Mineral Carbonation Using Mine Tailings - a Strategic Overview of Potential and Opportunities

This paper summarises the findings of a larger study commissioned by IEA GHG, recently published as Technical Report 2022-10. Mineral sequestration, also known as accelerated mineral carbonation (AMC), particularly of magnesium- (Mg) and calcium (Ca) -rich minerals represents one approach to storage of CO2 in a solid carbonate phase. AMC has been investigated in the laboratory and at natural analogue sites since the early 1990s as an important and intriguing CO2 emissions mitigation option for large-scale (> 0.1 Mt/year) CCS / CCU (carbon capture and storage / carbon capture and utilisation). In practice, the CCU / CCS distinction is made based on whether or not the material containing the carbon has a commercial application. In this study, the techno-economic viability of AMC, and the comparative maturity of the technologies are assessed and accounted for, based on publicly available information accumulated over the last three decades. Current price levels of CO2 emission rights – and the development of these – are an important driver behind the attention AMC is receiving. Integration with existing or earlier mining activities, such as the use of tailings and other residues for CO2 sequestration as solid carbonates would be advantageous from many perspectives. Apart from CO2 emission mitigation, removal of waste piles from mining sites, while simultaneously producing materials with market value, is an intriguing proposition. Although the production of large material streams may overwhelm existing markets, processing of waste rock and tailings with new, more efficient technologies at mining sites offers the possibility to recover highly valuable metals, even where present at low concentrations. Wider environmental implications such as (excessive) use of water also need to be taken into consideration. For this reason, life cycle assessment (LCA), in addition to public acceptance studies identifying social concerns, is essential to ensure that large-scale deployment of AMC is a viable option. There is – however – yet much to be done with many of the technologies that are under development before they can be considered technologically and economically feasible. Only one actor claims a technology readiness level (TRL) of 6 although it seems plausible that a TRL of 8-9 for commercial large-scale deployment could be attained during the next decade.