CO₂ mineralization using basic oxygen furnace slag: process optimization by response surface methodology

The basic oxygen furnace steelmaking slag (SL) is employed for CO₂ mineralization. Response surface methodology and the central composite design were employed in determining the optimal condition. The optimization goal in this paper has been set for maximum CO₂ capturing. It was found that the reaction temperature and CO₂ pressure and their combination were significant. A quadratic model was developed for process optimization and statistical experimental designs. The CO₂ capture capacity could reach 126 g CO₂/kg SL at optimal condition. The increased reaction temperature will lead to an obvious decrease of CaCO₃ and increase of MgCO₃. If deployed, this optimized indirect CO₂ mineral sequestration process could permanently capture 252,000 tons of CO₂ per annum based upon current 2 million tons of SL productivity per annum.