United States
Environmental Protection
Agency
Industrial Environmental
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S2-84-072 May 1984
Project Summary
Assessment of Atmospheric
Emissions from Quenching of
Blast Furnace Slag with Blast
Furnace Slowdown Water
Gopal Annamraju, William Kemner, and P.J. Schworer
Use of blast furnace blowdown water
to quench hot blast furnace slag is a
possible alternative to the treatment and
disposal of this wastewater. Because
this alternative is not without possible
detrimental effects on air quality,
however, an environmental assessment
program was undertaken to evaluate
the air emissions arising from quench-
ing blast furnace slag with blowdown
water from a blast furnace scrubber
wastewater recirculating system.
Fifteen test runs were conducted at
two different slag temperatures, 1100
and 1500°F (593 and 816°C). Results
of this laboratory-scale assessment of
simulated blast furnace slag quenching
with mill service (baseline) water versus
blast furnace blowdown water indicated
that participate emissions increase at a
more pronounced rate with high slag
temperatures when blowdown water is
used, presumably because of its higher
total dissolved solids content. The
quenched slag was not considered
hazardous, based on the extractive
procedure (EP) toxicrty tests. Although
minor quantities of organic pollutants
evolve during quenching, the data
showed no relationship between these
pollutants and slag temperatures, slag
characteristics, or water quality. Also,
no correlation was found between
quench water quality or slag tempera-
ture and emissions of sulfur dioxide,
ammonia, and fluorides.
This Project Summary was devel-
oped by EPA's Industrial Environmental
Research Laboratory, Research Triangle
Park, NC. to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering
information at back).
Introduction
Blast furnace blowdown water can be
disposed of in several ways. One option is
to use the water for slag quenching.
Evaporation of blast furnace blowdown
water in slag quenching can eliminate
the discharge of this contaminated liquid
stream. Effluent limitation guidelines and
standards proposed by the U.S. Environ-
mental Protection Agency designate this
disposal method as Alternative I of the
Best Available Technology for handling
blast furnace wastewater. Because this
solution is not without possible detrimental
effects on air quality, however, several
approaches were considered for measuring
air emissions from slag quenching during
Phase 1. of this two-phase study. The
approach finally decided upon (because it
did not require the active cooperation and
participation of a steel plant) was to use a
specially designed container partially
filled with blast furnace slag and heated
in a custom-designed propane-fired
furnace. After the desired bulk slag
temperature was achieved, the test water
was continuously sprayed onto and
evaporated from the slag surface while
the slag temperature was maintained by
the furnace. Resulting emissions were
captured for analysis.
This laboratory method had the advan-
tage of allowing work to be performed
under controlled conditions, which
permitted accurate measurements to be
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made of the slag, the water, and the
emissions. It also allowed a comparison
of results between the use of mill service
water and blast furnace blowdown water
for quenching. The disadvantages were
that it was not possible to collect
emissions from the quenching of fresh
molten slag, no runoff water could be
generated because of the inherent design
of this approach, and water evaporated in
a semisealed container that probably
excluded potential reactions with air.
About 25 Ib (11.3 kg) of slag was poured
into containers at a blast furnace and
transported to the experimental furnace.
Blowdown water was obtained from
another blast furnace (with a scrubber
water system with a high recycle rate)
and transported to the laboratory in
Teflon-lined drums. Mill service water
was used as a baseline for comparison.
Fifteen test runs were conducted at two
different slag temperatures.
Equipment Design
Figure 1 shows the general arrange-
ment of the experimental setup. The slag
pots were designed to withstand the
severe thermal stress of being continu-
ously heated for 4 to 6 hours while the
slag was simultaneously quenched
inside the pot. They also had to withstand
the high temperatures of the molten slag.
Test Design
The main objectives of the test were to
correlate air emissions and slag charac-
teristics as a function of water quality and
slag temperature. For comparison, two
types of water were used: (1) typical mill
service water used for slag quenching,
and 2) blast furnace blowdown water
from a treatment system run at a high
recycle rate that meets Best Available
Technology (BAT) limitations with respect
to percentage recycle and blowdown rate
per ton of hot metal. The water was
analyzed for dissolved solids, priority
pollutants, trace metals, and organics.
Air Sampling Approach
The steam and air emissions generated
from slag quenching with the two
different types of water were sampled
and analyzed for various pollutant
species. The results of the mill service
water tests served as a baseline against
which to evaluate emissions from the use
of the contaminated blowdown water.
For most of the test runs, 15 liters of
quench water was added at a relatively
continuous rate throughout the test
period.
Testing for paniculate, sulfur dioxide,
metals, and organics was conducted with
__ Thermocouple
P"11
Stack -»JI Furnace
Stack
Test
Water
Insulated
Stainless Steel
Hood
•RA330
Slag Pot.
