The direct mineralization process using fly ash to storage CO_2 from coal-fired power plant would be a suitable emission reduction technology for China. This paper investigates the effects of process conditions such as chemical and phase composition of fly ash

temperature

gas flow rate

solid to liquid ratio

gas velocity and pressure on the carbonation reaction. The X-ray powder diffraction(XRD) and thermogreviamic analysis(TGA) method were used to study the carbonation reaction mechanism of fly ash with CO_2. The results indicate that

increasing the solid to liquid ratio could effectively improve the CO_2 sequestration capacity but decrease the Ca conversion rate. When the flue gas velocity exceeded a certain value

CO_2 dissolution became the rate-determining step

and the Ca conversion rate reached saturation. The temperature had an important effect on mineralization reaction

studying the process temperature was the key to further improve the effect of mineralization reaction. The maximum CO_2 sequestration capacity of Beijing fly ash reached 0.066 kg CO_2/kg fly ash(?Ca=50.9%) at 60 ℃ with the solid/liquid ratio of 100 g/L and the gas flow rate of 350 mL/min. Based on this technology

a 50 000 t/a CO_2 direct aqueous mineralization device was designed

and the equipment investment and operation cost were estimated. Compared with the foreign carbon dioxide mineralization technology using natural ore raw materials

the reaction conditions of this technology are more mild

and the utilization of fly ash and greenhouse gas emission reduction can be realized at the same time. The technical prospect is broad

which is of great value to the future implementation of carbon neutralization target in China.