| 摘要 |
Process for the treatment, by alkaline attack according to the Bayer process, of mixed bauxite or alumina trihydrate bauxite also containing alumina in the monohydrate state in the proportion by weight of at least 5% of the total amount of alumina in the bauxite. Liquors containing a high concentration of caustic soda are used during the 2 low- and high-temperature attacks on the bauxite, the liquor of the 1st attack consisting of the mixture of an aliquot of decomposed liquor with the liquor, separated simply by settling, resulting from the attack at high temperature on residues of the 1st attack containing alumina monohydrate. From the supersaturated liquor resulting from the 1st attack, after separation by settling, filtration and dilution in order to reduce caustic soda concentration, the precipitation is carried out, by decomposition in the presence of an initiator, of a high purity trihydrate with a high productivity and an extraction yield of dissolvable alumina greater than 95%. <IMAGE>
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