METHOD OF PRODUCING ALUMINA Russian patent published in 2015 - IPC C01F7/20 C01F7/22 

FIELD: agriculture.

SUBSTANCE: invention relates to acid methods of production alumina and can be used in processing of low grade aluminium-containing material. The method of production alumina comprises roasting the raw material, its treatment with hydrochloric acid, salting out aluminium chloride by saturating the clarified chloride solution with gaseous hydrogen chloride, calcination of aluminium chloride to obtain aluminium oxide and pyrohydrolysis of mother liquor with return of the hydrogen chloride on the acid treatment and salting out step. Aluminium chloride precipitated in the salting-out process is treated with aqueous ammonia, the resulting precipitate is fed to calcination, and the solution of ammonium chloride is mixed with an aluminium-containing raw material before its roasting or during roasting. Ammonia emitted during roasting is dissolved in water, the aqueous ammonia thus obtained is fed to treatment with aluminium chloride. Ammonium chloride solution before mixing with the aluminium-containing raw material may be subjected to staged evaporation under repeated use of heating steam. Ammonium chloride emitted by evaporation may be mixed with the aluminium-containing raw material.

EFFECT: invention provides improvement of quality of alumina and reduction of energy consumption.

1 dwg, 1 tbl