1990 Volume 76 Issue 11 Pages 1900-1907
A new steelmaking process composed of hot metal pretreatment, combined blowing converter and ladle refining has been developed at Kobe Works. This process has been successfully applied to mass production of high-grade steel since November 1983. Hot metal pretreatment is performed in the H furnace, which was an originally developed process using modified converter and has the ability of sequential desiliconization, dephosphorization and desulphurization within 15 minutes. In combined blowing converter, high speed and highly-accurate blowing is realized by the automatic blowing control system with sensors to detect slag condition. Ladle refining has the functions of arc heating, degassing and powder injection.
The high application ratio of hot metal pretreatment and ladle refining led to establish a highly productive, accurate and efficient refining process. In this process consistently scheduled production from blast furnace to continuous caster is assured with its highly accurate controllability of each refining station.
This paper described the improvements of combined blowing converter operation in this refining process. These improvements consist of the following items,
(1) Decrease of flux consumption
(2) Reduction of manganese ore and chromium ore
(3) Refining control by the automatic blowing control system
(4) Slag cut technique at tapping
(5) Production of super-clean steel and realized combined blowing converter operation with high productivity, high quality and low cost.