STORAGE DURATION EFFECTS ON CO2 UPTAKE CHARACTERISTICS OF CEMENT KILN DUST

Cement kiln dust (CKD), a byproduct of Portland cement manufacturing, is a promising candidate for carbon dioxide (CO2) sequestration via mineral carbonation. However, the effects of long-term storage on the carbonation capacity of CKD remain poorly understood. This study investigates the influence of storage duration on the CO2 uptake characteristics of CKD variants collected from one cement plant at intervals of about two years. The three CKD samples were evaluated using gravimetric and thermogravimetric techniques after undergoing an aqueous carbonation protocol. Despite CKD being an uncontrolled waste stream, experimental results revealed a consistent inverse relationship between storage age and CO2 uptake capacity, suggesting that aging under ambient indoor conditions leads to progressive passive carbonation. These findings not only demonstrate a remarkable material consistency from a single industrial source but also highlight the importance of storage management for maximizing the carbon sequestration potential of CKD. Considering the high carbonation degrees and significant CO2 uptake capacities observed, even in aged samples, this study supports the feasibility of establishing industrial-scale mineral carbonation systems within cement plants, leveraging their own CKD waste for integrated carbon capture and utilization.