Hydrogen peroxide-based oxidation and pH-controlled precipitation for the recovery of non-cerium rare earth elements from permanent magnet waste

This case study presents a sustainable and scalable process for the recovery of non-cerium rare earth elements (non-Ce REE) from end-of-life neodymium–iron–boron (NdFeB) permanent magnets. The method involves the selective precipitation of cerium using hydrogen peroxide at pH 5.5 and a NaOH/REE weight ratio between 0.41 and 0.45. Under these conditions, cerium was effectively removed from the leachate with a precipitation yield exceeding 99 wt%. The resulting cerium-based precipitate was calcined at 900 °C, and subsequent leaching in 1 M HCl enabled the recovery of non-Ce REE, including neodymium, praseodymium, gadolinium and dysprosium, with a maximum recovery rate of 97.9 wt%. The cerium content in the final product was controlled between 0.07 wt% and 2.1 wt% by adjusting the precipitation temperature, allowing for the production of two distinct rare earth oxide streams. The process was validated using real leachates obtained from the recycling of industrial magnet waste, demonstrating its applicability in real-world scenarios. The use of environmentally benign reagents and well-established unit operations supports the industrial feasibility and environmental sustainability of the proposed method. The results highlight the potential of this approach for the recovery of critical raw materials in line with circular economy and decarbonisation goals, offering a viable solution for the sustainable management of rare earth resources in industrial recycling contexts. • H 2 O 2 -based process with pH control separates cerium from other REEs in acidic leachates from magnets. • Precipitation at pH 5.5 removes >99 % cerium while enabling selective recovery of Nd, Pr, Gd and Dy. • Post-precipitation calcination boosts cerium purity and aids REE recovery via differential leaching. • Validated with industrial NdFeB leachates, achieving up to 97.9 % recovery of non-cerium REEs.