Continuous process for obtaining pure aluminium oxide from an acid liquor originating from the chloro-sulfuric leaching of an aluminous mineral, and the purification of the liquor separated from the aluminium oxide

摘要

New continuous process for obtaining pure alumina comprising novel combination, chlorosulphuric attack (B) of calcined aluminous minerals containing impurities, followed by concentration of the liquor obtained after etching and separation of sterile (S _2), sulfuric treatment of the concentrated liquor, then its chlorination (L) causing precipitation of substantially all of the aluminum chloride hexahydrate, separating the precipitate of aluminum chloride hexahydrate (Se) and the mother liquor chlorosulfuric ( L6) loaded with impurities, the pyrohydrolysis of the precipitate gave pure alumina sought with recycling of hydrochloric acid, the degassing (K) of the chlorosulphuric liquor of impurities with recycling of the gaseous HCl in chlorination (G) and obtaining a sulfuric impurities liquor (L 11), and finally the removal of the impurities present in the latter liquor in the form of a concentrate by sulfuric precipitation ion (L) in the presence of potassium ions.