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Publisher Summary The increasing concentration of “greenhouse gases,” including carbon dioxide (CO2), methane (CH4), and water vapor in the earth's atmosphere has led to calls for reduction of CO2 emissions from fossil-fuel-fired power plants. Several potential methods to sequester CO2 are currently under investigation, including terrestrial and ocean sequestration, geological sequestration, and mineral carbonation. Fossil-fuel-fired power plants contribute approximately one third of the total human caused emissions of carbon dioxide. Increased efficiency of these power plants will have a large impact on carbon dioxide emissions, but additional measures will be needed to slow or stop the projected increase in the concentration of atmospheric carbon dioxide. By accelerating the naturally occurring carbonation of magnesium silicate minerals, it is possible to sequester carbon dioxide in the geologically stable mineral magnesite (MgCO3). The carbonation of two classes of magnesium silicate minerals, olivine and serpentine, was investigated in an aqueous process. The slow natural geologic process that converts both of these minerals to magnesite can be accelerated by increasing the surface area, increasing the activity of carbon dioxide in the solution, introducing imperfections into the crystal lattice by high energy attrition grinding and, in the case of serpentine, by thermally activating the mineral by removing the chemically bound water. The effect of temperature is complex because it affects both the solubility of carbon dioxide and the rate of mineral dissolution in opposing fashions. This chapter elucidates the interaction of these variables and use kinetic studies to propose a process for the sequestration of the carbon dioxide. |
