United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
EPA 600 2-80-022
January 1980
Research and Development
Evaluation of
Paul Bergsoe & Son
Secondary Lead
Smelter
-------
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-600/2-80-022
January 1980
EVALUATION OF PAUL BERGSOE & SON
SECONDARY LEAD SMELTER
by
Richard T. Coleman, Jr. and Robert Vandervort
Radian Corporation
Austin, Texas 78766
Interagency Agreement No. 78-D-X0309
Project Officers
James A. Gideon
Division of Physical Science and Engineering
National Institute for Occupational Safety and Health
Cincinnati, Ohio 45226
Alfred 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
-------
DISCLAIMER
This report has been reviewed by the National Institute for Occupational
Safety and Health (NIOSH) and the U.S. Environmental Protection Agency (EPA),
and approved for publication. Approval does not signify that the contents
necessarily reflect the views and policies of these agencies nor does mention
of trade names or commercial products constitute endorsement or recommendation
for use.
ii
-------
FOREWORD
When energy and material resources are extracted, processed, converted,
and used, the impacts on occupational and environmental health often reauire
that new and increasingly more efficient control methods be used. The Divi-
sion of Physical Science and Engineering of NIOSH and the Industrial Environr
mental Research Laboratory - Cincinnati (lERL-Ci) of EPA assist in deve-
loping and demonstrating new and improved methodologies that will meet these
needs both efficiently and economically.
This report presents the findings of an investigation performed to
obtain data concerning fugitive and workroom emissions from secondary lead
smelters. The results are being used within both NIOSH and EPA as part of
a larger effort to define the potential workplace/environmental impact of
emissions from this industry segment and the need for improved controls.
The findings will also be useful to other agencies and the industry in
dealing with control problems. Either the Metals and Inorganic Chemicals
Branch of the USEPA or the Division of Physical Science and Engineering of
NIOSH should be contacted for any additional information desired concerning
this program.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
Walter Haag
Director
Division of Physical Science and Engineering
NIOSH
Cincinnati
111
-------
ABSTRACT
The present report presents the results of an interagency study of the SB
battery smelting furnace. The study was conducted by Radian Corp., Austin,
Texas, under contract to the National Institute for Occupational Safety and
Health (NIOSH) and the Environmental Protection Agency (EPA). The study was
performed at the Paul Bergsoe and Son secondary lead smelter in Glostrup,
Denmark in September, 1978.
During the test period, the smelter feed materials consisted of approx-
imately 12.6 percent(w) polyproplyene case and 12.6 percent (w) hard rubber
case whole batteries. The remainder of the lead bearing feed materials were
crushed battery plates and a small amount of lead scrap. The average pro-
duction rate for the test period was 70.5 metric tons of lead per day.
The tests conducted indicated that the controlled stack emissions were
as follows:
. Lead - 0.046 to 0.056 kg/hr
• Antimony - 0.52 to 0.54 kg/hr
• Arsenic - 0.0005 to 0.0013 kg/hr
• Chlorine - 1.6 to 7.1 kg/hr
. Sulfur - 6.9 to 9.1 kg/hr
Employee exposures were maintained below 100 jjg/m^ in all areas of the
smelter. This low exposure is due to the exemplary engineering and work
practice controls. Yard sprinkling, washdown procedures, and good general
housekeeping efforts also helped reduce the levels of lead in and around the
workplace.
IV
-------
CONTENTS
Disclaimer ii
Foreword iii
Abstract iv
Figures viii
Tables x
Conversion Chart xii
Acknowledgments xiii
1. Introduction 1
2. Plant Description 2
SB battery smelting furnace 2
Furnace operation 5
Furnace charging 6
Operating parameters 7
Flash agglomeration furnace 8
Plant layout 10
3. Summary of Results 14
4. Source Characterization 18
Smelter operating conditions 18
Feed characteristics 18
Energy consumption 20
Production data 20
Furnace operation 22
High volume air monitoring 22
Stack sampling 24
Description of sampling locations 24
EPA Method 5 ; 26
Wet electrostatic precipitator (WEP) 30
Stack emission factors 33
Material flow 34
Feed characterization . 34
Product samples 35
Elemental partitioning 36
-------
CONTENTS (Continued)
5. Control Technology Assessment 37
Description of equipment and controls 37
Receipt of raw materials 37
Charge storage and preparation 37
SB furnace charging facilities 39
SB furnace operating area 39
SB furnace integrated ventilation system 43
Flue dust handling 45
Description of emission sources and potential exposure 45
Materials handling emissions 45
Charging emissions 48
Slag tapping 48
Tuyere punching 49
Finished metal tapping 49
Afterburner slag port 51
Agglomeration furnaces 51
Baghouse bag replacement 51
Engineering control evaluation 51
Raw materials handling 52
SB furnace integrated ventilation system 55
SB furnace charging hood (Hood I) 58
Slag tapping hoods (Hoods A,B,C,D) 58
Secondary slag tapping hoods (Hoods E and F) 62
Finished metal tapping hood (Hood G) 62
Finished metal ladle cooling hood (Hood H) 65
Agglomeration furnace ladle hood (Hoods J and K) 68
Other industrial hygiene considerations 68
Employee work schedules 68
Personal protective equipment 68
Employee hygiene 69
Biological monitoring 69
Workplace air monitoring 69
Noise level measurements 69
Control critique 69
6. Other Process and Controls 73
Rotary furnace smelting 73
Description of equipment and controls 73
Description of emission sources and potential exposures 78
Engineering control evaluation 81
Other industrial hygiene considerations 89
Control critique 89
vi
-------
CONTENTS (Continued)
Pot induction furnace 91
Description of equipment and controls 91
Description.of emission sources and potential exposures 91
Engineering control evaluation 93
Control critique 93
Appendix. Blood/Lead Data Supplied by Bergs^e Management 94
vii
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FIGURES
Number Page
1 General process flowsheet for the secondary lead smelter
industry 3
2 Whole battery smelter furnace and flue gas treatment system 4
3 Flash agglomeration furnace 9
4 Plot plan 11
5 Stack cross-section 25
6 EPA 5 sampling train 27
7 Schematic of the integral WEP sampling train 31
8 Wet electrostatic precipitator 32
9 Overview of SB furnace building and charge storage and prepa-
ration building 38
10 Furnace charging hood (Hood I) 40
11 Key to local exhaust ventilation hoods associated with SB
furnace and agglomeration furnaces 41
12 SB furnace ground level work area, SB furnace building 42
13 Overview of exhaust ventilation controls for the tapping of
slag and finished metal 44
14 Agglomeration furnace and ladle hood (Hoods J and K) 46
15 Detail of slag tap hole plug and tuyere design 49
16 Key to ventilation system test points 56
17 Face velocity measurements - furnace charging hood (Hood I) 60
18 Side elevation - slag tapping hood (Hoods A,B,C,D) 61
viii
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FIGURES (Continued)
Number Page
19 Front elevation - slag tapping ladle (Hoods A,B,C,D) 63
20 Secondary slag tapping hood (Hoods E and F) 64
21 Front elevation of finished metal tapping hood (Hood G) 66
22 Finished metal ladle cooling hood (Hood H) 67
23 Rotary furnace smelting and charge storage and preparation
building 74
24 Close-up of charge container resting deck, roll-up door,
and detail of charge container 76
25 Rotary furnace charging and tapping controls 77
26 Overview of rotary furnace ventilation controls and key
to ventilation system test points 84
27 Finished metal ladle cooling hood 88
28 Pot induction furnace hood 92
PLATES
1 12
2 12
3 13
4 13
ix
-------
TABLES
Number Page
1 Typical Feed Makeup for SB Smelting Furnace Charge 6
2 Approximate Elemental Distribution in Smelter Exit Streams 15
3 Stack Emissions Determined Using WEP Train 16
4 Typical Charge Materials During the Test Period 19
5 Reported Furnace Feed Data for the Test Week 20
6 Energy Consumption Data 21
7 Reported Production Data for the Week of September 24, 1978 21
8 Reported Production Data for a 91-Day Campaign 21
9 Operating Parameters Recorded During the Characterization Tests .... 23
10 Hi-Vol Area Sampling Results 24
11 Traverse Points Measured from the Inside Wall at the Sampling
Port 26
12 EPA Method 5 Results 28
13 Lead Particulate Emissions Test Results 29
14 Gaseous Sulfur and Chlorine Emission Test Results 29
15 Total Lead, Arsenic, and Antimony Emission Test Results 33
16 Stack Emission Factors for the SB Battery Smelting Furnace 34
17 Average Feed Material Composition 35
18 Product Stream Analyses 36
19 Elemental Partitioning in the SB Smelting Furnace 36
20 Breathing Zone, Lead-in-Air Concentrations Associated with SB
Furnace Operations 53
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TABLES (Continued)
Number Page
21 Work Area Lead-in-Air Concentrations Associated with Operation
of the SB Furnace ................................................. 54
22 Results of Tests in SB Furnace and Agglomeration Furnaces
Ventilation Systems ........................ . ............ ... ....... 57
23 Work Area Arsenic-in-Air Concentrations Associated with Operation
of SB Furnace ...................... . .............................. 59
24 Results of Noise Measurements Made in Association with SB Furnace
Operations ............................. . .......................... 70
25 Lead and Antimony-in-Air Concentrations Associated with Rotary
Furnace Operations ................................................ 32
26 Results of Tests in Rotary Furnace Ventilation System. .... .......... 85
27 Results of Noise Measurements Made in Association with Rotary
Furnace Operations ........ . ...... . ................................ 90
xi
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CONVERSION CHART
To convert from
To
Multiply by
British thermal unit (Btu, International Table)
Btu/hour
Btu/second
Btu/ft2-hr-deg F (heat transfer coefficient)
Btu/ft2-hour (heat flux)
Btu/ft-hr-deg F (thermal conductivity)
degree Fahrenheit (°F)
degree Rankine (°R)
foot
foot2
foot/second2
foot2/hour
footz/second
foot3
gallon (U.S. liquid)
horsepower (550 fflbf/s)
inch
inch of mercury(60°F)
inch of water(60°F)
inch2
inch3
kllocalorie
kilogram-force(kgf)
psi
ton (short.2000 Ibm)
watt-hour
joule(j)
watt(W)
watt(W)
j oule/raeter 2-second-kelvin( J/m2 • s -K)
joule/meter2-second(J/m2«s)
j oule/meter-second-kelvln( J /m- a -K)
kelvin(K)
kelvin(K)
meter(m)
meter2(m2)
meter/second 2(m/s 2)
meter 2/aecond(m2/s)
meter 2/second(in2/s)
meter'do3)
ip.eter3(m3)
watt(W)
meter(m)
pascal(Pa)
pascal(Pa)
meterz(m2)
meter3(m3)
joule(J)
newton(N)
pascal(Fa)
kilogram(kg)
joule(J)
1.0550559
2.9307107
1.0550559
5.6782633
3.1545907
1.7307347
E
E
E
E
E
E
*„ • (*„ +• 459
K. c
tR - *H/1.8
3.0480000* E
9.2903040* E
3.0480000* E
2.5806400* E
9.2903040* E
2.8316847 E
3.7854118 E
7.4569987 E
2.5400000* E
3.37685 E
2.48843 E
6.4516000* E
1.6387064* E
4.1868000* E
9.8066500* E
6.8947573 E
9.0718474* E
3.6000000* E
+ 03
- 01
+ 03
+ 00
+ 00
+ 00
.67)/1.8
- 01
- 02
- 01
- 05
- 02
- 02
- 03
+ 02
- 02
+ 03
+ 02
- 04
- 05
+ 03
+ 00
+ 03
+ 02
+ 03
-------
ACKNOWLEDGMENTS
The authors would like to thank the Bergs^e management and workers who
were most cooperative during this study. We would also like to thank Dr.
Thomas Mackey for his help in arranging our meeting in Denmark.
We would also like to commend the members of the sampling and analytical
team who helped perform this characterization study. Special thanks to:
Michael R. Fuchs David J. Burton
Lawrence J. Holcombe Jay R. Hoover
C. William Arnold Guy M. Crawford
Robert M. Mann Cheryl M. Carter
Barbara J. Bolding David A. Hayes
xiii
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SECTION 1
INTRODUCTION
As part of an interagency effort, the Control Technology Assessment
Branch of NIOSH and the Metals and Inorganic Chemicals Branch of EPA have
performed a characterization of new secondary lead smelting technology.
The processes characterized offer potential solutions to major occupational
and environmental problems associated with secondary crude lead production.
Two major processes were studied: special battery (SB) smelting and flash
agglomeration of flue dust. The study was performed at the Paul Bergsoe
and Son smelter in Glostrup, Denmark.
This study provided both EPA and NIOSH an opportunity to cooperate on
a test program where measurements of both stack and workplace/fugitive
emissions were made. Fugitive emission rates were not measured directly in
this study. However, the concept of using workplace lead-in-air levels as
one measure of fugitive emission control effectiveness while recording pro-
cess variables and stack emission data may help in future efforts to pro-
tect both the workers and the environment. Changes in a process variable
or a stack emission rate may serve as a useful indicator that a particular
agent may present a workplace contamination problem. This study developed
a coordinated, combined EPA/NIOSH test procedure for process character-
izations. Future test programs may expand on this one to include direct
measurements of fugitive emission rates and fugitive emission control effi-
ciency.
In Section 2.0, a description of the SB battery smelting furnace is
presented. Section 3.0 is a summary of the major results of the study.
Section 4.0 presents the detailed results of the source characterization
tests. Section 5.0 discusses the results of the control technology assess-
ment. Section 6.0 presents additional results gathered for the control
technology assessment. The rotary furnaces and electric induction furnace
were evaluated in this part of the study.
-------
SECTION 2
PLANT DESCRIPTION
Secondary lead smelting involves three major operations: scrap pre-
treatment, smelting, and refining. Figure 1 outlines the material flow in
a typical secondary lead smelter and lists the major processes, raw mater-
ials, and products. SB smelting is an important process because it elim-
inates the battery decasing step when whole batteries comprise a portion of
the furnace charge. During the test period, whole batteries comprised 40
percent of the lead-bearing charge. In addition, since flue dust agglom-
eration is an integral part of the SB smelter, a major part of the smelter
fugitive dust emissions are eliminated. It is important to note, however,
that SB smelting alone is applicable only for the production of crude lead.
Additional refining processes are required to produce soft lead, lead ox-
ide, or lead alloys.
SB smelting incorporates both environmental emission control and occu-
pational health features in its design. Plant layout, raw material storage
and handling, process and hygiene ventilation, housekeeping, process con-
trol, and flue dust agglomeration are all included in the smelter design.
Also, the SB furnace is operated at conditions producing minimum emissions.
This approach has been implemented by Paul Bergsoe and Son A/S of Glostrup,
Denmark where environmental and occupational health regulations forced
modernization of their lead smelter.
SB BATTERY SMELTING FURNACE
The SB battery smelting shaft furnace has a rectangular cross section
unlike most cylindrical secondary lead blast furnaces used in the United
States. The construction is similar to a primary lead blast furnace. Fig-
ure 2 is a diagram of the furnace and associated gas treatment system. The
furnace is constructed so as to isolate the charging floor from the bottom
of the furnace. Additionally, the raw material storage and handling area
is isolated in an enclosed building. Thus, only the front-end loader oper-
ator charging the furnace works in a "dirty" area. The front-end loader
does have a filtered air supply. In addition, the top of the blast furnace
is provided with local exhaust ventilation to minimize fugitive emissions.
At the bottom of the furnace, local exhaust ventilation is provided
for the four slag taps and the lead ladles. There are two rows of tuyeres,
one on either side of the furance, designed to use air preheated to 500°C.
The tuyeres have special covers which minimize emissions during punching.
-------
5MELTIK6
H£FIH1 KG/CAST I KG
Drosses Residue
Oversize Scrap ~
Residues
on Scrap
Lead Sheathed
Cable and Mire
High Lead
Scrap '
Oxides, Flue Ousts.
Mixed Scrap (Untreated) '
±z
Battery
Oecaslng
Rotary /Tube
Sweating
Fuel
Reverberatory
Sweating
1
H
"
*\
Pure Scrap
70-1312-3
Figure 1. General process flowsheet for the secondary lead
smelting industry.
-------
-LEAD WCU.
STREAM
No.
SlM TAP
LfXD *R.i VENT
nnmuef TOP
SANlTUtf VENT
to
STREAM VAMC
©+
SEC.
TAf KXMT
process GAS
*
COHR/MCD
VENT
(*See Figure 13 for new
lead well arrangement)
Figure 2. Whole battery smelter furnace and flue gas treatment system.
-------
The local exhaust ventilation air and process flue gases are mixed and
all gases pass to four baghouses (at 100-125°C). The baghouses are a Swedish
design using felted polyester cloth. The dust is collected on the outside
of the bag and only a mild cleaning air stream is required to dislodge the
dust. This reportedly gives the bags a longer life. The baghouses were
designed to operate with three running and one spare. During the test
period, all four were running. The air-to-cloth ratio with four baghouses
operating is 34.5 m3/hr/m2 (1.88 ft3/min/ft2). The effective cloth area is
4720 m2 for four baghouses. Typical pressure drop across the baghouse is
150 mm (^6 inches) water gauge.
The collected dust is conveyed in an enclosed screw conveyor system to
one of two small flash agglomeration furnaces. The flash agglomerator
furnace is oil fired and consumes approximately 7.7 liters of oil per hour.
In this patented process, the dust is melted, reducing its volume by about
80 percent. The agglomerated dust represents only 2 or 3 percent by weight
of the furnace charge. This reduction in volume permits an increased
throughput of raw material and increased production per square foot of
furnace cross-section. Agglomerating the dust also reduces the dust load
circulating in the gas cleaning system because the agglomerated dust is not
entrained from the top of the furnace.
