Copperas (FeSO4 . 7H2O) is crystallized to regenerate spent liquors from
the sulphuric acid pickling in the steel industry. In the TiO2 industry the
crystallization is needed to keep a low level of ferrous sulphate in the
recirculated process liquors. The photos below show these applications. The
last photo is a DT crystallizer for Copperas in the TiO2 industry, the other
two are presenting applications in the Pickling Bath industry.