~Furnace
Shell
Propane
"•* k.
Air
Cast Refractory^
Refractory Brick Support •
Note: 1 in, = 2.54 cm.
Figure 1. General arrangement of the experimental setup (not to scale).
a Source Assessment Sampling System
(SASS) Train. Testing for hydrogen
sulfide, ammonia, fluoride, and cyanide
during a slag heat was conducted with
separate trains.
Test Results
The evaluation of the test data in terms
of water quality, slag temperature during
quenching, and slag characteristics is
presented under the following subcate-
gories: paniculate emissions, hydrogen
sulfide, sulfur dioxide, hydrogen cyanide,
hydrocarbons Ci to C? and C? to Ci6,
organic emissions, metals, and toxicity of
the quenched slag. All emissions except
permanent gases are expressed in terms
of milligrams or micrograms per liter of
water evaporated on the slag surface
during quenching. In all cases, the water
evaporated is the same as the water
applied.
Particulate Emissions
The level of paniculate emissions was
related to two conditions: the total
dissolved solids (TDS) content of the
quench water (450 mg/liter for the mill
service water versus 2491 mg/liter for
the blast furnace blowdown water) and
the temperature of the slag. Emissions
were:
Considerably less paniculate emis-
sions were generated during blast
furnace slag quenching with blast
furnace blowdown water than were
generated during coke quenching with
semidirty water. No firm conclusions can
be drawn, however, until data on slag
quenching emissions from actual produc-
tion facilities are available.
Type of water
TDS content,
mg/liter
Avg. slag
temp., °F(°C)
Particulates,
mg/liter
of H20 evap.
Mill service
Mill service
Blast furnace blowdown
Blast furnace blowdown
450
450
2491
2491
1125 (607)
1523 (828)
1116 (602)
1633 (889)
34.7
51.5
156.8
395.2
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Hydrogen Sulfide, Sulfur
Dioxide, Hydrogen Cyanide,
Ammonia, and Fluorides
Results of the samples collected are:
Hydrogen Sulfide (H2S)
Type of water
Mill service
Mill service
BF blowdown
BF blowdown
Slag
temperature,
°F (°C)
1142 (617)
1428 (776)
1117 (603)
1411 (766)
Slag
sulfur
content,
%
1.29
1.01
1.20
1.21
Slag
basicity
1.130
0.880
1.102
1.078
H2S,
mg/liter
23.2
Not detected
5.9
0.1
Several studies have been conducted
of HaS emissions during BF slag quenching.
The exact mechanism of H2S emissions is
not well understood, and no specific
attempt is made here to project the H2S
data generated during these tests.
Sulfur Dioxide (S02)
Type of water
Mill service
Mill service
BF blowdown
BF blowdown
Slag
temperature,
°F (°C)
1 1 20 (604)
1523 (828)
1116 (602)
1633 (889)
Slag
sulfur
content,
%
1.30
1.01
1.25
1.22
SO2
mg/liter
165
360
350
164
The SO2 content does not show any
relationship to water quality, slag sulfur
content, or quench temperature.
Hydrogen Cyanide (HCN)
Slag
temperature.
Type of water °F (°C)
Milt service 81 6 (436)
Mill service 1443 (784)
BF blowdown 1059 (571)
BF blowdown 1476(802)
Total cyanides
in water
mg/liter
0.03
0.03
0.12
0.12
HCN,
mg/liter
<0.0057
<0.012
0.0027
0.0008
The HCN data show a possible breakdown
of cyanide both at low- and high-
temperature slag quench.
Ammonia
Type of water
Mill service
Mill service
BF blowdown
BF blowdown
Slag
temperature,
°F (°C)
1040 (560)
1443 (784)
1099 (593)
1472 (800)
Ammonia (N)
in water,
mg/liter
<0.2
<0.2
33.3
33.3
Ammonia,
mg/liter
1.4
3.5
33.6
10.1
When blast furnace blowdown water is
used, the ammonia appears to break
down at higher quench temperatures.
Also, the ammonia emissions are higher
if the quench water contains higher
ammonia concentration.
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Fluorides
Type of water
Mill service
Mill service
BF blowdown
BF blowdown
Slag
temperature,
°F (°C)
816 (436)
1443 (784)
1059 (571)
1476 (802)
Fluorides
in water,
mg/liter
1.84
1.84
15.1
15.1
Fluorides,
mg/liter
35.3
238
32.4
157
The generation of fluorides is not de-
pendent on the concentration in the
quench water or the quench temperature.
Hydrocarbons: Ci to €7 and Cj
to Ci6
Grab samples were taken from each
test run and analyzed for hydrocarbons Ci
through C7. In a few cases, methane was
detected in the range of 1.2 to 23.7 ppm;
in the rest, it was below the detection
limit of 1 ppm. The presence of Czthrough
C? was generally undetectable or at very
minor levels.
