A comprehensive review on the distribution behaviors of precious metals through pyrometallurgical processes and implications for recycling

Precious metals (PMs), particularly platinum group metals (PGMs), are of strategic importance due to their high supply–demand imbalance, scarcity, and functionality in high-tech fields. The global supply of PMs is constrained due to the rising demand in clean energy applications. Therefore, the recycling of PMs from secondary resources can effectively alleviate the risk of supply shortages. Pyrometallurgical technologies have attracted considerable interest because of their high recovery efficiency, extensive processing capacity, and minimal wastewater production. To enhance the recovery efficiency of PMs and promote the development of the underlying theories and technologies for pyrometallurgical enrichment, this review provides a comprehensive overview of the distribution behavior of PMs between slag and metal, with a particular focus on gold, silver, platinum, palladium, rhodium, and ruthenium. The factors, including gas partial pressure, temperature, slag composition, matte grade, and halogen elements, which have an influence on PMs distribution coefficients, are considered when designing slag types and setting smelting conditions. The characteristics of e-waste and spent catalysts differ significantly from those of ores. The distribution behaviors of PMs determine the recycling of PMs from spent catalysts and e-waste. Finally, the prospects of pyrometallurgical PMs recycling technologies are presented.