熔渣中Nb_2O_5向钢液内还原的数学模拟研究

MATHEMATICAL MODELING OF THE REDUCTION OF(Nb_2O_5)IN SLAG BY MOLTEN STEEL

本文建立了钢中 Si 还原熔渣中 Nb_2O_5的数学模型,并取实验结果对模型进行了验证.又用该模型研究了初始 Nb_2O_5浓度、初始 Si 浓度、传质系数 k_m^(nb)和渣钢接触面积 A/V 对 Nb_2O_5向钢液内还原速度的影响.结果表明:初始 Nb_2O_5浓度由10%提高到40%,Nb_2O_5的还原速度略被加快,而初始 Si 浓度由0.20%提高到0.80%后,Nb_2O_5的还原速度明显被加快了:k_m^(Nb)对(Nb_2O_5)还原速度的影响十分明显,当 k_m^(Nb)由6.2×10^(-4)cm/s 提高到5.0×10^(-3)cm/s 时,还原 Nb_2O_5的时间由38min 降为8.5min;A/V 对 Nb_2O_5还原速度的影响最为明显,A/V由0.16cm^2/cm^3提高到16cm^2/cm^3时,还原 Nb_2O_5的时间由8.5min 降为30s.

For the purpose of direct alloying using niobium oxide,it is important to understand the effects on the reduction rate of (Nb_2O_5)by factors such as[%Si],(%Nb_2O_5) mass transfer coefficient and contact area bewteen slag and molten steel.These effects can be presented clearly by a mathematical model developed in the present paper.The study of mathematical modelling reveals that: (1)When the content of (Nb_2O_5)in slag increases form 10.0% to 40.0%,the reduction rate of (Nb_2O_5)increases slightly.As the content of[Si]increases from 0.20% to 0.8%,the reduction rate increases remarkbly. (2)When the mass transfer coefficient k_m^(Nb)=6.2×10^(-4) cm/s,the reduction process takes 38min.While k_m^(Nb)=5.0×10^(-3) cm/s as mass transfer is improved,the reduction process takes only 8.5min. (3) As the contact area between slag and molten steel is inereased from 0.16cm^(-1) to 16cm^(-1),the time for reduction process approaching equilibrium decreases from 8.5 min to 30s. All the results indicate that the reduction of(Nb_2O_5)can be speeded up by controlling proper contents of[Si]and improving stirring of molten steel.