Recovery strategy of platinum group metal ruthenium (Ru) from spent SiC catalyst: Combined process of oxidation roasting and Fe smelting capture.

Platinum group metal Ru has been widely employed in catalysis due to its unique catalytic capabilities. Ru extraction from spent catalysts classified as hazardous waste possesses significant commercial and environmental value. However, the chemical inertness of SiC and the encapsulation of Ru by surface SiO2 layers pose a significant challenge to the efficient recovery of precious metals. Consequently, developing a technology to recover Ru from SiC substrates is essential for the sustainable use of Ru resources and can additionally enhance the application of SiC in catalysis. In this study, the synergistic process of oxidation roasting and Fe smelting capture was discussed to recover Ru from the SiC catalyst. The oxidation behavior of spent catalyst under CO2, air, and O2 atmospheres was first investigated. During roasting, SiC particles converted to SiO2, while the conversion of Ru to RuO2 was limited (<2.53%). Roasting in pure oxygen yielded a weight gain exceeding 35%, and the distinct SiO2 peak in the XPS spectrum confirmed complete conversion of SiC. The coexistence of Ru and RuO2, coupled with the encapsulation of Ru species by the formed SiO2, made smelting collection the preferred strategy for separating Ru from the silica matrix. Under optimized slag composition (CaO/SiO2 = 0.31, 15% Al2O3) and conditions (1500 ℃, 10% Fe, 10% C), an Fe-Ru alloy with 7.19% Ru was produced, corresponding to an enrichment ratio > 5 and a Ru recovery rate of 97.8%. The strategy presented in this work enables a simple and efficient recovery of Ru from SiC-based materials, providing a feasible technical route for reclaiming valuable metals from SiC catalyst supports.