Q. Which of the following is/are the characteristic/characteristics of Indian coal?

1. High ash content
2. Low sulphur content
3. Low ash fusion temperature

Select the correct answer using the codes given below.

• 1 and 2 only
• 2 only
• 1 and 3 only
• 1, 2 and 3

Answer: (a) 1 and 2 only

Notes:

• Indian coals by their very nature are high in ash content generally 25 to 45 % whereas average ash content of imported coal varies from 10 to 20 % but low in sulphur content.
  • Indian Coal has comparatively higher ash content than imported coal due to drift theory of formation of coal deposits in India. Coal seams formed due to drift theory contains higher ash as compared to in-situ theory of formation.
• Indian coal is its high ash fusion temperature of about 1,500°C.

Classification of Coal

• Coal is originated from organic matter wood. When large tracts of forests are buried under sediments, wood is burnt and decomposed due to heat from below and pressure from above. The phenomenon makes coal but takes centuries to complete.
• Classification of Coal can be done on the basis of carbon content and time period.
• On the basis of carbon content it can be classified into the following three types:
  • Anthracite: It is the best quality of coal with the highest calorific value and carries 80 to 95% carbon content.
    • It ignites slowly with a blue flame and found in small quantities in Jammu and Kashmir.
  • Bituminous: It has a low level of moisture content with 60 to 80% of carbon content and has a high calorific value.
    • Jharkhand, West Bengal, Odisha, Chhattisgarh and Madhya Pradesh have deposits of Bituminous.
  • Lignite carries 40 to 55% carbon content and is often brown in colour with high moisture content thus, gives smoke when burnt.
    • Rajasthan, Lakhimpur (Assam) and Tamil Nadu have deposits of Lignite.
  • Peat is the first stage of transformation from wood to coal with low calorific value and less than 40% carbon content.