PRODUCTION OF ALUMINA FROM LOW-GRADE ALUMINIUM-BEARING STOCK Russian patent published in 2015 - IPC C01F7/20 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy. Proposed process comprises steps that follow. Aluminium-bearing stock is processed by hydrochloric acid to get chloride pulp. The latter is separated to extract chloride solution. Aluminium chloride is salted out from chloride solution by calcium chloride. Aluminium chloride is thermally decomposed to get alumina. Chloride pump is neutralized by calcium oxide to pH of 1.6-2.2. After salting out of aluminium chloride, mother solution is subjected to stepwise stripping with selective crystallization of alkali metal chlorides and extraction of calcium chloride as crystals and/or concentrated water solution. Note here that a portion of calcium chloride is returned for salting out of aluminium chloride.

EFFECT: higher quality of alumina, decreased power consumption.

5 cl, 1 dwg, 1 tbl