| 摘要 |
<P>PROBLEM TO BE SOLVED: To minimize a spitting generated in the refining of molten iron by top-blowing a powder auxiliary material together with an oxygen-containing gas from a top-blown lance using a converter type refining vessel. <P>SOLUTION: A top-blown lance 5 includes: a lance inner tube 6 having a channel 6a for a mixture of an oxygen-containing gas and a powder auxiliary material; and a nozzle part 7 having a jet hole 7a installed so as to communicate with the channel 6a through a nozzle throat 8 at the tip of the lance inner tube 6. The ratio (S0/A0) of the sum total S0 of the cross sectional area of the jet hole 7a in the cross section which is orthogonal to the installation direction of the jet hole 7a in the nozzle throat 8 to the greatest cross sectional area A0 of the channel 6a is 0.1 to 0.6. A projected area A of a part 6e to a surface perpendicular to a lance central axis 6b satisfies a relation: (A/A0)≥0.40, the part 6e having an angle θ of a flat surface 9 to the lance central axis 6b of 45° or more, the flat surface 9 being in contact with an inner wall surface 6d which is located upstream of the nozzle throat 8 in the channel 6a. The powder auxiliary material is blown together with the oxygen-containing gas to molten iron from the top-blown lance 5, thereby refining the molten iron. <P>COPYRIGHT: (C)2013,JPO&INPIT |
