Mineral Carbonation of Mixed Industrial Residues for Enhanced CO2 Sequestration and Environmental Stabilization: The Role of Slag Composition and Industrial Symbiosis

The increase in greenhouse gases (GHGs), particularly carbon dioxide (CO2), represents one of the major environmental challenges of recent decades. Carbon capture, utilization, and storage technologies are essential for deep decarbonization, especially in hard-to-abate sectors. Among these, CO2 mineralization using alkaline industrial wastes is a promising approach, enabling carbon sequestration and waste valorization within a circular economy framework. In this study, the efficiency of mineral carbonation is evaluated as an integrated strategy for permanent CO2 sequestration and stabilization of hazardous components in combustion residues. Fly ash (FA), bottom ash (BA), and slag are investigated due to their strong reactivity toward carbonation. The process promotes the formation of stable carbonate phases, ensuring long-term carbon storage under ambient conditions. Additionally, carbonation enhances the immobilization of heavy metals like Pb and Zn, while contributing to chlorine stabilization through the formation of Friedel's salt. The influence of industrial wastes and by-products on CO2 capture capacity is systematically analyzed, emphasizing the role of BA in improving stabilization mechanisms. Additionally, carbonated FA was valorized as a filler in high-density polyethylene-based composites. The results demonstrate that mineral carbonation represents an effective and sustainable solution for simultaneous CO2 sequestration and waste management, contributing to environmental protection and resource efficiency.