| 摘要 |
PROBLEM TO BE SOLVED: To reduce the amount of the dust to be generated in a converter by suppressing generation of spitting and slopping when oxygen gas is blown against the surface of a molten iron bath in the converter from a top-blown lance to decarburize/refine the molten iron.SOLUTION: When a molten iron 11 is decarburized/refined by using a top-blown lance 1 on the tip of which a plurality of Laval nozzles 7 are disposed, the volume of a concave of the ignition point, which concave is formed on the surface of the molten iron bath by an oxygen gas jet stream injected from the top-blown lance, is defined by expression (1): V=n×L×A (in which V is the volume of the concave of the ignition point; n is the number of nozzle holes; L is the depth of the ignition point; A is the area of the ignition point). The top-blown lance is designed on the basis of such a blowing condition that the volume calculated by using the expression (1) becomes 0.5-3.0 m. The amount of the oxygen gas to be supplied and the height of the top-blown lance are adjusted so that the volume calculated by using the expression (1) becomes 0.5-3.0 m. Then, the oxygen gas is blown from the designed top-blown lance. |
