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采用热重分析实验技术,在O_2—N_2混合气流中,700～1200℃范围内研究了磁铁矿球团氧化过程动力学。实验发现在1100℃以下各温度反应时,氧化度X在较短时间内达到各自的某一临界值X_C后,氧化速度大为降低,X(t)趋近于饱和值。X_C值随温度的升高而增大,在1100℃以上,X_C趋近于1,于是提出了两段扩散控制的氧化过程动力学模型,得到了两段中的动力学参数的阿仑尼乌斯表达式及X_C温度间的经验关系式。应用本动力学模型模拟计算的结果与实测值取得了相当好的一致性。
The kinetics of the oxidation of magnetite pellets was investigated in the mixed gas flow of O_2-N_2 at 700-1200 ℃ by means of thermogravimetric analysis. It was found that when the oxidation degree X reaches a certain critical value X_C in a short time when the reaction temperature is below 1100 ℃, the oxidation rate is greatly reduced and X (t) approaches the saturation value. The value of X_C increases with the increase of temperature. When the temperature is above 1100 ℃, X_C approaches 1, so a two-stage diffusion-controlled oxidation process kinetic model is proposed. The kinetic parameters of the two stages of allenil Empirical Expressions and X_C Temperature Empirical Relationships. The results of simulations using this kinetic model are in good agreement with the measured values.