GB849512A - Process for preparing uranium tetrafluoride - Google Patents

Abstract

Uranium tetrafluoride is produced by reducing a solution of a salt of hexavalent uranium electrolytically, and extracting the reduced solution with a solution in an organic solvent of an organic phosphate, amine or chelating agent, and thereafter treating the organic extract with hydrogen fluoride, hydrofluoric acid, ammonium bifluoride or other soluble fluoride to precipitate uranium tetrafluoride. The preferred organic solvent is kerosene and examples of the organic phosphate, amine, and chelating agent are respectively di-2-ethylhexyl hydrogen phosphate, isooctylamine, and thenoyl trifluoro acetone. The initial hexavalent uranium salt solution may be prepared by leaching uranium ore or raw material with sulphuric acid, and if the initial ore contains a considerable amount of gangue, the sulphuric acid solution so obtained may be treated with an organic solvent which takes up the uranium values, and the uranium values may thereafter be stripped from the organic extract with an aqueous solution of sodium carbonate to obtain an aqueous sodium uranyl carbonate solution. This is then acidified with sulphuric or hydrochloric acid to expel the carbon dioxide and employed as the hexavalent uranium salt starting solution. According to an example a uranium ore concentrate was dissolved in 1.5 N sulphuric acid and the solution passed to an electrolytic reduction cell having lead anodes and cathodes separated by an unglazed diaphragm. The solution was reduced at 70 DEG C. and a current density of 8 amperes per square decimetre and the reduced solution was extracted by a solution of di-2ethylhexyl hydrogen phosphate in kerosene. The organic phase was thereafter treated with hydrogen fluoride, hydrofluoric acid or an aqueous solution of ammonium difluoride and the precipitated uranium tetrafluoride was filtered, washed, dried and dehydrated by heating to 350 DEG C.