| 摘要 |
PROBLEM TO BE SOLVED: To provide a pretreatment apparatus for molten iron, composed of an immersion lance and a lance holder which are suitable to restrain the running cost and improve the quality of molten iron. SOLUTION: In the pretreatment apparatus of the molten iron composed of the immersion lance 8 and the lance holder 7A formed as a double tube of an inner tube 7a holding this immersion lance 8 and connected with the piping for powder-blowing, blowing the powder into the molten iron and an outer tube connected with the piping for gas-blowing, a screw-connecting part 13 for screw-connected with the immersion lance 8 at the tip part of the outer tube in the lance holder 7A is provided. A heat-insulating cover 14 is arranged so as to cover at least the screw-connecting part 13 at the tip part of the outer tube, and a cooling nozzle 16 for blowing the cooling medium C between the heat insulating cover 14 and the outer tube is disposed.
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