Recycling of Rare Earth Magnet Waste by Removing Rare Earth Oxide with Molten Fluoride

Takeda, Osamu; Nakano, Kiyotaka; Sato, Yuzuru

doi:10.2320/matertrans.m-m2013836

Cited by 35 publications

(28 citation statements)

References 21 publications

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“…Various research groups are working on this topic [14][15][16][17][18]. Extraction processes are promising in that they are generally suitable to handle NdFeB scrap with variable compositions and contamination levels [19,20]. Since the electrolyte is reusable and the processing chain short, the recycling process is also expected to be environmentally beneficial over longer processing routes [13,20].…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

An Ex-ante LCA Study of Rare Earth Extraction from NdFeB Magnet Scrap Using Molten Salt Electrolysis

Schulze

Abbasalizadeh

Bulach³

et al. 2018

J. Sustain. Metall.

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A new recycling process for the extraction of rare earths from neodymium-iron-boron (NdFeB) magnet scrap is being developed, based on the direct extraction of rare earths from end-of-life magnet material in a molten fluoride electrolysis bath. Rare earths are required in their metallic form for the production of new NdFeB magnets, and the suggested process achieves this through a single step. The process is being developed on a laboratory scale and has been proven to work in principle. It is expected to be environmentally beneficial when compared to longer processing routes. Conducting life cycle assessment at R&D stage can provide valuable information to help steer process development into an environmentally favorable direction. We conducted a life cycle assessment study to provide a quantitative estimate of the impacts associated with the process being developed and to compare the prospective impacts against those of the current state-of-the-art technology. The comparison of this recycling route with primary production shows that the recycling process has the potential for much lower process-specific impacts when compared against the current rare earth primary production route. The study also highlights that perfluorocarbon emissions, which occur during primary rare earth production, warrant further investigation. Keywords Rare earths Á Molten salt electrolysis Á Molten fluorides Á Recycling Á Ex-ante LCA Á Perfluorocarbon (PFC) emissions

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Section: Electronic Supplementary Materialsmentioning

confidence: 99%

An Ex-ante LCA Study of Rare Earth Extraction from NdFeB Magnet Scrap Using Molten Salt Electrolysis

Schulze

Abbasalizadeh

Bulach³

et al. 2018

J. Sustain. Metall.

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“…Table 2 summarizes in more detail the process conditions, the reagents, and the products of various high-temperature recycling routes of REPM. As described by Takeda et al [28], the extraction type recycling is suitable for waste heavily contaminated with oxygen, such as swarf generated in cutting process. The advantages are that pure RE metal can be obtained by separation of REEs from the waste, and heavily concentrated impurities can be removed.…”

Section: Repm Recycling Strategies and Pyrometallurgical Routesmentioning

confidence: 99%

“…4, the two widely known oxidation routes are Nos. 6 and 8, developed, respectively, by Saguchi et al [37] and by Takeda et al [28]. As summarized in Tables 1 and 2, the former removes oxygen using calciothermic reduction to reduce REOs without melting the magnet, while the latter uses flux to extract REOs from the waste to recover Nd-Fe-B alloy.…”

Section: Recycling or Recovery Via Oxidationmentioning

confidence: 99%

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Review of High-Temperature Recovery of Rare Earth (Nd/Dy) from Magnet Waste

Firdaus

Rhamdhani

Durandet

et al. 2016

J. Sustain. Metall.

108

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Rare-earth metals, particularly neodymium, dysprosium, and praseodymium are becoming increasingly important in the transition to a green economy due to their essential role in permanent magnet applications such as in electric motors and generators. With the increasingly limited rare-earth supply and complexity of processing Nd, Dy, and Pr from primary ores, recycling of rare-earth based magnets has become a necessary option to manage supply and demand. Depending on the form of the starting material (sludge or scrap), there are different routes that can be used to recover neodymium from secondary sources, ranging from hydrometallurgical (based on its primary production process), electrochemical to pyrometallurgical. Pyrometallurgical routes provide solution in cases where water is scarce and generation of waste is to be limited. This paper presents a systematic review of previous studies on the high-temperature (pyrometallurgical) recovery of rare earths from magnets. The features and conditions at which the recycling processes had been studied are mapped and evaluated technically. The review also highlights the reaction mechanisms, behaviors of the rare-earth elements, and the formation of intermediate compounds in high-temperature recycling processes. Recommendations for further scientific research to enable the development of recovery of the rare-earth and magnet recycling are also presented.

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“…In recent years, many neodymium magnets have been wasted with disposal of these products. Thus, recovery processes for rare earth elements from neodymium magnets have been developed, such as hydrometallurgical treatment [1][2][3], hydrothermal processing [4], molten metal extraction [5][6][7][8], molten salt extraction [9], chloride volatility processing [10], and glass slag processing [11]. The rare earth oxides are collected from these processes, and these oxides have to be reduced to rare earth metal using molten salt electrolysis.…”

Section: Introductionmentioning

confidence: 99%

Leaching of Rare Earth Elements from Neodymium magnet using Electrochemical method

Kamimoto

Yoshimura

Itoh

et al. 2015

Trans. Mat. Res. Soc. Japan

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Neodymium magnets contain rare earth elements. In this study, rare earth elements were recovered from neodymium magnets using the molten salt electrolysis process, thereby making the existing recycling processes for neodymium magnets obsolete. Using anodic polarization, rare earth elements were leached by controlled potential electrolysis, without leaching iron and other elements. The composition of rare earth elements in the molten salt was more than 99 mass% from the controlled potential electrolysis process, not accounting for the molten salt component. Rare earth elements were leached from the boundary phase first. After electrolysis, the boundary phase disappeared from the residual, and rare earth elements were not detected in the residual. The Nd2Fe14B alloy was converted to other materials. The neodymium magnet decomposed with the leaching of the boundary phase and became brittle. It was shown that rare earth elements were leached in preference to other elements using controlled potential electrolysis

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Recycling of Rare Earth Magnet Waste by Removing Rare Earth Oxide with Molten Fluoride

Cited by 35 publications

References 21 publications

An Ex-ante LCA Study of Rare Earth Extraction from NdFeB Magnet Scrap Using Molten Salt Electrolysis

An Ex-ante LCA Study of Rare Earth Extraction from NdFeB Magnet Scrap Using Molten Salt Electrolysis

Review of High-Temperature Recovery of Rare Earth (Nd/Dy) from Magnet Waste

Leaching of Rare Earth Elements from Neodymium magnet using Electrochemical method

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