The Use of Limestones Built of Carbonate Phases with Increased Mg Content in Processes of Flue Gas Desulfurization

The purpose of this article was to present the theory of the possibility of using limestone sorbents containing carbonate minerals with increased Mg content in processes of flue gas desulfurization in power stations. Data obtained as a result of the conducted research show that the analyzed Triassic (Muschelkalk) limestones of the south-west part of Poland are built of the following carbonate minerals: low magnesium calcite, high magnesium calcite, dolomite and huntite. These carbonate minerals are characterized by various magnesium contents. The increased content of magnesium in the sorbent has a positive effect on the technological process of flue gas desulfurization using the dry method, especially in the case of desulfurization with the application of Fluidized Bed Reactors. The positive influence of magnesium’s presence in sorbent in the desulfurization process is connected with the decarbonization of carbonate phases with magnesium at temperatures similar to the dolomite decarbonization temperatures, which are, thus, lower than typical for low magnesium calcite. The process would be easier because the structure of a solid solution containing magnesium ions, with a smaller ion radius to calcium ions, is unstable and the decomposition of these phases runs easier and faster. Therefore, the desulfurization process starts earlier and is more effective.