Iron Scrubbing From D₂EHPA and TOPO Mixture During Second Cycle of Uranium Extraction From Phosphoric Acid Using Oxalic Acid

The iron scrubbing from organic mixture, 0.03 M D₂ EHPA and 0 .075 M TOPO was carried out using oxalic acid solution. The influence of various factors affecting the scrubbing process as shaking time, oxalic acid concentration, scrubbing temperature and aqueous/organic phase ratio has been studied in terms of the maximum iron scrubbing efficiency and the minimum uranium scrubbing efficiency. The obtained results have been mathematical treated in order to model the iron scrubbing process. The logarithm of the apparent scrubbing equilibrium constant K was calculated and found to equal -1.55 ± 0.09. The iron scrubbing process shown the endothermic character and the thermodynamics parameters (∆ H, ∆ G and ∆ S) were 20.17 K J/mol, 8.84 K J/mol and 38.02 J/mol K respectively. By applying the optimum conditions for iron scrubbing process, it is found that one stage is sufficient for scrubbing about 96.0 % of the total iron in loaded organic phase. The iron concentration in the precipitated yellow cake was with in the permissible limits of the yellow cake international standard. (author)