Equilibrium distribution of lanthanum,neodymium, and thorium between fluoride salt melts and liquid bismuth

The extraction of lanthanum, neodymium, and thorium from 73LiF-27BeF₂, 78LiF-22ThF₄, 75LiF-5BeF₂-20ThF₄, 15LiF-58NaF-27BeF₂, and 60LiF-40NaF (mol %) fluoride salt melts into liquid bismuth with admixtures of lithium as a reducing agent was studied at 580–750°C. Equilibrium values of their distribution coefficients were measured. Beryllium as distinct from neodymium and lanthanum almost was not extracted into bismuth from salt beryllium-containing compositions. A decrease in the mole fraction of LiF in LiF-BeF₂ melts substantially increased the effectiveness of its purification from lanthanides. The LiF-ThF₄ and LiF-BeF₂-ThF₄ salt mixtures with comparatively high thorium concentrations (≥20–22 mol %) could not be used for effective separation of lanthanides and thorium in a system for extraction processing of fuel salts.