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Highlights • Various methods for precious metals recycling from WEEE are reviewed. • Various methods for PGMs recycling from spent catalysts are reviewed. • Advantages and environmental impacts of recycling technologies are discussed. • Considerations on environment-oriented technologies have been proposed. Abstract Precious metals are widely applied in many industry fields due to their excellent corrosion resistance, good electrical conductivity and high catalytic activity. However, the reserves of precious metals falls short of the production globally. The rapid generation of end-of-life products has become the significant resources of precious metals. Among these products, electronic waste (e-waste) and spent catalysts are more concentrated since they account for over 90% of precious metals in industry. This article provides an overview of various technologies on the recovery of precious metals from e-waste and spent catalysts. It shows that recycling technologies have been significantly improved in recent years. The recycling processes have transferred from leaching by aqua regia, cyanide and chlorine in acid solution to less pollution agents leaching. Environment-oriented technologies have been raised great attention in precious metals recycling. The advantages and environmental impacts of these recycling technologies have been discussed in detail. However, there are still some challenges for future promotion. In order to achieve the environment-friendly and sustainable recycling for precious metals with high recovery rate, several considerations have been proposed. [ABSTRACT FROM AUTHOR]

• 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]

• 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]