STEELMAKING METHOD WITH TOP-BOTTOM COMBINED BLOWING CONVERTER

摘要

PURPOSE:To reduce FeO content in slag and oxygen content in molten iron and to improve Mn yield by mixing non-oxidizing gas into oxygen supplied from a top blowing lance at the time of reaching C concn. in the molten iron to the low carbon range in a converter using the pre-treated molten iron to reduce ratio of the oxygen. CONSTITUTION:The above molten iron is charged into top-bottom combined blowing converter and inert gas of Ar, etc., is supplied from the bottom blowing tuyere and also the oxygen is supplied from the top blowing lance to execute decarbonization, and at the time of reaching to the low carbon concn. range, the non-oxidizing gas of Ar, N2, CO, CO2, etc., together with the oxygen are blown to reduce the oxygen ratio and the decarbonization is executed before the time of blowing end. Then, when the C concn. in the molten iron reaches about 0.3wt.%, the non-oxidizing gas is preferably mixed into the oxygen supplied from the top blowing lance to reduce the oxygen ratio.