Recovery of rare earth elements(REEs)from bulk Nd-Fe-B scrap by chlorination with NH_(4)Cl as a chlorinating agent has been reported to be an energy efficient and environmentally friendly method.However,the reaction m...Recovery of rare earth elements(REEs)from bulk Nd-Fe-B scrap by chlorination with NH_(4)Cl as a chlorinating agent has been reported to be an energy efficient and environmentally friendly method.However,the reaction mechanism and phase evolution of the low-temperature selective chlorination process of Nd-Fe-B sludge are not clear.In this paper,we systematically investigated the lowtemperature selective chlorination process of Nd-Fe-B sludge with NH4Cl by combining thermokinetic theoretical calculations and experiments,and revealed its reaction mechanism.The phase evolution during chlorination was determined by X-ray diffraction(XRD),scanning electron microscopy(SEM)and ene rgy-dispersive X-ray spectroscopy(EDS)characterization as well as co mputational analysis of the phase stability diagram of the M-O-Cl system.To determine the optimum chlorination conditions,the effects of chlorinating agent dosage,reaction temperature and reaction time on the reaction were investigated.The results show that the rare earth components in Nd-Fe-B sludge are selectively chlorinated to RECl3and the formation of REOCl is avoided in the temperature range of 300-420℃,while the iron components are preferentially oxidized to Fe2O3.The selective chlorination reaction is consistent with the unreacted shrinking core model,and the rate-controlling step of the reaction is the internal diffusion process of NH4Cl through the transition layer of the reactant product to the surface of the Nd-Fe-B sludge.The complete chlorination of REEs is successfully achieved and 99.8%of REEs are selectively extracted into the leaching solution under optimal chlorination conditions(300℃,2.5 times of stoichiometric amount,4 h).展开更多
Vanadium extraction of vanadium-bearing titanomagnetite was investigated by selective chlorination. Thermodynamics analyses on the interactive reactions among related species in the system were made before the experim...Vanadium extraction of vanadium-bearing titanomagnetite was investigated by selective chlorination. Thermodynamics analyses on the interactive reactions among related species in the system were made before the experiments. Some fundamental experiments for extracting vanadium by FeClx as chlorinating agent were conducted over the temperature range of 900-1300 K under air or oxygen atmosphere. The results show that vanadium can be extracted by the selective chlorination, using FeClx, based on thermodynamic analysis and experiment. Vanadium extraction ratio first increases with the increase of temperature, and then decreases with the increase of temperature over the range of 900-1300 K under air or oxygen atmosphere. The higher molar ratio of FeCI3 to oxides （nchl：noxd） reacting with FeC13, the higher ratio of vanadium extraction. Under oxygen atmosphere, the vanadium extraction ratio is up to 32% at 1100 K for 2 h by using FeCI3 as chlorinating agent.展开更多
Due to the lack of effective screening systems in the rare earth waste recycling industry,the composition of rare earth elements in rare earth waste is complex and difficult to separate.In response to such problems,by...Due to the lack of effective screening systems in the rare earth waste recycling industry,the composition of rare earth elements in rare earth waste is complex and difficult to separate.In response to such problems,by studying the reaction behavior between various elements in rare earth waste and cobalt chloride,we propose a process path for the separation and recovery of iron,cerium and other rare earth elements using cobalt chloride roasting.The experiments on simulated wastes show that the leaching rates of the Nd,Sm,Gd,Pr can reach 98.31%,94.5%,93.87%and 72.05%under the optimal process conditions,respectively.Ce and iron remain in the leaching residue in the form of CeO_(2)and CoFe_(2)O_(4),respectively.And through a simple magnetic separation process,CeO_(2)and CoFe_(2)O_(4)can be enriched in non-magnetic leaching residue and magnetic leaching residue,respectively.The cerium content in the leaching residue composed of cobalt ferrite is only 1.95%.Therefore,this method is beneficial to the separation and high-value utilization of iron,cerium,and other rare earth elements in the waste system.The research results can provide theoretical reference for the low-cost and high-value recovery of rare earth secondary resources.展开更多
