Recovery of pure rare earth elements from waste data storage devices as magnet precursors via a hydrometallurgical route combining precipitation and chelating cation exchange techniques
Abstract
This study investigates the recovery of rare earth elements from magnets derived from end-of-life data storage devices. The dismantled magnets were demagnetized and subsequently crushed into a fine powder using a jaw crusher with a 2 mm gap setting. The resulting powder was subjected to hydrochloric acid leaching; however, the obtained chloride-based rare earth solution contained significant iron, nickel, cobalt, and manganese impurities. Based on thermodynamic evaluations, the bulk separation of the main impurities was carried out by oxidative precipitation, while fine purification was performed using an ion exchange process. During precipitation, over 98% of the impurities were successfully removed with a rare earth loss of approximately 3%. Neodymium, praseodymium, and dysprosium were then separated into a pure solution fraction using chelating cation exchange chromatography. The rare earth elements were precipitated via oxalate precipitation, and the precipitate was subsequently calcined at 800 °C to produce a 99.9% pure, didymium-based mixed oxide. Although the presented method yielded highly promising results, the fine-tuning of the separation process and the optimization of the overall yield require further research.
References
K. Habib, K. Parajuly, H. Wenzel, „Tracking the Flow of Resources in Electronic Waste - The Case of End-of-Life Computer Hard Disk Drives,” Environmental Science & Technology, vol. 49, no. 20, p. https://doi.org/10.1021/acs.est.5b02264, 2015.
V. Forti, „The Global E-waste Monitor 2020: Quantities, flows and the circular economy potential,” United Nations University (UNU) / UNITAR, International Telecommunication Union (ITU) & International Solid Waste Association (ISWA), Bonn/Geneva/Rotterdam.
K. Binnemans, P. T. Jones, B. Blanpain et al., „Recycling of rare earths: a critical review,” Journal of Cleaner Production, vol. 51, no. 1, pp. 1-22, 2013.
O. Gutfleisch, M. A. Willhard, E. Brück et al., „Magnetic materials and devices for the 21st century: stronger, lighter, and more energy efficient,” Advanced Materials, vol. 23, no. 7, pp. 821-842, 2011.
G. Várhegyi, Fémkohászattan IV, Budapest: Tankönyvkiadó, 1967.
S. Wickleder, „Physical Chemistry of Lanthanide Compounds,” Chemical Reviews, vol. 102, no. 6, pp. 2011-2008, 2002.
R. Choppin, „The chemical behavior of the lanthanides and the actinides,” Journal of Radioanalytical and Nuclear Chemistry, vol. 273, no. 3, pp. 695-703, 2007.
F. Xie, T. Zhang, D. Dreisinger et al., „A critical review on solvent extraction of rare earths from aqueous solutions,” Minerals Engineering, vol. 56, no. 1, pp. 10-28, 2014.
M. Jha, A. Kumari, A. Panda et al., „Review on hydrometallurgical recovery of rare earth metals (REMs) from primary and secondary resources,” Hydrometallurgy, vol. 165, pp. 2-26, 2016.
F. Habashi, „Extractive metallurgy of rare earths,” Canadian Metallurgical Quarterly, vol. 52, no. 3, pp. 224-233, 2013.
O. Takeda, H. Okabe, Y. Umetsu, „Recovery of Neodymium from Magnet Scrap by Utilizing Magnesium as a Extraction Solvent,” Materials Transactions, vol. 47, no. 3, pp. 888-892, 2006.
I. B. Illés, T. Kékesi, A magnézium és a titán előállítása, Miskolc: Miskolci Egyetemi Kiadó, 2019.
Z. Horváth, G. Pásztor, Vákuum-metallurgia, Budapest: Műszaki Tankönyvkiadó, 1984.
A. Danczak, I. Chojnacka, S. Matuska et al., „The recycling-oriented material characterization of hard disk drives with special emphasis on NdFeB magnets,” Physicochem. Probl. Miner. Process., vol. 54, no. 2, pp. 363-376, 2018.
L. Ng Yong, H. E. Choo, A. Chiang, C. Ng, „Recovery of rare earth elements: A comprehensive review from the perspective of secondary sources and potentially greener leachants,” Separation and Purification Technology, vol. 382, no. 1, p. https://doi.org/10.1016/j.seppur.2025.135752, 2025.
T. Kékesi, T. Török, M. Isshiki, „Anion exchange of chromium, molybdenum and tungsten species of various oxidation states, providing the basis for separation and purification in HCl solutions,” Hydrometallurgy, vol. 77, no. 1, pp. 81-88, 2005.
B. Mason, C. B. Moore, Principles of Geochemistry (4th Edition), Toronto: John Wiley & Sons, 1982.
S. A. Cotton, P. R. Raithby, „Systematics and surprises in lanthanide coordination chemistry,” Coordination Chemistry Reviews, vol. 340, pp. 220-231, 2017.
J. O. Claassen, R. F. Sandenbergh, „Influence of mixing on the quality of iron precipitates,” Hydrometallurgy, vol. 87, no. 1, pp. 112-123, 2007.
Z. Horváth, Fémkohászattan III, Budapest: Tankönyvkiadó, 1987.
B. Yang, G. Chen et al., „Separation of Iron from ZnSO4 solution by oxygen pressure enhanced hydrothermal precipitation,” The Canadian Journal of Metallurgy and Materials Science, vol. 64, no. 1, pp. 286-295, 2025.
T. Erdey-Grúz, Transzportfolyamatok vizes oldatokban, Budapest: Akadémia Kiadó, 1971.
V. Hoogerstraete, A. Blanpain, B. Van den Bossche, K. Binnemans, „Recycling of NdFeB magnets using nitration, calcination and water leaching for REE recovery,” Green Chemistry, vol. 16, no. 7, pp. 3418-3424, 2014.
M. Önal, E. Aktan, C. Blanpain et al., „Recycling of NdFeB magnets using nitration, calcination and water leaching for REE recovery,” Hydrometallurgy, vol. 167, no. 1, pp. 115-123, 2017.
