Presentation Information
[P2-29]Recycling of NdFeB magnets from hard disc drive scrap using HPMS and using recycled magnets in an automotive auxiliary motor
*Muhammad Awais1, Abeshaa Mahendran2, Jovey Farthing2, Robert Arnold2, Viktoria Kozak1, David Moule3, Harvey Smith3, Allan Walton1 (1. School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham, B15 2SE (UK), 2. HyProMag Limited, Tyseley Energy Park, The Fordrough, Hay Mills, Birmingham B25 8DW (UK), 3. ZF Automotive UK Limited, Blythe Valley Park, Solihull B90 8BG (UK))
Keywords:
NdFeB,Rare Earth Elements,Recycling,Electric Motor,Short Loop Recycling
Rare earth elements are at the top of the list of critical elements for the UK, EU, and US due to their use in the green energy transition [1-3]. Rare earths such as neodymium; are used to make the strongest permanent magnets known as neodymium-iron-boron (NdFeB) magnets. NdFeB magnets are commonly found in consumer electronics such as hard disc drives (HDDs), smartphones and loudspeakers. They also play a vital role in green technologies such as hybrid, electric vehicles and wind turbines. In recent years, the increasing popularity of electric cars and wind turbines has caused an increase in the demand for these magnets, leading to supply and price volatility risks.
The scrap containing NdFeB magnets can be a valuable resource to generate an additional supply to meet the growing demand. However, there are challenges surrounding the collection and segregation of scrap containing these magnets, recovery of the alloy powder with minimal contamination and cost-effective re-processing into new magnets. Previous work has shown that by using the hydrogen processing of magnetic scrap (HPMS) technology, NdFeB magnets from HDDs, automotive scrap and loudspeakers can be removed in the form of demagnetised powder and re-sintered into new magnets post-purification [4-6].
In this work, 100 kg of mixed source separated voice coil magnet assemblies (VCM) from HDDs were processed in the commercial HPMS vessel at 2 bar hydrogen pressure at room temperature. The composition of the liberated material was analysed showing 0.343 wt.% oxygen, 0.118 wt.% carbon and 0.45 wt. % nickel. The powder was sieved below 90 µm to remove the nickel coating and the purified powder was subsequently partially degassed, jet-milled, aligned, compacted and sintered at 1070 oC for 4 hours with the addition of 3 wt.% NdH3. The resulting recycled magnets had Br of 1.34 T and Hcj of 1279 kA/m and showed 0.159 wt.% oxygen, 0.119 wt.% carbon and 0.028 wt.% nickel.
The recycled magnets were machined to size and installed in an existing automotive auxiliary motor design. No changes to the motor design were made to adapt for use of recycled magnets. The motor showed performance within 3% of the minimum acceptable.
References
[1] Mudd, G. et al., (2024). UK 2024 Criticality Assessment, British Geological Survey OR/24/047. 235pp. Available from: https://www.ukcmic.org/downloads/reports/ukcmic-2024-criticality-assessment.pdf, accessed on 27.02.2025.
[2] European Commission, Study on the critical raw materials for the EU 2023, March 2023. available from https://op.europa.eu/en/publication-detail/-/publication/57318397-fdd4-11ed-a05c-01aa75ed71a1, accessed on 27.02.2025.
[3] US Department of Energy. Critical Materials Assessment, July 2023. Available from https://www.federalregister.gov/d/2023-16611, accessed on 27.02.2025.
[4] Harris IR, Williams A, Walton A, Speight J. Magnet Recycling. United States patent US 8734714 B2. 27.05.2014.
[5] Walton, A.; Yi, Han; Rowson N.A.; Speight J.D.; Mann V.S.J.; Sheridan R.S.; Bradshaw A.; Harris I.R.; Williams A.J. The use of hydrogen to separate and recycle neodymium-iron-boron-type magnets from electronic waste. Journal of Cleaner Production (2015), Pages 236 – 241.
[6] Jönsson, C.; Awais, M.; Pickering, L.; Degri, M.; Zhou, W.; Bradshaw, A.; Sheridan, R.; Mann, V.; Walton, A. The extraction of NdFeB magnets from automotive scrap rotors using hydrogen. Journal of Cleaner Production (2020), Article number 124058.
The scrap containing NdFeB magnets can be a valuable resource to generate an additional supply to meet the growing demand. However, there are challenges surrounding the collection and segregation of scrap containing these magnets, recovery of the alloy powder with minimal contamination and cost-effective re-processing into new magnets. Previous work has shown that by using the hydrogen processing of magnetic scrap (HPMS) technology, NdFeB magnets from HDDs, automotive scrap and loudspeakers can be removed in the form of demagnetised powder and re-sintered into new magnets post-purification [4-6].
In this work, 100 kg of mixed source separated voice coil magnet assemblies (VCM) from HDDs were processed in the commercial HPMS vessel at 2 bar hydrogen pressure at room temperature. The composition of the liberated material was analysed showing 0.343 wt.% oxygen, 0.118 wt.% carbon and 0.45 wt. % nickel. The powder was sieved below 90 µm to remove the nickel coating and the purified powder was subsequently partially degassed, jet-milled, aligned, compacted and sintered at 1070 oC for 4 hours with the addition of 3 wt.% NdH3. The resulting recycled magnets had Br of 1.34 T and Hcj of 1279 kA/m and showed 0.159 wt.% oxygen, 0.119 wt.% carbon and 0.028 wt.% nickel.
The recycled magnets were machined to size and installed in an existing automotive auxiliary motor design. No changes to the motor design were made to adapt for use of recycled magnets. The motor showed performance within 3% of the minimum acceptable.
References
[1] Mudd, G. et al., (2024). UK 2024 Criticality Assessment, British Geological Survey OR/24/047. 235pp. Available from: https://www.ukcmic.org/downloads/reports/ukcmic-2024-criticality-assessment.pdf, accessed on 27.02.2025.
[2] European Commission, Study on the critical raw materials for the EU 2023, March 2023. available from https://op.europa.eu/en/publication-detail/-/publication/57318397-fdd4-11ed-a05c-01aa75ed71a1, accessed on 27.02.2025.
[3] US Department of Energy. Critical Materials Assessment, July 2023. Available from https://www.federalregister.gov/d/2023-16611, accessed on 27.02.2025.
[4] Harris IR, Williams A, Walton A, Speight J. Magnet Recycling. United States patent US 8734714 B2. 27.05.2014.
[5] Walton, A.; Yi, Han; Rowson N.A.; Speight J.D.; Mann V.S.J.; Sheridan R.S.; Bradshaw A.; Harris I.R.; Williams A.J. The use of hydrogen to separate and recycle neodymium-iron-boron-type magnets from electronic waste. Journal of Cleaner Production (2015), Pages 236 – 241.
[6] Jönsson, C.; Awais, M.; Pickering, L.; Degri, M.; Zhou, W.; Bradshaw, A.; Sheridan, R.; Mann, V.; Walton, A. The extraction of NdFeB magnets from automotive scrap rotors using hydrogen. Journal of Cleaner Production (2020), Article number 124058.