NSF Award
2421036
The global energy transition from fossil fuels to renewable sources and the accompanying need for energy storage, especially for electric vehicles, are generating a massive demand for critical and conventional metals. Refining these metals from ore-bearing rocks leaves a colossal volume (i.e., 5-7 billion m3 per year) of residues that are typically impounded for long-term storage and disposal as high-water-content, hydraulic slurries referred to as ‘tailings’, which are retained by earthen dams. The stability of these tailings storage facilities has been a major challenge facing the mining industry and a safety concern to the public and the environment. In parallel, the mining industry must also address regulations to reduce its carbon footprint that currently contributes to 2-3 percent of total anthropogenic CO2 emissions. Research funded by this award will address these two issues simultaneously by studying carbon mineralization of tailings materials. Geomimetic carbonation will be studied and engineered to convert the gaseous CO2 into solid carbonates that can concurrently serve two purposes: 1) to permanently sequester CO2 within tailings storage facilities; and 2) to serve as a cementing agent for stabilizing the tailings. Therefore, the project will advance the fundamental science to accelerate anthropogenic carbonation, and evaluate this technology as a potential engineering solution to reducing the risk of mine tailings failures. The project also contributes to mitigating effects of climate change by reducing the carbon emissions across the mining industry.<br/><br/>This research project’s goal is to study the anthropogenic carbonation process to stabilize mine tailings and hence create fundamental knowledge on the coupled yet competing and counteracting processes of consolidation versus cementation/CO2 mineralization occurring in both legacy and active tailings storage facilities. The specific goals are to uncover the effects of geomimetic carbonation on the mechanical stabilization of mine tailings and, hence, to devise an innovative approach to offset greenhouse gas production in the mining industry while simultaneously improving the stability of tailings storage facilities. Therefore, the research project will contribute to advancing sustainability, environmental protection, and circular economy, generating significant impacts on the environment and human society at multiple scales and dimensions. The project involves an integrated experimental and computational study of the kinetics of silicate dissolution, carbonation, effects of catalysts, and resulting cementation effects. The computational work will focus on the formulation of new soil constitutive models to simulate concurrent growth of carbonation/cementation and self-weight consolidation of the hydraulic fills. Numerical simulations will investigate the effectiveness of carbonation systems on the hydro-mechanical performance of existing tailings dams, and on designs for new storage facilities.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
