Recovery of rare earths from sludges containing rare-earth elements

Saito, Tetsuji; Sato, Hiroo; Motegi, Tetsuichi

doi:10.1016/j.jallcom.2006.01.011

Cited by 60 publications

(30 citation statements)

References 7 publications

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“…Rare earth elements (REEs), including Lanthanide elements as well as yttrium and scandium, are widely used in various high-tech applications, such as high strength permanent magnets, automotive catalytic converters, lasers, electronic devices, and superconductors [1][2][3][4][5][6]. As a member of the rare earth family, neodymium (Nd) gains great attention due to high demand in the Nd-Fe-B magnet industry, especially in high performance electric motors in hybrid electric vehicles and direct-drive wind turbine generators [7].…”

Section: Introductionmentioning

confidence: 99%

Selective and fast recovery of neodymium from seawater by magnetic iron oxide Fe3O4

You

2015

Chemical Engineering Journal

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Section: Introductionmentioning

confidence: 99%

Selective and fast recovery of neodymium from seawater by magnetic iron oxide Fe3O4

You

2015

Chemical Engineering Journal

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“…The concentrations of REs (neodymium, dysprosium, and praseodymium) in the iron alloy were lowered to less than 0.01 mass %, and almost all REs were extracted into the slag phase. The REs could be recovered from the slag by dissolving the slag in sulfuric acid followed by selective precipitation of the REs as a sulfate double salt or hydroxide [68]. The oxides could also be leached with hydrochloric acid and precipitated as an oxalate.…”

Section: Separation Of Re As Reos From Oxidized Magnet Wastementioning

confidence: 99%

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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“…The process steps include leaching in strong acid, the selective precipitation of REEs as double sulfates, oxalates or fluorides, REEs purification processes, and the synthesis of REEs compounds and metals [7]. Saito et al investigated the complete dissolution of NdFeB alloy and selective precipitation of sodium neodymium sulfates [8]. Itakura et al reported the hydrothermal treatment of Ni-coated NdFeB magnets in a mixture of HCl and oxalic acid solutions at 110…”

Section: Introductionmentioning

confidence: 99%

Novel Extraction Process Of Rare Earth Elements From NdFeB Powders Via Alkaline Treatment

Chung

Kim

Yoon

2015

Archives of Metallurgy and Materials

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The alkaline treatment of NdFeB powders in NaOH solution at various equivalent amounts of NaOH at 100• C was performed. The resultant powders were then leached in 0.5M H 2 SO 4 solution at 25• C for 2 minutes. At 5 equivalents of NaOH, neodymium in NdFeB powders was partially transformed to neodymium hydroxide. The transformation of neodymium to neodymium hydroxide actually occurred at 10 equivalents of NaOH and was facilitated by increasing the equivalent of NaOH from 10 to 30. In addition, iron was partially transformed to magnetite during the alkaline treatment, which was also promoted at a higher equivalent of NaOH. The leaching yield of neodymium from alkaline-treated powders was increased with an increasing equivalent of NaOH up to 10; however, it slightly decreased with the equivalent NaOH of over 10. The leaching yield of iron was inversely proportional to that of rare earth elements. NdFeB powders treated at 10 equivalents of NaOH showed a maximum leaching yield of neodymium and dysprosium of 91.6% and 94.6%, respectively, and the lowest leaching yield of iron of 24.2%, resulting in the highest selective leaching efficiency of 69.4%.

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Recovery of rare earths from sludges containing rare-earth elements

Cited by 60 publications

References 7 publications

Selective and fast recovery of neodymium from seawater by magnetic iron oxide Fe3O4

Selective and fast recovery of neodymium from seawater by magnetic iron oxide Fe3O4

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

Novel Extraction Process Of Rare Earth Elements From NdFeB Powders Via Alkaline Treatment

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