METHOD FOR DEPHOSPHORIZING MOLTEN PIG IRON AND TOP-BLOWN LANCE FOR DEPHOSPHORIZING TREATMENT

PROBLEM TO BE SOLVED: To prevent the metal from being stuck on the inner wall surface of a vessel, and also to apply the combustion heat of CO gas in a generated exhausting gas to molten pig iron, when the molten pig iron is dephosphorized by using a converter-type vessel to supply oxygen gas from a top-blown lance. SOLUTION: When the molten iron 3 is dephosphorized by supplying the oxygen gas from a nozzle hole 18 at the tip end part while melting the metal 5 stuck on the inner wall surface by using the top-blown lance 2 having the nozzle holes at the tip end part and the side surface parts and supplying the oxygen gas from the nozzle holes 19 at the side surface parts, the nozzle holes at the side surface parts are radially disposed in several height positions and also, an angle of the nozzle hole at the side surface part disposed in the nearest position to the molten iron surface, is in the range of 30-70° downward, and angles of the nozzle holes at the side surface parts disposed in the upper part positions from the above nozzle hole are in the range of 0-50° downward and are made to smaller than the downward angle of the nozzle hole at the side surface part in the nearest position to the molten iron. COPYRIGHT: (C)2007,JPO&INPIT