The Study On Long Life Mechanism And Control Technology Of Top And Bottom Combined Blown Converter In CISC

After hot metal preprocessing and secondary refining technology achieved, long life combined blown convertor was developed in order to ensure high quality and low cost molten steel. The key to implement combined blowing technology is how to insure life-span of bottom nozzle as long as campaign of convertor. It is likelihood that convertor has long campaign by using slag splashing and slag-metal mushroom nozzle technology. considering convertor setup and steel category characteristics, analysis and study on bottom blowing flowrate,slag splashing parameter and slag property were earried out by way of presenting theoretical and practical basis for comined blown converter in CISC.Result of computation of critical bottom blowing flowrate parameter shows that minimum inlet pressure of bottom nozzle is 0.32MPa(gauge pressure)According to computation of bottom blowing flowrate (?)at insures mushroom existing stably, minimum bottom blowing flowrate was obtained.The model experiment of slag splashing of combined blown converter indicates that, top lance level is the main factor of which influences the effect of the slag splashing. Compared with top blown's, the lance of combined blown converter should be lower. Increasing with the viscosity, the slag splashing decrease, and the total slag splashing decrease. so, the evenness of the slag splashing is weakened, in the same leave. And, increasing with the quantity of slag, the discharge of top and bottom blown, the slag splashing would increase.The research of convector's final slag properties indicates that, the content of MgO in final slag, in top blown, is lower than that in bottom blown, and the content of TFe in former is higher than that in latter, and as the content of MgO in slag increased, the melting point of slag increase, significantly. The final slag mostly is grainy C₂S, and some sheet like C3S in it. In addition, there is sosoloid of calcium ferrite and magnesium ferrite, and phase RO. Increase with the slag's TFe, the low melting point calcium ferrite increases.It's efficacious for the denaturization to decrease TFe in slag. And the denaturization's melting property is better than the former one, then it's propitious to denaturize the final slag quickly. So it ensures the slag's evenness after the...