United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
*
Research and Development
EPA/600/S2-87/081 Jan. 1988
Project Summary
Destruction and Removal of
POHCs in Iron Making Blast
Furnaces
Radford C. Adams and Gregory J. Carroll
At least one steel company utilizes
organic waste liquids as a heat and
carbon content source to partially
replace the coke that is used to charge
the blast furnaces. The waste liquids
fed to the blast furnace are likely to
contain hazardous constituents.
Temperature and residence time in the
blast furnace favor total destruction of
the principal organic hazardous constit-
uents (POHCs) of the waste fuel, but
verification of destruction efficiencies
has not been attempted up to now.
Also, reduction reactions that occur in
a blast furnace may promote the
formation of products of incomplete
combustion (PICs).
Tests were conducted while feeding
waste fuel to a blast furnace located
at a major steel mill. The primary
objectives of the test program were to
determine the fate of the POHCs of the
waste fuel; to look for formation of
PICs, notably dioxins and dibenzofu-
rans; and to determine relative emis-
sions of volatile organic components of
waste oil from the waste fuel storage
tank compared with emissions of these
components from the combustor.
This Project Summary was devel-
oped by EPA's Hazardous Waste Engi-
neering Research Laboratory, Cincin-
nati, OH, to announce key findings of
the research project that is fully doc-
umented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
With the passage of the Hazardous and
Solid Waste Amendments of 1984, more
liquid hazardous wastes categories will
be banned from land disposal facilities.
At the same time, energy intensive
industries are continuously seeking new
sources of less expensive fuel. Because
many hazardous waste products can
readily be used as fuels, a market based
on these wastes has been developing in
the United States. Among the high-
temperature industrial furnaces and
processes that already burn hazardous
waste as supplemental fuel are cement
kilns, lime and dolomite kilns, clay
processing kilns, phosphate rock calcm-
ers and dryers, iron ore dryers, brick and
tile tunnel kilns, mineral wool furnaces,
glass melt furnaces, and steel blast
furnaces.
Organic waste liquids can be burned
in iron-making blast furnaces to provide
a twofold benefit to the user; not only
can they replace natural gas as a fuel
source, but they can also provide a
carbon source, thus partially reducing
coke requirements. This practice of
burning wastes in the furnace is also
attractive from a waste disposal view-
point since it offers high residence time
for destruction of Principal Organic
Hazardous Constituents (POHCs) in a
high-temperature environment.
Because the disposal of hazardous
wastes in industrial furnaces is currently
exempt from the Resource Conservation
and Recovery Act (RCRA) performance
regulations enforced at incineration
facilities, little attempt has been made
to determine how successful iron-
making blast furnaces are in achieving
destruction and removal of POHCs. To
gain further insight into this, testing was
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conducted during the burning of liquid
waste fuel in an industry-typical blast
.furnace located at LTV Steel's Indiana
Harbor Works, East Chicago, Indiana.
The primary objectives of this test were
as follows:
• Determine the destruction and rem-
oval efficiency (ORE) and fate of waste
oil POHCs by monitoring blast furnace
gas and combustor flue gas for iden-
tified POHCs.
• Determine formation of products of
incomplete combustion (PICs) and, if
detected, their fate.
• Determine relative emissions of vol-
atile organic components of waste oil
from the waste fuel storage tank
compared with emissions of these
components from the combustor.
As a secondary objective, the presence
of dioxins and dibenzofurans in the
emissions/effluent at levels greater than
one part per trillion was also
investigated.
Approach
The blast furnace system, depicted in
Figure 1, is used to produce molten iron
from iron ore and other iron-bearing
materials. A moving bed of iron ore,
carbon (as coke), and limestone descends
through the blast furnace tower. In the
combustion zone, located between the
descending bed and the hearth of the
furnace, oxygen of the hot blast air and
steam react with carbon to produce
carbon monoxide and hydrogen. Temper-
atures in the combustion zone exceed
3000°F. The hot CO and H2travel upward
through the descending bed. In the lower
part of the furnace where the temper-
ature is very high, the iron oxides are
reduced to elemental iron by the coke.
