STUDY OF THE STABILITY OF OCTYL PYROPHOSPHORIC ACID (OPPA) SOLVENT INTHE EXTRACTION OF URANIUM FROM PHOSPHORIC-ACID

Octyl pyrophosphoric acid (OPPA) solvent is used for the extraction of uranium from wet phosphoric acid both in pilot and commercial plants. It is widely known that the extraction factor K of OPPA is much highe r than for other competing solvents such as octyl phenyl phosphoric ac id (OPAP) or diethylhexyl phosphoric acid/trioctyl phosphine oxide (DE HPA/TOPO). However, this solvent is unstable due to the weak bond P-O- P which hydrolyses readily under the influence of time, temperature an d contact with acids. The present study investigates the influence of time, temperature, storage time and contact with different acids on th e strength of OPPA and has established that the stability decreases wi th an increase in temperature, storage time and contact with acids.