METHOD OF CONVERSION OF BAUXITES INTO ALUMINA Russian patent published in 2004 - IPC

FIELD: non-ferrous metallurgy.

SUBSTANCE: the invention is dealt with field of non-ferrous metallurgy, in particular, with technology of production of alumina from bauxites. The offered method includes in Bayer's branches a milling of a bauxite in a recycling solution, a lixiviation, thickening with production of an aluminate solution and a red slime, a red slime washing, decomposition of the aluminate solution with production of aluminum hydroxide and a mother liquor, evaporation of the mother liquor and production of the recycling solution, calcination of aluminum hydroxide with production of alumina. In the branch of sintering they exercise preparation of a charge, sintering of a charge, a lixiviation of the produced cake with production of the aluminate solution containing silica and the red slime, a desiliconization of the aluminate solution with production of a white slime and the desiliconized aluminate solution, its feeding in Bayer's branch for decomposition, reprocessing of the white slime of the branch of sintering. The charge supplied for sintering is prepared by mixing of the red slime, the bauxite and the recycling solution with a proportioning of a free alkali in the recycling solution to reach a molar ratio of Na₂O / (Al₂O₃+SiO₂) = l - l.2 and to reach a molar ratio_{Al2O3/Fe2Оз = 0.33-0.5, and sintering is exercised at the temperature of 350-450°С. Reprocessing of a white slime of the branch of sintering is exercised by its mixing with a limestone, sintering at the temperature of 1200-1350°С, by lixiviation of the cake with production of bicalcium silicate and the recycling solution with supply of the latter for a desiliconization. The red slime produced after the lixiviation of the cake is directed for extraction of iron, titanium and РЗМ. The technical result is saving of bauxite, alkali, fuel.}

EFFECT: the invention allows to save bauxite, alkali and fuel.

3 cl, 1 tbl, 2 ex