The smelter area is paved and is wetted and swept periodically. This
practice minimizes fugitive emissions normally caused by the wind blowing
dry lead dust in the yard. This wash water is collected, combined with
the acid drainage from cracked batteries stored in the yard, and is finally
treated using a soda ash precipitation process. The treated effluent is
discharged to the municipal wastewater treatment facility. The sludge is
withdrawn approximately once every two weeks and is charged back to the
furnace for additional recovery of metals.
The smelter is serviced by two additional sewer collection systems,
one for rainfall and one for sanitary sewage. The rainfall collected is
used as washdown water for the smelter yard. Additional makeup cooling
water is obtained from the municipal water supply. This water is
softened in an ion exchange unit before use. Sanitary sewage is discharged
directly to the municipal collection system.
Furnace Operation
The operation of the SB furnace results in low stack and fugitive lead
emission rates. The relatively low blast air rate (VJ500 Nm3 air/hr)t and
large furnace cross-sectional area (4.0 m2 at the tuyeres) results in a low
gas velocity. This combined with the low furnace top temperatures (M.OO°C)
and the absence of loose flue dust in the charge result in a low lead dust
generation rate. The large furnace cross-section and small production rate
allows the charge material to descend slowly through the furnace shaft.
t Nm = normal cubic meters, 0°C, 760 mm Hg.
-------
Thus the charge heats slowly and is not hot enough at the top of the furnace
to generate lead fume.
This slow heating also prevents the rubber and polypropylene case
material from "burning thru." Burn-thru could occur when the charge material
is ignited throughout the furnace shaft rather than only in the smelting zone.
This occurs more readily in the SB furnace than in conventional blast furnace
because the rubber or polypropylene case material is present. It is there-
fore very important to control the furnace temperature both from an operating
and an environmental viewpoint to reduce fuming at the charging port .
Furnace Charging
In order to help maintain constant temperature in the furnace, the feed
is carefully bedded on the chargeroom floor. A layer of coke is spread on the
floor first, followed by recycle slag, batteries, plates, scrap iron and other
feed materials. By doing this, each bucket of material charged to the furnace
contains roughly the right amount of coke. This practice maintains a homo-
geneous mixture of material in the furnace and helps avoid hot spots.
Each furnace charge during the test period contained roughly the same
ratio of the materials shown in Table 1. A front end loader is used to spread
the feed materials on the chargeroom floor. A large floor scale is used to
weigh the front end loader with a full bucket. The measurement is fed to the
mini-computer which monitors the smelter operations. The weight of the empty
front end loader is subtracted and the charge weight is recorded. A very
accurate measurement of the charge blend is possible using this technique,
typically within 1 to 2 percent of the target on major components (batteries,
plates, etc.) and within 4 to 5 percent on the minor components.
TABLE 1. TYPICAL FEED MAKEUP FOR SB SMELTING FURNACE CHARGE
Feed material
Approximate
weight percent
Percent of lead
bearing charge
Whole batteries
-polypropylene case
-hard rubber case
Battery plates
Agglomerated dust } , ,
Drosses j
Return slag
Coke
Scrap iron
FeO (mill scale)
CaC03
Total
12.6
12.6
31.5
:ery mud) 3'2
22.1
5.7
1.9
6.3
0.9
100.0
20.0
20.0
50.0
5.0
5.0
100.0
-------
Operating Parameters
At present, the Bergs^e smelter does not have permission to dispose of
the furnace slag in a landfill. As a result, the furnace is being operated
in a slightly different fashion than it would if the slag could be dumped.
At present, the furnace slag reportedly contains between 1.5 and 3 weight
percent lead. The samples gathered during this study assayed approximately
0.55 weight percent lead. All of the slag is stockpiled and the portion
with a high lead content is recycled to the furnace. When a dumping permit
is obtained, additional CaCOa will be added to the charge to maintain the
slag lead content below 2.0 weight percent.
Adding more CaCOs will raise the slag melting point and make control of
the SiOa/FeO ratio more important. In the past, accretions (freezing) at the
tuyere level in the furnace have been a problem. In some of the early cam-
paigns, large accretions of an iron-containing material had to be removed
from the furnace. An analysis of similar accretions taken from the SB fur-
nace constructed at Britannia Lead Co. in Gravesend, England showed that
the following elements were present as expected: Al, Si, Pb, S, Ca, and Fe.
However, the major crystalline species have not, as yet, been identified.
Bergstfe operators appear to have eliminated the problem by reducing the iron
feed to the furnace. Blast air oxygen enrichment was also added and report-
edly helped eliminate the problem. The accretion problem is not expected to
recur when additional CaCOs is added because of the reduction in iron content
of the feed materials.
Scrap iron and mill scale (FeO) are added to the furnace so that a PbS-
FeS matte forms between the lead bullion and slag in the furnace. Most of
the sulfur input is trapped in this matte. At present, the matte is being
stored on-site because of its high lead content (^8%). It must either be
sold to a primary lead smelter or disposed of in a protected landfill.
Recovery of the matte lead content at a secondary lead smelter is not
possible because of the sulfur. Sulfur dioxide emission controls would be
required for any furnace processing the matte. A primary lead smelter,
however, could combine this material with the normal lead sulfide materials
they process.
Oxygen enriched air is used in the SB furnace. Blast air is preheated
to 500°C and then mixed with oxygen prior to entering the furnace. Preheat-
ing the air reduces the amount of coke required in the furnace and allows
smaller blast air rates to be used. As mentioned earlier, this helps re-
duce dust generation in the furnace. Blast air pressure at the tuyeres
ranges from 800 to 1200 mm H20. The blast air rate is typically between
3200 and 3700 Nm3/hr with between 60 and 115 Nm3/hr of oxygen added. These
rates correspond to a production rate of between 62 and 74 metric tons Pb
per day.
-------
FLASH AGGLOMERATION FURNACE
The flue dust generated by smelting automobile batteries and battery
manufacture scrap melts at approximately 400 to 900°C (750 to 1650°F).
This low melting point makes flash agglomeration of flue dust possible.
Dusts with higher melting points cannot be agglomerated using this tech-
nique without causing the low melting materials to volatilize. A special
furnace was designed to take advantage of this property so that dust hand-
ling could be completely avoided.
At most secondary lead smelters, it is common practice to return flue
dust directly to either the blast furnace or a reverberatory furnace. A
considerable amount of this dust is entrained in the furnace flue gas sys-
tem. Agglomerating the flue dust prevents entrainment, thus reducing the
load on the baghouse and improving its performance.
The Bergsoe smelter has two agglomeration furnaces serving the four SB
furnace baghouses. Figure 3 is a diagram of a flash agglomeration furnace.
The agglomeration furnace is fed directly from the baghouse dust hoppers
via screw conveyor. The dust drops onto the furnace hearth where it melts
almost instantaneously upon contact with an impinging flame. The liquid
runs down the sloping hearth, through a permanently open taphole and into a
cast iron vessel where it solidifies. This completely eliminates handling
of the dust, the associated occupational hazard, and fugitive emissions
from flue dust storage piles provided that the agglomeratged dust is stored
indoors.
Tipping the solidified contents of the cast iron vessels onto the
floor is usually sufficient to break the material into lumps suitable for
recharging to the blast furnace. It is simply mixed with coke and flux
and loaded into the top of the blast furnace along with other charge mater-
ials .
Since the agglomeration furnace produces a product which is both great-
ly reduced in volume and which does not create a significant recycle of re-
entrained dust from the furnace to the baghouse, additional material can be
charged to the furnace, thus increasing the smelting rate. This is one
economic justification for the agglomeration furnace.
A contamination of the flue dust also takes place. Lead chloride
forms as the polyvinyl chloride battery plate separators are smelted. Lead
chloride is more volatile than other oxide materials in the furnace. Re-
circulating the flue dust causes lead chloride to preferentially volatilize
in the furnace, further, increasing the chlorine content of the flue dust.
Flue dust which has accumulated a large percentage of chlorine can be ei-
ther leached to remove the chlorine, or used as a fluxing agent in another
part of the smelter.
-------
PROCESS VENT
BAGHOUSE-
DUST HOPPER.
BUfLNER.
SCREW
CONVEYOR.
rf&f&s£&^^
AGGLOMERATION
FUKA/ACE
SLOPED HEARTH
MOLTEN DUST
COOLING /T&A NSPORTA 77CW
Figure 3. Flash agglomeration furnace.
0225281
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PLANT LAYOUT
A plot plan of the new Bergs^e smelter is shown in Figure 4. The old
lead smelter, the lead refinery, the small cast iron department, the copper
department, and the other small smelting operations are located between 100
and 400 meters southwest of the new smelter. The old smelter was built in
the 1930's. Construction on the new smelter began in 1973 and the initial
startup occurred in 1975.
The SB furnace is located in the building labelled #1 on Figure 4. As
mentioned earlier, the furnace building isolates the top of the furnace where
the charging takes place from the work area on.the first floor. Plate 1 shows
the front end loader charging material to the furnace top. The large hood
over the charge area captures emissions escaping the furnace top. Plate 2
is a view of the outside of the building looking east. The SB furnace build-
ing is on the left. The afterburner chamber can be seen between the building
and the four large baghouses. The two small agglomeration furnaces are located
in front of the baghouses. Plate 3 shows the tapping area on the first floor
of the SB furnace building. Plate 4 is a view of the two agglomeration furnaces.
As shown in Figure 4, the SB furnace and the two short rotary furnaces
located in Building #3 both discharge to a common stack. The rotary furnaces
were not operating during the SB furnace test period.
Raw materials are stored in concrete bins in Building #2 in Figure 4.
Building #2 also contains the charge bedding area. Building #2 is not large
enough to contain all of the raw materials because of the irregular receipt
of scrap material. As a result, several large piles of plates, unbroken
batteries, and clean lead scrap are stored to the west of Buildings #1 and #2.
The small sodium carbonate water treatment plant is located between the
old and new smelters to the south of Building #1. As can be seen in Figure 4,
the smelter fenceline is 200 meters east southeast from the SB furnace build-
ing. This is the closest point from smelter to fenceline. The
prevailing winds are from either the west or west northwest.
10
-------
Figure 4. Plot plan
-------
PLATE 1. Front end loader delivering charge
to top of SB Furnace.
PLATE 2. View of smelter building and baghouse.
L2
-------
PLATE 3. Slag tapping area,
PLATE 4. View of agglomeration furnace,
13
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SECTION 3
SUMMARY OF RESULTS
In this section, the results of the NIOSH and EPA source characteriza-
tion studies are summarized. The purpose of the testing performed for this
program was to characterize the operation of and emissions from the com-
bined SB smelting and flue dust agglomeration furnaces. The source char-
acterization included: 1) an analysis of the smelter feed materials, 2) a
description of the furnace operation, 3) a determination of the flows of
lead, antimony, arsenic, chlorine, and sulfur, 4) measurement of stack
emissions, 5) calculation of an emission factor, 6) measurement of lead-in-
air levels in the smelter yard, 7) workplace and personal monitoring, 8)
evaluation of ventilation and other employee exposure control systems, and
9) observation and evaluation of work practices and personal protective
equipemnt.
The major results are:
• The smelter feed consisted of the followng materials:
Whole Batteries
-polypropylene case
-hard rubber case
Battery Plates
Agglomerated Dustlor battery mud]
Drosses -*
Return Slag
Coke
Scrap Iron
Mill Scale (FeO)
CaC03
Total
The total input materials contained an average of 79 metric tons
lead, 1.5 metric tons antimony, 29 kilograms arsenic, 0.1 metric
tons chlorine, and 2.6 metric tons sulfur per day.
• During the test period, these five elements were distributed in
the smelter output materials as shown in Table 2:
14
-------
TABLE 2. APPROXIMATE ELEMENTAL DISTRIBUTION IN SMELTER EXIT STREAMS
Percent of total incoming flow
Output stream
Lead bullion
Lead stone (matte)
Stack Gas
Total
(Estimated accuracy of
Pb
87.7
0.90
0.0025
89
elemental
Sb
98.5
11.2
0.84
110
flow rates
As
10.4
75.7
0.07
86
is +20%.)
Cl
12.8
36.8
75.8
125
S
0.14
98.0
7.2
105
• The chlorine content of the agglomerated flue dust averaged
25 percent by weight. This demonstrates the accumulation of
chlorine in the flue dust collection system.
The lead particulate emission rates based on the EPA Method
5 test results were:
-September 26, 1978 0.056 kg Pb/hr
-September 27, 1978 0.046 kg Pb/hr
Total stack lead emissions, based on the wet electrostatic precipi-
tator (WEP) experiments, ranged between 0.042 and 0.12 kg Pb/hr.
The stack lead particulate emission factors (after control) based
on the WEP experiments were:
-September 26, 1978 14 g Pb/metric ton Pb product
-September 27, 1978 42 g Pb/metric ton Pb product
Stack chlorine emissions ranged from 1.6 to 7.1 kg/hr.
• Stack gas concentrations ranged from 39 to 54 ppm sulfur
during the test. This corresponds to sulfur emission rates
of 6.7 and 9.1 kg S/hr.
• Total stack antimony emissions ranged between 0.52 and 0.54
kg/hr.
• Total stack arsenic emissions ranged between 0.0005 and
0.0013 kg/hr.
15
-------
Only one high volume area sampler was run on each of the
two test days. The hi-vol was placed underneath the bag-
house nearest the east fenceline (see Figure 4). It was
approximately four meters from the east agglomeration furnace
and 80 meters from the east fenceline. The two twenty-four
hour average lead-in-air levels were:
-September 26, 1978 12 yg Pb/m3
-September 27, 1978 18 yg Pb/m3
Stack emissions based on the WEP tests are presented in
Table 3:
TABLE 3. STACK EMISSIONS DETERMINED USING WEP TRAIN
Element
Lead
Antimony
Arsenic
Chlorine
Sulfur
September
Concentra-
tion
(yg/Nm3)
1010
4390
4
13300
55700
26, 1978
Emission
rate
(kg/hr)
0.12
0.54
0.0005
1.6
6.7
September
Concentra-
tion
(yg/Nm3)
350
4370
11
59500
77100
27. 1978
Emission
rate
(kg/hr)
0.04
0.52
0.0013
7.1
9.1
The engineering and work practice controls of employee exposure
at this smelter are exemplary. The effectiveness of this system
of controls is evidenced by the control of employee exposures
to lead in all work activities associated with the SB furnace
to approximately 100 yg/m3 or less.
In general, the local exhaust ventilation systems provided for
the SB furnace are well designed and maintained. They provide
good enclosure of emission sources, vigorous hood face and
duct transport velocities, access openings and mobility to
allow efficient performance of routine work.
Yard sprinkling and washdown procedures appeared to greatly
minimize entrainment of dust into the air, tracking of muddy
materials into other work areas, and splashing of mud on
employee clothing and plant equipment.
Washdown procedures employed in the SB furnace operating area
did maintain floors in dust free and clean condition.
16
-------
• " The SB furnace process control room was found to be contaminated
with lead (38 to 54 yg Pb/m3).
The specific measurements and results are presented along with the descrip-
tion of the smelter operation in the following sections.
17
-------
SECTION 4
SOURCE CHARACTERIZATION
SMELTER OPERATING CONDITIONS
The SB furnace operated steadily during the entire test period. The
furnace was being operated somewhat differently than normal because at pres-
ent all slag generated by the furnace must be stockpiled and a portion recy-
cled. Permission to dump the slag in a landfill has not yet been obtained.
The chalk (CaCOs) feed to the furnace was reduced slightly. The slag still
contained 0.55 percent lead by weight. This is well within the range of
normal operation, during which the furnace slag typically contains less than
2 percent lead.
This lower chalk feed rate makes the slag less viscous and allows the
slag temperature to be maintained at approximately 100°C lower than normal.
The lower operating temperature makes the furnace operation slightly easier
from an environmental viewpoint because the top temperature can be main-
tained between 100 and 140°C more easily. This may result in lower fume
generation at the furnace top and correspondingly lower fugitive emissions.
Feed Characteristics
The Bergs^e smelter does not normally receive a large quantity of poly-
propylene-eased (poly) batteries in their feed. S-oiae poly batteries were
stockpiled for this test. The day of the testing (26 September), the poly
batteries were added to the SB furnace charge. The poly batteries comprised
approximately 12.6 weight percent of the total furnace charge during the
tests. This corresponds to 20 percent of the lead-bearing charge to the
furnace. The approximate furnace feed on September 25, 26, and 27 consisted
of the following materials:
Whole batteries
- polypropylene casre 12.6% (weight)
- hard rubber case 12.6
Battery plates
Agglomerated dust (or battery mud)
Drosses
Return slag
Coke
Scrap iron
Mill scale (PeO)
CaC03
Total
18
-------
The furnace feed is prepared (bedded) using a front end loader. A layer
of coke is first spread on the floor of the charge bedding area (see Figure 4)
The other components of the charge are then spread on top of the coke. This
procedure results in an even distribution of coke in each bucket of feed de-
livered to the furnace.
The target for each charge is 20 metric tons of lead bearing material.
Between three and four charges are required to match the SB furnace produc-
tion. An attempt was made to record the weight of all materials charged to
the furnace during the test. However, only a portion of the individual
charge data was made available by the Bergs^e management. Table 4 presents
the data recorded for five of the charges fed to the furnace during the test.
Note how closely to the target of 20 metric tons of lead bearing material
each charge is prepared.
TABLE 4. TYPICAL CHARGE MATERIALS DURING THE TEST PERIOD
(Weight in kilograms)
Charge date/time
Feed material
Whole batteries
- poly
- rubber
Battery plates
Agglomerated dust
Drosses
Battery mud*
Return slag
Coke
Scrap iron
Mill scale
CaC03
Subtotal
Lead scrap**
Total
Target
8,000
10,000
1,000
1,000
7,000
1,800
600
2,000
300
31,700
_
31,700
9/25
1200
7,590
9,930
2,050
6,810
1,770
640
2,030
660
31,480
31,480
9/26
0750
4,180
4,260
9,700
1,140
1,260
7,170
1,760
500
2,390
320
32,680
32,680
9/26
1200
4,550
4,260
9,850
840
980
6,760
1,790
660
2,060
280
32,030
4,860
36,890
9/27
0300
4,500
3,650
9,820
620
930
7,060
1,900
460
1,880
80
30,900
30,900
9/27
0830
4,060
3,920
10,370
600
1,180
7,300
1,750
930
2,440
190
32,740
32,740
*Charged instead of Drosses and Agglomerated dust
**Total lead scrap fed to the furnace during test
Table 5 lists the 'data provided by the Bergs^e management for the week
of the test. It was stated that only 4,860 kg of the lead scrap listed in
Table 4 was charged during the two test days. This could not be verified.
