Reclaiming rare earth elements from end-of-life products: A review of the perspectives for urban mining using hydrometallurgical unit operations

Tunsu, Cristian; Petraniková, Martina; Gergorić, Marino; Ekberg, Christian; Retegan, Teodora

doi:10.1016/j.hydromet.2015.06.007

Cited by 266 publications

(175 citation statements)

References 74 publications

(97 reference statements)

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“…The sum is lower than 100% (around 95-97%) which is either due to a combination of experimental errors and our inability to measure elements such as O and N, which also make up a certain percentage of the composition of the NdFeB magnet. The results were in accordance with the literature values of the percentage of elements present in the neodymium magnet [13].…”

Section: Determination Of the Composition Of The Magnet Materialssupporting

confidence: 91%

Characterization and Leaching of Neodymium Magnet Waste and Solvent Extraction of the Rare-Earth Elements Using TODGA

Gergorić

Ekberg

Foreman

et al. 2017

J. Sustain. Metall.

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The rare-earth elements (REEs) are considered as some of the most critical elements in the EU and the USA today. E-scrap, such as end-of-life neodymium magnets, could be a viable secondary source for the recovery of these elements. Neodymium magnets (NdFeB) consist of considerable amounts of Nd, Dy, Pr, and some other REEs, depending on the specific application. Apart from REEs, neodymium magnets are made up of around 60% iron, which can pose a challenge in their recycling. For example, iron can be dissolved along with other elements during leaching or co-extracted during solvent extraction. In this work, extraction of REEs with TODGA (tetraoctyl-diglycolamide) from a real leachate, obtained by neodymium magnet powder dissolution in nitric acid, was studied. The goal was to selectively extract the REEs from other elements in the solution. TODGA was used as the extracting agent due to its selective extraction properties for REEs and other f-block elements. The influence of the diluent on the overall extraction and the selectivity of the extraction was studied in order to determine application feasibility of future processes. To this end, experiments using Solvent 70 (hydrocarbons C11-C14, B0.5 wt% aromatics), hexane, toluene, cyclohexanone and 1-octanol as the diluents were performed. TODGA has shown good selectivity between REEs and other elements in solution under almost all conditions, reaching the highest distribution ratios of REEs in the aliphatic diluents, while the distribution ratios of other non-REEs reach a mere value of 0.1. An exception was cyclohexanone, which has the ability to extract small amounts of ions itself. The highest separation factors between Dy and the light REEs (Nd and Pr) were observed with a 0.01 M solution of TODGA in Solvent 70. REEs, as group, were extracted with 0.1 M solutions of TODGA in all diluents except for cyclohexanone, which led to extraction of Al and B at amounts greater than 10%. Stripping with over 98% efficiency was achieved using MQ water in one step.

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Section: Determination Of the Composition Of The Magnet Materialssupporting

confidence: 91%

Characterization and Leaching of Neodymium Magnet Waste and Solvent Extraction of the Rare-Earth Elements Using TODGA

Gergorić

Ekberg

Foreman

et al. 2017

J. Sustain. Metall.

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“…Due to the uncertainty in the supply of virgin REEs, the possibilities of recovering and reusing them from spent products are presently being investigated [2,[4][5][6]. Some products are rich in materials containing significant amounts of REEs.…”

Section: Introductionmentioning

confidence: 99%

“…Recycling of discarded magnets requires removal of the magnet from the device where it has been in use, demagnetization, size reduction, and a hydrometallurgical (leaching and separation from the liquid phase) or pyrometallurgical (high-temperature processes and separation in molten salts) separation of the constituent elements [2,6,10].…”

Section: Introductionmentioning

confidence: 99%

“…This approach includes leaching of these elements with mineral acids followed by solvent extraction for isolation and separation of the metals of interest [6].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, in many studies [23], it was shown that a typical separation factor between adjacent REEs using the D2EHPA extractant is in the region of 2.5. The separations of neodymium and dysprosium ions in solution have been achieved with organophosphorous extractants, such as PC-88A by Tanaka and co-workers [6]. A separation factor of 525 was obtained at pH 1.1.…”

Section: Introductionmentioning

confidence: 99%

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Separation of Heavy Rare-Earth Elements from Light Rare-Earth Elements Via Solvent Extraction from a Neodymium Magnet Leachate and the Effects of Diluents

Gergorić

Ekberg

Steenari

et al. 2017

J. Sustain. Metall.

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In recent decades, rare-earth elements (REEs) have seen a considerable increase in usage in modern technologies and the so-called green energy sources. The REEs are currently regarded to be among the most critical elements by the European Union (EU) and the United States (USA). Large investments are made in the research of recycling of the REEs from end-of-life products and E-scrap. One potential source for recycling of larger amounts of neodymium and dysprosium are end-of-life neodymium magnets. In this work, the selective extraction of REEs from a sulfuric media leachate (containing Nd, Dy, Pr, Gd, Co, and B) obtained by selective roasting of NdFeB waste and leaching was investigated. The extracting agent D2EHPA (di-(2-ethylhexyl) phosphoric acid) diluted in Solvent 70, hexane, octane, cyclohexanone, chloroform, 1-octanol, and toluene was used for the investigation of the effects of using different diluents on the extraction of REEs and the separation between the light and the heavy REEs. The concentrations of D2EHPA in the used diluents were 0.3, 0.6, 0.9, and 1.2 M. The highest separation factors between the heavy and the light REEs were achieved using 0.3 M D2EHPA in hexane, while no B or Co extraction was measurable. The REEs were completely extracted as a group using 0.9 M or 1.2 M D2EHPA in either octane or hexane, also with no B or Co extraction. The aliphatic nonpolar diluents showed better properties than the aromatic and polar ones. The complete stripping of REEs from the loaded organic phases was proven to be efficient using hydrochloric acid at concentrations of 2 M or higher.

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Hydrometallurgical Recovery of Rare Earth Metals From Spent Fcc Catalysts

Wenzel¹,

Schnaars²,

Kelly³

et al. 2016

Rare Metal Technology 2016

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Reclaiming rare earth elements from end-of-life products: A review of the perspectives for urban mining using hydrometallurgical unit operations

Cited by 266 publications

References 74 publications

Characterization and Leaching of Neodymium Magnet Waste and Solvent Extraction of the Rare-Earth Elements Using TODGA

Characterization and Leaching of Neodymium Magnet Waste and Solvent Extraction of the Rare-Earth Elements Using TODGA

Separation of Heavy Rare-Earth Elements from Light Rare-Earth Elements Via Solvent Extraction from a Neodymium Magnet Leachate and the Effects of Diluents

Hydrometallurgical Recovery of Rare Earth Metals From Spent Fcc Catalysts

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