Stripping of Uranium from D2EHPA/TOPO Solvent by Ammonium Carbonate Solutions

Abstract

Uranium is recovered from phosphoric acid by the D2EHPA/TOPO process. In this process uranium is stripped from the loaded D2EHPA /TOPO solvent in the second cycle by an ammonium carbonate solution. This paper studied stripping of uranium from 0.3 mol/L D2EHPA / 0.075 mol/L TOPO in kerosene by different ammonium carbonate solutions. The ammonium carbonate solutions tested were either prepared locally from ammonia and carbon dioxide gases or commercial and laboratory grades available on the market. A comparison was made between these carbonate solutions in terms of purity, stripping efficiency and phase separation. Both stripping and phase separation were carried out under different conditions of phase ratios and concentrations. The results obtained showed that ammonium carbonate prepared from direct reaction of ammonia and carbon dioxide gases had a high purity and gave the same stripping yield as the laboratory grade. The phase separation was also slightly improved using a pure synthesized ammonium carbonate solution. The phase separation was found to be the best at a concentration of 0.5 mol/L ammonium carbonate solution and at a phase ratio A/O of 1/1 and a temperature of 50 °C. It was possible to obtain > 99\% yield of uranium by operating 2 stripping stages counter-currently under these conditions.