The low-temperature reaction of ferrous sulphide with sulphur dioxide

A kinetic study of a reaction between iron sulphide and sulphur dioxide, 560-700 K, is reported. The measured stoichiometry is summarized: 1.00EeS + 0.13SO(2) --> 0.38Fe(2)S(3) + 0.07Fe(3)O(4) The reaction is strongly deceleratory, alpha-time data are well expressed by the Jander equation with an activation energy 75+/-4 kJ mol(-1). These results are ascribed to a Wagner parabolic oxidation mechanism controlled by Fe3+-ion diffusion across a barrier layer of product Fe2S3. It appears that a porous layer of Fe3O4 small crystals is formed on the outer surfaces, accommodating oxide ions resulting from dissociative adsorption of SO2 with an acceptance of sulphur into the Fe2S3 phase. The rapid reaction of FeS with SO2, particularly during the early stages, identifies this as being of potential interest, worthy of investigation as a route for the removal of this precursor to acid rain from flue gases. The present results indicate that more work would be required to determine whether the reaction can be usefully applied in environmental protection. (C) 1997 Elsevier Science B.V.