| 摘要 |
PURPOSE:To heat up a molten steel to a target temp. without contaminating a molten steel with an oxide, etc. in the stage of heating up the molten steel in a ladle by immersing a cap type immersion pipe into the molten steel and adding moldings of powder graphite thereto then blowing oxygen to the molten steel from a top blowing lance. CONSTITUTION:An inert gas such as Ar is blown from a porous plug 7 provided in the ladle bottom to remove molten slag 8 from the surface of the molten steel in the ladle 1 and the cap type immersion pipe 3 is immersed into the molten steel 2 in the case of increasing the temp. of the molten steel. The moldings of about 1mm fine graphite formed by molding the same to pseudo lumps by a binder such as pitch are introduced from an introducing pipe 4 provided to the pipe 3 and oxygen is blown from a top blowing lance 6 in the immersion pipe. The relation between the height H from the top end of the lance up to the molten steel and bore diameter (d) of the lance 6 is specified at 30d>=H>=5d. The pseudo lumps of the graphite powder collapse and are burned by oxygen to heat up the molten steel 2. The resultant product of the oxidation in this case is a gaseous substance such as Co and CO2; therefore, the remaining of such product as a solid oxide in the molten steel and the consequent contamination of the molten steel are obviated and the high-temp. molten steel having high cleanliness is obtd. |
