Integrated leaching–carbonation kinetic model on CO2 mineralization of alkaline solid wastes in a high-gravity rotating packed bed

Abstract

Carbon dioxide (CO₂) mineralization by accelerated carbonation using a high-gravity rotating packed bed (HiGee RPB) is a promising process that simultaneously stabilizes industrial alkaline solid wastes and sequestrates CO₂ from flue gas. In this study, the carbonation kinetics depicting the CO₂ mineralization using different alkaline solid wastes in a HiGee RPB were evaluated based on the surface coverage model. The dynamic changes on Ca²⁺ concentration during the carbonation process were successfully fitted and described using the Streeter–Phelps formula. The L/S ratio and high-gravity effect on carbonation conversion (δ_Ca), CO₂ capture capacity (C_cap), and changes of Ca²⁺ concentration (C_Ca²⁺) were discussed. The kinetic model was validated using experimental data obtained by the batch tests. The results indicated that δ_Ca and reaction constants of different alkaline solid wastes were fitted by the surface coverage model with acceptable R² values. The proposed kinetic model was used to elucidate the competition between Ca²⁺ leaching and CaCO₃ precipitation during the carbonation. In addition, the liquid side mass transfer rate enhanced by the high-gravity effect was determined. The enhancement factor was used to identify the relationship between the liquid side mass transfer and chemical reaction.