Development Of Static And Kinetic Models For Steelmaking In BOF

In this paper,the research focused on the steelmaking process in a converter.Static and kinetic models of steelmaking in the converter were established from a mechanism model and practical production data.The corresponding calculation process and interface were programmed by a Visual C++ programming software.The main contents of the study can be summarized as followings:(1)The static model for the steelmaking process in the converter was established from the material balance and heat balance in the steelmaking process in the converter.The final slag basicity and(TFe)content were determined according to the target phosphorus distribution ratio and the relationship of phosphorus distribution ratio with slag composition and temperature.The consumptions of lime,cooling material and oxygen gas during the steelmaking process in the converter were calculated according to the conditions of hot metal and molten steel at tapping.(2)The calculation results of the static model were compared to the practical production data from a 100 t converter in order to verify the static model accuracy.The results showed that the hit ratio of lime within a control accuracy range of ±300 kg is 76.7%,the hit ratio of oxygen within a control accuracy range of ±300 Nm3 is 83.3%,the hit ratio of SiO2 content in end-point fluid slag within a control accuracy range of ±1%is 82.4%,the hit ratio of CaO content in end-point slag within a control accuracy range of ±1.5%is 83.3%,and the hit ratio of(TFe)content in end-point fluid slag within a control accuracy range of ±1%is 70.0%.(3)A kinetic model for the steelmaking process in the converter was established by applying the thermodynamic and kinetic principles of metallurgical reactions in the converter.The main parameters were calculated in the kinetic model.The activity coefficients of components in liquid iron were obtained based on Wagner formula.And the activity coefficients of components in molten slag were calculated by the completely ironic solution model.In addition,other kinetic parameters,such as gas-liquid mass transfer coefficients,slag-steel mass transfer coefficients,were acquired from the previous work.The changes of bulk concentration in molten steel and fluid slag with blowing time were calculated according to the Runge-Kutta Method.(4)The kinetic model calculation results were verified by the industrial production data of the 100 t converter.By comparing to the industrial data,the following results were obtained:the hit ratio of C content in end-point liquid steel within a control accuracy range of ±0.05%is 73.3%,the hit ratio of Mn content in molten steel at end-point within a control accuracy range of ±0.05%is 80.0%,the hit ratio of P content in end-point liquid steel within a control accuracy range of ±0.005%is 71.4%,the hit ratio of SiO2 percentage composition in end-point molten slag within a control accuracy range of ±1.5%is 73.3%,the hit ratio of MnO content in end-point fluid slag within a control accuracy range of ±1.0%is 70.0%,the hit ratio of(TFe)content in end-point slag within a control accuracy range of ±2,0%is 63.3%,the measured values of[%C],[%Mn]and temperature in a converter from a reference are in good agreement with the calculated values from the kinetic model within a certain extent.