Extraction of uranium values from phosphoric acid

摘要

Aqueous phosphoric acid solutions containing uranium values are contacted with an organic solution of a mixture of organophosphorus compounds produced from a carboxylic acid and PCl3 in the presence of water or from corresponding acid halides or anhydrides and phosphorous acid to extract the uranium values. The organophorus compounds generally include an alkane-1,1,2-triphosphonic acid or a 1-hydroxy-1,1-alkanediphosphonic acid or both, which differ from common organophosphorus extractants in having a carbon-phosphorus bond. The extraction has high distribution coefficients even when the phosphoric acid solution is 10 molar or more and even when the extraction is conducted at elevated temperatures such as 60 DEG C. While distribution coefficients in the presence of iron are higher for tetravalent uranium, efficient extraction can be conducted of hexavalent uranium as well. Uranium values are recovered from the organic solution by contacting it with about 40-70 weight percent aqueous HF and separating a uranium-rich precipitate from the solution.