Abstract
Platinum group metals (PGMs) are critical materials widely used in automotive catalytic converters and increasingly recovered from secondary resources. Conventional recycling methods, including pyrometallurgical and hydrometallurgical processes, often involve high energy consumption and complex processing steps. In this study, a thermochemical–magnetic approach for PGM recovery from spent automotive catalysts is investigated using FeCl 2 vapor treatment followed by magnetic separation. A milled catalyst obtained from a spent Toyota Mark II catalytic converter was treated with FeCl 2 vapor at 1200 K under an argon atmosphere, and the effect of the molar ratio n(FeCl 2 ):n(Fe):n(catalyst) was systematically examined. Under optimal conditions (2:1:1), selective formation of ferromagnetic Fe–PGM intermetallic phases enabled efficient separation of PGMs from the ceramic matrix. Approximately 71.9 wt% of the treated material was recovered as a magnetic concentrate. X-ray diffraction confirmed the presence of FePt and FePd phases in the magnetic fraction, while the non-magnetic residue consisted mainly of cordierite. The proposed method provides an effective pre-concentration step for PGMs and offers a simpler alternative to conventional recycling processes.