the same
production rate, 303 tons of blister copper per day. The emis-
sion values are based on data from several sources, primarily
reports (References 2 and 3) and conference presentations
(References 4 and 5). Reference 2 was the principal source of
the emission estimates. Data from all of the sources have been
modified to accommodate the selected production rate and thus
allow comparison among the several process arrangements.
Figures 16 through 27 depict material balances for each of
the equipment items listed in Table 1. Each figure is intended
to approximate the material balance that would occur when the
equipment is operated in the specific combination designated in
Table 1. Thus, although the Peirce-Smith converter is a com-
ponent of each of the five equipment combinations in the table,
the materials entering the converter depend upon the equipment
that precedes it in the smelting process; e.g., matte entering
the converter from a reverberatery furnace (Figure 18) contains
greater quantities of sulfur, iron, and other materials than
matte from the Outokumpu furnace (Figure 24). The emission
estimates of Table 1 reflect these differences and thus provide
an indication of the relative magnitude of emissions under
various process arrangements.
33
-------
TABLE 1. ESTIMATED FUGITIVE EMISSIONS FROM COPPER SMELTING
IN VARIOUS PROCESS ARRANGEMENTS
1.
2.
3.
4.
5.
Multi hearth roaster (Fig. 16)
Reverberatory furnace (Fig. 17)
Peirce-Smith converter (Fig. 18)
Fluid-bed roaster (Fig. 19)
Reverberatory furnace (Fig. 20)
Peirce-Smith converter (Fig. 21)
Noranda furnace (Fig. 22)
Peirce-Smith converter (Fig. 23)
Dryer
Outokumpu furnace (Fig. 24)
Peirce-Smith converter (Fig. 25)
Dryer
Electric furnace (Fig. 26)
Peirce-Smith converter (Fig. 27)
Estimated Fugitive Emissions
S02a
c
4.2
6.5
c
4.2
6.5
2.9
1.5
c
2.9
2.1
c
3.0
6.5
Cub
c
0.16
0.16
c
0.16
0.16
0.11
0.03
c
0.15
0.03
c
0.15
0.19
Feb
c
0.10
0.21
c
0.09
0.21
0.07
0.33
c
0.15
0.38
c
0.07
0.21
Others5
c
0.10
0.11
c
0.12
0.13
0.04
0.12
c
0.07
0.08
c
0.04
0.06
Percentage of sulfur charged to the process equipment, expressed as S02.
Percentage of the total copper, iron, or other materials charged to the
process equipment.
No values available.
34
-------
FEED
Cu
Fe
s
SO
CO
2
2
383.
53.
0
5
(54
(7.
.8)
6)
7.0% VOL. SiO?
CaO^
nthpr
308
308
382
102
5.
34
7
•
6
6
9
9
2
(44
(44
(54
(14
(0.
(4.
.1)
.1)
.7)
.7)
8)
9)
FLUX
CaO
SiO?
C02
Other
49.0
97.1
37.3
12.2
(7.0)
(13.9)
(5.3)
(1.7)
HOT AIR
TO EXHAUST
RABBLE
ARM
RABBLE
BLADE
A FUGITIVE
\ EMISSIONS:
)MO VALUES
/AVAILABLE
AIR:
02
C02
191.5
16.2
(27.4)
(2.3)
NATURAL
GAS
CALCINE
COOLING
AIR
MATERIAL BALANCE IN TONS/DAY.
NUMBERS IN PARENTHESES INDICATE
CAPACITY OF EACH UNIT.
OTHER VALUES ARE BASED ON 303
TONS/DAY OF BLISTER COPPER.
Cu
Fe
S
SiO?
CaO
Other
308.6
308.6
191.4
200.0
54.7
46.4
(44.1)
(44.1)
(27.3)
(28.6)
(7.8)
(6.6)
Figure 16. Material balance: multibearth roasting furnace.
35
-------
U)
S
Cu
Fe
SiO?
CaO
02
Other
3.7
12.0
239.1
115.2
5.0
69.2
6.9
00 1103.8
Cu
Fe
S
SiO~
CaO
Other
308.6
308.6
141.4
200.0
54.7
46.4
CALCINE
FUEL
INVERTER
SLAG
AIR AND -SZ
OXYGEN
BURNERS
FUG]
SO?
Cu
Fe
S
TJVES
B.T
0.5
0.5
0.2
OFF-GAS
so2
1
14
.7
1
VOL. %-
MATTE
SLAG
CHARGING PIPES
MATERIAL BALANCE IN TONS/DAY
ALL VALUES ARE ON BASIS OF 303 TONS/DAY
OF BLISTER COPPER (SLIGHTLY BELOW
CAPACITY OF UNIT).
MATTE
Cu
Fe
S
CaO
00
2
315.5
238.5
126.6
3.7
47.7
Cu
Fe
S
Si09
CaO
02
Other
4.6
308.7
6.8
315.2
56.0
63.7
53.1
Figure 17. Material balance: reverberatory furnace after multihearth roaster.
-------
MATTE
Cu
Fe
S
CaO
°2
315.5
238.5
126.6
3.7
47.7
(129.3)
(97.7)
(51.9)
(1.5)
(19.5)
SLAG
so2|
237.0
(97.2)
4% VOL.
OFF-GAS
TUYERE
PIPES
SO-
Cu^
Fe
S
FUGITIV
8.2
0.5
0.5
0.2
ES
(3.4)
(0.2)
(0.2)
(0.1)
Fe
Si Op
CaO
02
Other
2.6
115.2
1.3
0.7
8.2
(1.1)
(47.2)
(0.5)
(0.3)
(3.4)
Cu
Fe
S
Si09
CaO
02
Other
12.0
239.1
3.7
115.2
5.0
69.2
6.9
(4.9)
(98.0)
(1.5)
(47.2)
(2.0)
(28.4)
(2.8)
TnU
PNEUMATIC /-»
PUNCHERS *^
BLISTER COPPER
Cu
Fe
Other
303.0
1.5
1.5
(124.2)
(0.6)
L (0.6)
AIR
°2
[143.3
(58.9)
MATERIAL BALANCE IN TONS/DAY.
VALUES IN PARENTHESES INDICATE CAPACITY
OF UNIT; OTHER VALUES ARE ON BASIS OF
303 TONS/DAY BLISTER COPPER.
Figure 18. Material balance: Peirce-Smith converter after reverb and multihearth.
-------
FEED
Cu
Fe
S
Si09
CaO
Other
308.6
308.6
382.9
102.9
5.7
34.2
oo
CO
FLUX
CaO
Si09
C02
Other
49.0
97.1
37.3
12.2
FUGITIVE
EMISSIONS;
NO VALUES
AVAILABLE
OFF-GAS
TUYERE
HEADS
&
v/Uo
127.9
1.7
SOo
CO^
255.8
39.0
13% VOL.
MATERIAL BALANCE IN TONS/DAY.
TONNAGES ARE FOR CAPACITY OF UNIT
Cu
Fe
S
Si 0/>
CaO
Other
308.6
308.6
255.0
200.0
54.7
46.4
Figure 19. Material balance: fluid-bed roaster.
-------
U>
CONVERTER
SLAG
Cu
Fe
S
Si09
CaO^
02
Other
12.0
240.0
5.0
115.2
5.0
91.2
7.8
Cu
Fe
S
SiO~
CaCT
Other
308.6
308.6
255.0
200.0
54.7
46.4
CALCINE
FUEL
CONVERTER
SLAG
AIR AND
OXYGEN
°2
139.2
BURNERS
FUGITIVES
SO,
Cu<
Fe
S
10.8
0.5
0.5
0.3
MATTE
SLAG
CHARGING PIPES
MATERIAL BALANCE IN TONS/DAY.
TONNAGES ARE FOR CAPACITY OF UNIT.
OFF-GAS
MATTE
S02 1153.0
1% VOL.
Cu
Fe
S
SiO?
CaO^
Other
308.6
308.6
255.0
200.0
54.7
46.4
Figure 20. Material balance: reverberatory furnace after fluid-bed roaster.6
-------
MATTE
Cu
Fe
S
CaO
°2
315.5
238.5
168.7
3.7
63.4
(119.8)
(90.6)
(64.1)
(1.4)
(24.1)
SLAG
FUGITIVES
so
2
31
6
.0
(1
20
.0)
4%
VOL.
TUYERE
PIPES
SQ0
Cu4-
Fe
S
11.0
0.5
0.5
0.2
(4.2)
(0.2)
(0.2)
(0.1)
Fe
Si09
CaO^
°2
Other
2.6
115.2
1.3
0.7
8.2
(1.0)
(43.8)
(0.5)
(0.3)
3.2
S
Cu
Fe
SiOp
CaO^
02
Other
5.0
12.0
239.1
115.2
5.0
91.2
6.9
(1.9)
(4.6)
(90.8)
(43.8)
(1.9)
(34.6)
(2.6)
7^
PNEUMATIC /^fe
PUNCHERS *%Ł
BLISTER COPPER
Cu
- Fe
Other
303.0
1.5
1.5
(115.0)
0.6
(0.6)
°2
190.8
(72.3)
MATERIAL BALANCE IN TONS/DAY.
VALUES IN PARENTHESES INDICATE CAPACITY
OF UNIT; OTHER VALUES ARE ON BASIS OF
303 TONS/DAY BLISTER COPPER.
Figure 21. Material balance: Peirce-Smith converter after fluid-bed and
reverberatory furnace."
-------
FLUX
Fe 11.
S 2.
Si02 181.
PELLETIZED
CONCENTRATES
Cu 357.7 (431.7)
Fe 395.7 (477.6)
S 421.9 (509.2)
Si02 67.6 (81.6) FEEDER
02 331.5
7 (14.1)
4 (2.9)
6 (219.2)
SO~2J650~.7 (785.4) 6% VOL.
