Mineral carbonation of CO₂ with utilization of coal gasification slags based on chemical looping

Abstract

Aiming to utilize CO2 and solid waste form coal chemical industry synchronously, we proposed a novel process which integrated CO2 mineral carbonation and utilization of gasification slags based on chemical looping. With NH4Cl as the loop chemical, which generated HCl and NH3 through pyrolysis, the aluminum, calcium, and so forth were extracted by HCl from the coal slag, and CO2 was mineralized by calcium and NH3. NH4Cl was recovered after mineralization, and chemical looping was closed. A pilot setup with a capacity of 1‐kg CO2/h was conducted to demonstrate the feasibility of the chemical looping process. An airlift reactor was employed for mineral carbonation reaction, and conditions for extraction and mineral carbonation were optimized. The process presented the CO2 conversion of more than 90% with a calcium overall utilization ratio of 74.8%. The CO2 sequestration potential of the gasification slag is 121‐g CO2/kg slag, which is higher than that of steel slag and red mud. Calcium carbonate with the particle size of 1–10 μm can be obtained during the mineral carbonation. Simultaneously, the process extracted and enriched 62.3% of aluminum in the slag and enabled the deep utilization of the slag.