A kinetic study of the reaction between hot metal and soda ash

在纯碱预处理铁水过程中，纯碱与碳的反应总是作为副反应进行，影响了铁水的脱磷脱硫过程。然而，从反应动力学的角度来看，这些反应之间的相互关系还没有得到充分的认识。在本工作中，通过考察运行过程中金属和气体组成的变化，研究了碳和二氧化硅对纯碱脱磷速度的影响。结果表明：在Fe-C熔体与纯碱反应过程中，纯碱部分还原为Na蒸气，析出的气体中仅含有co。Fe-P-C熔体优先进行脱磷，金属磷含量降至0.05%后开始脱碳。当通量从5 g增加到9 g时，脱磷率增加，但当通量进一步增加到15 g时，脱碳率只增加。而在脱磷过程中产生的气体含有4 ~ 6%的<CO_2>和约50%的CO，由此计算出氧的分压<10^(-11)>atm。当助熔剂中加入二氧化硅时，可在气体中检测到40% ~ 60%的<CO_2>和百分之几的CO。结果表明，纯碱与二氧化硅的反应速度较快，大部分助熔剂中产生的<CO_2>气体不能用于铁水的脱磷脱碳。

In the pretreatment of hot metal by soda ash, the reaction between soda and carbon always proceeds as a side reaction and influences the progress of dephosphorization and desulfurization of hot metal. However, the corelation between these reactions has not been sufficiently understood from the viewpoint of reaction kinetics.In the present work, the effects of carbon and silica on the rate of dephosphorization of hot metal by soda ash were investigated by examining the change in the composition of both the metal and the gas evolved during a run. The results obtained are as follows:In the reaction between soda ash and Fe-C melt, soda ash was reduced partly to Na vapor and the gases evolved contained only CO.For Fe-P-C melts, the dephosphorization proceeded preferentially and the decarburization began after the metal phosphorus content decreased down to 0.05%. The increase in the flux amount from 5 g to 9 g resulted in the increased dephosphorization, but further increase in the flux amount to 15 g produced only the increase of the rate of decarburization.While, the gases evolved during the period of dephosphorization contained 4 to 6 % <CO_2> and about 50% CO, from which the partial pressure of oxygen was calculated to be <10^(-11)> atm.When silica was added to the flux, 40 to 60% of <CO_2> and several percent of CO were detected in the gases. This result showed that the reaction between soda ash and silica proceeded so fast and <CO_2> gas produced in the bulk of flux was not utilized for the dephosphorization and the decarburization of hot metal.