The Circular Economy: A View from the Front
Geoscientists might feel our work is detached from the circular economy. Frances Wall and colleagues discuss efforts to create a national road map for the circular economy of technology metals – one that has geoscience at its heart
The circular economy (CE) is intimately linked with future sustainable economic development. While some geoscientists might think the CE has little to do with them, there are many ways in which geoscience contributes to the development of more circular flows of materials.
Currently, the UK is almost entirely reliant on imports for our supply of technology metals (those needed for emerging technologies, including electric vehicles, solar photovoltaics, wind farms and energy storage) and there is no single reference point for how these metals flow through our economy. Key examples of technology metals include lithium, cobalt, rare earth metals, tin, tungsten and indium, but there are many others. To transform our current linear flows of technology metals into a more sustainable, circular system of assured supply, reuse and recycling, we must first track the existing flows. Here we discuss efforts by the Met4Tech Centre team (www.met4tech.org/), a UKRI-supported partnership of world-leading researchers who aim to maximise opportunities for the provision of technology metals and lead materials stewardship. The team contains researchers from business, social studies, law, chemistry, materials science, engineering – and several geoscientists. The aim is to make key research interventions across the value chain and then together with industry partners, build a national road map for a technology metals circular economy.
The Circular Economy concept
The term circular economy was first used in the late 1980s/1990, but the concepts come from as much as forty years ago, and involve thinking about the flows of materials through an economy, reduction of waste, and a symbiosis between industry and ecology (Ekins et al., 2019). Since then, the term has developed and evolved and is now in popular use in industry, government, and many disciplines of research.
For many people, their first thought when they hear ‘circular economy’ is probably recycling; collecting up waste and doing something useful with it. While important, recycling is only the backend of CE – CE is much more than this. It asks for a whole systems approach (Fig. 1), or as the Ellen MacArthur Foundation says, a ‘systems solution framework that tackles global challenges like climate change, biodiversity loss, waste, and pollution’. The championing, study, and popularising of the CE by the Ellen MacArthur Foundation, which formed in 2010, has been key to the growth of this concept.
CE principles are now widely proposed as a solution to the impacts of materials use and we are seeing increasing uptake of these principles in government and industrial strategy. The European Union was one of the first to use CE principles as a key platform for its economic growth and research, development and innovation. In the UK, the Department for Environment, Food and Rural Affairs uses CE principles as a primary way to reduce waste and the carbon footprint associated with materials use. This was one of the drivers for setting up the UKRI National Interdisciplinary Circular Economy Research (NICER) programme – a four-year £30 million investment programme aimed at moving the UK towards a circular economy, of which Met4Tech is one key part.
Within the NICER programme there are five centres focusing on construction materials, textiles, chemicals, major metals and technology metals (Met4Tech) with a coordinating centre – the CE-Hub (www.ce-hub.org). By bringing industry, academics, policy makers and civil society together, the ambition of the programme is to deliver research, innovation, and the evidence base to move the UK towards a resilient, inclusive, restorative and competitive UK circular economy.
Given the importance of the extractive industry in providing all non-biological raw materials, it would be a pity if it was left ‘hanging off the end’ (albeit the front end) of CE programmes, and mistakenly perceived as being contrary to CE principles. The idea that the ‘circular economy will end mining’ is certainly a phrase that is heard from time to time. However, while the ‘virtuous circles’ of materials that recycle into new products time and again may look encouraging, they don’t show an accurate picture of the significant inflows of new raw material resources that will be needed to combat climate change and to attain the sustainable development goals.
Application to exploration and mining
The Ellen MacArthur Foundation defines the CE on the principles of ‘designing out waste and pollution, keeping products and materials in use, and regenerating natural systems’. All of these can be applied to exploration and mining.
Consideration of how to design out waste and pollution is possible even at the first desk-study phase of an exploration campaign by incorporating this criterion into the choice of the ore types to target. Techniques such as life-cycle assessment can be incorporated into mine design even before the definitive feasibility study, giving plenty of options to make substantial improvements.
Keeping products and materials in use is certainly possible. Even though they are only extracted from Earth once, metals are some of the most sustainable materials and with good stewardship, they can be used multiple times again (Smith & Wentworth, 2022). According to the International Aluminium Institute, 75% of all the aluminium ever produced is still use today. Smelter/refiners are key players and mining companies that do this second stage of producing metals or compounds ready for manufacturing can take part in this form of CE. Some specialist metals such as rare earths are hardly re-used or recycled at all. Although technical solutions to recycling are on the way, better stewardship demands more joined-up thinking throughout the value chain, including innovation to ensure longer use and re-use.
While the term ‘regeneration’ in figure 1 was intended, presumably, to refer to the biological cycle, it also applies to mining operations, where regeneration of natural systems to preserve and enhance biodiversity is an important aspect of a responsible operation. The gold mine at Otjikoto in Namibia is an example of a mine with an extensive rewilding scheme that enhances the environment now and will still provide employment after mining ends.
