EMISSIONS OF SO2 DURING BATCH FLUIDIZED-BED COMBUSTION OF RUNDLE RETORTED SHALE

Results are presented showing the existence of some mineral reactions affecting the emission of SO2 during the combustion of Rundle retorted shale in a batch fluidized-bed combustor. Evolution of SO2, CO2 and C O was observed while the sample was quickly heated in N2 to 820-degree s-C. SO2 emission (<5% of the total S in the sample) was the result of a reaction of pyrite with a high concentration of steam produced from the free moisture and clay-bound water. One-third of the CO, release was from the decomposition of calcite. Pyrolysis of char and reduction of iron oxides by carbon produced the rest of the CO2 and CO. The com bustion following the pyrolysis was characterized by a high molar CO/C O2 ratio and a long delay in SO2 emission. Combustion of char consumed initially all available oxygen in the feed gas and therefore delayed the combustion of pyrite/pyrrhotites.