Future trends and strategies of recycling high-tech metals from urban mines in China: 2015-2050

High-tech metals are necessary materials for strategic emerging industries but their primary ores are generally difficult to be extracted because of economic and technical limitations. Urban mines have become a potential pool of secondary high-tech metals, called high-tech urban mines (HUMs). It is important and urgent to make a dynamic evaluation to understand the potential and technical feasibility for HUMs development. In this study, we construct the strategic development index (SDI) from three aspects - resource, technology, and environmental (R-T-E) to assess HUMs in China from 2015 to 2050. Furthermore, development strategies are proposed based on the dynamic evaluation results. Here we show that, there are four patterns of future trends of HUMs in China sustainable growth, first increase and then decrease, continuous decline, and fading out. The distribution of HUMs in "R-T-E" shows a trend of polarization with continuously shrinks of the range along all the three indexes. According to the evaluation results, different strategies - key development strategy, digestion strategy, reserve strategy and transfer strategy - should be adopted to develop HUMs. Wind turbines, fluorescence lamps, smartphones, EVs, Li-ion batteries and computers will be main reservoirs of secondary high-tech metals for a long time, they should be the focus of technology, funds and policy from both the government and enterprises.