GB980864A - Improved process for the beneficiation of ores - Google Patents

Abstract

The iron content of an ore containing compounds of iron and other metals, particularly ilmenite, is decreased by heating the ore in the presence of a reducing agent to bring about the formation of metallic iron, but without bringing the iron into the form of a molten mass or reducing the other metal compounds present in the ore, submerging the reduced ore in an aqueous medium and maintaining it in agitated suspension therein to effect physical separation of metallic iron from the remaining metal compounds whilst contacting it with an oxidizing gas to effect preferential oxidation of the element iron and effecting separation between the resulting iron-oxidation product and the remaining metal compounds. Reducing agents specified are coal, coke, coal char, charcoal and carbonaceous reducing gases, and oxidizing gases which may be used include a mixture of air or oxygen and carbon dioxide, sulphur dioxide and nitrous oxide, the last two of which may be used either alone or in admixture with one or more of air, oxygen and carbon dioxide. The reduced ore is advantageously separated from gangue and unburnt reducing agent prior to the oxidation step. The oxidation reaction may be catalysed by the presence of sulphur or its oxides, sulphides, oxidizing agents, cations, e.g. ammonium, alkali metal, copper and cobalt ions, and inorganic and organic anions, e.g. acetate, chloride, sulphate, nitrate, fluoride and thionate ions. The oxidation may be carried out at atmospheric pressure and a temperature of 60 DEG to 80 DEG C., or at super-atmospheric pressure and an increased temperature, e.g. 100 p.s.i.g. and 150 DEG to 170 DEG C. The pH of the aqueous medium during the oxidation step is advantageously at least 4 and less than 7. The examples relate to the removal of iron from ilmenite and from a gold-containing ore. Specification 547,898 is referred to.