Evaluation of noble metals as reactive electrodes for separation of lanthanides from molten LiF-BeF2

Abstract

Thermodynamic evaluation for the employment of Au/Pt/Ag noble metals as reactive electrodes for the reduction and extraction of lanthanides (Ln) from LiF-BeF₂ melt is systematically considered in this study. The standard reduction potential of the typical lanthanides Nd/Pr/Gd/Sm/Eu and their most stable intermetallics with Au/Pt/Ag noble metals and Ni/Cu/Al non-noble metals is calculated using the data from the literature or HSC6.0 software. The results indicate that the depolarization effect on the reduction of lanthanides is in the order of Au ≈ Pt ≫ Al > Ni ≈ Cu > Ag. The noble metals Au and Pt possess excellent capability for the extraction of nearly all species of lanthanides from the LiF-BeF₂ melt. The results are confirmed by experimental investigation of a typical LiF-BeF₂-LnF₃ molten salt system.