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AssigneeKawasaki Steel Corporation
InventorsNorio Sumida, Yukio Oguchi, Tetsuya Fujii, Toshihiko Emi, Toshio Fujimura, Arata Ueda, Kenichi Orito
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A method of refining molten metal with stirring in a refining vessel by repeated operation of suction and discharge is disclosed, wherein a lower end of a refractory cylinder is immersed into a molten metal bath in the vessel and an inside of the cylinder opposite to the immersed end is alternately subjected to evacuation and pressurization. In this method, maximum and average values of pressure reduction velocity to be applied to the inside of the cylinder are limited to not more than 1,000 mmHg/sec and not more than 500 mmHg/sec, respectively, and an evacuation time is extended over at least 1.5 times intrinsic oscillation period of up and down movement of molten metal column inside the cylinder.
A method of refining molten metal with stirring by repeated operation of suction and discharge of the molten metal, the method comprising immersing a lower end of a refractory cylinder into a molten metal bath contained in a refining vessel, alternately subjecting the inside of an upper end of the cylinder opposite to the immersed lower end thereof, to pressure reduction and pressurization to forcibly stir the molten metal bath due to repeated suction of the molten metal into the cylinder and rapid discharge thereof, the pressure reduction velocity having predetermined values of not more than 1,000 mmHg/sec at an initial stage of evacuation and not more than 500 mmHg/sec at a later stage of evacuation required for obtaining a predetermined value of vacuum degree of -450 mmHg, and extending evacuation time over a period of at least 1.5 times a period of oscillation of a molten metal column having a predetermined height range in the cylinder.
Dependencies are inferred from the claim text.