SQ2 FUGITIVES
Ohh-bAb ' "
CONCENTRATE / t \ ^°2 1?'?
i>f PELLETS AND FLUX / \HOOD Cu 0.4
w \ \ Fp n-*
rŁ m "*^ L%s> R S 0.3
VTt j-«miiiiiiiiiiiiiiiiiiiiiiiiiuiiiiiiiiniy- •Ulllllllllllllllllllllllllinllllimmi 1 nilDMrn
"* § -T^*^5^^- :,••.-. SETTLING c, Ar 7TTT1 TNr Ł
— '**^i'r*~^*'1~ptif?Lrtf^''r\~— OLnu OL 1 L L A1113 Bt -^^
AIR TIIYFRE ~~\^ Ffi 398.7
M1K IUTtKt ' REDUCING GAS ^ -|n q
(400.1) HIGH-GRADE MATTE Si°2 249'2
(14.8)
(0.5)
(0.4)
(0.4)
(51.0)
(481.2)
(12.4)
(300.8)
Cu 315.0 (380.2)
Fe 8.4 (10.1)
S 82.2 (99.2)
MATERIAL BALANCE IN TONS/DAY.
VALUES IN PARENTHESES INDICATE CAPACITY
OF UNIT; ALL OTHERS ARE ON BASIS OF
303 TONS/DAY BLISTER COPPER.
Figure 22. Material balance: Noranda continuous smelter.
-------
MATTE'
Cu
Fe
S
315.0
8.4
82.2
(233.0)
(6.2)
(60.8)
NO
so2
159.0
(117.5)
4% VOL.
FUGITIVES
SLAG
TUYERE
PIPES
SO-
Cu
Fe
S
1.2
0.1
0.005
0.1
(0.9)
(0.1)
(0.004)
(0.1)
SiO,
Fe Z
Other
25.5
0.6
2.3
(18.9)
(0.4)
(1.7)
Cu
Fe
S
SiO?
OthSr
11.9
7.5
2.0
25.5
0.8
(8.8)
(5.5)
(1.5)
(18.9)
(0.6)
/AVJi
PNEUMATIC /*Ł
PUNCHERS Mg?
^v
BLISTER COPPER
Cu
Fe
Other
303.0
1.5
1.5
(224.1)
(1.1)
(1.1)
°2
80.1
(59.2)
MATERIAL BALANCE IN TONS/DAY.
VALUES IN PARENTHESES INDICATE CAPACITY
OF UNIT; OTHER VALUES ARE ON BASIS OF
303 TONS/DAY BLISTER COPPER.
Figure 23. Material balance: Peirce-Smith converter after Noranda furnace.
-------
u>
DRIED
CONCENTRATES
FUGITIVES
SO,
Cu^
Fe
S
14.5
0.5
0.7
0.6
S
Fe
Cu
SiO~
Ni e-
Other
499.6
467.6
330.6
64.1
1.6
93.1
AIR |
09 393.8
<-
^
\
\
jr —
FLUX
Si02
Fe
Ni
Other
205.7
8.1
2.3
177.6
HIGH-GRADE
MATTE
Cu
Ni
Fe
S
Other
315.0
3.5
25.5
89.1
8.4
OFF-GAS S02 773.1
(10% VOL.)
SLAG
MATTE
SLAG HATTE
SETTLER
MATERIAL BALANCE IN TONS/DAY.
VALUES INDICATE CAPACITY OF UNIT.
Cu
Ni
Fe
S
SiO?
Other
15.1
0.4
449.5
16.1
269.8
262.3
Figure 24. Material balance: Outokumpu flash smelting furnace.
-------
MATTE
Cu
Ni
Fe
S
Other
315.0
3.5
25.5
89.1
8.4
(214.0)
(2.4)
(17.3)
(60.5)
(5.7)
SLAG
TUYERE
PIPES
S
Cu
Fe
SiOp
Ni 2
Other
2.3
11.9
24.8
35.6
3.5
10.1
(1.6)
(8.1)
(16.7)
(24.2)
(2.4)
(6.9)
so2
171
.5
(116
.3)
4%
VOL.
FUGITIVES
S00
Cu^
Fe
S
1.9
0.1
0.01
0.1
(1.3)
(0.1)
(0.01)
(0.1)
Fe
SiO?
Other
0.8
35.6
3.2
(0.5)
(24.2)
(2.2)
BLISTER COPPER
Cu
Fe
Other
303.0
1.5
1.5
(205.8)
(1.0)
(1.0)
°2
86.7
(58.8)
MATERIAL BALANCE IN TONS/DAY.
VALUES IN PARENTHESES INDICATE CAPACITY
OF UNIT; OTHER VALUES ARE ON BASIS OF
303 TONS/DAY BLISTER COPPER.
Figure 25. Material balance: Peirce-Smith converter after Outokumpu furnace.1
-------
DRIED
CONCENTRATES
Cu
Fe
S
Si 09
Ca(T
Other
308.6
308.6
379.1
102.9
5.7
38.4
(404.9)
(404.9)
(497.4)
(135.0)
(7.5)
(50.4)
FUGITIVES
S00
Cu"
Fe
S
11.6
0.5
0.5
0.3
(15.2)
(0.7)
(0.7)
(0.4)
CONVERTER
SLAG
*»
Ul
OFF-GAS
9
so2
238.
0
(310.
2)
5%
VOL.
Cu
Fe
S
Si 09
CaO^
Other
18.9
372.9
7.7
179.4
7.8
154.0
(24.8)
(489.2)
(10.1)
(235.4)
(10.2)
(202.0)
ELECTRIC
FETTLING PIPES POWER
ELECTRODES
CONVERTER
SLAG
LAUNDER
MATTE
CALCINE
Cu
Fe
S
CaO
Other
322.5
371.2
253.5
5.8
61.0
(432.1)
(487.0)
(332.6)
(7.6)
(80.0)
MATERIAL BALANCE IN TONS/DAY.
VALUES IN PARENTHESES INDICATE CAPACITY
OF UNIT; OTHER VALUES ARE ON BASIS OF
303 TONS/DAY BLISTER COPPER.
FLUX
Si Op
CaO
C02
Other
32.9
48.0
37.3
9.0
(43.2)
(63.0)
(48.9)
L(11.8)
SLAG
Air
°2
123
.9
(162
.7)
Cu
Fe
S
Si Op
CaO^
Other
4.5
309.8
9.1
315.1
55.7
140.4
(5.9)
(406.4)
(11.8)
(413.6)
(73.1)
(184.2)
Figure 26. Material balance: electric smelting furnace.'
-------
MATTE
Cu
Fe
S
CaO
Other
332.5
371.2
253.5
5.8
61.0
(95.4)
(109.8)
(75.0)
(1.7)
(18.0)
TUYERE
PIPES
SLAG
Cu
Fe
S
SiO?
CaO
Other
18.9
372.9
7.7
179.4
7.8
154.0*
(5.6)
(110.4)
(2.3)
(53.1)
(2.3)
(45.6)
so2
474.5
(140.3)
3.5% VOL.
FUGITIVES
S00
Cu*-
Fe
S
16.5
0.6
0.8
0.3
(4.9)
(0.2)
(0.2)
(0.1)
^Contains 02 80.4 (23.8)
325.9
BLISTER COPPER
96.4)
Cu
Fe
Other
303.0
1.5
1.5
(89.6)
(0.4)
(0.4)
MATERIAL BALANCE IN TONS/DAY.
VALUES IN PARENTHESES INDICATE CAPACITY
OF UNIT; OTHER VALUES ARE ON BASIS OF
303 TONS/DAY BLISTER COPPER.
Fe
Si 09
CaO^
Other
4.0
179.4
2.0
14.1
^1.2)
(53.1)
(0.6)
(4.2)
Figure 27. Material balance: Peirce-Smith converter after electric furnace.1
-------
SECTION 6
CURRENT CONTROLS AND PROPOSED MODIFICATIONS
Control of fugitive emissions at copper smelters currently
consists of application of certain fundamental control prin-
ciples, such as preventive maintenance, use of hooding, and
installation of emission collection systems at various stages of
the process.
Most plants schedule periodic maintenance of major equip-
ment and perform repairs as needed to correct malfunctions. In
addition to these practices, preventive maintenance would in-
volve close attention throughout the daily plant operations to
detect potential problems and to remedy defects as they occur.
The goal is to prevent catastrophic malfunction or upset, which
not only can retard or completely curtail production, but also
can cause the release of large quantities of fugitive emissions.
Programs of preventive maintenance should be geared specifically
to the specific type of plant equipment, with emphasis on pre-
vention or leakage from roasters and furnaces through attention
to the condition of refractories, tight fit of doors and covers,
and all other areas of the unit that might allow leakage.
The following types of emission collection systems are in
current use, either singly or in various combinations:
Fixed secondary hoods
Swingaway and movable secondary hoods
Converter aisle forced-exhaust system with baghouse (i.e.,
enclosed building)
Air curtains
Roof monitors.
Table 2 briefly describes the design and operation of each of
these systems and lists the typical operating and maintenance
problems that are encountered. Appendix B discusses air curtains.
Some smelters have introduced innovative control equipment
and procedures, and other control strategies are proposed and
under investigation. In addition to descriptions of the common
47
-------
TABLE 2. SUMMARY OF CURRENT FUGITIVE EMISSION CONTROL SYSTEMS
Type
Design and operation
Operational and maintenance problems
Efficiency
00
Monitor, natural
(U.S.)
Monitor, powered
Fixed hood with
secondary emission
ducting (U.S.)
Enclosed converter
hood swing-away type
with fixed hood
Enclosed building
Simple design; relies on outside
air movement for removal of emis-
sions
Simple design; large air movement
required at fans; removal rate is
constant
Clearance needed for crane hook and
cables during collar pulling or matte
additions; retrofit difficult for
ducting, fans, breeching, and dust
bins; operational at all times that
converters are on line; good face
and capture velocities required.
Clearance needed for crane hook and
cables during collar pulling or
matte additions (fixed hood). Clear-
ance needed for floor space relative
to fixed hood; rugged drive mecha-
nism needed for swing-away converter
hood
Requires careful design of all open-
ings (personnel, truck, rail, mate-
rials) to minimize air motion; roof
monitor must handle all ventilation
air for workers; building costs high
because of wind load design and need
for tightness and close fits
Haze in building during emissions; outside air movement
affects time required to clear the area; crane operator
and maintenance personnel working above the converter
may be required to wear face aspirators; visible emis-
sions in the monitor area; maintenance in the converter
area; EOT and roof trusses for removal of the settled
emissions other than gases.
Blind pockets or short-circuited flows could cause haze
and emission buildup in the roof line area; crane oper-
ator may need to wear face aspirator at times; main-
tenance in converter area, EOT crane, and roof trusses
for removal of settled emissions other than gases.
