Carbon dioxide sequestration by accelerated carbonation of Waelz slag

This work reports the results of a study on accelerated carbonation of Waelz slag, with a focus on the effects of process conditions on CO2 uptake and conversion yields. Carbonation experiments were performed at different operating conditions by using different water contents (L/S = 0, 0.2, 0.4 and 1 l/kg), CO2 pressure (1, 3, 5, 10 and 20 bar) and process duration (up to 240 h). The operating parameters significantly affected the extent of CO2 sequestration and the evolution over time of the process. CO2 uptakes benefited from increasing singularly either L/S or CO2 pressure, with a more relevant effect observed for L/S as compared to CO2 pressure. The maximum CO2 uptake of 6.48±1.00% was achieved at a L/S=1 and CO2 pressure P=20 bar, while the minimum uptake of 1.47±0.56% was achieved for L/S=0 and P=1 bar. The corresponding degrees of carbonation were 18.32 and 4.16%, respectively, indicating that the potential for CO2 sequestration from Waelz slag was only partially exploited even when the optimal conditions were adopted.