METHOD OF ALLOYING IN LADLE OF LOW-CARBON STEEL Russian patent published in 1998 - IPC

FIELD: steelmaking. SUBSTANCE: invention relates to treatment in ladle of steel smelted in converter. According to invention, when low-carbon steel is alloyed in ladle with ferromanganese, metal is blown by neutral gas with uptake 0.015 to 0.4 cu.m/h t. During the blowing, ferromanganese is added into the ladle by 2-4 portions with 0.1 to 3.0 min time interval. The first portion makes up 20 to 80% of the total ferromanganese uptake, which is determined from the equation: M=(0.001-0.01)ACQ/B where M is total reagent uptake, kg; A percentage of manganese in ferromanganese; C desired content of carbon in final steel, wt %; Q weight of steel in the ladle, kg; B content of carbon in ferromanganese, wt %; and 0.001-0.01 empirical coefficient characterizing intensity of carbon deoxidation of steel, 1/%. When last portion of ferromanganese is added, metal is kept being blown by neutral gas for further 0.1 to 3.0 min, after which 1 to 3 kg/t of aluminum is added. Remaining ferromanganese is added by 1-3 supplementary portions with decreasing uptakes, each portionТs uptake being found from the equation q_m=K(M-N)/m where q_m is ferromanganese uptake in each supplementary portion, kg; m the number of supplementary portions; K empirical coefficient taking into account decrease in the quantity of added ferromanganese in each supplementary portion (equal to 1 when m=1, 1.5 and 0.5 when m=2, and 1.5, 1.0, and 0.5 when m=3); M total ferromanganese uptake, kg; and N ferromanganese uptake in the first portion. Value of m (1,2,3) is chosen in direct dependence on M value. EFFECT: facilitated process control. 2 cl, 1 tbl