METHOD FOR TOP-BLOWING OXYGEN INTO VACUUM REFINING FURNACE BY USING STRAIGHT BARREL TYPE IMMERSION TUBE

摘要

PURPOSE: To enable the efficient decarburizing and oxygen-enriched operation and the removal of metal stuck to a vessel by top-blowing the oxygen under the specific conditions and specifying the overlapping area between bubble activating surface zone of stirring gas blown from the bottom part and the top-blowing gas. ;CONSTITUTION: Molten steel 5 tapped from a refining furnace is incorporated in a ladle 2, and an immersion tube 1 is dipped into the ladle. Successively, the pressure in the immersion tube 1 is reduced and the oxygen gas or oxidizing gas through a top-blowing lance 4 is top-blown from the upper part onto the surface of the molten steel exposed in the vacuum, and also, the inert gas is blown from a porous brick 3 at the bottom part to stir the molten steel. At this time, the top-blowing gas is blown so that a parameter Q shown by the equation Q=(F/n(h×d×p^1/2) (F: flow rate of the top-blowing gas, h: distance between the tip part of the lance and the stationary molten steel surface, d: diameter of the lance nozzle, n: number of the nozzle holes, p: atmospheric pressure) becomes 0.05-5.0. Further, the overlapping area on the molten steel surface of the bubble activating surface zone generated by the gas 6 for stirring from the bottom part and the top-blowing gas is defined as 30-90% of the cross-sectional area of the immersion tube 1.;COPYRIGHT: (C)1995,JPO