Avaliação do beneficiamento e recuperação de materiais críticos de ímãs de NdFeB pós-consumo

Abstract

The increase in Waste Electrical and Electronic Equipment (WEEE) generation has become a global concern, driven by rapid technological advancement and the growing consumption of electronic devices. The improper disposal of this waste not only has the potential to cause negative environmental impacts but also results in the loss of valuable resources, including rare earth elements (REEs), which are essential for the production of modern technologies. In this context, this study evaluated the feasibility of recycling NdFeB magnets from post-consumer hard disk drives (HDDs) through the recovery of these materials. The hydrogen decrepitation (HD) method was employed as an initial step for the extraction and separation of the magnets. This process was applied with the goal of recovering materials for the subsequent production of recycled magnets using the conventional powder metallurgy route. The powder preparation stage, prior to compacting the test specimens, was adapted to reduce environmental impact and occupational risks by eliminating the use of solvents during milling. This modification aimed to minimize the generation of hazardous liquid effluents and workers’ exposure to toxic substances, while also simplifying the process. NdFeB magnets from WEEE were characterized using ICP-OES, XRD, XRF, and SEM techniques. The use of HD demonstrated a significant increase in the grinding efficiency of the magnets, rising from 25.33% to 73.33%. This percentage refers to the amount of material effectively ground within the same milling time. However, the sintering stage yielded unsatisfactory results, as the absence of solvents during milling affected particle size distribution and specimen compaction, promoting oxidation and compromising the cohesion of the resulting magnets. The research highlights the need for strict control of processing conditions to minimize these effects. The SEM micrographs indicate that HD is a promising approach for NdFeB magnet recycling. Nevertheless, adjustments are required to enable the effective production of recycled magnets, emphasizing WEEE recovery as a key strategy for reducing the extraction of critical raw materials and promoting material circularity.