氧化亚铁颗粒氢还原过程的结构演变  

Structure evolution in the reduction process of FeO powder by hydrogen

作　　者：杨晓波[1] 胡晓军[1] 陈志远[1] 党杰[1] 方飞[1] 周国治[1] 

机构地区：[1]北京科技大学钢铁冶金新技术国家重点实验室,北京100083

出　　处：《工程科学学报》2015年第2期163-167,共5页Chinese Journal of Engineering

基　　金：国家自然科学基金资助项目(51090384;50834007);北京市优秀人才培养资助项目(2010D009006000001)

摘　　要：采用热重法实验研究了773～1273K氧化亚铁的等温氢还原动力学，发现873K温度以上，反应动力学曲线有明显转折，说明反应机理发生了变化．在973～1073K的温度范围，出现了反常的温度效应．即反应速率随温度升高而减小．为讨论产物结构对反应动力学的影响，分别对不同温度的反应产物，以及一定温度不同还原状态（不同反应时间）的产物进行形貌观察．结果显示．随着反应温度升高，还原产物表面的孔洞增多，枝状特征显著增加，而973K和1023K时表面的烧结现象明显．一定温度下，随着反应进行，表面的孔洞增多，并逐渐出现烧结．973K和1023K温度条件下反应产物大体保留原来的大颗粒外形，而1173K时还原2min开始，就大量出现枝状产物，并逐渐烧结．结合产物形貌变化和反应动力学曲线，反应前期为界面化学反应控速，随着反应进行．还原的金属铁发生烧结现象，致密的结构阻碍了产物气体向外扩散，反应控速环节转变为产物气体的外扩散，还原速率也随之降低．The isothermal hydrogen reduction kinetics of FeO powder at 773 - 1273 K was investigated by thermogravimetry. Above 873 K, there was a turning point in the kinetic curve, which indicated that the reduction mechanism changed. An unusual temperature effect that the reduction rate decreased with increasing temperature was observed from 973 K to 1073 K. To discuss the effect of product structure on the reduction rate of iron oxide, the morphology of samples reduced at different temperatures and for different reaction time was observed by scanning electron microscopy. It was shown that holes on the sample surface increased gradual- ly, the dendritic characteristic appeared with increasing temperature, and the sintered phenomenon was obvious at 973 K and 1023 K. At a certain temperature, holes on the sample surface increased and the sintered phenomenon appeared gradually with prolonging reac- tion time. At 973 K and 1023 K, the sample kept fairly the original shape, but at 1173 K, just reacted for 2 rain, a large number of dendritic products appeared and sintered gradually. Combining the morphology and kinetic curves, it can be summarized that interfa- eial chemical reaction is the rate-limiting step in the initial stage of hydrogen reduction. But as the reaction proceeds, the reduced iron sinters and the compact structure of the reduced product hinders the outward diffusion of produced gas. The rate-limiting step changes to the outward diffusion of produced gas, which leads to the decrease of the reduction rate of iron oxide by hydrogen.

关 键 词：氢还原 还原动力学 温度效应 氧化亚铁 

分 类 号：TF55[冶金工程—钢铁冶金]