Extraction of precious metals in fly ashes

Abstract

Although fly ash disposal is of environmental concern the quality of residues can be improved with respect to high value applications. Fly ash is considered as a potential source of aluminium and other strategic metals. Leaching and metal extraction behaviour of fly ash collected from Thermal Power Station have been thoroughly studied using as extractant.Coal fly ash is generated during the combustion of coal for energy production. Its utilisation as an industrial lay-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. Since Our Common Future popularized the concept of sustainable development, researchers and industrialists have searched for ways of making industrial processes.