Fly Ash

News: National Thermal Power Corporation (NTPC) Limited has invited Expression of Interest (EOI) for sale of fly ash, in its endeavour to achieve 100% utilization of fly ash, from the designated plants of the Middle East and other regions. Fly Ash is a byproduct from burning of coal in the thermal power generation.

Fly Ash:

  • It is called fly ash becauseit is transported from the combustion chamber by exhaust gases.
  • It is collected from the exhaust gases by electrostatic precipitators or bag filters.
  • Anelectrostatic precipitator (ESP) is defined as a filtration device that is used to remove fine particles like smoke and fine dust from the flowing gas.
  • It is the commonly used device for air pollution control. Fly ash includes substantial amounts of silicon dioxide (SiO2), aluminium oxide (Al2O3), ferric oxide (Fe2O3) and calcium oxide (CaO).
  • Resemble Portland cementbut is chemically different. Portland cement is a binding material in the form of a finely ground powder that is manufactured by burning and grinding a mixture of limestone and clay.
  • Its chemical composition includes calcium silicates, calcium aluminate and calcium aluminoferrite.
  • Exhibit cementitious A cementitious material is one that hardens when mixed with water.
  • It is used in concrete and cement products, road base, metal recovery, and mineral filler among others.
  • Fly ash particles aretoxic air pollutants. They can trigger heart disease, cancer, respiratory diseases and stroke. When combined with water they cause leaching of heavy metals in ground water.
  • It alsopollutes the soil and affects the root development system of trees.

Fly Ash Utilisation:

  • NTPC hascollaborated with Cement manufacturers around the country to supply Fly Ash.
  • To promote the use of Fly Ash bricks in building construction, NTPC has set upFly Ash brick manufacturing Plants at its Coal based Thermal Power Plants.
  • These bricks are being utilized in Plants as well as township construction activities
  • On average, 60 million Fly Ash bricks are being manufactured annually by NTPCs own Fly Ash brick Plants.
  • As per the MoEF&CC directives, NTPC stations must keep at least 20% of total Fly Ash producedin reserve for the issue to Fly Ash brick/blocks/tiles manufacturers and issuing Fly Ash free of cost to them.
  • About 9% of the total Fly Ash produced in NTPCs stations, is being utilized by Fly Ash bricks/blocks and tiles manufacturing units annually. During the year 2020-21, almost 15 NTPC stations supplied Fly Ash to various Road projects and Ash utilization crossed by nearly 20 million tonnes.
  • Over the last five years the fly ash utilisation has grown up by 80% in the country.
  • Pradhan Mantri Awas Yojana (Urban)has focused on new construction technologies such as using fly ash bricks that are innovative, and environmentally friendly.
  • Even state governments have come out with their Fly ash utilization policies, e.g. Maharashtra was the first state to adopt the policy. Aweb portal for monitoring of fly ash generation and utilization and a mobile based application titled “ASHTRACK” has been launched by the Government.
  • GSTrates on fly ash and its products have been reduced to 5%.