基金Project supported by the National Natural Science Foundation of China(52261037,52401251)Key Research Project of Jiangxi Province(20203ABC28W006)+2 种基金the Research Fund of Key Laboratory of Rare Earths,Chinese Academy of SciencesKey Laboratory of Ionic Rare Earth Re sources and Environment,Ministry of Natural Resources of the People's Republic of China(2022IRERE302)the Ganzhou Science and Technology Innovation Empowerment Youth"Jie bang Gua shuai"Project。
文摘Recovery of rare earth elements(REEs)from bulk Nd-Fe-B scrap by chlorination with NH_(4)Cl as a chlorinating agent has been reported to be an energy efficient and environmentally friendly method.However,the reaction mechanism and phase evolution of the low-temperature selective chlorination process of Nd-Fe-B sludge are not clear.In this paper,we systematically investigated the lowtemperature selective chlorination process of Nd-Fe-B sludge with NH4Cl by combining thermokinetic theoretical calculations and experiments,and revealed its reaction mechanism.The phase evolution during chlorination was determined by X-ray diffraction(XRD),scanning electron microscopy(SEM)and ene rgy-dispersive X-ray spectroscopy(EDS)characterization as well as co mputational analysis of the phase stability diagram of the M-O-Cl system.To determine the optimum chlorination conditions,the effects of chlorinating agent dosage,reaction temperature and reaction time on the reaction were investigated.The results show that the rare earth components in Nd-Fe-B sludge are selectively chlorinated to RECl3and the formation of REOCl is avoided in the temperature range of 300-420℃,while the iron components are preferentially oxidized to Fe2O3.The selective chlorination reaction is consistent with the unreacted shrinking core model,and the rate-controlling step of the reaction is the internal diffusion process of NH4Cl through the transition layer of the reactant product to the surface of the Nd-Fe-B sludge.The complete chlorination of REEs is successfully achieved and 99.8%of REEs are selectively extracted into the leaching solution under optimal chlorination conditions(300℃,2.5 times of stoichiometric amount,4 h).
基金Projects(51374061,51074040)supported by the National Natural Science Foundation of ChinaProject(201202064)supported by the Natural Science Foundation of Liaoning Province,ChinaProject(N120402004)supported by the Fundamental Research Funds for the Central Universities,China
文摘Vanadium extraction of vanadium-bearing titanomagnetite was investigated by selective chlorination. Thermodynamics analyses on the interactive reactions among related species in the system were made before the experiments. Some fundamental experiments for extracting vanadium by FeClx as chlorinating agent were conducted over the temperature range of 900-1300 K under air or oxygen atmosphere. The results show that vanadium can be extracted by the selective chlorination, using FeClx, based on thermodynamic analysis and experiment. Vanadium extraction ratio first increases with the increase of temperature, and then decreases with the increase of temperature over the range of 900-1300 K under air or oxygen atmosphere. The higher molar ratio of FeCI3 to oxides （nchl：noxd） reacting with FeC13, the higher ratio of vanadium extraction. Under oxygen atmosphere, the vanadium extraction ratio is up to 32% at 1100 K for 2 h by using FeCI3 as chlorinating agent.
基金Project supported by China Baowu Low Carbon Metallurgy Innovation Foundation(BWLCF202121)Jiangxi Provincial Key Laboratory of Flash Green Development and Recycling(20193BCD40019)+1 种基金Academic and Technical Leaders of Major Disciplines in Jiangxi Province(20213BCJ22003)Yichun Science and Technology Plan Project(2023YBKJGG04)。
文摘Due to the lack of effective screening systems in the rare earth waste recycling industry,the composition of rare earth elements in rare earth waste is complex and difficult to separate.In response to such problems,by studying the reaction behavior between various elements in rare earth waste and cobalt chloride,we propose a process path for the separation and recovery of iron,cerium and other rare earth elements using cobalt chloride roasting.The experiments on simulated wastes show that the leaching rates of the Nd,Sm,Gd,Pr can reach 98.31%,94.5%,93.87%and 72.05%under the optimal process conditions,respectively.Ce and iron remain in the leaching residue in the form of CeO_(2)and CoFe_(2)O_(4),respectively.And through a simple magnetic separation process,CeO_(2)and CoFe_(2)O_(4)can be enriched in non-magnetic leaching residue and magnetic leaching residue,respectively.The cerium content in the leaching residue composed of cobalt ferrite is only 1.95%.Therefore,this method is beneficial to the separation and high-value utilization of iron,cerium,and other rare earth elements in the waste system.The research results can provide theoretical reference for the low-cost and high-value recovery of rare earth secondary resources.
