Highlights
- Brazilian researchers developed a sustainable method to extract rare earth elements from discarded hard disk drive magnets using low-cost acetic acid.
- The process achieved 95.3% total rare earth element recovery, with potential to transform electronic waste into valuable ‘urban mines’.
- The breakthrough could improve global supply chain resilience for critical materials used in wind turbines, electric vehicles, and high-performance magnets.
A team at the University of São Paulo (opens in a new tab) has developed a promising method to extract rare earth elements (REEs) from discarded hard disk drive (HDD) magnets using acetic acid, a low-cost and biodegradable leaching agent. The study, led by Fernanda Fajardo Nacif Petraglia (opens in a new tab), Professor Denise Crocce Romano Espinosa, and colleagues, appears in Waste Management (Vol. 205, 2025) and may mark a significant step forward in the economics and sustainability of REE recycling.
The researchers optimized a hydrometallurgical leaching process using 3.0 mol/L acetic acid at 50 °C for 2 hours and a solid-to-liquid ratio of 1/12. Under these conditions, they achieved a total REE recovery of 95.3%, including 18.4 g/L neodymium, 2.9 g/L praseodymium, and 1.2 g/L dysprosium. These elements are essential for wind turbines, electric vehicles, and high-performance magnets.
Using kinetic modeling, the study revealed a mixed control mechanism—dominated by both chemical reactions and diffusion barriers created by hydrogen bubble formation. Compared to conventional sulfuric acid routes, the acetic acid method proved to be competitive in terms of cost (~€46.84/kg processed) and environmentally advantageous, with lower toxicity and potential for renewable sourcing.
Obsolete HDD magnets, which contain an average of ~29 wt% REEs, are increasingly seen as “urban mines.” The study confirms their viability as a secondary source and aligns with UN Sustainable Development Goals on circular economy, sustainable production, and waste reduction.
Challenges remain, however, particularly the co-leaching of iron and cobalt. Further development of purification methods, such as oxidative precipitation or solvent extraction, will be necessary to reach commercial-grade REE output. While lab-scale results are robust, the researchers estimate that full-scale commercialization will require at least 3–5 years, contingent on pilot plant development, downstream integration, and regulatory life-cycle analysis.
The study was supported by FAPESP and CAPES, with no declared conflicts of interest.
This breakthrough adds momentum to the global push for sustainable REE recovery. If scaled, the process could enhance supply chain resilience and reduce reliance on primary extraction from geopolitically concentrated sources, such as China.
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