Synergistic Smelting and Recovery of Platinum Group Metals from Metallurgical By-Products and Spent Catalysts: A Review of Traditional Technologies and Microwave Metallurgy

Platinum group metals (PGMs)—comprising platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), and osmium (Os)—are indispensable strategic materials for key industries, including automotive manufacturing, petrochemical engineering, and the new energy sector. Given the uneven global distribution of primary PGM reserves and the widening supply–demand gap, recovering PGMs from secondary sources—primarily metallurgical by-products and spent catalysts—has become a strategic priority. synergistic smelting, leveraging “multi-feedstock complementarity” and “multi-technology coupling,” offers an efficient approach to overcoming challenges associated with secondary resources, such as low grades, complex matrices, and refractory separation. This paper systematically reviews the technological evolution of synergistic smelting for PGMs recovery, focusing on three aspects: the characteristics and processing bottlenecks of PGMs-bearing secondary resources, the development trajectory of traditional metallurgical technologies, and innovative breakthroughs in microwave-assisted synergistic smelting. A comparative analysis between traditional and microwave-based technologies is conducted across four dimensions: resource adaptability, technical performance, environmental sustainability, and industrial maturity. Finally, the core challenges currently confronting microwave-assisted synergistic smelting and future directions for industrial demonstration are elaborated on. This study serves as a comprehensive reference for the efficient and sustainable recovery of PGMs, with significant implications for the circular economy and strategic resource security.