Effects of organic and aqueous phase composition on uranium extraction from phosphoric acid with octylphenyl acid phosphate

Octylphenyl acid phosphate (OPAP) is a commercially available mixture of monooctylphenyl phosphoric acid (MOPPA) and dioctylphenyl phosphoric acid (DOPPA) that is used to extract U/sup IV/ from wet-process phosphoric acid. The uranium extraction coefficient and the organic phase iron loading were not affected by changes in the organic phase composition due to hydrolysis of the extractant or by different MOPPA/DOPPA ratios in two OPAP batches. The effect of aqueous phase composition was studied in a factorial design test and also by varying the concentrations of the components individually over a range typical of their concentrations in wet-process phosphoric acid. Uranium extraction was decreased by increasing the concentrations of total phosphate, ferric iron, hydrofluoric acid, or total sulfate, and increased by increasing the concentrations of aluminum, magnesium, or silicon. 6 refs