Operational damage to hood by swinging or uncontrolled
EOT crane action during matte addition or collar pull-
ing; maintenance is less in the converter area, EOT
crane, and roof trusses
Space occupied in aisle by the swing-away converter hood
when adding matte, rabbling, or skimming could hamper
crane movements; crane must deposit ladles for pouring
or skimming and at completion of the operation must
await retraction of the hood before engaging the ladle;
maintenance of swing-away mechanism and minimal main-
tenance for removal of particulate buildup that occurs
during matte additions and rabbling
All openings must be maintained constantly against ex-
cessive air infiltration; light siding and roofing
required; air circulation within building for the
workers and process must be carefully controlled;
intake and exhaust fans need preventive maintenance;
cleanup maintenance for settled particulates in the
converter area is similar to that for a monitored
system, either natural or powered.
Dependent on outside air
currents and inside air
motion
Dependent on number of
monitors, fan size, build-
ing design above the con-
verter proper; air motions
Dependent on distance of the
mouth of fixed hood from the
emission source; also on
capture and face velocity
created by the fan at mouth
of fixed hood.
Dependent on operational
cycle; efficient during
pouring, blowing, or slag-
ging; efficiency similar to
that of fixed hood during
matte addition or rabbling;
air motions influence ef-
ficiency in all operations
Dependent on building tight-
ness, air motion control,
monitor exhaust capabilities
-------
controls in current use at copper smelters, this discussion
presents suggested modifications and control measures that could
further reduce fugitive emissions. Emphasis is placed on The
Peirce-Smith converter, a significant source of uncontrolled or
poorly controlled fugitive emissions.
HOODING SYSTEMS
Emissions of sulfur dioxide and particulate from copper
smelting are contained to some extent by hooding systems. All
of the domestic smelters are equipped with primary hoods, and
some also have various types of secondary hoods, which can be
very effective over reverberatory matte and slag launders. At
some smelters the slag ladles are operated within a partial
enclosure with a hood overhead to collect fugitives during slag
discharge. Swing-away hoods that are lowered to cover the matte
ladles during filling are used at some plants and are effective
while the ladle is being filled. When the filled ladle must be
removed from under this cover, however, fugitive emissions arise
from the matte surface.
Secondary hooding systems are being used also to partially
control fugitives from some Peirce-Smith converters. At some
smelters a fixed hood (Figure 28) located above the sliding gate
is used in conjunction with the primary hood during blowing
operations. Although it is somewhat effective during the blow-
ing phases, the hood serves little use in controlling fugitive
emissions when the converter is in the "rolled-out" position,
i.e., when the gate is in the upmost position and the converter
is pouring or receiving charge. Following are details of the
various hooding systems.
Fixed Secondary Hood
In the United States the Phelps Dodge Corporation has in-
stalled some fixed secondary hood units at their Ajo and Morenci
plants. The configuration of a fixed secondary hood depends on
the location of the converter relative to the crane runway gird-
ers, the configuration of the primary uptake hood, and the
requirements for maintenance and operation. The effectiveness
of a secondary emission control system is influenced con-
siderably by these factors. Air movement in the converter area
and the capture velocity at the face of the secondary hood are
also important.
At the Ajo Smelter, the atmosphere of the converter room
Is relatively cleanj the crane operator does not wear a face
respirator. Conditions of the converter aisles appear to be less
satisfactory at some of the other U.S. smelters not equipped with
fixed secondary hooding.
49
-------
TO SECONDARY
HOODING
MAIN DUCT
Figure 28. Secondary converter hood configuration,
50
-------
Figures 29 and 30 show the overall ducting (approximately
210 m) of the secondary emissions system at Ajo. Each converter
has two secondary inlets, one on each side of the primary hood.
Each fixed hood (Figure 28) is approximately 4 m long, 6 m
wide, and 2 m high. The hoods, which are half-oval in cross-
section, are affixed to the upper front sides of the converter
primary uptake hoods. Each secondary duct handles approximately
68,000 m3/h at temperatures of about 93°C.
Requirements at the Ajo plant cannot be regarded as appli-
cable to other smelters, whose layouts may necessitate different
quantities and configurations of ducting to contain fugitive
emission effectively.
Movable Hoods
Movable secondary hoods are used in conjunction with a
fixed hood at several primary copper smelters in the United
States.
A type of movable hood system that could be used for con-
trol of converter emissions is shown in Figures 31 through 34.
The movable hood would be made of steel, elliptical in shape so
as to fit over the fixed hood with a clearance of 10 to 15 cm.
It would have its own track for movement.
In the retracted position, the movable hood should not
extend farther horizontally than the fixed hood. In the
extended position, it would mate with the lip of the fixed hood
to provide continuity of ducting of secondary emissions. The
movable hood would have its own retracting and lowering mecha-
nisms, which would be controlled by the converter operator.
The hood attached to the gate also would be a type of mov-
able hood. The gate hood (Figures 33 and 34) would be of steel
construction and possibly elliptically shaped to fit under the
movable hood when in a retracted position. Again, as with the
movable hood, the gate hood would be protected by the fixed hood
in its up position, i.e. no part of the retracted gate hood
would extend horizontally beyond the fixed hood (Figure 34).
In the extended position, the gate hood would continue the
ducting of secondary emissions to the movable and fixed hoods.
Swing-Away Hood
A brochure of the Nippon Mining Company shows a deflector
converter hood of the swing-away type with a retractable second-
ary hood above (Figure 35). In the foreground, the deflector
hood is shown in the operating position during a blister copper
pour. The emissions are deflected into the retractable hood.
51
-------
en
K)
CONVERTER AISLE
MECHANICAL
CIVM/CT ur\An mifT Tf\ CTAPI/ MATPH 1 TNF
oMUKh HUUU UULI ID blALN imiun LIIML
PLAN & ELEVATION SHEET NO. 1
DUCI DC nnnrF rflDDODATTON
rntLro-UUUvat HJKrUKMI iUrl
NEW CORNELIA BRANCH AJO, ARIZONA
PLAN VIEW
O — ^ t i j^'iTJ1' 1 ""*" 'id'C"* 1 1 C3 C~y|~rT'^ *~ **}-!.- li})) S
DUCT
«..,_.,. ...... f T on ' \ APPDHY ... , ..........
55 m
DUCT
o e — i — x\j" r — *• i -—^1 1 ^<^ 1 — *• ^-.-J~ft — ^^ f~ "*• 17~"}x.
^^ fi^ ' /^^ RT ' /^^ >^^ /S^" "v^s
CL> ~-k I^J ^^j i^T 11^ it Pt *C>
"*• , \*
^CONVERTER il CONVERTER i- CONVERTER
'
-------
Ul
53.3 m
(175 ft) APPROX/
ELEVATION
MATCH LINE
a:
-
SECTION A-A
II—HI3
SECTION B-B
*>
SHELTER
KEY PUN
Figure 30. Ajo Smelter, secondary emission collection system, sheet 2 of 2.
-------
SMOKE PLENUM
SECONDARY DUCT
(LOCATION SHOWN IS FOR'
A LOW CRANE RUNWAY)
MOVABLE HOOD
INDEPENDENTLY OPERATED
AND TIED INTO
GATE MOVEMENT
SECONDARY DUCT
DUST BIN
TO COPPER
HEADER
TO FAN
SECONDARY DUCT
TO STACK
DAMPER CONTROL
INDEPENDENTLY
OPERATED
HOOD HOIST
MECHANISM
HOOD FIXED
TO GATE
BIN ON TAKE AWAY
Figure 31.
Side view of Peirce-Smith converter with hooding
in position.
54
-------
HOOD FIXED
TO GATE
r
CONVERTER
SECONDARY DUCT
DUST BIN
Figure 32. Front view of fixed, movable, and gate hoods.
55
-------
EOT RUNWAY
SECONDARY HOOD
DUST BIN
SECONDARY HOOD DUCT
SMOKE PLENUM
SECONDARY HOOD DUCT
SECONDARY HOOD DUST BIN
XDUST BIN
MAIN HOOD
SECONDARY
HOOD DUCT
MOVABLE HOOD
MOTORIZED DRIVE
SWING HOOD DURING
TAPPING OR SLAGGING
POSITION
LADLE
Figure 33. Peirce-Smith converter with hooding extended.
56
-------
HOIST DRUM
GEAR REDUCER
TO COPPER HEADER
TO FAN 7
E.O.T. CRANE
BRIDGE
^/_j*v \
&M/ ;
Ł'S/v-j\/7 <»
t'-.J^U^ C
SECONDARY DUCT
TO STACK
DAMPER CONTROL
NOTE:
INSTALL LIMIT SWITCH TO
TRAVEL OF TROLLY FOR
CHARGING OR COLLAR PULLING
TO PROTECT HOODING: FOR
OTHER MAINT. WORK, ETC.
REQUIRING THE HOOK TO WORK
IN THIS AREA THE LIMIT
SWITCH WILL ENERGIZE A GONG
AND FLASHING LIGHT TO ALERT
THE CRANEMAN AND CONVERTER
OPERATORS THAT THE LOAD ON
THE CRANE OR HOOK CAN
i INTERFERE OR DAMAGE THE
iOOD UNLESS THE HOODING
[S RETRACTED.
BIN OR TAKE AWAY
Figure 34. Side view of Peirce-Smith converter during collar pulling or
blister copper ladle removal, with hooding retracted.
57
-------
Figure 35. Enclosed swing-away converter hood of Nippon Mining Company.
58
-------
Movable hoods must be retractable to a position that does
not interfere with the overhead crane or plant operations and
that is not subject to abuse from moving objects, such as the
EOT crane hoist block or cables, charging ladles, or the
collar-pulling rig.
Some operating procedures and system design factors for
secondary hood systems are discussed below. These procedures
and designs should minimize damage, breakdowns, and delays and
should optimize working conditions for plant employees.
The movable, swing-away, and gate hoods should be under
control of the converter operator. The EOT crane operator and
converter personnel should be aware whenever the EOT crane hook,
cables, and hook load (ladle, collar puller, etc.) pass into the
area adjacent to the hoods as indicated at the Nippon plant in
Figure 35. At such times the trolley of the EOT crane could
trip a limit switch to energize an intermittent sounding horn
and/or flashing lights on the underside of the EOT crane cab
stairs. These warning signals would operate as long as the
trolley of the EOT crane is in the area of the hoods. The horn
signal should be of such intensity and sound as to be distin-
guishable from other EOT crane or maintenance sirens. Whenever
this sound is heard, one of the converter personnel would check
to see what hoods may need to be retracted.