In the upper part of the furnace tower
where the temperature has decreased to
1700°F, the iron oxides are reduced by
the carbon monoxide and the hydrogen.
The molten iron and slag are collected
in discrete layers on the hearth of the
furnace and are removed through tap
holes at regular intervals.
Unconsumed CO and H2, which are
produced in excess to drive the iron oxide
reduction to completion, yield an off-gas
with a heating value of 90 BTU/SCF. To
recover this heat energy, about a third
of the off-gas is burned in stoves that
preheat the blast air, while the remaining
two-thirds is burned in process boilers.
Products of combustion from the stoves
are emitted to the atmosphere through
a stack.
For the purposes of the test, the set
of blast air preheating stoves was
considered to be a downstream combus-
tion process and was included in the
scope of the test. Sampling was per-
formed upstream and downstream of the
stoves while the process boiler streams
were not investigated.
Natural gas was originally used as th
fuel source for the blast furnace. This ha
been replaced by a waste oil mixtur
consisting of waste organic liquid!
supplied by Cadence Chemical Company
and Number 6 fuel oil.
The test plan consisted of three sarr
pling runs conducted on successive day
(8/15/84-8/17/84). Selected bias
furnace and stove set operating data fc
each of the three runs are summarize
in Tables 1 and 2, respectively.
Liquid waste feed characterization ma
be found in Table 3. Eleven detecte
compounds were selected as POHCs i
the test. This selection was based upo
concentration, toxicity, and degree <
chlorination of the compounds. Thos
POHCs with feed concentrations beloi
1000 ppm may yield suspect results fc
DRE because it is likely that emissio
rates for compounds with such low fee
concentrations will be below the dete(
tion limits. This inhibits verification c
DRE, which is determined as shown i
Figure 2.
The target for acceptable DRE perfoi
mance was chosen to be 99.99%, whic
is also the RCRA standard for incinei
ation of non-PCB wastes. DREs wer
determined across the blast furnace itse
and across the total system (blast f urnac
+ stove set).
A summary of the process stream
sampled and the analyses performe
may be found in Table 4.
Iron Ore
Coke
Limestone
Venturi
Cyclone Scrubber
Cooler
Slag Tap Metal Tap
Boiler
From Air Blower
Figure 1. Blast furnace process flow.
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Table 1 . Summary of Blast Furnace Operating Data
Average Value
Parameter Run 01 Run 02 Run 03
Blast Air Temperature. °F 1,743 1.770 1.756
Blast Air Flowrate, dscfm x103 116.5 116.6 116.2
Blast Air Pressure, psig 31.5 30.4 302
Total Oxygen in Blast. % 23.4 23.4 23.4
Flame Temperature °F (calculated) 3.389 3.487 3.402
Furnace Top Temperature °F 337 379 325
Top Gas Heating Value. Btu/scf (calculated) 907 89.3 91.5
Total Blast Gas Volume, scfm xW3 1283 127.1 127.9
Waste Oil Injection, gpm 60.6 59.5 60.4
Waste Oil Heating Value. Btu/lb 14.776 14.708 14.851
Table 2. Summary of Stove Operation Data for Periods of Blast Furnace Gas Combustion
Mean Blast Air/Fuel Mean Stove Temperatures
Stove Test Gas Flow Ratio Wall Dome Stack
Number Run (scfm) (scf/scf) (°F) (°F) f°F)
31 01 25.050 075 1.746 2.283 444
02 25,050 073 1.694 2.246 399
03 25.950 074 1.684 2,200 426
32 01 26,050 0.81 1.626 2.271 443
02 25,730 0.80 1,638 2,246 429
