用于稀土废料电解回收的LiF-NaF-KF和NaCl-KCl熔盐体系物化性质研究  

Study on the Physical and Chemical Properties of LiF-NaF-KF and NaCl-KCl Molten Salt Systems for Electrolytic Recycling of Rare Earth Waste

作　　者：邵铭杰 王长治 林勇 肖万海 谭宁 魏奎先[1] 王东[2,3] SHAO Mingjie;WANG Changzhi;LIN Yong;XIAO Wanhai;TAN Ning;WEI Kuixian;WANG Dong(Faculty of Metallurgy and Energy Engineering,Kunming University of Science and Technology,Kunming 650093,China;Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China;Ganjiang Innovation Academy,Chinese Academy of Sciences,Ganzhou 341119,China)

机构地区：[1]昆明理工大学冶金与能源工程学院,昆明650093 [2]中国科学院过程工程研究所,北京100190 [3]中国科学院赣江创新研究院,江西赣州341119

出　　处：《有色金属工程》2024年第8期77-86,共10页Nonferrous Metals Engineering

基　　金：国家自然科学基金资助项目(52304336)。

摘　　要：熔盐电解法是回收钕铁硼废料的重要方法,氟化物和氯化物常被用来当作回收稀土废料熔盐体系中的电解介质。熔盐物性对电流效率、电耗、回收率以及回收产物形态等具有重要的影响。首先对Nd、Pr和Fe在LiF-NaF-KF和NaCl-KCl中的热力学行为进行讨论,进一步采用旋转法、阿基米德法和拉筒法研究了不同配比熔盐体系在不同温度下的黏度、密度和表面张力变化。结果表明:在LiF-NaF-KF系中Nd、Pr会与NaF、KF自发反应;Nd和Pr元素平衡溶解度分别为2.34 mg/g以及1.07 mg/g,而Fe元素则基本不溶解。对于NaCl-KCl体系,钕铁硼废料各组分的反应都不会自发进行,在电解之前需将Fe^(3+)沉淀以免在电解时优先沉积。两种熔盐体系的黏度、密度和表面张力均随温度的升高而降低,密度随温度的改变更符合线性关系,线性程度均大于0.95;随着NdF 3和AlCl_(3)-Nd_(2)O_(3)用量的增加,两种体系的黏度、密度和表面张力均有所增加,但电解原料的添加未改变温度对体系密度的影响规律。Molten salt electrolysis is an important method for recycling NdFeB scrap.Fluoride and chloride are often used as electrolytic media in molten salt systems for recycling rare earth scrap.The physical properties of molten salt have an important impact on current efficiency,power consumption,recovery rate and form of recovered products.This article first discusses the thermodynamic behavior of Nd,Pr and Fe in LiF-NaF-KF and NaCl-KCl,and further uses the rotation method,Archimedes method and tube drawing method to study the molten salt systems with different proportions at different temperatures.Changes in viscosity,density and surface tension.The results show that in the LiF-NaF-KF system,Nd and Prspontaneously react with NaF and KF;The equilibrium solubility of Nd and Pr elements are 2.34 mg/g and 1.07 mg/g respectively,while Fe Elements are basically insoluble.For the NaCl-KCl system,the reactions of each component of NdFeB scrap not proceed spontaneously.Fe^(3+)needs to be precipitated before electrolysis to avoid its preferential deposition during electrolysis.The viscosity,density and surface tension of the two molten salt systems all decrease with the increase of temperature.The change of density with temperature is more consistent with a linear relationship,and the linearity degree is greater than 0.95.As the amounts of NdF 3 and AlCl_(3)-Nd_(2)O_(3) increase,the two systems,the viscosity,density and surface tension all increased,but the addition of electrolytic raw materials did not change the influence of temperature on the density of the system.

关 键 词：熔盐电解 物化性质 稀土 钕铁硼废料 

分 类 号：TF845[冶金工程—有色金属冶金]