Morphology of iron reduced from wustite with H2-H2O-H2S mixtures.

The reduction of pure wustite plates with H2–H2O–H2S mixtures has shown that the overall reaction rates are varied over several orders of magnitude in response to the product morphology, which are Type A (porous iron), Type B (porous wustite covered with dense iron), and Type C (dense wustite covered with dense iron), depending on its temperature, the oxygen and sulphur potentials in reducing gas, and cation defect concentration in wustite.The reduction of wustite doped by traces of sulphur and the reduction experiment of changing from initial gas composition into different one were also conducted on the emphasis of the action of sulphur.The results indicated together with the result of Auger electron spectroscopy that sulphur segregates more strongly on the surface of metallic iron rather than wustite and at the same time into the interface between them during reduction.On the basis of these knowledge, the iron morphologies were interpreted by a mechanism composed of several experimental conditions and factors affecting the nucleation and growth of iron.