粉煤灰浓硫酸焙烧过程及其非等温动力学  

Roasting process and non-isothermal kinetics for sulfating roasting of coal fly ash

作　　者：刘康[1] 薛济来[1] 刘亮[1] 罗文博[1] 缪骏[1] 朱骏[1] 

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083

出　　处：《化工学报》2015年第4期1337-1343,共7页CIESC Journal

摘　　要：粉煤灰浓硫酸焙烧法提取Al2O3工艺中焙烧过程十分重要,研究发现适当提升硫酸浓度、酸灰质量比和温度可增大Al转化率,而延长焙烧时间影响并不显著;在硫酸浓度80%、酸灰质量比1.5：1、温度270℃和时间60 min条件下,Al转化率可达92%~95%。TG/DSC与XRD分析表明,焙烧过程反应主要分为3个阶段：80~206℃时形成中间产物Al（HSO4）3及H2O气化;206~241℃时生成Al（HSO4）3及Al2（SO4）3·H2O;241~304℃时由Al2（SO4）3·H2O和Al（HSO4）3二者分解转化成Al2（SO4）3。由Kissinger微分法与Ozawa积分法分别计算出3个阶段表观活化能后取二者平均值,分别为52.61、74.11、96.08 k J·mol-1,并获得频率因子、反应级数和动力学方程,所获结果可为粉煤灰硫酸焙烧法提取Al2O3焙烧工艺设计和过程优化提供理论参考和基础数据。Roasting process with sulfuric acid plays an important role in extracting Al2O3 from coal fly ash. The results indicate that Al conversion rate increases with appropriately increased acid concentration, the mass ratio of acid to ash and the roasted temperature, while the effect of roasted time is relatively small. The Al conversion rate can reach 92%—93% at recommended processing parameters： sulfuric acid concentration 80%, acid-ash mass ratio 1.5：1, roasted temperature 270℃ and roasted time 60 min. An analysis for TG/DSC and XRD data demonstrates that the roasting process can be divided to 3 steps： the first step is Al（HSO4）3 formation and water evaporation; the second the formation of Al（HSO4）3 and Al2（SO4）3·H2O, and the third Al2（SO4）3 formation from decompositions of Al2（SO4）3·H2O and Al（HSO4）3. The values of apparent activation energy for the three steps are 52.61, 74.11, and 96.08 k J·mol-1 respectively, an activation energy average of values obtained by Kissinger and Ozawa methods. Using the kinetics parameters estimated, such as activation energy, frequency factor, reaction order, three kinetic equations which correspond to three thermo-chemical reaction steps in the roasting process are established. These fundamental data and theoretical guideline provided in this paper could be used for the process design and optimization of sulfuric acid roasting process to extract alumina from coal fly ash.

关 键 词：硫酸化焙烧 粉煤灰 氧化铝 反应动力学 化学过程 

分 类 号：TF821[冶金工程—有色金属冶金]