Insights into Carbonation Kinetics of Fly Ash from Victorian Lignite for CO2 Sequestration

Abstract

Mineral carbonation of fly ash can both capture and store CO2 permanently in a single process without long-term monitoring. Previous studies indicate that fly ash with high calcium and magnesium contents exhibit promising CO2 fixation capability. However, the reaction mechanisms and kinetics involved in the carbonation reaction of fly ash is still not fully understood. In this study, a typical Victorian brown coal fly ash from Hazelwood power plant was selected to sequestrate CO2 in a direct aqueous carbonation process. Experiments were conducted in a vessel reactor at various temperatures (40, 50, 60, and 70 °C), stirring rates (900, 1050, 1200, and 1350 rpm), and CO2 pressures (3, 4, 5, 6, and 7 bar) to investigate the reaction kinetics and identify the rate-limiting steps of carbonation. The results show that both the carbonation rate and the maximum carbonation efficiency could be improved by optimizing parameters and by the introduction of NaHCO3. Also, the complex effects of the operating parameters...