Main-Product

Coal is a combustible black or brownish-black sedimentary rock formed over millions of years from ancient plant material subjected to heat and pressure. Composed mainly of carbon along with hydrogen, sulfur, oxygen, and nitrogen, coal is classified as a nonrenewable fossil fuel. It is primarily used for electricity generation, steel production, and as a raw material for various industrial processes.

Figure 1 — Formation of coal

Coal is categorized into four main types based on carbon content and energy value:

• Anthracite (86–97% carbon): highest energy content, used mainly in metallurgy.
• Bituminous (45–86% carbon): most abundant, used for electricity and steel production.
• Subbituminous (35–45% carbon): lower energy content, mainly for electricity generation.
• Lignite (25–35% carbon): lowest rank, high moisture, used near mining sites for power generation.

Figure 2 — Comparison of different type of coals

Coal extraction can be via surface or underground mining.

References

1. U.S. Energy Information Administration (eia). Coal explained
2. Satiendra. Anthracite Coal (Sep 8, 2018). Ispat Guru
3. Wikipedia. Coal
4. STUDENTENERGY. What is coal?
5. Australian Government, Geoscience Australia. Coal Resources (page version: Apr 30, 2019)