| 摘要 |
PURPOSE:To perform the addition of a volatile substance and the treatment of flux exactly and with high efficiency by controlling the relations between the pressure of the upper and lower spaces in a ladle, the internal pressure of a circulating container, and the head of molten metal to specific condition. CONSTITUTION:After degassing, an inert gas is sent into the ladle 1 through pressure gas supply pipe 5 after closing a shut-down valve 19 in order to pressurize the upper and lower spaces 6, whereby the circulation of molten metal 2 is kept by means of a circulating gas under a pressurized condition. At this time, the gas pressure P1 of the ladle 1 and the gas pressure P2 of the circulating container 10 are regulated by the pressure regulating valves 7 and 21 so as to keep the relation P1>P2 and also the relation P1=P2+H in order to keep the head H of the molten metal. An alloy additive is added by a hopper 22 to the molten metal to dissolve it in the metal 2 without vaporization, and then the shut-down valve 19 is opened at P2=0 and P1=1 to drive a vacuum system. Afterwards, according to the pressure P2 of the circulating container 10, P1 is lowered in conformity with P1=P2+H and lastly at P1=0, vacuum treatment is started. |
