Book Description

The OPPA process offers three potential advantages over the DEPA-TOPO process. The OPPA extractant is much less expensive and has a higher extraction power for uranium than the DEPA-TOPO solvent. In addition it extracts U(IV), the prevailing oxidation state of uranium in wet-process phosphoric acid and this eliminates the liquor oxidation step required in the DEPA-TOPO process. However, the DEPA-TOPO solvent is known to be extremely stable and this process has been successfully demonstrated on a pilot-plant scale at phosphate plants. It is understood that several companies are planning to commercialize this process in the near future. On the other hand, the potentially more attractive OPPA process has not been proven in a pilot plant operation and some questions about the solubility and stability of the OPPA need to be answered. Because of the wide spread interest in this process, a program was started in cooperation with Mobil and Allied Chemical companies to study this extractant, to identify and isolate the material that solubilizes the mono- and diacids, and to determine the optimum concentration and ratios for uranium extraction. In addition, a long-term cyclic test is planned to better define solubility losses and stability of the extractant. Consideration will also be given to improving the recovery of uranium lost to the gypsum during calcination. 12 figures. (auth).