ABSTRACT
The extraction and consumption of metals and minerals have grown exponentially in recent decades. This leaves significant challenges, namely, managing the depletion of non-renewable resources and various environmental burdens arising from resource extraction. To address these challenges and sustainable development goals (SDGs) requires a transition towards a circular economy (CE). By drawing on the life cycle system perspective of industrial ecology, CE proponents propose three main approaches – reduce, reuse, and recycle. They are designed to be implemented in the “fabrication and manufacturing”, “use”, and “waste management and recycling” stages of metals’ life cycle, respectively. Among them, the recycling strategy, or usually termed “urban mining”, in the downstream stage is now the most widely applied approach for metals. As for the extraction of metals from natural ore reserves, the recycling of metals from urban in-use stocks consists of four major processes: (1) the estimation of urban in-use stocks and end-of-life (EoL) flows; (2) the collection of EoL products; (3) the dismantling of EoL products and the separation of metals; and (4) the smelting and refining of secondary metals. We demonstrate that the potential and importance of urban mining for metals will keep growing over time, and describe the work needed in each process. The CE transition is essential for achieving the “SDG 12-- Responsible Consumption and Production”, especially for metals and minerals that have the potential to be infinitely recycled and reused. However, more recycling infrastructure, eco-design technologies toward recycling, reusing, and remanufacturing, as well as more effective policy incentives, are needed to stimulate CE transition.
