Wet phosphoric acid is a nonnegligible source of uranium but the exploitation of those unconventionalresources is quite difficult due to the high complexing power and the highconcentration of phosphoric acid. In 1980's, the synergistic mixture ofbis-(2-ethyl-hexyl)-phosphoric acid (D2EHPA) and tri-n-octylphosphine(TOPO) was implemented in solvent extraction processes to recover uranium (VI)from WPA. Despite of numerous works on the physicochemistry involved in theextraction of uranium (VI) from concentrated phosphoric acid by D2EHPA/TOPO,some discrepancies on the description of this system have been reported in theliterature. This paper presents a thermodynamic model to describe the distributioncoefficient of uranium (VI) between 5.3 mol L-1 phosphoric acid andD2EHPA/TOPO diluted in Isane as a function of D2EHPA concentration at constantconcentration of TOPO (0.125 mol L-1) and as a function of TOPOconcentration at constant D2EHPA concentration (0.5 mol L-1).

Modeling of the extraction properties of uranium (VI) from concentrated phosphoric acid by a synergistic mixture of D2EHPA and TOPO

243rd National Meeting (2012)

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