Using Coal Ash for Waste to Wealth Creation

Abstract

Introduction: Coal ash, a by-product of coal-based thermal power plants was considered a waste in past as it posed many ecological and environmental problems. From the combustion of coal, a large amount of ash is generated which are also called ‘coal ash’ or ‘fly ash’. Development often extracts a very heavy price in and around the surrounding areas where thermal power plants have come up. India ranks 4th in the world in the production of this non-virgin waste after Russia, US and China (1). Brief Discussion: The nation’s current annual production of this ash is around 250MT of which less than 50% is utilized (see Figure 1). Due to its small size and light, it has the potential to get airborne and pollute the environment. The oxides of iron and aluminum present on the surface of these ash particles attract toxic trace elements, such as Sb, As, Be, Cd, Pb, Hg, Se, V and they are found to be concentrated largely on the surface of these ashes. Also, there are reports suggesting that these ashes are more radioactive than nuclear waste. But when fly ashes are added in optimized quantities in soil & concrete, they impart beneficial properties. Indian Standards & Specifications of late starting from the mid-1970s to the early-1980s started to include the useful properties of fly ash and necessary provisions were made in various codes to initiate the practice of using coal ash especially in cement concrete. However, despite the installation of super & mega thermal power plants in later years, effective use of fly ash failed to make an impact resulting in lagging much behind the country’s declared objective of 100% ash utilization. Conclusions: Fly ash also known as mineral admixtures in construction terminology is added externally to the concrete mixture for beneficial effects (2,3). Modern-day cement concrete is different from conventional concrete by its usage of admixtures- be it chemical or mineral through various standards limits. But these limits (35% max) need to be enhanced due to the fact that sand mining has been banned in certain parts of our country and coal will continue to supply the nation’s power demand. Keywords: Ash, Coal, Cement, Concrete