An Efficient Process for Recycling Nd-Fe-B Sludge as High-Performance Sintered Magnets  

作　　者：Xiaowen Yin Ming Yue Qingmei Lu Min Liu Feng Wang Yubing Qiu Weiqiang Liu Tieyong Zuo Shanshun Zha Xuliang Li Xiaofei Yi 

机构地区：[1]College of Materials Science and Engineering,Beijing University of Technology,Beijing 100124,China [2]State Key Laboratory of Rare Earth Permanent Magnetic Materials,Hefei 231500,China [3]Key Laboratory of Advanced Functional Materials,Ministry of Education,Beijing University of Technology,Beijing 100124,China [4]Earth-Panda Advanced Magnetic Materials Co.,Ltd.,Hefei 231500,China

出　　处：《Engineering》2020年第2期165-172,共8页工程（英文）

基　　金：financially supported by the National High Technology Research and Development Program of China(2012AA063201);the Beijing Municipal Natural Science Foundation(2172012);the State Key Laboratory of Rare Earth Permanent Magnetic Materials Opening Foundation(SKLREPM17OF02).

摘　　要：Given the increasing concern regarding the global decline in rare earth reserves and the environmental burden from current wet-process recycling techniques,it is urgent to develop an efficient recycling technique for leftover sludge from the manufacturing process of neodymium-iron-boron(Nd-Fe-B)sintered magnets.In the present study,centerless grinding sludge from the Nd-Fe-B sintered magnet machining process was selected as the starting material.The sludge was subjected to a reduction-diffusion(RD)process in order to synthesize recycled neodymium magnet(Nd2Fe14B)powder;during this process,most of the valuable elements,including neodymium(Nd),praseodymium(Pr),gadolinium(Gd),dysprosium(Dy),holmium(Ho),and cobalt(Co),were recovered simultaneously.Calcium chloride(CaCl2)powder with a lower melting point was introduced into the RD process to reduce recycling cost and improve recycling efficiency.The mechanism of the reactions was investigated systematically by adjusting the reaction temperature and calcium/sludge weight ratio.It was found that single-phase Nd2Fe14B particles with good crystallinity were obtained when the calcium weight ratio(calcium/sludge)and reaction temperature were 40 wt% and 1050℃,respectively.The recovered Nd2Fe14B particles were blended with 37.7 wt% Nd4Fe14B powder to fabricate Nd-Fe-B sintered magnets with a remanence of 12.1 kG(1 G=1×10^-4T),and a coercivity of 14.6 kOe(1 Oe=79.6A·m^-1),resulting in an energy product of 34.5 MGOe.This recycling route promises a great advantage in recycling efficiency as well as in cost.

关 键 词：ND-FE-B GRINDING SLUDGE Recycled sintered MAGNETS CALCIUM reduction-diffusion Rare-earth-rich alloy doping 

分 类 号：X705[环境科学与工程—环境工程] TM27[一般工业技术—材料科学与工程]