Carbonation of basic oxygen furnace slag with metalworking wastewater in a slurry reactor

CO₂ capture by accelerated carbonation of basic oxygen furnace (BOF) slag in a slurry reactor containing metalworking wastewater was investigated in this study. Two types of metalworking wastewater provided by China Steel Corp. (Kaohsiung, Taiwan) were used: cold-rolling wastewater (CRW) and effluent from a metalworking wastewater treatment plant (EW). The effect of operational conditions including the type of metalworking wastewater, reaction time, liquid-to-solid (L/S) ratio, CO₂ flow rate, and slurry volume on the CO₂ fixation process was evaluated. The results indicated that BOF slag in CRW provided the highest degree of carbonation, 89.4%, with a reaction time of 120min, an L/S ratio of 20:1, and a CO₂ flow rate of 1Lmin^-1 at ambient temperature and pressure. In addition, the kinetics of the aqueous carbonation was evaluated using the surface coverage model. This study provided a promising alternative for CO₂ capture from the flue gas in steelmaking process by reusing the metalworking wastewater and steelmaking slag as feedstock, which could reduce the use of water resources as well as the total cost. Compared with other studies in the literature, this study showed a higher carbonation conversion with less consumption of energy and resources.