Effect of ThF₄ Concentration on Th Electrodeposition in CeF₃-ThF₄-LiCl-KCl Molten Salt

In this paper, the electrochemical deposition of Th in CeF₃-ThF₄-LiCl-KCl molten salt with high ThF₄ concentration was studied. When the concentration of ThF₄ increases from 3%（w） to 10%, the initial reduction potential of Th(Ⅳ) has a slight positive shift from -1.75 V to -1.72 V (vs. Ag/AgCl). The increase of Th(Ⅳ) concentration can lead to a positive shift of the initial reduction potential, while the increase of F^- concentration will lead to a negative shift. The initial electrolytic rate and cathodic deposition amount of 10% ThF₄ system are significantly higher than those of 3% ThF₄ system, indicating that the concentration of Th(Ⅳ) is an important factor of the electrolytic extraction of thorium; meanwhile, under the same Th(Ⅳ) concentration, the higher the F^- concentration is, the lower the electrolytic rate will be. The electrolysis results show that the separation rate of Th in 0.3%CeF₃-10%ThF₄-LiCl-KCl molten salt can reach 99.7%, and Ce has almost no electrolytic extraction.