Fly Ash | 17 Aug 2020

Why in News

Recently, National Thermal Power Corporation (NTPC) has developed an infrastructure to transport fly ash from power plants in bulk to cement plants, at a cheaper cost.

• It will pave the way for efficient and environment friendly transportation.
• This development is in line with NTPC's commitment towards 100% utilization of fly ash from power plants. At present, 63% of the fly ash is being utilised in India.

Key Points

• Fly Ash:
  
  • Definition: It is a byproduct from burning of coal in electric power generating plants.
    
    • It is called fly ash because it is transported from the combustion chamber by exhaust gases.
    • It is collected from the exhaust gases by electrostatic precipitators or bag filters.
  • Composition: Fly ash includes substantial amounts of silicon dioxide (SiO₂), aluminium oxide (Al₂O₃), ferric oxide (Fe₂O₃) and calcium oxide (CaO).
  • Properties:
    
    • Resemble Portland cement but 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 properties.
      
      • A cementitious material is one that hardens when mixed with water.
  • Uses: It is used in concrete and cement products, road base, metal recovery, and mineral filler among others.
  • Harmful Effects: Fly ash particles are toxic 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 also pollutes the soil, and affects the root development system of trees.

Source: PIB