| 摘要 |
PURPOSE:To extend the service life of a lance for stirring a molten metal and to reduce the cost ratio thereof by providing a sheath pipe on the metallic pipe provided at the center of said lance, and running cooling water therein, thereby cooling the metallic pipe during the treatment and continuously even after the treatment. CONSTITUTION:A lance 3 for stirring a molten metal which consists of a metallic pipe 7 having a gas passage hole and a sheath pipe 10 for running cooling water and refractories 8 enclosing the outside circumference thereof is immersed in the molten iron 4 and slag 5 in a ladle 1, and gas and flux are blown therein to generate gas bubbling, by which the molten iron 4 is stirred and refined. Water is kept running in said pipe 10 during the treatment and even after the treatment to cool the pipe. Thus, the difference in thermal expansion between the pipe 7 and the refractories 8 and the generation of the crack and stripping in the refractories 8 and the bend, etc. of the pipe 7 is prevented. When the refractories 8 are made thin by erosion, the water is supplied to the pipe 10 only during the non-treating time and the lance is preferably cooled by air cooling during the treatment. |
