Modelling and Simulation of CO2 Capture through Aqueous Indirect Mineralization using CaO-containing By-products

Abstract

The amount of CO2 in the atmosphere is continuously increasing, resulting in climate change and global warming. Industrial processes contribute a substantial share in the amount of CO2 released to the atmosphere. On the other hand, different types of wastes and by-products are being produced by different industries which are deemed pollutants and require energy and capital to be safely managed through a circular economy perspective. A solution to simultaneously tackle both the CO2 emission and waste pollution problems would be of high value. CO2 sequestration by mineralization of CaO-rich industrial wastes is one potential solution. In such a process, CO2 reacts with the CaO in the waste and CaCO3 is produced. This product is thermodynamically stable and has multiple uses. Many studies in the literature have reported use of various CaO-rich wastes to capture CO2, but they are mostly based on labscale experiments, and mostly the focus is on the chemistry of the suggested processes. Hence, there is a need to study the technical and economic feasibility of up-scaled industrial versions of such processes. In this study, four different aqueous indirect mineralization processes applying different chemicals, all with a relatively high performance documented from laboratory experiments, are scaled up to industrial size with a CO2 capturing capacity of 400 t/y using an in-house-made process simulation tool. Furthermore, an economic analysis and environmental assessment are conducted for all processes, and the results are compared. Finally, parameters impacting the techno-economic feasibility of each process are evaluated through a sensitivity study. The results indicate that the potential of capturing CO2 and producing CaCO3 can be as high as 530 kg and 1200 kg per ton of the waste while the yearly energy consumption can be as low as 0.7 kWh per kilogram of captured CO2. The aqueous indirect mineralization of CO2 can be profitable and the emitted CO2 by the process can be so low as 6% of the captured amount.