A review of the multi-component utilisation of coal fly ash

Coal fly ash is generated during the combustion of coal for energy production. Its utilisation as an industrial by-product has received a great deal of attention over the past two decades as more sustainable solutions to waste problems have been sought. The present paper reviews the potential applications for coal fly ash as a raw material: as a soil amelioration agent in agriculture, in the manufacture of glass and ceramics, in the production of zeolites, in the formation of mesoporous materials, in the synthesis of geopolymers, for use as catalysts and catalyst supports, as an adsorbent for gases and waste water processes, and for the extraction of metals. The review then analyses the impact that a multi-stage process could have by examining the technology capable of a series of separations to produce hollow microspheres, enriched carbon, magnetic spheres, fine ash product, and coarse ash product. The applications for these coal fly ash derived products were also reviewed. It was found that there is significant potential for the increased utilisation of coal fly ash both in its raw and refined state. It is suggested that, by processing the coal fly ash, the scope for creating new industrial synergies is enhanced.