As highly scarce strategic precious metals, platinum-group metals (PGMs) possess unique physical and chemical properties including high temperature resistance, corrosion resistance, excellent catalytic activity and stable electrical conductivity. They are indispensable core materials for high-end industry, high-tech industry, national defense, military industry and civil consumption. Restricted by the scarcity of primary mineral resources, high mining costs and severe ecological losses, the secondary recycling and reuse of PGMs has become a vital supplementary source of PGM supply and a core pathway for the green, low-carbon and sustainable development of the precious metal industry. Compared with primary mineral mining, the regenerative recycling of PGMs features simpler technological processes, shorter production cycles and lower comprehensive costs, while greatly reducing ecological damage caused by mineral exploitation, delivering significant economic, ecological and strategic values.
PGM secondary resources mainly refer to PGM-containing wastes retired, failed and eliminated from various application fields, covering industrial production, high-tech research and development, national defense, military industry and residential livelihoods. They are characterized by wide sources, diverse categories, uneven grades and varied physical and chemical properties. Most industrial secondary resources require regeneration and purification via professional metallurgical processes to be converted into reusable metals or compound products. In contrast, some civil secondary resources have special attributes and can be directly recycled and reused without metallurgical processing, forming a differentiated recycling and utilization system.
1. Classification and Application Characteristics of General PGM Secondary Resources
In terms of application scenarios and recycling processing methods, PGM secondary resources are divided into civil consumption secondary resources and industrial application secondary resources, with remarkable differences in their recycling and reuse modes.
Civil consumption secondary resources mainly include PGM jewelry, decorative ornaments, commemorative coins for daily civilian use, and platinum ingots for private financial reserve and collection. Such resources are strictly stored and well preserved, with no oxidation, loss or deterioration during long-term storage. Their metal purity and physical and chemical properties remain stable with almost no impurity contamination. Therefore, they require no metallurgical regeneration procedures such as crushing, dissolution and refining. Only under special circumstances including industrial raw material shortage and insufficient market supply, they can be centrally purchased and transferred to industrial production for reuse, serving as high-quality standby precious metal resources with low cost and high efficiency.
Industrial application secondary resources are the core subject of PGM recycling and reuse, widely generated in the whole industrial chain including traditional chemical industry, automobile manufacturing, electronic and electrical engineering, new energy, precision manufacturing, aerospace and military equipment. After long-term industrial service, these resources suffer from functional failure, impurity enrichment and structural loss, covering waste catalysts, industrial waste residues, production waste liquids, failed alloy components and scrapped precision parts. Featuring a wide range of grades and complex impurity components, they must be purified and restored through professional metallurgical regeneration technologies before industrial reuse. According to metal grade, impurity content and physical and chemical properties, industrial secondary resources are precisely classified into high-grade and low-grade categories, corresponding to completely different recycling process systems.
2. Reuse Technology and Application of High-Grade PGM Secondary Resources
High-grade secondary resources are industrial precious metal wastes with optimal quality and highest recycling efficiency, mainly referring to failed PGM elemental metals and alloy functional materials, as well as precious metal workpieces and components slightly contaminated by a small amount of impurities. They are characterized by high PGM content, pure main components, few harmful impurities, extremely low metal loss rate and high recycling value.
The core key of regeneration and recycling technology for high-grade secondary resources lies in efficient and rapid dissolution. Adopting mature hydrometallurgical processes, high-purity precious metal wastes are dissolved with precisely proportioned chemical reagents to rapidly prepare high-concentration, high-purity and low-impurity PGM complex solutions. On this basis, fine processes including extraction, ion exchange, precision precipitation and filtration refining are applied to remove trace impurities and separate and purify high-purity PGM elemental metals or high-precision metal compound products.
The regenerated products have purity and performance equivalent to those of PGMs extracted from primary minerals, which can be directly reused in high-precision fields such as high-end precision manufacturing, military devices, high-end catalysis and electronic chips, realizing closed-loop circulation. With short recycling procedures, low loss and stable product quality, this model is currently the most cost-effective and mature PGM regeneration method in the industrial field.
3. Reuse Technology and Application of Low-Grade PGM Secondary Resources
Low-grade secondary resources are the most widely produced and diverse PGM wastes in industrial scenarios, mainly including waste automobile exhaust catalysts, petrochemical and fine chemical waste catalysts, PGM-containing industrial waste liquids, smelting waste residues, electroplating wastes and retired electronic component wastes. These resources generally have low precious metal content, various non-precious metal impurities, complex matrix components and severe pollutant enrichment, making their recycling far more difficult than high-grade wastes and impossible to be directly dissolved and refined.
The regeneration and recycling process for low-grade secondary resources is more complex, forming a standardized procedure of “pretreatment and enrichment – precise dissolution – deep refining”. The core technical focus is early-stage impurity separation and precious metal enrichment. Firstly, pretreatment technologies such as pyrometallurgical smelting, hydrometallurgical leaching and screening separation are adopted to thoroughly separate a large number of non-precious metal impurities (copper, iron, nickel, aluminum, etc.) and inorganic and organic pollutants, eliminate invalid components to the greatest extent, significantly increase the PGM proportion in wastes, and prepare high-concentration precious metal concentrates.
After enrichment and purification, the high-quality precious metal concentrates are efficiently dissolved to prepare mixed PGM solutions. Subsequently, multi-stage extraction, separation and purification, crystallization reduction and deep refining processes are carried out to separate different types of PGMs one by one, and finally produce standard-compliant pure metals or special compound products. At present, this process enables the efficient resource utilization of low-value wastes such as waste catalysts and industrial residues with a recycling efficiency of over 95%. It effectively activates a large number of low-value industrial PGM resources and widely meets the raw material supply demands of mainstream industrial fields including automobile exhaust treatment, chemical production, new energy and environmental protection equipment.
4. Industrial Value and Development Significance of PGM Secondary Recycling and Reuse
Against the backdrop of global resource shortage, dual-carbon goal advancement and circular economy development, PGM secondary recycling and reuse has become a key support for the high-quality development of the precious metal industry. In terms of resources, secondary recycling alleviates the shortage and supply deficit of primary PGM mineral resources, broadens the supply channels of precious metal resources, and guarantees the raw material security of strategic industries such as high-end manufacturing, military industry and new energy. Economically, the regeneration and recycling process eliminates large-scale mining and mineral processing, greatly reduces production energy consumption and raw material costs, and improves enterprise benefits and industrial economic efficiency.
Ecologically, large-scale promotion of PGM secondary circulation can reduce ecological problems such as vegetation destruction, soil erosion and pollutant discharge caused by mineral mining, lower the environmental pollution risks of industrial solid waste and waste liquid, and conform to the green and low-carbon industrial development philosophy. In the future, with the continuous iteration and upgrading of regenerative metallurgy technologies, the recycling accuracy and efficiency of both high-grade and low-grade wastes will be continuously improved, and the application scenarios of PGM secondary resources will be further expanded. A complete closed-loop industrial system of “resource production – industrial application – regenerative recycling – cyclic reuse” will be gradually established, providing a stable and sustainable precious metal resource guarantee for the sustainable development of high-end manufacturing, new energy and environmental protection industries.
