| dc.description.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 circular economy perspective. In many cases, the amount of waste is so high that it cannot be handled and is freely piled in nature. Hence, 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 lab-scale 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 and after a comprehensive systematic literature review, four different mineralization processes applying different chemicals and using different CaO-rich wastes, all with a relatively high performance documented from laboratory experiments, were chosen. These processes were scaled up to the industrial size of a pilot plant with capacity of 400 tons of CO2 to be captured in a year and outlined with the required process equipment. Based on published lab results, mass and energy balances of the up-scaled processes were then performed, and key performance indicators of the processes in three different countries were calculated using an in-house-made process simulation tool. Furthermore, a comparative technical, economic, and environmental analysis was conducted for all processes.
The results indicate that process 2 (using recycled concrete fines as waste and NH4Cl as reagent) has the highest amount of CO2 captured per mass of industrial waste (0.33 kg/kg) and consumes the least amount of reagent per mass of captured CO2 with 0.5 kg/kg. Meanwhile, process 1 (using converter slag as waste and NH4Cl as reagent) has the least energy consumption per mass of captured CO2 with 1.48 kWh/kg. Process 3 is characterized by blast furnace slag as waste and HCl as reagent. All processes are economically feasible in each scenario except process 4 (using converter slag as waste and CH3COOH as reagent). This means that CO2 sequestration via mineralization using CaO-rich industrial wastes is a promising solution not only in terms of circularity and emitted CO2 reduction, but also as an attractive business case. | |
