Regeneration of Sulfated Dolomite and Limestone by Reductive Decomposition

Regeneration properties of sulfated dolomite and limestone samples were investi gated. Natural stones were first fully calcined at 1223 K in a gaseous atmosphere consisting of CO215 vol.% and dry air 85 vol.%; second, sulfation of the calcines was achieved by reacting them with a gaseous mixture consisting of CO215 vol.%, SO20.35 vol.%, and a balance of dry air at 1223 K; last, sulfated calcines were regenerated at 1373 K by a reductive decomposition process. During regeneration a 3:1 volumetric ratio of CO2/CO was maintained in the reducing gaseous atmosphere to minimize CaS formation. It has been found that for the five sulfation generation cycles the reactivity of the limestone and dolomite samples remained at acceptable levels. Since the repeated sulfation-regeneration steps caused an important change on the crystal lattice, as compared to the fresh stones, sorbent reactivity was also changed.