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US 5,312,602 AGranted
Method for purifying iron oxide
AssigneeA/S Sydvaranger
InventorsKarl J. V. Svensson, Bo H. Zander
Life of this patent
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Abstract
A method is described for purifying iron oxide, for example, in the form of magnetite or hematite slime, which preferably contains quartz as the impurity. The method comprises calcinating the iron oxide together with alkali carbonate and thereafter leaching with a weak aqueous solution of an acid or a mixture of acids.
Claims8
A method for purifying iron oxide from a quartz-containing iron ore, to an SiO.sub.2 content that does not exceed 0.03% by weight, comprising:
- (a) contacting a finely divided quartz-containing iron oxide ore with an alkali carbonate in an amount sufficient to obtain an alkali oxide/(SiO.sub.2 +Al.sub.2 O.sub.3) mole ratio of about 0.5-2.0;
- (b) calcinating said quartz-containing iron oxide ore with said alkali carbonate at a temperature of about 850.degree.-1000.degree. C. for a time sufficient to melt the alkali carbonate;
- (c) leaching said calcinated ore at room temperature with a weak aqueous solution of at least one acid selected from the group consisting of hydrochloric acid, hydrofluoric acid, sulfuric acid and nitric acid until the SiO.sub.2 content of the ore is less than 0.03% by weight.
Dependencies are inferred from the claim text.