The lead scrap needs only to be melted in the SB furnace; no smelting is
required.
19
-------
TABLE 5. REPORTED FURNACE FEED DATA FOR THE TEST WEEK
(Weight in kilograms)
Lead-bearing
material
Whole batteries
Battery plates
Battery mud
Agglomerated dust
Lead drosses
Subtotal
Lead scrap
Total
Weekly
Average
265,440
269,330
48,850
16,450
17,440
617,510
71,450
688,960
Daily
average
37,920
38,476
6,979
2,350
2,491
88,216
10,207
98,423
Percent of
charge
38.5
39.1
7.1
2.4
2.5
89.6
10.4
100.0
Energy Consumption
There are seven separate items which must be considered with regard to
energy consumption per ton of lead in the SB battery smelting system. Table
6 lists each of these items and the corresponding fuel or electrical power
consumption.
These values are comparable to a 1 meter (40 inch) cylindrical blast
furnace which is reported to use approximately 74 kg coke per metric ton of
lead product, an afterburner, but no fuel for air preheating. Total energy
use for the 1 meter blast furnace is approximately 5.67 x 109 J/metric ton
Pb compared to 4.81 x 109 J/metric ton Pb for the SB furnace. Additional
energy is supplied in the SB furnace by the polypropylene and rubber battery
cases.
Production Data
The average SB furnace production rate during the test period (26 and
27 September) was approximately 70.5 metric tons per day. However, as can
be seen in Table 1, at least 4.86 metric tons of lead scrap (pipes, flashing,
drains, etc.) were included in the furnace feed during the test period. By
comparison, the production rate for a 1'meter blast furnace would be approxi-
mately 29.5 metric tons per day. The production rate (metric tons/day) per
square meter of furnace hearth cross-section is 17.6 for the SB furnace and
37.3 for the 1 meter blast furnace.
Table 7 presents the production data provided by the Bergs^e management
for the week of the test. Table 8 presents production data from a 91-day
campaign.
20
-------
TABLE 6. ENERGY CONSUMPTION DATA
Item
Coke
Oxygen
Air preheater
Afterburner
Agglomerators
Electricity
Vehicles
(2 front end
loaders, 1
fork lift)
Total
Consumption
units
kg
Nm3
liters (L)
liter s(L)
liter s(L)
joules (J)
liters (L)
Units per
metric ton
of lead
71.01
40.83
24.10
39.19
2.46
2.15
(estimate)
10 6 Joules
per unit
30.14
6.82 x 10~S
39.39
39.39
37.91
38.74
10 6 Joules
per metric
ton of lead
2140
0.0003
950
1540
93
0.42*
83
4806
*Based on 91-day average production of 75,769 kg/day
TABLE 7. REPORTED PRODUCTION DATA FOR THE WEEK OF SEPTEMBER 24, 1978
Furnace
output
Lead bullion
Flue dust
Slag
Matte
Weekly
production
482,300
21,500
271,000
95,200
Daily
average
68,900
3,071
38,714
13,600
Recorded data
25 Sept
81,675
2,320
41,800
14,686
26 Sept
79,200
2,900
37,688
1.3,241
27 Sept
61,875
3,480
38,716
13,601
Average
74,250
2,900
39,401
13,843
TABLE 8. REPORTED PRODUCTION DATA FOR A 91-DAY CAMPAIGN
(Weight in kilograms)
Furnace
output
Lead bullion
Flue dust
Slag
Matte
Weekly
production
6,895,000
614,300
4,195,400
1,474,000
Daily
average
75,769
6,750
46,103
16,198
21
-------
Furnace Operation
As mentioned earlier, the SB furnace operated steadily during the entire
test period. A number of parameters were recorded in order to show how the
furnace conditions varied during the test period. These are listed in Table
9.
The data listed in Table 9 are typical for the SB furnace operation.
The oxygen enrichment of the blast air is small, between 50 and 120 Nm3/hr.
However, the oxygen does help reduce the amount of blast air required, there-
by reducing the velocity of the gases rising through the furnace shaft. The
oxygen-enriched blast air pressure ranged from 1030 to 1180 mm H20. This is
slightly higher than the desired 800 to 1000 mm H20 operating pressure range
but did not cause any noticeable problems.
The major factor in reducing the quantity of process gas in the furnace
is the air preheater. By preheating the oxygen-enriched air to between 470
and 500°C in an external preheater, less coke is required in the furnace.
Thus a portion of the combustion products are eliminated along with the
combustion air required to burn the coke needed for air preheating.
The furnace top temperature is kept quite low relative to other blast
furnace operations. The process gas temperature ranged between 89 and 189°C
during the test period. The low top temperature prevents the battery case
material from igniting. Should the case material happen to ignite or begin
smoldering, additional material is charged to the top of the furnace and the
blast air is adjusted. The low top temperature also minimizes the amount; of
fuiae exiting in either the process or hygiene gas streams.
The process gases exited the furnace between 89 and 180°C during the
test period. The hydrocarbons in these gases are combusted in the oil-fired
afterburner. The gases exit the afterburner between 700 and 8008C. Fresh
air is then added through a small damper, cooling the gases to approximately
430°C. The gases cool further in the ductwork and are then mixed with the
cooler furnace hygiene air. The ratio of process gas to hygiene air is
approximately 1:2. The gases then enter the four baghouses at a temperature
below 130°C. If the temperature of these gases rises above 130°C, cold
ambient air is admitted via a small damper. This is done to protect the
felted polyester used as filter material. The gases cool in the baghouse
and exit the stack between 82 and 90°C.
HIGH VOLUME AIR MONITORING
One high volume (hi-vol) air sampler (GMWL model #2000H) was placed
under the easternmost baghouse near the two agglomeration furnaces (see
Figure 4). The hi-vol was approximately 80 meters from the smelter fence-
line. No ambient measurements were permitted at the fenceline because of the
close proximity of the rotary department (Building #3), the old smelter, and
the motorway which lies approximately 200 meters from the fenceline.
Two samples were collected during the test period. Table 10 presents the
test results.
22
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TABLE 9. OPERATING PARAMETERS RECORDED DURING
THE CHARACTERIZATION TESTS
Parameter
Oxygen flow
Oxygen/air pressure
Oxygen/air temperature
Blast air (In)
Water Jacket (In)
Water Jacket (out)
Furnace top (process)*
Afterburner (Inlet)
Afterburner (outlet)
Afterburner (outlet
after fresh air dilution)
Afterburner (outlet before
mix point)
Furnace top
hygiene air (avg.)
Bagbouse inlet temp.
(avg,)
Stack temperature
Stack gas flow
Units
Nm'/hr
mm H20
•c
HmVhr
°C
°C
°C
"C
•c
"C
•c
°C
ec
"C
HmVhr
9/25/78
1400
-
1050
474
3340
52.5
62
89/98
90
700
460
330
27
132
84
-
9/26/78
0830
58
1030
495
3720
47.5
64.5
101/180
150
-
430
290
27
110
85
120,000
Date/time
9/26/78
1500
114
1080
472
3240
48.5
59
93/100
100
750
415
290
25
104
82
120,000
9/27/78
0600
56
1030
495
3740
-
-
77/169
175
800
460
305
26
115
85
115,000
9/27/78
1500
97
1180
479
3340
48
57
143/105
135
800
435
320
26
117
90
120,000
^Temperatures at both process gas ducts exiting the furnace.
23
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TABLE 10. HI-VOL AREA SAMPLING RESULTS
Date
26 Sept 78
27 Sept 78
Sampling
period
(hr:min)
23:00
25:56
Total particulate
collected
(yg)
197,700
201,900
Total lead
collected
(yg)
24,500
41,600
Ambient air
concentration
(ug Pb/m3)
12
18
It is important to note that the sprinkler system failed during the second
test day. This caused the pavement to dry. This may have caused the in-
crease in total lead-in-air from 12 to 18 yg/m3 and caused the percentage
of lead in the collected particulate to rise from 12 percent on 26 September
to percent on 27 September. These datk highlight the importance of washdown
procedures in minimizing fugitive windblown dust in the smelter yard.
An extensive fenceline monitoring program was not conducted because of
the close proximity of the old smelter and a major motorway. It was felt
that fenceline monitoring data would have little significance because of
interference from these other sources.
STACK SAMPLING
Description of Sampling Locations
Stack sampling was performed from an instrument platform approximately
25 meters from the base of the stack. The stack is a double wall design
(see Figure 5). The inside diameter of the interior stack is 2.5 meters
and the inside diameter of the outside stack is 4.8jneters.
The instrument level was equipped with four access ports to the interior
stack, located at 90° intervals. Three ports were unavailable for use be-
cause plant instrumentation was installed in the ports. The one available
port was located in line with an instrument access hole through the outer
stack. This allowed the use of a probe of sufficient length to traverse one
entire diameter of the inner stack. The sampling location was approximately
ten diameters upstream and downstream of any flow disturbances. Velocity
measurements also indicate that the gas flow at the sampling level was
laminar. As a result, making a stack traverse across only one diameter
(rather than two at 90° angles) should not affect the validity of the
sampling results. Twelve traverse points were used during sampling. The
distances of the traverse points from the inside wall at the sampling port
are listed in Table .11.
24
-------
CONCRETE
SHELL
DECK
25 METERS
ABOVE GROUND
LIFTING AID
OUTSIDE STACK W
Figure 5. Stack cross-section.
02-3762-1
25
-------
TABLE 11. TRAVERSE POINTS MEASURED FROM THE
INSIDE WALL AT THE SAMPLING PORT1
Point Location (cm)
1
2
3
4
5
6
7
8
9
10
11
12
4.6
16.5
29.2
44.5
62.2
88.9
161.3
187.3
205.7
220.4
233.1
244.5
points are rounded to the nearest 0.6 cm.
EPA Method 5
The EPA Method 5 sampling train pictured in Figure 6 was used to deter-
mine the following:
Average stack temperature and velocity,
Lead particulate emissions, and
Total sulfur and chlorine emissions.
Stack Temperature/Velocity Determination—
The Method 5 sampling train was used to determine the average temperature
and velocity in the smelter stack on September 25, 1978. A traverse of only
one radius was possible because the other ports in the stack were in use.
26
-------
Probe Assembly
Particulate
Collection
STACK
PROBE
HEATED
AREA
THERMOMETER
REVERSE-TYPE
PITOT TUBE
PITOT MANOMETER
fllTEH
HOtOER
THERMOMETERS
Vapor Collection
IMPINOER TRAIN OPTIONAL. MAY BE REPIACEO
•T AN EQUIVALENT CONDENSER
THERMOMETER
ORIFICE
VACUUM
LINE
MAIN
VAIVI
DRV OA8 METER
Metering
Figure 6 EPA 5 sampling train.
Lead Particulate Stack Emissions—
Stack participates were collected on a glass fiber filter heated to
121°C (250°F) in a thermostated oven. Both the filter and probe were heated
during sampling. Table 12 presents the results of this experiment for both
test days. It is important to note that the average grain loadings for both
days were identical. This indicates that the baghouse was operating normally
and was allowing a constant amount of fine particulate to pass through with
the gas stream.
An analysis of the particulate matter collected on the filter was made
for lead and chlorine. Lead analyses were performed for these and all other
experiments using atomic absorption spectrophotometry. Chlorine analysis was
performed using a colorimetric determination. The emission rates were 56 and
46 grams of lead per hour on 9/26/78 and 9/27/78 repectively based on the
particulate collected on the filter. Table 13 summarizes the results of the
lead particulate emissions testing. No chlorine could be detected in the
particulate material.
27
-------
TABLE 12. EPA METHOD 5 RESULTS
Average velocity
determination
Date 26 Sept 78
Time 0910-0935
Sample duration 25 min
Sample volume at meter
Avg. meter temperature
Meter pressure 762 mm Hg
Avg. stack temperature 85°C
Stack pressure 761 mm Hg
Avg. gas velocity 9.50 m/s
Total gas flow 1.26 x 10s Nm3/hr
Moisture content of gas
(Volume %) 2.0
Gas molecular weight 28.2
Mass collected, filter
Mass collected, probe
Mass collected, total
Nozzle diameter
Nozzle area
Stack diameter
Stack area
Avg. sample velocity
at nozzle
Particulate concentration
Particulate mass rate by
area
Particulate mass rate by
concentration
Farticulate mass rate
Percent isokinetic
Particulate, chlorine, and sulfur
determination
26 Sept 78
1110-1210
1 hr
0.889 m3(0.802 Nm3)
31"C
762 mm Hg
898C
761 mm Hg
9.34 m/s
1.22 x 10s Nm3/hr
2.0
28.2
3.28 mg
26.08 mg
29.36 mg
0.617 cm
2.99 x 10~5 m2
2500 mm
4.91 m2
10.07 m/s
36.6 mg/Nm3
4.82 kg/hr
4.47 kg/hr
4.64 kg/hr
108%
27 Sept 78
0808-0944
1 hr 36 min
1.44 m3(1.31 Nm3)
31°C
764 mm Hg
87°C
764 mm Hg
9.08 m/s
1.19 x 10 5 Nm3/hr
2.4
28.1
4.72 mg
43.20 mg
47.92 mg
0.617 cm
2.99 x 10"5 m2
2500 mm
4.91 m2
10.20 m/s
36.6 mg/Nm3
4.92 kg/hr
4.36 kg/hr
4.64 kg/hr
112%
28
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TABLE 13. LEAD PARTICULATE EMISSIONS TEST RESULTS
Date
9/26/78
9/27/78
Gas voluM
sampled
(NmJ)
0.802
1.31
Stack gas
flow
(NmVhr)
1.22 x 10*
1.19 x 10s
Total partic-
ulate flow*
(kg/hr)
4.47
4.36
Pb particulate
collected t
(Vg)
365
505
Pb flow
rate
(g Pb/hr)
56
46
*Using measured concentration
t On Filter
These results indicate that the baghouse is extremely efficient in
removing lead particulate. There appears to be other material, perhaps a
condensing fume, which accounts for most (^99%) of the particulate collected.
Antimony pentachloride (SbCls) may constitute a portion of the particulate
collected. SbCl5 boils at 79°C and may be condensing between the baghouse
exit and the 25 meter level of the stack.
Sulfur and Chlorine Stack Emissions—
Sulfur and chlorine compounds were collected in a series of three im-
pingers which were placed behind the heated filter in the Method 5 sampling
train (see Figure 6). Two impingers in series containing 1% NaOH followed by
an impinger containing 6% H202 were used for the experiment. The filter used
to collect lead particulate was also analyzed for chlorine. A Dionex® ion
chromatograph was used for the sulfur determinations. A colorimetric deter-
mination using mercuric thiocyanate was used for the chlorine determinations.
The results of the gaseous sulfur and chlorine determinations are pre-
sented in Table 14. The sulfur emissions are fairly constant, 6.7 and 9.1 kg
S/hr. The chlorine emissions, however, varied by a factor of 4.4. This may
be due in part to a larger portion of flue dust or flue dust containing a
higher percentage of chlorine being recycled during the second day.
TABLE 14. GASEOUS SULFUR AND CHLORINE EMISSION TEST RESULTS
Date
9/26/78
9/27/78
Gaa volume
sampled
0.802
1.310
Stack gas
flow
(Nm'/hr)
1.22 x 10s
1.19 x 10s
•g
collected
44.1
100.0
Sulfur
gas cone.
-------
The sulfur emissions (as SOX) were checked on September 27 using
another sampling train containing a filter followed by two 6% H202 impingers.
The results of this test showed 41 ppm SOX in the gas stream, corresponding
to an emission rate of 7.0 kg S/hr. This is in good agreement with the
two values listed in Table 12.
The sources of the sulfur in the stack gas are the rubber battery cases,
battery acid or mud, coke, and afterburner and agglomeration furnace fuel
oil. The average SOX concentration in the stack includes the dilution effects
of the hygiene air, the afterburner and agglomeration furnace Combustion
products, and any additional cooling air.
The results of the chlorine determinations showed emission rates of 1.6
and 7.1 kg Cl per hour. These results are discussed in conjunction with the
results of the wet electrostatic precipitator tests in the following section.
Wet Electrostatic Precipitator (WEP)
The wet electrostatic precipitator (WEP) sampling train shown in Figure
7 was developed by Radian Corporation specifically for trace metal sampling.
An electrolyte is circulated through a round bottom flash and a vertical
glass cylinder by a peristaltic pump (see Figure 8). The walls of the
cylinder are wetted by the falling film of electrolyte. A thin platinum
wire is suspended in the center of the glass cylinder. A high voltage of
1.2 to 15 kV-DC causes a corona discharge at the center electrode. The gas
entering the WEP is first scrubbed and cooled in the round bottom flask.
PartiCulates and mist not retained here are electrically charged in the glass
cylinder, collected in the falling film and washed into the electrolyte
reservoir. This sampling device does not clog like a filter or a thimble,
and no analytical background corrections are necessary since no extraneous
material is introduced as is the case with filters. The probe consists of a
teflon nozzle and is teflon lined. Teflon tubing is used to connect the
probe with the WEP. All the lines are rinsed after sampling and combined in
the WEP. The WEP is followed by a train of nine impingers. The impingers
contained:
1) 20% HN03
2) 20% HN03
3) Dry
4) 10% NaOH
5) 10% NaOH
6) Dry
7) 61 E202
8) Dry
9) Silica gel (dessicant)
A pump and a dry gas meter complete the assembly. The WEP train was operated
isokinetically at a single point of average velocity in the stack.
