Abstract: The invention relates to acid methods for producing alumina for use in processing low-grade aluminum-containing raw materials. The method provides treating aluminum-containing raw materials with hydrochloric acid, crystallizing aluminum chloride hexahydrate by evaporating the supernatant chloride solution, and thermally decomposing the aluminum chloride hexahydrate to form aluminum. Crystallization is carried out with the addition of calcium chloride.

Abstract: The invention relates to metallurgy, particularly to acid methods or producing alumina, and can be used in processing low-grade aluminum-containing raw materials. The method for producing alumina comprises treating aluminum-containing raw materials with hydrochloric acid, crystallizing aluminum chloride hexahydrate by means of evaporating the supernatant chloride solution, and thermally decomposing the to form alumina. In order to increase the quality of the alumina and decrease energy consumption, crystallization is carried out with the addition of calcium chloride, wherein the ratio of the total mass of calcium chloride to the calculated mass of alumina in the supernatant solution equals 2-4, in the presence of aluminum chloride hexahydrate seed crystals having an average particle size of 250-500 microns.