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Mineral carbonation is a promising CO2sequestration strategy that can utilize industrial wastes to convert CO2into high-value CaCO3. This review summarizes the advancements in CO2mineralization using typical industrial wastes to prepare ultrafine CaCO3. This work surveys the mechanisms of CO2mineralization using these wastes and its capacities to synthesize CaCO3, evaluates the effects of carbonation pathways and operating parameters on the preparation of CaCO3, analyzes the current industrial application status and economics of this technology. Due to the large amount of impurities in solid wastes, the purity of CaCO3prepared by indirect methods is greater than that prepared by direct methods. Crystalline CaCO3includes three polymorphs. The polymorph of CaCO3synthesized by carbonation process is determined the combined effects of various factors. These parameters essentially impact the nucleation and growth of CaCO3by altering the CO2supersaturation in the reaction system and the surface energy of CaCO3grains. Increasing the initial pH of the solution and the CO2flow rate favors the formation of vaterite, but calcite is formed under excessively high pH. Vaterite formation is favored at lower temperatures and residence time. With increased temperature and prolonged residence time, it passes through aragonite metastable phase and eventually transforms into calcite. Moreover, polymorph modifiers can decrease the surface energy of CaCO3grains, facilitating the synthesis of vaterite. However, the large-scale application of this technology still faces many problems, including high costs, high energy consumption, low calcium leaching rate, low carbonation efficiency, and low product yield. Therefore, it is necessary to investigate ways to accelerate carbonation, optimize operating parameters, develop cost-effective agents, and understand the kinetics of CaCO3nucleation and crystallization to obtain products with specific crystal forms. Furthermore, more studies on life cycle assessment (LCA) should be conducted to fully confirm the feasibility of the developed technologies.

Under the dual-carbon target, CO2mineralization through solid wastes presents a mutually beneficial approach for permanent carbon emission reduction at a low material cost, while also enabling the resource utilization of these wastes. However, despite its potential, a comprehensive understanding about the effect of industrial solid waste properties and operating parameters on the carbonation process, and the mechanism of direct aqueous carbonation is still lacking. A series of experiments were conducted to compare the carbonation performance of fly ash, steel slag, and carbide slag. Subsequently, CO2mineralization by carbide slag was systematically studied under various operating parameters due to its high CO2sequestration capacity. Results showed the reactivity of CaO and Ca(OH)2was higher than that of CaO·SiO2and 2CaO·SiO2. Carbide slag demonstrated a sequestration capacity of 610.8 g CO2/kg and carbonation efficiency ζCaof 62.04% under the conditions of 65 °C, 1.5 MPa initial CO2pressure, 15 mL/g liquid-to-solid ratio, and 200 r/min stirring speed. Moreover, the formation of carbonates was confirmed through XRD, SEM-EDS, TG, and FTIR. A mechanism analysis revealed that initially, the rate of the carbonation process was primarily controlled by the mass transfer of CO2in the gas–liquid interface. However, the rate-determining step gradually shifted to the mass transfer of Ca2+in the solid–liquid interface as the reaction time increased. This study lays the foundation for the large-scale implementation of CO2sequestration through carbide slag carbonation.