CO 2 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 CO 2 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 (ζ Ca [%]) 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 CO 2 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 CO 2 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.