still for framstellning of pure alumina by the effect of acid on aluminium minerals - other elements

摘要

A method of obtaining alumina of high purity from aluminous mineral containing impurities by attacking the mineral with a sulphuric acid liquor and separating the resulting liquor from a residue which remains after the attack, the steps of (a) mixing the resulting liquor with a liquor containing HCl and H2SO4, (b) introducing HCl gas into the mixture, (c) cooling the mixture from step (b) to precipitate hydrated aluminum chlorosulphate crystals having the formula AlSO4Cl.6-7H2O, (d) separating the hydrated crystals of hydrated aluminum chlorosulphate from the mother liquor, (e) heating the separated crystals to a temperature that does not exceed 600 DEG C. to yield a mixture of aluminum sulphates and hydrochloric gases, (f) thermally decomposing the aluminum sulphates to yield alumina of high purity and sulphuric gases, (g) degassing the mother liquor of step (c) to yield HCl gas, (h) concentrating the mother liquor from step (f), (i) freeing the concentrate from impurities, and (j) recycling the mother liquor from step (h) to the attack on the aluminous mineral.