METHOD OF COMPLEX PROCESSING OF BAUXITES Russian patent published in 2005 - IPC

FIELD: reworking of low-quality bauxites at high content of silica, iron, sulfur and carbonates into alumina by combined Bayer-sintering scheme.

SUBSTANCE: proposed method includes grinding bauxite in Bayer branch, concentration of it by removal of kaolinite and iron sands, leaching-out, thickening of pulp thus obtained, separation of aluminate solution from red mud, filtration of red mud immediately after thickening, hydrochemical processing of part of said mud for obtaining sodium hydroaluminate, decomposition of aluminate solution, calcination of aluminum hydroxide, evaporation of mother liquer at separation of circulating soda, organic admixtures and sulfates, thus obtaining circulating solution which is subjected to thorough evaporation for obtaining sodium hydroaluminate which is used in decomposition. Gallium is obtained from mother liquer after crystallization of sodium hydroaluminate. After separation of gallium, high-modulus solution is delivered for hydrochemical processing. Proposed method includes also preparation of charge in sintering branch from red mud at addition of alkaline, bauxite at silicon modulus below Bayer modulus of solid phase of separated kaolinite fraction, part of separated pulp after separation of iron sands, sintering of mud charge, leaching-out of sinter at simultaneous washing-out and separation of mud, delivery of aluminate solution to Bayer branch for leaching-out; proportioning of bauxite is performed for obtaining the caustic modulus in sinter not above 1.2.

EFFECT: increased yield of alumina; increased temperature field of sintering; increased causticizing ability of sintering branch; increased size of aluminum hydroxide; increased extraction of gallium; reduced losses of alkaline.

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