At the end of each shift, the departing EOT crane operator
would check the warning or interlock system by a trial run of
the trolley into this converter area and record its condition on
his daily check list. Before putting the EOT crane into ser-
vice, each incoming crane operator would also check out the
warning system.
For matte additions and collar pulling procedures, the
converter operator would position the converter gate and retract
all the hoods. After the matte addition, the converter would be
rotated to its blowing position in the primary converter uptake
hood. All hoods would be extended into position; blowing would
commence, and flux could be added to the converter as required.
For slagging or skimming operations, the swing-away hood
would be retracted. In the event of interference between the
EOT crane hook or cables and the gate hood, the gate hood too
must be retracted. After the ladle is removed or repositioned,
the EOT crane would be backed off and the appropriate hoods
positioned in place. The same movements of the hoods would be
required in blister copper pouring for the positioning or
removing of a ladle.
Positions of the secondary hoods during the various con-
verter operations are shown in Table 3. Estimated efficiencies
of the different types and combinations of hoods during the
various converter operations are shown in Table 4. The valves
60
-------
TABLE 3. POSITIONS11 OF MOVABLE HOODS
Type
Movable
Gate hood
Swing- away
Matte
addition
Retracted
Retracted
Retracted
Blowing
or
holding
Extended
Extended
Retracted
or in
operating
position
Skimming
Extended
Extended
Operating
position
Rabbling
Partially or
fully extended
Partially ex-
tended
Retracted
Collar
pulling
Retracted
Retracted
Retracted
Pouring
Extended
Extended
Operating
position
Definitions of hood positions:
Retracted - hood in its highest or extreme position away from the converter.
Extended - hood in its lowest position.
Partially extended - hood extended as far as practical to maximize secondary emissions
control.
-------
KJ
TABLE 4. PEDCO'S ESTIMATED RETROFITTED HOODING EFFICIENCIES'
(values in percent)
Hood type
Fixed
Fixed and movable
Fixed and swing- away
Fixed, movable, and swing- away
Enclosed building
Matte
or
hot metal
addition
30-50
30-50
30-50
30-50
50c-95
Blister
or
hot metal
pouring
30-50
40-70
80-90
80-90
50c-95
Skimming
or
slagging
30-50
40-70
50-70b
60-80b
50c-95
Blowing
60-70
70-90
80-90
80-90
50c-95
Most system efficiencies would be higher if air motion (i.e., open doors, man-cooling fans,
monitors, etc.) could be eliminated. Skimming is removal of slag from the converter by
tilting of the converter. Slagging is removal of slag from the converter by tilting of the
converter and manual use of a rake to work the molten bath.
Efficiency during slagging would be similar to that in blister pouring.
c Low efficiency due to air motion; with inadequate design of monitors and airflow, efficiency
could be as low as 75%; with doors left open efficiency could drop to 50%.
-------
for collection efficiency are based on retrofit installations.
Collection efficiencies would be greater if the installation
were incorporated into design of a new plant.
ROOF MONITORS
The standard design in buildings where emissions can cause
operational problems usually consists of monitors at the peak of
the roof. A monitor runs the length of building to permit con-
vective removal of the emissions, which rise slowly. As an
alternative, smaller fan-powered monitors are sometimes in-
stalled above each emission source.
As the emissions drift upward, they may impair the visual
or respiratory functions of the EOT crane operator; for this
reason he may wear respiratory equipment or the EOT crane cab
may be air conditioned. The heavier particles usually settle
out on process equipment such as the primary uptake hood and EOT
crane, and on structures such as runways and roof trusses.
Fugitive emissions may cause buildup of haze in the upper
portion of naturally ventilated buildings. Even if powered
monitors are used, pockets of dead air and haze may form at
certain locations.
These monitors could be tied into a collection system by
enclosing the sides of the roof monitors and ducting to induced-
draft fans and baghouses. The powered monitor units could also
be enclosed and ducted similarly.
BUILDING ENCLOSURE
Because of the problems with the currently used hooding
systems, which are ineffective when the converter is pouring or
receiving charge, the concept of total building enclosure has
arisen. One smelter is experimenting with total enclosure of
the converter building, discharging the fugitive emissions by
means of a powered roof monitor system. This approach, however,
entails some problems. Currently, only three of the five sec-
tioned roof monitors at this smelter are powered; the other two
sections are gravity-type monitors. Also, when building access
doors are left in the open position, the design concept of total
building enclosure is not realized. With proper design, main-
tenance, and cooperation of plant personnel, collection of
converter fugitive emissions by total building enclosure could
be very effective. Proper design would involve such factors as
tightness of the building, capacity of the takeaway fans,
movable truck and rail doors, lighting, and ventilation through-
out the entire building to ensure worker safety. Maintenance,
63
-------
particularly of the air moving equipment, would be important to
minimize problems with system ventilation imbalances. Training
and daily performance of employees would be very important to
ensure that doorways, louvers, or other openings are kept closed
at all times when not in use. Such careful practice by plant
personnel would minimize disturbance of airflows.
The merit of total converter building enclosure is the
possibility that such a system could capture nearly all of the
fugitive emissions. The scheme entails several problems, how-
ever. Design of a total evacuation system that could provide
the proper air changes in all working areas would be difficult.
Even with an all-powered roof monitor system to pull the air
through the building, pockets of dead air are likely, especially
in corners and around objects that obstruct the airflow. With a
totally enclosed building, air movement must be properly dis-
tributed, even in the difficult areas such as around the con-
verters, crane runways-, EOT crane repair areas, and converter
aisles. Building access doors and mandoors must be opened at
times to permit movement of. materials and personnel. Proper
ventilation of a totally enclosed building may require the use
of air ducts to convey air to specific locations. Such a system
would be "short-circuited" by passage of air through opened
doorways, and disruption of the airflow patterns would reduce
the effectiveness of the ventilation system in removing fugi-
tives and changing the building air.
Other problems with total building enclosure are difficulty
of retrofit and high cost. Building structure and support may
have to be reinforced to handle the stress of added side and end
walls and a roof monitor system. Capital cost of totally
enclosing an existing converter building could be very high.
AIR CURTAINS
Mitsubishi Metal Corporation at Onahama, Japan, controls
some of the fugitive emissions from a Peirce-Smith converter by
the use of secondary hooding and an air curtain. (Details are
given in Appendix B. ) This technique could be modified for
application to multihearth roasters, reverberatory furnaces, and
other smelter process equipment.
Fugitive emissions at the Onahama smelter are controlled by
a combination of secondary hooding, air curtains, and building
enclosure and evacuation. Visual observation indicates that the
system is 80 to 90 percent effective. With additional building
evacuation, a 90 percent capture level could be maintained. The
present system does not impede converter operations. Although
visibility from the EOT crane cab is not seriously impaired by
64
-------
gases and particulate, additional building ventilation could
improve visibility and reduce potential exposure in the EOT
crane cab.
A proposed secondary hood system incorporating the air
curtain technique (Figure 36) would consist of steel side panels
with a back and top panel, forming a partial enclosure. The
front, or side at which the crane with ladle approaches the
converter, is open. The top panel would have an opening suf-
ficient to permit cables from the EOT crane to pass into the en-
closure without damaging the structure or crane cables when
charging matte, removing ladles of slag or blister copper, or
performing other operations.
Air is blown from one side of the top panel opening and
collected on the other side of the opening. The air flow rate
across the opening is 1000 Nm3/min. The air entrains the rising
fugitive emissions, then is discharged to a collection system.
65
-------
MAIN HOOD
AIR CURTAIN
SIDE VIEW
-------
SECTION 7
PROPOSED ALTERNATIVE CONTROLS AND PROCESS CHANGES
This section describes some of the alternative process
technologies that could reduce the fugitive emissions from
copper smelting operations. One alternative system involves the
use of a cascading arrangement, in which matte from a smelting
furnace (Noranda, Outpkumpu, electric arc) is discharged by
gravity via launders with hoods to a holding furnace, and then
by gravity via launders or runners to a Hoboken converter with a
swing-away secondary hood (for use during slagging or blister
copper pouring). Another alternative is use of a furnace
similar to a Q-BOP furnace in the steel industry. Emissions
from ladles could be controlled by use of an EOT crane evacua-
tion system or by use of bottom-pour ladles with covers. These
and other possible means of fugitive emissions control are de-
scribed below.
CASCADING SYSTEM, STAGGERED SYSTEM, AND INDUCTION PUMPING
A cascading system, unlike other systems discussed in this
section, would require a change in the traditional smelter
layout but should nearly eliminate all sources of fugitive
emissions. In a cascade smelter design the roasters (if used),
smelting furnaces, converters, and anode or refining furnaces
would be arranged to receive products or slags by way of covered
launders, runners, refractory-lined pipes, or similar equipment,
without the use of ladles (Figure 37). Green feed would be
transported to the roasters, and calcined feed would be screw-
conveyed or possibly conveyed pneumatically to a storage bin and
then to a smelting furnace. Matte could flow by gravity from
the smelting furnace to a holding furnace and then to an anode
furnace. The furnaces would be arranged in a stepped manner.
Slags from the smelting furnaces could be tapped and disposed of
as is currently done.
A cascading system would require the lifting of raw mate-
rials a considerable height and would require a building some-
what higher and wider in some areas than those in current use.
It also would require additional energy to transport the mate-
rials initially to a higher level. Operational procedures would
be changed in that less movement of the EOT cranes would be
required. The use of intermediate holding vessels would be
67
-------
Ol
CO
SUPPLE-
MENTAL
FUEL AND
BURNER
STORAGE
BIN
FROM
ROASTER
\ \
N. X
v
EMERGENCV !
ALTERNATE
LAUNDER.
SCHEMATIC
CASCADING
ANODE WHEELS SYSTEM
Figure 37. Cascading gravity flow.
