Separation of Neodymium and Dysprosium by Molten Salt Electrolysis Using an Alloy Diaphragm

Oishi, Tadashi; Yaguchi, Miki; Katasho, Yumi

doi:10.1007/978-3-030-36758-9_14

Cited by 7 publications

(12 citation statements)

References 7 publications

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“…Permeation experiment.-Figure 3 shows the experimental setup for the permeation experiment, which is basically the same as that described previously. 11 High-purity alumina was used as the cell material. A Ni film was employed as the starting material of the alloy diaphragm because Ni easily alloys with REEs in molten salts and the RE-Ni alloying/de-alloying phenomena were already extensively investigated by our group.…”

Section: Methodsmentioning

confidence: 99%

“…indispensable because Dy is the most valuable and scarce element among those used in Nd-Fe-B magnets. Although the selective Dy permeation has already been reported, 11 the evaluated current efficiency was quite low (less than 20%) because of the dendritic deposition and drop-off of RE metals from the cathode. Therefore, this experimental method was modified herein to prevent dendrite formation and to accurately evaluate the selectivity.…”

mentioning

confidence: 95%

“…Based on this background, a simple, economical, and environmentally sound REE recycling process was proposed and investigated, [7][8][9][10][11] as shown in Fig. 1.…”

mentioning

confidence: 99%

“…In fact, the authors recently reported the selective permeation of Dy through a RE-Ni alloy diaphragm in LiCl-KCl eutectic melts containing NdCl 3 and DyCl 3 at 450 °C. 11 Here, if sufficient selectivity and adequate reaction rates are achieved, the direct recovery of Nd and Dy from Nd-Fe-B magnet scraps will be realized.…”

mentioning

confidence: 99%

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Selective Permeation of Dysprosium Through an Alloy Diaphragm in Molten Chloride Systems

Oishi

Yaguchi

Katasho

et al. 2020

J. Electrochem. Soc.

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To develop a new separation technique for rare earth (RE) elements based on alloy diaphragms and molten salt electrolysis, a permeation experiment was conducted in LiCl–KCl eutectic melts containing RECl3 (RE = Dy, Nd, and La, 0.5 mol%) at 450 °C. In this technique, the alloy diaphragm functions as a bipolar electrode and RE ions permeate via three steps: (a) reduction of RE ions to form alloys on the anolyte side of the diaphragm, (b) diffusion of RE atoms in the diaphragm, and (c) oxidation of RE atoms to dissolve into the catholyte on the other side of the diaphragm. The experiment indicated that Dy selectively permeated through the alloy diaphragm consisting of RENi2. The permeated Dy/Nd molar ratio was ∼5, which was mainly determined by the selective alloy formation on the anolyte side of the diaphragm. However, the obtained Dy/Nd ratio was lower than that suggested by the preliminary experiment, in which a Ni substrate was simply alloyed in a LiCl–KCl–NdCl3–DyCl3 melt. Scanning electron microscopy observation and energy dispersive X-ray analysis of the diaphragm revealed that the lower selectivity compared to the preliminary experiment was attributable to the high diffusion rate of Nd atoms inside the alloy diaphragm.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 95%

“…Based on this background, a simple, economical, and environmentally sound REE recycling process was proposed and investigated, [7][8][9][10][11] as shown in Fig. 1.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Selective Permeation of Dysprosium Through an Alloy Diaphragm in Molten Chloride Systems

Oishi

Yaguchi

Katasho

et al. 2020

J. Electrochem. Soc.

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“…In addition, LiCl-KCl melts are more suitable for the separation of REEs than NaCl-KCl and LiF-CaF 2 systems. Basing from the research of "bifunctional" electrode for the separation of REEs, Ito et al [122] simulated the extraction and separation of REEs. The simulation process shows less iterative operations and requires high purity.…”

Section: Summary Of Separation/recovery Of Reesmentioning

confidence: 99%

Recovery and separation of rare earth elements by molten salt electrolysis

Yin

Xue

Yan

et al. 2021

Int J Miner Metall Mater

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With the increasing demand of rare earth metals in functional materials, recovery of rare earth elements (REEs) from secondary resources has become important for the green economy transition. Molten salt electrolysis has the advantages of low water consumption and low hazardous waste during REE recovery. This review systematically summarizes the separation and electroextraction of REEs on various reactive electrodes in different molten salts. It also highlights the relationship between the formed alloy phases and electrodeposition parameters, including applied potential, current, and ion concentration. Moreover, the feasibility of using LiF-NaF-KF electrolyte to recover REEs is evaluated through thermodynamic analysis. Problems related to REE separation/recovery the choice of electrolyte are discussed in detail to realize the low-energy and high current efficiency of practical applications.

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Selective Permeation of Neodymium Through an Alloy Diaphragm in Molten Chloride Systems

Oishi¹,

Yaguchi²,

Katasho³

2020

ECS Trans.

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As part of an ongoing study of a new recycling process for Nd-Fe-B permanent magnets, selective permeation of Nd through an RE-Ni (RE=Nd and Dy) alloy diaphragm was investigated in LiCl-KCl eutectic melts containing NdCl3 and DyCl3 or LaCl3 at 450°C. Selective permeation of Nd was achieved by controlling the potential of the alloy diaphragm, which functions as a bipolar electrode. Interestingly, EDX analysis revealed that the molar ratio of Nd/Dy in the alloy diaphragm was less than 0.05, which is two orders of magnitude lower than that of the permeated amount. These results suggest that the transportation rate of Nd atoms in the alloy diaphragm was extremely high compared to that of Dy. In order to obtain further insight into the transportation mechanism of RE atoms in the alloy diaphragm, STEM observations were also carried out. The results suggested that the transportation of RE atoms cannot be explained by simple grain boundary diffusion.

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Separation of Neodymium and Dysprosium by Molten Salt Electrolysis Using an Alloy Diaphragm

Cited by 7 publications

References 7 publications

Selective Permeation of Dysprosium Through an Alloy Diaphragm in Molten Chloride Systems

Selective Permeation of Dysprosium Through an Alloy Diaphragm in Molten Chloride Systems

Recovery and separation of rare earth elements by molten salt electrolysis

Selective Permeation of Neodymium Through an Alloy Diaphragm in Molten Chloride Systems

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