Effect of combined forms of Al and Si on the acid leaching performance of fly ash

Abstract

Research on the leaching performance of fly ash of Shanxi, Chongqing and Western Inner Mongolia. Analyze the existing forms, crystallinity and package situation of Al-Si phase in fly ash from different areas by using SEM and XRD. Effect of fractionation of Al-Si phase in fly ash on the leaching performance from the view of mechanism was investigated as well. Leaching experiments and analysis indicate that: the leaching rates of Al203 in fly ash from the there different areas are 97.41%, 68.94% and 23.61% respectively, under the conditions of solid-liquid ratio 1:20, rotary speed 500rpm, leaching time 120min, sulfate concentration 20%, particle sizes -74µm. Leaching performance of fly ash in Western Inner Mongolia is better than that in other two areas. The main reason for different leaching performance of fly ash from different areas is the difference in crystallinity, encapsulated glass phase of Al-Si phase in fly ash. The crystallinity for Western Inner Mongolia is 75.98%, while there is no non-crystalline phase in fly ash from other tow areas, The average FWHM of XRD diffraction peak of Al-Si phase are 0.641, 0.3324 and 0.1107, respectively. The crystallinity of fly ash in Western Inner Mongolia is worst among the there areas, and its content of glass phase is also lowest among them, so its activity is obviously higher than that of other two areas.