Abstract: It is obtained by coexistence theory calculation and thermodynamics analysis that the slag-steel phosphorus partition ratio Lp of compound dephosphorizing slag CaO-MgO-FeO-Li₂O-Na₂O-K2O-SiO₂-P₂O₅ is obviously higher than that of basic dephosphorizing slag series CaO-MgO-FeO-SiO₂-P₂O₅ , and defined that the optimum adding lepidolite period is the early stage of BOF blowing. The results of 10 heats 120 t BOF smelting ultra-low phosphorus steel show that as compared with the heats non-adding lepidolite, the semisteel [P] of heats by adding lepidolite decreases quickly to less than 0. 044% , the semi-steel dephosphorization ratio and phosphorus partition ratio Lp respectively increase from 40. 62% and 13.13 to 67.71% and 36. 89, and the BOF average end dephosphorization ratio and phosphorus partition increase respectively from 92.35% and 130.7 to 94. 85% and 191.9, and the BOF end [P] can be controlled in 0.005% ~0. 007% with [P] percentage of hits 100% , so the compound slag series meet the requirement of ultra-low phosphorus steel production.

Key words: BOF, Dephosphorization Slag Series, Ultra-Low Phosphorus Steel, Phosphorus Partition, Lepidolite, Coexistence Theory, Commercial Test

摘要： 通过共存理论计算和热力学分析得出添加锂云母矿形成的CaO-MgO-FeO-Li₂O-Na₂O-K₂O-SiO₂-P₂O₅复合脱磷渣的渣-钢磷分配比Lp明显高于CaO-MgO-FeO-SiO₂-P₂O₅基本渣系,并确定锂云母矿的加入最佳时期是转炉吹炼前期。10炉120 t转炉冶炼的超低磷钢的结果表明,与未加锂云母矿的炉次相比,加锂云母矿可以使半钢[P]快速降低至0.044%以下,并且半钢脱磷率和磷分配比Lp分别从40.62%和13.13提高到67.71%和36.89,使转炉平均终点脱磷率和磷分配比Lp分别从92.35%和130.7提高到94.85%和191.9,转炉终点[P]可以控制在0.005%~0.007%,[P]的命中率100%,此复合渣系满足超低磷钢生产要求。