Green process using hot spring bacterium to concentrate alumina in coal fly ash

The disposal of fly ash as a by-product of incineration of coal is a more significant problem than ash produced from burning of municipal solid wastes, sugarcane bagasse, rice husks or tea dusts because of its volume. The present investigation aims at upgrading alumina in coal fly ash (CFA) through bioleaching, using Bacillus barbaricus (silicate bacterium) isolated from Taptapani hot spring, Odisha. Bioleaching has been done after washing CFA (WCFA) with water and the result obtained is compared with the results obtained by bioleaching of unwashed CFA (UCFA). The concentration of alumina in washed coal fly ash has increased to 34.72% from an initial concentration of 25.45% after 60 days. The residue also shows a reduction of silica content from an initial concentration of 62.14% to 40.71% after 60 days. All the experimental results are corroborated with chemical analysis as well as through characterization process. Thus present finding has opened an avenue for enrichment of CFA with respect to alumina which may be suitable for aluminum extraction. In addition, by-product may be used for production of silica sol. (C) 2015 Elsevier B.V. All rights reserved.