Platinum-group metals (PGMs) include platinum, palladium, rhodium, iridium and other precious metals. Featuring outstanding high-temperature resistance, corrosion resistance, excellent catalytic activity and superior chemical stability, they are indispensable strategic materials in chemical industry, metallurgy, environmental protection, precision manufacturing and other fields. Given the scarcity of PGM mineral resources and high mining costs, and the fact that PGM alloy waste generated in industrial applications still retains extremely high metal value, regeneration and recovery have become core approaches to supplement PGM resources, reduce industrial costs and realize green circular development. Industrial PGM alloy waste features diverse categories, scattered sources and variable compositions. Targeted differential regeneration and recovery processes have been developed in the industry to achieve efficient purification and cyclic reuse of such waste.
1. Classification and Recovery Logic of Platinum-Group Metal Alloy Waste
Based on waste sources, component purity and pollution levels, PGM alloy waste is divided into two major categories: single clean waste and complex mixed waste, which require significantly different recovery and processing workflows adapted to respective process systems.
Some industrial waste alloys are collected through fixed-point specialized recycling with uniform components and stable ratios. They only develop surface contaminants during long-term service or lose their original functions due to damaged physical structures and degraded mechanical properties, while the precious metal components of the alloy matrix remain unchanged. Such waste can be recycled with simple processes without complex decomposition and purification. The core treatment logic is impurity removal, purification and physical restoration. After thoroughly eliminating surface and internal contaminants, the waste can be remelted and reprocessed into new devices for reuse, presenting high recycling efficiency, low cost and minimal loss.
In contrast, the vast majority of PGM alloy waste in the market comes from diverse sources and is accumulated in mixed states. Alloys of different types and ratios are blended together, accompanied by a large number of impurities such as base metals, silicates, carbon deposits and oil stains, resulting in complex component systems and inconsistent purity. Such waste cannot be directly reused and must undergo systematic hydrometallurgical procedures, including dissolution and solution transfer, impurity separation, selective separation of individual PGMs, and intensive refining. Through these multi-step processes, impurities are gradually removed and single high-purity PGMs are obtained to realize resource regeneration.
2. Core Purification and Recovery Processes for Conventional Waste
Mature physical and chemical purification technologies have been developed for reusable clean waste alloys to precisely remove various contaminants while maximally preserving the original alloy properties. Targeted treatment for conventional pollutants boasts mature technology and strong adaptability, serving as the core method for simple regeneration and recovery.
High-temperature oxidation treatment is adopted to remove organic contaminants such as oil stains and high-temperature carbon deposits on workpiece surfaces. High-temperature calcination fully oxidizes, decomposes and volatilizes organic impurities without damaging the structure and components of the alloy matrix. For base metal impurities (e.g., iron, copper and nickel) mixed in alloys, boiling leaching with single or mixed acid solutions including hydrochloric acid, sulfuric acid and nitric acid is applied. Utilizing the high solubility of base metals in strong acids, the process selectively dissolves and removes base metal impurities while avoiding PGM loss.
Alkali soaking or hydrofluoric acid dissolution is used to eliminate silicon impurities and silicate attachments on and inside waste alloys. After the above comprehensive purification treatments, qualified alloy materials can be directly remelted, shaped and reprocessed into industrial devices to complete closed-loop regeneration.
3. Typical Waste Recovery Case: Regeneration Technology of Spent Pt-Pd-Rh Catalytic Nets
Pt-Pd-Rh alloy catalytic nets are core components in ammonia oxidation chemical production and one of the main sources of industrial PGM alloy waste, with highly representative regeneration and recovery processes in the industry. Such catalytic nets are woven from high-precision alloy wires with a diameter of only 0.06–0.09 mm, featuring ultra-thin, ultra-fine structure and high specific surface area to meet the requirements of high-efficiency catalytic reactions.
The mainstream industrial models include ternary and binary alloys, with classic formulations of Pt-4Rh-3.5Pd ternary alloy and Pt-(5-10)Rh binary alloy. Adapted to domestic chemical production conditions, China mostly adopts high-palladium Pt-Pd-Rh-M quaternary alloys (M represents an active auxiliary metal) to further improve catalytic stability and service life.
The scrapping of catalytic nets is mainly attributed to high-temperature working losses and impurity contamination. Ammonia oxidation proceeds under continuous high-temperature oxidation conditions. Long-term operation causes slight oxidative volatilization of platinum and rhodium, forming loose and rough “cage-like” structures on the surface of ultra-fine alloy wires. This destroys the original dense microstructure, significantly reduces the strength and toughness of the alloy, and leads to embrittlement, damage and fracture. Meanwhile, trace base metal impurities continuously adhere to and penetrate the alloy surface, blocking catalytic active sites and sharply reducing catalytic activity. The degraded catalytic nets can no longer meet production requirements and must be regenerated.
Fine specialized regeneration processes are applied to spent Pt-Pd-Rh catalytic nets. First, pre-treatment is conducted to remove surface carbon deposits, oil stains and superficial impurities. The alloy is then dissolved to transfer platinum, palladium, rhodium and other precious metals into the solution system. Solvent extraction, selective precipitation, ion exchange and other technologies are adopted to separate platinum, palladium, rhodium and auxiliary metals step by step and completely remove residual impurities. Finally, intensive refining, melting, wire drawing and weaving are performed to manufacture new high-precision catalytic nets. The process realizes 100% cyclic reuse of precious metals and greatly reduces the consumption cost of precious metals in chemical production.
4. Industrial Value and Development Trend of Platinum-Group Metal Regeneration and Recovery
Compared with primary mineral smelting, PGM regeneration and recovery have prominent advantages including lower energy consumption, less pollution, shorter production cycle and higher utilization rate, serving as a core support for the green and low-carbon development of the precious metal industry. With the growing consumption of PGMs in industrial fields and the continuous increase in stockpiled waste alloys, efficient and refined regeneration processes can effectively alleviate China’s high external dependence on PGM resources, realize closed-loop recycling of industrial resources and reduce production costs for enterprises.
The industry is upgrading from traditional extensive impurity removal and recovery to refined, short-process, high-purity and low-loss technologies. The popularization of new technologies such as centrifugal extraction, precise selective separation and low-temperature clean dissolution has further improved the recovery rate and product purity of PGMs, promoting the high-quality development of the precious metal recycling industry. As a professional enterprise deeply engaged in the precious metal recycling sector, Henan Yusai Precision Machinery Co., Ltd. specializes in technical services and equipment manufacturing for the refining and purification of rare precious metals, including gold, silver, platinum, palladium, rhodium, iridium and ruthenium. The company focuses on optimizing efficient and eco-friendly regeneration processes, providing reliable technical support and advanced equipment solutions for high-purity recovery and cyclic utilization of platinum-group metal alloy waste. In the future, intelligent and green regeneration and recovery technologies will become the key to efficient utilization of PGM resources and sustainable development of the industrial sector.
