A method for the treatment of a mixture of aluminum oxide trihydrate and aluminum oxide mono hydrate bauxites containing

摘要

Treatment process for the alkaline attack according to the bayer process of the bauxite is mixed, or bauxite containing alumina trihydrate, also containing alumina in the monohydrate state in the proportion by weight of at least 5% of the total quantity of alumina in the bauxite. It is used for the liquors at high concentration of caustic soda in the 2 attacks at low and high temperature of the bauxite, the liquor of 1ère attack being constituted by the mixture of an aliquot of the spent liquor with the liquor simply decanted from the attack operation at high temperature of the residues of 1ère attack containing alumina monohydrate. On the basis of the supersaturated liquor from 1ère attack, after decantation, filtration and dilution, in order to reduce its concentration of caustic soda, it is precipitated by the decomposition in the presence of a trihydrate seed of high purity, with a high productivity and a yield of extraction of the soluble alumina greater than 95%.