30
-------
Teflon
Nozzle
Teflon lined Probe
Teflon
Tubli
Acid Implngers
fl)
X
Wet Electrostatic
Frecipitator
Caustic Implngers
llydroRonperoxi.de
Impinger
Ice Bath
Dry
ImpIngers
Silica C«l
laplngcr
Fine
Adjustment Valve
Coarse
Adjustment Valve
Pump
Figure 7. Schematic of the integral WEP sampling train.
31
-------
SAMPLE
OUTLET
PERISTALTIC
PUMP
HIGH VOLTAGE
POWER SUPPLY
PLATINUM
ELECTRODE
Falling Film of
Slectrolvte
SAMPLS
INLET
CIRCULATING
ELECTROLYTE
RESERVOIR
Figure 8. Wet electrostatic precipitator.
32
-------
Table 15 presents the results of the Method 5 WEP tests. All analyses
for lead, antimony, and arsenic in these and all other samples were performed
using atomic absorption spectrophotometry. The emission rates listed are
total emissions, including both gaseous and particulate species. It is im-
portant to note that the total lead emission rates listed in Table 15 for 26
September are 2.2 times higher than those listed in Table 13 for the solid
particulate in the Method 5 filter catch. This indicates that volatile lead
compounds may be escaping the baghouse in addition to the normal fine partic-
ulate matter. The material collected in the probe wash (see Table 12) may
account for part of the. difference in the WEP and Method 5 lead emission
values. However, the material collected in the probe wash appeared to be
organic in nature. Unfortunately, no analysis of the probe wash was made.
Consequently, an accurate comparison of the WEP and Method 5 results cannot
be made.
TABLE 15. TOTAL LEAD, ARSENIC, AND ANTIMONY EMISSION TEST RESULTS
Emission rates
26
27
Date
Sept 78
Sept 78
Volume of
gas sampled
(Nm3)
3.76
9.23
Total
gas flow
(Nm'/hr)
1.22 x 10s
1.19 x 10!
Lead
ng
collected
3800
1140
g Pb/hr
123
42
Arsenic
Ug
collected
15.3
35
g As/hr
0.50
1.29
Antimony
Pg
collected
16,500
14,100
g Sb/hr
535
519
Arsenic emissions are relatively low. This is to be expected because of
the small amount present in the feed materials.
The antimony emission rates of 535 and 519 grams per hour were unex-
pectedly high. These emissions can be attributed to the presence of chlorine.
It is believed that SbCl5 is the compound being emitted. SbCl5 boils at
79°C and may pass through the baghouse as a vapor. If no chlorine were
present, virtually no antimony emissions would be expected. Antimony oxide
Sb203, sublimes at 1550°C and would not be volatile at stack temperature.
Stack Emission Factors
In general, the measured emission rates for all species were quite low.
The stack emission factor ranges presented in Table 16 were calculated based
on a lead production rate of 70.5 metric tons of lead per day the Method 5
experiments for chlorine and sulfur, and the WEP experiment emission rates
for the metals. Of course, these results are for two days of normal opera-
tion. Different feed materials or operating conditions (e.g., only three
baghouses operating) could significantly alter these results.
33
-------
TABLE 16. STACK EMISSION FACTORS FOR THE SB BATTERY SMELTING FURNACE
Element Emission factor (g/metric ton Pb product)
Lead 14 to 42
Arsenic 0.17 to 0.44
Antimony 180
Sulfur (as S) 2300 to 3100
Chlorine 550 to 2400
MATERIAL FLOW
The determination of the flow of lead, antimony, arsenic, chlorine and
sulfur through the SB furnace was a key part of the characterization study.
Data gathered on the concentration of these elements in the smelter input
and output can help identify potential problems and advantages of the SB
furnace and the agglomeration furnaces.
Two days of sampling data were collected for the material flow deter-
mination. The furnace had been running steadily for more than a month
prior to the testing. The addition of polypropylene-case batteries to
the furnace charge was a change from normal operation, but no major change
in furnace emissions were either expected or observed.
Feed Characterization
An attempt was made to record the weight of all materials in each
charge during the test period. However, data on only five of the charges
were made available by the smelter management. As a result, an exact
material balance could not be completed for the test period.
Samples of each type of feed material were collected for analysis. The
samples taken are by no means homogeneous, integral samples. The feed
materials to most secondary lead smelters vary daily as different brands and
different type batteries are received for smelting. It was not possible to
collect an "average" or "homogeneous" sample representing two days of
smelting. On a monthly or yearly basis, a "representative" feed could be
determined.
As a result, grab samples of what appeared to be a typical feed sample
from the charge bedding floor were taken along with samples from each pile
of material used to prepare the charge. Table 17 presents the results of
the analyses of each of these samples.
34
-------
TABLE 17. AVERAGE FEED MATERIAL COMPOSITION
Pb Sb As S Cl
Material Date (Wt %) (ppm) (ppm) (Wt %) (ppm)
Feed composite
Battery plates t
(composite)
Return slag
Flue dusttt
Battery mud
Drosses
Coke
Rubber case
Polypropylene case
PVC separator
9/26 &
9/27
9/26
9/27
9/26
9/27
63.0
59.2
0.52
0.58
64.9
59.8
65.0
72.1
1.2%
7420
150
200
2295
1780
1:01%
4.26%
230
416
74
107
5
3
231
298
2.1
0.6
1.0
0.8
0.6
0.4
1.3
2.6
0.7
1.4
310
1200
4430
7100
26.0%
24.2%
5500
3600
370
370
51.5%
tNormal values range from 68 to 72 percent lead. The low value
measured here may be caused by sampling errors.
ttNormal chlorine content of flue dust reportedly ranges between
12 and 15 percent.
Product Samples
Samples of flue dust, slag, matte, and bullion were collected as they
were tapped from the furnaces. However, the matte and slag samples taken
directly from the furnace did not have a chance to settle completely. As a
result, additional samples were collected from the cooled slag pots after
the matte and slag were separated. The results of the product sample analy-
ses are presented in Table 18. Analyses for lead, antimony, and arsenic
were performed by atomic adsorption spectrophotometry. Sulfur analyses were
performed with a Leeko sulfur analyzer. Chlorine analyses were performed
by titration with AgNOa (the argentometric method).
35
-------
TABLE 18. PRODUCT STREAM ANALYSES
Material
Bullion
Matte
(from
Matte
(from
Slag
(from
Slag
(from
yard)
furnace)
yard)
furnace)
Flue dust
Date
9/26
9/27
9/27
9/26
9/27
9/26
9/26
9/27
9/27
9/26
9/27
Pb
(Wt
98.
99.
96.
4.
6.
10.
0.
0.
0.
64.
59,
%)
6
2
7
4
2
9
52
58
54
9
8
1
2
2
1
1
1
Sb
(ppm)
.96%
.24%
.10%
.22%
.28%
.68%
150
200
440
2295
1780
As
(ppm)
16
107
5
1685
1585
1685
5
3
99
5
3
S
(Wt %)
0.
0.
0.
19.
18.
10.
1.
0.
1.
0.
0.
19
11
16
62
82
98
04
79
56
61
36
Cl
(ppm)
268
275
210
5220
2350
2940
4430
7100
6930
26.0%
24.2%
Elemental Partitioning
A detailed material balance for the test period could not be completed
because weights of several furnace charges were not made available. However,
the results presented in Tables 4, 7, 17 and 18 do allow an estimate to be
made of how the elements present in the furnace are distributed in the
furnace products. The partitioning effect of the SB and agglomeration fur-
naces is shown in Table 19. Of course, chlorine was accumulating in the
furnace system during the test period. Chlorine is periodically removed
from the system by leaching the flue dust or by removing a batch of flue
dust for use in another smelting process. The numbers in Table 19 represent
the elemental partitioning several weeks after the last batch of flue dust
was removed.
TABLE 19. ELEMENTAL PARTITIONING IN THE SB SMELTING FURNACE
Feed Intermediate streams
material* Flue dust Slag
Element (kg/day) (% of feed material)
Product streams
Lead metal Matte Stack gas
(% of feed material)
Lead
Antimony
Arsenic
Sulfur
Chlorine
Total
79000
1500
29
2600
140
81814
2.52
0.43
0.04
0.59
580.2
0.27
0.44
0.53
13.28
159.6
87.68
98.49
10.38
0.14
17.83
0.90
1-1.15
75.66
98.00
36.81
0.0025
0.84
0.07
7.20
75.83
*Based on average feed for sampling period, 26 and 27, September, 1978, and
analytical results in Tables 14, 15, 17 and 18.
36
-------
SECTION 5
CONTROL TECHNOLOGY ASSESSMENT
DESCRIPTION OF EQUIPMENT AND CONTROLS
Section 2 of this report contains descriptive information concerning the
SB shaft furnace and controls. This section emphasizes the features of the
SB furnace and associated equipment which are important for the control of
employee exposures to lead and other workroom contaminants.
Receipt of Raw Materials
The containment and suppression of airborne contamination inherent in
handling feed materials is an integral feature in the design of this second-
ary lead smelting complex. Figure 9 presents an overview of the SB Furnace
Building and the Charge Storage and Preparation Building. Materials are
received by truck and are usually unloaded in the paved yard area. Here the
materials are separated and then transferred into the Charge Storage and
Preparation Building by large rubber-tired, diesel-fueled front-end loaders.
Industrial lift trucks are also utilized in the receipt (off loading) of
feed materials.
The paved yard area is kept wet by water sprinklers. Many of the
sprinkler heads are mounted at elevated locations on the sides of buidings.
The sprinklers activate automatically at preset intervals. The fixed
sprinklers are supplemented by mobile sprinkling trucks and wet sweeping
units. Water hoses are also used by employees to wet down surfaces and to
clean up mud, etc. Wet suppression of yard dust is feasible at this smelting
location since the climate is moderate with infrequent freezing weather.
Charge Storage and Preparation
The Charge Storage and Preparation Building (refer to Figure 9) is a
large concrete structure with concrete floors and multiple roll-up access
doors. To aid in dust suppression the floors of this building are periodi-
cally wetted using water hoses. Feed materials are stored in large bins
separated by concrete partitions. No processing of feed materials takes
place in this building. Those batteries which are received in whole form
are not decased and remain somewhat intact through the materials handling,
charge bedding and furnace charging operations. Other charge materials have
been processed by scrap dealers, etc. These materials (battery plates, etc.)
are mixed with other materials in the bedding procedure.
37
-------
Charge materials
storage —^
/-—"\
Charge bedding area
Charge storage and
preparation building
Air
monitoring
location
Recycle slag
pile
Feed materials
receiving area
(paved)
Charge
materials
storage
Roll-up doori
Furnace control room
SB furnaa
Ramp to second level
charging station
-Slag ladle
dumping area
o o
o
oo o o o o o o
oooo o o o o
OOOOOO OO
Slag ladle final
cooling area
SB furnace building
Baghouses
Afterburner
02-4447-01
Figure 9. Overview of SB furnace building and charge storage
and preparation building
38
-------
One rubber-tired, diesel-fueled front-end loader is routinely assigned
to this building and performs materials off-loading, storage in bins,
charge bedding and furnace charging. This front-end loader is equipped with
a filtered air supply to the operator's cab.
SB Furnace Charging Facilities
The charging of the SB furnace is performed on the second level of the
SB Furnace Building (refer to Figure 9). An indoor ramp connects this area
with the Charge Storage and Preparation Building. Charge materials are trans-
ported via front-end loader up this ramp from the charge bedding area and
deposited in the top of the furnace. This charging area is isolated from
the other work areas in the SB Furnace Building by a concrete floor.
The top of the SB furnace is provided with an exhaust hood which con-
tinually controls emissions from the furnace top. Figure 10 shows a sketch
of the SB furnace charging hood. This hood is part of the integrated venti-
lation control system which is schematically shown in Figure 11.
Performance of the ventilation system is monitored through use of sens-
ing devices (static pressure, temperature) which are connected to an opera-
tor's control panel located on the process control room on the ground level
of this building. Additionally, closed circuit TV cameras are trained on
the charging hood with TV monitors provided in the process control room.
This TV system can be used to monitor the performance of the charging hood
and also determine the need to add more material to the furnace.
Aside from the front-end loader operator, no employee routinely works
in the SB furnace charging area.
SB Furnace Operating Area
Most of the work involved in operating the SB furnace is performed in
the ground level work area of the SB Furnace Building. A sketch of this
work area is shown in Figure 12. As can be seen from the figure, the pro-
cess or operator's control room is located on this level together with the
lower portion of the SB furnace.
All of the activities normally performed at the base of a vertical shaft
smelting furnace are performed in this work area. Slag and finished hard
lead are tapped from the furnace into receiving ladles or crucibles. Emis-
sions from these operations are controlled by local exhaust ventilation hoods
which are part of the integrated ventilation system for the SB furnace
previously referred to in Figure 11.
39
-------
Collecting
plenum for
charging hood I
Flaps of conveyor
belt material
Area monitoring
location /6Y"*
Fold down lids
1 (in UP
I position)
Furnace hot flue
gas risers
Ducts from local exhaust
hoods on lower level
Area monitoring
location
Metal plates
Sidewall of
SB furnace
Figure 10. Furnace charging hood (Hood I)
02-4448-01
-------
Baghouse
No. 2
Baghouse
No. 1
Baghouse
No. 3
Baghouse
No. 4
02-4449-01
Afterburner
SB furnace
Figure 11. Key to local exhaust ventilation hoods
associated with SB furnace and agglom-
eration furnaces.
Agglomeration
furnaces
Hood
Description
A,B,C,D Slag tapping hood
E,F Secondary slag tapping
hood (fugitive emission
plenum)
G Finished metal tapping hood
H Finished metal ladle cooling
hood
I Charging hood
J,K Agglomeration furnace ladle hood
-------
f Roll-up doors -^
-d J a *-
Spiral
Stairs to
Charging
Level
Afterburner
Tuyere fugitive
emission hood Metal
/ tapping
\ *<£>."hooda
D
Shaft pi
_ ii
r urnace ^
• •y*g"a^^V" 'y'"1*1" •
&i*SS&
SZLa^^^fc^
r
V. Slae
Slag tapping
hoods
Process control
room
Roll-up door
OArea Air Monitoring
Station
o
Charge Storage and
Preparation Building
Noise Measurement
Location 02-4450-01
Figure 12. SB furnace ground level work area, SB furnace building.
42
-------
Figure 13 shows an overview of the local exhaust ventilation controls
associated with the base of the SB furnace. Hood F assists in the capture
of emission from slag tapping and from tuyere punching operations.
Slag and finished metal ladles are handled by forklift truck. The
floors in this operating area are frequently washed down through use of a
water hose. The four furnacemen and one furnace foreman do not wear res-
pirators while working in this area though they are accessible for emergencies
The process control room is located adjacent to this work area. It is
not equipped with special filtered ventilation and opens directly to the
process work area. Furnace operating personnel spend varying amounts of
time in the control room where consumption of beverages and smoking is
permitted.
Also located in this general work area is the oil-fired afterburner for
the SB furnace flue gas control system (refer to Figures 11 and 12). No con-
trols other than the process ventilation system are provided for this after-
burner. The final stages of the afterburner allow entry of dilution air for
cooling and pressure relief in the event of explosion. Agglomerated material
from the afterburner is collected in a slag ladle and emptied as necessary.
SB Furnace Integrated Ventilation System
Several references have already been made to the integrated ventilation
system for the SB furnace as depicted in Figure 11. The system is "inte-
grated" in that it handles both furnace flue gases and air collected by local
exhaust ventilation hoods.
The SB furnace uses preheated blast air which is injected into the
furnace through the tuyeres shown in the sketch in Figure 13. The flue gas
stream beyond the smelting zone in the furnace rises and is collected by a
header (doghouses) just below the charging level in the furnace. The flue
gases captured by these doghouses are ducted away from each side of the
furnace as shown in Figures 10 and 11. Each of the flue gas risers is
steeply angled to an apex where the two streams merge and flow down to the
afterburner located at ground level. The steep inclination of these ducts
reportedly makes them self cleaning, however, occasional cleaning may be
required.
After being processed through the afterburner, where some dilution air
enters, the flue gas stream is combined with the air drawn in through the
local exhaust ventilation hoods. The quantity of local exhaust air mixed
with the flue gas stream is regulated to keep the stream temperature below
130 °C (266 °F). Shortly thereafter this air stream is joined by the flue
stream from the flue dust agglomeration furnaces and then is processed
through baghouse filters. The baghouses are equipped with doors for cleaning
and bag replacement. Following the baghouses the exhaust stream is pulled
through large exhaust fans and then ducted to a tall stack.
43
-------
Flexible rubber
curtains
Furnace tuyeres
Slag tapping hood
swung away from
slag tap
(Hood C)
Slag ladle
Fugitive emission
plenum (secondary
slag tapping hood)
(Hood F)
Slag tap / I
and launder/ \
Metal plates
Finished metal
tapping hood
(Hood G)
Finished metal
ladle cooling
hood (Hood H)
Finished metal
ladle carrousel
Slag tapping hood
(Hood D)
02-4451-01
Figure 13. Overview of exhaust ventilation controls for the tapping of slag and finished metal.
-------
Flue Dust Handling
Flue dust collected in the baghouse filters is screw conveyed to the
agglomeration furnaces shown in Figure 11 and Plate 4. As stated earlier,
the flue gas emissions from these furnaces are collected by the integrated
ventilation system. Local exhaust ventilation in the form of a canopy hood
is provided over the slag ladle as shown in Figure 14.
As slag ladles are filled with agglomerated flue dust, they are removed
by forklift truck. The agglomerated material is stored inside to prevent it
from weathering and returning to a dust form.
DESCRIPTION OF EMISSION SOURCES AND POTENTIAL EXPOSURE
Materials Handling Emissions
At this smelter there are several situations where employees can be ex-
posed to contaminants emitted by materials handling. The following paragraphs
describe these situations, the employee interaction with the emission source
and the control of the source.
