This project aims to develop a new technology for capturing carbon into waste rock powders that are naturally formed during mining and aggregate production operations. We aim to use mechanochemical reactions, which occur during rock crushing, to permanently trap CO2 from industrial exhaust gases as a means of carbon capture. During crushing, energy is instantaneously released (as charged particles and photons) when the chemical bonds in the rock are broken. We use this mechanochemical energy to trap CO2. Our recent research, published in Nature Sustainability, showed that if you crush silica-rich rocks, such as granite and basalt, in CO2 gas instead of air, the CO2 can become permanently trapped, via a process of chemical sorption, within the crystal lattice of the crushed particles. This project will build on our early research. We will explore the effects of temperature, crushed particle size and initial rock water content on the amount of CO2 trapped per unit mass of crushed rock. We will also investigate gas stream composition. Our previous research used pure CO2: here we will crush rocks within realistic CO2-rich effluent gases from industries such as cement production, biomass power production, gas and hydrogen production from natural gas. We will evaluate the carbon savings from our technology using life cycle analysis. Finally, we will explore the potential for (1) the final rock powders to be used as a partial cement replacement product, and (2) co-production of valuable metals from the CO2-rich rock powders. This research project could have a major impact on our ability to meet net zero carbon targets by 2050. Worldwide, at least 40 billion tonnes of silicate-rich rocks are crushed every year by the mining and quarrying industries. If we can adapt current rock crushing processes to trap CO2, with very little extra energy expenditure (other than that used to transport the CO2), then this could be used to trap greenhouse gases from 'hard to decarbonise' industries. Based on our published early research findings, at least 0.4MtCO2 of thermally-stable and insoluble CO2 can be trapped for every 100Mt of saleable crushed aggregate. We estimate that, if this technology was developed and adopted worldwide, it could capture ~0.5% of global CO2 emissions, or 175MtCO2 annually: this is equivalent to the CO2 trapped by a mature forest the size of Germany.

The Circular Economy (CE) is a revolutionary alternative to a traditional linear, make-use-dispose economy. It is based on the central principle of maintaining continuous flows of resources at their highest value for the longest period and then recovering, cascading and regenerating products and materials at the end of each life cycle. Metals are ideal flows for a circular economy. With careful stewardship and good technology, metals mined from the Earth can be reused indefinitely. Technology metals (techmetals) are an essential, distinct, subset of specialist metals. Although they are used in much smaller quantities than industrial metals such as iron and aluminium, each techmetal has its own specific and special properties that give it essential functions in devices ranging from smart phones, batteries, wind turbines and solar cells to electric vehicles. Techmetals are thus essential enablers of a future circular, low carbon economy and demand for many is increasing rapidly. E.g., to meet the UK's 2050 ambition for offshore wind turbines will require 10 years' worth of global neodymium production. To replace all UK-based vehicles with electric vehicles would require 200% of cobalt and 75% of lithium currently produced globally each year. The UK is 100% reliant on imports of techmetals including from countries that represent geopolitical risks. Some techmetals are therefore called Critical Raw Materials (high economic importance and high risk of supply disruption). Only four of the 27 raw materials considered critical by the EU have an end-of-life recycling input rate higher than 10%. Our UKRI TechMet CE Centre brings together for the first time world-leading researchers to maximise opportunities around the provision of techmetals from primary and secondary sources, and lead materials stewardship, creating a National Techmetals Circular Economy Roadmap to accelerate us towards a circular economy. This will help the UK meet its Industrial Strategy Clean Growth agenda and its ambitious UK 2050 climate change targets with secure and environmentally-acceptable supplies of techmetals. There are many challenges to a future techmetal circular economy. With growing demand, new mining is needed and we must keep the environmental footprint of this primary production as low as possible. Materials stewardship of techmetals is difficult because their fate is often difficult to track. Most arrive in the UK 'hidden' in complex products from which they are difficult to recover. Collection is inefficient, consumers may not feel incentivised to recycle, and policy and legislative initiatives such as Extended Producer Responsibility focus on large volume metals rather than small quantity techmetals. There is a lack of end-to-end visibility and connection between different parts of techmetal value chains. The TechMet consortium brings together the Universities of Exeter, Birmingham, Leicester, Manchester and the British Geological Survey who are already working on how to improve the raw materials cycle, manufacture goods to be re-used and recycled, recycle complex goods such as batteries and use and re-use equipment for as long as possible before it needs recycling. One of our first tasks is to track the current flows of techmetals through the UK economy, which although fundamental, is poorly known. The Centre will conduct new interdisciplinary research on interventions to improve each stage in the cycle and join up the value chain - raw materials can be newly mined and recycled, and manufacturing technology can be linked directly to re-use and recycling. The environmental footprint of our techmetals will be evaluated. Business, regulatory and social experts will recommend how the UK can best put all these stages together to make a new techmetals circular economy and produce a strategy for its implementation.