Recovery of rare earth elements from permanent magnet scraps by pyrometallurgical process

Bian, Yuyang; Guo, Shuqiang; Xu, Yu-ling; Tang, Kai; Lu, Xionggang; Ding, Wei

doi:10.1007/s12598-015-0554-x

Cited by 35 publications

(20 citation statements)

References 19 publications

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“…As previously mentioned, thermal isolation is another pyrometallurgical approach used to recover Nd (in the oxide form) from both spent magnets and Ni-MH batteries. This is a two-step process where the waste material is first oxidized at 1000 • C for 60 min followed by a selective reduction reaction at temperatures between 1400-1550 • C [41][42][43]. For Nd-Fe-B magnets, carbon based reducing agents such as graphite and waste tyre rubber-derived carbon (WTR-DC) materials have been investigated [41,42].…”

Section: Recovery Of Nd Via Pyrometallurgymentioning

confidence: 99%

“…This is a two-step process where the waste material is first oxidized at 1000 • C for 60 min followed by a selective reduction reaction at temperatures between 1400-1550 • C [41][42][43]. For Nd-Fe-B magnets, carbon based reducing agents such as graphite and waste tyre rubber-derived carbon (WTR-DC) materials have been investigated [41,42]. Although similar Nd recovery efficiencies have been reported with both reducing agents (66.4 vs. 64.2%, respectively), the WTR-DC based reduction process had the advantage of generating less solid carbon residue compared to graphite.…”

Section: Recovery Of Nd Via Pyrometallurgymentioning

confidence: 99%

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Analysis of Sustainable Methods to Recover Neodymium

Periyapperuma

Sanchez-Cupido

Pringle

et al. 2021

Sustainable Chemistry

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Neodymium (Nd) is one of the most essential rare-earth metals due to its outstanding properties and crucial role in green energy technologies such as wind turbines and electric vehicles. Some of the key uses includes permanent magnets present in technological applications such as mobile phones and hard disk drives, and in nickel metal hydride batteries. Nd demand is continually growing, but reserves are severely limited, which has put its continued availability at risk. Nd recovery from end-of-life products is one of the most interesting ways to tackle the availability challenge. This perspective concentrates on the different methods to recover Nd from permanent magnets and rechargeable batteries, covering the most developed processes, hydrometallurgy and pyrometallurgy, and with a special focus on electrodeposition using highly electrochemical stable media (e.g., ionic liquids). Among all the ionic liquid chemistries, only phosphonium ionic liquids have been studied in-depth, exploring the impact of temperature, electrodeposition potential, salt concentration, additives (e.g., water) and solvation on the electrodeposition quality and quantity. Finally, the importance of investigating new ionic liquid chemistries, as well as the effect of other metal impurities in the ionic liquid on the deposit composition or the stability of the ionic liquids are discussed. This points to important directions for future work in the field to achieve the important goal of efficient and selective Nd recovery to overcome the increasingly critical supply problems.

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Section: Recovery Of Nd Via Pyrometallurgymentioning

confidence: 99%

Section: Recovery Of Nd Via Pyrometallurgymentioning

confidence: 99%

Analysis of Sustainable Methods to Recover Neodymium

Periyapperuma

Sanchez-Cupido

Pringle

et al. 2021

Sustainable Chemistry

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“…To avoid the formation of NdFeO 3 , Maroufi et al [20] and Bian et al [21] carried out a combined process of oxidation at 1000 °C and consequent reduction above 1400 °C of Nd-Fe-B permanent magnets. In both studies, the product was a mixed rare-earth oxide phase separated from a metal phase mainly containing transition metals (iron, cobalt, and nickel).…”

Section: Introductionmentioning

confidence: 99%

“…In both studies, the product was a mixed rare-earth oxide phase separated from a metal phase mainly containing transition metals (iron, cobalt, and nickel). Maroufi et al used waste tire rubber-derived carbon as the reducing agent, in an attempt to make optimal use of this waste source [20], whereas Bian et al employed conventional carbon reduction [21]. In these two studies, no details are disclosed about the method by which the REOs and the metal phases were separated.…”

