Recycling of rare earths: a critical review

Binnemans, Koen; Jones, Peter Tom; Blanpain, Bart; Gerven, Tom Van; Yang, Yongxiang; Walton, Allan; Buchert, Matthias

doi:10.1016/j.jclepro.2012.12.037

Cited by 1,916 publications

(1,333 citation statements)

References 115 publications

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“…They are also used in processes such as petroleum refining. Over the past couple of decades, around 95% of the world's demand for REEs was provided by China, which led to increased prices and supply risk after the global financial crisis of 2011 [1]. They are, up to this day, classified as the elements with the highest supply risk within the EU [2], with the heavy REE elements being at highest supply risk.…”

Section: Introductionmentioning

confidence: 99%

“…Recycling can help reduce fluctuations of prices by reducing the potential for monopolies, even if recycling cannot totally replace the supply of REEs from mines. Less than 1% of the REEs were recycled by 2011 [1], and no data have been provided on the development of new large-scale processes. The scarcity of data on the quantity of REE materials from magnets in the waste streams and the fate of the magnets after shredding has handicapped the development of REE recycling processes [5].…”

Section: Introductionmentioning

confidence: 99%

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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: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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.

View full text Add to dashboard Cite

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“…The market of the Nd-Fe-B magnets is about 60,000 ton per year and is expected to grow [7]. It is estimated that HDDs are the single largest products of NdFeB magnets in electronic goods with almost 600 million manufactured annually supplying 6000 to 12,000 tons of neodymium-iron-boron alloy [8]. Taking all of these into account, a full characteristic of scrap Nd-Fe-B magnets was carried out in hopes that this will help for further reprocessing of these materials.…”

Section: Introductionmentioning

confidence: 99%

Complex Characteristics of Sintered Nd-Fe-B Magnets in Terms of Hydrogen Based Recycling

et al. 2017

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Sintered Nd-Fe-B magnets, dismantled by the P.P.H.U. Polblume company from scrap hard disc drives and medical device, were thermally demagnetized and analyzed in terms of their chemical composition, structure and magnetic properties. Magnets from hard disc drives drives had a magnetic structure of two opposite poles in a plane of a magnet and were covered with a nickel coating (around 50 µm in thick), which however was often discontinuous and deeply scratched. The majority of the magnets were partially destroyed (broken or corroded). The magnet from hard disc drives were basically made of iron (65±1 wt%) and neodymium (30±2 wt%) however, they also included alloying elements such as Co (1-2.5 wt%), Dy (0-1 wt%) or Pr (0-5 wt%). The magnets from medical device consisted only of iron (65±1 wt%) and neodymium (34±1 wt%). Magnets of both kinds were textured thus their XRD patterns were amended. Diffraction patterns, typical for the Nd2Fe14B (ϕ) phase, were achieved after mechanical crushing of the bulk magnets. A regular X-ray diffraction pattern was achieved after mechanical crushing of the magnets. The microstructure of both types of the magnets, observed by scanning electron microscopy, consisted of grey grains of a Nd2Fe14B (ϕ) phase and a Nd-rich grain boundary phase. The magnets from hard disc drives exhibited excellent magnetic properties and anisotropy: maximum energy product above 300 kJ/m 3 , remanence around 1.4 T and coercivity around 1000 kA/m, slightly varying between each magnet. Magnetic properties of medical magnet were only a little worse: maximum energy product above 200 kJ/m 3 , remanence around 1.1 T and coercivity around 900 kA/m. Hydrogen disproportionation phase diagrams (temperature vs. pressure) were constructed for both kinds of the magnets, revealing possible conditions for the hydrogenation, disproportionation, desorption and recombination reaction.

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“…Hydrometallurgical processes are commonly used to separate rareearth elements from a glass host. However, these processes consume large amounts of chemicals and release harmful residues, for example, recovery of rare-earth elements from spent optical glass by leaching using NaOH followed by HCl [11]. Ce recovery from spent glass-polishing powder has been achieved using H 2 C 2 O 4 and H 2 SO 4 [6], NaOH [7], and HNO 3 /H 2 O 2 mixture [8] to dissolve the powder.…”

Section: Introductionmentioning

confidence: 99%

Rare-Earth Recovery from Soda Lime Silicate Glass Cullet by P2O5 Addition

Hakim

Saitoh

Takebe

2016

J. Sustain. Metall.

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Many rare-earth elements are incorporated into fine glass particles found in glass-polishing sludge and wasted without further exploitation. This study attempts to recover rare-earth element from simulated glass particles. For this purpose, a series of P 2 O 5 concentrations were added to glass cullet doped with Eu 2 O 3 , followed by melting and cooling to room temperature. Recovery of rare-earth element was conducted by leaching into water. Europium was selected as dopant into the opaque samples, and its sensitive fluorescence spectrum utilized to estimate changes in the neighborhood of Eu 3? ions upon P 2 O 5 addition. On the basis of fluorescence and infrared (IR) spectral analysis, it is estimated that significant amounts of Eu 3? ions began to coordinate with PO 4 tetrahedral units when the concentration of P 2 O 5 (P) was higher than the concentration of alkali and alkaline-earth metal oxides (A), expressed as A/P-ratio \1. In this condition, the recovery efficiency of europium element by leaching into water increased to 50-100 % relative to its initial concentration. IR spectra suggested that the increased leaching was promoted by the solubility of metaphosphate chains. This study suggests a process for recovery of rare-earth elements from glass particles found in glass-polishing sludge without use of acid treatment.

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Recycling of rare earths: a critical review

Cited by 1,916 publications

References 115 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

Complex Characteristics of Sintered Nd-Fe-B Magnets in Terms of Hydrogen Based Recycling

Rare-Earth Recovery from Soda Lime Silicate Glass Cullet by P2O5 Addition

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