Stripping of iron (III) from the D2EHPA + TBP extract produced during uranium recovery from phosphoric acid by oxalic acid

A process employing oxalic acid to separate iron from the organic phase composed of 1.5 M D2EHPA + 0.2 M TBP obtained in the second cycle operation during processing of phosphoric acid for uranium recovery has been developed and tested by bench scale counter-current operations. The process has been studied to optimize various process variables such as equilibration time, temperature, concentration of oxalic acid, iron concentration in organic phase and phase ratio for effective separation of iron. The stripping of iron was found to follow first order kinetics with an activation energy of 77 kJ/mole. Under optimized process parameters, a four stage counter-current stripping of iron has been carried out from an extract comprised of 1.5 M D2EHPA + 0.2 M TBP + 1.12 g/L Fe + 14.8 g/L U3O8 with 7.5 wt.% oxalic acid using an organic to aqueous phase ratio (O / A) of 3 at 50 °C. It yields an extract with only traces of iron. From the resulting extract yellow cake exceeding the specification of commercial grade has been produced.