CompuServe Messages

Elizabeth – I work in a plant that manufactures sulfuric acid and elemental sulfur. It is the second process that brings to bear on your question. In the Claus process of sub-stoichiometric combustion of H2S (hydrogen sulfide), 1/3 of the H2S is oxidized to S02 which reacts with the remaining H2S to form S + H2O. Most of the process piping is carbon steel. In the strongly reducing conditions, with significant sulfur compounds present, a pyrophoric iron sulfide does form. The steel becomes sulfided, scales off, and deposits in the Claus catalyst beds. Whenever we shut the sulfur plant down for catalyst change, we have to slowly increase the O2 concentration in the process gas to slightly above 0.5% to promote controlled oxidation of the FeS. If this weren't done, a significant fire would begin once the catalyst was exposed to the atmosphere. Given the multiple valences of both iron and sulfur, I couldn't hazard a guess as to what the actual formula is for the pyrophoric variety. Hope this helps! and thanks for the Moab tips….unfortunately I didn't read them until we returned (today). sure is a cool place for being so d*mned hot ( 111 on Saturday ) Michael