| 摘要 |
PROBLEM TO BE SOLVED: To provide a molten iron-dephosphorizing method for efficiently producing low-phosphorus steel without using fluorite. SOLUTION: When dephosphorization-blowing is performed with oxygen source and refining agent and without using fluorite as a slag formation accelerator by using a top-bottom blowing converter, a slag composition is adjusted so that the slag basicity (CaO/SiO<SB>2</SB>) is 1.80-2.40, (MnO) is 10.0-15.0 mass% and (T.Fe) is equal to or more than 8.0 mass% when finishing the dephosphorization-blowing. The dephosphorization-blowing may be performed using 2,600-4,000 watt/T bottom blowing stirring power and the refining agent may contain 2-4 kg/T Mn ore and≥4 kg/T iron ore, and the refining agent may contain powdery CaO the grain diameter of which is adjusted to≤3 mm grain diameter. The phosphrization-blowing may be performed while the powdery CaO is injected onto the molten iron in the furnace from the top-blowing lance. COPYRIGHT: (C)2010,JPO&INPIT
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