XPS and SEM study of calcite bearing rock powders in the case of reactivity measurement with HCl solution

The dissolution of seven natural limestones and calcareous rocks in hydrochloric acid solution was examined to investigate their capability for wet flue gas desulphurisation. All samples were crushed, ground and sieved to a size‐fraction of 150–250 µm. Thereafter they were subjected to a dissolution experiment utilising stepwise titration with hydrochloric acid. The dissolution rates of three calcareous rocks were found to be controlled by reaction kinetics, while the limestones showed mass transfer control. The surface characterisation was implemented before and after dissolution experiments using X‐ray photoelectron spectroscopy and scanning electron microscopy. Additional characterisation was carried out with X‐ray diffraction, X‐ray fluorescence and polarizing microscope. Initial reactivities have been shown to decrease in the order limestone, calcareous rock with high calcium concentration, calcareous rock with low calcium concentration. Coarse grain structure is proposed to decrease the initial reactivity.