粉煤灰中莫来石及刚玉高碱溶液分解动力学

摘要

对粉煤灰中莫来石和刚玉在高碱溶液分解动力学进行研究.考察反应温度和反应时间对莫来石和刚玉分解率及氧化铝回收效率的影响.结果表明,升高反应温度及延长反应时间有利于莫来石、刚玉分解和氧化铝回收,且莫来石的分解温度低于刚玉的分解温度.当在220℃条件下反应90 min后,1 L循环碱液可回收多于100 g氧化铝.莫来石和刚玉的分解过程符合收缩核模型,且反应速率受化学反应控制,二者的反应活化能分别为67.46和161.82 kJ/mol.%Decomposition kinetics of mullite and corundum in coal fly ash with highly alkaline solution was studied. The effects of the reaction temperature and reaction time on decomposition rates of mullite and corundum and alumina extraction efficiency were investigated. The results show that increasing reaction temperature and reaction time increases the decomposition rates of mullite and corundum and alumina extraction efficiency, with the decomposition temperature of mullite lower than that of corundum. After 90 min reaction at 220 ℃, more than 100 g alumina was extracted when recycling 1 L of alkaline solution. The decomposition processes of mullite and corundum corresponded with the shrinking unreacted core model, and the reaction rate was under chemical reaction control, with the activation energies of mullite and corundum being 67.46 and 161.82 kJ/mol, respectively.