Electrochemical routes for environmentally friendly recycling of rare-earth-based (Sm–Co) permanent magnets

The consumption of critical raw materials, especially those in permanent magnets of Nd–Fe–B and Sm–Co-type, has significantly grown in the past decade. With predictions on further electrification growing exponentially the demand for these materials will even increase. This implies that efforts in as...

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Bibliographic Details
Published in:Journal of applied electrochemistry 2022-07, Vol.52 (7), p.1081-1090
Main Authors: Xu, Xuan, Khoshsima, Sina, Karajic, Milana, Balderman, Jan, Markovic, Katarina, Scancar, Janez, Samardzija, Zoran, Sturm, Saso, Rozman, Kristina Zuzek
Format: Article
Language:English
Subjects:
Anodizing
Cathodes
Chemistry
Chemistry and Materials Science
Cobalt
Copper
Direct current
Electrification
Electrochemical Processes
Electrochemistry
Electrodeposition
Energy consumption
Industrial Chemistry/Chemical Engineering
Iron
Leaching
Materials recovery
Neodymium
Oxidation
Permanent magnets
Physical Chemistry
Rare earth elements
Raw materials
Recycling
Research Article
Selectivity
Strategic materials
Zirconium
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Summary:The consumption of critical raw materials, especially those in permanent magnets of Nd–Fe–B and Sm–Co-type, has significantly grown in the past decade. With predictions on further electrification growing exponentially the demand for these materials will even increase. This implies that efforts in assuring sustainability must involve recycling from secondary resources. In recent years the electrochemical approaches in recycling have been extensively investigated and applied owing to their advantages of high efficiency and selectivity, easy operation, low energy consumption, and environmental friendliness. In this paper, we investigate the Sm 2 (Co,Fe,Cu,Zr) 17 permanent magnet leaching process using the anodic oxidation to be paired with the metal deposition on the cathode. Linear sweep voltammetry was performed from − 0.15 to 1 V versus Pt quasi reference electrode that indicated current peaks that would correspond to some preferential leaching of the crystal phases contained in the magnet. The latter was confirmed using the SEM/EDXS analysis. The continuous leaching of the Sm 2 (Co,Fe,Cu,Zr) 17 magnet was performed at a direct current density of 2, 4 and 8 mA cm −2 at the time period of 0–240, 240–480 and 480–720 min, respectively. The ICP-MS results confirmed the leaching of all the metals from the original Sm 2 (Co,Fe,Cu,Zr) 17 permanent magnet. The concentration of Sm 3+ , Cu 2+ , Fe 2+ and Zr 2+ increases linearly along with the leaching time. Reversely the concentration of Co 2+ decreases linearly due to its consumption by electrodeposition of Co, Fe and Cu on the cathode. The presented paired electrochemical process could serve as a starting point for the recycling and recovery of critical raw materials without any acid usage and waste generation. Graphical abstract
ISSN:0021-891X
1572-8838
DOI:10.1007/s10800-022-01696-9