粉煤灰与几种酸固相反应特性的表面分析

用扫描电镜．能量色散谱研究了粉煤灰与酸的固相反应过程中表面形貌和化学组成变化特性。室温下粉煤灰分别与HCI、HNO3、H2SO4、HCIO4固相反应后，表面产生直径20—200nm的结晶颗粒或晶柱。反应生成的水溶物结晶体的扫描电镜图像分别呈手指状、龟背形、蛛蛛状、蝙蝠态，分别为氯化铝铁混晶、硝酸铝铁混晶、硫酸铝铁混晶和高氯酸铝铁混晶。粉煤灰是硅、铝、铁等元素的氧化物聚集体，铁铝等氧化物主要分布在颗粒表面，氧化硅主要分布在颗粒内层。用少量酸进行固相反应这些氧化物聚集体可相互剥离，用H2SO4处理粉煤灰优先将铁铝氧化物转化成可溶性硫酸盐。

Study on reaction of fly ash with acids in solid state by SEM/EDX and super FE-SEM

Changes in both of surface shape and chemical composition for fly ash,which resulted from solid-state reaction with HCl,H_2SO_4,HNO_3 and HClO_4,respectively,were studied with Scanning Electron Microscope/Energy Disperse Spectrum(SEM/EDS) and Super Field Emission-Scanning Electron Microscope(Super FE-SEM) in this paper.Crystalline substances with diameter from 20 to 200 nm were produced in reaction at the surface and made into the fly ash paste.The most crystalline substances could reaction with H_2SO_4 made the fly ash tightly pasted.SEM images of crystals resulted from dissolved solution of treated fly ash were shown as iand-like with HCl,tortoiseshell-like with HNO_3,spider-like with H_2SO_4;and bat-like with HClO_4;respectively.The crystal substances were found to be alumina salt and iron salt by Energy Disperse Spectrum.It was also shown that the fly ash was mainly composed of oxides of Silicon,Aluminum and Iron.Oxides of Aluminum and Iron were mainly distributed on the surface,while that of silicon was gathered in core.The oxides could be separated each other with a little of acids by reaction in solid state.The oxides of Aluminum and Iron were easily transformed into water dissolvable salts by H_2SO_4.