Multicyclic study on the carbonation of CaO using different limestones

Abstract

Different samples of limestones, with small differences in their stoichiometry, have been studied comparatively. The carbonation reaction has been studied for a large area of isothermal temperatures. The conditions for the multicyclic experiments of calcination/carbonation were: isothermal temperature 670°C, heating time 60 min and carrier gas CO₂. The final carbonation conversion depends mainly on the isothermal temperature of the carbonation reaction and the heating time. The final temperature of the calcination reaction depends on the percentage of CaO that it has not been conversed to CaCO₃ in the repeated carbonation experiments. The quantity of CaO that has not been carbonated, in the same sample, affects the values of the coefficients of the kinetic model that fit the calcination reaction. In the multicyclic experiments the carbonation conversion for two of the four studied samples, was high enough in comparison to other samples of calcite. At sample A the reduction of the carbonation conversion during the first five cycles is less than it is at other samples from the literature. Under the above experimental conditions — isothermal temperature and heating time — specific samples consisted mainly of calcite can absorb larger quantities of CO₂ than samples consisted mainly of dolomite.