High-efficiency simultaneous extraction of rare earth elements and iron from NdFeB waste by oxalic acid leaching

作     者：Qingsheng Liu Tao Tu Hao Guo Huajin Cheng Xuezhong Wang Qingsheng Liu;Tao Tu;Hao Guo;Huajin Cheng;Xuezhong Wang

作者机构：Faculty of Materials Metallurgy and ChemitryJiangxi University of Science and TechnologyGanzhou 341000China Science SchoolJiangxi University of Science and TechnologyGanzhou 341000 China College of Materials Science and EngineeringJiangsu UniversityZhenjiang 212013China 

出 版 物：《Journal of Rare Earths》 (稀土学报（英文版）)

年 卷 期：2021年第39卷第3期

页      面：323-330,I0004页

核心收录：

学科分类：083002[工学-环境工程] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 080602[工学-钢铁冶金] 080603[工学-有色金属冶金] 0709[理学-地质学] 0819[工学-矿业工程] 08[工学] 0806[工学-冶金工程] 0708[理学-地球物理学] 0703[理学-化学] 

基　　金：Project supported by the National Natural Science Foundation of China(51564019,51674125) the Science and Technology Project of Jiangxi Province Education Department(GJJ181501)。 

主　　题：NdFeB waste Oxalic acid Orthogonal experiment Leaching kinetics Reduction precipitation Rare earths 

摘      要：Iron can not be recovered at high value because only rare earth elements are effectively recovered from NdFeB waste via oxidation roasting-hydrochloric acid leaching process.In this study,a new method for leaching NdFeB waste with oxalic acid was developed.The high-efficiency,simultaneous and high-value recovery of rare earth elements and iron was realized to simplify the process and improve the economic benefit.Results of the oxalic acid leaching experiments show that under the optimum leaching conditions at 90℃ for 6 h in the aqueous solution of oxalic acid(2 mol/L) with a liquid-solid ratio of60 mL/g,the iron leaching efficiency and precipitation rate of rare earth oxalate reach 93.89% and 93.17%,respectively.Rare earth oxalate and Fe(C_(2)O_(4))3^(3-) were left in the residue and the leaching solution,respectively.The leaching mechanism was further analyzed by characterising the leach residues obtained through X-ray powder diffraction(XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS).Results of the leaching kinetics study indicate that the process of oxalic acid leaching follows the shrinking nucleus model,and the leaching kinetics model is controlled by the mixed factors of diffusion and chemical reaction.The leaching residue was calcined at 850℃ for 3 h and then decomposed into rare earth oxide,which can be directly used to prepare rare earth alloy via molten salt electrolysis.For the leaching solution,ferric oxalate solution was reduced using Fe powder to prepare the ferrous oxalate(FeC_(2)O_(4)-2H_(2)O).