Kinetics study of predesilication reaction for alumina recovery from alumina rich fly ash. (May 2014)

• Record Type: Journal Article
• Authors: Liu, X. T.; Wang, B. D.; Yu, G. Z.; Xiao, Y. F.; Wang, X. W.; Zhao, L. J.; Sun, Q.
• Is Part Of: Materials research innovations. Volume 18(2014)Supplement 2
• Page Start: S541
• Page End: S546
• Publication Date: 2014-05
• Subjects: Fly ash, -- Predesilication, -- Kinetics, -- Alumina recovery; Materials -- Research -- Periodicals; Matériaux -- Recherche -- Périodiques; 620.1105
• DOI: 10.1179/1432891714Z.000000000553
• Languages: English
• ISSNs: 1432-8917

Abstract

Abstract : To recover alumina and silica from alumina rich fly ash, a predesilication process has been developed to extract glassy amorphous silica from the fly ash. The predesilication apparent reaction kinetics in 15 wt-% NaOH solution were studied. The results showed that the predesilication process followed a shrinking unreacted core model of decreasing particle size. The apparent reaction rate of the predesilication process was predominantly controlled by internal diffusion, then by chemical reaction and last by fluid film diffusion. The apparent reaction activation energy for the process was found to be 14·2 kJ mol −1 and the pre-exponential factor was 0·024. Using the leaching process, about 57·56% of glassy amorphous silica was removed from alumina rich fly ash, the silica content being reduced from 40·20 to 26·96% in the resulting dried desilicated fly ash. This study provides a theoretical foundation for the separation of alumina and silica and the design of a predesilication reactor.