Uranium recovery from wet process phosphoric acid

摘要

Improvement in the process for recovering uranium from wet-process phosphoric acid solution derived from the acidulation of uraniferous phosphate ores by the use of two ion exchange liquid-liquid solvent extraction circuits in which in the first circuit (a) the uranium is reduced to the uranous form; (b) the uranous uranium is recovered by liquid-liquid solvent extraction using a mixture of mono- and di-(alkyl-phenyl) esters of orthophosphoric acid as the ion exchange agent; and (c) the uranium oxidatively stripped from the agent with phosphoric acid containing an oxidizing agent to convert uranous to uranyl ions, and in the second circuit (d) recovering the uranyl uranium from the strip solution by liquid-liquid solvent extraction using di(2-ethylhexyl)phosphoric acid in the presence of trioctylphosphine oxide as a synergist; (e) scrubbing the uranium loaded agent with water; (f) stripping the loaded agent with ammonium carbonate, and (g) calcining the formed ammonium uranyl carbonate to uranium oxide, the improvement comprising: (1) removing the organics from the raffinate of step (b) before recycling the raffinate to the wet-process plant, and returning the recovered organics to the circuit to substantially maintain the required balance between the mono and disubstituted esters; (2) using hydogren peroxide as the oxidizing agent in step (c); (3) using an alkali metal carbonate as the stripping agent in step (f) following by acidification of the strip solution with sulfuric acid; (4) using some of the acidified strip solution as the scrubbing agent in step (e) to remove phosphorus and other impurities; and (5) regenerating the alkali metal loaded agent from step (f) before recycling it to the second circuit.