Kinetics of desilification pretreatment from high-aluminium coal fly ash in alkaline medium under pressure

Abstract

In this paper, desilification for high-aluminium coal fly ash in alkaline media under pressure was reported to improve the efficiency of sodium leaching. Factors such as the alkaline quantity, reaction temperature, time and liquid-to-solid ratio on desilification were studied in detail. At the same time, the kinetics of desilification were analysed to further reveal the leaching mechanism. The results showed that the alkaline quantity, reaction temperature and liquid-to-solid ratio had significant effects on the desilification efficiency with increasing reaction time. The maximum SiO₂ leaching rate was 65.78% under the optimal experimental conditions. According to the shrinking core model, the process of leaching is controlled by surface chemical reactions in the earlier stage and diffusion of the solid layer in the later stage.

Keywords

Kinetics / High-aluminium coal fly ash / Pressure / Desilification / Alkaline medium

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