焙烧温度对低硅含镁球团矿还原膨胀率的影响及机理  

Effect and mechanism of calcination temperature on reduction swelling rate of low silica magnesium pellets

作　　者：青格勒[1,2] 吴铿[1] 刘洪松 员晓 田筠清 

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 [2]首钢总公司首钢技术研究院,北京100043

出　　处：《中国有色金属学报》2015年第10期2905-2912,共8页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(51274026;51474002)

摘　　要：研究焙烧温度对Mg O含量分别为1.5%和3.0%(质量分数)的低硅含镁球团的抗压强度、矿相和还原膨胀率的影响,并基于Arrhenius方程和还原度测定计算低硅含镁球团还原反应的表观活化能,分析还原反应的速率限制性环节。结果表明:当焙烧温度较低时,低硅含镁球团内形成的铁酸镁数量较少,存在未反应的Mg O颗粒,其还原过程主要受气体扩散和界面化学反应混合控制,还原膨胀率高,还原后强度低。1280℃高温下,焙烧的低硅含镁球团形成的铁酸镁数量多、强度高,还原过程后期主要受固相扩散即铁离子扩散控制,尤其是低硅高镁球团受固相扩散控制更明显,还原过程中未出现针状铁晶粒,还原膨胀率低。The compressive strength, microstructure and reduction swelling rate of low silica magnesium pellets with 1.5% MgO and 3.0% MgO （mass fraction） calcinated at different temperatures were studied. Apparent activation energy of low silica magnesium pellets calcinated at different temperatures was also obtained by Arrhenius formula and reduction test. The rate controlling mechanism of reduction reaction was determined from apparent activation energy together. The results show that, when the calcination temperature is low, few magnesium ferrites form in low silica magnesium pellets and unreacted MgO exists, and the reduction process is controlled mainly by gas diffusion and interracial chemical reaction, which results in high reduction swelling rate and deteriorates the strength. While calcination temperature increases to 1280 ℃, there forms large amount of magnesium ferrites in pellets and the compressive strength of pellets increase significantly. Later stage of reduction reaction of low silica magnesium pellets （specially the pellets with 3.0%MGO） calcinated at high temperature is mainly controlled by solid diffusion, that is ferric ion solid diffusion, so almost no iron whiskers form, which decreases the pellet swelling rate.

关 键 词：低硅含镁球团矿 焙烧温度 还原膨胀率 表观活化能 

分 类 号：TF533[冶金工程—钢铁冶金]