Study On Phosphorus Control Technology For Producing Low Phosphorus Steel

Phosphorus is one of the elements destroying the properties of steel product in most conditions. It needs low phosphorus content for high quality steel. Ironmaking process due to reducing atmosphere, almost has no dephosphorization capacity, thus dephosphorization during the steelmaking becomes the main mission.Based on the analysis of themodynamics and kinetics of the dephosphorization in molten steel, the industrial tests of dephosphorization with single and double slag process were carried on the180t top-bottom combined blowing converter. The effects of retaing slag with the baffle, bottom-blowing, fetting and so on on the dephosphorization were studied. Meanwhile, the industrial tests were carried on the dephosphorization effects of converter tapping. Main conclusions were got as follows.End temperature with single slag operation of the converter has obvious influence on the end phosphorus content. Consequently, the end temperature should be controlled under1690℃to ensure end phosphorus content to be≤0.010%.Since26.45%of the average FeO content in the slags is enough for dephosphorization, FeO content in the slags should be controlled. And to ensure the effects of dephosphorization, when the silicon content in the hot metal is bigger than0.6%, the slagging amount should be increased to decrease the unfavorable influence brought by high silicon content. However, if the silicon content in the hot metal is lower than0.3%, the slags will become dry which is unfavorable for dephosphorization. Hence, Silicon content in the hot metal should be controlled0.3%～0.6%.Dropping the cover of the converter and adoptting sonar forming-slags technique is helpful for dephosphorization in the biggest degree through forming primary slags earlier.