| 摘要 |
PURPOSE:To prevent decrease in temp. of a molten iron and to improve additionally the effect of dephosphorization in the stage of blowing powder to the molten iron and dephosphorizing the molten iron by blowing simultaneously a slag forming agent and iron oxide respectively with O2 and N2 as a carrier gas through the inside and outside pipes of a lance having a double-pipe construction to the molten iron. CONSTITUTION:A slag forming agent such as quicklime, fluorite, etc. is blown together with O2 via the inside pipe 1 of a lance body 4 into a molten iron and iron oxide is blown together with N2 through a blow-off port 3 into the molten iron. Then, the iron oxide blown near the high temp. region where the oxidation reaction of iron by O2 arises is decomposed to react with the slag forming agent, by which Ca is formed and therefore the efficiency of dephosphorization is considerably improved as compared to the case in which the iron oxide alone is blown to the molten iron. Since the ratio between the slag forming agent and O2 is important, the slag forming agent in a blow tank 5 is controlled in the rate of transportation while the number of revolution of a feeder 7 is controlled with the gaseous O2 controlled in the flow rate by a gaseous O2 control valve 6 as a carrier gas. |
