Recycled Nd-Fe-B sintered magnets prepared from sludges by calcium reduction-diffusion process
来源期刊：JOURNAL OF RARE EARTHS2018年第12期
论文作者：Xiaowen Yin Min Liu Baicen Wan Yu Zhang Weiqiang Liu Yufeng Wu Dongtao Zhang Ming Yue
文章页码：1284 - 1291
摘 要：Environmental friendly recycling process for Nd-Fe-B sintered magnet sludges generated in the manufacturing process, which contain large amount of rare earth, including Nd, Pr and Dy, is badly needed so far. In present study, we have developed an effective route to obtain recycled sintered magnets from Nd-Fe-B sintered magnet sludges by calcium reduction-diffusion（RD） process. Compared to conventional recycling process, our research is focused on recovering most of the useful elements, including Nd, Pr, Dy, Co, and Fe together instead of just rare earth elements. To improve the recycling efficiency and reduce pollution, the co-precipitating parameters were simulated and calculated using MATLAB software. Most of useful elements were recovered by a co-precipitation method, and the obtained composite powders were then directly fabricated as recycled Nd-Fe-B powders by a calcium reduction-diffusion（RD） method. The recovery rates are 98%, 99%, 99%, 93%, and 99%, for Nd, Pr, Dy, Co, and Fe, respectively. The amount of useful elements contained in the recovered composite powders is greater than99.71 wt%. The process of RD for synthesizing Nd2 Fe14B and subsequently removing CaO was thoroughly investigated. Furthermore, the recycled Nd-Fe-B magnet exhibits a remanence of 1.1 T, a coercivity of1053 kA/m, and an energy product of 235.6 kJ/m3, respectively, indicating that recycled Nd-Fe-B sintered magnet was successfully recovered from the severely contaminated sludges via an effective recycling route.
Xiaowen Yin1，Min Liu1，Baicen Wan1，Yu Zhang1，Weiqiang Liu1，Yufeng Wu2，Dongtao Zhang1，Ming Yue1
1. College of Materials Science and Engineering,Beijing University of Technology2. Institute of Circular Economy,Beijing University of Technology
摘 要：Environmental friendly recycling process for Nd-Fe-B sintered magnet sludges generated in the manufacturing process, which contain large amount of rare earth, including Nd, Pr and Dy, is badly needed so far. In present study, we have developed an effective route to obtain recycled sintered magnets from Nd-Fe-B sintered magnet sludges by calcium reduction-diffusion（RD） process. Compared to conventional recycling process, our research is focused on recovering most of the useful elements, including Nd, Pr, Dy, Co, and Fe together instead of just rare earth elements. To improve the recycling efficiency and reduce pollution, the co-precipitating parameters were simulated and calculated using MATLAB software. Most of useful elements were recovered by a co-precipitation method, and the obtained composite powders were then directly fabricated as recycled Nd-Fe-B powders by a calcium reduction-diffusion（RD） method. The recovery rates are 98%, 99%, 99%, 93%, and 99%, for Nd, Pr, Dy, Co, and Fe, respectively. The amount of useful elements contained in the recovered composite powders is greater than99.71 wt%. The process of RD for synthesizing Nd2 Fe14B and subsequently removing CaO was thoroughly investigated. Furthermore, the recycled Nd-Fe-B magnet exhibits a remanence of 1.1 T, a coercivity of1053 kA/m, and an energy product of 235.6 kJ/m3, respectively, indicating that recycled Nd-Fe-B sintered magnet was successfully recovered from the severely contaminated sludges via an effective recycling route.
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