Extraction of PGMs from insoluble Fe-Si-PGMs alloy by combined thermochemical and mechanochemical leaching: Sustainable, efficient, and scalable

Platinum group metals (PGMs) are scarce critical materials, and recovering PGMs from spent automotive catalysts (SAC) is economically and ecologically important. However, dissolving the Fe-Si-PGMs alloy derived from SAC is challenging, impeding PGMs recovery. This study aims to develop a more sustainable, efficient, and scalable leaching scheme. We demonstrate efficient leaching of Fe-Si-PGMs alloy using a thermochemical combined with mechanochemical leaching method with a HCl + FeCl 3  + H 2 O 2 solution. Kinetics parameters studies optimize the leaching process. The main obstacles to leaching are the chemical inertness of the alloy and the SiO 2 encapsulation formed. Ultimately, efficient dissolution of 99 % Pd, 95 % Pt and 88 % Rh was achieved, increasing PGMs leaching by 17 % compared to single thermochemical leaching. Additionally, this work remedies the scalability limitations of mechanochemical leaching and provides valuable insights for PGMs recovery.