氩气氛铬铁矿含碳球团还原动力学

Reduction Kinetics of Carbon-Bearing Chromite Pellets in Ar Atmosphere

用热重法研究了铬铁矿含碳球团在氩气流中还原过程动力学,考察了还原温度、球团中配碳量和铬铁矿粉粒度等对还原过程的影响。应用颗粒模型对还原过程的实验数据进行了动力学解析,发现在本实验条件下,球团还原中对速度的限制步骤是铬铁矿颗粒还原产物层中的内扩散过程。进一步的分析步明,在 1 200℃ 以下和以上两个温度区间,该内扩散过程的活化能不同。分别求出了这两个区间的有效内扩散系数的阿仑尼乌斯表达式,得到了铬铁矿含碳球团还原过程的综合速度式。应用所获得的动力学方程对不同加热条件下的还原过程进行模拟计算,与实验结果相当符合。

Reduction kinetics of carbon-bearing chromite pellets was studied by means of thermogravimetry in argon atmosphere.Effects of reduction temperature, carbon content in pellets and particle size of pellet,on reduction process were also investigated.Experimental data resulting from the reduction process were analyzed dynamically by virtue of a particle-modelling kinetic equation. It was found that under such experimental conditions what the reduction rate is limited to in pellets' reduction process is mainly an interlamellar diffusion of reaction produts in ore particles.Further kinetic analysis reveals that in the two temperature ranges, i.e.below and above 1200℃, the activation energy in the interlamellar diffusion process has different values. Arrhenius expressions for calculating the effective diffusion coefficients are given for the two temperature ranges,respectively .thus obtaining a resultant rate equation for the reduction process. Modelling computation applying the kinetic equation obtained to the reduction process under different heating conditions shows quite in agreement with experimental results.