METHOD OF ISOLATION OF ALUMINA AND SILICA Russian patent published in 2001 - IPC

FIELD: chemical industry, more particularly isolation of essentially pure alumina and silica from stock comprising alumosilicates. SUBSTANCE: method comprises (i)heating alumosilicate with hydrated CaCl₂ to prepare calcium alumosilicate and calcium aluminate products wherein CaCl₂ is predominantly free from MgCl₂; (ii) leaching HCl products to form solution containing AlCl₃; and CaCl₂ and insoluble silica; (iii) isolating insoluble silica from solution and (iv) crystallizing AlCl₂ from solution and isolating alumina from crystallized AlCl₃. Method further comprises removing predominantly MgCl₂ from CaCl₂ solution in stage (iv) and recycling CaCl₂ solution for use in stage (i). Invention makes it possible to isolate essentially pure alumina and silica. EFFECT: more efficient isolation method. 13 cl, 1 dwg, 3 ex