PROCESS FOR PRODUCING ALUM EARTH FROM BAUXITE CONTAINING GIBBSITE

摘要

Process for the production of alumina from "gibbsitic" bauxites. The process comprises mixing "gibbsitic" bauxites with sodium hydroxide-sodium aluminate digestion liquor, digestion between 100 and 180 degree C, dilution of the suspension, separation of the red sludge, precipitation of aluminium hydroxide and calcination, characterised by control of the process in which the concentration of reactive hydroxides in the liquid phase leaving the reactor, defined by the formula IMAGE is maintained below 6 g/l, preferably between 0 and 2 g/l. Desirably this control is achieved by controlling the bauxite/digestion liquor ratio.