-------
expanded, and furnaces would be aligned in a fanning layout
rather than in rows. Transportation from unit to unit would be
by launders, except for charging to the first unit in the
process. Maintenance and operations could be somewhat restric-
ted by the proximity of the various process flows. Overall,
control of emissions would be facilitated by the holding fur-
naces and elimination of the EOT crane for transport, which
would eliminate process holdups. A pendant floor-controlled EOT
crane would be installed over each process furnace for use in
emergencies and for cleanup, repairs, and maintenance. Such a
system using evacuated canopied hoods (Figure 38) would minimize
fugitive emissions.
In operation of a new smelter designed with the cascading
arrangement, problems would arise because of the new operating
techniques. Moreover, one could expect buildup of accretions in
the transfer launders, and similar operating problems. Such
difficulties are common in operation of systems based on new
technology; with a problem-solving approach, the system
designers and operators could determine and implement the needed
modifications.
As an alternative to the cascade design, a horizontal
layout could be designed for use with induction pumping to move
hot fluids vertically or horizontally without the use of ladles
and without open exposure of the fluids. The induction pumping
would require large expenditures of power to move the materials
from one point to another, but control of gases and fugitive
emissions could be achieved with the relatively simple control
equipment. The envisioned fugitive emission control system
would consist of hooding at the transfer points with the neces-
sary ducting, fans, and baghouse (Figure 39).
Operation of the induction pumping system would require a
building similar in height to the current structures but slight-
ly wider. The basic process furnaces would be at ground level,
as at present. Again the furnaces would be arrayed in a stag-
gered pattern rather than in a line. The operator would control
the flow to and from adjacent holding vessels; EOT cranes would
not be needed for handling of ladles, as with the cascade sys-
tem, an EOT pendant floor-controlled crane over each furnace
would be used for cleanup, repairs, and maintenance. Control of
the process and of emissions would be facilitated, but power
consumption, equipment costs, and maintenance requirements would
be greater.
OXYGEN ENRICHMENT
When a Peirce-Smith converter is blown with air, the oxygen
in the air reacts with sulfur in the matte to form S02 and
liberate heat. Besides removing the undesirable sulfur as S02,
69
-------
MENTAL X-'TWAS™
FUEL AND ~r<^
BURNER f- •*
STORAGE BIN
FROM ROASTER
FEED
BIN
CONVEYOR
SLAG
LADLE
SCHEMATIC
CASCADING
SYSTEM
Figure 38.
ANODE WHEELS
Fugitive emission collection system for cascading gravity flow.
-------
STACK
STORAGE
BIN V | xi
FROM ^JC-'
ROASTER
HYDROGEN
CONVERTERS
/ELECTRIC
ARC
FURNACE
(EAF)
/XFEED PORT
BIN
CONVERTER
Figure 39. Fugitive emission collection system for cascading/induction/gravity flow.
-------
oxygen also reacts with iron in the presence of silica to form
the slag. Large amounts-of air must be blown into the converter
to provide enough oxygen for these reactions. The blowing rate
also must be high enough to produce the blister copper in a
designated time cycle. Release of fugitive emissions through
clearances, such as that between the primary hood and converter,
depends partially on blowing rate, the emissions increasing with
increasing rate of blowing.
With oxygen enrichment, the blowing rate to a Peirce-Smith
converter could be reduced, with resultant reduction of fugitive
emissions. Enrichment of blowing air with 5 percent oxygen
would theoretically allow reduction of a 68,000 m3/h blowing
rate by about 2700 m3/h. In addition to reduction of fugitive
emissions, the reduced blowing rate of air with higher concen-
trations of oxygen also increases the S02 concentration in the
gas stream to an acid plant.
Q-BOP FURNACE
The Q-BOP (Figure 40) furnace used in the steel industry
could be applied as a converter furnace at a copper plant, with
oxygen or Q2-enriched air as the blowing medium use. Use of the
Q-BOP furnace in the steel industry has both increased produc-
tion and reduced production costs. In addition to these advan-
tages, the Q-BOP can be operated in an enclosure or "doghouse"
to prevent escape of fugitive emissions. Such a furnace with
fugitive emissions control system is installed and operating at
the South Chicago District of Republic Steel Corporation. A
schematic of that furnace and its gas cleaning system is shown
in Figure 40. Where open hearth (reverberatery type) furnaces
were used without oxygen enrichment, the production rate was 23
Mg of steel per hour; with oxygen enrichment production rose to
40 Mg per hour. With the Q-BOP furnace, production has in-
creased to 163 Mg per hour.
Secondary emissions still must be controlled around the
other process furnaces. Use of this system at copper smelters
might permit the use of fewer converters and could yield a
stronger S02 stream, but would require holding furnaces for good
process control. Because refractory lining would be required,
two units would be needed to maintain continuous operation.
Maintenance requirements would be somewhat greater with the
refractory-lined unit, in which temperatures may be slightly
higher. The building structure could be smaller than those in
current use.
72
-------
FURNACE
ENCLOSURE
SECONDARY
HOOD
ALVE
7 '
\
\
^SCRUBBER
STACK
INLET
DAMPER
QUENCHER
GAS CLEANING SYSTEM
I.D. FAN
Figure 40. Q-BOP furnace enclosed in a "doghouse" to prevent
fugitive emissions (from Iron and Steel Engineer, November 1978)
73
-------
CRANE EVACUATION OF LADLE EMISSIONS
The EOT could be modified to minimize fugitive emissions
from ladles during transport, filling, and pouring by use of a
capture hood fixed to the spreader beam (Figure 41). The cap-
ture hood would also be fixed to a sectionalized telescopic
column, similar to that used in the steel industry's stiff leg
EOT crane for moving ingots to and from a soaking pit.
An exhaust fan would be mounted on the trolley and con-
nected with ducting to the telescopic column duct. The EOT
crane would position itself over the ladle or slag pot and as
the molten materials are discharged into the receptacle, the
evacuation blower on the trolley would draw the emissions to the
trolley deck. This stream could be discharged to the overhead
building monitor or ducted to the crane walkway and then to the
building column line for discharge to a collector system. The
evacuation system would operate during transportation and pour-
ing of the ladles. Maintenance requirements could be high if
the telescopic unit were damaged by poor crane operations.
FLOOR-OPERATED CHARGING
A floor-operated charging machine, illustrated in Figure
42, could replace the EOT cranes that transport ladles of matte
or slag. A charging machine could lift a ladle of matte, move
back and pivot 180 degrees, then move the ladle of matte to the
converter. The arms would life the ladle to the desired height
and tilt it for discharge of the matte into the converter. The
converter would be contained or totally encapsulated within a
hood to capture the fugitive emissions. A portion of the hood
for the converter would be retractable for maintenance when the
EOT crane must be used. Use of the floor-operated charging
machine would be limited to new installations and the converter
aisle would be wider than those in the present converter build-
ings.
Emissions escaping the primary hood would be ducted from
the top of the encapsulated structure. This floor-charging
technique would minimize fugitive emissions in the converter
aisle during charging.
TOP-COVERED BOTTOM-POUR LADLES
Whether EOT cranes or charging machines are used, the
transport of molten materials by means of open ladles generates
visible fugitive emissions. These ladle emissions could be
reduced by use of fitted covers that could be placed on or re-
moved from the ladle with minimal effort (installation of such
covers could pose some problems at some existing plants.)
74
-------
FAR SIDE - ID FAN
AUX HOIST DRUM
TRANSFER
DUCT
TELESCOPIC CAPTURE
DUCT (SIMILAR TO
STEEL MILL SOAKING
PIT CRANE)
-J
m
SPLIT RUBB
COVER OVER
NSFER DUCT
TRANSFER DUCT
TO FAN
AND BAGHOUSE
(CAN BE MOUNTED
OVERHEAD UNDER
THE ROOF TRUSSES)
BLDG
COLUMN
HOIST
DRUM
'CAPTURE HOOD
FIXED TO
SPREADER BEAM
LADLE
TRANSFER
DUCT
E.O.T.
GIRDER
TELESCOPIC
CAPTURE
DUCT
Figure 41. EOT crane with telescopic stiff leg.
-------
Figure 42. Modified charging machine.
-------
In conjunction with covers, a specially designed bottom-
pour ladle with stopper rods (similar to that in Figure 43)
might be used at some smelters for transport of molten metal.
Such a ladle, with an autopour unit attached to the EOT crane
(Figure 43), is used in the steel industry, and the autopour
unit controls the operation of the stopper rod mechanism when
the steel is transferred into a mold or tundish, etc. At a
copper smelter the EOT crane operator could control the flow of
matte directly into a converter furnace or the flow of blister
copper into an anode furnace. With a cover over the ladle or
the use of an overhead crane equipped with an evacuation system,
fugitive emissions would be greatly reduced. A bottom-pour
ladle could be seated on a ladle support, and the ladle tapped
into a specifically designed opening in the end of a converter
through a refractory-lined airtight joint/cover. In such a
system, the mouth of the converter could be made smaller; it
would be used solely for pouring and not for receiving.
INDIVIDUAL FURNACE ENCLOSURES
In another fugitive emission control scheme, each furnace
(e.g. a Peirce-Smith converter) would be operated in its own
enclosure (Figure 44), with separate exhaust systems that could
tie into a central point. For each furnace an EOT crane would
be remotely controlled by an operator outside of the enclosure;
during maintenance the operator would enter the enclosure at the
platform levels and would use the captive EOT crane for main-
tenance around the furnace. Matte, slag, and blister copper
ladles would be transferred to and from the enclosure via a
four-wheel rail-mounted car, also remotely-controlled, that
would pass through a sliding door.
Individual furnace enclosures would require the use of
closed-circuit television. Gas evacuation systems would be
provided to handle the fugitive emissions from each furnace.
Such individual furnace enclosures offer a major advantage over
total building enclosure in that emissions do not spread
throughout the building and can be better controlled. Also,
with separate furnace enclosures all of the building air is not
evacuated, but only that needed to remove fugitive emissions to
provide the required air changes in the smaller enclosure.
Maintenance requirements would be greater than in current
systems, and failure of a captive EOT crane would require rapid
remedial maintenance. Another problem would be supplying proper
ventilation within the area during maintenance if the unit is on
stream. It is envisioned, however, that the operator would
usually work outside of the enclosure and would observe the area
by means of closed-circuit television. Emissions would be
minimal.
77
-------
Figure 43. Hydraulic cylinder mounted on barrel of ladle rigging
raises and lowers stopper rod to control flow of molten steel
from ladle to ingot mold. (Courtesy, Blaw Knox Equipment, Inc.)
