Central Glass Company, Limited

Seizi Yoshikawa

Shinsuke Nakagawa

Naoki Okada

Soichi Asagao

Ryuichi Nakamura

An economically advantageous method of recovering uranium from a wet process phosphoric acid solution through the steps of making hemihydrate gypsum contact with the acid solution thereby transferring uranium from the acid solution into the gypsum, dispersing the U-containing gypsum separated from the acid solution in water to convert the gypsum to dihydrate accompanied by the transfer of uranium into water, separating the obtained U-containing aqueous solution from the dihydrate gypsum, and adding precipitant such as an inorganic base to the aqueous solution to form a precipitate comprising an insoluble uranium compound. The contact of hemihydrate gypsum with the phosphoric acid solution is preferably preceded by reduction of hexavalent uranium in the acid solution to tetravalent uranium, and can be achieved either by adding hemihydrate gypsum to the acid solution or by converting dihydrate gypsum to hemihydrate within the acid solution preferably preceded by the addition of sulfuric acid.

Method of recovering uranium from wet process phosphoric acid

In preparing wet process phosphoric acid by decomposing a phosphate rock containing uranium with sulfuric acid and phosphoric acid on condition that hemihydrate gypsum is formed in an acid solution either at the stage of decomposing the phosphate rock or subsequently, uranium contained in the phosphate rock can almost entirely be retained in the obtained phosphoric acid solution by forming the hemihydrate gypsum in the presence of an oxidizing agent, such as a soluble chlorate, hydrogen peroxide or oxygen gas, in the acid solution in a quantity sufficient to render the entire uranium dissolved in the acid solution hexavalent because hemihydrate gypsum adsorbs almost exclusively tetravalent ions of uranium. The uranium is then recovered.

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Yamaguchi, Japan

Seizi Yoshikawa