What is Coal 2020-04-08 16:44:27

What is Coal

Coal is a flammable black or brownish-black sedimentary rock, which is usually formed in lithostrata or veins known as coal beds or coal seams. Sedimentary rocks are exposed to rising temperature and pressure to form hard forms of coal that are considered metamorphic rocks, such as anthracite. Coal is believed to be formed by the transformation of ancient plant remains buried under the ground through: peat → lignite → bituminous coal → anthracite, and anthracite can be further converted into graphite.


Name: Coal

Colour: Black

Main ingredient: carbon

Properties: Carbonized fossil minerals

Uses: fuel

Coal Component

Organic matter in coal is a complex macromolecule organic compound, which is mainly composed of carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus, and the sum of carbon, hydrogen and oxygen accounts for more than 95% of organic matter. Inorganic matter in coal also contains a small amount of carbon, hydrogen, oxygen, sulfur and other elements.

Carbon is the most important component in coal, and its content increases with the deepening of coalification. The carbon content in peat is 50%-60%, lignite 60%-70%, bituminous coal 74%-92%, anthracite 90%-98%.

Sulfur is the most harmful chemical component in coal. During coal combustion, sulfur generates SO2, which pollutes the environment. So the United States has established regulations to control sulphide emissions because it is expensive to remove harmful impurities containing sulfur, so governments reward the production of low-sulfur coal to reduce pollution.

Types of Coal

According to the different carbonization degree of coal, coal is divided into peat, lignite (brown lignite, black lignite), subbituminous coal, bituminous coal (raw coal) and anthracite. The carbonization degree of anthracite is the highest and that of peat is the lowest.

Uses of Coal

Coal is used for coking and can produce coal tar and ammonia. Coke is an important raw material for ironmaking. Coal tar can extract a variety of important industrial compounds. Coal is the main fuel for heating in winter.

As an important raw material for ironmaking, coke plays a key role in the iron quality. The coal used for coking must be washed and selected to reduce the ash and sulfur content. Coke has high calorific value and does not smoke, it’s a good fuel.

Coal gasification is a production process in which coal is used as raw material and a series of chemical reactions occur between organic substances and gasifier agent in coal under high temperature and pressure in a specific equipment (such as gasifier), so as to convert solid coal into combustible gas. After gasification, coal burns more fully and is more conducive to transportation and storage.

Coal liquefaction is a process of converting coal into clean liquid fuel (gasoline, diesel oil and kerosene, etc.) and chemical raw materials (carbon fiber, binder, etc.) under special conditions. The liquefaction of coal helps to reduce the demand for natural oil.

Coal is important raw material for the production of fertilizers, plastics, synthetic rubber, synthetic fibers, explosives, dyes, medicine and other important chemical raw materials, but also an important way to obtain aromatic hydrocarbons in industry.

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