The importance of critical minerals
The critical minerals agenda has been useful in securing the involvement of geoscience in CE research. Many of the raw materials deemed critical (economically important but vulnerable to supply disruption) are the specialist technology metals needed to manufacture clean technologies such as electric vehicles, wind turbines, fuel cells and solar panels. Influential reports from the International Energy Agency and The World Bank emphasize how much supply of these technology metals must increase in coming years to meet climate change targets. For cobalt, this could be up to five times more, and for lithium, this might be up to 40 times more (IEA, 2021).
There is no doubt that recycling materials, whilst vital, cannot meet growing demand – new exploration and mining is essential. Any integrated approach to a new, circular system for these materials must involve new primary supply, and, given the required accelerated use of clean technologies to achieve net zero, this supply must meet high standards of responsible mining. The door is open to whole systems thinking, including exploration, extraction, processing, manufacturing, use, re-use, remanufacturing, and recycling.
The UK Critical Minerals strategy published in July 2022 (BEIS, 2022),contains both the desire to accelerate new production, particularly where there are opportunities to mine lithium, tin, tungsten and copper in the UK, and the need for better CE approaches, especially to capture end-of-life critical materials.
The data gap
A problem that very quickly arises when thinking about the CE is how to find data about the stocks and flows of metals and their original minerals. Information on the original raw materials is published by geological surveys but data for the in-use stocks and flows are more difficult to establish. Reasonable data are available for some of the major metals, but for the specialist technology metals, data are few and far between. The Met4Tech team is researching how to create a virtual data observatory for the UK, applying the geological skills of raw materials information at the British Geological Survey to acquire knowledge throughout the whole value system.
Mine waste is probably the first thing that geologists think of when considering how to apply CE to mining. It is the world’s largest waste stream, with estimates in the region of 100 billion tonnes of solid waste from the primary production of mineral and metal commodities every year (Tayebi-Khorami et al., 2019). All mining companies would like to reduce this burden. There are a number of avenues being explored to do this including reassessment of tailings and other waste products of mining as a source of value, re-mining the wastes using techniques such as bioleaching, improved resource efficiency through identification of additional value streams, and reducing resource sterilisation during operations.
Value streams are not just metalliferous products but can include aggregates from waste rock, sand-products from crushed gangue material, land space from remediation of tailings and waste rock, water from dewatering activities and heat from implementation of heat exchangers. There is even the possibility of using mine tailings, particularly those associated with mafic and ultra-mafic magmas, as feedstock for enhanced rock weathering and mineral carbonation to aid atmospheric CO2 drawdown (e.g. Bullock et al., 2021; James et al., 2021).
More difficult but a better CE solution is to avoid producing the waste in the first place, for example, by developing new mining engineering technologies for selective mining of narrow vein ores or solution mining that dissolves out only the minerals of interest.
Co-products and by-products
Many metals, especially technology metals, are recovered as by- or co-products of the more abundant major industrial metals. Cobalt is a common co-product of sedimentary-copper mines, while tellurium, selenium and indium are hidden in sulphide ores of copper, zinc and gold until recovered as by-products during smelting. The dependency of many critical metals on other major metals has been discussed for some time and is epitomised from the metallurgy point of view by the metals wheel concept developed by Markus Reuter (2018).
The Met4Tech team is taking a CE view more from the front – beginning with exploration geology and considering potential co/by-products as an essential part of the metallogenic character of a deposit (Fig. 2). Our research is identifying the economic and regulatory barriers to improved by-product production and advocating for improved material efficiency through the inclusion of by/co-products in resource and economic planning at all stages of mining. By utilising cutting-edge machine learning and automated mineralogy, we are tracking by-products from ore in the ground through the mining and beneficiation cycle, developing workflows that can plug the by-product data gap in the extractive industry.
Met4Tech interventions across the mining and beneficiation process aim to highlight data gaps and develop new procedures, processes and technologies to promote efficient sustainable extraction of essential technology metals.
CE thinking can go further. In Met4Tech, we have been researching alongside the exploration for the technology metals: tin, tungsten and lithium, and geothermal energy in Cornwall and West Devon. There are more than ten active projects in this 150-km-long region of the UK. Each focuses on developing its own deposit(s) through the various stages of exploration. Our research is looking at synergies between the projects, including the possibilities for more joint solutions for ores and wastes in future mines, as well as possible reprocessing of old mine wastes (see box ‘Cornwall Case Study’). For example, cassiterite (SnO2) is the main tin mineral in all the granite-related ore deposits in Cornwall and West Devon, giving the potential for collaboration between projects, and for the incorporation of legacy waste from previous mining if the cassiterite was not removed completely. In conjunction with the exploration companies, the Met4Tech team are carrying out mineralogical analyses of mine wastes and life-cycle assessments of potential processing combinations to test these possibilities. Integrating with existing businesses and landscape and, in this region, a UNESCO mining landscape world heritage site is also part of the CE approach. There are also good possibilities for joint metals and geothermal energy production, including lithium extraction from geothermal brines and using new and old mines as sources of geothermal energy.
