Recovery of Platinum Group Metals from Spent Automotive Catalysts: A Review of Processes and Challenges

Platinum group metals (PGMs: Pt, Pd, Rh, Ru, Os, Ir) are critical strategic metals. Spent automotive catalysts (SACs) represent one of the most significant secondary sources of PGMs, and their recovery is essential for alleviating the supply-demand imbalance. In the recycling chain, pyrometallurgical processing of SACs generates Fe-Si-based alloy concentrates (termed Fe-Si-PGMs), serving as an important yet challenging intermediate resource for PGM recovery. This review first summarizes the pyrometallurgical and hydrometallurgical processes used for recovering PGMs from SACs, before shifting its focus to the treatment technologies for PGMs in Fe-Si-PGMs alloy. These techniques, including direct extraction, extraction following desilication (via alkaline roasting, slagging, or hydrometallurgical routes), and in situ mechanochemical extraction, are critically evaluated in terms of their advantages and limitations. Furthermore, given that the accurate quantification of trace-level yet high-value PGMs represents another key challenge in the recovery chain due to complex sample matrices, this work systematically outlines and compares the analytical methods commonly employed, such as fire assay, spectroscopic and mass spectrometric techniques, electrochemical methods, and alkali fusion. Finally, several recommendations are provided regarding PGM recovery from SACs, with emphasis on Fe-Si-PGMs alloy processing and analytical methods for PGMs.