Coal- this is a solid, exhaustible, non-renewable mineral that a person uses to obtain heat by burning it. According to the classification, it belongs to sedimentary rocks.
What it is?
Coal as a source of energy, people began to use in antiquity along with firewood. The “flammable stone” was found on the surface of the earth, later it was purposefully mined from under it.
Coal appeared on Earth about 300-350 million years ago, when tree-like ferns flourished in primeval swamps and the first gymnosperms began to appear. Huge trunks fell into the water, gradually forming thick layers of undecomposed organic mass. Wood with limited access to oxygen did not rot, but gradually sank deeper and deeper under its weight. Over time, due to the displacement of the layers of the earth's crust, these layers sank to a considerable depth, and there, under the influence of great pressure and elevated temperature, a qualitative change took place in wood into coal.
Types of coal
Today, various types of coal are mined.
- Anthracites are the hardest grades with great depth and maximum combustion temperature.
- Coal - many varieties mined in mines and open pit. It is widely used in many areas of human activity.
- Brown coal - formed from the remains of peat, the youngest type of coal. It has the lowest combustion temperature.
All types of coal lie in layers and their locations are called coal basins.
Coal mining
At first, coal was simply collected at the places where the seam came to the surface. This could have happened as a result of the displacement of the layers of the earth's crust.
Often, after landslides in mountainous areas, such outcrops of the deposit were exposed, and people got the opportunity to get to pieces of "combustible stone".
Later, when primitive technology appeared, coal began to be developed in an open way. Some coal mines plunged to a depth of more than 300 meters.
Today, thanks to the availability of sophisticated modern technology, people descend underground into mines more than a kilometer deep. From these horizons, the highest quality and valuable coal is mined.
Where is coal used?
All types of coal can be used to generate heat. When burned, it releases much more than can be obtained from wood or other solid fuels. The hottest grades of coal are used in metallurgy, where high temperatures are needed.
In addition, coal is a valuable raw material for the chemical industry. A lot of necessary and useful substances are extracted from it.
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