(1. 中国矿业大学(北京) 化学与环境工程学院，北京 100083；
2. 中国科学院 过程工程研究所 绿色过程与工程重点实验室 湿法冶金清洁技术国家工程实验室，北京 100190)
摘 要: 以内蒙古中西部地区某电厂煤粉炉高铝粉煤灰为对象，研究NaOH溶液脱除粉煤灰非晶态SiO2过程中搅拌速度、反应温度、NaOH溶液初始浓度对粉煤灰非晶态SiO2浸出率的影响，通过实验数据与液固多相反应缩芯模型拟合的方法确定动力学规律及动力学方程。结果表明：SiO2的浸出过程分为2个阶段，反应前期为表面反应控制，表观活化能为80.15 kJ/mol；反应后期为固膜扩散控制，表观活化能为29.93 kJ/mol。结合动力学实验结果及扫描电镜(SEM)、能谱(EDS)分析可知，随着反应的进行，固相产物逐渐附着于粉煤灰表面形成固膜导致控制步骤转变。
关键字: 高铝粉煤灰；脱硅；浸出；动力学；缩芯模型
（1. School of Chemical and Environmental Engineering,
China University of Mining and Technology Beijing, Beijing 100083, China;
2. National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology,
Key Laboratory of Green Process and Engineering, Institute of Process Engineering,
Chinese Academy of Sciences, Beijing 100190, China）
Abstract:Using high-aluminum fly ash from pulverized coal fired boiler in midwest of Inner Mongolia as an object, the effects of stirring speed, reaction temperature and initial NaOH concentration on the leaching rate of SiO2 in the desilication of fly ash in NaOH solution were studied. The kinetic rules and kinetic equations were confirmed by the experimental data fitting with shrinking core model of liquid-solid multiphase reaction. The results show that there are two stages in the leaching process. Earlier stage is limited by the surface reaction, and the apparent activation energy is 80.15 kJ/mol. Later stage is proven that the internal diffusion on the solid product layer is the rate-controlling step in the leaching process, and the apparent activation energy is 29.93 kJ/mol. The results of the kinetic experiment and SEM, EDS analysis show that solid product attached to the surface of fly ash leads to the rate-controlling step changes with the reaction progress.
Key words: high-aluminum fly ash; desilication; leaching; kinetics; shrinking core model
