The researchers propose that employing microbial mineral carbonation could potentially offset over 30% of a mine site’s annual greenhouse gas emissions if implemented across the entire operation.
Explaining the concept, Professor Ian Power from Trent University points out that ore processing leaves behind valuable minerals in mine waste, such as tailings. Microbial processes offer a solution by liberating these minerals while simultaneously sequestering CO₂. For instance, certain microbes produce acids that can leach minerals from tailings, a process known as bioleaching.
Moreover, microbial processes can facilitate carbonate minerals’ formation, effectively locking carbon dioxide away within their crystal structure—a stable and long-term solution for greenhouse gas storage. This microbial mineral carbonation process accelerates the conversion of CO₂ into carbonate minerals much faster than natural weathering processes.
Their research, outlined in a paper published in Plos Biology, illustrates how microbial processes, including those involving cyanobacteria, accelerate carbonate mineral precipitation reactions. Tests on mine wastes from a diamond mine show that cyanobacteria contribute significantly to mineral weathering and subsequent microbial mineral carbonation, potentially offsetting a substantial portion of greenhouse gas emissions.
Power emphasizes that while electrification of mine operations is crucial for reducing carbon footprints, microbial processes offer a passive and energy-efficient approach to carbon sequestration.
Dr. Jenine McCutcheon from the University of Waterloo highlights the effectiveness of microbial mineral carbonation compared to abiotic methods, demonstrating up to 17.7 times more carbon storage when considering associated cyanobacteria biomass.
Beyond carbon sequestration, implementing microbial processes can also mitigate the risk of residual metals entering waterways from mine tailings. Power assures that these processes can be contained within mine sites, eliminating concerns about environmental contamination.
The team advocates for scaling up their experiments to pilot projects at mine sites, stressing the importance of industry engagement to advance this technology toward large-scale deployment. They suggest conducting larger-scale field experiments to refine rates and reduce uncertainties surrounding CO₂ mineralization acceleration.
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