Current situation of platinum group metal recovery in spent catalysts

Platinum group metals (PGMs) play a vital role in the automotive, petrochemical and electronic devices industries due to their unique physical properties and excellent catalytic activity, rendering them indispensable strategic resources for the country. However, China's PGM mineral resources are scarce with low ore grades and high mining costs. Consequently, recovering PGMs from secondary resources, particularly the large quantities of spent PGM catalysts has become the primary source of these metals. Based on the operating conditions, current PGM enrichment processes can be divided into pyrometallurgical and hydrometallurgical processes. Pyrometallurgical processes feature high processing capacity and short process flows, making them suitable for large-scale operations, but they are energy-intensive and cause considerable environmental pollution. In contrast, hydrometallurgical processes operate under milder reaction conditions and good selectivity for specific materials, though they involve longer process flows and high reagent consumption. After enrichment, PGMs in the solution require purification and refining. The precipitation method is applicable for enriching solutions with high metal ion concentrations but tends to introduce impurities. Solvent extraction yields high-purity products, yet the extractants are often toxic and volatile which increases operational difficulty. Ion exchange achieves high separation efficiency and low pollution, but it is costly and severely restricted by the solution system. This paper summarizes common enrichment processes and conducts detailed analysis of their respective advantages and disadvantages. It also overviews different purification processes and elaborates on their merits and demerits. On this basis, the paper outlines future research directions for PGM recovery from spent catalysts, providing new insights for promoting efficient recycling of secondary PGM resources and developing economical, environmentally friendly, and intelligent recovery processes.