Optimised steel slag carbonation for enhanced CO2 sequestration: A comprehensive study using response surface methodology (RSM)

This study utilises response surface methodology (RSM) to optimise the conditions under which CO2 sequestration occurs during the pioneering use of steel slag in a mineral carbonation process. Crucial factors such as time, reaction temperature, pressure conditions and the liquid/solid ratio are systematically varied and analysed to determine if CO2 sequestration is efficient.
The results show that the amount of carbon captured was directly impacted by the relationship between time and temperature. For instance, when these variables increased from 20 °C to 90 °C and one day to four days respectively, carbon sequestration in ladle slag increased from 101.23 kg to 149.32 kg of CO2 per tonne, a rise of approximately 48 %. Moreover, carbon sequestration was also enhanced when pressure and the liquid/solid ratio increased, although this effect declined once a certain level was reached. From the application of RSM for 120.46 kg of CO2 per tonne of steel slag, the ideal reaction conditions were predicted to be 60.83 °C, a reaction time of one day, 15.63 bar pressure and a 90/30 liquid/solid ratio. These predictions were validated through experimentation, which generated a result of 118.03 kg of CO2 per tonne of steel slag with a relative error of 2.04 %.