Receipt of materials—
Off loading and handling of raw materials can generate airborne contami-
nation. A varying number of employees may participate in raw material re-
ceiving at this smelter. Usually an equipment operator is involved who may
be the individual assigned to the Charge Storage and Preparation Building or
a person who routinely operates a front-end loader in the yard areas of the
plant. Occasionally, a general laborer or other person may assist in raw
material unloading.
As stated earlier the yard area is paved and kept wet. Prompt attention
to moving received materials to their respective inside storage areas is ex-
ercised. At the time this evaluation was conducted, scrap batteries were
also stored in piles outside the Charge Storage and Preparation Building.
Employees do wear respirators when handling dusty materials. One of the
front-end loaders is equipped with a filtered, air-supplied cab. Contamina-
tion tracked into the cabs of front-end loaders is periodically cleaned by
flushing the cabs with water sprayed from a hose. Hoses are also used to
flush the yard area with water to remove heavy mud accumulations. Addition-
ally, the yard is routinely swept with a large mechanical wet sweeper and
wetted using a sprinkler truck.
Storage and Handling of Charge Materials—
At this smelter charge materials are largely stored and handled inside.
Contamination generated by handling charge materials is largely confined to
the Charge Storage and Preparation Building. Stockpiles of materials within
the building are kept wet. One employee utilizes a front-end loader with a
filtered, air-supplied cab to move materials. Contamination tracked out of
this building by the front-end loader is controlled by the routine yard
clean-up procedures.
45
-------
Refractory lined
agglomeration furnace
exhaust flue
(30 cm, 12 in I.D.)
v
Swing-away section
of exhaust flue
Ladle hood
exhaust duct
Agglomeration
furnace
Point of air
flow measurement
^— Hood to ladle
T Gap 23 cm (9 in)
Slag ladle
/**\ (agglomerated
material)
Agglomerated
material
launder
|-»- 101 cm
(40 in)
(tf-
Ladle Hood Detail
Front Elevation - Agglomeration
Furnace and Ladle Hood
Figure 14. Agglomeration furnace and ladle hood (Hoods J and K).
02-4452-01
-------
this building by the front-end loader is controlled by the routine yard
clean-up procedures.
Slag Handling—
When slag ladles are filled from the SB furnace, they are allowed to
remain under the slag tapping hoods (refer to Figure 13) until the slag has
cooled sufficiently to form a thick crust. The ladles are then moved by
lift truck out of the operating area to a final cooling area shown in Figure
9. Here the ladles cool until the slag completely solidifies. Later a lift
truck dumps the slag out of the ladles in the paved yard area provided for
that purpose (refer to Figure 9). Still later, a front-end loader is used
to separate the slag from the matte which forms in the very bottom of the
slag ladle. This same front-end loader moves the slag and matte to separate
outdoor storage piles.
The procedures described above are directed at minimizing potential fume
emissions from molten slag and dust emissions from handling solidified slag.
Intimate employee contact with slag and matte materials is precluded by use
of mechanized materials handling equipment which does not create significant
granulation of slag materials. Wetted operating floors and yard areas help
prevent settled dust from becoming airborne. Some fume emission may be
occurring from the slag ladles at their final cooling station. No control
of this possible emission source is present. Employees do not routinely
work near the cooling slag ladle.
Finished Metal Handling—
When finished metal ladles are filled from the SB furnace, they are
allowed to remain under the finished metal ladle cooling hood (refer to
Figure 13) until the metal has substantially solidified. Allowing the
ladles to cool under the local exhaust ventilation rather than in the open
air helps to reduce the fume emissions during cooling and during any
handling of the ladle while the metal is still molten. The ladle is then
moved outside by forklift truck. Later, the metal ingot is elevated from
the ladle using a forklift truck as a hoist. The metal ingots are stock-
piled in the yard area until shipped or transported to refining operations.
Flue Dust Handling—
Flue dust which collects in the baghouse is screw conveyed to the
agglomeration furnaces. Screw conveyors can be a potential emission source
since they tend to leak near rotating shafts, bearings, access doors or lids,
etc. At this smelter, settleable particulate which escapes the screw con-
veyors will fall to a paved area below the baghouses and/or near the
agglomeration furnaces. Here the dust would be wetted and eventually flushed
into drains and sumps. Nonsettleable particulate which escapes from the
screw conveyors would contribute to general ambient contamination.
The agglomerated dust is slag-like in appearance. It is handled by
forklift truck while contained in slag ladles. It is not permitted to
weather outside which would result in its return to a dusty state. Employees
are not routinely assigned to work in areas near the agglomeration furnaces.
47
-------
Residues from Drains and Sumps—
The paved yard surfaces and floors inside operating areas are slopped to
drains and sumps. These water collection points are routinely cleaned to
remove deposits of mud. Given the wetted nature of the material dust genera-
tion is not an Immediate hazard. Splashes of particulate laden water, if al-
lowed to dry on work clothing, tools or work surfaces, could become a source
of airborne contamination.
The deposits or residues from these sumps are recycled to the smelting
process to recover their lead content. These materials are stored indoors
and kept wetted until charged to the smelting furnace.
Residues from Furnaces, Flues and Ductwork—
Routine maintenance at this smelter includes cleaning dusts and
residues from flues and ductwork. These periodic cleaning procedures create
opportunities for employee exposures. Employees do wear respirators during
these cleanup operations, some of which take place on a weekly basis.
When the entire SB furnace is shut down, the furnace cavity, flues,
ductwork, etc. are cleaned, inspected and repaired. These maintenance
activities can generate emissions and the handling of residues also involves
potential exposures. Employees are required to wear respirators during these
activities. Furnace shutdown periods have ranged in length from a few days
to a dozen or more days depending on the extent of maintenance required.
Charging Emissions
The depositing of material in the top of the furnace can potentially ex-
pose employees to (1) emissions from handling the charge material, and (2)
emissions from the furnace, such as flue gases which escape from the furnace
top. Both of these emissions would emanate from Hood I shown in Figure 10.
As stated earlier, only one employee spends any significant amount of
time in the furnace charging area. This employee operates a front-end loader
equipped with a cab supplied with filtered air.
Slag Tapping
Slag is tapped at each of four slag tap holes provided at the base of
the furnace. Each of these tap holes is equipped with a short launder. A
sketch showing the approximate location and configuration of the slag tap
holes is shown in Figure 13.
Slag is tapped from each of the four tap holes. Tapping involves re-
moving the tap hole plug and allowing the slag to flow down the launder
into a slag ladle. Unique tap hole plugs are used at this smelter which
consist of a tapered wooden plug surrounded by a refractory clay (refer to
Figure 15). This plug is placed in the tap hole and tamped tight. A
small amount of clay is added behind the plug. When the furnace is tapped
a bar is used to punch out the wooden core of the plug. Once the center
is clear, the hole can be easily enlarged by dislodging the surrounding
portion of the plug. This technique eliminates the need for drilling
48
-------
Wooden plug
• Metal bar
g
• Refractory clay
Slag Tap Hole Plug
Transparent window.
Tuyere cap rotates
for punching
Notch to permit
insertion of
punching bar
SB Furnace Tuyere
Figure 15. Details of slag tap hole plug and tuyere design.
02-4453-01
49
-------
out tap holes, using sledge hammers, etc. and insures that the tap hole
perimeter will remain intact and not emit excessive quantities of furnace
gases.
The slag tapping operation just described can be performed through an
access door in the hoods provided for slag tapping. A slag ladle is posi-
tioned under the tap hole. The slag tapping hood is moved into position over
the ladle and slag launder, and the tap hole plug is removed allowing the slag
to flow into the ladle. When the ladle is filled, a new plug is installed
by feeding it through the access door in the slag tapping hood (refer to
Figure 13). The ladle remains under the tapping hood until a substantial
crust forms.
The movable slag tapping hoods (Hood A, B, C, D) and the secondary slag
tapping hoods (Hoods E and F) have been provided to control emissions from
slag tapping (refer to Figure 13). Employees do not wear respirators during
slag tapping but do utilize face shields, gloves, etc. Slag taping is a
routine task for the furnacemen assigned to this work area. Slag tapping is
almost a continuous operation with one of the four taps flowing slag every
ten minutes.
Tuyere Punching
A sketch of the SB furnace tuyeres is shown in Figure 13 with a detail
of an individual tuyere shown in Figure 15. Routine tending of the furnace
involves examination of each tuyere through the transparent window shown
Figure 15. Periodically the tuyere cap is rotated and a steel bar is inserted
to punch out the air flow passage. The secondary slag tapping hoods (Hood
E and F) are provided to help control any emission from the tuyere punching
activity. Tuyere punching is a routine task for the furnacemen assigned to
this work area. Tuyeres are examined and punched as necessary at varying
intervals throughout the workshift.
Finished Metal Tapping
Finished metal is tapped at one end of the SB furnace as shown in Figure
13. The molten metal is an obvious source of contaminant emission. Exhaust
hoods have been provided for the finished metal tap hole, launder and re-
ceiving ladle (Hood G, Figure 13) and for the filled receiving ladle as it
cools (Hood H, Figure 13).
Tapping of the furnace can be performed with Hood 6 in position over the
tap hole, launder and ladle. One of the four furnacemen usually tends to
the finished metal tapping operation which is nearly continuous. As the
ladles are filled and rotated under the cooling hood (Hood H) the furnaceman
swings Hood H away for a few moments so he can insert steel lifting handles
into the molten finished metal. No control for employee exposure during this
handle insertion is provided.
50
-------
Afterburner Slag Port
The afterburner is equipped with a slag port which empties into a slag
ladle. No control is provided for fume emissions which may emanate from this
source. The afterburner slag tap port is located near the work area where
furnacemen prepare the slag tap hole plugs. There is a potential for some
exposure from this source. In comparison to other emission sources in this
general work area, the afterburner slag tapping port should be classed as a
low-order emission source.
Agglomeration Furnaces
The agglomeration furnaces are located outdoors in an area not fre-
quently visited by employees. The flue gas streams from these agglomeration
furnaces and emissions from the slag launder and ladle can contribute to am-
bient air contamination. The flue systems for these furnaces are cleaned at
weekly intervals. The swing away section of the flue directly above each
furnace was designed to facilitate this periodic cleaning (refer to Figure
14). A local exhaust ventilation hood is provided for the slag ladle and
launder. Possible emissions from these furnaces are not expected to signifi-
cantly contribute to employee exposures on a day-to-day basis.
Baghouse Bag Replacement
Manual replacement of bags during preventative maintenance or repair
work in the four baghouses creates the potential for employee exposure.
There is sufficient baghouse capacity at this smelter to allow shutdown
of one baghouse while the other three remain in operation. Workmen who
perform bag changes are required to wear respirators.
ENGINEERING CONTROL EVALUATION
Engineering control of employee exposure to lead and other con-
taminants at this smelter was evaluated using three basic sources of
information:
Engineering measurements and design considerations
Observations
Air sampling information
The sampling and analytical techniques used are NIOSH recommended physical
and chemical analytical methods document 173 (P&CAM 173).
51
-------
Raw Materials Handling
Engineering Measurements—
The engineering controls of interest to raw materials handling are:
(1) the use of sprinklers to suppress dust levels in yard areas, (2) the use
of a front-end loader with filtered air supply to handle raw materials, and
(3) the provision of a materials storage and preparation building to confine
and suppress airborne contamination associated with raw materials handling.
These controls were evaluated through observation and air sampling.
Observations—
Yard areas were observed to be kept moist by both fixed and mobile
sprinkling units. The floors of the Charge Storage and Preparation Building
remained wet in may areas, damp in others. Movement of the front-end
loader within this building did not create generation of visible air-
borne dust. The front-end loader operator remained inside the filtered
air cab except when reporting to the SB furnace control room and lavatory
area. The doors and windows of the fron-end loader cab were kept closed.
The roll-up doors to the Charge Storage and Preparation Building were opened
and closed as necessary to allow flow of materials. Several roll-up
doors were left open on the days evaluated.
Air Sampling—
To evaluate the effectiveness of the raw materials handling procedures
employed at this smelter, several air samples were gathered and analyzed.
The results of this air sampling are shown in Tables 20 and 21.
Air samples collected inside the cab of the front-end loader (Table 20,
Charge Preparation and Chargeman) indicate lead-in-air concentrations of 85
and 58 Ug/m3 on consecutive days. The initiation of sampling on the second
day was delayed until a flat tire on the front-end loader was repaired.
Two samples collected along the wall of the Charge Storage and Prepara-
tion Building (Table 21, Area No. 5, see also Figure 9) indicated lead-in-air
concentrations of 24 and 16 ug/m3. Additionally, air samples gathered at
either side of the charging hood (Table 21, Area Nos. 6 and 7, see also
Figure 10) indicated lead-in-air concentrations of (79 and 71) and (65 and
85) ug/m3, respectively. These samples reflect both the effectiveness of
dust control in the Charge Storage and Preparation Building and the effective-
ness of Hood I (Figure 10) in controlling emissions from charging and fugi-
tive flue gas emissions.
One air sample was gathered outside near an area of materials receiving
(Table 21, Area NO. 8; see also Figure 12). The sample indicated that the
lead-in-air concentration for the period evaluated was less than 8 ug/m3.
This sample result should not be interpreted as establishing an ambient back-
ground .
52
-------
TABLE 20. BREATHING ZONE, LEAD-IN-AIR CONCENTRATIONS
ASSOCIATED WITH SB FURNACE OPERATIONS*
Sampling interval
Lead-in-air exposure
Ug/m3 during the inter-
val sampled
9-26-78
Blast furnace
Foreman (JA)
Furnaceman (IM)
Furnaceman (LA)
Furnaceman (EJ)
Furnaceman (HP)
Charge prep.
& chargeman (DA)
6:21a - 10:57a
7:34a -
6:15a -
6:18a -
6:16a -
l:33p
l:37p
l:38p
l:38p
7:03a - l:40p
99
43
57
83
14
85
9-27-78
Blast furnace
Foreman (JA)
Furnaceman (MA)
Furnaceman (CO)
Furnaceman (MD)
Furnaceman (BB)
Charge prep.
& chargeman (DA)
6:08a - 12:23p
6:00a -
6:03a -
6:05a -
6:17a -
l:43p
l:50p
l:44p
l:49p
l:55p
110
35
110
38
79
=gge=™-^™.i»-....»e=8gBB8=g==™=g== i "
*Samples were collected on cellulose ester membrane filters with 0.8
pore size and were analyzed using atomic absorption spectrophotometry
(P & CAM 173).
53
-------
TABLE 21. WORK AREA LEAD-IN-AIR CONCENTRATIONS ASSOCIATED
WITH OPERATION OF THE SB FURNACE
Area no.
9-26-78
1
2
3
4
5
6
7
8
9-27-78
1 *>
2
3
4
5
6
7
8 J
a
Sampling location
Process control room
At wall near lead tapping
end of furnace
At wall near afterburner
At wall near tapping plug
preparation area
At side wall near center
of charge preparation
building
At working platform on
left side of charging
hood
A working platform on
right side of charging
hood
Near spiral stairs to
charging level
\
See location
descriptions
above
Sampling
6:24a -
6:30a -
6:43a -
6:35a -
6:56a -
6:48a -
6:50a -
—
6:00a -
6:12a -
6:33a -
6:22a -
6:36a -
6:07a -
6:07a -
6:41a -
interval
1
1
1
1
1
11
11
1
1
1
1
1
2
2
2
:50p
:50p
:50p
:51p
:55p
:30a
:30a
:55p
:45p
:58p
:58p
:55p
:00p
:00p
:00p
Lead-in-air expo-
sure ug/m3 during
the interval samp
38
23
<10
15
24
79
65
—
54
22
16
22
16
71
85
<8
*Samples were collected on cellulose ester membrane filters with 0.8y pore
size and analyzed by atomic absorption spectrophotometry (P & CAM 173).
to Figures 9, 10-and 12.
54
-------
SB Furnace Integrated Ventilation System
Engineering Measurements—
The evaluation of the integrated ventilation system (see Figure 11)
involved measurement of air flows at several strategic points. It was not
feasible to make measurements at every point of interest in the system.
Physical access was the primary constraint in this regard.
Figure 16 shows the points at which ventilation measurements were
made. Table 22 summarizes the hood entry coefficient measurements. Pres-
sure and temperature measurements were made at each point indicated in
Figure 16. However, these measurements and the resultant flow and velocity
calculations were considered proprietary and are not reported here. These
ventilation rates were consistent with those which would be specified using
appropriate design procedures as outlined in the ACGIH ventilation. Where
appropriate, hood entry coefficients were estimated and are presented in
Table 22. These measurements were made with all four baghouses in oper-
ation. Performance data concerning each of the many local exhaust hoods
was gathered and will be presented in succeeding sections.
Observations—
The integrated ventilation system was observed to be in good repair.
No serious dents or malformations of ductwork were found. The system is
constructed of heavy gauge steel and is provided with access openings at
strategic locations. The system is equipped with sensing devices (mainly
temperature indicators) which relay information to the control panel in the
process control room.
The SB furnace superintendent is thoroughly familiar with the design
and performance of the system and routinely makes velocity traverses in key
locations using a pitot tube and manometer. The process is equipped with
static pressure and temperature sensing devices which can be monitored from
the process control room. The baghouses are equipped with manometers so
that bag loading, broken bags, etc. can be detected by operating personnel.
Air Sampling—
The integrated ventilation system works as a unit to control lead-in-
air levels within the SB Furnace Building. Many of the emission sources
controlled by the system are physically close together. Employees who work
in this building spend varying amounts of time at different locations. For
these reasons the results of air sampling performed during this evaluation
(breathing zone and work area) are more indicative of total system perfor-
mance and work practices than of performance of individual hoods, etc.
During the days evaluated, the roll-up doors to the ground level oper-
ating area of the SB Furnace Building remained open much of the time. Two
consecutive day shifts were monitored. A furnaceman crew change occurred
between the first and second day of evaluation so possible differences in
work habits are reflected in the data gathered.
