Production of iron sulfate monohydrate

The process for producing high purity crystals of ferrous sulfate monohydrate from a purified solution that is essentially saturated with ferrous sulfate at temperatures of 50.degree. to 80.degree. C. which comprises the steps of:

• a. cooling the solution to a temperature below about 50.degree. C. to precipitate crystals of ferrous sulfate heptahydrate,
• b. separating the crystals of ferrous sulfate heptahydrate from the solution at a temperature below about 50.degree. C.,
• c. pulping the crystals of ferrous sulfate heptahydrate in a hot purified aqueous solution that is essentially saturated with ferrous sulfate to produce a high density slurry of crystals,
• d. heating the slurry of crystals to a temperature of from about 56.5.degree. to about 64.8.degree. C to dehydrate a fraction of the crystals from FeSO.sub.4.7H.sub.2 O to FeSO.sub.4.4H.sub.2 O,
• e. separating the crystals of FeSO.sub.4.4H.sub.2 O from the slurry,
• f. pulping the crystals of FeSO.sub.4.4H.sub.2 O in a hot purified aqueous solution that is essentially saturated with ferrous sulfate to produce a second high density slurry of crystals,
• g. heating the second slurry with hot gases to a temperature above 65.degree. C. to evaporate the water and to produce dry solids that are essentially pure crystals of ferrous sulfate monohydrate, and
• h. collecting the crystals of ferrous sulfate monohydrate as product of the process.