DEPHOSPHORIZATION METHOD OF MOLTEN PIG IRON EXCELLENT IN DEPHOSPHORIZATION EFFICIENCY

摘要

PROBLEM TO BE SOLVED: To provide a dephosphorization method of molten pig iron excellent in dephosphorization efficiency, capable of enhancing dephosphorization lime efficiency by changing conditions to other treatment condition when the molten pig iron satisfies certain conditions during a dephosphorization treatment.;SOLUTION: There is provided a dephosphorization method of molten pig iron by blowing powdery CaO source together with oxygen gas from a top blown lance to molten pig iron in a converter type reaction vessel, lance height (m) is 2.0 to 2.8, a ratio between powdery CaO blowing rate and oxygen gas flow (kg/Nm3) is 0.05 to 0.55, powdery CaO blowing rate per nozzle hole all cross section area per the molten pig iron of 1 t (kg/min/t/m2) is 0 to 210 in a first step and lance length (m) is 3.0 to 5.0, the ratio between powdery CaO blowing rate and oxygen gas flow (kg/Nm3) is 0.75 to 2.0 and slag basicity after treatment is 1.4≤(mass%CaO)/(mass%SiO₂)≤2.3 in a second step.;SELECTED DRAWING: Figure 1;COPYRIGHT: (C)2018,JPO&INPIT