55
-------
Baghouse
No. 3
Baghouse
No. 2
Baghouse
No. 4
Figure 16. Key to ventilation system test points.
02-4454-01
-------
TABLE 22.
SUMMARY OF HOOD ENTRY COEFFICIENTS IN SB FURNACE
AND AGGLOMERATION FURNACES VENTILATION SYSTEMS*
0.58
T2
0.56
T3
Tl,
T5
T6
T7
T8
0.57
Tio
0.05
TH**
0.76
*Air flow measurements were made using a pitot tube and inclined manometer;
in-duct velocities, flow rates, temperatures, and pressure data were con-
sidered proprietary and are not reported here.
**Calculated results
***
Cc
, where SPh = hood static pressure
57
-------
Tables 20 and 21 contain the lead-in-air sampling data. Breathing zone
measurements ranged from 14 to 110 yg/m3 and average 67 yg/m3 for persons
working in the SB furnace operating area. Work area lead-in-air concentra-
tions measured in the SB furnace operating areas ranged from less than 10 to
54 yg/m3 and averaged 25 yg/m3. It is interesting to note that the highest
work area lead-in-air concentration in the SB furnace operating area was
found in the process control room.
A few work area air samples were also collected and analyzed for arsenic.
The results of this sampling are contained in Table 23. No result greater
than 0.32 yg/m3 was found.
SB Furnace Charging Hood (Hood I)
Engineering Measurements—
A sketch of Hood I is shown in Figure 10. Figure 17 contains dimensional
information and air flow measurements. The hood provides a minimum of 0.76
m/s (150 fpm) across its face. An Alnor® Velometer, Jr. was used to measure
face velocity.
Observations—
Smoke rising from the charged material inside the hood was observed to
remain within the hood. Smoke generated at the edge of the hood and at
locations in front of the hood face (using ventilation smoke tubes) indicated
air movement into the hood at all positions.
Charging the furnace via the front-end loader was observed and no visible
emissions were seen to escape from the hood.
Air Sampling—
Air samples were collected at the work platforms on either side of the
charging hood (refer to Figure 10). The results of these measurements are
contained in Table 21 and are only partially indicative of the hood's per-
formance. These sampling results reflected general workroom contami-
nant levels in the charging work area, as well as, possible contamination
escaping from the hood.
Slag Tapping Hoods (Hoods A, B, C, D)
Engineering Measurements—
The SB furnace is equipped with four slag tapping hoods (Hoods A, B,
C, D). These hoods are ducted into the integrated ventilation system as
shown in Figure 11. These hoods work together with other exhaust ventilation
as shown in Figure 13. The hoods are essentially identical in design. All
are constructed from heavy metal, employ external duct fins or webs for
structural support and are made movable through use of high quality swivel
bearings. Figure 18 provides dimensional information concerning these hoods
and air flow data. An AlnorR Velometer was used to evaluate air flows
associated with these hoods.
58
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TABLE 23. WORK AREA ARSENIC-IN-AIR CONCENTRATIONS
ASSOCIATED WITH OPERATION OF SB FURNACE*
Area no.
Sampling location'
Arsenic concentra-
tion yg/m3 during
Sampling interval the interval
(9/27/78) sampled.
At wall near lead tapping
end of furnace
6:12a - l:45p
0.32
At wall near afterburner
6:22a - 12:22p
0.15
At working platform on
left side of charging
hood
6:17a - 2:00p
0.11
*Samples were collected on a cellulose ester membrane filter with 0.8 y
pore size and were analyzed using the arsenic/borohydride method.
(Pierce, et al; Applied Spectroscopy, (30), 1976)
8Refer to Figures 2 and 4.
59
-------
Flaps of conveyor
belt material
Face Velocity
Measurements
/
A
B
I
C
D
E
F
G
H
1
J
K
L
M
N
0
P
Q
R
S
T
U
V
W
5.48
m (18
ft)
Ft
A
B
C
D
E
F
G
H
I
J
K
L
M
N
0
P
Q
R
S
T
U
V
W
m/s
1.0
1.0
1.5
1.5
1.3
0.89
0.89
0.89
0.89
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.76
0.76
1.0
1.0
1.0
1.0
0.76
fpm
200
200
300
300
250
175
175
175
175
200
200
200
200
200
200
200
150
150
200
200
200
200
150
Figure 17. Face velocity measurements
(Hood I).
- furnace charging hood
02-4455-01
-------
Swivel bearing
Inside diameter
30 cm (12 In)
Duct fins for structural
support of hood
Air flow measurement
cross section
Hood extention to cover
slag tap hole and launder
Hood B
Air flow measurements
at indicated cross section
A - 0.0707 m2(.785 ft2)
Hood Entry Coefficient
Ce s 0.57
102 cm (40 in)
(diameter)
Swivel bearing
Access opening for
slag tapping
Roller support for
tapping bar
02-4456-01
Figure 18. Side elevation - slag tapping hoods (Hoods A,B,C,D).
-------
Figure 19 illustrates the relationship of the slag hoods to the slag
ladles. Air velocities measured at the access opening and along the gap
between the hood and ladle are indicated. As can be seen from the data,
these hoods afford vigorous face velocities.
Observations—
The slag tapping hoods were used by all furnacemen. As stated earlier,
the slag tap holes at the side of the SB furnace can be opened and closed
through use of implements inserted through the access opening in the slag
tapping hood. Several tap hole opening and closing operations were observed.
The hoods appeared to capture virtually all smoke and fume emanating from
the tap hole, slag launder and slag ladle. Occasionally a heavy spark of
molten material would escape through the front access opening.
Uniform flow into the slag hoods at all sides was confirmed through
observation of smoke generated from ventilation smoke tubes.
Employees performing slag tapping operations always remained at least
1 to 2 meters (3 to 6 feet) from the hoods during tapping. Opening, closing
and tending of the tap hole was accomplished through use of long metal rods
and other long handled implements.
After slag ladles were filled, they were allowed to remain under the
slag tapping hoods until a substantial crust had formed on the top of the
molten slag. During the two days evaluated, no accidental spills of slag
occurred. Furnacemen carefully maneuvered slag ladles using a forklift
truck. In some instances ladles were removed with the slag tapping hood
still in position over the tap hole and launder.
Secondary Slag Tapping Hoods (Hoods E and F)
Engineering Measurements—
The SB furnace is equipped with two secondary slag tapping hoods (Hoods
E and F) located along either side of the furnace. These hoods are ducted
into the integrated ventilation system as shown in Figure 11. These hoods
work together with other exhaust ventilation as shown in Figure 13.
Figure 20 provides additional information concerning these hooods. Data
concerning air flow through the exhaust plenum is included in Table 22 (Test
Point 12). These hoods are intended to capture emissions from
slag tapping and tuyere punching operations.
Observations—
Refer to Figure 20 for observations concerning hood performance.
Finished Metal Tapping Hood (Hood G)
Engineering Measurements—
Hood G is provided to control emissions from the finished metal tap hole,
launder and receiving ladle. Hood G is ducted into the integrated ventila-
tion system as shown in Figure 11. This hood works together with other ex-
haust ventilation as shown in Figure 13.
62
-------
U>
Face Velocity Measurements
at Access Opening
Hood B
Ft m/a fpm
1
2
3
4
5
6
7
8
9
2.4
2.2
2.2
1.9
1.8
1.8
1.8
1.8
1.8
480
430
430
380
350
350
350
350
350
Face velocity at gap
1.8 - 3.0 m/s
(350-600 fpm)
Hood
m/s
2.8
2.8
1.9
2.2
2.2
1.5
2.8
2.9
2.8
D
fpm
550
550
380
430
440
300
400
580
400
Slag ladle
Access opening
Gap
2 to 6 cm
(1 to 2.5 in)
Slots for tongs from
lift truck to move
slag ladle
02-4457-01
Figure 19. Front elevation - slag tapping ladle (Hoods A,B,C,D).
-------
Fugitive emission
plenum for secondary
slag tapping hood
(Hood E)
Inlets to
/ plenum
Smelting
furnace
Flexible
Rubber
Curtains
Concrete
column
Air Flow Measurements
Hood Entry Coefficient
Ce = 0.56
• Air velocities near tuyeres and
flexible rubber curtains were less
than 0.13 ra/s (25 fpro)
Smoke generated inside the hood was
observed to flow upward toward the
exhaust plenum inlets
• Smoke generated near the flexible
rubber curtains indicated low order
turbulence on back side of curtains
Note: Details of slag ladles, slag
tapping hoods, etc. are exluded from
this figure for simplicity
02-4458-01
Figure 20. Secondary slag tapping hoods (Hoods E and F).
-------
Hood G, like the slag tapping hoods, is constructed of heavy gauge
metal and employs external duct fins or webs for structural support of the
hood (refer to Figure 21). The hood is made movable through use of swivel
bearings. The bottom edge of the hood is equipped with hanging chains to
help control any splashing of molten metal, increase face velocity at the
gap between the hood and ladle and facilitate rotation of ladles under the
hood.
The access opening at the hood is used to observe and allow access to
the finished metal tap hole.
Figure 21 provides dimensional information for Hood G. Face velocity
measurements made at the access opening and near the hanging chains associ-
ated with the hood are indicated. An Alnor® Velometer was used to make these
measurements. As can be seen from the data, Hood G provides vigorous air
flow into the hood.
Figure 21 also contains calculated hood performance data. These data
and others are also presented in Table 22 (Test Point 11). Flow into this
hood was determined by taking the difference in flows measured at Test Points
6 and 9 shown in Figure 16.
Observations—
Hood G appeared to capture all of the smoke and fumes emanating from
the finished metal tap hole, launder and receiving ladle. During the two
days evaluated, Hood G was not moved from its position over the tap hole and
launder. Smoke generated from ventilation smoke tubes at the edges of the
hood indicated flow into the hood at all sides.
Occasionally a spark of molten metal was observed to escape from the
front access opening. This usually occurred when the tap hole and launder
were being cleaned through use of a long metal rod inserted through the
access door.
Finished Metal Ladle Cooling Hood (Hood H)
Engineering Measurements—
Hood H is provided to control emissions from molten metal contained in
a receiving ladle which has recently been filled. Hood H is ducted into the
integrated ventilation system as shown in Figure 11. This hood works to-
gether with other exhaust ventilation as shown in Figure 13. Hood H like
Hoods A, B, C, D, and G is constructed of heavy gauge metal and employs ex-
ternal duct fins or webs for structural support of the hood (refef to Figure
22). The hood is made movable through use of swivel bearings. The bottom
edge of the hood is equipped with hanging chains to help improve face veloci-
ty and facilitate rotation of ladles under this hood.
As indicated in Figure 22, Hood H is a slotted hood. The slot evenly
distributes the capture zone around the perimeter of the ladle. Air flow
information gathered using a pitot tube and inclined manometer at Test Point
T9 (see Figures 16 and 22) is presented in Table 22 and in Figure 22.
65
-------
Air flow measurements
Face velocity at gap
Near chains 1.5 m/s (300 fpm)
At front of hood in space with
no chains 2.5 m/s (500 fpm)
Face velocity at access opening
Swivel bearing
Duct fins for structural
support of hood
Swivel bearing
A
B
C E
D F
(•« — 40.6 cm — v
t
22.9 cm
(9 in)
10
(16 in)
Pt
A
B
C
D
E
F
m/s
2.3
2.4
2.0
1.7
1.8
1.3
fpm
450
480
400
340
350
250
71 cm
•
(28 in)
10 cm (4 in) gap -
81 cm (32 in)—
Inside diameter
31.5 cm (12.4 in)
Access opening for
finished metal tapping
Hood lower diam.
142 cm (56 in)
Chains
Finished metal ladle
(top diameter 127 cm
50 in)
Finished metal
ladle carrousel
02-4459-01
Figure 21. Front elevation of finished metal tapping hood (Hood G).
-------
Swivel bearing
Duct fins for
structural support
of hood
Inside diameter
19.7 cm (7.75 in)
15.2 cm (6 in)
hood depth
10 cm (4 in) gap'
Finished metal
ladle carrousel
Damper
Expansion Takeoff
Flange
Finished
< metal ladle
Hood Entry Coefficient
Ce - 0.65
Air flow measurement
V - = 19.3 m/s (3800 fpm)
slot
Hood radius
71 cm (28 in)
12 mm (5/16 in)
slot
Radius to slot
56 cm (22 in)
Side elevation of finished
metal ladle cooling hood
Detail of slot design
inside head
02-4460-01
Figure 22. Finished metal ladle cooling hood (Hood H).
-------
Additionally, slot velocities and face velocities measured with an Alnor®
Velometer are included in Figure 22.
Observations—
Ventilation smoke tubes were used to generate visible smoke at the edge
of this hood. The smoke was observed to flow into the hood at all locations
around its circumference.
Hood H was swung away from over the cooling ladle to allow insertion of
handles into the molten metal. This operation required only a few moments to
complete but did require the furnaceman to lean over the ladle containing
cooling molten metal. The employee did not wear a respirator when perform-
ing this task which occurred a few times each shift.
Agglomeration Furnace Ladle Hood (Hoods J and K)
Engineering Measurements—
Hoods J and K are ducted into the integrated exhaust ventilation system
as shown in Figure 11. Dimensional information and proximity to the agglom-
eration furnaces is shown in Figure 14. Also included in Figure 14 is an
estimate of the air flow through these hoods.
Face velocity measurements were precluded by significant ambient air
currents present on the days evaluated. Hi-vol area sampling near the ag-
glomeration furnaces detected 12 and 18 yg Pb/m3 on the test days (see
Table 10, Section 4).
Observations—
The gap between the slag ladle and hood is quite large (refer to Figure
14). Smoke generated under and near the hood using ventilation smoke tubes
was not effectively captured by the hood. Ambient air currents overpowered
the influence of the hood and allowed generated smoke to escape.
OTHER INDUSTRIAL HYGIENE CONSIDERATIONS
Employee Work Schedules
The SB furnace operates continuously. Five teams of employees man
three shifts of work. Each employee works an average of 36 hours per week.
Personal Protective Equipment
Clean trousers, shirts and work jackets are furnished each week to
employees. Employees provide and wash their own underwear. Use of gloves,
safety helmets and safety glasses is optional. Employees wear safety-toe
footwear and utilize faceshields during slag tapping. Respirators are re-
quired to be worn during furnace clean-up or repair, baghouse maintenance,
and during routine flue and duct cleaning. The charge preparation operator
does not normally wear a respirator. He may elect to wear one during hand-
ling of particularly dusty materials which are occasionally received by the
smelter.
68
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Employee Hygiene
Employees are instructed to shower at the conclusion of each shift and
to wash before eating. Locker room, shower and lunchroom facilties pro-
vided at this smelter are not elaborate. Employees are permitted to smoke
and consume beverages in the SB furnace process control room. It was
observed that employees did not wash their hands each time they used
smoking materials or consumed beverages in this area.
Biological Monitoring
Urine specimen collection and analysis is not performed. Blood samples
are obtained from operating employees each month and from other employees on
a quarterly basis. The results of blood lead monitoring are reported to
employees and the employees have access to all of their blood lead analysis
results. The employee is informed that his result is acceptable (less than
70 ug Pb/lOOg whole blood), marginal (71-90 ug Pb/lOOg whole blood) or
unacceptable (90+ ug Pb/lOOg whole blood). The employee is also informed
whether the result shows a strong increase, increase, no change, decrease
or strong decrease in blood lead level since the last test. Exhibit A con-
tains the blood lead monitoring data for employees assigned to the SB fur-
nace which were made available to this evaluation.
Workplace Air Monitoring
Reportedly, many workplace lead-in-air measurements were made shortly
after the SB furnace was made operational. Three to four months prior to
this evaluation smelter personnel made their most recent breathing zone and
work area measurements. The results of these measurements were not requested
for inclusion in this evaluation.
Noise Level Measurements
A sound level survey was made of the operations associated with the SB
furnace. The results of this survey are shown in Table 24. As can be seen
from data, no serious noise sources were discovered.
CONTROL CRITIQUE
The engineering and work practice controls of employee exposure at this
smelter are exemplary. The effectiveness of this system of controls is evi-
denced by the control of employee exposures to lead in all work activities
associated with the SB furnace to approximately 100 ug/m or less.
In general, the local exhaust ventilation systems provided for the SB
furnace are well designed and maintained. They provide good enclosure of
emission sources, vigorous hood face and duct transport vel 'cities,^ access
i
=S5.
from other 5 furnace work areas provides obvious benefit In confining
69
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TABLE 24. RESULTS OF NOISE MEASUREMENTS MADE IN
ASSOCIATION WITH SB FURNACE OPERATIONS
Location no.
1*
2*
3*
Description of measurement
location and/or operation
2 meters from burner end of
afterburner
2.5 meters from side of
afterburner
Slag tapping location, after-
Noise
type1
S/I
S
s
S
Sound '
Expo s ure2 level 3
C/I
I
I
I
dBA
78-80
81-83
81-82
dBC
88-90
91-94
87-88
4*
5*
6*
7*
8
10
11
burner side of furnace, metal
tapping end of furnace
Near finished metal ladles S
Slag tapping location, control S
room side of furnace
1 meter from afterburner end S
of furnace
Process control room S
Charging level, right side S
of charging hood
Charging level, near combustion S
air fan for afterburner
Inside cab of charge prepara- S
tion front-end loader
I
I
I
I
75
74-75
55-57
79-81
92-94
80-88
84-85
84-86
77-78 89-90
69-71
84-87
94-96
88-98
*Refer to Figure 1 for location of sound level measurement
1JJoise type: S = steady, I = Impulse or impact
2Exposure: C = continuous, I » intermittent
3Sound level: Measured in decibles on the A and C weighting networks of a
type S2A sound level meter
70
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contamination generated by these operations to the Charge Storage and
Preparation Building. The low lead-in-air concentrations found in this build-
ing must be at least in part attributable to the handling of agglomerated flue
dust rather than bulk quantities of untreated flue dust.
