Inaccessible pore volume formation during sulfation of calcined limestones

A mathematical model for transport, reaction and structure evolution in gas‐solid reactions with solid product is used to analyze a set of experimental data for the sulfation of calcines derived from three stones of high (>95%) calcium carbonate content. The analysis of the experimental data places emphasis on the formation of inaccessible pore space and its effects on the efficiency of calcined limestones as sorbents for SO2 removal. Our results show that the ultimate capacity of calcined limestones for SO2 uptake is influenced strongly by the formation of inaccessible pore space, which in turn is determined by their pore‐size distribution and the connectivity (degree of interaction) of the pores. For the three specimens used in our study, the ultimate conversion (measured experimentally) increased and the inaccessible pore space formed during pore closure (predicted by the mathematical model) decreased with decreasing grain size in the rock precursors, indicating that the morphological texture of the precursors plays a major role in determining the topological features of the pore structure of the resulting calcines.