稀土熔盐电解研究现状

Current Research Status of Rare Earth Molten Salt Electrolysis

介绍了熔盐电解制备稀土金属的电解质体系以及国内外近年来熔盐电解制备稀土金属的研究进展,阐述了稀土离子在不同体系不同电极下的还原电位以及还原路径。镧系稀土中La、Ho、Er、Tb、Gd均为一步还原三电子,即Re(III)+3e--→Re;Tm为两步还原,即Tm(III)+e-Tm(II)、Tm(II)+2e'→Tm;Nd、Dy在不同条件下其还原路径会发生改变;Sm无法在情性电极上电沉积得出,电沉积在活性电极上可与电极反应生成稀土金属间化合物,导致稀土金属发生欠电势沉积。在镧系之外的稀土金属中Y为一步还原三电子过程;U以LiCl-KCl-UF,体系下分为两个步骤,即U(IV)+e'-→U(II)、U(III)+3e'—→U。

The electrolyte system for the preparation of rare earth metals by molten salt electrolysis and the research progress of the preparation of rare earth metals by molten salt electrolysis at home and abroad in recent years are introduced,and the reduction potentials of rare earth ions at different electrodes in different systems as well as the reduction paths are described.Among the lanthanide rare earths presented in this paper,La,Ho,Er,Tb,Gd are one-step reduction with three electrons,i.e.,Re(III)+3e'→Re.Tm is a two-step reduction,i.e.,Tm(III)+e'-→Tm(II),Tm(II)+2e'-→Tm.The reduction paths of Nd,Dy are changed in different conditions.Sm can not be derived from the electrodeposition on the inert electrodes,and electrodeposition on the active electrode can react with the electrode to generate rare earth intermetallic compounds,leading to underpotential deposition of rare earth metals.In rare earth metals other than lanthanides,Y is a one-step reduction three-electron process;U is divided into two steps under the LiCl-KCl-UF4 system,i.e.,U(IV)+e'→U(III),U(III)+3e-→U.