Mechanochemical greenhouse gas capture into silicate-based rocks

This PhD project will explore how mechanochemical carbon dioxide capture processes can be translated into industrial ore processing systems for three major ore deposits (copper, iron and platinum group ores). The research will investigate how three variables, the feed material particle size, the water content during crushing and the crushing methodology, affect the capture of CO2 and other greenhouse gases such as CH4, NO2, and SO2. The project will deploy the experimental methods used in Stillings et al. 2023 to optimise GHG capture based on these variables. To mimic industrial rock processing, rocks crushed in the laboratory will be compared in terms of their surface area, grain size and surface properties, with rocks crushed in industrial ore processing facilities to provide information for scale-up of the process. The PhD student will experimentally evaluate the key variables that affect the mechanisms and total mass of trapped greenhouse gases, as well as determine their long-term stability in the environment. Experiments will explore how reaction conditions can be altered to increase the efficiency of GHG trapping or to reduce the energy use during processing.
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.
This PhD project will quantify the capture potential of current ore treatment processes, identify the stages of ore processing with the highest capture potential and understand how altering distinct factors within ore processing can optimise the trapping process and increase GHG capture.

Aims and Objectives:
- Understand how different ore types (copper, iron, platinum group) respond to mechanochemical GHG capture.
- Identify how the mechanochemical capture process can be integrated into current ore processing facilities where parameters such as water content, particle feed size and comminution method vary.
- Determine the most suitable stages in an ore processing facility where mechanochemical carbon capture can have the greatest impact on emissions reduction.
- Explore the similarities and differences in comminution techniques used in laboratories and at industrial facilities to identify suitable bench-scale industrial comminution analogues.