United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 2771 1
Research and Development
EPA-600/S2-81-036 July 1981
Project Summary
Hot Metal Desulfurization,
BOF Charging, and Oxygen
Blowing: Level 1
Environmental Assessment
C W Westbrook
An EPA/IERL-RTP Level 1 environ-
mental assessment of fumes generated
at one plant during external hot metal
desulfurizaton (HMDS), hot metal
charging to the basic oxygen furnace
(BOF), and during oxygen blowing of
the BOF was performed. The purpose
of the work was to develop prelimi-
nary information on the organic and
inorganic matter generated in these
processes.
Fumes generated (before emission
control) during HMDS contain about
0.64 kg of particulate and 1 x 10 3 kg
of organic/Mg of metal desulfurized
(1.27 and 2 x 10~3Ib/ton, respectively).
Although a small amount of possibly
carcinogenic polynuclear aromatic
hydrocarbons (PNA) were detected,
none of the organic categories was
found in sufficiently high concentra-
tion to be of environmental concern.
Sufficiently high concentrations of
some metals (e.g., lead, mercury,
antimony, and arsenic) were found to
require highly efficient dust capture
and environmentally sound disposal.
Fumes generated (before control)
during BOF hot metal charging con-
tain about 5.3 x 10 2 kg of particulate
and 5.8 x 10~4 kg of organic/Mg (of
hot metal charged (10.6 x 10 2 and
11.6 x 10~" Ib/ton, respectively). No
PNA was detected and none of the
organic category concentrations is
high enough for environmental con-
cern. Sufficiently high concentrations
of some metals (e.g., arsenic, lead.
mercury, and cadmium) were found to
require good dust capture and disposal.
Dust from the BOF baghouse, which
collects fumes from hot metal transfer
and charging, scrap charging, tapping,
and slagging, also contained about
100 mg PNA/kg (0.2 Ib/ton) of dust.
The source of the PNA was not deter-
mined.
About 11 kg of particulate and
0.004 kg of organic/Mg of steel (22
and 0.008 Ib/ton, respectively)
processed in the BOF is captured by
the primary emissions control scrubber
during the oxygen blow period. Al-
though no PNA was found in the
scrubber water, a small amount (<1
mg/kg solids) was found in the solids
removed from the primary clarifier.
None of the organic concentrations is
high enough for environmental con-
cern. The concentrations of lead,
selenium, manganese, copper, and
zinc in the clarified recycle water
would be of concern if discharged to
surface waters.
This Project Summary was devel-
oped by EPA's Industrial Environ-
mental Research Laboratory, Research
Triangle Park, NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering information at back).
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Introduction
This report describes the results of an
EPA/IERL-RTP Level 11 assessment of
fumes generated at one plant (Kaiser
Steel Company, Fontana, CA) in three
phases of the manufacture of steel. The
Level 1 approach, which measures
particulates, inorganics, and organics,
is a unified approach designed to indicate
whether or not significant amounts of
hazardous materials may be generated,
and possibly emitted, by a process. The
data obtained are useful in assessing
potential environmental problems and
allow priorities for future research
efforts to be established.
The purpose of this study is to deter-
mine if the processes involved, rather
than the plant as a whole, are potential
generators of hazardous materials.
Therefore, this work concentrates pri-
marily on characterization of the fumes
generated by the processes rather than
on measuring discharges to the envi-
ronment As such, the results can be
extrapolated, with appropriate caution,
to similar processes at other plants.
The processes included in this study
are external desulfurization of molten
metal produced by the blast furnace,
charging of hot metal into the basic
oxygen furnace (BOF), and oxygen
blowing of the BOF .
Summary
Sampling and analysis of fumes
generated during external desulfuriza-
tion of blast-furnace-produced hot
metal, during hot metal addition to the
basic oxygen furnace (BOF), and during
oxygen blowing of the BOF at the plant
were conducted. EPA/ IERL-RTP Level
1 protocols1 were used. Statements
regarding the degree of environmental
concern are based on comparison of the
data obtained with published MEGs
data.2
Hot Metal Desulfurization
Molten metal produced by the blast
furnace is cast into torpedo rail-cars. If
the metal sulfur content exceeds desir-
able levels for specific further process-
ing, the sulfur is removed from the
metal, while still in the torpedo car, at
the hot metal desulfurization station
(HMDS). To accomplish this, appropriate
amounts of calcium carbide (CaCa) and
calcium carbonate (CaCOs) are blown
into the metal (with nitrogen gas) through
a lance submerged in the metal. Fumes
generated in the process are collected
by side-draft hoods and collected in a
baghouse. One to three cars can be
desulfurized simultaneously. All side-
draft hoods operate during desulfuriza-
tion regardless of the number of cars
being processed.
