Desiliconization and Decarburization of Molten Pig Iron by Injection of Weakly Oxidizing Gas

Water vapor or carbon dioxide gas was injected into molten pig iron in order to oxidize silicon without oxidizing iron. When water vapor was injected, decarburization was predominant at high temperature. The oxidation of silicon occurred at low temperature of 1473 K. When carbon dioxide gas was injected, both of silicon oxidation and decarburization occurred simultaneously. But the former was predominant at lower temperature, while the latter at higher temperature, At 1523 K, the silicon content was lowered at 0.16 mass %. The oxidation of iron was not observed at all. The rate controlling step of silicon oxidation and decarburization are judged the mass transfer in the gas phase. With the increase in gas injection rate, the reaction rates decreased, because of bubble integration. The slag addition decreased the reaction rates, because the reactions were blocked on the melt surface.