Yard sprinling and washdown procedures appear to minimize entrainment of
dust into the air, tracking of muddy materials into other work areas, and
splashing of mud on employee clothing and plant equipment.
Washdown procedures employed in the SB furnace operating area did main-
tain floors in dust free and clean conditions. Washdown operations were
timed so that slag was tapped into ladles and then floors were washed. By
the time slag was to be tapped again the floor covered by metal plates at
the slag tapping station was essentially dry. According to operating per-
sonnel, the presence of wetted floors near molten metal and slag handling
has not resulted in increased hazard when molten metal or slag spills have
occurred.
A few situations were discovered which could be improved. They are:
• The SB furnace process control room was found to be contaminated
with lead (38 to 54 yg/m3) . Since employees are permitted to
smoke and consume beverages in this area, it is recommended that
improved ventilation and housekeeping be provided to reduce lead
contamination. It is unknown to what extent the contamination
of this control room together with smoking and beverage consump-
tion and other hygiene practices contribute to employee lead ab-
sorption as evidenced by reported blood lead levels.
Ventilation of the control room could be engineered to bring in
outside air through filters and maintain the control at a slight
positive pressure with regard to the SB furnace operating floor.
In any future installations of this type, consideration should be
given to enlarging the control room and arranging control panels
so that the base of the SB furnace could be viewed through windows
in the control room wall. This would reduce traffic in
and out of the control room when simple observations or hand sig-
nals to employees are required.
The insertion of metal handles into molten finished metal at the
finished metal ladle cooling station currently creates some uncon-
trolled exposure to the employee performing this operation. Ex-
posure occurs when the employee must lean over the ladle to insert
the handles and hold them until frozen in place. Possibly a set of
tongs or other such tool could be used to reach over the ladle and
insert the handles preventing the employee from being directly ex-
posed.
Limitations of the study did not permit careful evaluation of the
effectiveness of the air filtration system provided for the cab of
one front-end loader. If this filtration system is indeed
71
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effective, its installation on all similar yard equipment
used at this smelter should be considered.
The local exhaust hoods provided for the slag ladles at the
agglomeration furnaces could be made more effective by reducing
the gap between the ladle and hood and also reducing the velocity
of cross drafts caused by wind. It is suggested that a concrete
pad or other substantial stand be provided to elevate ladles
closer to the hoods. The bottom of the hood could be fitted with
hanging chains to help break up cross draft air movement.
72
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SECTION 6
OTHER PROCESSES AND CONTROLS
In addition to the SB furnace and associated equipment, a variety of
other smelting processes are operated at the Paul Bergs^e and Sons A/S
Glostrup, Denmark facilities. Two of these processes: (1) rotary furnace
smelting, and (2) pot induction furnace smelting were evaluated during
this study. Each of these processes received relatively less attention
than the SB furnace. The primary aim of the evaluations of these processes
was to describe control equipment which may be readily adaptable to similar
processes in the United States.
ROTARY FURNACE SMELTING
Description of Equipment and Controls
Rotary furnace smelting operations are conducted in separate facilities.
Figure 23 shows a large building which is divided into two major sections.
One part of the building is devoted to furnace operations while the other
part contains charge storage and preparation functions.
Receipt of Raw Materials—
A variety of raw materials (slags, drosses, etc.) are received for
smelting in the rotary furnaces. These materials are unloaded from trucks
and stored in the segregated bins in the Charge Storage and Preparation Build-
ing shown in Figures 4 and 23. The yard unloading area is sprinkled and
washed down in similar fashion to that described for the SB furnace facili-
ties. Materials are handled by a variety of front-end loaders.
Charge Storage and Preparation—
The Charge Storage and Preparation Building associated with the rotary
furnaces (refer to Figure 23) is a concrete structure provided with a large
roll-up, materials delivery door, twelve bins for segregating raw materials,
and another roll-up door which communicates with the rotary furnace operat-
ing area. This building is equipped with an automatic sprinkling system
which periodically wets floors and dampens piles of raw materials. Several
bins containing bagged, relatively non-toxic materials are not sprinkled.
No mechanical ventilation is provided for this building.
73
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Charge
material
storage
bins
Charging and
tapping hood
Charge storage and
preparation building
. Refractory
/ storage
«___J
Brick flue
Welding
shop
^V (Stockpiled *
J 1 |finished metalj
' \ "
door and
charge container
resting deck
Rotary
furnace
building
Locker
room
Control
room
(D
i©
I
i
furnace
oooooooo
Slag crucibles (cooling)
Refractory storage
and preparation
crucible '
storage QOO
^
1 ' Lllir
Roll-up
Door
Roll-up door
OArea air monitoring
location
Scale:
O Location of noise
measurement
6 meters
Figure 23. Rotary furnace smelting and charge storage preparation building.
02-4461-01
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Rotary -furnace Charging Equipment—
Charge materials for the rotary furnace are placed in specially
designed charge containers which rest on a low platform behind the roll-up
door between the furnace operating and charge preparation section of the
building. Figure 23 shows the location of this charge container resting
platform. Figure 24 shows a close up of the charge resting platform and a
detail of an individual charge container.
Each rotary furnace is equipped with a round charging door in the
center of the front end of the furnace (refer to Figure 25). The lift truck
picks up the charge container from one end, inserts it into the furnace,
and then rotates the container to dump the charge material. Rotation is
accomplished through use of a rotating lift head on the lift truck.
After dumping, each container is rotated back to its upright orientation,
removed from the furnace and replaced on the charge container resting deck.
When all containers have been emptied into the furnace the roll-up door at
the resting deck is closed.
An exhaust hood is provided at the front of the furnace to capture emis-
sions from the furnace during charging. A sketch of this hood is shown in
Figure 25. Exhaust draft to this hood is controlled by a damper located
directly behind the hood.
Rotary Furnace Operating Controls—
The two rotary furnaces studied are tangentially fired from the rear.
Hot combustion gases enter the furnace body, circulate to the front of the
furnace and then are exhausted through the brick flue (Refer to Figure 23
and 25) . The furnaces are of steel shell construction with refractory
lining. They rotate 360° and the rotation can be reversed.
Figure 25 shows the exhaust ventilation controls for the rotary furnaces.
Hot flue gases are exhausted through the brick flue. The gap between the
furnace body and the brick flue is enclosed and exhaust ventilated. An
arched hood is provided over the charging/tapping end of the furnace. Exhaust
draft to this hood is controlled by an electrically operated damper. The
damper is opened during charging and tapping. The two furnaces are operated
on staggered 10 hour cycles which allows the exhaust draft to be directed
from one furnace to the other during alternating charging and tapping
operations. The retractable portions of the arched hood open to allow an
overhead crane to pickup filled ladles and replace empty ladles.
Each furnace is provided with a ladle cooling hood. After tapping ladles
filled with finished metal are set beside the furnace at a location where
a ladle can be swung over them to capture emissions during cooling. (Refer
to Figures 23 and 25.
75
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Concrete floor
and wall
Roll-up door
Resting deck
Detail of charge container
02-4462-01
Figure 24. Close-up of charge container resting deck, roll-up door, and detail of charge container.
-------
Electrically
Operated
Damper
Retractable
arch hood
enclosures
Finished
metal ladle
Brick flue
Hood enclosing
furnace to flue
connection
Wide slot exhaust
pickups
168 cm (5 ft 6 in)
Figure 25. Rotary furnace charging and tapping controls.
02-4463-01
77
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No mechanical dilution or makeup air ventilation is supplied to the
rotary furnace operating area. Natural ventilation is facilitated by open-
ings in the roof and along each of the side walls of the building. Air also
enters through the large roll-up doors which are frequently open.
Air drawn into the rotary furnace local exhaust ventilation hoods and
into the hot gas flue is combined and passed through a baghouse before
being release to the ambient environment. Flue dust is collected in fabric
cubical containers and recycled to the rotary furnaces. At the time this
evaluation was performed, flue dust from the rotary furnaces was not being
agglomerated.
The floors of the rotary furnace operating area are routinely flushed
with water. The water drains into central sumps which are periodically
cleaned to remove sludge or mud.
Employees do not routinely wear respirators while working in the rotary
furnace operating area. Respirators are worn in the rotary furnace Charge
Storage and Preparation Building, when handling flue dust and when working
with storage piles in the yard area surrounding the rotary furnace building.
A process control room is provided in the rotary furnace operating area.
This room contains process control panels and is also used as a rest area
where employees are permitted to smoke and consume beverages.
Description of Emission Sources and Potential Exposures
Materials Handling Emissions—
In this portion of the smelter there are several situations where
employees can be exposed to contaminants emitted by materials handling. The
following paragraphs describe these situations, the employee interaction
with the emission source and the control of the source.
Raw Materials Handling—Off loading and handling of raw materials can involve
generation of airborne contamination. In this portion of the smelter flue
dust is handled in unagglomerated form which creates significant exposure.
A number of yard or general labor personnel handle materials at this smelter.
The smelting site is crowded with many piles of stored material lining
traffic-ways. As necessary employees bring material into the rotary furnace
Charge Storage and Preparation Building. These employees frequently wear
respiratory protection especially when handling dusty materials. Generation
of dust in this building is suppressed by the sprinkling and washdown con-
trols described earlier.
Since the rotary furnaces are operated on a batch rather than continuous
production schedule, charge preparation and handling is not a full time
activity. Filling of charge containers can be accomplished in several
minutes using a front-end loader. During this operation, employees are in-
structed to wear respirators. Aside from delivery of charge materials and
78
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charge container filling no other activities are conducted in this portion of
the building. Therefore, total employee exposure time in this area is only a
few hours each day. 3
Slag Handling—When slag is tapped into ladles from the rotary furnaces the
ladles remain briefly under the arched exhaust hoods. They are then moved
by lift truck to the indoor slag cooling area shown in Figure 23. Any fume
or smoke emitted from these slag ladles escapes into the work environment.
No local exhaust ventilation is provided for the cooling slag ladles. Em-
ployees do not wear respirators during slag handling. After the slag has
solidifed, portions of it may be removed from the ladles at the cooling area
or the ladles may be taken outside and dumped. A large front-end loader is
used to handle dumped slag. Wetted floors and yard surfaces are the only
controls which assist in suppressing potential particulate emissions from
solidified slag handling.
Finished Metal Handling—When finished metal ladles are filled from the
rotary furnaces they are moved from under the arched hood to cooling stations
between the furnaces. Local exhaust hoods are then swung over the ladles to
capture emissions during cooling. Emissions from the ladles during transfer
to the cooling station are uncontrolled. Employees do not wear respirators
when handling finished metal ladles.
Flue Dust Handling—Exposure to flue dusts collected from rotary furnace
operations occurs during baghouse maintenance, flue dust container (fabric
cubical) replacement and handling, and during charge prepartion. Aside from
wetted and washed down working surfaces, respirators are the primary means to
control employee exposure to flue dust.
Residues from Drains and Sumps—The paved yard surfaces and floors inside
operating and materials handling areas are sloped to drains and sumps.
These water collection points are routinely cleaned to remove deposits of
mud. Given the wetted nature of the material, dust generation is not an
immediate hazard. Splashes of particulate laden water, if allowed to dry
on work clothing, tools or work surfaces, could become a source of airborne
contamination.
Residues from Furnaces, Flues and Ductwork—During furnace shutdown the
rotary furnace and flue retractory is inspected, repaired and/or replaced.
These operations create opportunities for employee exposure. Employees do
wear respirators during maintenance operations.
Charging Emissions— .
Rotary furnace charging is performed by one furnaceman operating a lift
truck. Rotation of the furnace is stopped, the draft to the arched exhaust
hood is activated, the front access charging door of the furnace Is opened,
the roll-up door at the charge container resting deck is raised, and charge
containers are emptied one by one into the furnace.
79
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Emissions from the charging operation emanate from the furnace charging
door and rise into the arched hood. If the charge container is not completely
righted before being withdrawn from the furnace, buoyant fumes and smoke
can be trapped under the inverted container and released when the container
is righted. If the container is righted outside the influence of the
arched hood, these emissions escape into the workplace.
Only the furnaceman who operates the lift truck is directly involved
with furnace charging. He is not directly exposed to charging contamination
which emanates from the charging door. He can be exposed to fugitive
emissions which escape the arched hoods or which are entrained by the charge
containers as they are withdrawn from the furnace. Charging requires less
than 30 minutes to complete and may involve 10 to 15 tons of material.
The furnaceman performing this operation does not wear a respirator.
Slag and Metal Tapping—
When the furnace is ready to tap, its rotation is stopped, the draft to
the arched hood is activated and a rolling work platform is positioned under
the arched hood. The furnace rotation is stopped at a point where one of the
three tap holes is positioned above the fill level in the furnace but within
easy reach of a furnaceman when standing on the rolling work platform. A sledge
hammer is used to loosen a metal rod with a flat head which is lodged in
the center of the taphole refractory plug. This rod is removed when loosened.
The furnaceman who performs the tapping operation then wears a faceshield
while using a pneumatic hammer and bit to clean out the refractory material
from the taphole. This tapping operation takes several minutes during which
time the furnaceman is close to the end of the furnace where he is exposed
to radiant heat, noise from the pneumatic hammer, and potentially to emis-
sions from the tap hole refractory and furnace interior which escape from
the taphole. A respirator is not worn during this operation.
Once the taphole has been opened the rolling work platform is moved away
and a slag ladle is positioned under the arched hood using a lift truck. From
a position outside and adjacent to the process control room, a furnace man
operates the controls which govern furnace rotation. A second furnaceman
stands a few meters from the slag ladle to observe the filling of the
ladle. The furnace is rotated and slag is poured. When the ladle is nearly
full the furnace is rotated to stop the flow of slag. A lift truck removes
the filled slag ladle from under the arched hood and deposits it at the slag
ladle cooling area shown in Figure 23. An empty slag ladle is then moved
into position.
Emissions from the tap hole rise into the arched hood. Emissions from
cooling slag ladles escape into the work environment. Employees do not wear
respirators during this operation.
Finished metal is tapped after slag. The same taphole is used for both
metal and slag tapping. An overhead crane is utilized to move finished metal
ladles. The overhead crane is operated by a pendant control. The movable
sections of the arched hood are retracted to allow the cables from the over-
head crane to pass and close positioning of the ladle. When a ladle is filled
80
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it is manually skimmed using a long handled hoe like instrument. The crane
is then used to move the filled ladle to its cooling station where a local
exhaust ventilation hood is provided.
Emissions during metal pouring rise into the arched hood. Emissions
from the ladle during its transfer to the cooling station escape into the
workplace. Employees do not wear respiratory protection when pouring and
handling finished molten metal.
Once the finished metal has frozen in the ladle, the crane is used to
remove the metal ingot and transfer it to the stockpile area shown in
Figure 23.
The furnace taphole is closed using refractory mud/clay and the central
metal rod.
Engineering Control Evaluation
The engineering controls of employee exposure to lead and antimony
associated with rotary furnace operation were evaluated using three sources
of information. They are:
• Engineering measurements and design considerations
• Observations
• Air sampling information
These information sources will be discussed where applicable in conjunc-
tion with the control evaluated.
Charge Materials Receiving, Storage and Preparation—
Engineering Measurements—The engineering controls of interest are: 1) the
use of sprinklers to suppress dust levels in yard areas and inside the Charge
Storage and Preparation Building, and 2) the separation of these activities
from rotary furnace operations. These controls were evaluated through ob-
servation and air sampling.
Observations—The floors of the Charge Storage and Preparation Building were
observed to remain wet. Storage piles in bins were moistened. Movement of
the front-end loaders within this building does not create visible generation
of airborne dust. The roll-up doors to the Charge Storage and Preparation
Building were opened and closed as necessary to allow flow of materials.
Air Sampling—To obtain some limited information concerning the effectiveness
of charge materials storage and handling controls, air samples were collected
at two inside locations near the roll-up doors to the Charge Storage and
Preparation Building. The results of this air sampling are shown in Table
25. Lead-in-air concentrations of 120 and 220 Pg/m3, and antimony-in-air
concentration of less than 17 UgM3 and 15 yg/m3 were measured. These values
are not high considering the fact that flue dust is handled in this area.
81
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TABLE 25. LEAD AND ANTIMONY-IN-AIR CONCENTRATIONS ASSOCIATED WITH ROTARY
FURNACE OPERATIONS*
Sampling Lead-in-air Antimony-in-air
Job/location** interval cone, yg/m3 cone. pg/m3.
Breathing Zone - Samples
Furnaceman (HL) 6:06a - ll:lla 290 <24
Furnaceman (HL) ll:lla- l:45p 180 <47
Furnaceman (EJ) 6:04a - ll:15a 180 <16
Furnaceman (EJ) ll:15a- l:45p 180 <47
Furnaceman (SJ) 6:04a - ll:10a 170 33
Furnaceman (SJ) ll:10a- l:45p 130 <36
Yardman (NN) 6:06a - l:48p 200 <14
Area Samples - Rotary Furnace Operating Area
Rotary Furnace 6:07a - 2:05p 42 16
Control Room(l)
Outside Control 6:10a - ll:12a 86 <23
Near Center of
Furnace Area(2) ll:12a- l:56p 59 <46
Between Rotary
Furnace, Near 6:02a - ll:14a 97 17
Firing End of
Left Furnace(3) ll:14a- l:56p 32 42
Area Samples - Charge Storage and Preparation Building
Charge Preparation
Building Near 6:20a - 2:00p 120 17
Door to Yard(4)
Charge Preparation
Building Near 6:16a - 2:00p 220 15
Door to Furnace
Area(5)
*
Samples were collected on cellulose acetate membrane filters with 0.8y pore
size and analyzed atomic absorption spectrophotometry (P & CAM 173)
** Refer to Figure 23 for location of area sampling stations.
82
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Rotary Furnace Exhaust Ventilation Controls—
Engineering Measurement—The exhaust ventilation system is schematically
depicted in Figure 26. Evaluation of this system involved measurement of
air flows at several strategic points in the system. As with all ventila-
tion systems of this general type, it was not feasible to make measurements
at every point of interest in the system. Physical access was the primary
restraint in this regard.
