| 摘要 |
PURPOSE:To prevent the intrusion of the air to be included into a molten steel and to effectively product a low-nitrogen steel by providing discharge holes to the peripheral part of a blowing lance, discharging an inert gas upward and sealing the periphery of the lance. CONSTITUTION:Plural pieces of the inert gas discharge holes 6 are provided from the top end to the upper part of the blowing lance 1 and the inert gas is discharged upward therefrom in the directions of about 30-70 deg. angle to seal the peripheral part of the lance 1. The diameter of the holes 6 is preferably about 5-20mm and the pressure of the discharge gas is about 0.1-5kg/cm<2>. Gas such as Ar, CO2 or Ne is used as the inert gas. The intrusion of the air introduced from the furnace throat to the fire point during blowing is prevented by the above-mentioned method, by which the pickup of N in the molten steel is suppressed and the low-nitrogen steel contg. about <=10ppm N is produced. |
