| The containment of carbon dioxide involves several steps including CO 2 separation, transportation, and sequestration. This study addresses the sequestration step, employing mineral carbonation. Specifically, mechanistic and kinetic characteristics of aqueous carbonation of Mg-bearing minerals, which underline the methodology development for mineral sequestration of CO 2, were explored.; Mineral carbonation is achieved through mimicry of natural inorganic chemical transformation of CO2, such as the weathering of rocks and dissolution of CO2 in seawater/saline waters to form bicarbonates. This sequestration process presents a safe and permanent method of CO 2 containment that is based on chemical fixation of CO2 in the form of geologically and thermodynamically stable mineral carbonates. The total accessible amounts of the Mg-bearing minerals were estimated to significantly exceed the worldwide coal reserves.; Screening of mineral samples for their application in the CO2 mineral sequestration scheme identified both olivine and serpentine to be the viable candidates. According to the experimental results, the chemically enhanced aqueous carbonation of serpentine showed promising results. Next, the effect of the physical activation on the dissolution of serpentine was investigated and a pH swing scheme was developed to improve the overall conversion of the CO2 mineral sequestration process.; Using the proposed pH swing scheme, the overall conversion of the mineral carbonation was radically improved. By controlling the pH of the system, three solid products were generated: SiO2-rich solids, iron oxide and MgCO3·3H2O. Since the iron oxide and magnesium carbonate produced were highly pure, these value-added products could eventually reduce the overall cost of the carbon sequestration process. In addition, it was found that the Mg-rich solution prepared during the pH swing process was also effective at removing SO2 from flue gas.; Finally, in order to completely evaluate the proposed mineral carbonation process for the CO2 sequestration, a life-cycle assessment (LCA) was performed using an appropriate system boundary. According to the LCA results, a lower reaction temperature is desired, since most of the energy requirement came from heating the reactor. In addition, it was important to identify and ensure the use of three valuable byproducts in order to carry out the proposed carbon sequestration process as a net consumer of carbon dioxide. (Abstract shortened by UMI.)... |