From The Making, Shaping, and Treating of Steel by United
States Steel. Copyright (c) 1971, United States Steel Corporation.
Used with permission of United States Steel Corporation.
78
-------
ENCLOSURE
FUGITIVE
EXHAUST
DUCT
REMOTE AND
PENDANT
OPERATED
CAPTIVE
CRANE
ENCLOSURE
POSITION
CHARGING
MATTE,
ETC.
ENCLOSURE
JIB BOOM TO
REMOVE LADLE COVER
REMOTELY CONTROLLED
CONVERTER
IN POSITION\
FOR
CHARGING
LADLE
COVER
TUYERE PUNCHER
MANUAL OR
REMOTELY CONTROLLED
SLAG OR
BLISTER
COPPER LAOLE
POSITION
STEEL CURTAIN
DIVIDER
CABLE PULLER OR
CABLE REEL MOTORIZED
TRANSFER CAR
ENCLOSURE
Figure 44. Individual furnace enclosure.
-------
SECTION 8
REFERENCES
1. Anonymous. Surface Mining and Our Environment. U.S.
Department of the Interior. U.S. Government Printing
Office, Washington, D.C., 1967.
2. Hayashi, M., H. Dolezal, and J.H. Bilbrey, Jr. Cost of
Producing Copper from Chalcopyrite Concentrate as Related
to S02 Emission Abatement. U.S. Bureau of Mines, RI 7957,
1974.
3. Coleman, R.T. Population Control and Heat Recovery from
Non-Ferrous Smelters. Vol. II. Radian Corporation.
Austin, Texas, 1977.
4. Bailey, J.B., et al. Oxygen Smelting in the Noranda
Process. Presented at the 104th AIME Annual Meeting, New
York, February 1975.
5. Harkki, S.U., and J.T. Juusela. New Developments in
Outokumpu Flash Smelting Methods. Presented at Annual
Meeting, AIME, Dallas, February 1974.
6. Background Information for New Source Performance Stan-
dards: Primary Copper, Zinc, and Lead Smelters. U.S.
Environmental Protection Agency, EPA-450/2-74-002a,
Research Triangle Park, N.C., October 1974.
80
-------
APPENDIX A
COST ANALYSIS
Detailed cost estimates are given for secondary hooding and
air curtain controls. Brief summaries are given also for rela-
tive costs of other alternative control systems and estimated
energy requirements. The measurements cited are in English
units, as in the original cost studies.
COSTS OF SECONDARY HOODING SYSTEMS FOR CONVERTERS
This section is a capsule discussion of costs of the fol-
lowing major types of secondary hoods:
0 Fixed type: made of structural steel with an ellipti-
cal cross-section. It is attached to the primary or
uptake hood.
0 Fixed and movable: consists of a movable intermediate
hood and a hood fastened to the gate. Both hoods are
made of structural steel with elliptical cross-
sections so that they telescope in the retracted mode.
0 Swing-away type with fixed overhead hood: made of
structural steel, refractory lined, and supported by
pivot arms with a motorized drive to permit position-
ing during blowing and pouring operations.
0 Combination of fixed and movable swing-away type.
Cost Parameters
This section describes the various items that must be in-
stalled or modified to achieve control of fugitive emissions
from the Peirce-Smith converter, source of a great quantity of
secondary emissions. It does not include costs of certain oper-
ating procedures that would minimize fugitive emissions, e.g.,
maintaining minimal clearance between the primary uptake hood
and the apron of the converter, or maintaining proper matte
charges to provide for direct flow of gases from the mouth of
the converter to the centerline of the primary uptake hood.
81
-------
Following are descriptions of the items evaluated.
0 The fixed hood has an elliptical cross-section of 17
feet 6 inches on the major axis and 7 feet on the
minor axis; it is 9 feet 6 inches long. The plate is
3/8-inch carbon steel, with stiffeners of 7-inch
channels. The fixed hood is bolted to the primary
hood and to the smoke plenum of the secondary duct
system.
0 The movable hood in the retracted position is parked
above the fixed hood. It has an independent track
system with a five-speed, double-grooved hoist unit
and slack cable limit switch. The movable head is 9
feet long and is elliptical, with a major axis of 18
feet 6 inches and minor axis of 7 feet 6 inches.
These dimensions provide a 3-1/3-inch clearance be-
tween the movable and fixed hoods. There are mating
plates on the lower end of the fixed hoods and on the
top of the movable hood. The lower end of the movable
hood is fitted with a 12-inch thick asbestos-type
curtain that follows the elliptical perimeter to form
a seal with the gate hood. The movable hood is con-
structed of 3/8-inch carbon steel with stiffeners of
7-inch channels.
° The gate hood is elliptical in cross-section with a
major axis of 16 feet 6 inches and a minor axis of 6
feet 6 inches; it is 9 feet long. Clearance between
the fixed hood and the gate is thus 3-1/2 inches. The
hood would be bolted to the gate. The place is
3/8-inch carbon steel reinforced with 7-inch channels.
The dimensions listed above would be modified for each
converter layout to provide the required clearances. Design
considerations may dictate that the fixed hood is the largest
unit, with the movable hood under it and the gate hood under the
movable hood.
0 If height of the crane runway rail presents a problem,
the smoke plenum of the secondary hooding duct system
could be fitted as follows: The plenum would span the
primary uptake hood and would have a secondary hood
dust bin affixed on each end. The dust bins would be
equipped with pneumatic dust valves and discharge
pipes. This evaluation includes no provision for
removal of dust in the dust bins. The smoke plenum
for this study is 4 feet by 4 feet 8 inches by 21
feet. It is constructed of 3/8-inch steel with 6-inch
channel stiffeners.
82
-------
0 The secondary hooding duct system would have an uptake
from each dust bin adjacent to the converter and then
pass to its main ducting header for fugitive emis-
sions. The damper valve shown would be adjacent to
the main ducting header and would be closed when the
converter is out of service. Existing facilities
would determine the path of retrofit. The gases go to
a dust bin ahead of the fans and from there to the
breeching into the main converter gas duct and to the
stack. For this study, the main duct runs are 600
feet long.
0 The fans considered in this estimate are Buffalo Forge
Type 1320 BL, single inlet, Arrangement 1, Class 3,
with 145 bhp, 785 rpm, 80,000 ft3/min at 200°F. There
would be one fan for each converter in the plant; as
many fans as are required would be tied into the sys-
tem.
0 Support items for this system include piping, wiring,
foundations, supports for ducting every 20 feet,
expansion joints, miscellaneous platforms, and walk-
ways. Valves, fans, dust bins, and similar items are
flanged for ease of maintenance.
The retrofit factor was considered as being midway between
a new installation and an existing "difficult" installation.
Estimates of total installed costs are based on current
(1978) costs for major components of specified sizes, as pro-
vided by equipment suppliers. Estimates of fabrication costs
and installation in the southwest are based on general accepted
engineering practice (e.g., as given in Richardson's, Mean's,
the Chemical Engineering Index, and K. M. Guthrie) and on data
from PEDCo engineering files.
A 5.0 percent contingency factor is applied to the total of
the direct and indirect costs to allow for changes in equipment
or design changes. An escalation factor of 7-1/2 percent per
year is used to account for increases in cost of equipment,
labor, and services before and during construction. Direct
capital costs include equipment, instrumentation, piping, elec-
trical, structural, foundations, site work, insulation, and
painting. Indirect capital costs include engineering costs,
contractor's fee and expenses, interest (accrued during con-
struction on borrowed capital-estimated at 9 percent per year),
freight, offsite expenditures, taxes (sales tax of 4 percent of
equipment cost), startup or shakedown, and spares.
Annualized costs include both operating costs and fixed
capital charges: utilities, labor and fringe benefits, mainte-
nance, plant overhead and total fixed costs, which amount to
83
-------
19.97 percent of total installed costs and consist of deprecia-
tion over 15 years at 6.,67 percent unless otherwise indicated,
property insurance at 0.3 percent, property taxes at 4 percent,
and interest on borrowed capital at 9 percent.
Capital Costs
Table A-l shows the direct costs, indirect costs including
one year of contingency and escalation, and total capital costs
for plants containing one to nine converters without a baghouse
in the fugitive emission discharge system. Table A-2 includes
the system of Table A-l with addition of a baghouse and appro-
priate increase in the fan pressure design.
Operating Costs
Operating costs include operating labor at $8 per man-hour,
supervision at 15 percent of labor, maintenance for labor and
supplies at 2 percent of total capital costs, maintenance mate-
rials at 15 percent of maintenance labor and supplies, electric-
ity at 35 mills per kWh, plant overhead at 50 percent of opera-
tions, and payroll at 20 percent of the operating labor costs.
The fixed costs include a straight-line depreciation over 15
years, 0.3 percent for insurance, 4 percent for taxes, and 9
percent for capital costs. Table A-3 lists the operating costs
for a multiconverter plant without a baghouse in the fugitive
emission discharge system. Table A-4 includes the system of
Table A-3 with addition of a baghouse and appropriate increases
in energy and maintenance costs.
Additional handling of slag and blister ladles may cause
delays in operation of the movable and swing-away converter
hoods. It is estimated that a delay of 5 to 15 seconds may
occur with each ladle movement, equivalent to a total delay of 3
to 10 minutes per day or a 0.23 to 0.7 percent slowdown in
production. This loss is calculated on an annual basis as part
of the operating cost since it is negligible in comparison with
other delays that are encountered (e.g., delay because matte is
unavailable, because the anode furnace cannot accept more
blister copper, or because of maintenance of converters or
furnaces.
Each of these systems is connected to a main discharge duct
and an exhaust fan that exhausts to an existing stack.
COSTS OF AIR CURTAIN CONTROLS
Order-of-magnitude costs (± 35 percent) of an air curtain
for control of fugitive emissions were developed in a manner
somewhat similar to that for secondary hooding systems.