Organics (C7 through Ci6) per liter of
water applied did not show any relation-
ship to either quench water type or slag
temperature.
Metals
The data for 40 elements were analyzed
by Inductively Coupled Argon Plasma
(ICAP) Optical Emission Spectrometry for
different test conditions. The highest
emission rates were found for aluminum,
calcium, potassium, sodium, silicon,
magnesium, uranium, and boron. In
general, the tendency was toward higher
emissions with higher slag temperatures,
which is in line with particulate emissions.
Metals such as arsenic, selenium, and
mercury (also determined separately) did
not show any relationship to slag
temperature or water type used during
quenching.
Organics
Only one priority pollutant (3.2 mg/liter
of phenol in the blast furnace blowdown
water) was detected in the quench water
samples. Selected runs, however, showed
the presence of the following in the air
emissions:
2-Chlorophenol 4 out of 5 samples
2,4-Dimethylphenol 2 out of 5 samples
Phenol 5 out of 5 samples
Fluoranthene 3 out of 5 samples
Naphthalene 4 out of 5 samples
Bis(2-ethylhexyl) 5 out of 5 samples
phthalate
Butybenzyl 5 out of 5 samples
phthalate
Di-n-butylphthalate 5 out of 5 samples
Diethyl phthalate 3 out of 5 samples
Acenaphthylene 3 out of 5 samples
Anthracene and/or 4 out of 5 samples
phenanthrene
Fluorene 3 out of 5 samples
Pyrene 4 out of 5 samples
The levels for phenol, 2-chlorophenol,
2,4-dimethylphenol, and phthalates were
relatively high compared with other
organic substances, and they bore no
relationship to quench water quality or
slag temperature. The following are some
of the possible explanations for the
presence of organics in the air samples.
The formation of organics may result
from slag/water reactions at high
temperature in an oxygen-deficient
atmosphere. It is not uncommon for some
unburnt coke to be present in slag, which
might contribute the required carbon.
Also, minute quantities of organics in the
quench water below detection limits
might have shown up in the air samples.
The presence of phthalates is presumably
due to binders in the sampling train filter.
Slag Toxicity Data
Eight metals tested for EP toxicity
under each quenching condition were
well below allowable concentrations. The
reactivity tests for cyanide showed
negative results; however, three of the
four sulfide reactivity tests showed
positive results.
Conclusions
The laboratory-scale assessment of
simulated blast furnace slag quenching
(using mill service water versus blast
furnace blowdown water) produced the
following major findings and conclusions:
1) The level of particulate emissions is
higher when the blowdown water
(with a high total dissolved solids
content) is used for quenching, and
the level of these emissions increases
greatly when the temperature of the
slag quenched is high. The propor-
tional increase at high temperatures
is not nearly as great when mill
service water is used.
2) Particulate emissions from slag
quenching with blast furnace blow-
down water are much lower than
those produced by coke quenching
with semidirty water with a similar
total dissolved solids content.
3) Based on this laboratory-scale ^
evaluation, the particulate emissions ^
generated by high-temperature slag
quenching with blast furnace blow-
down water are significantly lower
than uncontrolled blast furnace
cast house emissions.
4) Emissions of metals increase with
high-temperature slag quenching.
5) There is no EP toxicity connected
with slag quenching, with either
clean or blast furnace blowdown
water.
6) No specific relationship was found
between organic pollutants and the
use of blowdown water or slag
temperature during quenching.
7) No correlation was found between
quench water quality or slag tem-
perature and emissions of SO2,
ammonia, and fluoride. Cyanides
appeared to break down at both low-
and high-temperature slag quench.
Recommendations
1. Similar tests, carried out with
spiked quench water samples,
would help to better understand the
behavior of toxic organic pollutants
during quenching.
2. Laboratory scale tests, similar to
those conducted during this project, ^
would help determine the feasibility fl
of using coke plant wastewater as a
quenching medium for BF slag
quenching.
3. Tests conducted at a plant site that
practices hard slag quenching with
mill water, blast furnace blowdown
water, and (if possible) coke plant
wastewater would help verify the
test data and findings of this project.
4
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G. Annamraju, W. Kemner. and P. J. Schworer are with PEDCo Environmental.
Inc., Cincinnati, OH 45246.
Robert C. McCrillis is the EPA Project Officer (see below).
The complete report, entitled "Assessment of Atmospheric Emissions from
Quenching of Blast Furnace Slag with Blast Furnace Slowdown Water, "(Order
No. PB84-172 493; Cost: $11.50, 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
-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
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U.S. GOVERNMENT PRINTING OFFICE: 1984-759-102/948
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