粉煤灰的酸碱两步法溶解反应研究

Research on Dissolution of Fly Ash with Acid and Alkali in Two-step Reaction

采用先盐酸再用氢氧化钠两步溶解反应的方法,设计正交实验,研究了粉煤灰在常压、较低温度下的可溶物溶出率的最优化条件。利用X射线衍射(XRD)和扫描电镜(SEM),对原料粉煤灰、酸溶粉煤灰残渣和酸溶再碱溶粉煤灰残渣的晶相组成和微观结构进行了表征。结果表明,酸溶最优条件下,粉煤灰的溶出率为27.73w%,酸溶再碱溶最优条件下的溶出率为32.22 w%,总溶出率为51.02 w%。XRD结果表明,粉煤灰原料属于流化床粉煤灰,反应后残渣中的Fe2O3晶体峰消失,其余晶体峰的强度增大。SEM结果表明,粉煤灰原料颗粒的形状不规则,几乎没有球形;酸溶粉煤灰的残渣表面出现绒状结构,再碱溶后,残渣为连续块状结构。

Orthogonal experiments were conducted to study the optimal conditions of the dissolution of fly ash at normal pressure and lower temperature by two-step reaction method with hydrochloric acid solution followed by sodium hydroxide.XRD and SEM tests were performed to reveal the crystal phase composition and microstructure of raw fly ash,ash residue dissolved by acid,and that dissolved by acid and then alkali.The results showed that the fly ash dissolution rate under the optimal conditions reached 27.73 w%and 32.22 w%respectively.The total dissolution rate was 51.02 w%.XRD test suggested that the raw fly ash belonged to the fluidized bed,Fe2O3 disappeared in the residue after the reaction and the rest crystal peaks gained stronger intensity.SEM test found that the raw fly ash had irregular shapes with almost none spherical shape,the surface of fly ash residue was covered by fluffy structures after dissolved in acid and continuous blocky structure after being dissolved by alkali.