✍ Scribed by D. Carl Anderson; Peter Anderson; Andrew K. Galwey
No coin nor oath required. For personal study only.
The significant changes of surface texture in CaCO, crystallites due to reaction in an equimolar SO,-O2 mixture were examined by scanning electron microscopy. Surface modifications were extensive above 870 K, which is close to the temperature of CaCO, dissociation and of CaSO, oxidation. It appears that both rate processes participate in the conversion of calcite to CaSO, by reaction with SO2 under oxidizing conditions. The results confirm the production of sulfate above 870 K, but this generation of product across the surfaces represents a barrier to gas-solid contact that prevents complete reaction of the CaCO, particles. The observations show that potassium ions enhance CaSO, formation, probably by promoting fusion of the barrier layer, and that rapid heating does not disrupt calcite crystals sufficiently to increase the reactant surface area. The product barrier layer is identified as controlling both rate and extent of the reaction of calcite in desulfurization processes.
📜 SIMILAR VOLUMES
The combustion of sulfur-containing coal particles on a calcium carbonate crystal results in retexturing of a neighbouring CaC03 (100) face. The structural modifications developed at the CaCO, crystal surface show similarities to those found after reaction of calcite in SO, and O2 (air). It is concl