Coal mining

Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content and since the 1880s, has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United States, United Kingdom, and South Africa, a coal mine and its structures are a colliery, a coal mine is called a 'pit', and the underground equipment is referred to as 'pit material'.

History

The history of coal mining goes back thousands of years, with early mines documented in ancient China, the Roman Empire, and other early historical economies. It became important in the Industrial Revolution of the 18th and 19th centuries, when it was primarily used to power steam engines, heat buildings, and generate electricity. Coal mining continues as an important economic activity today.

Methods of extraction

The methods of extracting coal from the earth vary and include deep mining and surface mining.

Surface mining

Surface mining and deep underground mining are the two basic methods of mining. The choice of mining method depends primarily on depth, density, overburden, and thickness of the coal seam; seams relatively close to the surface, at depths less than approximately 180 ft (55 m), are usually surface mined.

• Strip mining is the practice of mining a seam of mineral by first removing a long strip of overlying soil and rock (the overburden). It is most commonly used to mine coal or tar sand. Strip mining is only practical when the ore body to be excavated is relatively near the surface.
• Open-pit mining refers to a method of extracting rock or minerals from the earth through their removal from an open pit or borrow.

Underground mining

Underground mining, sometimes called deep mining, is used when the coal is buried several hundred meters below the surface. Some underground mines are 1,000 meters deep and extend for kilometers. Underground mining includes the use of tunnels or shafts.

• Room and pillar mining involves cutting rooms into the coal seam and leaving a series of wide pillars at regular intervals to support the mine roof. Once room and pillar mines have been developed to a stopping point (limited by geology, ventilation, or economics), a supplementary version of room and pillar mining, termed second mining or retreat mining, is commonly started. Miners remove the coal in the pillars, thereby recovering as much coal from the coal seam as possible.
• Longwall mining involves the full extraction of coal from a section of the seam or 'face' using mechanical shearers. The coal 'overburden' of the seam above is collapsed into the void left from mining, often causing subsidence of the surface above.

Hazards

Coal mining poses a number of significant environmental and health risks. These include the release of methane (a potent greenhouse gas), the generation of dust, and the risk of mine collapse. Coal miners are also exposed to a variety of hazardous chemicals and conditions, leading to occupational diseases like pneumoconiosis, or black lung disease.

Environmental impact

The environmental impacts of coal mining include air pollution, land degradation, and water contamination. The burning of coal contributes significantly to global warming and air pollution. To mitigate these impacts, various regulations have been implemented globally to reduce emissions from coal mining and usage.

Economic impact

Coal mining not only contributes to the local economy but also plays a significant role in the economies of many countries around the world. It provides jobs and is a source of income for many communities. However, the industry is facing challenges due to environmental concerns and the increasing availability of renewable energy sources, which are leading to a decline in coal production in some areas.

See also

• Coal seam fire
• Coal worker's pneumoconiosis
• Mining accident
• Environmental impact of the coal industry