Synthesis and Characterization of Mullites From Silicoaluminous Fly Ash Waste

Abstract

Fly ash is considered one of the major hazardous pollutants around the globe. Every year a million tonnes of fly ash is disposed of into the fly ash ponds which are major sites of pollution. The major fractions of fly ash are silicates, aluminates, and ferrous substances followed by minor traces element oxides. The aluminates and silicates comprise of 70% of the fly ash. The aluminates and silicates are present in fly ash in the form of crystalline mullites and sillimanites. Mullites being inert and crystalline are retractile to mineral acids. So, here the authors have reported a novel and simple step for the recovery of all the major elements of fly ash along with recovery of mullites by using hydrofluoric acid at room temperature. The method comprises of treatment of fly ash with diluted hydrofluoric acid for 12 hours under agitation. The recovered white color mullite powder, rod shaped of size 90-300 nm, was analyzed by the sophisticated instruments for the confirmation of the mullite particles.