COOLING METHOD OF LANCE FOR STIRRING MOLTEN METAL

PURPOSE:To extend the service life of a lance for stirring a molten metal and to reduce the cost ratio thereof by providing fins to the inside wall of a metallic pipe provided at the center of said lance and running gas in succession even after the treatment in use, thereby cooling effectively the metallic pipe. CONSTITUTION:A lance 3 for stirring a molten metal, consisting of a metallic pipe 7 having a gas passage hole 7' and refractories 8 covering the same 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. Fins 10 are provided on the inside wall of the pipe 7 and cooling gas is kept flowing in scccession even after the treatment in the stage of use to cool the pipe 7. Thus, the difference in thermal expansion between the pipe 7 and the refractroies 8 is decreased and the generation of the crack and stripping in the refractories 8 and the bend, etc. of the pipe 7 is prevented. Said fins 10 increase the inside surface area of the pipe 7, and if the gas is turned by providing spirally the fins, the quantity of the heat to be extracted by the gas is increased.