Perhaps an obvious point is that if projects ‘dig and ship’ ore concentrate to other countries for processing, the opportunities for the region to benefit from the rest of the value chain and recycling are lost. So, in addition to embedding circular economy practices within day-to-day company operations, it is important to identify and develop the core nodes, such as the smelter/refiner stage, that enable material recirculation in a CE industrial ecosystem.
Cornwall case study
In SW England, there is a potential nexus between stocks of tailings, from historical copper and tin mining and contemporary china clay (kaolin) extraction activities, and a resurgence in interest in minerals projects. There have been initiatives by various companies to adopt more circular practices, with the co-production of metals, heat and energy to enable more value to be captured from single sites, and reassessment of wastes as potential feedstocks for mineral processing plants.
For example, in the Innovate UK-funded ‘Combined production of Lithium and China Clay in Cornwall’ project three companies explored the co-production of lithium and china clay in Cornwall. The St Austell Granite is an important source of china clay and also hosts significant grades of lithium within Li-mica minerals. These minerals are separated from kaolinite during the production of china clay and stored at tailing facilities or sold as by-products in the aggregate industry.
The value of the natural resources in SW England is broader than just the main metal of interest: by- and co-product metals and materials, aggregate production, water treated to alleviate acid mine drainage, mine water geothermal, under- and above-ground space and infrastructure are all potential sources of value. Whether it is possible for this value to be captured requires further feasibility studies, collaboration between different industries, and holistic ‘people-planet-prosperity’ cost-benefit analysis.
Interdisciplinary research and solutions
Geoscientists (and miners) often use the kind of CE diagram (Fig. 3) that is produced by the European Institute of Innovation & Technology (EIT) Raw Materials Knowledge and Innovation Communities (KIC). However, this is a technology focused diagram that emphasises the production and recycling of the materials parts of the CE but condenses all of the circular cascades of use, repair/recover and reuse (the highest value part of the system) into one small segment. The CE is about technical solutions and business models, and social behaviours. Research on raw materials is just one theme in Met4Tech; other colleagues are devising manufacturing solutions to facilitate better recycling, applying life-cycle assessment to determine the most environmentally advantageous solutions, making social studies of road mapping and responsible innovation, creating agent-based models to test future flows of technology metals, and considering regulatory measures to improve circularity of metals flows. This takes us back to the aim of Met4Tech in bringing all these aspects together to create a national roadmap that can lead the UK towards a new circular economy for technology metals – one that highlights good practice, opportunities and challenges.
An integrated and circular value chain for the technology metals will be needed for the energy transition and will be essential both for security of supply and sustainability. CE approaches should start by thinking about what we really need, and how to make best use of the materials. To combat climate change, we know that we need to bring greater quantities of many technology metals into circulation very quickly. Geoscientists sit right at the front of this new technology metals circular economy system, and right from the first stages of exploration can contribute to more circular and sustainable solutions.
Frances Wall, Professor of Applied Mineralogy, Camborne School of Mines, University of Exeter, UK @franceswallcsm
Philip Bird, Research Associate in Mineral Processing, Centre for Sustainable Resource Extraction, University of Leicester, UK
Eva Marquis, Research Fellow, Camborne School of Mines and Environment and Sustainability Institute, University of Exeter, UK
Carol Pettit, Senior Impact and Partnership Development Manager, Camborne School of Mines, University of Exeter, UK
Gawen Jenkin, Professor of Applied Geology, Centre for Sustainable Resource Extraction, University of Leicester, UK
Karen Hudson-Edwards, Professor in Sustainable Mining, Camborne School of Mines and Environment and Sustainability Institute, University of Exeter, UK
- BEIS (2022) Resilience for the Future: The UK’s critical minerals strategy. UK Government; gov.uk/government/publications/uk-critical-mineral-strategy
- BGS (2022) UK criticality assessment of technology critical minerals and metals; bgs.ac.uk/download/uk-criticality-assessment-of-technology-critical-minerals-and-metals/
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- Tayebi-Khorami, M. et al. (2019) Re-Thinking Mining Waste Through an Integrative Approach Led by Circular Economy Aspirations. Minerals 9 (5), 286; https://doi.org/10.3390/min9050286
- The Circular Economy Centre for Technology Metals (Met4Tech); https://met4tech.org/
- The Ellen McArthur Foundation; https://ellenmacarthurfoundation.org/
- The International Energy Agency (2021) The Role of Critical Minerals in Clean Energy Transitions. Part of World Energy Outlook Flagship report; iea.org/reports/the-role-of-critical-minerals-in-clean-energy-transitions
- The National Interdisciplinary Circular Economy Research (NICER) Programme; https://ce-hub.org/nicer-programme/
- The World Bank (2020) Minerals for Climate Action: The Mineral Intensity pf the Clean Energy Transition; https://pubdocs.worldbank.org/