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Effluent handling is a major issue for steelmakers. In several areas of the steel plant, fumes,
water and by-products need to be treated so that they meet strict emission
levels. Lhoist's steel and environmental specialists will work hand in hand with you to
develop products which can help you to comply with this legislation effectively
and economically.
Treatment
of fumes
The very low
emission levels which are being imposed for flue-gases, as well as for dioxins and furans, call for a highly effective
reagent, and a process that can easily be incorporated into existing installations.
For flus-gas treatment in a dry
sorption system, SO2 and other acid gases can be neutralised
with hydrated lime. Sorbacal® SP is a lime with a high porous volume, which has been especially developed to
increase the efficiency of dry flue-gas cleaning systems.
To content with dioxins and furans, Lhoist delivers tailor-made
mixtures of lime with activated carbon, lignite coke or bentonite, which that combine
the neutralising effect of lime and with the micro-pollutant capturing power of
the additives. This formula means you avoid the negative side-effects associated
with injection of pure activated carbon.
Scrubbing fumes is an alternative process to dry sorption. The resulting acidic
waters can be neutralised with lime.
Neutralisation of acidic
water
Acidic
water resulting from pickling, rinsing and fume scrubbing is neutralised by
adding lime milk, in order to reach the appropriate pH level and precipitate heavy
metals. After sedimentation, this water can be recycled or returned to the
sewage system.
Stabilisation of sludge
Water
treatment generates a certain amount of sludge. Adding lime milk before
filtration makes this sludge easier to filter, thanks to the flocculating effect of lime.
Converter fumes containing dust are usually washed. The sludge resulting from
the settling of these wash waters can be treated with lime to recycle them in
the form of briquettes for the sinter plant, as the additional calcium adds
value to the sintering process.
Even if the sludge cannot be recycled, its dehydration and solidification with
milled quicklime make it easier to handle, transport and store.
By-Products
We have a lot
of experience in the potential markets for lime by-products. We can take over
inertisation and landfilling at a competitive price. We can deal with the legal
aspects and ensure that the process complies with all the relevant local regulations.
We can also help you to eliminate or market certain steel by-products. For instance,
non-recyclable dust collected in the furnace extraction system can be inertised
and given a new value as strengthening material in mines.
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