Improved room-temperature-selectivity between Nd and Fe in Nd recovery from Nd-Fe-B magnet

Kataoka, Yusuke; Ono, Taisuke; Tsubota, Masami; Kitagawa, Jiro

doi:10.1063/1.4935570

Cited by 16 publications

(12 citation statements)

References 9 publications

(12 reference statements)

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“…This is marked improvement over other selective leaching processes which required 5-7 days for complete extraction of REEs. 21,36 Prolonging the reaction time further decreased the extraction of REEs due to possible precipitation of REEs as hydroxides due to migration of hydroxide ions from the catholyte (eqn. 8).…”

Section: 32mentioning

confidence: 99%

Selective electrochemical extraction of REEs from NdFeB magnet waste at room temperature

et al. 2018

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Section: 32mentioning

confidence: 99%

Selective electrochemical extraction of REEs from NdFeB magnet waste at room temperature

et al. 2018

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“…In the acid leaching method for sludge [15], it is also necessary to heat the acid solution up to 80°C. We have recently proposed a pretreatment of corrosion [16] before the HCl leaching and the oxalic acid precipitation. In this method, the recovery ratio of Nd reaches 97% even when a room temperature process is used.…”

Section: Introductionmentioning

confidence: 99%

Rare Earth Extraction from NdFeB Magnets

Kitagawa¹,

Tsubota²

2018

Noble and Precious Metals - Properties, Nanoscale Effects and Applications

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There is a considerable interest in the extraction of rare earths (RE) from NdFeB magnets in order to recycle rare earth elements. Although the wet process using acid is in practical use in the in-plant recycle of sludge, higher selectivity between rare earths and Fe at room temperature is desired. We have recently proposed a pretreatment of corrosion before the hydrochloric acid (HCl) leaching and the oxalic acid precipitation. Almost full recovery of rare earths can be achieved even at room temperature process. In practical extraction methods, employing wet processes, the discharge of waste acid solution is a problem that needs to be solved to reduce the environmental impact. We further present an encouraging demonstration of rare earth extraction from NdFeB magnet using a closed-loop HClbased process. Triple extraction has been conducted, and the recovery ratio of rare earths is approximately 50% in each extraction, which is reduced from almost 100% recovery in a one-shot extraction. Despite the reduced extraction efficiency, our method with a rather small number of procedures at almost room temperature is still highly advantageous in terms of cost and environmental friendliness. This study represents the initial step toward the realization of a closed-loop acid process in the recycling of rare earth elements.

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“…In the acid leaching method for sludge treatment 10 , it is also necessary to heat the acid solution to 80 °C. We have recently proposed a pretreatment involving corrosion of the magnet 11 before dissolution in HCl and the oxalic acid precipitation process. The Nd recovery ratio in this process reaches 97%, even when a room temperature process is used, which represents the major advance of this method.…”

Section: Introductionmentioning

confidence: 99%

Rare Earth Extraction from NdFeB Magnet Using a Closed-Loop Acid Process

Kitagawa

Uemura

2017

Sci Rep

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There is considerable interest in extraction of rare earth elements from NdFeB magnets to enable recycling of these elements. In practical extraction methods using wet processes, the acid waste solution discharge is a problem that must be resolved to reduce the environmental impact of the process. Here, we present an encouraging demonstration of rare earth element extraction from a NdFeB magnet using a closed-loop hydrochloric acid (HCl)-based process. The extraction method is based on corrosion of the magnet in a pretreatment stage and a subsequent ionic liquid technique for Fe extraction from the HCl solution. The rare earth elements are then precipitated using oxalic acid. Triple extraction has been conducted and the recovery ratio of the rare earth elements from the solution is approximately 50% for each extraction process, as compared to almost 100% recovery when using a one-shot extraction process without the ionic liquid but with sufficient oxalic acid. Despite its reduced extraction efficiency, the proposed method with its small number of procedures at almost room temperature is still highly advantageous in terms of both cost and environmental friendliness. This study represents an initial step towards realization of a closed-loop acid process for recycling of rare earth elements.

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Improved room-temperature-selectivity between Nd and Fe in Nd recovery from Nd-Fe-B magnet

Cited by 16 publications

References 9 publications

Selective electrochemical extraction of REEs from NdFeB magnet waste at room temperature

Selective electrochemical extraction of REEs from NdFeB magnet waste at room temperature

Rare Earth Extraction from NdFeB Magnets

Rare Earth Extraction from NdFeB Magnet Using a Closed-Loop Acid Process

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