Removal of rare earth fission products from LiCl-KCl molten salt by sulfide precipitation

The precipitation reaction of rare earth was investigated by potassium sulfide (K₂S), or sodium sulfide hydrate (Na₂S·xH₂O) in LiCl-KCl melts. The characteristics of precipitates were determined and the removal ratios of rare earth were compared under different conditions. For both precipitants, the rare earth removal ratios were up to 90%. Rare earth sulfides were mainly observed in K₂S precipitation reaction, while some oxysulfide species were identified for Na₂S·xH₂O, which showed the synergistic effect of S and O on the removal efficiency. The research results suggested that sulfide precipitation was feasible to separate rare earth products from waste salts. (author)