Integrated high-gravity process for HCl removal and CO2 capture using carbide slag slurry in a rotor-stator reactor: Experimental and modeling studies

Abstract

The treatment of flue gas containing HCl and CO2 has garnered significant attention. This study proposes an integrated high-gravity process based on a rotor-stator reactor (RSR) for HCl removal and CO2 capture through mineralization using carbide slag slurry (CSS), an industrial waste. Experimental and modeling studies were conducted to investigate the absorption performance and mass-transfer mechanism. Considering the properties of CSS, Ca(OH)2 slurry was used to simulate CSS for HCl and CO2 absorption in the RSR. The influences of solid content, rotational speed, gas flow rate, and liquid flow rate were investigated, resulting in HCl and CO2 absorption efficiencies of 87.3%–98.9% and 33.8%–65.7%, respectively. Two mechanistic mass-transfer models were established based on surface renewal theory and penetration theory, respectively, to depict the process. The predicted values aligned well with the experimental results, with deviations generally less than 25%. The study further explored the absorption of HCl and CO2 using an actual CSS operated in recycle in the RSR and investigated the characteristics of the solids in fresh and carbonated CSS using XRD, TGA, and SEM. The results indicated that the actual CSS had excellent absorption performance, generally consistent with Ca(OH)2 slurry, and that Ca(OH)2 in CSS was almost completely converted to CaCO3 (calcite).