Uranium(VI) extraction from concentrated Egyptian wet-process phosphoric acid using a synergistic organophosphorous solvent mixture

Abstract

Uranium(VI) recovery from concentrated Egyptian hemi-dihydrate wet-process phosphoric acid, 9.2 M, is investigated using synergistic organophosphorous solvent mixture of dinonyl phenyl phosphoric acid (DNPPA) and tris(2-ethylhexyl)phosphate (TEP). The effect of various factors such as [DNPPA] concentration, [TEP] concentration, phosphoric acid concentration, shaking time, aqueous: organic phase’s ratio (Vaq/Vorg), stability of the solvent, the diluents effect, and temperature on the degree of extraction has been established. The effect of different stripping agents was investigated. The enthalpy change of the uranium extraction process was determined and the extracted uranium is further subjected to a second cycle of extraction [0.3 M D2EHPA + 0.075 M TOPO], scrubbing impurities (5 M sulfuric acid), and finally stripping with 1 M (NH4)2CO3 solution. Precipitation of uranium in highly pure UO3 product using hydrogen peroxide and heat treatment at 375 °C were carried out.