Fly ash UPSC

Fly ash

• Ash is produced whenever combustion of solid material takes place. 

• Fly ash is one such residue which rises with the gases into the atmosphere. Fly ash is a very fi ne powder and tends to travel far in the air. The ash which does not rise is termed as bottom ash.

• Nearly 73% of India’s total installed power generation capacity is thermal, of which 90% is coal-based generation, with diesel, wind, gas, and steam making up the rest.

Composition of Fly ash

1. Aluminium silicate (in large amounts) 

2. Silicon dioxide (SiO2) and 

3. Calcium oxide (CaO).

• Fly ash particles are oxide rich and consist of silica, alumina, oxides of iron, calcium, and magnesium and toxic heavy metals like lead, arsenic, cobalt, and copper.

How Fly ash is collected?

• Fly ash is generally captured by electrostatic precipitators or other particle filtration equipments before the flue gases reach the chimneys of coal fired power plants. 

Environmental effects of Fly ash ?

• If fly ash is not captured and disposed off properly, it can pollute air and water considerably. 

• It causes respiratory problems. 

• Fly ash in the air slowly settles on leaves and crops in fields in areas near to thermal power plants and lowers the plant yield. 

Advantages of Fly ash

• Cement can be replaced by fly ash upto 35%, thus reducing the cost of construction, making roads, etc.

• Fly ash bricks are light in weight and of f er high strength and durability.

• Fly ash is a better fill material for road embankments and in concrete roads.

• Fly ash can be used in reclamation of wastelands.

• Abandoned mines can be filled up with fly ash.

• Fly ash can increase the crop yield and it also enhances water holding capacity of the land .

Policy measures of Ministry of Environment Forest & Climate Change for fly ash :

• The Ministry of Environment and Forests vide its notification in 2009, has made it mandatory to use Fly Ash based products in all construction projects, road embankment works and low lying land filling works within 100 kms radius of Thermal Power Station.

• To use Fly Ash in mine filling activities within 50 kms radius of Thermal Power Stations.