低温下氢气还原氧化铁的动力学研究

Study on Kinetics of Hematite Reduction by Hydrogen at Low Temperature

用热重分析法研究了低温下不同粒度氧化铁的氢还原动力学,得出在同一温度下,铁矿粉粒度从107.5μm降到2.0μm后,由于粉体的表面积大幅度增加,提高了粉气接触面积,从而使得化学反应的速度提高了8倍左右,还原反应的表观活化能从78.3 kJ/mol降低到36.9 kJ/mol;当反应速度相同时,粒度6.5μm的粉体的反应温度比107.5μm的降低了80℃左右。同时,通过理论推导和实验结果表明,当反应扩散层厚度相同时,铁矿粉粒度越小,反应扩散层厚度越薄,其还原率越高。

The reduction kinetics of hematite with various particle sizes by hydrogen at low temperature was studied using the thermogravimetric analysis. Under the same temperature,with the decrease of particle size from 107.5 tam to 2 tam, the surface area of particles and the contact area between particles and gas increase, which make the reduction speed of hermatite increase by about 8 times, the apparent activation energy of reduction drop to 36.9 kJ/mol from 78.3 kJ/mol because of increased activity of ore particles. Under the same reaction rate, the reaction temperature of 6.5 tam powder was reduced by about 80 ℃ compared with that of 107.5 tam powder. The thinner the diffusion layer,the smaller the particle size,the higher the reduction rate is.