| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for dephosphorizing molten iron, in which the molten iron having wide range of Si concentration, can be subjected to desiliconizing treatment and at the same time, dephosphorizing treatment at high efficiency in a top and bottom-blowing converter-type refining vessel, without using CaF-containing material.SOLUTION: In the method for dephosphorizing the molten iron, the molten iron is dephosphorized by top-blowing CaO-containing powdery material from a lance without using the CaF-containing material in the top and bottom-blowing converter-type refining vessel, wherein the Si concentration in the molten iron is ≥0.3 mass% and a ratio of the top-blowing speed as the pure CaO in the CaO-containing powdery material to the mass-flowing quantity as the pure-oxygen gas in the above oxygen-containing gas, is adjusted in the range represented by the following formula, 0.56+0.5×[Si]<CaO/O<0.56+1.5×[Si]. Wherein, CaO: the top-blowing speed (kg/min) as the pure CaO in the CaO-containing material, O: the mass-flowing quantity (Kg/m) as the pure oxygen gas in the oxygen-containing gas, and [Si]: the Si-concentration (mass%) in the molten iron before the treatment. |
