(672c) Utilization of Alkaline Wastes from Petrochemical Industry for CO2 Fixation and Supplementary Cementitious Material Production

In this study, an integrated approach to establishing a waste-to-resource supply chain in the petrochemical industry was developed for CO₂ fixation, wastewater neutralization and product utilization using a high-gravity carbonation (HiGCarb) process, i.e., rotating packed bed (RPB).  According to our previous experience, a high CO₂ capture efficiency (i.e., >98%) can be achieved by utilizing basic oxygen furnace slag and cold-rolling wastewater via the HiGCarb process with a relatively short reaction time at ambient temperature and pressure.  Therefore, several alkaline wastes, such as byproduct lime, were gathered for performance evaluation operated under various levels of reaction temperature, rotation speed, and liquid-to-solid (L/S) ratio.  The alkaline wastes were found to be successfully carbonated with CO₂ in the high-gravity carbonation process, where calcite (CaCO₃) was identified as the main product.  In addition, the results indicated that the rates of metal ion leaching from the alkaline solid wastes can be prohibited by the high-gravity carbonation process.  Moreover, blended cements containing 5%, 10% and 20% replacements of ordinary Portland cement (OPC) with carbonated solid wastes were tested for compressive strength development and autoclave soundness.  The mortars were casted into 50 mm × 50 mm × 50 mm molds, and then tested at 3, 7, and 28 days according to ATSM C109.  Since the reacted product (e.g., carbonated solid wastes) can be used as supplementary cementitious materials, CO₂ emissions from the cement industry can be avoided if a green waste-to-resource supply chain between the petrochemical and cement industries is established.  It was concluded that an integrated approach to the proper treatment of alkaline wastes that permanently fixes CO₂ from the petrochemical industry while producing valuable supplementary cementitious materials for the cement industry can be achieved via the HiGCarb process.