Deep shaft mining began during the late 18th century and progressed extensively in the UK. When the industry peaked, it came up with a rapid expansion all the way through the 19th century and early 20th century. Mined in various parts of the world, coal mining continues to be an important economic activity and at present, over 6185 million tonnes (Mt) of hard coal is produced worldwide.

Extraction methods:

Based on the quality of the seams and depth, together with geology and environmental factors, economical method of extraction is considered from coal seams. They show a discrepancy of processes depending on the operation level, whether on the surface or underground. Coals extracted by this means require washing in a coal preparation plant. Basic extraction methods include surface mining and deep underground mining.

Surface mining:

In general, seams comparatively close to the surface, with depth less than about 180 ft (50 m) are surface mined. Surface mining is preferred only when the coal seam is near the surface that is about depth less than180 feet.It is the most efficient method where 90 percent of the coal or more can be recovered. The overlying soil is excavated by explosives to expose the coal seam for extraction. The top soil and the overburden material are then removed by shovels and trucks that are saved for lateral purposes. The coal seam is then drilled, fractured and mined systematically. This is then loaded through conveyors, excavators, draglines, power shovels to extract the coal. When coal is available in the large square kilometer, the large piece of equipment is used. Machineries with bucket wheel, trucks are used to excavate the coal . The open pit or surface mining uses the land only for the temporary use, later rehabilitations of the lands are done after the extraction of the coal.

The surface techniques can be classified into contour strip mining, area strip mining, open pit mining and auger mining. Based on the nature and thickness of the strata overlying on the seams, will decide the mining methods.

In case of modern mining, the technological advancements made production more than it has ever been. In this process the coal is extracted with more efficiency. The complex machinery makes everything simple.

Underground mining :

Coal at a depth of 180 to 300 ft (50 to 100 m) is deep mined, however in some cases the technique of surface mining are implemented.

Underground mining is undergone when the coal is present at the depth of 180 to 350 feet. Room and pillar mining and longwall mining are the two types of underground mining. In case of the room and pillar mining, the network of the rooms are cut-off leaving the pillars. Only 40 percent of the coal was extracted and the remaining are extracted at the later stage. Longwall mining is more efficient when compared to the other mining. In longwall mining, coals are extracted fully from the section of the seam or the face using mechanical shears.

The length of the coal face varies from 100 to 350 m in length. This is the risky process, where the hydraulically powered system temporarily holds up the roof when the minerals are extracted. The roof is then allowed to collapse after the completion of the extraction of the coal. The capital cost of the long wall mining is generally high and is only approved when the coal is present in a large quantity.

Short wall mining is similar to that of longwall mining except the block of the coal is not more than 100 meters. After the extraction of the coal it is then sent in the conveyors for the refining process.

Having said that, different types of techniques come into play in the aforesaid extraction methods!

Production:This greatest energy resource is mined commercially in over 50 countries. Europe's coal production, when compared to Asia shows a great decline. With 16% of hard coal production being exported, most of them are used in the country of origin.

Modern mining: As with what we say as technological advancements,coal mining has become more productive.

TYPES OF COAL :

• Anthracite Coal
• Bituminous Coal
• Sub-Bituminous Coal
• Lignite Coal

Anthracite Coal mining : Anthracite coal is a form of coal that is mined from hard coal deposits and is the highest grade of coal. It is an extremely hard and shiny coal that is used for home heating and industrial purposes. The mining of anthracite coal requires special techniques and is a bit more complicated than the mining of other forms of coal.The first step in mining anthracite coal is to remove all of the overburden, which is the material that is covering the coal deposit. This is done by using large machinery to excavate and remove the material. Once the overburden is removed, the area is ready for the actual mining process.

The next step is to use explosives to break up the coal bed into small pieces. This is done by drilling holes into the coal bed, placing explosives in the holes, and then detonating the explosives. This process is called blasting. Once the coal bed has been blasted, the pieces of coal are then removed by large machinery such as draglines or shovels. The pieces are then transported to a wash plant where the coal is separated from the waste rock and dirt.

The coal is then sorted into different sizes using a process called sizing. After this process is completed, the coal is ready to be shipped and used as fuel. The mining of anthracite coal is a complicated process, but it is necessary in order to produce enough of this type of fuel to meet the demands of the world. It is an important part of the energy industry and is vital to our economy.

Bituminous Coal mining : Bituminous coal is a type of sedimentary rock formed from naturally compressed peat. It is a type of coal that has a relatively high range of carbon content and is generally harder than lignite and anthracite. It is the most common type of coal used in electricity generation in the United States and is the type of coal that is most commonly used to produce coke, which is an essential fuel and reactant in the production of steel.

Mining bituminous coal involves a variety of techniques and processes. First, a mining company must secure the rights to a certain area in order to extract the coal. Once the rights are secured, a team of geologists and engineers will conduct surveys of the area to locate the most promising coal beds. Then, a team of surveyors and miners will begin the process of extracting the coal. This is typically done through surface mining, which involves using heavy machinery to remove the top layer of soil and rock in order to expose the coal seam. Once the coal seam is exposed, miners will use a combination of pick axes, shovels, and other tools to remove the coal. The coal is then loaded onto trucks or conveyor belts and transported to the processing plant.

At the processing plant, the coal is crushed and sorted by size. The smaller pieces are then washed to remove impurities and then dried. The larger chunks of coal are usually sent to a coal-fired power plant where they are burned to generate electricity. Once the coal has been mined, processed, and burned, the residual ash is often disposed of in landfills or surface impoundments. This ash can contain heavy metals, sulfur, and other pollutants, so proper disposal is essential in order to protect the environment.

Sub-Bituminous Coal mining : Sub-bituminous coal is a type of coal that is generally black in color and dull in appearance, with a higher heating value than lignite. Sub-bituminous coal is used primarily for generating electricity and for home and industrial heating. The mining of sub-bituminous coal is similar to the mining of other types of coal, with the main difference being the depth of the coal seam. It is usually located in the western United States and Canada, and is mined using both surface and underground mining techniques.

In surface mining, large machinery is used to remove the top layers of soil and rock to expose the coal seam. Once the coal is exposed, it is then loaded onto large trucks and transported to a processing plant. In underground mining, tunnels are dug into the ground to access the coal seam. Miners use explosives to break up the coal and load it onto conveyor belts which carry it to the surface.

Once the coal is processed, it is transported to power plants for use in electricity generation or to factories for use in manufacturing and industrial processes. Sub-bituminous coal is a clean-burning and efficient form of energy. However, mining operations can have a large environmental impact, especially in terms of air pollution. Therefore, it is important for mining operations to be managed in a responsible manner to ensure that the environmental impact is minimized.

Lignite Coal mining : Lignite mining is a process that involves the extraction of lignite, a type of coal, from underground mines. Lignite is generally extracted using either surface mining or underground mining techniques. Surface mining is the most common method of extracting lignite and involves removing the soil and rock above the lignite seam and then excavating the lignite with heavy machinery. Underground mining is the more complex and expensive method and involves digging a shaft or tunnel down to the lignite seam and then extracting it with specialized equipment.

Once the lignite has been extracted, it is transported to a processing plant where it is crushed, washed, and sorted into various grades and sizes. The lignite is then loaded onto ships for transport to end markets. The lignite can either be used directly as fuel or processed into a variety of products such as briquettes or pellets, which can be used for fuel in power plants or for other industrial applications.

Lignite mining is a highly regulated activity due to the environmental and safety risks associated with it. Mining companies must adhere to a variety of regulations to ensure the safety of workers, the environment, and the surrounding communities. Special attention must also be paid to land reclamation and restoration efforts once the mine is closed.