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

A process for obtaining pure alumina comprising the combination of chlorosulphuric attack of calcined aluminous ores containing impurities, followed by concentration of the liquor obtained after the attack and separation of the sterile material, sulphuric acid treatment of the concentrated liquor followed by chlorination to precipitate almost all the hexahydrated aluminum chloride, separation of the precipitate of hexahydrated aluminum chloride and of the chlorosulphuric mother liquor charged with impurities, pyrohydrolysis of the precipitate to give the desired pure alumina with recycling of released hydrochloric acid, degassing of the chlorosulphuric liquor of impurities with recycling of the gaseous HCl for chlorination, yielding a sulphuric liquor of impurities, finally the elimination of the impurities present in this latter liquor in the form of a sulphuric precipitation by concentration in the presence of potassium ions.