84
-------
TABLE A-l. ESTIMATED CAPITAL COSTS OF SECONDARY HOODING AT
MULTICONVERTER PLANT WITHOUT BAGHOUSE
(dollars)
No. of
converters
1
2
3
4
5
6
7
8
9
Direct
costs
760,000
1,216,000
1,532,000
1,771,000
2,211,000
3,219,000
3,601,000
3,880,000
4,402,000
Indirect
costs
532,000
785,000
963,000
1,255,000
1,463,000
2,122,000
2,383,000
2,545,000
2,850,000
Total
costs
1,292,000
2,001,000
2,495,000
3,026,000
3,674,000
5,341,000
5,984,000
6,425,000
7,252,000
85
-------
TABLE A-2. ESTIMATED CAPITAL COSTS OF SECONDARY
HOODING AT MULTICONVERTER PLANT WITH BAGHOUSE
(dollars)
No. of
converters
1
2
3
4
5
6
7
8
9
Direct
costs
1,122,000
1,616,000
2,127,000
2,587,000
3,103,000
4,850,000
5,523,000
6,093,000
6,877,000
Indirect
costs
736,000
1,007,000
1,298,000
1,714,000
1,966,000
2,936,000
3,466,000
3,792,000
4,244,000
Total
costs
1,858,000
2,623,000
3,425,000
4,301,000
5,069,000
7,786,000
8,989,000
9,885,000
11,121,000
86
-------
TABLE A-3. ESTIMATED ANNUAL OPERATING COSTS OF SECONDARY HOODING
AT A MULTICONVERTER PLANT WITHOUT BAGHOUSE
(dollars)
No. of
converters
1
2
3
4
5
6
7
8
9
Labor and
supervision
10,000
21,000
31,000
41,000
51,000
62,000
72,000
82,000
93,000
Maintenance ,
labor, supplies,
and materials
30,000
46,000
57,000
70,000
85,000
124,000
138,000
148,000
167,000
Overhead
plant and
payroll
22,000
38,000
50,000
64,000
78,000
105,000
119,000
131,000
149,000
Utilities
1,000
3,000
4,000
5,000
6,000
8,000
9,000
10,000
11,000
Fixed
costs
258,000
400,000
498,000
604,000
734,000
1,077,000
1,195,000
1,283,000
1,448,000
Total
annual
costs
321,000
508,000
640,000
784,000
954,000
1,376,000
1,533,000
1,654,000
1,868,000
00
-------
TABLE A-4. ESTIMATED ANNUAL OPERATING COSTS OF SECONDARY HOODING AT
A MULTICONVERTER PLANT WITH BAGHOUSE
(dollars)
No. of
converters
1
2
3
4
5
6
7
8
9
Labor and
supervision
17,000
28,000
3:8,000
48,000
58,000
72,000
82,000
92,000
103,000
Maintenance,
labor, supplies,
and materials
43,000
60,000
79,000
99,000
117,000
179,000
207,000
227,000
256,000
Overhead
plant and
payroll
33,000
50,000
66,000
83,000
99,000
140,000
161,000
178,000
252,000
Utilities
80,000
122,000
226, QOO
343,000
404,000
523,000
878,000
1,039,000
1,209,000
Fixed
costs
371,000
524,000
684,000
859,000
1,012,000
1,555,000
1,795,000
1,974,000
2,221,000
Total
annual
costs
544,000
784,000
1,093,000
1,432,000
1,690,000
2,469,000
3,123,000
3,510,000
4,041,000
CO
00
-------
The design evaluated here differs from the Mitsubishi air
curtain system in that the side panels are extended to contain
the area of the ladle awaiting blister copper or slag from the
converter. Also, partial covering is placed on the approach
side (Figure 37).
The air flow across the top is set at 1000 Nm3/min, but the
collection side is designed with its own suction fan to handle
up to 2500 Nm3/min so as to create a flow pattern that will
capture the fugitives during charging, teeming, slagging, and
similar operations.
Tables A-5 and A-6 show the total installed capital and
annual operating costs.
RELATIVE COSTS AND ENERGY REQUIREMENTS
Table A-7 summarizes the costs of alternative control
systems relative to the systems now in widespread use. Table
A-8 lists the estimated energy requirements.
89
-------
TABLE A-5. ESTIMATED CAPITAL INSTALLED COSTS OF
AIR CURTAIN TYPE HOODING WITH BAGHOUSES AT MULTICONVERTER PLANT
(dollars)
No. of
converters
I
2
3
4
5
6
7
8
9
Direct
costs
$ 372,200
736,900
987,800
1,365,500
1,621,200
2,111,300
2,688,700
3,242,000
3,591,200
Indirect
costs
$ 586,700
926,700
1,222,200
1,708,800
2,010,200
2,725,500
3,406,300
4,189,800
4,630,300
Total
costs
$1,082,000
1,878,000
2,495,000
3,470,000
4,099,000
5,460,000
6,880,000
8,389,000
9,280,000
Includes 5% contingency and 7-1/2% escalation for 1 year.
90
-------
TABLE A-6. ESTIMATED ANNUAL OPERATING COSTS OF AIR CURTAIN TYPE HOODING
WITH BAGHOUSES AT MULTICONVERTER PLANT
(dollars)
No. of
converters
1
2
3
4
5
6
7
8
9
Labor and
supervision
17,000
28,000
38,000
48,000
58,000
72,000
82,000
92,000
103,000
Maintenance,
labor, supplies,
and materials
25,000
43,000
57,000
80,000
94,000
126,000
158,000
193,000
213,000
Overhead
plant and
payrol 1
20,000
29,000
36,000
47,000
54,000
76,000
92,000
110,000
120,000
Utilities
59,000
67,000
80,000
145,000
168,000
225,000
240,000
297,000
349,000
Fixed
costs
220,000
382,000
506,000
704,000
832,000
1,109,000
1,398,000
1,704,000
1,886,000
Total
annual
costs
341,000
549,000
717,000
1,024,000
1,206,000
1,608,000
1,970,000
2,396,000
2,671,000
-------
TABLE A-7. RELATIVE COST EVALUATION OF ALTERNATIVE AND EXISTING SYSTEMS
Alternative
system
Cascade
Staggered with
Induction
pumping
4-BOF
Crane
evacuation
Covered bottom-
pour laoles
Floor operated
charger
Flash smelter
tpboken
converter
Individual
furnace
enclosure
Building
evacuation
Compared with
Roaster
Xc
X
X
X
Dryer
X
X
X
X
teverb
X
X
X
X
X
X
X
X
X
EAFa
X
X
X
X
X
X
X
X
Flash
shelters
X
X
X
X
X
X
X
X
P-S
converter
X
X
X
X
X
X
X
X
X
Anode
Furnace
X
X
X
X
X
X
X
BIDS costs b
•ligher
X
X
X
X
X
X
Same
X
Less
X
Problem
areas
Maintenance
Equipment location
Proximity of furnaces
Operating techniques
Maintenance
Equipment location
Proximity of furnaces
Operating techniques
Maintenance
Enclosure design
Operating techniques
Maintenance
Maintenance
Maintenance
Operating techniques
Mai ntenance/operati ng
techniques
Mai ntenance/operati ng
techniques
Air movement or
changes
Maintenance
Air movement or
changes
Capital
installed costs "
Higher
X
X
X
X
X
X
X
Same
Less
X
X
Annual i zed .
operating costs
Higher
X
X
X
X
X
X
X
Same
X
X
Less
r • b
Emissions
Minimal
X
X
X
X
Less
X
X
X
X
X
Same
INJ
Electric arc furnace.
X indicates relative cost of alternative system; annualized operating costs include fixed operating and maintenance.
c X indicates conventional equipment with which alternative is compared.
-------
TABLE A-8. ESTIMATED ENERGY REQUIREMENTS FOR CONTROL OF FUGITIVE
(GASEOUS AND PARTICULATE) EMISSIONS AT INTAKES AND DISCHARGE POINTS
Process equipment
Roaster
Dryer
Outokumpu furnace
Noranda furnace
Electric arc furnace
Reverberatory furnace
Peirce-Smith converter
Hoboken converter
Anode furnace
EOT crane
Energy requirement, kWh/h
Secondary hoods;
capture hoods
minimum /maximum
192/200
156/162
30/149
60/149
89/176
53/149
168/216
17/108
55/108
7/73
Individual,
enclosure '
27
38
90
50
110
90
11
17
11
Building .
evacuation '
271
38
411
172
444
355
365
305
365
vo
U)
Energy expended per unit; gas stream discharged after passing through a baghouse.
Operating only when emissions are being captured.
Operating continuously.
Air changes estimated at 12 per hour.
-------
APPENDIX B
TRIP REPORT: MITSUBISHI METAL CORPORATION,
. ONAHAMA, JAPAN
27 July 1979
TRIP REPORT
DCN 79-201-010-05-X
To: Alfred B. Craig, Jr.
Project Officer, lERL-Ci
From: Richard T. Coleman, Jr.
Project Director, Radian Corporation
Subject: Site visit to the Mitsubishi Metal Corporation
primary copper smelter in Onahama, Japan
Trip date: 9 and 10 July, 1979
Contacts: Izumi Sukekawa, Group Manager, Technical Sales Dept.
Shun-Ichi Ajima, Manager, Technical Sales Dept.
Hiroshi Kono, Manager of Operations, Onahama Smelting
& Refining, Ltd.
Yoshiyuku Tsuji, Metallurgist, Asst. Superintendent
of R&D, Onahama S&R
Purpose: Investigate copper converter fugitive emission
controls
Summary:
The combination of secondary hooding, air curtains, and
building enclosure and evacuation used to control fugitive emis-
sions at the Onahama smelter is approximately 80 to 90 percent
effective based on visual observation. Additional building
evacuation would certainly enable a 90 percent capture level to
be maintained. The present system does not impede converter
operations. Visibility from the crane cab is not seriously
impaired by gases and particulate. However, additional building
ventilation could improve visibility and reduce potential ex-
posure in the crane cab.
94
-------
Mitsubishi personnel did not seem to favor any detailed
study of their facility by EPA. Any study of a system similar
to Mitsubishi's would have to be a demonstration conducted at a
U.S. primary copper smelter. It is recommended that this system
be investigated in detail by both EPA and NIOSH as a potential
solution to the fugitive emissions problem and as an engineering
control for S02, particulate, and volatile metals (Pb, As, etc.)
in primary copper smelters.
General:
The initial meeting with Messrs. Sukekawa and Ajima on July
9 took place in Mitsubishi Metal's Tokyo office. We discussed
the purpose of our trip, emphasizing our interest in fugitive
emission controls. We explained lERL-Ci's involvement in non-
ferrous metals research during the past four years and indicated
that demonstration of effective controls is a key R&D need.