Section: Introductionmentioning

confidence: 99%

Selective Roasting of Nd–Fe‒B Permanent Magnets as a Pretreatment Step for Intensified Leaching with an Ionic Liquid

Orefice

Bulck

Blanpain

et al. 2019

J. Sustain. Metall.

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Oxidative roasting of Nd-Fe-B permanent magnets prior to leaching improves the selectivity in the recovery of rare-earth elements over iron. However, the dissolution rate of oxidatively roasted Nd-Fe-B permanent magnets in acidic solutions is very slow, often longer than 24 h. Upon roasting in air at temperatures above 500 °C, the neodymium metal is not converted to Nd 2 O 3 , but rather to the ternary NdFeO 3 phase. NdFeO 3 is much more difficult to dissolve than Nd 2 O 3. In this work, the formation of NdFeO 3 was avoided by roasting Nd-Fe-B permanent magnet production scrap in argon atmosphere, having an oxygen content of p O 2 ≤ 10 −20 atm, with the addition of 5 wt% of carbon as an iron reducing agent. For all the non-oxidizing iron roasting conditions investigated, the iron in the Nd-Fe-B scrap formed a cobalt-containing metallic phase, clearly distinct from the rare-earth phase at microscopic level. The thermal treatment was optimized to obtain a clear phase separation of metallic iron and rare-earth phase also at the macroscopic level, to enable easy mechanical removal of iron prior to the leaching step. The sample roasted at the optimum conditions (i.e., 5 wt% carbon, no flux, no quenching step, roasting temperature of 1400 °C and roasting time of 2 h) was leached in the water-containing ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf 2 N]. A leaching time of only 20 min was sufficient to completely dissolve the rare-earth elements. The rare-earth elements/iron ratio in the leachate was about 50 times higher than the initial rare-earth elements/iron ratio in the Nd-Fe-B scrap. Therefore, roasting in argon with addition of a small amount of carbon is an efficient process step to avoid the formation of NdFeO 3 and to separate the rare-earth elements from the iron, resulting in selective leaching for the recovery of rare-earth elements from Nd-Fe-B permanent magnets.

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“…The slag consisted of 50–60 wt.% RE. Bian et al used pyrometallurgical process to recover rare earth elements from Nd–Fe–B permanent magnet. The magnet scraps were first pulverized to fine particles.…”

Section: Introductionmentioning

confidence: 99%

Phase relations of CaO‐Al₂O₃‐Sc₂O₃ ternary system

et al. 2018

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We investigated the isothermal section of the CaO-Al 2 O 3 -Sc 2 O 3 ternary system at 1773 and 1873 K for 24 hours in Ar, and quenched in water to determine the operative phase equilibrate. The composition of the phases in equilibrium was determined by electron probe microanalysis. The isothermal section phase diagram of two temperature points (1773 and 1873 K) is obtained. The 1773 K isothermal section consists of one liquid compound (L), six binary compounds (CaO+L, ) to exist at the isothermal section. The experimental information obtained in the present work not only is essential for the thermodynamic assessment of the CaO-Al 2 O 3 -Sc 2 O 3 ternary system, but also is important for further investigation on separation of rare earths from metallurgical slags and rare-earth recovery.

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Recovery of rare earth elements from permanent magnet scraps by pyrometallurgical process

Cited by 35 publications

References 19 publications

Analysis of Sustainable Methods to Recover Neodymium

Analysis of Sustainable Methods to Recover Neodymium

Selective Roasting of Nd–Fe‒B Permanent Magnets as a Pretreatment Step for Intensified Leaching with an Ionic Liquid

Phase relations of CaO‐Al₂O₃‐Sc₂O₃ ternary system

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Recovery of rare earth elements from permanent magnet scraps by pyrometallurgical process

Cited by 35 publications

References 19 publications

Analysis of Sustainable Methods to Recover Neodymium

Analysis of Sustainable Methods to Recover Neodymium

Selective Roasting of Nd–Fe‒B Permanent Magnets as a Pretreatment Step for Intensified Leaching with an Ionic Liquid

Phase relations of CaO‐Al2O3‐Sc2O3 ternary system

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Phase relations of CaO‐Al₂O₃‐Sc₂O₃ ternary system