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Platinum group metals (PGMs) are indispensable for the automobile, petrochemical, energy, and national defense industries. However, the mineral resources of PGMs are extremely scarce in China, and the contradiction is prominent between the supply and demand of the resources. Therefore, recycling PGMs becomes an important measure to ensure the safe supply of PGMs and support the high-quality development of related industries. This study analyzes the supply and application of PGMs, clarifies the supply and demand trend of the PGMs market, and sorts out the recycling technologies of PGMs. The hydrometallurgical process includes cyanidation as well as hydrogen chloride combined oxidant method. The pyrometallurgical process includes capture by lead,copper, matte, and iron. The research and application of the pyro-hydro-metallurgical recycling process for PGMs are elaborated from the aspects of the roasting-leaching, iron capture-acid leaching, and low-temperature iron capture-electrolysis-centrifugal extraction processes. The low-temperature iron capture-electrolysis-centrifugal extraction process follows the research idea of low-temperatureiron capture. Through the design of slags with a low melting point, the iron capture temperature is reduced from beyond 1800 ℃ to around 1400 ℃. The enriched Fe-PGM alloy is further enriched by electrolysis, and Pd, Pt, and Rh are successively obtained through centrifugal extraction and purification, realizing the short-process separation and purification of PGMs. This process has the advantages of green, high efficiency, and low cost. Focusing on the high-quality development of the PGM recycling industry, we propose the following suggestions: (1) conducting basic research and technical breakthroughs centering the entire process of PGM enrichment, separation and purification, as well as pollution prevention and control; (2) accelerating the construction of a full-chain standards system for PGM recycling and a green and low-carbon industrial ecological environment; and (3) improving the Internet Plus capabilities through the entire business links to realize the intellectualization of the whole recycling-processing-reuse process.

• Simple evaluation for platinum group metals (PGMs) recovery from primary and secondary sources was made. • Various separation technologies for PGMs recycling from secondary resources are reviewed. • Advantages, challenges and outlook of recycling technologies are discussed. • Considerations on further promotion have been proposed. In the past decades, the demand for platinum group metals (PGMs) has increased rapidly in various applications such as electronics, chemical engineering, biomedical devices, and automotive catalytic converters. Recovery of PGMs from secondary resources is necessary for addressing the supply issues. The migration of PGMs from solid to liquid streams is irreplaceable for achieving high-purity products. Hence, it is a meaningful issue to reduce resource depletion and avoid environmental pollution during separation processes. This paper systematically reviews various improvements and new technologies for the separation and purification of PGMs, including solvent extraction, membranes separation, supercritical fluids, solid-phase extraction, photoreduction, and electrochemical methods. The separation mechanism and optimized process parameters are summarized. Particularly, the advantages, challenges, and perspective are highlighted in terms of commercial applications. This study aims to present the current research for scholars, and to identify a promising PGMs separation method that is safe and effective. Finally, several recommendations have been proposed for the further promotion of separation technologies. [ABSTRACT FROM AUTHOR]

Platinum group metals (PGMs) are regarded as strategic metals due to high melting point, corrosion resistance and catalytic activity. They are widely employed in renewable energy, petrochemical industry, vehicles and pharmaceutical engineering. However, the supply and demand of PGMs are facing challenges stemming from rarity and unequal distribution across the globe. This review aims to delve into the supply-demand of PGMs to elucidate primary applications and pinpoint current or projected shortfalls in the supply chain. The future demand for PGMs indicates a significant increase, particularly within the hydrogen sector. It is anticipated that Pt and Ir consumption in fuel cell vehicles and proton exchange membrane electrolysis will reach 143 tons and 38 tons by 2050, respectively. Production of PGMs is far from meeting demand. Sustainable development strategies, including recycling, substitution and innovative technologies, are proposed to address this contradiction. Recycling serves as a strategy to increase PGMs supply. Nevertheless, recycled PGMs accounted for approximately 26 %. Substitution represents a pathway to decrease the PGMs contents in products. The Pt load in fuel cells declined from 1.0 g kW−1 in the 1990s to 0.3 g kW−1 nowadays. Innovative technologies can mitigate the PGMs demand. Electric vehicles, solid oxide fuel cells and electrolysis cells provide promising alternatives for PGMs intensive industry. Ultimately, key future development directions for PGMs are outlined. The emphasis should lie on enhancing PGMs recovery efficiencies and intensifying research into catalytic mechanisms. Notably, ensuring the secure supply of PGMs will facilitate the advancement of renewable and sustainable energy. [Display omitted] • The supply and demand for PGMs is serious imbalance. • The demand for PGMs is forecasted, especially hydrogen industry. • PGMs sustainable strategies include recycle, substitution, innovative technologies. • Challenges and suggestions for PGMs sustainable development are raised. [ABSTRACT FROM AUTHOR]

• Iron was used as collector for PGMs recovery. • Recovery efficiency of PGMs was 99.25 % by iron melting collection. • The formation of ferrosilicon was avoided at 1300–1400 °C. • The effect of slag have been studied in detail. • The recovery efficiency was over 99 % at 50 kg scale experiments. Automobile catalysts sector is the largest consumption field of platinum group metals (PGMs) worldwide, and they are the most important secondary resources of Pt, Pd, and Rh once they reach the end of life. However, recycling PGMs from spent automotive catalysts is of great difficulty due to their complex physicochemical characteristics and low concentrations. A highly efficient technology for recovery of Pt, Pd, and Rh by iron melting collection was proposed. Owing to the same face-centred cubic structure and close atomic radius, iron powder is used as collector since Fe and PGMs can form continuous solid solution. PGMs are concentrated and formed Fe-PGMs alloy phase at a relatively low temperature of 1300–1400 °C through adjustment of slag compositions. The principles of slag design were put forward, and the effects of basicity, slag compositions and collector dosage on the recovery efficiency of PGMs were studied. Factsage 7.0 software (CRCT-Thermfact and GTT-Technologies) was used to calculate slag viscosity and simulate slag reaction equilibrium during the melting process. The recovery efficiency of PGMs was 99.25 % under the optimized conditions: mass ratio of CaO/Na 2 O=35:20, CaF 2 5 wt.%, Na 2 B 4 O 7 8.5 wt.%, collector Fe 15 wt.%, and 5 wt.% C, where the concentration of Pt, Pd and Rh in slag phase were 2.398, 3.879, and 0.976 g/t, respectively. Meanwhile, the formation of ferrosilicon (FeSi 2 , FeSi) was avoided. 50 kg pilot-scale experiments also achieved over 99 % recovery efficiency of PGMs. [ABSTRACT FROM AUTHOR]