Extraction and separation of uranium, thorium and cerium from different mixed media with HDEHP

Systematic studies were carried out on the extraction of U(VI), Th(IV) and Ce(III) with HDEHP from pure hydrochloric and sulfuric acid solutions as well as from their binary mixtures. The influence of water-miscible alcohols and acetone on the extraction of these elements was also investigated. Results were discussed and procedures for the separation of the concerned elements have been recommended. The removal of fission products (rare earths, etc.) from uranium is one of the most important separation problems in reactor chemistry. Ce(III) can be eliminated from U(VI) at 4.5M HCl or H2SO4 solutions as well as at 2.5M HCl in presence of 50 % ethanol which is more plausible. For the stripping of U(VI) from the organic phase, successive with 11M HCl can be used. U-Th separation can be achieved by successive extraction at 11M HCl or 4.5M HCl in presence of 50 % ethanol. Higher separation factors for these elements could be obtained when working in HCl-H2SO4 solutions. Thorium can easily be separated from Ce(III) at 4.5M HCl or at 5M H2SO4. The addition of isopropyl alcohol is recommended for the separation of Th-Ce(III). Quantitative separation for Th-Ce(III) can be achieved from HCl-H2SO4 media. A suggested extraction mechanism is presented in the light of the obtained results. (T.G.)