Insight into the Direct Carbonation Process of Ca2SiO4 Based on ReaxFF MD Simulation and Experiments

Ca2SiO4 is the primary carbonation-reactive mineral in steel slag, and demonstrates significant carbon sequestration potential, yet its microscopic reaction processes remain unclear. This study investigated the carbonation behavior of Ca2SiO4 using ReaxFF MD simulations. The results indicated that as CO2 concentration increased, the capture rate of Ca2SiO4 decreased, and the molecular structure of the resulting CaCO3 varied in oxygen origin. At room temperature, the carbonation rate of Ca2SiO4 gradually decreased over time until it reached equilibrium. Increasing the temperature could reactivate the carbonation, but the rate would still decline until it reached equilibrium again. Higher temperatures could accelerate the formation of the intermediate C2O52- and internal CO32- diffusion, thereby boosting the carbonation and increasing CO2 adsorption. This study investigated the carbonation of Ca2SiO4 at the atomic level, aiming to link microscopic molecular processes with macroscopic experimental phenomena, thereby providing a theoretical foundation for enhancing the carbonation efficiency of steel slag.