Molten Salt/Liquid Metal (Bi-Li) Reduction Extraction Of Rare Earth Ce And Sm

The rare earth,called“industrial vitamin”,is the material underpinnings for national high and new technology.The rare earth is considered to be one of the important strategic resources for the development of national security.The rare earth and its alloys have a widely application in energy,metallurgy,machinery,chemical industry,electronics and other fields,thus it is meaningful for the preparation of rare earth and its alloys.It is important to remove rare earth elements in spent fuel reprocessing.Separating and extracting rare earths from the spent fuel can improve the utilization of nuclear fuel and ensure the safety of nuclear power for sustainable development.Therefore,The separation and purification of rare earth elements,Ce?III?and Sm?III?,were studied by reduction extraction in molten salt/liquid metal?Bi-Li?.In order to prepare the Bi-Li alloy,the electrochemical behaviors of Li?I?on a Bi film electrode and liquid Bi electrode were studied in LiCl-KCl molten salt.Compared with W electrode,two new peaks were observed at-1.75 V and-1.9 V,which indicated that the underpotential deposition of Li?I?occured due to the formation of two Bi-Li intermetallic compounds.According to the phase diagram,the two kinds of alloy should be BiLi and BiLi₃,respectively.And the Bi-Li alloys were preparedbygalvanostatic electrolysis at different conditions.The extraction of Ce through the molten salt/liquid metal?Bi-Li?at different temperature was studied.At different temperature,ICP-AES analysis was used to determine the Ce content in extraction solvent and extraction phase,respectively,during the extracting process.And then,the distribution and extraction rate were calculated.The experimental results indicated that the optimumtemperature of extraction is 823 K,distributionratio3.86 and the extraction rate54%.The effect ofLi content in the Bi-Li alloyon extraction result was also studied in the process of extraction Ce.The results showed that the distribution ratio is 3.86 and the extraction rate54%using the extraction solvent?Bi-Li alloy?prepared by electrolysis for 180min.The relationship between current densities and concentration of rare earth ions were determined by square wave voltammetry and ICP-AES and standard work curves were obtained in the extraction process of Ce?III?and Sm?III?in the molten salt under different conditions.The change of current densities was monitored by square wave voltammetry during the extraction of Ce?III?and Sm?III?from LiCl-KCl molten salts,respectively,at different temperature.Compared with the standard work curves,the changes of Ce?III?and Sm?III?concentration were obtained and the distributionratio and the extraction rate were also evaluated.The results showed that optimued temperatures of extracting Ce?III?and Sm?III?from LiCl-KCl molten salts were both 823 K.The extractingCe?III?and Sm?III?from LiCl-KCl-CeCl₃-SmCl₃ molten salts were also investigated.The change of current densities was monitored by square wave voltammetry during the extraction of Ce?III?and Sm?III?from LiCl-KCl molten salt at different temperature.Compared with the standard work curves,the changes of Ce?III?and Sm?III?concentration were obtained and the distributionratio and the extraction rate were also evaluated.The results indicated that the extraction ratewas the fastest at 823 K,which was consistent with the one obtained from single rare earth ions?Ce?III?or Sm?III??in the molten salts.The effect of agitation speed on extraction rate was studied.The results showed that the extraction rates for extracting Ce?III?or Sm?III?were the fastest at agitation speed of 100r/min.