Carbon sequestration potential of cement kiln dust: Mechanisms, methodologies, and applications

Cement kiln dust (CKD), a byproduct of cement production, holds significant potential as a carbon sink. This review comprehensively examines the physical, chemical, and mineralogical characteristics of CKD, highlighting its suitability for carbon dioxide (CO2) capture and sequestration. With a high calcium oxide content of 37-77% and notably high alkalinity, CKD undergoes intricate carbonation reactions, resulting in the formation of stable carbonates. The overview delves into various carbonation pathways, providing a robust framework for assessing CO2 uptake in CKD. Metrics such as carbonation rate and degree prove crucial in quantifying CO2 uptake, with moisture availability emerging as a pivotal factor. The reported carbonation rate ranges from a CO2 uptake of 1.5%-27% by mass of dry CKD. Carbonation degrees above 60% have been widely reported, while some researchers reportedly achieved higher degrees, including full attainment of theoretical CO2 uptake. Beyond environmental impact reduction, carbonated CKD shows promise in construction materials and toxic component immobilization. Research priorities were identified, emphasizing scalable carbonation techniques and diverse applications for carbonated CKD. In conclusion, CKD offers a valuable opportunity to enhance the sustainability of cement production. Further research and development are essential to fully exploit CKD's potential as a carbon sink, driving the industry towards greater environmental sustainability.