Kinetics of decomposition of mullite and corundum in coal fly ash under highly alkaline condition

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.

利用高铝粉煤灰制备莫来石微晶玻璃的实验研究

以高铝粉煤灰为主要原料，采用粉末烧结法制备出莫来石微晶玻璃。X射线衍射分析显示，经1350-1550℃热处理后，制得的微晶玻璃的主晶相均为莫来石。扫描电镜分析表明，较高的温度下热处理有利于晶体的生长。微晶玻璃的理化性能如吸水率、气孔率、体积密度．抗折强度和化学稳定性，随热处理温度的不同而发生相应的变化。1500℃热处理2h制得的微晶玻璃具有优良的理化性能，在工程和结构领域具有潜在的应用前景。

利用粉煤灰与工业氧化铝合成莫来石的研究

将处理过的粉煤灰与工业氧化铝粉按不同比例配料，经湿法磨细、加压成型后，分别在二硅化钼高温电炉及高温隧道窑内进行烧结合成莫来石的试验，获得了Ｍ７０，Ｍ６０，Ｍ５０三个系列的品种，并利用部分合成产品进行了制砖试验．结果表明：当配料中Ａｌ２Ｏ３含量为６０％左右，烧结温度为１５５０～１６００℃时，莫来石晶体的生成量最高；Ｍ７０与Ｍ６０的理化性能达到国家一级莫来石标准，可代替商业莫来石用于工业生产；