Recent advances in CO2 mineralization by alkaline industrial solid waste: Mechanisms, applications and perspectives

Abstract

The rapid development of industry has led to a continuous increase in alkaline industrial solid waste, making its sustainable resource utilization a global challenge. Using alkaline industrial solid waste for CO₂ mineralization helps to sequester CO₂ and achieve alkaline industrial waste utilization. This paper provides a comprehensive overview of the CO₂ mineralization mechanism and application of four typical alkaline industrial solid wastes, including steel slag (SS), fly ash (FA), red mud (RA), and desulfurization gypsum (DG). Alkaline industrial solid waste contains CaO, MgO capable of reacting with CO₂ to form stable carbonate-like compounds. The CO₂ sequestration capacities of SS, RM, FA, and DG are 52–310 g/kg SS, 5–175 g/kg RM, 11–210 g/kg FA, and 53–128 g/kg DG, respectively, depending on its composition and mineralization pathway. The technical applications can be divided into laboratory applications and pilot applications. The former reveals the CO₂ mineralization mechanisms, facilitating the subsequent pilot applications. The mineralized products are primarily utilized as building materials. In addition, the process of CO₂ mineralization by alkaline industrial solid waste faces challenges such as reaction kinetics limitations, low calcium carbonate conversion rates, and harsh reaction conditions. Finally, the mechanisms of enforced mineralization and co-mineralization of multiple alkaline solid wastes, as well as the use of machine learning (ML) to improve the efficiency of life cycle assessment (LCA), are proposed as future research directions. This paper is beneficial for guiding CO₂ sequestration and alkaline industrial waste recycling.