03 26,580 081 1.650 2,247 413
33 01 25,370 0.83 1,681 2,279 448
02 25.220 0.83 1.636 2,246 431
03 26,360 0.87 1,656 2,252 432
Table 3. Summary of Liquid Feed Data
Run 01 Run 02 Run 03
Waste Liquid/Fuel Oil Ratio .8 .6 6
Heating value, Btu/lb 14.776 14,708 14,851
Carbon, wt % 67.57 68.27 70.06
Hydrogen, wt % 9.58 9.20 9.28
Nitrogen, wt % 0.26 0.31 0.39
Chlorine, wt % 0.09 0.08 0.08
Sulfur, wt % 0.73 0.30 0.59
Ash, wt % 0.99 098 077
Oxygen, wt %, by difference 17.88 17.93 17.58
Water, wt % 2.90 2.93 1.25
10000 100.00 100.00
Average Mass
Compound Concentration (ppm by Weight) to Blast Furnace*
Run 01 Run 02 Run 03 Average (Kg/hr)
Methy/ene chloride 688 1,023 535 750 9.7
1.1-dichloroethene 1.071 1.880 690 1.213 15.7
Chloroform 33 469 259 254 33
1 .1 .1 -tnchloroethane 817 965 1.215 999 13.0
Tnch/oroethene 1.511 719 1.326 1.185 15.4
Benzene 569 547 543 553 7.2
Tetrach/oroethene 2.230 3,372 2,787 2,796 36.3
Toluene 65.417 53.342 49.901 56.220 731
m/p-Xylene 2.600 1,500 10.600 9.400 122
o-Xylene 9.500 3.300 3.050 5.280 68.8
Napthalene 810 1,100 730 880 114
Volumetric rate, gpm 606 599 604 602
Mass rate, kg/h 13.067 12,830 13.024 12,974
"Mass rate based on average waste/ oil feed rate of 60.2 gpm and specific gravity of 0.95 Feed
rates for individual test runs ranged from 59 5 to 60 6 gpm.
Results
DREs and Fate of Waste Oil
POHCs
A summary of the DREs may be found
in Table 5. The results have been
segregated into three groups: DREs for
POHCs having feed concentrations
greater than 1 000 ppm; DREs for POHCs
having feed concentrations less than
1000 ppm; and DREs for benzene and
methylene chloride. Benzene is looked at
separately because it is often found in
combustion emissions when not
detected in the scrubber feed; explana-
tions for this include benzene as an
artifact of one of the sorbents, and
benzene as a PIC. Methylene chloride is
singled out because of its high back-
ground concentration typically found in
hazardous waste destruction tests; it is
commonly used as a solvent during
sample train cleanup and analysis.
Across the blast furnace, the target
ORE of 99.99% was reached for 8 of the
18 1000+ ppm measurements. For the
cases in which feed concentrations were
less than 1000 ppm, three of nine DRE
measurements were greater than
99.99%. None of the six DRE measure-
ments across the furnace for benzene
and methylene chloride met the target.
Across the total system, DREs were
somewhat higher. The criterion was met
in 14 of the 18 1000+ ppm measure-
ments. For feed concentrations below
1000 ppm, three of nine DRE measure-
ments were greater than 99.99%. As was
the case with the blast furnace, none of
the DREs for benzene and methylene
chloride reached 99.99% across the total
system.
Using 99.99% as the criterion, suc-
cessful DRE was consistently achieved
for the following POHCs: trichloroethene
(across blast furnace and total system),
tetrachloroethene (blast furnace and
total system), toluene (total system only),
and o-xylene (total system only).
Analysis of the scrubber water for
semi-volatile POHCs found that, with one
exception, POHC concentrations were
either below the detection limit or did not
exceed concentrations in makeup water.
For Run 3, the mass rate of toluene in
the blowdown, corrected for concentra-
tions in the makeup, was 7800 g/hr or
about 1 percent of the toluene in the feed.
