Identification of suitable conventional cooling methods for direct aqueous carbonation of blast furnace slags and their mechanism

The iron and steel industries generate large amounts of unavoidable CO2 emissions as well as considerable quantities of slags. More than one-half of the emitted CO2 is produced in blast furnaces during ironmaking, and thus it is meaningful to use blast furnace slags to capture CO2 while addressing the byproducts and flue gas of ironmaking. Mineral carbonation of slags is a promising route to achieve carbon neutrality and effective slag utilization. To exploit slag more effectively and capture CO2 in flue gas, an in-depth investigation into the carbonation of blast furnace slags generated with different cooling methods was conducted. The effects of the solid–liquid ratio and introduced CO2 concentration on carbonation were determined. The CO2 uptake capacity of air-cooled slag (0.04 g-CO2/g) was greater than that of water-quenched slag. The CO2 uptake capacities of the two slags were comparable with those of slags in previous works, indicating the potential of the two slags for CO2 sequestration and utilization even with low-energy input and this fact suggests that this process is feasible.