Combustion of sulphur in spent shale from the Stuart deposit

Abstract

Oil shales contain sulphur in the form of organic sulphur and pyrite. Mineralogical investigation has shown that the reactions of sulphur in oil shale processing are complex, particularly in the combustion of spent shales. Reaction of sulphur dioxide with minerals within the shale matrix leads to partial sulphur dioxide retention at lower combustion temperatures, and slow release at higher temperatures. The release of sulphur dioxide from samples of Stuart spent shale has been examined using a fluidized bed batch technique at 600–900 °C. Sulphur retention is shown to occur at all temperatures, with the lowest release of sulphur dioxide at 750 °C. The release of sulphur is principally reaction rate controlled above 750 °C and diffusion controlled below 700 °C. The data presented can be used to calculate the rate of appearance of sulphur dioxide in the flue gas stream.