Leaching and indirect mineral carbonation performance of coal fly ash-water solution system

The leaching and carbonation performances of indirect mineral carbonation are investigated using coal fly ash (FA) as the raw source and water as the solvent. The reactions were conducted at ambient temperature and pressure with a gas mixture comprised of 15 and 33mol% CO2. The overall CO2 storage and mineral carbonation capacities of FA suspended solution in which alkaline components had been previously leached for 2h (2S33) were 31.06 and 17.36mg CO2/g FA, respectively. The mineral carbonation capacity of FA in 2S33 was 18% of the theoretical value and its mineral carbonation storage capacity ratio was 55.9%. The performance of 2S33 was higher than that of its filtrate because the alkaline components were leached from the suspended FA simultaneously with the mineral carbonation. Submicrometer-sized particles were present in raw FA and their size was reduced by stirring during the leaching, as well as slightly increased, compared to the original raw FA, due to the carbonation. These submicro FA particles strongly affected the performance of the mineral carbonation of the FA-water solution.