Coal

Coal is the most important and efficient energy fuel source mined from the nature. Coal plays a crucial role in meeting current needs directly or indirectly and is a major resource bridge to meet future goals. Coal is the most significant source for power generation worldwide. Apart from power, Coal is also used in industries such as steel, cement, fertilizers and other sectors such as bricks manufacturing, textiles and chemicals.

Coal is formed from plant remains that have been compacted, hardened, chemically altered, and metamorphosed by heat and pressure over time. It is suspected that coal was formed from prehistoric plants that grew in swamp ecosystems. In the earlier days of our Earth, the plants that lived then eventually died and Coalification began. The layers of the plant matter started accumulating at the bottom of the seabed. They helped in trapping atmospheric carbon in the ground in huge peat bogs that eventually were covered and deeply buried by sediments as a result of which those plants remain transformed into fuel. With the passing time, the chemical and physical properties of the plant remains were changed by geological action to create this solid fuel -Coal.

Coal Characteristics
Energy content and other parameters such as moisture and ash content are the most important Coal characteristics that help to determine the best application of particular types of Coal in any industries, and perhaps these characteristics are also used to differentiate the price of different qualities of coal.
As a result of geological composition, Coal is classified in 4 ranks: lignite, sub-bituminous, bituminous and anthracite.

Types of Coal

• Lignite- Lignite is brownish-black in color having a wood like texture with high moisture content and low energy density. Lignite is geologically younger than any other grade of Coal. It is lowest rank Coal; it is mainly used as fuel for electric power generation.
• Sub bituminous Coal- Has lower heating value than bituminous coal. The woody structure characteristic of lignite is absent in sub bituminous Coal. It may be dark brown or black, medium soft Coal.
• Bituminous Coal, or Steam Coal- Has higher heating value than lignite and sub-bituminous. It usually appears hard, glossy, rich black in appearance. Steam Coal is mostly environment friendly and doesn’t produce much slag in the boiler. Thereby this rank of Coal has widest application.
• Anthracite- Is the highest rank Coal, harder than any other rank of Coal, glossy and has the highest heating value. Anthracite Coal has the highest carbon content with fewest impurities compared with other rank Coal.

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