Coal

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Coal

Coal (/koʊl/) is a black or brownish-black sedimentary rock that is primarily composed of carbon, along with various other elements such as hydrogen, sulfur, oxygen, and nitrogen. It is formed from the remains of plants that lived and died about 100 to 400 million years ago when parts of the earth were covered with huge swampy forests.

Etymology

The term "coal" comes from the Old English term col, which means "mineral of fossilized carbon".

Types of Coal

There are four main types of coal. They are:

  • Anthracite: The highest rank of coal. It is a hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter.
  • Bituminous: Bituminous coal is a middle rank coal between sub-bituminous and anthracite. Bituminous usually has a high heating (Btu) value and is the most common type of coal used in electricity generation in the United States.
  • Sub-bituminous: Sub-bituminous coal is black in color and dull (not shiny), and has a higher heating value than lignite.
  • Lignite: Lignite coal, aka brown coal, is the lowest grade coal with the least concentration of carbon.

Uses of Coal

Coal has many important uses worldwide. The most significant uses are in electricity generation, steel production, cement manufacturing, and as a liquid fuel.

Health Effects

Exposure to coal can have serious health effects, such as Coal Workers' Pneumoconiosis (CWP), also known as black lung disease. This condition is caused by long-term exposure to coal dust, and is common among coal miners.

See Also

External links

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