Effect of Mineral Composition on CO₂ Mineralization and Mechanical Strengthening of Synthetic Tailings

To elucidate the influence of mineral composition on CO₂ mineralization and mechanical reinforcement, three synthetic tailing systems representing felsic, high-calcium silicate, and magnesium-carbonate compositions were prepared using a full-component reconstitution approach. Their carbonation kinetics, phase evolution, pore structure, and mechanical response were systematically investigated. The alkaline buffering duration increased in the order of felsic < high-calcium silicate < magnesium-carbonate types, with plateau durations of approximately 300, 650, and 2000 s, respectively. TG-DTG, XRD, and FTIR analyses collectively indicated composition-dependent formation of carbonate-bearing products, with the magnesium-carbonate type showing the strongest carbonate-related signals. SEM observations further revealed precipitation on particle surfaces and within interparticle regions, suggesting precipitation-induced particle bonding. Nitrogen adsorption-desorption measurements showed pronounced pore-structure reorganization after mineralization; the average pore size converged to approximately 7.5-7.9 nm, whereas the specific surface area decreased in all systems. The failure loads of the felsic and high-calcium silicate types increased by factors of 2.97 and 3.81, respectively. The mineralized magnesium-carbonate type exhibited the highest apparent compressive strength (53.69 kPa). These results demonstrate clear composition-dependent relationships among carbonation, pore evolution, and mechanical response in the synthetic systems. Because the materials were prepared from analytical-grade reagents and no complete carbon balance was established, the results should be regarded as mechanistic model-system evidence rather than quantitative estimates of CO₂ sequestration in natural tailings.