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Neodymium being an expensive strategic metal indispensable for our society, the key issue is to secure its supply and make its usage sustainable. However, with less than 1% of it currently being recycled, we are far from achieving this. Although some work is underway to recycle electrical engines’ large Nd-based magnet alloys, little attention has been given to recycling small Nd-containing ceramic-based components, despite their 12% share of the Nd market. Herein, we demonstrate an economically viable Nd recycling process from such components found in electronic wastes. We tackled the issue of high Nd dilution in complex e-wastes through the upstream deployment of simultaneous disassembly, machine vision and multi-energy X-ray transmission sorting (first-of-its-kind), followed by precise beneficiation in virtue of the difference in magnetism, density and fracture toughness. The resulting concentrates are mainly dielectric ceramics (BaO-Nd2O3-TiO2), containing 38.3 wt% of Nd. Although ceramics are refractory in general, Nd can be simply leached in concentrated HNO3 from these dielectrics with high selectivity under optimized conditions. Subsequently, Nd can be recovered by oxalate precipitation while 60% of HNO3 can be regenerated. To elaborate on the mechanism of the leaching, the related kinetics, thermodynamics and bonding nature were investigated through theoretical computations. The overall Nd recovery efficiency reaches 91.1% ending up with commercial-grade Nd2O3 (> 99.6%). More importantly, the recycling route is estimated profitable within four years based on conservative margins. This work provides a promising strategy to recover rarely recycled strategic metals towards a closed-loop design.
Xia et al. (Fri,) studied this question.