Short note on different varieties of coal?

Answer 1

There are four types of coal as under:Lignite coalUsed almost exclusively for electric power generation lignite is a young type of coal. Lignite is brownish black, has a high moisture content (up to 45 %), and a high suphur content. Lignite is more like soil than a rock and tends to disintegrate when exposed to the weather. Lignite is also called brown coal.

Lignite has a colorific value of less than 5 kw/kg approximately.

Subbituminous coalSubbituminous coal is also called black lignite. Subbituminous coal black and contains 20-30 % moisture. Subbituminous coal is used for generating electricity and space heating.

Subbitumnious coal has calorific values ranging from 5 - 6.8 kW/kG approximately.

Bituminous coal

Bituminous coal is a soft, dense, black coal. Bituminous coal often has bands of bright and dull material in it. Bituminous coal is the most common coal and has a moisture content less than 20 %. Bituminous coal is used for generating electricity, making coke, and space heating.

Bituminous coal has calorific values ranging from 6.8 - 9 kW/kG approximately.

Anthracite coal

Often referred to as hard coal, anthracite is hard, black and lustrous. Anthracite is low in suplhur and high in carbon. It is the highest rank of coal. moisture content generally is less than 15 %.

Anthracite has a calorfific values of around 9 kW/kG or above.