熔盐中稀土元素高效精准分离与回收工艺

Hang Hua; Kouji Yasuda; Yutaro Norikawa; Toshiyuki Nohira

doi:10.1016/j.eng.2022.12.013

PDF(1849 KB)

工程（英文） ›› 2025, Vol. 45 ›› Issue (2) : 165-173. DOI: 10.1016/j.eng.2022.12.013

研究论文

Article

熔盐中稀土元素高效精准分离与回收工艺

作者信息 +

Highly Efficient and Precise Rare-Earth Elements Separation and Recycling Process in Molten Salt

Author information +

History +

Abstract

Owing to the worldwide trend towards carbon neutrality, the number of Dy-containing heat-resistant Nd magnets used for wind power generation and electric vehicles is expected to increase exponentially. However, rare earth (RE) elements (especially Dy) are unevenly distributed globally. Therefore, an environmental-friendly recycling method for RE elements with a highly precise separation of Dy and Nd from end-of-life magnets is required to realize a carbon-neutral society. As an alternative to traditional hydrometallurgical RE separation techniques with a high environmental load, we designed a novel, highly efficient, and precise process for the separation and recycling of RE elements from magnet scrap. As a result, over 90% of the RE elements were efficiently extracted from the magnets using MgCl₂ and evaporation loss was selectively suppressed by adding CaF₂. The extracted RE elements were electrolytically separated based on the formation potential differences of the RE alloys. Nd and Dy metals with purities greater than 90% were estimated to be recovered at rates of 96% and 91%, respectively. Almost all the RE in the scraps could be separated and recycled as RE metals, and the byproducts were easily removed. Thus, this process is expected to be used on an industrial scale to realize a carbon-neutral society.

Keywords

Neodymium magnet scrap / Rare-earth separation / Dysprosium / Molten salt / Electrochemical formation

引用本文

EndNote

Ris (Procite)

Bibtex

导出引用

Hang Hua, Kouji Yasuda, Yutaro Norikawa. 熔盐中稀土元素高效精准分离与回收工艺. Engineering. 2025, 45(2): 165-173 https://doi.org/10.1016/j.eng.2022.12.013

