What makes coal?

Coal is mainly composed of carbon, hydrogen, oxygen and a small amount of nitrogen, sulfur or other elements. Sulfur is one of the most important impurities in coal, which usually exists in the form of sulfide in the combustion products of coal. In some countries, such as the United States, standards for controlling sulfide emissions have been established. Because the cost of removing this harmful impurity is not low, the government encourages the production of low-sulfur coal to reduce pollution.

Coal is considered to be formed by the transformation of ancient plant remains buried under the ground from peat to lignite, then to bituminous coal and then to anthracite, and anthracite can be further transformed into graphite.

Extended data:

Uses of coal:

1, coal as fuel

Coal used for coking can produce coal tar and ammonia water. Coke is an important raw material for ironmaking. Coal tar can extract many important industrial compounds. Many people think that gas is made of coal, but the fact is that gas is refined from naphtha extracted from crude oil. Coal can also be directly gasified to generate water gas (a mixture of carbon monoxide and hydrogen), which can be directly used as clean fuel.

2. Coal gasification

Coal gasification can be used to produce synthesis gas, that is, a mixture of carbon monoxide and hydrogen. Syngas is usually used for combustion in gas turbines to generate electricity, but its universality also allows it to be converted into transportation fuels such as gasoline and diesel by Fischer-Tropsch synthesis process. Sasol Chemical Company in South Africa uses coal gasification combined with Fischer-Tropsch technology to produce automobile fuel from coal and natural gas.

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