Ultradeep Enrichment of Platinum Group Metals Using Fe ₂ O ₃ as Oxygen Carrier for Base Metals Oxidation and Removal

ABSTRACT The recovery of platinum group metals (PGMs) is pivotal for a circular economy, yet current hydrometallurgical routes heavily rely on corrosive acids and generate hazardous effluents, violating the principles of green chemistry. In our previous studies, PGMs were recovered via an iron capture process. The concentration of PGMs in Fe‐PGMs alloys ranges from 0.1 to 2.0 wt.%, which requires ultradeep enrichment before the separation and purification of PGMs. Herein, a solvent‐free and safe enrichment strategy for Fe‐PGM alloys was developed using earth‐abundant Fe ₂ O ₃ as a solid oxygen carrier. The oxygen transfer mechanism across the slag/metal interface was elucidated, revealing that Fe ₂ O ₃ accelerates base metal oxidation. Through slag optimization, efficient phase separation was achieved. Under optimal conditions, over 95% of base metals were removed, yielding a remarkable PGM enrichment factor of 22.63 with a recovery efficiency of 99.9%. Crucially, environmental impact analysis confirms that this route significantly outperforms traditional methods, achieving an E‐factor of 40.0 (in contrast to over 1000 for traditional acid‐leaching processes) and a superior safety profile (ISI = 5) by eliminating solvent consumption and hazardous emissions. This work presents a benign‐by‐design approach utilizing earth‐abundant Fe ₂ O ₃ as a solid oxidant, offering a sustainable alternative to high‐pressure oxygen blowing and acid leaching.