| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for removing silicon from a molten pig iron, while accurately grasping the progress of decarburization in the removal process. SOLUTION: It was found that when the removal step of silicon from the molten pig iron proceeds and a generation rate of a CO gas associated with decarburization reaction exceeds a given value, in a silicon removal step from the molten pig iron, the temperature of a fire point generated on the surface of the molten pig iron bath caused by blown oxygen from a lance for blowing oxygen rises, and that the progress of decarburization of the molten pig iron can be accurately grasped to some extent by catching the temperature rise of the fire point. Thereby, the objective method was completed. The method is characterized by measuring the temperature of the fire point generating on the molten pig iron bath caused by blown oxygen from the lance, with an optical fiber type radiation thermometer which is arranged at the lance for blowing oxygen, and determining a decarburization condition in the molten pig iron, based on the change of the fire point.
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