Integrating pyrometallurgy and slag design: A novel strategy for enhanced platinum extraction from hybrid wastes (spent automotive catalysts/electric arc furnace dust)

To address the increasing demand for platinum (Pt) and the accumulation of hazardous waste, this study proposes a novel and sustainable pyrometallurgical co-smelting strategy for recovering Pt from spent automotive catalysts (SACs) using electric arc furnace dust (EAFD) as a co-smelting agent. Thermodynamic analysis confirmed the feasibility of reducing Pt oxides and sulfides to their metallic form under high-temperature, reductive conditions, enabling efficient alloying with iron (Fe). A five-component slag system (SiO 2 –Al 2 O 3 –CaO–MgO–FeO) was designed to lower the melting temperature and viscosity, thereby improving the separation efficiency of slag and alloy. Through systematic single-factor experiments, the effects of alkalinity (CaO/SiO 2 ), EAFD addition amount, reducing agents amount, and smelting temperature on Pt recovery were investigated. Optimal recovery (96.4%) was achieved under the conditions of CaO/SiO 2 = 0.7, 20 wt% EAFD addition amount, 6 wt% reducing agents amount, and a smelting temperature of 1550°C. Microstructural characterizations using X-ray diffraction and scanning electron microscopy and energy dispersive spectroscopy revealed that Pt was predominantly incorporated into the Fe matrix through substitutional solid solution mechanisms. Furthermore, the resulting slag exhibited a dense, amorphous glassy microstructure, indicating excellent environmental stability and inertness, thereby minimizing the risk of secondary pollution. Overall, this integrated co-smelting approach not only offers a technically viable and environmentally benign method for the high-efficiency recovery of Pt from SACs but also establishes a novel paradigm for the cross-sectoral recycling of hazardous industrial residues such as EAFD. The proposed strategy thus holds significant potential for advancing circular economy practices within the waste management industries.