SULFIDATION OF LIMESTONE-DERIVED CALCINES

The sulfidation of calcines derived from three limestone precursors of high calcium carbonate content (>95%) was investigated by carrying out reactivity evolution experiments in a thermogravimetric analysis system. Calcination experiments were conducted at 750 and 850-degrees-C, and the resulting calcines were reacted at 750 and 650-degrees-C. The overall rate of sulfidation was found to be influenced strongly by the particle size (for particles in the size range of 53-350 mum) but rather weakly by the sulfidation temperature. The obtained experimental data were analyzed by using a mathematical model for gas-solid reactions based on a pore network description of the pore structure. The comparison of model and experiment showed that most differences in the behavior of limestone-derived sorbents during sulfidation originate from differences in the connectivity (degree of interaction) of their pores.