Study of oxidative desulphurization process of coal with different metamorphism degrees

The oxidative desulphurization process of coal with different metamorphism degrees treated by an air-steam mixture has been studied. It has been shown that the pyrite present in black coal and anthracite is oxidized with the sulphur dioxide formation, and the process chemical mechanism does not depend on the quality of organic matter. The medium-metamorphized coal, capable of turning into a plastic state and cake in the range of investigated temperatures (350~450 ℃), is desulphurized with the greatest difficulty. The chemical mechanism dealing with the transformations of pyritic sulphur present in brown coal differs from similar processes taking place in black coal and anthracite, because FeS₂ is converted with hydrogen sulphide formation at desulphurization.