Abstract
Using a thermobalance, a hematite pellet was reacted with H2-CO mixtures at 9731073K to produce an iron carbide pellet. H2S of low pressures unable to form FeS was added to the mixtures. First, reduction of iron oxides proceeded and then carbidization of metallic iron occurred. Small amounts of H2S in gas led to iron carbides (Fe3C, Orthorhombic) with complete conversion rather than free carbon or metallic iron as final products. In later stage of carbidization, higher iron carbide (Fe2.5C, Monoclinic) appeared partially in lower temperatures. The conditions of higher temperature and low sulfur pressure provided high quality iron carbides having nearly less than 0.03 mass% S. The tests without H2S provided lower iron carbide contents with much free carbon or metallic iron. Carbidization rates of a reduced iron pellet were analysed by an unreacted core model to investigate this process. The carbidization proceeded more rapidly in lower temperatures.
