GB846468A - Treatment of metallic ores - Google Patents

Abstract

Compositions containing two or more metallic oxides or oxidic metallic components are contacted with a fused alkali-metal hydroxide at such a temperature that a liquid phase and a solid phase are formed, the liquid alkali metal hydroxide being enriched with respect to one of the metal values, and the solid phase being enriched with respect to another. The two phases are then separated, for example by filtering, or decanting. The separated liquid phase may then be cooled and leached with a solvent for the alkali-metal hydroxide, such as water, leaving the metallic oxide constituent as a solid. The leach solution, consisting of the alkali metal hydroxide, after settling of trace impurities, may be evaporated and recycled to the fusion step. Sodium, potassium, lithium and cesium hydroxides are referred to. Preferably the metallic oxide composition constitutes 1%-50% by weight of the mixture with the alkali-metal hydroxide. In examples, iron oxide-titanium oxide ores such as ilmenite are treated with fused caustic soda, the titanium entering the liquid phase and the iron remaining as the solid. Sodium chloride depresses the solubility of the titanium oxide and must therefore be avoided. However, the titanium dioxide may be recovered from the liquid phase after separation by adding sodium chloride to precipitate the titanium dioxide. The lower the temperature worked at, the greater is the titanium-iron ratio in the liquid phase. Any iron oxide suspended in the liquid phase may be removed by filtering through a sintered stainless steel filter with a pore size of about 5 microns. The liquid phase may be cooled to obtain crystals containing most of the titanium, either as titanium dioxide or a titanate, which are removed from the melt. Other ores which may be treated by the process of the invention include tungsten-iron ores, in which the tungsten enters the liquid phase, chromite-iron ores with the chromium oxidised to the hexavalent state, in which the chromium enters the liquid phase, and vanadium-uranium ores such as carnotite, in which the vanadium enters the liquid phase.