Kinetics study on leaching of rare earth and aluminum from polishing powder waste using hydrochloric acid
来源期刊：JOURNAL OF RARE EARTHS2020年第9期
论文作者：Xitao Wu Zhijian Wang Chuping Xia Xuefeng Shi Tianzong Luo Xinjun Bao Rongli Liu Shengzhong Xie
文章页码：1009 - 1018
摘 要：In this study,a novel hydrometallurgical process consisting of hydrochloric acid three-stage countercurrent leaching and solvent extraction was proposed to recover rare earth oxide（REO） from the rare earth polishing powder waste（REPPW）.The effects of HCI concentration,liquid-solid ratio（L/S ratio）,temperature and time on the leaching yields of rare earths（in REO） and aluminum（in Al2O3） were studied.The result shows that the leaching yields of REO and Al2O3 are 90.96% and 43.89% respectively under the optimum leaching parameters of HCl concentration=8.00 mol/L,L/S ratio=4 mL/g,leaching temperature=353 K and leaching time=180 min.Meanwhile,the leaching kinetics of REO and Al2O3 were investigated in this study.The leaching behaviors of REO and Al2O3 follow a shrinking sphere/core model and the general leaching process is controlled by the surface chemical reaction.The leaching activation energies of REO and Al2O3 are 9.86 and 13.68 kJ/mol,respectively.The leaching yield of each substance in three-stage countercurrent leaching is improved substantially compared with single-stage leaching,with a change from 90.96% to 95.38% for REO and from 43.89% to 46.22% for Al2O3,respectively.Especially,the total concentration of REO in three-stage countercurrent leaching solution is greatly increased to above 300 g/L,and the acidity of which is decreased to ca.pH=2,which is conducive to subsequent solvent extraction directly.High purity REO（99.92%） is obtained by solvent extraction separation,oxalate precipitation and calcination.The total recovery yield of REO is 85.13%.
Xitao Wu1，Zhijian Wang1，Chuping Xia1，Xuefeng Shi1，Tianzong Luo1，Xinjun Bao2，Rongli Liu1，Shengzhong Xie3
1. Hunan Rare Earth Metal Material Research Institute2. School of Chemistry and Chemical Engineering,Central South University3. Hunan Nonferrous Metals Vocational and Technical College
摘 要：In this study,a novel hydrometallurgical process consisting of hydrochloric acid three-stage countercurrent leaching and solvent extraction was proposed to recover rare earth oxide（REO） from the rare earth polishing powder waste（REPPW）.The effects of HCI concentration,liquid-solid ratio（L/S ratio）,temperature and time on the leaching yields of rare earths（in REO） and aluminum（in Al2O3） were studied.The result shows that the leaching yields of REO and Al2O3 are 90.96% and 43.89% respectively under the optimum leaching parameters of HCl concentration=8.00 mol/L,L/S ratio=4 mL/g,leaching temperature=353 K and leaching time=180 min.Meanwhile,the leaching kinetics of REO and Al2O3 were investigated in this study.The leaching behaviors of REO and Al2O3 follow a shrinking sphere/core model and the general leaching process is controlled by the surface chemical reaction.The leaching activation energies of REO and Al2O3 are 9.86 and 13.68 kJ/mol,respectively.The leaching yield of each substance in three-stage countercurrent leaching is improved substantially compared with single-stage leaching,with a change from 90.96% to 95.38% for REO and from 43.89% to 46.22% for Al2O3,respectively.Especially,the total concentration of REO in three-stage countercurrent leaching solution is greatly increased to above 300 g/L,and the acidity of which is decreased to ca.pH=2,which is conducive to subsequent solvent extraction directly.High purity REO（99.92%） is obtained by solvent extraction separation,oxalate precipitation and calcination.The total recovery yield of REO is 85.13%.
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