Patent ID: 7097816

Claim:
A method of producing ferrous sulfate heptahydrate from ferrous sulfate monohydrate, comprising the steps of: reacting a pickling solution containing ferrous chloride (FeCl 2 ), hydrochloric acid (HCl) and water (H 2 O) in a precipitating reactor with excess of sulfuric acid (H 2 SO 4 ) to form ferrous sulfate monohydrate (FeSO 4 ) and hydrochloric acid; separating the ferrous sulfate monohydrate and hydrochloric acid; dehumidifying the ferrous sulfate monohydrate; feeding the ferrous sulfate monohydrate to a crystallization reactor for converting the ferrous sulfate monohydrate in the presence of water into ferrous sulfate heptahydrate as crystallized product at a retention time between four and eighteen hours at a temperature from 160° C. to 200° C.; and isolating water from the ferrous sulfate heptahydrate.