| 摘要 |
PURPOSE:To maximize the thermal efficiency of a carbon source added by specifying the grain size of a substance contg. carbon and a method for blowing the substance when the substance is added to a composite refining apparatus to increase thermal tolerance. CONSTITUTION:A substance contg. C is blown on the surface of molten iron in a vessel from a position above the surface of the molten iron through a lance while blowing a gas generating substance from the bottom of the vessel and gaseous O2 from the top to carry out composite refining. Grains of 1-10mm. grain size account for >=70% of all the grains of the substance contg. C, and this C cource is blown on the surface of the central part of the molten iron from the central part of the lance so that the blowing region does not overlap the fire spot of a jet of O2 for refining by >=30%. In carburization and decarburization periods, the ratio of the area (m<2>) of the fire spot of gaseous O2 for refining to the surface area (m<2>) of the bath is kept at >0.4. |
