Extraction of precious metals in fly ashes

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. Key wordsPower plant, Coal, Fly Ashes, Precious Heavy metals Introduction A precious metal is a rare, naturally occurring metallic chemical element of high economic value. Chemically, the precious metals tend to be less reactive than most elements historically; precious metals were important as currency but are now regarded mainly as investment and industrial commodities. Gold , silver, platinum, and palladium each have an ISO 4217 currency code.The best-known precious metals are the coinage metals, gold and silver. Although both have industrial uses, they are better known for their uses in art, jewellery, and coinage. Other precious metals include the platinum group metals : ruthenium, rhodium, palladium, osmium, iridium, and platinum, of which platinum is the most widely traded. The demand for precious metals is driven not only by their practical use but also by their role as investments and a store of value. Historically, precious metals have commanded much higher prices than common industrial metals.The growth of industries in developing nations has turned. prompted generation of more and more power, resulting in generation of huge amount of fly ash.