转炉生产低磷钢的脱磷反应热力学

Thermodynamics of Dephosphorization Reaction for Producing Low Phosphorus Steel in Converter

为实现磷质量分数小于0.010%的低磷钢批量生产,系统研究了转炉脱磷反应热力学。分析了影响转炉渣-金间磷分配比LP的主要因素,研究了P2O5活度系数和脱磷反应氧分压的定量确定方式,以及碳、磷选择性氧化问题。研究结果表明:LP主要受氧分压、P2O5活度系数和温度的影响;P2O5活度系数采用修正的柯热乌罗夫规则离子溶液模型计算较为准确;脱磷反应氧分压受炉渣氧分压控制,炉渣氧分压主要取决于钢中碳含量、炉渣碱度和温度。对传统复吹转炉生产磷质量分数小于0.010%低磷钢的工艺条件是:终渣碱度w(CaO)/w(SiO2)≥3.0,终渣w(MgO)≤9.0%,终点碳w([C])≤0.065%,终点温度控制在1 873～1 923K范围。

In order to produce low phosphorus steel with w（[P]）≤0. 010%, thermodynamics of dephosphorization reation in converter was investigated systematically. The main factors of influencing phosphorus distribution ratio Le between slag and metal in converter were analyzed, the quantitative method of determining activity coefficient of P2O5 and oxygen partial pressure of dephosphorization reaction was studied, and selective oxidation problem of ear hon and phosphorus element in molten steel was also discussed. The results show that： Lp is mainly affected by oxy gen partial pressure, activity coefficient of P2O5 and reaction temperature; activity coefficient of P2O5 may be more accurately calculated by the modified Koxypob regular solution model. Dephosphorization reaction is controlled by oxygen partial pressure of the slag, which depends on carbon content in molten steel, slag basicity and temperature. For traditional combined blown converter, the process conditions of producing low phosphorus steel with w（[P]）≤0. 010% are as follows： final slag basieity w（CaO）/w（SiO2）≥3.0, the final slag w（MgO）≤9.0%, the end-point carbon content w（[C]） ≤0. 065 %, end point temperature at 1873-1 923 K range.