Their reaction during that meeting and the subsequent trip
to Onahama on July 10 was that they have demonstrated that their
control technology works effectively and it is commercially
available. They did not indicate any willingness or interest in
participating in an EPA-funded testing or demonstration project.
Messrs. Sukekawa and Ajima were very cooperative and they
and Messrs. Kono and Tsuji at the Onahama smelter provided a lot
of information concerning both the converter controls and the MI
(Mitsubishi) smelting process. This information is discussed
below.
Converter Fugitive Emission Controls:
Emissions from the five converters in the Onahama smelter
are controlled in four ways. These are:
0 Primary hoods,
0 Secondary hoods,
0 Air curtains, and
0 Converter aisle building exhaust ventilation.
This combination of controls was observed to work effec-
tively and captured an estimated 80 to 90 percent of the fugi-
tive gases leaving the converter. Only the building exhaust
ventilation appeared to be slightly underdesigned. An increase
in the gas volume evacuated from the building would probably
assure a 90 percent control efficiency.
95
-------
The converter control system is pictured schematically in
Figure B-l. During normal blowing and standby, approximately
950 Nm3/min of process gas are drawn through each primary hood.
The primary hoods are not water cooled but still fit tightly on
each converter without severe buckling. A gap of only two to
three inches is maintained between the primary hood and the
converter furnace. This enabled almost complete capture of SO2
to be maintained during the blowing cycle. Fugitive emissions
during blowing were observed to be minimal.
During charging and pouring, the primary hood draft is
reduced by approximately 65 to 80 percent. The gas concentra-
tion being fed to the acid plant is used as a control on the
primary hood damper. The draft on the primary hood is suf-
ficient to allow perhaps 30 to 50 percent control of fugitive
emissions during the period when the converter was rolled out.
This is possible only because no air is introduced into the
tuyeres during these periods. Control of the remainder of the
fugitives during charging and pouring is provided by the
secondary hoods, air curtains, and building exhaust ventilation.
The secondary hoods are sheet metal panels on either side
of the converter which rise approximately 14 meters (50 feet)
from the floor of the converter aisle. At the top of these
panels, three fans are fitted into the hood. The fans create an
air curtain across the slot in the top of the secondary hood.
The slot is large enough to allow the crane cables to be
maneuvered during both charging and pouring. On the other side
of the slot is a duct which collects the exhaust from the three
air curtain fans. The exhaust duct for the secondary hood is at
the top of the sheet metal panels on the side farthest from the
converter aisle. This arrangement is depicted in Figure B-2.
The secondary hoods operate at all times. During normal
blowing and standby, when the primary hood covers the converter
mouth, only 800 to 1200 Nm3/min are exhausted from the secondary
hood. When charging or pouring is in process, the gas volume
exhausted is increased to between 2200 and 2500 Nm3/min. These
volumes are sufficient to establish a good air flow pattern into
the hood exhaust duct and air curtain. Some gases, however, do
spill out of the front of the hood and rise into the converter
aisle. This occurs mainly during charging and pouring. The
secondary hood was observed to capture an estimated 30 to 50
percent of those gases not collected by the primary hood during
charging and pouring, and nearly all fugitives during normal
blowing and standby.
The design basis for the secondary hood gas treatment is
2000 ppm S02 concentrations range between 400 and 500 ppm S02.
These gases are mixed with the reverberatory furnace gases and
are scrubbed in an MgO absorption process (see attached report).
96
-------
to
CONVERTER A 5000 Nm3/min~j TO BAGHOUSE
AISLE EXHAUST B 3800 Nm3/minj THEN STACK
CONVERTER
'BUILDING ENCLOSURES^
(NOT TO SCALE)
KEY
A NORMAL BLOWING
AND STANDBY
B CHARGING AND
POURING
,AIR CURTAIN
PRIMARY HOOD
14m
(NOT TO SCALE)
AIR CURTAIN
A 800 to 1200 Nm/min
Tn
T0
EXHAUST B 2200 to 2500 Nm3/minj THEN STACK
0 Nm3/min } TQ MgQ ABSORBER
1200 NmJ/min
SECONDARY
HOOD EXHAUST
SECONDARY
HOOD
RADIANT
PRECOOLING
CHAMBER
CONVECTION
TUBES AREA
CHAIN CONVEYOR
14.9m
CONVERTER
HOOD (A 950 Nm3/min
EXHAUST f B 200 TO 300
15.2m(pLANT)DJ Nm3/m1n
4.1m
Figure B-l. Schematic of the Onahama converter emission control system.
-------
AIR CURTAIN
SLOT FOR
CRANE CABLE
SECONDARY
HOOD EXHAUST
TO MgO SCRUBBER
AIR CURTAIN
EXHAUST
TO BAGHOUSE
FEED HOPPER
PRIMARY HOOD
(OPEN)
TUYERE AIR
Figure B-2. Converter hooding arrangement.
98
-------
The air curtain across the slot in the secondary hood cap-
tures those hot gases which would normally pass through the
secondary hood slot. Three fans create the stream of air which
passes above the slot in the secondary hood and enters the cap-
ture duct on the opposite side of the slot. This "push/pull"
technique is almost 100 percent effective in collecting fugitive
which would normally escape through the slot. Only those gases
which spill out of the front of the hood remain uncaptured.
The gases collected by the air curtain range between 100
and 200 ppm SO2 . They are ducted to a baghouse for particulate
removal and then are discharged through a stack.
The converter aisle building exhaust completes the con-
verter fugitive emission control systems. The converter aisle
has been almost completely enclosed with sheet metal partitions.
The major effort involved separating the reverberatory furnace
building from the converter aisle. Only the major access doors
at either end and middle of the converter aisle remain- open.
The reverberatory furnace building is relatively free of SO2 as
a result of isolating it from the converter aisle. However, a
significant quantity of S02 remained uncollected at the top of
the converter aisle.
During normal blowing and standby, 5000 Nm3/min are ex-
hausted from the building. This volume of air is ducted to the
same baghouse which handles the air curtain exhaust. However,
each time an air curtain is activated, the building exhaust is
reduced by 1200 Nm3/min, the quantity used by the air curtain.
This system is not quite adequate for complete building ventila-
tion. A significant increase in the converter aisle exhaust
would probably be needed to clear the residual S02 which col-
lects at the top of the building. The residual S02 is not a
major problem and does not impair visibility from the converter
aisle crane cabs.
With three converters operating, one on standby and one
under repair, approximately 10,500 Nm3/min are exhausted from
the converter building. This results in a building air change
once every 5^ to 6 minutes. This is sufficient to maintain the
converter aisle work areas relatively free from any significant
S02 concentrations.
Mitsubishi (MI) Process:
Mitsubishi personnel provided information on their continu-
ous smelting process. The information provided confirmed that
reported in "Emerging Technology in the Primary Copper
Industry." The MI process is located at the Naoshima smelter.
We were not able to arrange a visit to Naoshima because a new
plant management was taking over responsibility for the smelter
the same week we made our visit.
99
-------
The MI process is a three furnace smelting system. A 65
percent copper matte is produced in the smelting furnace. Coal
is mixed with the concentrate to provide more uniform heat for
smelting, reduce the flame temperature required in the furnace,
and increase the slag fluidity. Supplementary oil fired burners
are also needed to heat the furnace. These are two changes from
the original intent of operating an autogeneous smelting
furnace. They have been made necessary because water cooling of
the furnace refractory was added to reduce refractory wear.
This loss of heat made supplemental fuel necessary.
Slag and matte from the smelting furnace flow by gravity in
a launder to the electric slag cleaning furnace. The copper
content of the slag is maintained at 0.5 to 0.6 percent Cu by
maintaining a reducing atmosphere in the slag cleaning furnace.
The slag then flows by gravity to the converter furnace.
The converter furnace produces anode copper which flows to
a holding furnace prior to anode casting. Slag from the con-
verter furnace is granulated separate from the slag cleaning
furnace slag. The converter furnace slag is then recycled to
the smelting furnace.
Mitsubishi has licensed their process to Gulf Western for a
65,000 metric ton per year smelter in Timmins, Ontario. This is
a 30 percent increase in capacity over the 50,000 mt/yr smelter
at Naoshima. Both smelters will be similar in that the concen-
trates processed contain very little arsenic (<100 ppm). The
Timmins, Ontario smelter, however, will process concentrate
containing up to 6 percent zinc and 5 percent lead. Conse-
quently, the particulate removal equipment will be much larger
than at the Naoshima smelter.
Mitsubishi is presently marketing the MI process. The
major advantages cited are: energy efficiency, low atmospheric
emissions, and no converter aisle. Eliminating the converter
aisle lowers the required smelter capital investment and
eliminates the fugitive emissions from crane operations.
100
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing}
1. REPORT NO.
EPA-600/2-80-079
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Control of Copper Smelter Fugitive Emissions
5. REPORT DATE
May 1980 issuing date
B. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Timothy W. Devitt
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
PEDCo Environmental, Inc.
11499 Chester Road
Cincinnati, Ohio 45246
10. PROGRAM ELEMENT NO.
1AB604
11. CONTRACT/GRANT NO.
Contract No. 68-02-2535
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Task Final: 3/7fi - 10/79 .
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report deals with fugitive emissions from copper smelting and with related
emission control measures. The study involved evaluation of the controls now used
in the copper smelting industry and development of suggestions for alternative control
devices and practices.
A brief overview of copper smelting processes is followed by a more detailed
analysis of the conventional processes identifying portions of the operating cycle
that produce fugitive emissions. Emphasis is placed on Fierce-Smith Converting,
which is one of the major emission sources in copper smelting. Some alternate
processes now in limited used in the U. S. are described including estimations of
fugitive emissions from these conventional and alternative copper smelting processes.
A specific report on the utilization of the Hoboken Converter is being prepared
at the time of this report. The USEPA should be contacted if a copy of this report
is desired.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
:. COSATI Field/Group
Air Pollution Control
Copper Smelting
Fugitive Emissions
Copper Smelting
Pierce-Smith Converting
Hoboken Converters
8. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report}
Unclassi f i'pd
21. NO. OF PAGES
113
20. SECURITY CLASS (Thispage)
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
101
V-SWEV "NTS: :» CE •9SC-657-146/5681
------- |