{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T03:40:59Z","timestamp":1788406859585,"version":"build-2803163510"},"reference-count":33,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2025,6,8]],"date-time":"2025-06-08T00:00:00Z","timestamp":1749340800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Rector\u2019s pro-quality grant, Silesian University of Technology","award":["10\/100\/RGJ25\/0107"],"award-info":[{"award-number":["10\/100\/RGJ25\/0107"]}]},{"name":"Rector\u2019s pro-quality grant, Silesian University of Technology","award":["10\/100\/RGJ25\/0107"],"award-info":[{"award-number":["10\/100\/RGJ25\/0107"]}]},{"name":"Silesian University of Technology","award":["10\/100\/RGJ25\/0107"],"award-info":[{"award-number":["10\/100\/RGJ25\/0107"]}]},{"name":"Silesian University of Technology","award":["10\/100\/RGJ25\/0107"],"award-info":[{"award-number":["10\/100\/RGJ25\/0107"]}]},{"name":"KOMAG Institute of Mining Technology","award":["10\/100\/RGJ25\/0107"],"award-info":[{"award-number":["10\/100\/RGJ25\/0107"]}]},{"name":"KOMAG Institute of Mining Technology","award":["10\/100\/RGJ25\/0107"],"award-info":[{"award-number":["10\/100\/RGJ25\/0107"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Rare earth elements (REEs), particularly neodymium (Nd), dysprosium (Dy), and praseodymium (Pr), are critical in the production of neodymium\u2013iron\u2013boron (NdFeB) magnets used in electronic devices, wind turbines, and electric vehicles. Due to the limited availability of these metals, their recovery from waste electronic equipment such as hard disk drives (HDDs) offers a promising solution. The aim of this study was to develop a method to grind NdFeB magnets obtained from the physical recycling of HDD. The recycled magnets were ground using a planetary mill. A review of the literature highlights the limitations of the currently used grinding methods, which require energy-intensive pretreatment processes, specialised conditions, or expensive equipment. This study employed a Fritsch planetary mill, tungsten carbide grinding balls, and ethanol as a grinding medium. NdFeB magnet samples (120 g) were ground for different durations (0.5 h\u201315 h) at a speed of 300 rpm, using a cyclic operating mode to minimise material heating. The resulting powders were analysed using a laser particle analyser, an optical microscope, and an X-ray diffractometer. The results enable the determination of optimal grinding parameters, achieving an average particle size (d50) below 5 \u03bcm, which is essential for further processing and new magnet production. Finally, the economic and environmental aspects of producing the neodymium alloy were analysed.<\/jats:p>","DOI":"10.3390\/ma18122697","type":"journal-article","created":{"date-parts":[[2025,6,9]],"date-time":"2025-06-09T05:54:05Z","timestamp":1749448445000},"page":"2697","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Sustainable Recovery of Rare Earth Elements from Hard Disks: Grinding NdFeB Magnets and Financial and Environmental Analysis"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1574-6190","authenticated-orcid":false,"given":"Pawe\u0142","family":"Friebe","sequence":"first","affiliation":[{"name":"KOMAG Institute of Mining Technology, 44-100 Gliwice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4251-4275","authenticated-orcid":false,"given":"Tomasz","family":"Suponik","sequence":"additional","affiliation":[{"name":"Department of Geoengineering and Resource Exploitation, Silesian University of Technology, 44-100 Gliwice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2606-0525","authenticated-orcid":false,"given":"Pawe\u0142 M.","family":"Nuckowski","sequence":"additional","affiliation":[{"name":"Materials Research Laboratory, Silesian University of Technology, 44-100 Gliwice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6869-5115","authenticated-orcid":false,"given":"Marek","family":"Kremzer","sequence":"additional","affiliation":[{"name":"Nanotechnology and Materials Technology Scientific and Didactic Laboratory, Silesian University of Technology, 44-100 Gliwice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7141-8960","authenticated-orcid":false,"given":"Rafa\u0142","family":"Baron","sequence":"additional","affiliation":[{"name":"KOMAG Institute of Mining Technology, 44-100 Gliwice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9393-4309","authenticated-orcid":false,"given":"Piotr","family":"Matusiak","sequence":"additional","affiliation":[{"name":"KOMAG Institute of Mining Technology, 44-100 Gliwice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5547-376X","authenticated-orcid":false,"given":"Daniel","family":"Kowol","sequence":"additional","affiliation":[{"name":"KOMAG Institute of Mining Technology, 44-100 Gliwice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Ben\u00edtez-Andrades, J.A., Garc\u00eda-Llamas, P., Taboada, \u00c1., Est\u00e9vez-Mauriz, L., and Baelo, R. (2023). Research on Hard Drives in the Context of the Construction of Shredding Knives in the Recovery of Rare Earth Elements. Global Challenges for a Sustainable Society, Springer. Springer Proceedings in Earth and Environmental Sciences.","DOI":"10.1007\/978-3-031-25840-4"},{"key":"ref_2","unstructured":"Friebe, P. (2023). Przegl\u0105d literatury dotycz\u0105cej odzysku sproszkowanej mieszaniny stopu NdFeB z ZSEiE. KOMEKO Konferencja Naukowo-Techniczna Przemys\u0142 Przyjazny dla \u015arodowiska, KOMAG Institute of Mining Technology."