PIC Formation and Fate
Scrubber makeup water, scrubber
discharge water, and blast furnace and
stove off-gas were sampled for volatile
3
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Blast Furnace
Out, g/h
Waste Feed
In, g/h
System ORE, =
(Waste Feed In, g/hh
- (Stove Waste Out, g/h),
(Waste Feed In, g/h),
Blast Furnace ORE, = fWaste Feedln' 9/hh '(Blast Fumace Out-
(Waste Feedln, g/h),
Subscript i is for each component
Figure 2. Diagram for definition of blast furnace ORE and system ORE.
Table 4. Analytical Methods
Sample/Component
Analytical Method
Waste Oil
—POHCs
—Ultimate composition
(C. H. S. O. N, Cl)
heating value andHsO
Blast Furnace and Combustion
Process Emissions
—POHCs andPICs by VOST
—POHCs and PICs by MM5
—Chlorides
—Dioxins/dibenzofurans
—Paniculate matter
—Method 3 fixed gases
(O,. COj, CO, H)
Scrubber Water
—POHCs and PICs
—Dioxins/dibenzofura ns
Waste Oil Feed Tank Vent Gas
—POHCs
Extraction, followed by GC/MS
ASTM
Purge and trap, followed by GC/MS
Extraction, followed by GC/MS
Ion chromatography
High resolution GC/MS
EPA Methods
GC/TC
GC/MS
High resolution GC/MS
VOST sampling and analysis for
identification.
GC/FID for concentration
and semi-volatile compounds not found
in the waste fuel. Classification of these
compounds as PICs is avoided because
they may have originated in the blast air
or the iron ore/coke mixture, neither of
which was analyzed. Baseline emission
testing (no waste liquid feed) could not
be conducted without upsetting the
carbon and heat balances of the blast
furnace.
Carbon disulfide was found in signif-
icant concentration in the blast furnace
and stove off-gases and is typical of
incomplete combustion from operation at
reducing conditions. Concentrations
were not quantitated due to the water
solubility of the carbon disulfide that
limited sample recovery during the purge
trap and analytical method. Chlorome-
thane was also found in the gaseous
emissions but not detected in the waste
oil feed. No "nonfeed" compounds were
detected in the scrubber waters. Several
such compounds were found in the off-
gases during Run 2 (Table 6).
Storage Tank Vapor Phase
Integrated bag samples of vapors
exiting the waste feed storage tank
during truck off-loading were analyzed
on-site using GC/FID. Samples of the
vapors for GC/MS analysis were also
collected directly from the bag using a
VOST train.
An important factor limiting the
amount of information and the quality of
data that could be obtained from the vent
gas sampling effort was the high con-
centration of hydrocarbons in the vent
gas. The data gathered indicate that total
hydrocarbon (THC) concentration as
benzene ranged from 1 to 6 percent by
volume. This high THC concentration
resulted in condensation of organic
constituents on the interior of the Tedlar
bags before VOST sampling and the GC/
FID analysis.
No quantitative data could be obtained
from the GC/MS analysis because the
Tenax tubes were saturated with hydro-
carbons after sampling less than 0.1 scf
of vent gas. Organic compounds identi-
fied in the vent gas by GC/MS are listed
below:
Methylene chloride
1,1 -Dichloroethene
Chloroform
1,1,2-Trichloro-1,2,2-Trifluoroethane
2-Butanone
1,1,1-Trichloroethane
Trichloroethene
Benzene
5-methyl-1 hexanol
Tetrachloroethene
Toluene
Xylenes
All of the above compounds were alsc
found in varying quantities in the wastt
oil feed samples. Naphthalene was the
only waste oil feed POHC not detectec
in the storage tank vapor.
4
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Table 5.
