Study on the Dephosphorization Agent for Secondary Dephosphorization of Semi-steel without Vanadium

Based on a vanadium extraction converter,the semi-steel secondary dephosphorization process had been investigated,in order to improve the dephosphorization process without affecting the production schedule,thus reducing the dephosphorization pressure of the converter and decreasing the phosphorus content at the end point so as to produce the ultra-low phosphorus level in steel.The appropriate temperature,the reaction time and the addition of dephosphorizing agent which are used when the vanadium-extracted semi-steel is dephosphorized in the laboratory tube furnace are obtained by laboratory study.Based on these findings,CaO-Fe₂O₃-CaF₂ series,CaO-Fe₂O₃-CaF₂-Al2O3 series,Na₂CO₃-CaO-Fe₂O₃-CaF₂ series and BaO-CaO-Fe₂O₃-CaF₂ series dephosphorization agents are studied to find out their best matching ratio.Then the dephosphsrization process of vanadium-extracted semi-steel outside the furnace has been designed and validated by field test.