Patent ID: 9517944
Filing Date: 2016-12-13
CPC Classification: C01F,C01G,C01P,C22B,Y02P

Claim Text:
1. A method for producing alumina, comprising: mixing and roasting an aluminum-containing raw material with an ammonium chloride solution to produce a roasted raw material wherein said roasted raw material undergoes partial thermal activation and the ammonium chloride undergoes decomposition; dissolving the ammonia released during the roasting in water to form aqueous ammonia; treating said roasted raw material with hydrochloric acid to produce a slurry comprising a solid phase and a clarified chloride solution; salting out aluminum chloride by saturating the clarified chloride solution with gaseous hydrogen chloride to produce a mother liquor and aluminum chloride hexahydrate in crystalline form; subjecting the aluminum choride hexahydrate in crystalline form to treatment by the aqueous ammonia previously produced, to forming boehmite and an ammonium chloride solution; calcining the boehmite to produce aluminum oxide; and pyrohydrolyzing the mother liquor to form hematite and hydrochloric acid, wherein the hydrochloric acid is used in the treating of the roasted raw material step and the salting out aluminum chloride step.