"Urban Mining" has potential for meeting China's circular economy goals

China categorizes metal stock from manufactured products at end-of-use as "anthropogenic minerals." Our study suggests this stock has potential to meet future demand of key critical metals.

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There has been growing debate about the extent to which mining of metals from natural sources should be expanded versus a focus on a "circular economy" through which reuse, remanufacturing or recycling could meet demand. The United Nations International Resource Panel has engaged with this matter in a recent report on mineral resource governance and concluded that recycling would increase considerably over the next 3 decades but would be inadequate to meet future growth in demand for green technologies. The World Bank's released a report last week on "Minerals for Climate Action" and concluded that: "Even with large increases in recycling — including a scenario where 100 percent end of life (EOL) recycling is achieved — there is still likely to be strong demand for primary minerals. This is especially the case for those minerals with the highest growth in demand, which lack existing material to recycle and reuse." Earlier research published in Nature by us in 2017 had concluded that for copper recycling was not likely to meet demand, and mining supply itself could be constrained due to errant exploration planning and conflicts.

However, in our recent paper published in Nature Communications, we turn our attention specifically to China which is the world's largest producer of numerous minerals and also the most populous consumer of key mineral products.  In this analysis with new data we consider three product groups, 30 products, and use the revised Weibull lifespan model to map the generation of anthropogenic mineral and 23 types of the capsulated materials by targeting their evolution from 2010 to 2050. Total weight of anthropogenic mineral on average in China reached 39 Mt in 2010, but it will double in 2022 and quadruple in 2045. Stocks of precious metals and rare earths will increase faster than most base materials. The total economic potential in yearly-generated anthropogenic mineral is anticipated to grow markedly from 100 billion US$ in 2020 to 400 billion US$ in 2050. Furthermore, anthropogenic mineral of around 20 materials will be capable to meet projected consumption of three product groups by 2050.

This research has important implications about balancing investment in primary mining versus "urban mining" from existing infrastructure and products. The importance of tracking metals in constructed and built products, while ensuring that they are not disposed or rendered into higher states of entropy is essential. Overall, the durability of products needs to be considered in concert with their declining energy and performance efficiency over time. In some cases the availability of such obsolescent and energy inefficient products for recycling stock maybe more ecologically beneficial than simply increasing their lifespan. It is also possible that more durable products are less recyclable and vice versa more recyclable products are less durable. Aggregate changes in demand for the particular material over time as well as whether the metal is being downcycled or not, will impact whether an equilibrium between recycling stock and material inputs for new products is possible.

Policies around encouraging a circular economy from anthropogenic mineral stocks for recycling should keep in mind concerns about rebound effects and aggregate consumption. Recycling, should not itself be used as an excuse or validation for excess consumption patterns. Furthermore, the techniques involved in recycling need to be considered in terms of their chemical intensity as well as occupational hazards in disassembly, particularly for electronic wastes. Better modularity of design of products can address these concerns to some degree to make disassembly easier and less noxious. In short, a systems dynamic approach to understanding the various aspects of primary and secondary material flows and overall consumption parameters is needed. Such an integrative approach and careful evaluation of urban anthropogenic mineral stocks can help us reach the targets of the United Nations' Sustainable Development Goal on Responsible Production and Consumption (SDG12).

Saleem H. Ali

Blue and Gold Distinguished Professor of Energy and the Environment, University of Delaware and GEF Science Panel

Saleem H. Ali is the Blue and Gold Distinguished Professor of Energy and the Environment at the University of Delaware (joint tenured appointments in Geography and the Joseph Biden School of Public Policy); Senior Fellow at Columbia University's Center on Sustainable Investment; and Honorary Professor at the University of Queensland (Australia). He is also a member of the United Nations International Resource Panel and the Scientific and Technical Advisory Panel of the Global Environment Facility. His latest book is Earthly Order: How Natural Laws Define Human Life (Oxford University Press, 2022) Twitter @saleem_ali