Process for the recovery of uranium from wet-process phosphoric acid

摘要

In a process for the recovery of uranium from a wet-process phosphoric acid, comprising treating in an extraction step the preliminarily oxidized acid first with an organic solvent consisting essentially of a dialkylphosphoric acid and a trialkyphosphine oxide dissolved in an inert and unreactive organic solvent whereby there are obtained a uranium-free phosphoric acid and an organic extract consisting essentially of the solvent containing the major portion of uranium; then, in a reextraction step, separating the uranium from the organic extract as ammonium uranyl tricarbonate by reacting the organic extract with ammonium hydroxide and ammonium carbonate; and recycling the uranium-free solvent to the extraction step; an improvement comprises treating the organic extract in a reextraction apparatus having at least two stages, by (a) introducing the extract at the head of the first stage; (b) countercurrently introducing ammonia or ammonium hydroxide solution at the bottom of the first stage; the pH of the first stage being controlled and maintained at a value of 8.0 to 8.5; (c) introducing an ammonium carbonate aqueous solution at the bottom of the last stage; the amount of ammonium carbonate employed being 50-80 percent by weight of the theoretical molar quantity which is necessary to neutralize the dialkylphosphoric acid contained in the solvent and to convert the uranium to ammonium uranyl tricarbonate; and (d) regenerating the ammoniated solvent obtained after the reextraction step by treating it with an acid before recycling it to the extraction step.