Reductive Extraction of Lanthanide and Actinide Elements from Molten LiF-BeF2 Salt into Liauid Bismuth

Abstract

The equilibrium distributions of several lanthanide and actinide elements between molten LiF-BeF₂ salt and liquid bismuth were determined over a wide range of salt composition at some temperatures from 600 to 800°C. The distribution behavior of each element was ap-parently affected by salt composition and temperature. The effect of salt composition on the distribution behavior was well explained by considering the formation of complex in the salt phase. Also, the excess free energies of the solutes in the bismuth phase, calculated from the equilibrium distribution data, were considerably negative, which suggests the for-mation of intermetallic compound in the bismuth phase. Taking into account the formation of these compounds, the equilibrium distribution can be expressed as
Li_(m-n)MF_m+nLi+x Bi=MBi_x+m LiF.