OFF-FURNACE STEEL TREATMENT IN LADLE Russian patent published in 2003 - IPC

FIELD: ferrous metallurgy; particularly, off-furnace steel treatment in ladle. SUBSTANCE: method of offfurnace steel treatment in ladle incorporates steps of melt tapping from steelmaking unit into ladle, supply of deoxidizing agent, alloying and slag-forming materials to ladle in the course of melt tapping. Silicon carbide with fraction of 0.1-10 mm, containing 80-90 % by mass of pure silicon carbide, 2-5 % by mass of free carbon, the balance being impurities, is used as deoxidizing agent. Deoxidizing agent is supplied during tapping at consumption of 1-5 kg/t of melt depending upon the following: Q₁ = K₁•(C₂-C₁)/(Si₂-Si₁). After tapping complex deoxidizing agent is supplied at consumption within the range of 0.2-0.4 kg/t of melt and aluminum is supplied at consumption within the range of 0.1-1.5 kg/t of melt. Deoxidizing agent is supplied depending upon the following: Q₂ = K₂•(C₂-C₁)/(Si₂-Si₁), where Q₁ is consumption of complex deoxidizing agent during tapping, kg/t; Q₂ is consumption of complex deoxidizing agent after tapping, kg/t; C₁ and C₂ is content of carbon in melt at the beginning of tapping and necessary content of carbon in finished steel, % by mass; Si₁ and Si₂ is content of silicon at the beginning of tapping and necessary content of silicon in finished steel, % by mass; K1 and K2 are empirical factors equal to 1.6- 10.0 and 0.33-8.0 respectively, kg/t. Then melt is being alloyed with aluminum in the form of wire rod at consumption within the range of 0.3-0.7 kg/t of melt and rinsed with argon for 1-15 minutes at consumption of 0.5-2.0 l/min per ton. This method ensures prevention of saturation of steel with gases in the course of off-furnace steel treatment with usage of deoxidizing agents. EFFECT: reduced content of nonmetallic inclusions in steel. 1 tbl, 1 ex