参考文献

原文顺序 | 文献年度倒序 | 文中引用次数倒序

[1]	Jones N.Materials science: the pull of stronger magnets.Nature 2011; 472(7341):22-23.
[2]	Coey JMD.Permanent magnet applications.J Magn Magn Mater 2002; 248(3):441-456.
[3]	Hirosawa S, Matsuura Y, Yamamoto H, Fujimura S, Sagawa M, Yamauchi H.Magnetization and magnetic anisotropy of R₂Fe₁₄B measured on single crystals.J Appl Phys 1986; 59(3):873-879.
[4]	Sagawa M, Hirosawa S, Yamamoto H, Fujimura S, Matsuura Y.Nd–Fe–B permanent magnet materials.Jpn J Appl Phys 1987; 26(6R):785-800.
[5]	US Geological Survey.Mineral commodity summaries 2021. US Geological Survey, Reston (2021)
[6]	Shiratori T, Nakamura T.Concept of artificial mineral deposit—a proposal for employing the concept of “reserve to stock”.Shigen-to-Sozai 2006; 122(6–7):325-329.
[7]	Kramer D.US government acts to reduce dependence on China for rare-earth magnets.Phys Today 2021; 74(2):20-24.
[8]	Xiao W, Pan D, Niu Z, Fan Y, Wu S, Wu W.Opportunities and challenges of high-pressure ion exchange chromatography for nuclide separation and enrichment.Chin Chem Lett 2022; 33(7):3413-3421.
[9]	Xiao J, Li B, Qiang R, Qiu H, Chen J.Highly selective adsorption of rare earth elements by honeycomb-shaped covalent organic frameworks synthesized in deep eutectic solvents.Environ Res 2022; 214:113977.
[10]	Chen Z, Li Z, Chen J, Kallem P, Banat F, Qiu H.Recent advances in selective separation technologies of rare earth elements: a review.J Environ Chem Eng 2022; 10(1):107104.
[11]	Adachi G, Murase K, Shinozaki K, Machida K.Mutual separation characteristics for lanthanoid elements via gas phase complexes with alkaline chlorides.Chem Lett 1992; 21(4):511-514.
[12]	Murase K, Shinozaki K, Hirashima Y, Machida K, Adachi G.Rare earth separation using a chemical vapor transport process mediated by vapor complexes of the LnCl₃–AlCl₃ system.J Alloys Compd 1993; 198(1–2):31-38.
[13]	Murase K, Machida K, Adachi G.Recovery of rare metals from scrap of rare earth intermetallic material by chemical vapor transport.J Alloys Compd 1995; 217(2):218-225.
[14]	Murase K, Ozaki T, Machida K, Adachi G.Extraction and mutual separation of rare earths from concentrates and crude oxides using chemical vapor transport.J Alloys Compd 1996; 233(1–2):96-106.
[15]	Ozaki T, Jiang J, Murase K, Machida K, Adachi G.Mutual separation characteristics for the yttrium and lanthanides with chemical vapor transport process mediated by metal chloride gaseous complexes.J Alloys Compd 1998; 265(1–2):125-131.
[16]	Uda T, Jacob KT, Hirasawa M.Technique for enhanced rare earth separation.Science 2000; 289(5488):2326-2329.
[17]	Uda T, Komarov S, Hirasawa M.Dry separation for rare earth by vacuum distillation of di and triiodide mixture.Mater Trans 2001; 42(8):1813-1819.
[18]	Xu Y, Chumbley LS, Laabs FC.Liquid metal extraction of Nd from NdFeB magnet scrap.J Mater Res 2000; 15(11):2296-2304.
[19]	Uda T.Recovery of rare earths from magnet sludge by FeCl₂.Mater Trans 2002; 43(1):55-62.
[20]	Okabe TH, Takeda O, Fukuda K, Umetsu Y.Direct extraction and recovery of neodymium metal from magnet scrap.Mater Trans 2003; 44(4):798-801.
[21]	Saito T, Sato H, Ozawa S, Yu J, Motegi T.The extraction of Nd from waste Nd–Fe–B alloys by the glass slag method.J Alloys Compd 2003; 353(1–2):189-193.
[22]	Takeda O, Okabe TH, Umetsu Y.Phase equilibrium of the system Ag–Fe–Nd, and Nd extraction from magnet scraps using molten silver.J Alloys Compd 2004; 379(1–2):305-313.
[23]	Itoh M, Masuda M, Suzuki S, Machida KI.Recycling of rare earth sintered magnets as isotropic bonded magnets by melt-spinning.J Alloys Compd 2004; 374(1–2):393-396.
[24]	Takeda O, Okabe TH, Umetsu Y.Recovery of neodymium from a mixture of magnet scrap and other scrap.J Alloys Compd, 408–412 2006; 387-390.
[25]	Itoh M, Miura K, Machida K.Novel rare earth recovery process on Nd–Fe–B magnet scrap by selective chlorination using NH₄Cl.J Alloys Compd 2009; 477(1–2):484-487.
[26]	Takeda O, Nakano K, Sato Y.Recycling of rare earth magnet waste by removing rare earth oxide with molten fluoride.Mater Trans 2014; 55(2):334-341.
[27]	Chae HJ, Kim YD, Kim BS, Kim JG, Kim TS.Experimental investigation of diffusion behavior between molten Mg and Nd–Fe–B magnets.J Alloys Compd 2014; 586(Suppl 1):S143-S149.
[28]	Akahori T, Miyamoto Y, Saeki T, Okamoto M, Okabe TH.Optimum conditions for extracting rare earth metals from waste magnets by using molten magnesium.J Alloys Compd 2017; 703:337-343.
[29]	Shirayama S, Okabe TH.Selective extraction and recovery of Nd and Dy from Nd–Fe–B magnet scrap by utilizing molten MgCl₂.Metall Mater Trans B 2018; 49(3):1067-1077.
[30]	Oishi T, Konishi H, Nohira T, Tanaka M, Usui T.Separation and recovery of rare earth metals by molten salt electrolysis using alloy diaphragm.Kagaku Kogaku Ronbunshu 2010; 36(4):299-303.
[31]	Konishi H, Ono H, Nohira T, Oishi T.Separation of Dy and Nd (La) using molten salt and an alloy diaphragm.ECS Trans 2013; 50(11):463-472.
[32]	Nohira T, Kobayashi S, Kondo K, Yasuda K, Hagiwara R, Oishi T, et al.Electrochemical formation of RE–Ni (RE = Pr, Nd, Dy) alloys in molten halides.ECS Trans 2013; 50(11):473-482.
[33]	Yasuda K, Kondo K, Kobayashi S, Nohira T, Hagiwara R.Selective formation of rare-earth–nickel alloys via electrochemical reactions in NaCl–KCl molten salt.J Electrochem Soc 2016; 163(5):D140-D145.
[34]	Hua H, Yasuda K, Konishi H, Nohira T.Electrochemical formation of Dy–Ni alloys in molten CaCl₂–DyCl₃.J Electrochem Soc 2020; 167(14):142504.
[35]	Hua H, Yasuda K, Konishi H, Nohira T.Electrochemical formation of Nd–Ni alloys in molten CaCl₂–NdCl₃.J Electrochem Soc 2021; 168(3):032506.
[36]	Hua H, Yasuda K, Nohira T.Highly efficient and precise electrolysis separation of dysprosium from neodymium for magnet scrap recycling in molten salt.ACS Sustain Chem Eng 2022; 10(28):9225-9231.
[37]	HSC Chemistry®.Version 9 [software]. Pori: Outotec Information Center; 2015.