Process Intensification of Steel Slag Carbonation via a Rotating Packed Bed: Reaction Kinetics and Mass Transfer

Abstract

Abstract The carbonation of alkaline wastes for CO 2 capture was mainly controlled by the CO 2 dissolution, i.e., mass-transfer controlled reaction, from the theoretical considerations. Several approaches to enhancing the CO 2 dissolution rate were proposed and investigated in the literature. For instance, it was proven that the rate of carbonation reaction for alkaline waste was effectively increase mass transfer rate if a rotating packed bed (RPB), so-called “high-gravity” or “HIGEE” process, was utilized. In this study, the experimental data were utilized to develop the carbonation model in an RPB for carbonation of various types of alkaline wastes such as basic oxygen furnace slag (BOFS) and cold-rolling mill wastewater (CRW). The effect of different operating parameters including operation modulus and rotating speed on CO 2 removal efficiency was evaluated. In addition, the overall volumetric gas-phase mass transfer coefficients (K G a) of BOFS/CRW carbonation in the RPB were calculated. Furthermore, according to the SEM observations, the alkaline wastes were found to be successfully carbonated with CO 2 in an RPB, where calcite (CaCO 3 ) was identified as the main product. It was thus concluded that accelerated carbonation of alkaline wastes using an RPB is an effective and efficient method for CO 2 capture due to its higher mass transfer rate and carbonation conversion.