CO2 capture and mineralization using carbide slag doped fly ash

A novel direct gas–solid mineral carbonation process using carbide slag doped fly ash to capture and mineralize CO2 from flue gas was developed to overcome the barriers of long reaction time and large reactor size from aqueous processes. A laboratory‐scale fixed bed reactor with a thermogravimetric analyser and a pilot‐scale circulating entrained‐flow bed (CEB) rector system were constructed to investigate the intensification method and reaction parameters. The carbonation efficiency (ζCa [%]) was improved four times by carbide slag doped fly ash in a semi‐dry atmosphere; thus, the active calcium hydroxide from carbide slag and fly ash can react with CO2 in a thin liquid film through an ionic reaction route. The key reaction parameters, such as temperature, steam addition and water injection, were studied to promote Ca(OH)2 formation and to facilitate CO2 diffusion. As a result of the pilot‐scale experiment, carbonation efficiency achieved a maximum value of 55% with 15% steam addition in the feed and 6 kg h–1 water injection into CEB at 550 °C. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.