| 摘要 |
PURPOSE:To easily prevent nitrogen absorption and execute ladle refining by refining the molten steel in a ladle by injection of powder and charging a carbon ic acid-contg. material to the surface of the molten steel to decompose thermally the material so that the surface of the molten steel is coated with the generated carbon dioxide. CONSTITUTION:The carbonic acid-contg. material such as limestone or dolomite is dividedly charged preferably little by little to the molten steel 2 contained in the ladle 1 via a chuter 4 and is thermally decomposed on the surface of the molten steel to generate gaseous CO2 in the stage of ladle refining consisting in subjecting the molten steel 2 to the injection of powder such as Ca alloy powder entrained in an inert gas via a lance 3 immersed into the molten steel from above and refining the molten steel. The above-mentioned gaseous CO2 expands the slag and forms a gaseous CO2 atmosphere in the idle 1 provided with a cap 6 thereby covering the surface of the molten steel 2. The nitrogen absorption from the air is thus prevented and the ladle refining of the extra-low S-, N steel is made possible. |
