Classification of Coal in India
On the basis of the age of coal formation, coal reserves in India can be classified into two types – Gondwana and Tertiary. Gondwana coal is mainly found in the river basin of the Damodar, Mahanadi, Godavari and Wardha. Most of the coal of India is of this type. The coal is very old and is of much better quality and includes the coking and non-coking bituminous coal. More than 90% of the total coal reserve and production in India is of Gondwana type.
The Tertiary coal is younger in age. Tertiary group mainly includes two types – sub-bituminous and lignite. The Tertiary coal has low carbon and high percentage of moisture and sulphur.
According to quality (carbon content), the coal may be divided into following classes:
1. Anthracite: It is the best quality coal and its carbon content is as much as 92% with a low volatile matter and very little moisture. It is hard and heavy and burns with great heat.
2. Bituminous: It is also of good quality coal next to Anthracite. It’s carbon content is up to 85%. Coal mined in India, is mainly of bituminous type of Gondwana age.
3. Lignite: It is inferior quality coal, full of moisture and volatile matter. Its carbon content is less than 50%. It is also known as ‘brown coal’.
4. Peat: It is the first stage in the formation of coal. It is light and woody and has poor heating capacity.