Recovery of trivalent lanthanides and actinides from water deficient nitrate media by TBP-extraction

The equilibrium distributions of trivalent lanthanides, Am and Cm were experimentally studied in the bi-phase extraction system of TBP-dodecane and molten Ca(NO3)2xxH2O (hydrate melt) having different water content. The systematics of the distribution ratios along lanthanides series was analyzed. It was found that the distribution ratios of lanthanides and actinides ar quite high and show logarithmically linear increase on log[TBP] in the low TBP concentration (< 0.1 mol/1). It was also found that they were influenced by the extraction of calcium in the high [TBP] region (> 0.1 mol/1). The influence of the water content in the hydrate melt was studied and it was shown that even a small increase of water content significantly lowers the extraction of trivalent elements. These characteristics of the TBP extraction using hydrate melt of Ca(NO3)2 were compared with TBP extraction system using concentrated nitric acid as inorganic phase. Based on the experimental results, feasibility and condition of the extraction recovery of trivalent lanthanides and actinides by the TBP from hydrate melt of Ca(NO3)2 were discussed. (author)