Operation of Vacuum Slag Cleaner (VSC) for Casting Ladle

BOF slag run into casting ladle at tapping gives disadvantageous effects in the succeeding steelmaking process, such as rephosphorization, low yield of alloy, and steel contamination in the form of inclusion at the stage of casting. Conventionally at NKK Fukuyama Works, dragger was applied to eliminate the slag mechanically. This mechanical method, however, had caused imperfect slag skimming, mechanical damage to casting ladle, steel loss, and temperature drop and so on. To solve these problems, introduction of vacuum slag cleaner (VSC) for casting ladle was made. In September, 1982, NKK started the operation of VSC. And the monthly production through VSC was increased up to 50 000 tons of steel. Various effects of VSC treatment, such as reduction of aluminum consumption, less rephosphorization and better cleanliness of the steel, are discussed quantitatively in this study.