Abstract
Achieving low-carbon development in the mining sector is fundamental for global carbon emissions abatement,especially considering the growing demand for mineral resources.Currently,the energy foot-print of mines emerges as the main carbon contributor.While cleaner energy sources have the potential for reducing emissions,transitioning to these sources remains challenging.This study presents a practical CO2 mitigation strategy for underground mining by integrating bacteria into shotcrete to enhance exca-vation.The findings demonstrate that bacteria can capture CO2 from the atmosphere,thereby increasing the carbonation reactions.X-ray diffraction (XRD),scanning electron microscope (SEM) and energy dis-persive spectrometer (EDS) analysis shows the captured CO2 present in the forms of calcite,vaterite,and aragonite.The formed carbonates intermingled with the precipitated calcium-silicate-hydrate (C-S-H) at relatively low bacteria additions,densifying the cementitious matrix and improving the mechan-ical properties.However,high bacteria concentrations lead to excess carbonates that consume C-S-H pre-cipitation,counteracting the benefits of carbonation and reducing mechanical strength.Optimal results were achieved with 0.3％ bacteria by mass fraction,potentially mitigating 0.34 kg/m2 of CO2,which is approximately equivalent 567 g of CO2 absorbed by 1 g of bacteria based on the effectiveness demon-strated in this study.These findings are crucial for advancing emissions control in mining and supporting climate goals outlined in the Paris Agreement.
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