Method of producing pure alumina from alunite
AssigneeFinancial Mining - Industrial and Shipping Corporation
InventorJason Svoronos
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Abstract
Pure alumina (Al.sub.2 O.sub.3) is recovered from alunite (Al.sub.2 (SO.sub.4).sub.3.K.sub.2 SO.sub.4.4 Al (OH).sub.3) which is found mixed with various impurities by first calcinating the alunite in the presence of a chloride to produce impure Al.sub.2 O.sub.3 and other biproducts, and the impure Al.sub.2 O.sub.3 is then contacted with concentrated HCl to produce, after concentration and crystallization, crystals of AlCl.sub.3.6H.sub.2 O. These crystals are then calcinated to yield highly concentrated HCl and pure alumina.
Claims7
A method of producing purified alumina from impure alunite consisting of:
- (a) calcinating the impure alunite in the presence of a chloride selected from the group consisting of potassium chloride, sodium chloride, and mixtures thereof at a temperature of between about 500.degree. C. to 590.degree. C. to form impure alumina (Al.sub.2 O.sub.3), sulfates, dilute HCl, and other byproducts;
- (b) removing the produced sulfates from the calcination products of (a) by extraction with hot water;
- (c) contacting the impure alumina produced in (a) with HCl having a concentration of 30% or more and at a temperature of between room temperature and about 100.degree. C. to produce an aqueous solution of aluminum chloride;
- (d) recovering the aluminum chloride from the solution of (c) by concentrating to produce crystals of AlCl.sub.3 .times.6H.sub.2 O;
- and
- (e) calcinating the aluminum chloride from (d) to yield pure alumina and concentrated HCl.
Dependencies are inferred from the claim text.