Demand for rare earth permanent magnets (REPMs) has grown drastically the past decades and is expected to increase further due to their use in electronics, electric vehicles and wind turbines. Rare earth supply challenges have increased the urgency to recycle End-of-Life (EoL) REPMs. This paper examined the development of global EoL REPM recycling by applying the Technological Innovation Systems (TIS) framework, assessing temporal development and dynamics between different aspects of the system. The analysis showed an acceleration of recycling innovation activities since 2013, evidenced by e.g. research and development initiatives, (commercial) pilot plants and media and policy attention. Activities were identified globally, with regional concentration of some functions. Innovation in EoL REPM recycling is mainly driven by policies and positive expectations, while entrepreneurial activities also contribute. The EoL REPM recycling TIS holds potential for further growth, if sufficient supplies of recyclable material are secured and a demand for recycled magnets is created. These goals can be achieved by developing the capacity to handle a diversity of waste products, by making recycling cost-effective, or by finding other marketing approaches for recycled magnets. This would enable the emergence of an independent market. Together with other circular economy solutions, EoL REPM recycling can contribute to a more sustainable and resilient magnet supply.

Securing the availability of enough metals to fulfill demand is a critical societal concern. Models of metal supply systems can help enhance our understanding of these systems and identify strategies to reduce material criticality and improve resilience. In this work, we introduce a novel approach to modeling metal supply systems, using nickel as a case study. Our approach combines system dynamics modeling, in which various feedback loops influence future outcomes, with the higher sectoral and geographical detail of industrial ecology (IE) methods and data on individual mines. We also include extensive uncertainty analyses through exploratory modeling and analysis. Using this combined modeling approach, we explore the development and resilience of the global nickel supply system between 2015 and 2060 under various uncertainties and policy levers. Our results show that incorporating feedback effects leads to more realistic demand behavior and resource depletion patterns compared to traditional dynamic material flow analysis. Market feedback enhances resilience, but cannot fully offset criticality risks. Sectoral disaggregation reveals increased criticality risks due to the energy transition, which can be mitigated by increasing opportunities for substitution, product lifetime extension, recycling, exploration, capacity expansion, and by-product recovery. Geographical disaggregation highlights the resilience benefits of diverse supply sources, as well as the effects of changing regional market shares on sustainability impacts, ore grade variability, and by-product dynamics. Our combined modeling approach is a step toward prospective, dynamic criticality assessment, in which system changes and future risks are accounted for when determining material criticality and policy recommendations.

Tin is an important metal for society with a high risk of supply disruptions. It is, therefore, classified as a critical material in many parts of the world. An exception is the European Union, for which tin was classified as a non-critical material in 2023. However, there are many discrepancies in the literature regarding the definitions and values of the indicators used to determine tin criticality in general, and recycling indicators in particular. Values for end-of-life recycling rate (EoL RR) range between 20% and 75%, and values for end-of-life recycling input rate (EoL RIR) range between 11% and 32%. In this paper, we critically assess the circularity and criticality indicator values for tin and calculate new values using material flow analysis. The new values for tin recycling indicators are lower than those used in most previous research, with a global EoL RR of 16% and an EoL RIR of 11% in 2017. Based on the updated recycling values, combined with a highly concentrated supply, high import reliance, and difficult substitution, we argue that the European Union should classify tin as a critical material. This reclassification can lead to more policy attention for tin, which can help reduce the impact of future supply disruptions and increase the resilience of the European and global tin supply chains.