GB785602A - Improvements in or relating to extraction of uranium from its ores - Google Patents

Abstract

Uranium is extracted from phosphatic ores containing it by treating the ore with sulphuric acid of substantially 1.84 specific gravity, to decompose phosphates present and form a system comprising a liquid sulphuric acidphosphoric acid phase and a solid phase containing substantially all of the uranium from the ore, and thereafter separating the solid phase from the liquid phase and working it up to recover uranium. The solids are preferably separated from the liquid by centrifugal means and afterwards taken up with water to dissolve the uranium and the solution treated with a soluble barium salt and filtered. The remaining solution is then treated with sodium hydroxide, ammonia or magnesium oxide to precipitate metals, including uranium, as hydroxides. Thereafter the separated and washed hydroxides are brought into nitric acid solution, from which the uranium may be extracted by means of diethyl ether or other organic solvent. According to an example, monazite was treated with sulphuric acid and heated to 220 DEG C. for two hours, and after cooling the solids were separated from the liquid. The solids were taken up with water and the resulting solution after dilution, was treated with gelatin and barium nitrate, the barium sulphate so formed acting as a collector for the mesothorium and the gelatin floculating the silica present. The filtrate was treated with caustic soda and the precipitate obtained after washing was taken up in nitric acid leaving an insoluble residue of thorium and ceric phosphates. The insoluble residue was, after separation, boiled with caustic soda, filtered, washed, dissolved in nitric acid and returned to the main solution. The combined solutions, optionally in the presence of a salting out agent such as ammonium nitrate, were subjected to a solvent extraction with, for example, a mixture of diethyl ether, tetrahydrosylvane and nitric acid, the acid being present to reduce extraction thereof from the aqueous phase. The residual aqueous solution may be treated for the recovery of thorium and rare earths whilst the organic phase contained uranium, thorium and cerium. The uranium may be recovered for example by treating the organic solvent phase with water to obtain an aqueous solution from which the uranium may be precipitated with hydrogen peroxide as uranium peroxide. Specification 781,721 is referred to.