| 摘要 |
A refining method and refining apparatus, able to shorten the time required for refining and reduce the refining costs in decarburization refining of a chromium-contained molten steel, which refining method for chromium-contained molten steel etc. performing decarburization refining by blowing a gas containing oxygen gas into a chromium-contained molten steel under a vacuum or atmospheric pressure and vacuum, said refining method for a chromium-contained molten steel etc. characterized by having a first step for blowing oxygen gas while making the inside of the vessel a pressure of a range of 400 Torr (53 kPa) to atmospheric pressure, a second step for blowing oxygen gas while evacuating the inside of the vessel to 250 to 400 Torr (33 to 53 kPa), and third step for blowing gas while evacuating the inside of the vessel to not more than 250 Torr (33 kPa). Further, a refining method and refining apparatus for an ultra-low carbon chrome melt characterized by performing a first vacuum refining until the third step, then restoring the pressure in the vessel to at least 400 Torr (53 kPa), then performing second vacuum refining while making the bottom blowing gas blow rate at least 0.4 Nm<3>/min per ton steel.
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