TREATMENT OF STEEL PLANT BLAST FURNACE EFFLUENT
USING PHYSICAL/CHEMICAL TECHNIQUES
Richard Osantowski, Research Engineer
Rexnord Inc.,
Environmental Research Center
Mdwaukee, Wisconsin 53214
Robert Hendriks. Project Officer
U.S. Environmental Protection Agency
Industrial Environmental Research Laboratory
Research Triangle Park, North Carolina 27711
The iron making blast furnace is a major source of water pollution in an integrated steel
plant. As much as 10,000 liters of water per megagram of iron (2400 gal/ton) is used to
remove large quantities of entrained dust in the blast furnace off-gas to render it usable as
a CO rich fuel within the steel plant. In addition to solids material, the gas wash water
also picks up dissolved organics and inorganics which are considered water pollutants and
require treatment before discharge. Recent advances in water recycle techniques have enabled
almost complete recycle of the blast furnace water, so that only a blowdown stream of 210
to 420 liter/Mg (50 to 100 gal/ton) is required from the blast furnace recycle system.
However, this stream contains residual amounts of suspended solids, phenols, ammonia,
cyanide, fluoride, and other pollutants which must be treated before discharge to a receiving body.
The U.S. Environmental Protection Agency (EPA) is developing best avadable technology
(BAT) economically achievable effluent limitation guidelines for steel plants which wdl
include the requirement of advanced treatment of blowdown streams. As part of an overall
effort to develop background technical data on blast furnace treatment, a number of
physical/chemical treatment schemes applicable to blast furnace wastewater were evaluated
on a pdot scale. The in-depth pilot plant study was performed using mobde treatment
facdities designed specifically for evaluation of treatment of blast furnace, coke plant, and
other steel plant wastewaters. Schematic representations of the mobde testing systems are
shown in Figure 1 and 2. Trader No. 1 housed the alkaline chlorination, chemical treatment,
magnetic filtration and dual media filtration systems. The ozonator, activated carbon, and
reverse osmosis technologies were in trader No. 2. The mobde system contained a high
degree of automation which greatly assisted the operators during the study. All of the
treatment technologies were designed to treat a nominal flow of 18.9 liter/min (5 gpm).
Figure   I.  Steel  plant  mobile  treatment system.
Trailer Na 1.
Figure  2.  Steel  plant  mobile  treatment system.
Trailer Na 2.
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