高铝粉煤灰在碱溶过程中的结构演变及行为

Structure Evolution of High-aluminum Coal Fly Ash during Alkaline Treatment Process

为了探究高铝粉煤灰在碱溶液中的反应规律,利用XRD和SEM等手段分析了山西某地高铝粉煤灰与氢氧化钠溶液反应前后的结构演变及行为。研究结果表明:高铝粉煤灰主要由莫来石、石英和玻璃态物质组成,其元素分布弥散。在120℃的氢氧化钠溶液中,玻璃态物质能被较快分解,而莫来石与石英溶解缓慢,并生成铝酸钠与硅酸钠,二者进一步生成钠硅渣。180℃下添加石灰时,氢氧化钠溶液浓度不低于30 g/L时才能有效分解莫来石与石英,形成铝雪硅钙石和铝酸钠。

In order to explore reaction rule of coal fly ash （ CFA ） in alkali solution, the structure evolvement and behavior of CFA from Shanxi Province before and after its reaction with sodium hydroxide solution were analyzed by X-ray diffraction （ XRD） and scanning electron microscope （ SEM） . The results showed that the compositions of CFA are predominantly mullite, quartz and vitreous phase matter, with elements dispersed. The vitreous phase matter can be easily decomposed in sodium hydroxide solution at a temperature of 120 ℃, while the mullite and quartz are dissolved slowly to form sodium silicate and sodium aluminate, which then turned to be sodalite. Furthermore, mullite and quartz can be decomposed with sodium hydroxide solution （ρ（Na2O）≥30 g/L） by adding lime at a temperature of 180 ℃, resulting in products of aluminum tobermorite and sodium aluminate.