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用非等温热重分析法对氢气还原不同粒度细微氧化铁的动力学进行了研究。研究表明:铁矿粉粒度越小,起始反应温度越低,反应速度越快,反应达到平台期时所对应的还原率越高;平均粒度为3.5 mm的铁矿粉在400℃还原反应开始,700℃左右开始反应加快,达到平台期时的还原率为77%,而平均粒度为2μm的铁矿粉在100℃已经开始反应,350℃反应加快,达到平台期时的还原率为98%,而且在600℃时还原率就达到了100%;铁矿粉粒度从3.5 mm降到2μm后,还原反应的表观活化能从73.3 kJ/mol降低到30.46 kJ/mol;同时通过分析氢气还原氧化铁的反应机理得出,内扩散和界面化学反应均对整个反应过程起限制作用。
The kinetics of hydrogen reduction of fine iron oxides with different particle sizes by non-isothermal thermogravimetric analysis was studied. The results show that the smaller the iron ore particle size is, the lower the initial reaction temperature is, the faster the reaction rate is and the higher the reduction rate is. When the average particle size is 3.5 mm, the iron ore powder begins to reduce at 400 ℃ , The reaction started to accelerate at about 700 ℃, the reduction rate reached 77% when the plateau reached, while the iron ore powder with an average particle size of 2μm had started the reaction at 100 ℃ and the reaction accelerated at 350 ℃. The reduction rate reached 98% , And the reduction rate reached 100% at 600 ℃. The apparent activation energy of the reduction reaction decreased from 73.3 kJ / mol to 30.46 kJ / mol after the iron ore particle size decreased from 3.5 mm to 2 μm. At the same time, the hydrogen reduction The reaction mechanism of iron oxide shows that internal diffusion and interfacial chemical reactions all play a limiting role in the whole reaction process.