Fly ash as a soil ameliorant for improving crop production—a review

Opportunities and challenges in the use of coal fly ash for soil improvements – A review

“…Coal fly ash is comprised of very fine particles, with an average diameter <10 mm, aggregated into spherical particles of 0.01e100 mm sizes which are hollow spheres (cenospheres) filled with smaller amorphous particles or crystals (pelospheres) (Jala and Goyal, 2006). These cenospheres make CFA particles easily airborne (El-Mogazi et al, 1988).…”

“…CFAs produced from coals containing high amounts of anthracite (usually contains high amounts of sulphur, S) are acidic while that produced from lignite (usually lower in S and higher in Ca) are alkaline. Generally the coal from India is low in S but high in ash content (40%) compared to the coal produced in the US which usually is rich in S (2%) but contains only 5e10% ash (Jala and Goyal, 2006;. The S content of CFA usually varies from 0.1 to 1.5% while that of soils ranges from 0.01 to 2% (Page et al, 1979;Hodgson et al, 1982;Warren and Dudas, 1984).…”

“…Several extensive reviews on recycling of CFA have been conducted in recent years (e. g., Jala and Goyal, 2006;Basu et al, 2009;Malik and Thapliyal, 2009;Blissett and Rowson, 2012;Yunusa et al, 2012;Skousen et al, 2013;Ram and Masto, 2014). However, they have focused on the multi-component utilization of CFA with a limited coverage of the environmental challenges.…”

Separation of ultrafine particles from class F fly ashes

“…Coal properties, combustion conditions and storage methods determine the mineralogy, chemistry and physical properties of fly ash. Therefore, fly ash derived from burning of different types of coal (e.g., anthracite, bituminous and lignite coal) has different chemical compositions and physical properties [4][5].…”

“…Specific gravity of fly ash varies in the range 2.1-2.6, while bulk density ranges from 1 to 1.8 g/cm 3 [5]. Chemically, fly ash includes major (>1%), minor (1-0.1%) and trace (<0.1%) elements.…”