Direct Aqueous Mineralization of Industrial Waste for the Production of Carbonated Supplementary Cementitious Materials

In the steelmaking process, electric arc furnace (EAF) is regarded as a green production route, as it essentially uses ferrous scraps instead of virgin raw materials. In addition, the alkaline composition of the slag derived from the EAF production makes it suitable for carbonation treatment, and specifically for the permanent storage of CO2 through the implementation of the mineralization process. Therefore, in this study, EAF slag carbonation is performed in a slurry configuration, at room temperature and ambient pressure, in order to assess the CO2 storage potential under minimized energy consumption conditions. Specifically, the slurry was prepared at a liquid-to-solid ratio of 3; CO2 with a partial pressure of 99.9% was fluxed into the slurry at 25 ℃ under the pressure of 1 bar with a flowrate of 150 L/h, and reaction time of 1 h. Moreover, in order to investigate the reproducibility of the mineralization process, three tests under the same conditions were replicated. The carbonation efficiency was estimated to be around 32%, and the results achieved were compared to previous literature studies. This research confirms that direct aqueous carbonation is a valuable method for inducing mineralization in powdered materials. Future investigations will be aimed at assessing the potential of the carbonated slag to act as supplementary cementitious material by partially substituting clinker binders in cement-based manufacts.