转炉强底吹实现超低氧含量控制的工艺实践

Technological practice of controlling ultra-low oxygen content by strong bottom blowing of converter

马钢四钢轧300 t转炉底吹系统改造后,在炉役的前1000炉冶炼超低碳钢转炉终点碳氧积均值达到了0.0013。为了验证碳氧积的真实性,通过对此炉役同期生产的67炉超低碳钢转炉终点钢水及不脱氧出钢后钢包内钢水的碳、氧进行取样验证、转炉吹炼至平衡时烟气中CO浓度(体积含量)进行分析并通过理论计算,从理论上分析了在底吹惰性气体强度为0.12~0.20 m^(3)/(min·t)时可以实现转炉终点碳氧积为0.0013。同时发现强底吹条件下生产超低碳钢,转炉出钢过程存在着降碳增氧的现象,且由于出钢过程的钢水温度下降,钢包钢水碳氧积均低于转炉终点碳氧积。

After the transformation of 300 tons converter bottom blowing system in Masteel Company,the average carbon and oxygen equilibrium at the end of the first 1000 furnaces of ultra-low carbon steel converter reached 0.0013.In order to verify the authenticity of carbon and oxygen equilibrium,the carbon and oxygen equilibrium of 67 ultra-low carbon steel BOF end-point molten steel produced in the same period of BOF service and in ladle after non deoxidizing tapping are sampled and verified.And the volume content of CO concentration in flue gas is analyzed when BOF is blown to balance and calculated theoretically.It is proved that the carbon and oxygen equilibrium at the end of converter is 0.0013 at the bottom blowing inert gas intensity of 0.12~0.20 m^(3)/(min·t).In the production of ultra-low carbon steel under the condition of strong bottom blowing,there is a phenomenon of reducing carbon and increasing oxygen in converter tapping.Due to the temperature drop of molten steel during tapping,the carbon and oxygen equilibrium of molten steel in ladle is lower than that at the end of converter.