| 摘要 |
PURPOSE:To improve the yield of addition with an additive having a high vapor pressure as well and to reduce the time for treatment in a method for adding an additive simultaneously with a degassing treatment by feeding under pressure the additive, which is preliminarily melted, to the descending flow in the RH degassing treatment. CONSTITUTION:A molten additive 18 which is melted in a melting furnace is preliminarily contained in a hermetic vessel 17, and the connecting pipe part 16C of a hollow member 16 is connected to a joint 15 on the outside of the adding port 13 of a downcomer 8 provided to an RH degassing treatment tank 1. Gaseous Ar is then blown into a riser 7 to circulate the molten steel between a ladle 5 and the tank 1. The open-shut device 14 of the port 13 is opened and at the same time a valve 19 is opened to supply the pressurized gas into the vessel 17, by which the inside of the vessel 17 is pressurized and the additive 18 is fed under pressure into the descending flow 4A of the molten steel in the pipe 8 through the member 16. The purpose is attained by the above-mentioned method and in addition, the erosion of the refractory in the tank 1 is decreased and the need for washing the treating tank is eliminated in the case of treating continuously different kinds of steels. |
