PURPOSE: To enable mass-production of high-purity iron oxide powder with simple process at a low cost, by adding sulfur to iron sulfate powder as a heat source and subjecting the powder to thermal decomposition in a roasting furnace.
CONSTITUTION: The surface of iron sulfate powder is attached or coated with sulfur as a heat source and the powder is subjected to uniform thermal decomposition in a roasting furnace (e.g. fluidized roasting furnace) at 550W800°C while suppressing the decomposition reaction of MnSO4 and keeping the SO2 concentration in the generated gas at a specific level (e.g. ≥15%) to convert the iron sulfate powder to Fe2O3. The roasted product is charged into an aqueous solution to extract and remove the impurities and obtain high-purity iron oxide powder.
SAHO YOSHITAKE
ISHITA TSUTOMU
KITAZAWA TADAO
KOWA SEIKO