ORE Results in Percent
Blast Furnace
Run 01
Run 02
Run 03
Mean
Run 01
Run 02
Run 03
Mean
For feed concentration > 1000 ppm:
1 , 1 -dichloroethene"
1 ,1 ,1 -trich/oroethane"
Trichloroethene"
Tetrachloroethene"
Toluene
m/p-XyleneD
o-Xy/eneb
Naphthalene0
99.968
--
99.998
99.997
99.987
99.940
99.993
>99.995
--
--
99.999
99.991
99.988
99.979
99.790
--
99964
99996
99.999
99.981
99.977
99.973
--
>99.972
--
>99.998
99.999
99.986
99968
99982
--
99.994
--
99.997
99.999
99.998
99.981
99.998
--
>99.998
--
--
99.998
99.999
99.999
99.996
99.977
>99.935
99.997
99.999
>99.999
99.960
99.993
--
>99.991
--
99.997
99.999
99.999
99.980
99.996
--
For feed concentration < WOO ppm
1,1 -dichloroethene"
Chloroform**
1 ,1 ,1 -trichloroethane"
Trichloroethene"
Naphthalene3
Methy/ene chloride"
Benzene"
"By VOST analysis.
"By MM5 analysis.
>99.700
>99 955
..
99860
>99.897
98886
>99 998
>99.997
>99.990
>99.968
99.143
>99.954
99973
--
__
99.640
>99.847
98.539
--
>99.890
>99.972
99.763
>99.904
98.856
--
99.876
99.944
__
99.993
99.823
99.954
99.995
99.967
99.998
--
99.941
99.853
>99.982
99.972
99.962
99.841
98.833
--
99.948
99.949
-_
99.977
99.868
99.547
Table 6. Non-Feed Compounds Detected at Outlet of Stoves—Run 02
Unknown0
5-Methyl-2-furancarboxatdehyde
1.1 -Dimethoxyheptane
Benzoic acid +1.1 -Di-methoxyoctanec
Methyl hexadecanoate
Methyloctadecenoate
Concentration
g/Sample
(Total)
180
200
230
250
1.970
2.060
ID
Confidence
Level'
1
2
2
2
2
2
"ID Confidence Levels. (II tentative, (2) confident, and (31 confirmed
^Apparent molecular weight is 142, probable empirical formula is Ca H-*,
^Concentration reported represents total of two co-eluting compounds
Dioxins/Dibenzofurans
All scrubber water, blast furnace off-
gas, and stove off-gas samples were
screened for dioxins and dibenzofurans
with high resolution GC/MS. Neither
class of compounds was detected at the
1-ppb detection limit for the aqueous
samples or 1 ppt detection limit for the
gas samples.
Conclusions
For reasons mentioned previously, the
ORE results for feed concentrations
below 1000 ppm as well as the results
for benzene and methylene chloride are
not reliable enough to draw conclusions
from them. Therefore, attention should
be focused on those POHCs having feed
concentrations greater than 1000 ppm.
Taking this into consideration, the LTV
Steel Blast Furnace shows considerable
potential as a hazardous waste
incinerator.
In looking at the blast furnace alone,
99.99% ORE was only consistently
attained in the cases of trichloroethene
and tetrachloroethene. But following
downstream combustion in the stove set,
DREs of 99.99% were consistently
measured for 1,1-dichloroethene,
toluene, and o-xylene in addition to the
trichloroethene and tetrachloroethene.
The analysis for PICs is of limited value
since there was no baseline emission
testing and neither the blast air nor the
iron ore/coke mixture was analyzed.
Based upon the analyses undertaken, it
would appear that carbon disulfide and
chloromethane are likely PICs.
A comparison of the volatile organic
emissions from the waste fuel storage
tank relative to the emissions of these
components from the combustor could
not be made since quantitation of tank
vapor emissions was not possible. How-
ever, with the exception of naphthalene,
all of the waste feed POHCs were
detected in the tank vapor phase.
Dioxins and dibenzofurans were not
present at detectable levels in the
effluent and emission streams.
Recommendations
In future tests, analysis of blast air and
the iron ore/coke mixture should be
undertaken to allow for more accurate
determination of PICs and DREs. Addi-
tionally, a test program is recommended
to determine venting rates of the indi-
vidual components of the tank vapor
phase in order to compare these rates
with those from the blast furnace
emissions.
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