},{"key":"ref_3","first-page":"143","article-title":"Development of a Prototype Shredder for WEEE Equipped with NdFeB Magnets","volume":"41","author":"Friebe","year":"2023","journal-title":"Min. Mach."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1016\/j.spc.2024.03.027","article-title":"Mapping the Flows and Stocks of Permanent Magnets Rare Earth Elements for Powering a Circular Economy in the UK","volume":"47","author":"Hsu","year":"2024","journal-title":"Sustain. Prod. Consum."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"07A721","DOI":"10.1063\/1.3676616","article-title":"Rare Earth Elements and Permanent Magnets (Invited)","volume":"111","author":"Dent","year":"2012","journal-title":"J. Appl. Phys."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"372","DOI":"10.1016\/j.wasman.2017.01.032","article-title":"Neodymium as the Main Feature of Permanent Magnets from Hard Disk Drives (HDDs)","volume":"61","author":"Veit","year":"2017","journal-title":"Waste Manag."},{"key":"ref_7","unstructured":"Collocott, S., Gwan, P., Kalan, B., Lovatt, H., Wu, W., and Watterson, P. (2004). Applications of Rare-Earth Permanent Magnets in Electrical Machines: From Motors for Niche Applications to Hybrid Electric Vehicles, University of Technology."},{"key":"ref_8","first-page":"4056","article-title":"An Overview of Neodymium Magnets over Normal Magnets for the Generation of Energy","volume":"2","author":"Shewane","year":"2014","journal-title":"Int. J. Recent Innov. Trends Comput. Commun."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Heim, J.W., and Vander Wal, R.L. (2023). NdFeB Permanent Magnet Uses, Projected Growth Rates and Nd Plus Dy Demands across End-Use Sectors through 2050: A Review. Minerals, 13.","DOI":"10.3390\/min13101274"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"123299","DOI":"10.1016\/j.jclepro.2020.123299","article-title":"Global Wind Power Development Leads to High Demand for Neodymium Praseodymium (NdPr): A Scenario Analysis Based on Market and Technology Development from 2019 to 2040","volume":"277","author":"Deng","year":"2020","journal-title":"J. Clean. Prod."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"11807","DOI":"10.1021\/acs.est.2c02247","article-title":"Tracking Three Decades of Global Neodymium Stocks and Flows with a Trade-Linked Multiregional Material Flow Analysis","volume":"56","author":"Liu","year":"2022","journal-title":"Environ. Sci. Technol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"108009","DOI":"10.1016\/j.resconrec.2024.108009","article-title":"Self-Sufficiency of the European Union in Critical Raw Materials for E-Mobility","volume":"212","author":"Koese","year":"2025","journal-title":"Resour. Conserv. Recycl."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Leal Filho, W.L., Kotter, R., \u00d6zuyar, P.G., Abubakar, I.R., Eustachio, J.H.P.P., and Matandirotya, N.R. (2023). Understanding Rare Earth Elements as Critical Raw Materials. Sustainability, 15.","DOI":"10.3390\/su15031919"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"M\u00fcnchen, D.D., Stein, R.T., and Veit, H.M. (2021). Rare Earth Elements Recycling Potential Estimate Based on End-of-Life NdFeB Permanent Magnets from Mobile Phones and Hard Disk Drives in Brazil. Minerals, 11.","DOI":"10.3390\/min11111190"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"100884","DOI":"10.1016\/j.cogsc.2024.100884","article-title":"An Overview of NdFeB Magnets Recycling Technologies","volume":"46","author":"Kaya","year":"2024","journal-title":"Curr. Opin. Green Sustain. Chem."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"135992","DOI":"10.1016\/j.cej.2022.135992","article-title":"Strategies and Options for the Sustainable Recovery of Rare Earth Elements from Electrical and Electronic Waste","volume":"442","author":"Ramprasad","year":"2022","journal-title":"Chem. Eng. J."