The Source Assessment Sampling
System (SASS) was used to collect
samples during four periods of desulfu-
rization. The sample was taken in the
duct before the fume entered the bag-
house and, thus, represents the amount
of fumes generated by the process and
not the amount emitted to the environ-
ment. A sample of the dust collected by
the baghouse was also obtained and
analyzed.
Table 1 isasummaryoftheparticulate
and total organic matter results.
BOF Hot Metal Charging
After scrap metal is charged into the
BOF vessel, molten iron is added. The
fumes generated during this addition
are collected by two side-draft hoods
and captured in a baghouse. The bag-
house also captures fumes generated
during hot metal transfer, reladling,
scrap charging, tapping, and slagging.
Samples were taken from one of the
charging fume control dusts with the
SASS train. Twenty-four periods of hot
metal charging were sampled to obtain
a reasonable amount of sample. Since
the SASS train was not "cleaned up"
(samples recovered) between runs, data
for individual charges were not obtained.
Also obtained and analyzed was a
sample of the dust collected by the
baghouse. Results from this sample
cannot be compared to the SASS train
samples since fumes from other sources
enter the baghouse.
Given m Table 2 are the results
obtained for particulates and total
organics.
BOF Oxygen Blowing
After hot metal is charged, oxygen is
blown into the vessel (fluxes are also
added) to reduce the carbon content and
produce steel. At Kaiser, a suppressed
combustion system is used and results
Table 1. HMDS Total Paniculate and Organic Matter Summary
Sample Type
Concentration in Gas
mg/Nm3
Generated,
kg/Mg Steel Desulfurized
A. Paniculate
Probe, cyclone washes
>10 /j cyclone dust
>3 (i cyclone dust
>1 fj cyclone dust
<1 [i dust (filter)
TOTAL:
175
3123
1754
900
298
6250
0.018
0.318
0.179
0.092
0.030
0.637
B. Organic
All particulates
Organic module
TOTAL:
3.8
9.9
3.87 x 10'
6.21 x 10'
1.01 x 10'
Table 2. BOF Hot Metal Charging Paniculate and Organic Summary
Concentration in Gas
Sample Type mg/Nm3
A.
B.
Paniculate
Probe, cyclone washes
>10 /J cyclone dust
>3 (j cyclone dust
>1 (j cyclone dust
<1 it dust (filter)
TOTAL:
Organic
All particulates
Organic module
TOTAL:
98.6
274.0
205.8
123.9
85.1
787.4
0.7
7.9
8.6
Average Generated,
kg/Mg Hot Metal Added
6.65 x 10'3
1.85 x 10'2
1.40 x 10'2
8.42 x 10'3
5.77 x 10'3
5.33 x 10'2
4.7 x 10'5
5.4 x 10'* i
5.8 x 10'*
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in gas produced during oxygen blowing
with a high (>20 percent) carbon mon-
oxide content. Direct sampling of the
gas was not done. The gas produced is
cleaned in a scrubber. Samples of the
water going to and coming from the
scrubber and solids removed from the
water treatment clarif iers were obtained
and analyzed. The results are given in
Table 3.
Conclusions
1. Fumes generated (before emission
control) during external hot metal
desulfurization (HMDS) contain
about 0.64 kg of paniculate and 1 x
10"3 kg of organic/Mg (1.27 and 2 x
1CT3 Ib/ton, respectively) of metal
desulfurized.
2. Organics in the HMDS fumes are
predominately aliphatic hydrocar-
bons, ethers, ketones, and esters. A
small amount of polynuclear aro-
matic hydrocarbons (possibly in-
cluding some carcinogens) was
detected. None of the organic cate-
gory concentrations are high enough
to be of environmental concern.
3. Significantly high concentrations of
lead, mercury, barium, antimony,
strontium, arsenic, copper, manga-
nese, and chromium were found in
the HMDS fumes. It is important
that fume collection and baghouse
dust collection efficiency be high.
4. Dust captured by the HMDS bag-
house is sufficiently high in content
of strontium, chromium, and arsenic
to be of concern for landfill disposal.
(The dust is recycled at the plant
tested.)
5. Only about 10 percent of the organic
matter generated by HMDS is cap-
ture by the baghouse.
6. Fumes generated (before emission
control) during hot metal charging
to the basic oxygen furnace (BOF)
vessel contain about 5.3 x 10~2 kg of
paniculate and 5.8 x KT4 kg of
organic/Mg (10.6 x 10"2 and 11.6 x
10 4 Ib/ton, respeci.vely) of hot
metal charged.
7. Organics in the BOF hot metal
charging fumes are predominately
esters, ketones, and ethers. The
concentrations found at this plant
are not high enough for environ-
mental concern.
8. Significantly high concentrations of
strontium, selenium, arsenic, cop-
per, chromium, lead, mercury, bar-
ium, antimony, and cadmium were
found in the BOF hot metal charging
fumes. It is important that fume
collection and capture efficiency be
high.
