Abstract: In order to study the effects of particle size on the transformation process and path of red mud under coal-based direct reduction condition during heating process at constant rate，the thermal behavior of red mud under direct reduction conditions was studied with thermal analysis and the existence form of iron minerals in roasted products under different roasting conditions was observed with scanning electron microscopy（SEM）. Direct reduction process under coal-based condition could be mainly divided into two stages：dehydration and Fe oxides reduction. Furthermore，the reduction degrees of red mud at four particle sizes were obtained. The chemical kinetic parameters at different stages，such as appropriate kinetic mechanisms functions，activation energy and frequency factor were calculated by using the Coats-Redfern method and verified by using the Flynn-Wall-Ozawa method.

Key words: red mud, thermal analysis method, direct reduction, size distribution, reaction kinetics, diffusion

摘要： 为了得出粒度对赤泥在煤基条件下等速率加热过程中的直接还原反应的转化过程及反应动力学的影响，采用热分析技术、扫描电镜等手段研究了赤泥在直接还原过程中的热行为和不同条件下焙烧产物中铁矿物的存在形式等。实验结果发现，煤基条件下的直接还原反应主要分为赤泥脱水和铁氧化物还原两个阶段。通过计算得出了这几种粒度的赤泥的还原度，同时运用Coats-Redfern积分法推断出了试样在各个阶段的最概然机理函数和活化能、频率因子等反应动力学参数，并且用Flynn-Wall-Ozawa法对计算结果进行了验证。

关键词: 赤泥, 热分析, 直接还原, 粒度分布, 反应动力学, 扩散