A method for the preparation of alumina

Abstract

A method for the preparation of alumina from alunite, the method comprising the steps of: (i) attrition of an alunite material; (ii) washing and settling the alunite material to reduce sodium content; (iii) acid leaching and roasting the Na-reduced alunite material; (iv) passing the product of the acid leach and roast step (iii) to a water leaching step to produce a liquid product comprising aluminium and potassium; (v) subjecting the liquid product of step (iv) to a precipitation step to precipitate an aluminium salt; (vi) purifying the aluminium salt; and (vii) subjecting the purified aluminium salt to a calcination step to produce alumina.

Dependencies are inferred from the claim text.