Capacity of Ca-based slags for carbon capture

Efficiency in reutilization of Ca-based waste for carbon capture has gained high interest. Besides, the CO2 capture mechanism will be influenced by several operating parameters. Observation of carbonation by Ca-based slags (desulfurization slag/De-S, electric arc furnace/EAF slag, and bottom ash/BA) in this study indicated that De-S had the highest Ca(OH)2 content (73%) and largest surface area which led to the best slag utilization. This slag was further applied in the test under various operating conditions including temperature, space velocity, and the content of gas impurity (H2O and SO2). Higher temperature and lower space velocity promoted efficient carbonation. De-S endured the presence of ≤5% water vapor content in the simulated gas. Higher SO2 content in the simulated gas initiated the formation of CaSO4 and declined the CO2 capture capacity. Discussion in this study was complemented by the characterization of slags before and after carbonation process along with reaction kinetics analysis. [Display omitted] •Desulfurization slag had high Ca(OH)2 and surface area for efficient CO2 capture.•Water vapor below 5% supported carbonation but exceeding content led to a decline.•SO2 reduced the carbonation reaction due to blocking from CaSO4.•Deactivation Type I was well fitted the result with Ea of 352.2 kJ/mol.