Development of Efficient Iron Carbide Production Process utiizing directly Natural Gas

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Recently, the steel scrap recycling process in steelmaking is getting more important for mitigation of global environment, resources, and energy problems. This process needs partly pure alternative iron sources such as reduced iron or iron carbide (mainly Fe3C) due to dilution of impurities in steel scrap. Particularly, iron carbide is being noticed worldwide with great interests, because it provides many benefits such as containing much carbon as heat sources, realizing low nitrogen level in steel and so on.On these circumstances, we have performed laboratory experiments to produce iron carbides from iron ores in a ceramic boat with H_2-CO or H_2佑H_4 mixtures and recognized the possibility of an excellent process for the efficient production of stable iron carbides over a wide temperature range such as 550-1000℃. This process is operated under low sulfur pressures to prevent the formation of FeS and is more superior than conventional methods. Therefore, these new techniques to produce … More stable iron carbides were patented to several related foreign countries.In this scientific research (B), using a thermobalance, industrial hematite pellets were reacted with pressurized H_2-CH_4 mixtures (1-3 atm) at 800-900℃ to produce iron carbide in the pellets. H_2S having low pressures unable to form FeS was added to the mixtures. First, reduction of iron oxides proceeded and meanwhile carbidization of metallic iron took place. The addition of traces of H_2S into gas promoted iron carbides ( Fe_3C, Orthorhombic) rather than free carbon (soot) or metallic iron as final products with nearly complete carbide conversion. The higher the temperature and the pressurization, the larger the carbidization rates. The tests without H_2S gave lower iron carbide contents with much soot or metallic iron. The addition of oxidant CO_2 or H_2O into gas suppressed iron carbides and soot. Initial carbidization rates of a reduced iron pellet coincided with a reaction rate model proposed earlier by Grabke. Influence of pressurization for H_2佑H_4 mixtures was a little smaller than that for H_2-CO mixtures.Finally, it was supposed that development of efficient iron carbide production process utilizing directly natural gas would be feasible on the basis of these findings. Less