Recovery of Rare Earth Elements from Hard Disk Drives: Technologies, Challenges, and Circular Economy Perspectives

Rare earth elements (REEs), especially neodymium (Nd), praseodymium (Pr), and dysprosium (Dy), are crucial for modern technologies because they are necessary for high-performance permanent magnets used in electronics, renewable energy systems, and electric vehicles. The rapid expansion of digital technologies has led to a significant increase in electronic waste (e-waste), which presents both environmental challenges and opportunities for resource recovery. Hard disk drives (HDDs), commonly used for data storage, contain NdFeB permanent magnets that serve as a valuable secondary source of REEs within the emerging field of urban mining. Efforts to recover REEs from HDDs are gaining importance in both research and industry, with various methods being explored, including mechanical dismantling, pyrometallurgical processing, hydrometallurgical leaching and separation, and direct magnet-to-magnet recycling. Although there are promising developments, several technical and economic barriers remain, such as efficient magnet separation, selective extraction of rare earths, impurity control, process scalability, and environmental concerns. This critical review discusses current technologies for REE recovery from HDDs, comparing different processing approaches and evaluating their benefits, limitations, and technological readiness. Special emphasis is placed on integrating recycling into circular economy models, highlighting opportunities for resource efficiency, reducing primary mining, and ensuring a sustainable supply of critical materials. The review also identifies key knowledge gaps and research priorities needed to enable large-scale industrial recycling of HDDs.