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1016\/j.procir.2016.03.013","article-title":"Comparative Life Cycle Assessment of NdFeB Magnets: Virgin Production versus Magnet-to-Magnet Recycling","volume":"48","author":"Jin","year":"2016","journal-title":"Procedia CIRP"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"3796","DOI":"10.1021\/acs.est.7b05442","article-title":"Life Cycle Assessment of Neodymium-Iron-Boron Magnet-to-Magnet Recycling for Electric Vehicle Motors","volume":"52","author":"Jin","year":"2018","journal-title":"Environ. Sci. Technol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"117573","DOI":"10.1016\/j.jclepro.2019.07.048","article-title":"Recycling and Substitution of Light Rare Earth Elements, Cerium, Lanthanum, Neodymium, and Praseodymium from End-of-Life Applications\u2014A Review","volume":"236","author":"Omodara","year":"2019","journal-title":"J. Clean. Prod."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Ishak, S.A., Yunas, J., and Hashim, A.M. (2023, January 28\u201330). The Effects of Particle Sizes of Neodymium Iron Boron Microstructure on the Magnetic Characteristics. Proceedings of the 2023 IEEE Regional Symposium on Micro and Nanoelectronics (RSM), Langkawi, Malaysia.","DOI":"10.1109\/RSM59033.2023.10327334"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"250","DOI":"10.1016\/S0925-8388(02)00496-6","article-title":"Influence of Particle Size of Iron Powder on the Microstructure of Nd\u2013Fe\u2013B Alloy Powder Prepared by Reduction-Diffusion","volume":"346","author":"Sidhu","year":"2002","journal-title":"J. Alloys Compd."},{"key":"ref_22","unstructured":"Friebe, P., Suponik, T., Nuckowski, P.M., Matusiak, P., and Kowol, D. (2025). Spos\u00f3b Odzysku Metali z Zu\u017cytych Dysk\u00f3w Twardych. (Patent Application: P.452083), The Patent Office of the Republic of Poland."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"e28","DOI":"10.7717\/peerj-matsci.28","article-title":"A Study on Demagnetization Heat Treatment of Waste Neodymium Iron Boron (NdFeB) Magnets by Using Computer Simulation","volume":"5","author":"Kim","year":"2023","journal-title":"PeerJ Mater. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2541","DOI":"10.1007\/BF01174525","article-title":"A Study of Nd-Fe-B Magnets Produced Using a Combination of Hydrogen Decrepitation and Jet Milling","volume":"24","author":"McGuiness","year":"1989","journal-title":"J. Mater. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"898","DOI":"10.1017\/S143192761300648X","article-title":"Applications of the Hybrid Ion Milling Method to Neodymium Magnets","volume":"19","author":"Shdiara","year":"2013","journal-title":"Microsc. Microanal."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1016\/0925-8388(94)01291-O","article-title":"Application of High Energy Ball Milling to the Production of Magnetic Powders from NdFeB-Type Alloys","volume":"217","author":"Jurczyk","year":"1995","journal-title":"J. Alloys Compd."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"132671","DOI":"10.1016\/j.jclepro.2022.132671","article-title":"Circular Economy Practices in the Waste Electrical and Electronic Equipment (WEEE) Industry: A Systematic Review and Future Research Agendas","volume":"365","author":"Pan","year":"2022","journal-title":"J. Clean. Prod."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"12441","DOI":"10.1021\/acs.est.5b02264","article-title":"Tracking the Flow of Resources in Electronic Waste\u2014The Case of End-of-Life Computer Hard Disk Drives","volume":"49","author":"Habib","year":"2015","journal-title":"Environ. Sci. Technol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1007\/s10163-014-0347-6","article-title":"Enabling the Recycling of Rare Earth Elements through Product Design and Trend Analyses of Hard Disk Drives","volume":"17","author":"Ueberschaar","year":"2015","journal-title":"J. Mater. Cycles Waste Manag."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"25532","DOI":"10.1007\/s11356-021-17761-3","article-title":"Efficient Recovery of Rare Earth Elements from Discarded NdFeB Magnets by Mechanical Activation Coupled with Acid Leaching","volume":"29","author":"Mao","year":"2022","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"105154","DOI":"10.1016\/j.hydromet.2019.105154","article-title":"Recovery of Valuable Metals from NdFeB Magnets by Mechanochemically Assisted Ferric Sulfate Leaching","volume":"191","author":"Binnemans","year":"2020","journal-title":"Hydrometallurgy"},{"key":"ref_32","unstructured":"(2025, March 18). TRADING ECONOMICS. 20 Million Indicators from 196 Countries. Available online: https:\/\/tradingeconomics.com\/."},{"key":"ref_33","unstructured":"(2025, April 25). SMM. Steel, Aluminum, Nickel, Rare Earth, New Energy, Copper Prices Charts and News-Shanghai Metals Market. Available online: https:\/\/www.metal.com\/."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/12\/2697\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:48:26Z","timestamp":1760032106000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/12\/2697"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,6,8]]},"references-count":33,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2025,6]]}},"alternative-id":["ma18122697"],"URL":"https:\/\/doi.org\/10.3390\/ma18122697","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,6,8]]}}}