The Chlorination Of La₂O₃ And CeO₂ With Aluminium Chloride And Formation Of Al-RE Alloys In Molten Salts

A series of methods were adopted to research the chlorination of different valence rare earth oxides（La₂O₃,CeO₂）with AlCl₃ in molten LiCl-KCl system.The Al-RE（Al-La,Al-Ce）alloyswereproducedbypotentiostaticelectrolysisin LiCl-KCl-AlCl₃-rare earth oxides（La₂O₃,CeO₂）in order to confirm the rare earth oxides chloride by AlCl₃.Rare earth oxide（La₂O₃,CeO₂）was chlorinated by AlCl₃ in molten LiCl-KCl system using physical methods.The rare earth ions（La（III）and Ce（III））concentration in the supernatant was determined in molten LiCl-KCl-rare earth oxides（La₂O₃ and CeO₂）system before and after the addition of AlCl₃ by ICP-AES.The supernatant and deposit in molten LiCl-KCl-rare earth oxides（La₂O₃ and CeO₂）system were analyzed by XRD.The results showed that RECl₃ existed in molten salts.The Gibbs free energies of chloride reaction in the molten salt were calculated in order to determine direction of reaction by thermodynamic data.The results indicated that chlorination reaction could be proceed.The electrochemical behavior of LiCl-KCl-AlCl₃-rare earth oxides（La₂O₃ and CeO₂）was investigated to confirm the chlorination of rare earth oxides using a series of electrochemical methods such as cyclic voltammograms,square wave voltammetric,chronopotentiometry and open circuit chronopotentiometry.The electrochemical signals of rare earth ions（La（III）and Ce（III））and Al-RE alloy compounds were observed in LiCl-KCl-AlCl₃-Rare earth oxides（La₂O₃ and CeO₂）system.The results showed that rare earth oxides could be chloridized byAlCl₃ and underpotential deposition of rare earth（La and Ce）ions occurred on the pre-deposited Al electrod due to the formation of Al-RE intermetallic compounds.The diffusion coefficients of La（III）and Ce（III）were calculated in LiCl-KCl molten salts.The Al-La and Al-Ce alloy were prepared by potentiostatic electrolysis LiCl-KCl-AlCl₃-rare earth oxides（La₂O₃ and CeO₂）.The electrochemical mechanisms of preparing the Al-RE alloys were discussed.The process parameters were obtained.Al-La and Al-Ce alloy samples were characterized by XRD and ICP-AES.The results showed that Al-La alloy consisted of Al₂La and Al₃La phases.While for Al-Ce alloys,Al₁₁Ce₃ and AlCe phases were transformed into Al₂Ce phase when the content of AlCl₃ increased from 5.0 wt.%to 15.0 wt.%in LiCl-KCl-AlCl₃-CeO₂ system.