Figure 26 shows the points at which ventilation measurements were made.
Where appropriate, hood entry coefficients were estimated and are presented
in Table 26. Performance data concerning the arched hood and ladle cooling
hood are presented in succeeding sections.
Observations—The rotary furnace exhaust ventilation system was found to be
in good repair. No serious dents or malformations in ductwork were found.
The system is constructed of heavy gauge steel.
During the day this system was evaluated, problems were encountered with
the baghouse bag cleaning mechanism. A portion of the baghouse jammed in
the cleaning cycle mode which resulted in significantly reduced draft to the
furnaces while repairs were made. Emissions were observed to escape from
the arched hoods during this period. These emissions visibly contaminated
the rotary furnace operating area for over an hour.
The day prior to process evaluation, the electric damper behind the
arched hood on one of the rotary furnaces broken down and required repair.
During the repair period significant quantities of air contamination escaped
into the workplace. Also during this workday a major spill of finished
metal occurred when the receiving ladle was accidentally overfilled. The
metal spilled out onto a wetted floor which caused generation of copious
quantities of steam but no serious splashes or projection of hot metal
occurred.
Handling of flue dust in fabric cubical containers appeared to involve
significant exposure to flue dust. Connection of the collecting containers
to the hoppers of the baghouse was not dust tight.
^Sffi^-sss.'sss n»= =£- -
~ •
-------
Furnace to flue
gap hood
Electric
damper
Ladle
cooling hoods
.11 J
Prime air mover
Furnace
to flue
gap hood
Electric
damper
Charging and tapping hoods
02-4464-01
Figure 26. Overview of rotary furnace ventilation controls
and key to ventilation system test points.
84
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TABLE 26. RESULTS OF TESTS IN ROTARY FURNACE VENTILATION SYSTEM*
Hood entry coefficient Ce**
TI 0.58
T2
T3
*Air flow measurements were made using a pitot tube and inclined manometer;
in-duct velocities, flow rates, temperature, and pressure data were con-
sidered proprietary and are not reported.
** /vp
Ce = W "cF~ > where SPt, = hood static pressure
If SPh h
85
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Two air samples were gathered from each employee's breathing zone and at
each location in the rotary furnace operating area. The baghouse malfunction
occurred during the 6:00 a.m. to 11:00 a.m. work period. Measured air con-
tamination was generally more significant during this period.
As can be seen from the data, employee exposures to lead-in-air were
found to range from 130 to 290 yg/m3 on the day evaluated. Only one
quantifiable employee exposure to antimony was measured (33 yg/m ). Other
samples contained less than the detectable limit of antimony. Work area
samples showed lead-in-air concentrations ranging from 32 to 97 yg/m .
Measurable concentrations of antimony ranged from 16 to 42 yg/m3. Relatively
higher contaminant concentrations were found in employee breathing zones as
compared to work area samples. This suggests that employees are exposed to
contaminant sources during their work activities. Exposure involves contami-
nant concentrations which are higher than the background workroom contamina-
tion.
Rotary Furnace Charging and Tapping Hood—
Engineering Measurements—Figure 25 presents a sketch of the rotary furnace
charging and tapping hood. The hood consists of a stationary section and two
retractable arch sections which function in conjunction with crane operation.
Air is exhausted from this hood through wide slots which are distributed
over the front side of the arch in the stationary portion of the hood.
These slots are approximately 10 cm (4 in.) in width. An Alnor® Velometer
was utilized to measure air velocities at the lowest three slots on each
side of the arch. Radiant heat and physical access prevented measure-
ments at all slot openings. Slot velocities ranging from 3.3 to 7.6 m/s
(650 to 1500 fpm) were measured with lowest velocities found at the bottom
slots.
Physical access problems precluded measurement of air flow and static
pressure in the ductwork directly behind the electrically operated damper.
An air flow measurement was made at point TZ shown in Figure 26. Air flow
at this point is the sum of air entering the arched charging and tapping
hood and air entering the hood enclosing the furnace to brick flue
connection. It is estimated that approximately 6 m3/s (13,000 cfm) enters
through the arched charging and tapping hood.
Observations—A complete charging of each furnace was observed. Emissions
which emanated from the charging door were observed to rise into the arched
hood and enter the exhaust slots. A relatively small amount of contamination
was observed to escape from the top front of the hood. Wisps of smoke and
fume were also observed to escape from the small gap between the retractable
and stationary sections of the arched hood. These emissions rose into the
workplace and were diluted.
During insertion and extraction of charge containers through the
furnace charging door, varying amounts of* contamination were observed to
escape from the arched hood. Most of the escaping contamination appeared to
be entrained by the charge containers. This problem was most significant
when charge containers were not completely righted before extraction from
the furnace.
86
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Several iterations of tapping both slag and metal were observed. Slag
tapping requires several minutes to complete and was observed to involve
between six and twelve slag ladles. Emissions from the tap hole anlslag
ladle were observed to rise into the arched hood and be collected. Only
minor amounts of fume were observed to escape into the workplace during
pouring of slag into ladles.
A crust was observed to form on the slag almost immediately. However,
visible fume/smoke was observed to emanate from each slag ladle as it was
moved by forklift to the cooling area. While cooling smaller and smaller
amounts of emission were observed to escape from the ladles for several
minutes.
During slag tapping, one furnaceman operates the furnace rotation
controls, one moves slag ladles with a lift truck, and a third observes
ladle filling and signals the man controlling furnace rotation. Aside from
walking by cooling ladles of slag, these men were not observed to be
directly exposed to emissions from slag tapping. While slag is poured from
the furnace, these men observe from a distance of several meters.
Finished metal tapping produces seemingly larger quantities of fume.
This fume emanates from the tap hole and ladle as it is filled. The
arched hoods were observed to capture practically all of the metal tapping
emissions when metal was poured at a less than maximum rate. When the
furnace was rotated to produce very rapid pouring, a relatively small but
seemingly important quantity of fume was observed to escape capture by the
arched hood.
Some direct exposure of employees to fumes from molten metal was
observed during the skimming of the metal and during its movement to the
cooling station using the overhead crane. Both of these operations are
conducted with employees working within three meters of the ladle. This
proximity provides the opportunity for exposure to fumes which are being
entrained by room air currents. Another similar exposure was observed when
the crane hooks were removed at the ladle cooling spot and the exhaust hood
was swung over the ladle.
When the retractable arches of the charging/tapping hood are raised,
fumes emanating from the filled ladle of metal are not completely captured
by the stationary portion of the hood. Fume emission at this time is not
vigorous, but escaping fumes, etc. do contribute to background contamination.
Rotary Furnace Ladle Cooling Hood-- _
Engineering Measurements—Figure 27 presents a sketch of one finished metal
ladle cooling hood used in the rotary furnace operating area. Hood dimen-
sional and performance data are contained in Figure 27 and Table 26. As can
be seen from the figure, this is a slotted hood which spreads the capture
zone around the perimeter of the ladle.
87
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Duct fins for
structural
support of hood
oo
oo
Swivel bearing
Inside diameter
19.7 cm (7.75 in)
D Finished
letal ladle
Hood Entry Coefficient
Ce - 0.58 N
Air flow measurements
(at chains) = 0.51-1.3 mps
(100-250 fpm)
face
slot
5.1-10 mps (1000-2000 fpm)
Hood radius
80 cm (31.5 in)
Radius to slot
64.8 cm (25.5 in)
Side elevation of finished
metal ladle cooling hood
Detail of slot design inside hood
02-4465-01
Figure 27. Finished metal ladle cooling hood.
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Obseryations-Once the hood was positioned over a ladle of cooling metal, no
emissions were observed to escape capture by the hood. Smoke generated by
Ihf i H ?h Smt6^ KS St the Perimeter of the ^od was observed to flow into
the hood through the hanging chains.
Hood Enclosing the Furnace to Flue Connection—
No quantitative evaluation of this hood could be made. It does enclose
the gap between the furnace and flue as shown in Figures 25 and 26, and no
emissions were observed to escape this hood.
Other Industrial Hygiene Considerations
Personal Protective Equipment—
Similar protective clothing and equipment policies as described for SB
furnace operations are followed in the rotary furnace work area.
Employee Hygiene—
See discussion associated with SB furnace operations.
Biologic Monitoring—
No results of blood lead monitoring were obtained for employees working
in the rotary furnace department. Refer to the discussion associated with
the SB furnace for a description of biologic monitoring policies.
Noise Level Measurements—
A sound level survey was made of the operations associated with the
rotary furnaces. The results of this survey are shown in Table 27. As can
be seen from the data, no serious noise sources were discovered.
Control Critique
The engineering controls provided for rotary furnace operations are
well designed and maintained. When functioning properly and used appropri-
ately by employees, these controls capture the vast majority of emissions
which are produced during charging, furnace operations, tapping and
finished metal cooling.
Several opportunities remain for improvement of fugitive emission
control. These opportunities have been eluded to in the past and
primarily involve work practices and operational changes. Emissions from
cooling slag ladles could be reduced by placing covers over the ladles or
relocating the cooling area out-of-doors. Emissions from metal tapping
could be reduced by pouring the metal more slowly from the furnace into the
ladle. Additional emission control could be accomplished by allowing the
finished metal ladles to remain under the arched hoods for a longer period
before moving to the final cooling station.
Housekeeping in the rotary furnace work area was good. Frequent wash-
down of floors appeared to significantly reduce potential entrainment of
settled particulate into workplace air.
89
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TABLE 27. RESULTS OF NOISE MEASUREMENTS MADE IN ASSOCIATION WITH ROTARY FURNACE OPERATIONS
vo
o
Location
no.*
1
2
3
4
5
Description of measurement Noise type1
location and/or operation S/I
Between rotary furnaces
Burner end of rotary furnace
Near rotary furnace combustion
air fan
Pouring end of rotary furnace
Beside rotary furnace next to
Charge Storage and Prepara-
tion Building
S
S
S
S
S
Exposure2
C/I
I
I
I
I
I
Sound
dba
77
82
85-86
77-78
81
level3
dbc
84-86
89
92-93
83-84
86
*Refer to Figure 23 for location of sound level measurement.
1Noise type: S = Steady, I = Impulse or Impact.
2Exposure: C = Continuous, I = Intermittent.
3Sound level: Measured in decibles on the A and C weighting networks
of a Type 52A sound level meter.
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Employees should be instructed to wear respirators during and following
periods of process upset, failure of ventilation controls or during spills?
POT INDUCTION FURNACE
A variety of small furnaces are used to produce relatively minor quan-
tztles of specialty alloys at this smelter. The ventilation controls associ-
ated with one, small, tilting electric induction furnace proved to be
interesting and are discussed here.
Description of Equipment and Controls
The furnace studied is used to produce specialty copper based alloys.
An overview of this furnace and its associated exhaust ventilation hood are
shown in Figure 28.
This furnace is located in a building with several other furnaces en-
gaged in production of various alloys. The furnace is of tilting type which
facilitates pouring of its molten contents into a transfer ladle.
The furnace is provided with a slotted hood suspended over the furnace;
this hood can be moved so that emissions from the furnace in its level and
tilted position can be controlled.
Description of Emission Sources and Potential Exposures
Fumes and smoke emanate from the top of the induction furnace during
furnace charging, meltdown and pouring. Due to its small size the furnace is
manually charged. Containers of scrap (mostly plant scrap) are dumped into
the furnace. In some instances a scoop shovel is used to handle fine materi-
als. Ingots of known composition may also be added to bring the melt to
proper specification.
During charging the furnaceman can effectively add materials to the
furnace without being directly exposed to the plume of emissions emanating
from the furnace. This can be accomplished by moving the hood to various
positions over the furnace to allow the necessary access. Initial charging
usually will require only several minutes to complete. As the material
melts additional materials may be added at varying intervals.
While the furnace charge is melting, the furnaceman tends to other
operations located in the same building. This employee returns to the furnace
periodically to observe how the melt is preceding.
As the melt nears readiness for pouring, the furnace man skims the molten
metal surface and moves the transfer ladle into position to receive the»lt«u
alloy. Again the overhead slot hood can be manuevered to prevent the employee
from being directly exposed to the plume of fumes emanating from the furnace.
91
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Rectangular duct
Height: 40.6 cm (16 in)
Width: 51 cm (20 in)
Air flow measurements
SP • -132 mm HjO
(-5.2 in H20)
Stiffeners
102 cm
(40 in)
Swivel bearing connection
to exhaust ductwork
Square bar stock for
structural support
of ductwork and hood
Hood Entry Coefficient
Ce - 0.63
Swivel bearing
Tilting furnace housing
(housing lifts on this
end to pour contents
of furnace)
10 slot exhaust pickups
2 cm (0.75 In) in width
slot
5-20 raps
(1000-3900 fpm)
Pot furnace
Fold over
furnace lid
Direction of
housing tilt
Hood width: 178 cm (70 in)
Hood depth: 170 cm (67 in)
(front to back)
02-4466-01
Figure 28. Pot induction furnace hood.
92
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During pouring of the furnace, the furnace and its housing deck tilt as is
indicated in Figure 28. The overhead exhaust hood is moved to allow this tilt-
ing but still remain in position to capture emissions. Once the molten metal
is poured into the transfer ladle, the ladle is moved out from under the hood.
No control is provided for emissions from the ladle until it reaches its pour-
ing station. The employee who tends this furnace is exposed to fugitive emis-
sions from this furnace operation and to fugitive contaminants from other
equipment in the same general work area.
Engineering Control Evaluation
Engineering Measurements—
The pot induction furnace hood was evaluated by measuring slot velocity
inside the hood and air flow in the duct leading away from the hood. Slot
velocity measurements were made using an Alnor® Velometer. A pitot tube and
manometer were used to make air flow measurements at the point indicated in
Figure 28.
As indicated by the results of the measurements, a large volume of air
is moved through this hood resulting in relatively high slot velocities.
Observations—
When positioned over the pot furnace, the hood appeared to very effec-
tively capture all visible contamination. •
During charging, skimming and pouring the furnaceman did not always take
full advantage of the mobility of the hood to help preclude his contact
with emissions. Better hood positioning could have been possible during the
period observed.
Ventilation smoke tubes were used to observe air flow at all sides of the
hood. Smoke was observed to be swiftly pulled into the hood.
Air Sampling—
Due to the presence of multiple emission sources in the same general work
area, air samples were not gathered in the evaluation of this hood.
Control Critique
The hood appeared to function well when properly utilized by the furnace-
man. Emissions from the transfer ladle as it is moved to casting lines could
be lessened by placing a lid over the ladle. This would also help to reduce
the possibility for splashes of molten metal to occur.
93
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APPENDIX
BLOOD/LEAD DATA SUPPLIED BY BERGS0E MANAGEMENT
6th October, 1978
NG/aju
3-170/20
Radian Corporation
8500 Shoal Creek Blvd.
Austin, Texas 78756
U.S.A.
Att.: MX. Richard Coleman
Dear Rick,
As agreed during your visit here last week, we shall provide
statistical information about the blood-lead measurements on
our personnel working in the SB furnace department.
Regular lead-in-blood measurements have only been made over
the last two years, and they have not been consistent at all
times. For this reason we prefer to give you only the most
recent figures, i.e. the lead-in-blood result of the latest
sample drawn from each of the 27 employees up to mid Septem-
ber 1973. They all date from the latest few months.
The SB furnace has been in operation for about 3 years, and
most of the people have only worked in that department. Three
men have been transferred from other departments less than a
year ago, but no one later than January 1978.
Lead-in-blood figures for period .up to week 78/37
(dated 17th September 1978)
^kg/100 ml No. of persons, and working history (Note 11
i 30 4, worked less than 6, months (Note 21
31-40 1, worked about 1 year
41-50 5, worked 1% - 2 years
51-60 7, worked 2-8 years
61-70 8, worked 1^-4 years (Notes 3 and 4)
71-80 2, worked 2 and 3 years respectively
Total 27 persons
94
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6th October, 1978
page 2
Radian Corporation
Richard Coleman
Note 1. All samples wera analysed by a O.K. laboratory
(NOSH). Recent interealibrations with other laboratories
strongly indicate that the results from NOSH are significantly
higher than those of the official Danish work Safety Labora-
tory (AMT). The statistical difference is no less than 29%,
and if it were deducted it would bring the above figures
below 60 *g.
Note 2. Tests taken upon employment.
Note 3. One man in this group worked 21 years in the plant.
4. One of these tests was crosschecked with three other
'Oratories, all finding 10-15 -g less.
Note 4
labors-
Yours sincerely,
PAUL BERGS0E 1 S0N A/S
Niels Gram
95
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/2-80-022
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Evaluation of Paul Bergsoe & Son Secondary Lead Smelter
5. REPORT DATE
January 1980 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Richard T. Coleman & Robert Vandervort
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
Radian Corporation
8500 Shoal Creek Blvd.
Austin, Texas 78766
11. CONTRACT/GRANT NO.
IAG# EPA-78-D-X0309
NIQSH Contract #210-77-0008
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory
Office of Research and Development
U. S. Environmental Protection Agency
Cincinnati, OH 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final: 10/78-10/79
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report presents the findings of an investigation performed to obtain data
concerning fugitive and workroom emissions from secondary lead smelters. The results
are being used within both NIOSH and EPA as part of a larger effort to define the
potential workplace/environmental impact of emissions from this industry segment and
the need for improved controls. The findings will also be useful to other agencies
and the industry in dealing with control problems. Either the Metals and Inorganic
Chemicals Branch of the USEPA or the Division of Physical Science and Engineering of
NIOSH should be contacted for any additional information desired concerning this
program.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Secondary Lead Smelting
Lead
Fugitive Lead Emissions
Occupational Exposure
Bergsoe Agglomeration
Furnace
Fugitive Lead Emission
Controls
8. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
110
SO. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
96
U.S. GOVERNMENT PRINTING OFFICE: 1980-657-146/5597
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