CO2 Sequestration: Temperature and Gas Compositional Effects on the Kinetics of Mineralogical Reactions

Abstract

Abstract It may be possible to lower costs of Carbon Capture and Sequestration by keeping constituents such as sulfur dioxide (SO2) in the flue gas stream. The reactive behavior of pure CO2 and CO2 + SO2 mixtures within a geologically realistic environment was examined. The experimental apparatus consisted of a series of four high-pressure reactors operated at different conditions and with different feed gas compositions to observe changes in both the rock and water compositions. The rock consisted of equal proportions of quartz, calcite, andesine, dolomite, chlorite and magnesite (constituents in arkose or dirty sand stone). The brine was prepared from laboratory grade sodium chloride and by varying the amount of magnesium concentration in the brine. Several long-term batch experiments with pure CO2 were carried out at different temperatures. Each mineral in the mixture showed evidence of participating in the geo-chemical reactions. Layers of calcite were seen growing on the surface of the arkose. Analcime deposits were omnipresent, either occurring as large connected aggregates or as deposits on the surfaces of other minerals (Quartz). Ankerite and calcite depositions were observed as amorphous masses intergrown with the feed. The CO2 + SO2 mixture experiments showed growth of euhedral anhydrite crystals and pronounced dissolution patterns over the examined surfaces. The growth of these new phases would lead to significant changes in the petrophysical properties of the rock. The trends in ionic concentration changes in the aqueous phase complemented the changes in the rock chemistry. The rates of these reactions were computed by measuring the changes in the compositions of the initial and the final samples. The rates of these reactions were computed by computing the changes in the compositions of the initial and the final rock samples (both individual and mixture) provided by the XRD analyses and were observed to be lower than expected.