| 摘要 |
PURPOSE:To refine very low carbon steel by a VAD furnace only, by heating molten steel in a pressure-reduced state, and blowing oxygen toward the surface of the molten steel in a ladle through an oxygen lance which has been made to pass through the side wall of a vacuum vessel. CONSTITUTION:The inside of a vacuum vessel 1 is held in a pressure-reduced state, the inside of molten steel 5 is bubbled by blowing in inert gas 7 such as Ar or N2, etc. from the lower part of a ladle 2, and an arc is generated through an electrode 3, by which the molten steel 5 is heated. On the orther hand, decarburization is executed by blowing oxygen toward the surface of the molten steel 5 from an oxygen lance 8 inclined through the side wall of the vessel 1. When blowing of oxygen is unnecessary, for instance, at the time of heating, the lance 8 is moved backward. The lance 8 is burned out when it is used for a long period of time, therefore, it is advanced by that portion. Also, according to this method, it is also possible to execute a dephosphorization treatment. In this case, a slag for dephosphorization is thrown into the molten steel 5 through a slag throw-in hopper 6, and oxygen blow-refining is executed. |
