The layer of scale adhering to the hot-rolled strip in Cold Rolling Mill No. 1 is removed in a sulfuric-acid solution during the so-called pickling process. The resulting ferrous-sulfate solution is vacuum-cooled in a crystallisation vat. Ferrous-sulfate crystals are formed during this cooling process. The resulting pasty mixture is poured into a concentrator, which is a sedimentation container where the ferrous-sulphate crystals can separate from the rest of the mixture. The ferrous sulfate is then further separated in centrifuges and placed in storage containers. The remaining pickling liquor is recycled into the pickling bath.

Waste-water treatment
Phosphate elimination
Raw material for high-quality pigments
Cement-making industry (chromate reduction)