Evaluation of factors affecting mineral carbonation of CO2 using coal fly ash in aqueous solutions under ambient conditions

This study examined the factors affecting mineral carbonation to sequester CO2 using coal fly ash (CFA) in aqueous solutions under ambient temperature and pressure conditions. Serial extraction and carbonation tests were conducted on CFA obtained from a coal-fired power plant as the following conditions were varied: solid dosage, CaO content, CO2 flow rate, and solvent type. The solid dosage, CaO content, and solvent type affected the Ca extraction efficiency, which was well correlated with the carbonation efficiency. In addition, at a given Ca extraction efficiency, the CO2 flow rate and the solvent type affected the rate and extent of CFA carbonation. Based on the study results, the CO2 sequestration capacity of CFA under ambient temperature and pressure conditions was approximately 0.008 kg of CO2 per 1 kg of CFA at the experimental test conditions (CaO content: 7 wt.%, solid dosage: 100 g/L, CO2 flow rate: 2 mL/min, and solvent: DI water).

► A conceptual in situ mineral carbonation method using coal fly ash is proposed.
► Coal fly ash can be used as a raw material for sequestering CO2 by mineralization.
► Ca extraction is a primary step affecting the overall mineral carbonation process.
► CO2 delivery rate affects the rate and extent of the mineral carbonation process.
► More research is required to enhance the Ca extraction efficiency without energy inputs.