9. Dust captured by the BOF secondary
emissions control baghouse is suffi-
ciently high in content of the metals
cited in 8 above to be of concern for
landfill disposal. (The dust is recycled
at the plant tested.)
10. The organic content of the BOFbag-
house dust was about 540 mg/kg
(1.1 Ib/ton) of dust. As much as 20
percent of the organic could be
polynuclear aromatic hydrocarbons,
and could include some known
carcinogens. This suggests possible
environmental problems with the
disposal of the dust and indicates
that the baghouse outlet should be
tested to determine PNA emissions.
11. About 11 kg of paniculate and
0.004 kg of organic/Mg (22 and
0.008 Ib/ton, respectively) of steel
processed in the BOF is captured by
the primary emissions control
scrubber during the oxygen blowing
period.
12. Organics in the BOF scrubber water
were mostly silicones, ethers, alco-
hols, ketones, and similar com-
pounds. No PNA was found in the
scrubber water; however, a small
amount (<1 mg/kg solids) of PNA
was found m solids removed from
the primary clarifier. None of the
organic categories, in either the
clarified recycle water or scrubber
discharge water, was in sufficient
concentration to be of environmen-
tal concern.
Table 3. BOF Oxygen Blowing Water Treatment Samples
Sample Type
In Sample, kg/min
Solids Organic
kg/Mg Steel Processed
Solids Organic
Scrubber discharge water 137 0.36
Recycle water 1.5 0.32
Net Captured 11 0.004
Primary clarifier solids = About 7.1 mg organic/kg solids.
Secondary clarifier solids = About 66.1 mg organic/kg solids.
13 The concentrations of lead, sele-
nium, manganese, copper, and zinc
in the clarified water would be of
concern if discharged to surface
waters. (This water is totally recycled
at the plant tested.)
Recommendations
Although organic matter is generated
during hot metal desulfurization and the
data indicate a substantial fraction
(possibly >90 percent) of the organic is
not captured by the baghouse, the low
concentrations found indicate that no
additional work in this area is needed.
Significantly high concentrations of
some metals (including lead, mercury,
antimony, and arsenic) were found in
the fumes generated and dust captured.
Additional testing (e.g., leaching) may
be needed to assess the degree of
hazard if the dust is landfilled, rather
than recycled as for the plant tested.
The data suggest that additional work
may be needed to assess BOF secondary
fume generating processes (hot metal
transfer, scrap charge, tapping, etc.) and
possibly emissions from this source.
About 100 mg PNA/kg secondary emis-
sion control baghouse dust was found,
but PNAs were not detected in fumes
from hot metal charging. Testing should
include further analysis of the dust to
determine if it constitutes a hazardous
waste, testing of each process step to
determine which is generating the PNA,
and testing of the baghouse outlet to
determine if unacceptable amounts of
PNA are being released to the environ-
ment. Significant amounts of some
metals (e.g., arsenic, chromium, lead,
antimony, and cadmium) were found in
both the hot metal charging fumes and
in the secondary emissions control
baghouse dust.
The data suggest that little organic
matter is generated during BOF oxygen
blowing. No additional testing in this
area is recommended. The clarified
scrubber water (recycled at the plant
tested) contains sufficiently high con-
centrations of lead, selenium, manga-
nese, copper, and zinc to present prob-
lems if discharged to surface waters.
More accurate quantitation of the con-
centrations and masses generated may
be needed for plants where the water is
discharged rather than recycled.
References
1. Lentzen, D. E., D. E. Wagoner, E. D.
Estes, and W. F. Gutknecht. IERL-
RTP Procedures Manual: Level 1
* US GOVERNMENT PRINTING OFFICE 1961 -757-012/7227
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Environmental Assessment-Second
Edition. EPA-600/7-78-201 (NTIS
No. PB 293795), October 1978.
Kingsbury, G. L, R. C. Sims, and J. B.
White. Multimedia Environmental
Goals for Environmental Assess-
ment-MEG Charts and Background
Information Summaries—Vol.Ill-
Categories 1-12, EPA -600/7-79-
176a (NTIS No. PB 80-115108), and
Vol IV—Categories 13-26, EPA-
600/7-79-1 76b (NTIS No. PB 80-
115116), August 1979.
C. W. Westbrook is with Research Triangle Institute, Research Triangle Park NC
27709.
R. C. McCrillis is the EPA Project Officer (see below).
The complete report, entitled "Hot Metal Desulfurization, BOF Charging, and
Oxygen Blowing. Level! Environmental Assessment, "(Order No. PB 81-179 251;
Cosf $12 50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at.
Industrial Environmental Research Laboratory
U S Environmental Protection Agency
Research Triangle Park, NC 27711
i
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use S300
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