Oxidative Roasting–Selective Pressure Leaching Process for Rare Earth Recovery from NdFeB Magnet Scrap

Jiang, Yinju; Deng, Yongchun; Xin, Wenbin; Guo, Chao

doi:10.1007/s12666-020-01888-x

Cited by 19 publications

(6 citation statements)

References 13 publications

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“…The selective pressure HCl acid leaching process for NdFeB magnets was evaluated in detail. 24 Yoon et al proposed a leaching mechanism for NdFeB magnets, and the activation energy was calculated. Nd and Nd 2 O 3 in the NdFeB magnet was converted to Nd 2 (SO 4 ) 3 in solution with 3 mol L −1 H 2 SO 4 and a pulp density of 110.8 g L −1 for 4 h. It was reported that the leaching kinetics followed a shrinking core model.…”

Section: Introductionmentioning

confidence: 99%

Recycling of NdFeB magnets employing oxidation, selective leaching, and iron precipitation in an autoclave

et al. 2023

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Section: Introductionmentioning

confidence: 99%

Recycling of NdFeB magnets employing oxidation, selective leaching, and iron precipitation in an autoclave

et al. 2023

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“…-Concentration of REEs and other elements in the leach solution (ppm): Y (13), La (19), Ce (62), Nd (17), Dy (3), Sc (15), Na (3859), Al (4638), Ca (441), Ti (82), Fe (450).…”

Section: Samplesmentioning

confidence: 99%

“…(1) The samples were crushed, milled and roasted above 100 -Leaching rate of rare earth was 96.27% along with 13.33% Fe [19] Another resource for REEs recovery is end-of-life products such as NdFeB magnets. Depending on the application, REEs can make up about 31-32% by weight of NdFeB magnets; these REEs are mainly Nd and Pr, along with small amounts of Dy, Tb, and Gd [15].…”

Section: Samplesmentioning

confidence: 99%

“…Red mud contains a large number of valuable metals including rare earth elements, making it a potential and important resource for these metals in recent times [6]. Table 1 lists some investigated processes for the recovery of REEs from red mud and end-of-life NdFeB magnets [7][8][9][10][11][12][13][14][15][16][17][18][19]. In most processes, inorganic acid solutions such as HCl, HNO 3 , and H 2 SO 4 as leaching agents are employed to effectively dissolve iron oxides from red mud [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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Selective Dissolution of Nd2O3 from the Mixture with Fe2O3 and Ga2O3 by Using Inorganic Acid Solutions Containing Ethylene Glycol

Nguyen

Kim

Lee

2022

Metals

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Rare earth elements (REEs) are strategically critical in the manufacture of advanced materials. Red mud and end-of-life NdFeB magnets can be good secondary sources for REEs, but recovery is difficult due to the high iron oxide content and small amount of REEs. Oxide mixtures whose composition of Fe, Nd, and Ga was similar to that in red mud were employed in experiments. In this study, a relatively inexpensive non-aqueous system was used to selectively dissolve Nd2O3 in a mixture with Fe2O3 and Ga2O3. The addition of ethylene glycol (EG) to HCl and H2SO4 solution depressed the dissolution of Fe2O3 and Ga2O3 from the mixtures, and thus selective dissolution of Nd2O3 was possible. The optimum conditions were as follows: (a) 1.0 M HCl in EG, 25 °C ± 1 °C, 50 g/L pulp density, 120 min, 200 rpm; and (b) 0.05 M H2SO4 in EG, 25 °C ± 1 °C, 50 g/L pulp density, 60 min, 300 rpm. Under these conditions, Nd2O3 was completely dissolved, whereas no Fe2O3 or Ga2O3 was dissolved by the H2SO4 system, and the dissolution percentage of these two oxides by the HCl system was less than 1%. Due to the selective dissolution of Nd2O3 from the oxide mixtures, it is simple to recover Nd. An efficient process can be developed for the recovery of REEs from red mud and end-of-life NdFeB magnets by applying our results.

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“…Considering the instable supply chain of REEs, such as Nd and Dy, which are core constituents of NdFeB magnets, recovering REEs from end-of-life magnets is an essential way to decrease the supply risk . Various metallurgical processes were carried out to separate and recover the REEs from the spent NdFeB magnets, including hydrometallurgy, − pyrometallurgy, − chlorinated metallurgy, , electrochemistry, − solvometallurgy, liquid metal extraction, and membrane separation. , …”

Section: Introductionmentioning

confidence: 99%

ZnCl₂: A Green Brønsted Acid for Selectively Recovering Rare Earth Elements from Spent NdFeB Permanent Magnets

Ding

Liu

Zhang

et al. 2022

Environ. Sci. Technol.

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The spent neodymium–iron–boron (NdFeB) magnet is a highly valuable secondary resource of rare earth elements (REEs). Hydrometallurgical processes are widely used in recovering REEs from spent NdFeB magnets, but they will consume large amounts of organic chemicals, leading to severe environmental pollution. This work developed an alternative green route to selectively recover REEs from spent NdFeB permanent magnets using a purely inorganic zinc salt. The Hammett acidity measurement showed that concentrated ZnCl2 solutions could be regarded as a strong Brønsted acid. Concentrated ZnCl2 solutions achieved a high separation factor (>1 × 105) between neodymium and iron through simple dissolution of their corresponding oxide mixture. In the simulated recovery process of spent NdFeB magnets, the Nd2O3 product was successfully recovered with a purity close to 100% after selective leaching by ZnCl2 solution, sulfate double-salt precipitation, and oxalic acid precipitation. The separation performance of the ZnCl2 solution for Nd2O3 and Fe2O3 remained almost unchanged after four cycles. The energy consumption and chemical inputs of this process are about 1/10 and half of the traditional hydrometallurgy process separately. This work provides a promising approach for the green recovery of secondary REE resources.

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Oxidative Roasting–Selective Pressure Leaching Process for Rare Earth Recovery from NdFeB Magnet Scrap

Cited by 19 publications

References 13 publications

Recycling of NdFeB magnets employing oxidation, selective leaching, and iron precipitation in an autoclave

Recycling of NdFeB magnets employing oxidation, selective leaching, and iron precipitation in an autoclave

Selective Dissolution of Nd2O3 from the Mixture with Fe2O3 and Ga2O3 by Using Inorganic Acid Solutions Containing Ethylene Glycol

ZnCl₂: A Green Brønsted Acid for Selectively Recovering Rare Earth Elements from Spent NdFeB Permanent Magnets

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Oxidative Roasting–Selective Pressure Leaching Process for Rare Earth Recovery from NdFeB Magnet Scrap

Cited by 19 publications

References 13 publications

Recycling of NdFeB magnets employing oxidation, selective leaching, and iron precipitation in an autoclave

Recycling of NdFeB magnets employing oxidation, selective leaching, and iron precipitation in an autoclave

Selective Dissolution of Nd2O3 from the Mixture with Fe2O3 and Ga2O3 by Using Inorganic Acid Solutions Containing Ethylene Glycol

ZnCl2: A Green Brønsted Acid for Selectively Recovering Rare Earth Elements from Spent NdFeB Permanent Magnets

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ZnCl₂: A Green Brønsted Acid for Selectively Recovering Rare Earth Elements from Spent NdFeB Permanent Magnets