METHOD OF ALUMINUM OXIDE PRODUCTION Russian patent published in 2005 - IPC

FIELD: nonferrous metallurgy; processing of the bauxites.

SUBSTANCE: the invention is pertaining to the field of the nonferrous metallurgy, in particular, to processing of the bauxites consisting mainly of a trihydrate of aluminum oxide with a low share of silicon oxide. The method provides for mixture of bauxite with a part of the recirculating alkali-aluminate solution and its leaching in two phases. At the first phase a leaching of the produced suspension is conducted at the temperature of 95-110°С and a concentrations of caustic alkali of 200-260 g/l, with a batching of bauxite by 20-70 % higher than it is required for production of an equilibrium caustic modulus in the given conditions of the leaching. The slime is separated from aluminate solution, mixed with bauxite and the remained part of the recirculating solution and the produced suspension is leached at the temperature of 150-250°С and the concentrations of caustic alkali of 160-220 g/l at the second phase with batching of the recirculating solution ensuring obtaining of the caustic modulus in the final aluminate solution by 0.03-0.1 unities higher its equilibrium level in the given conditions of the leaching. The slime is separated from the aluminate solution, the slime is flushed, the aluminate solution is subjected to decomposing with production of aluminum hydroxide and a mother liquor. The mother liquor is evaporated and produce circulating alkali-aluminate solution. The invention allows increase efficiency of Bayer process.

EFFECT: invention allows increase efficiency of Bayer process.