| 摘要 |
PROBLEM TO BE SOLVED: To provide a method by which, in the case of dephosphorizing molten iron held in a molten iron holding vessel, molten low phosphorus iron can be produced at better efficiency in comparison with the conventional method. SOLUTION: When the dephosphorization is applied to the molten iron 5 in the molten iron holding vessel 1 by blowing oxygen gas through a top-blowing lance 3 having a nozzle with one or more holes and also, injecting a lime-base dephosphorize-refining agent together with gas for carrying below the molten iron surface; from the quantity of the molten iron: W, the height of the lance: h, the top-blowing oxygen flowing quantity: Q, the outlet diameter of the nozzle: d<SB>e</SB>, the inclination of the nozzle to the vertical direction:ξand the flowing speed of the oxygen gas at the outlet of the nozzle: U<SB>e</SB>; stirring energy (ε) is 5-50 W/t obtained from the (1) formulaε=2.72×Q×d<SB>e</SB>×U<SB>e</SB><SP>2</SP>×(cosξ)<SP>2</SP>/(W×h), and in the oxygen jetting flow spouted from the nozzle, at a position where the oxygen jetting flow crosses the static molten iron surface in the case of extending the center axial line of this nozzle, the ratio of the jetting flow in the injecting range of the gas for carrying to the oxygen jetting flow spouted from the nozzle is≥30%. COPYRIGHT: (C)2009,JPO&INPIT
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