Technique for recovering rare-earth metals from spent sintered Nd-Fe-B magnets without external heating

Sasai, Ryo; Shimamura, Naohiro

doi:10.1016/j.jascer.2016.01.009

Cited by 19 publications

(12 citation statements)

References 15 publications

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“…1 During the last years, the environmental and economic benets of NdFeB magnet recycling have been discussed, analyzed and investigated. 2,3 Diverse methodologies have been proposed, including the use of mechano-chemical treatment without external heating, 4 the recovery of neodymium from NdFeB magnets at high temperatures using molten magnesium metal as extractant 5 and hydrogen gas to separate the NdFeB magnets from waste. [6][7][8][9] As an alternative to these processes, rare earths and other valuable metals present in magnet scrap can be recovered and puried through leaching and solvent extraction.…”

Section: Introductionmentioning

confidence: 99%

Separation of rare earths and other valuable metals from deep-eutectic solvents: a new alternative for the recycling of used NdFeB magnets

et al. 2017

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Section: Introductionmentioning

confidence: 99%

Separation of rare earths and other valuable metals from deep-eutectic solvents: a new alternative for the recycling of used NdFeB magnets

et al. 2017

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“…This approach exhibited a high removal rate (99.6%) of total Fe in the recycling of rare metals from the rare earth-bearing scrap. This rate was higher than that obtained through other reported processes, such as the complex leaching and electrolysis process with addition of H 2 SO 4 and MnO 2 25 , the extraction processwithtri-n-butyl phosphate(TBP)and tricaprylmethylammonium nitrate ([A336][NO 3 ]) 26 , the mechano-chemical treatment with HCl and (COOH) 2 27 and selective leaching with nitric acid 2 , sulfuric acid 28 and ascorbic acid 29 (Table 1).…”

Section: Resultsmentioning

confidence: 74%

A novel application of hematite precipitation for high effective separation of Fe from Nd-Fe-B scrap

Lin

Chen

et al. 2019

Sci Rep

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Rare earths, e.g. neodymium (Nd), praseodymium (Pr) and dysprosium (Dy), are abundant in the rare earth sintered magnet scrap (Nd-Fe-B scrap), but their recycling is tedious and costly due to the high content of impurity Fe. Herein, a novel approach was developed to effectively recycle rare earths from the scrap via an integrated acid dissolution and hematite precipitation method. The scrap contained 63.4% Fe, 21.6% Nd, 8.1% Pr and 3.9% Dy. It was dissolved in nitric, hydrochloric and sulfuric acids, separately. Nearly all impurity Fe in the scrap was converted to Fe3+ in nitric acid but was converted to Fe2+ in hydrochloric and sulfuric acids. After hydrothermal treatment, the rare earths in the three acids were almost unchanged. From nitric acid, 77.6% of total Fe was removed, but total Fe was not from the hydrochloric and sulfuric acids. By adding glucose, the removal of total Fe was further increased to 99.7% in nitric acid, and 97% of rare earths remained. The major mechanism underlying total Fe removal in nitric acid was the hydrolysis of Fe3+ into hematite, which was promoted by the consumption of nitrate during glucose oxidation. This method effectively recycled rare metals from the waste Nd-Fe-B scrap and showed great potential for industrial application.

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“…Magnet parts first were heated in an electric furnace up to 300 ºC with different dwelling times and temperatures with the purpose to demagnetize and separate the frame [8,9]. In the study, we also evaluated the effect of different calcination temperature levels to the effective of demagnetizing process and magnetic flux density of the NdFeB magnet was measured (equipment Hirst -GM05) before and after the heat treatment for each temperature level and gap of time.…”

Section: Experiments and Methodsmentioning

confidence: 99%

RECOVERING RARE EARTH OXIDE FROM NdFeB MAGNET OF WASTE HDDs BY LEACHING AND SELECTIVE PRECIPITATION METHODS

Huy¹

2018

JST

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Rare earth metal elements have been used widely in many different fields such as in fluorescence, polishing powder, nuclear, laser applications, fiber optics, superconductors, permanent magnets, capacitors and radar technology, etc. In recent years, the development and demand trend led to a large amount of electric and electronic waste (e-waste) generated annually. Faced with issues of shortage on using demand of rare earth metal, many studies have been done in order to recover, recycle and reuse this metal from e-waste. In this research, rare earth elements were recovered from permanent magnet which was dismantled from some kinds of waste hard disk drives HDDs.Result of reseach showed that magnetic flux density of the NdFeB magnet was eliminated completely at 300 ºC in one hour. The leaching efficiency of magnet powder sample reached 99.4 % after 10 min reaction in H 2 SO 4 acid have concentration > 0.3 M under the leaching conditions: stirring speed of 200 rpm, particle size < 0.25 mm, solid/liquid (S/L) ratio 20 g/1l and temperature reaction is 25 ºC. Total rare earth metal elements can be recovered by the using selective crystallization and precipitation method in leaching solution by Na 2 SO 4 and oxalic acid up to 98.36 % was with purity up to 94.32 %. Nd 2 (C 2 O 4 ) transformed into Nd 2 O 3 after being calcinated at 700 C.

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Technique for recovering rare-earth metals from spent sintered Nd-Fe-B magnets without external heating

Cited by 19 publications

References 15 publications

Separation of rare earths and other valuable metals from deep-eutectic solvents: a new alternative for the recycling of used NdFeB magnets

Separation of rare earths and other valuable metals from deep-eutectic solvents: a new alternative for the recycling of used NdFeB magnets

A novel application of hematite precipitation for high effective separation of Fe from Nd-Fe-B scrap

RECOVERING RARE EARTH OXIDE FROM NdFeB MAGNET OF WASTE HDDs BY LEACHING AND SELECTIVE PRECIPITATION METHODS

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