Optimised steel slag carbonation for enhanced CO₂ sequestration: A comprehensive study using response surface...

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 %.