Effect of organic diluents on the extraction of uranium from phosphoric acid

Abstract

Phosphoorganic solvents such as OPPA, DEPA/TOPO and OPAP are commonly used to extract uranium from wet phosphoric acid. They are used in concentrations between 1–10% wt/wt in organic diluents. These inert organic substances serve to dilute the solvent, decrease its viscosity and secure a greater contact between the acid and the solvent. The diluents should also be cheap, readily available, immiscible with water and volatile at the temperature of the extraction which is from 30–50°C. They should not reduce the extraction coefficient of the solvent and separate well at the temperature of separation as an organic phase. This study was carried out to investigate the effect of various organic diluents in order to select the most suitable one. It is established that paraffinic diluents are better than aromatic ones. Since kerosene is cheap, available and not very volatile at the temperature of extraction, it is commonly used in extraction. However, the kerosene used should be treated to reduce the aromatic content to a minimum.