Recycling of NdFeB magnets using nitration, calcination and water leaching for REE recovery

Önal, Mehmet Ali Recai; Aktan, Emir; Gerven, Tom Van; Blanpain, Bart; Gerven, Tom Van; Guo, Muxing

doi:10.1016/j.hydromet.2016.11.006

Cited by 70 publications

(26 citation statements)

References 26 publications

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“…Optimum conditions for this process were S:L (solid-to-liquid ratio) ratio of 20 g/L, leaching time of 15 min, and concentrations of 3 mol/L HCl and 1.5 mol/L H 2 SO 4 . The vast majority of research so far has been conducted using strong mineral acids for leaching [12][13][14][15]. The extraction of the metals of interest after leaching is most commonly done using solvent extraction agents like di-(2-ethylhexyl) phosphoric acid (D2EHPA), tributyl phosphate (TBP) and 2-ethylhexyl phosphonic acid (HEHEHP) [16], although a lot of research in recent years has been focused on the investigation of solvent extraction using ionic liquids as promising new, environmentally friendly extractants [3,17].…”

Section: Introductionmentioning

confidence: 99%

Leaching and Recovery of Rare-Earth Elements from Neodymium Magnet Waste Using Organic Acids

Gergorić

Ravaux²,

Steenari

et al. 2018

Metals

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Over the last decade, rare-earth elements (REEs) have become critical in the European Union (EU) in terms of supply risk, and they remain critical to this day. End-of-life electronic scrap (e-scrap) recycling can provide a partial solution to the supply of REEs in the EU. One such product is end-of-life neodymium (NdFeB) magnets, which can be a feasible source of Nd, Dy, and Pr. REEs are normally leached out of NdFeB magnet waste using strong mineral acids, which can have an adverse impact on the environment in case of accidental release. Organic acids can be a solution to this problem due to easier handling, degradability, and less poisonous gas evolution during leaching. However, the literature on leaching NdFeB magnets waste with organic acids is very scarce and poorly investigated. This paper investigates the recovery of Nd, Pr, and Dy from NdFeB magnets waste powder using leaching and solvent extraction. The goal was to determine potential selectivity between the recovery of REEs and other impurities in the material. Citric acid and acetic acid were used as leaching agents, while di-(2-ethylhexyl) phosphoric acid (D2EHPA) was used for preliminary solvent extraction tests. The highest leaching efficiencies were achieved with 1 mol/L citric acid (where almost 100% of the REEs were leached after 24 h) and 1 mol/L acetic acid (where >95% of the REEs were leached). Fe and Co—two major impurities—were co-leached into the solution, and no leaching selectivity was achieved between the impurities and the REEs. The solvent extraction experiments with D2EHPA in Solvent 70 on 1 mol/L leachates of both acetic acid and citric acid showed much higher affinity for Nd than Fe, with better extraction properties observed in acetic acid leachate. The results showed that acetic acid and citric acid are feasible for the recovery of REEs out of NdFeB waste under certain conditions.

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Section: Introductionmentioning

confidence: 99%

Leaching and Recovery of Rare-Earth Elements from Neodymium Magnet Waste Using Organic Acids

Gergorić

Ravaux²,

Steenari

et al. 2018

Metals

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“…In most cases, hydrochloric acid [18] and nitric acid [19] have been used as the leaching agent from scrap magnets. In this work, we first investigated the effect of the hydrochloric acid concentration on the extractability of metal ions, including Nd (III), Dy (III), and Ni (II), the results of which are shown in Figure 1.…”

Section: Extraction Of Metal Ions From Aqueous Acid Solutionsmentioning

confidence: 99%

Extraction of Rare Earth Metal Ions with an Undiluted Hydrophobic Pseudoprotic Ionic Liquid

Matsumoto

Yamaguchi

Tahara

2020

Metals

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Recovering and concentrating rare earth metals (Nd and Dy) from waste permanent magnets rather than discarding them into the environment without pretreatment is critical for metal recycling and environmental responsibility. In this work, we used an undiluted hydrophobic pseudoprotic ionic liquid composed of trioctylamine and decanoic acid as an extractant to separate rare earth metals from aqueous media with a solvent extraction technique. This ionic liquid proved to be excellent with low viscosity and extractability reaching 100% for Nd and Dy in the presence of salts like sodium chloride and sodium nitrate. In acidic media, extractability decreased with increasing acid concentrations. Under all our experimental conditions, the rare earth metals (Nd and Dy) were found to be preferentially extracted compared to nickel with the distribution ratios of Dy higher than those of Nd.

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“…1,2,14 In general, these routes include pyrometallurgical, 15,16 hydrometallurgical [17][18][19][20] and solvometallurgical 21 approaches, or a combination of them. [22][23][24] In contrast, very limited attention has been given to the recycling of bonded NdFeB magnets. This lack of attention can be explained by the much lower rare-earth content of the bonded magnets compared to that of sintered magnets, as well as by the fact that the presence of the polymeric binders or resins makes direct recycling routes (such as hydrogen decrepitation) difficult.…”

Section: Introductionmentioning

confidence: 99%

Recycling of bonded NdFeB permanent magnets using ionic liquids

et al. 2020

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Recycling of NdFeB magnets using nitration, calcination and water leaching for REE recovery

Cited by 70 publications

References 26 publications

Leaching and Recovery of Rare-Earth Elements from Neodymium Magnet Waste Using Organic Acids

Leaching and Recovery of Rare-Earth Elements from Neodymium Magnet Waste Using Organic Acids

Extraction of Rare Earth Metal Ions with an Undiluted Hydrophobic Pseudoprotic Ionic Liquid

Recycling of bonded NdFeB permanent magnets using ionic liquids

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