Coal Miners

The goal of coal mining is to economically remove coal from the ground. Coal is valued for its energy content. In modern times it is 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". In Australia, "colliery" generally refers to an underground coal mine.

History

Main article: History of coal mining

The oldest continuously worked deep-mine in the United Kingdom is Tower Colliery in South Wales valleys in the heart of the South Wales coalfield. This colliery was developed in 1805, and its miners bought it out at the end of the 20th century, to prevent it from being closed. Tower Colliery was finally closed on January 25, 2008, although production continues at the Aberpergwym drift mine nearby. Coal was mined in America in the early 1700s, and commercial mining occurred around 1730 in Midlothian, Virginia. Coal-cutting machines were invented in the 1880s. Before the invention, coal was mined from underground with a pick and shovel. By 1912 surface mining was conducted with steam shovels designed for coal mining.

Methods of extraction

The most economical method of coal extraction from coal seams depends on the depth and quality of the seams, and the geology and environmental factors. Coal mining processes are differentiated by whether they operate on the surface or underground. Many coals extracted from both surface and underground mines require washing in a coal preparation plant.

Technical and economic feasibility are evaluated based on: regional geologic conditions; overburden characteristics; coal seam continuity, thickness, structure, quality, and depth; strength of materials above and below the seam for roof and floor conditions; topography (especially altitude and slope); climate; land ownership as it affects the availability of land for mining and access; surface drainage patterns; ground water conditions; availability of labor and materials; coal purchaser requirements in terms of tonnage, quality, and destination; and capital investment requirements.

Surface mining and deep underground mining are the two basic methods of mining. The choice of mining method depends primarily on depth of burial and thickness of the coal seam. Seams relatively close to the surface, at depths less than approximately 180 feet (55 m), are usually surface mined. Coals that occur at depths of 180 to 300 feet (91 m) are usually deep mined but, in some cases, surface mining techniques can be used. For example, some western U.S. coals that occur at depths in excess of 200 feet (61 m) are mined by open pit methods, due to thickness of the seam (60-90 feet). Coals occurring below 300 feet (91 m) are usually deep mined.

Modern surface mining

When coal seams are near the surface, it may be economical to extract the coal using open cut (also referred to as open cast, open pit, or strip) mining methods. Open cast coal mining recovers a greater proportion of the coal deposit than underground methods, as more of the coal seams in the strata may be exploited. Large Open Cast mines can cover an area of many square kilometers and use very large pieces of equipment. This equipment can include the following: Draglines which operate by removing the overburden, power shovels, large trucks in which transport overburden and coal, bucket wheel excavators, and conveyors.

In this mining method, explosives are first use in order to break through the surface of the mining area. The coal is then removed by draglines or by shovel and truck. Once the coal seam is exposed, it is drilled, fractured and thoroughly mined in strips. The coal is then loaded on to large trucks or conveyors for transport to either the coal preparation plant or direct to where it will be used.

Most open cast mines in the United States extract bituminous coal. In Australia and South Africa open cast mining is used for both thermal and metallurgical coals. In South Wales open casting for steam coal and anthracite is practiced. Surface mining accounts for around 80% of production in Australia, while in the USA it is used for about 67% of production. Globally, about 40% of coal production involves surface mining.

Area mining

Strip mining exposes the coal by removing the overburden (the earth above the coal seam(s)) in long cuts or strips. The spoil from the first strip is deposited in an area outside the planned mining area. Spoil from subsequent cuts is deposited as fill in the previous cut after coal has been removed. Usually, the process is to drill the strip of overburden next to the previously mined strip. The drill holes are filled with explosives and blasted. The overburden is then removed using large earthmoving equipment such as draglines, shovel and trucks, excavator and trucks, or bucket-wheels and conveyors. This overburden is put into the previously mined (and now empty) strip. When all the overburden is removed, the underlying coal seam will be exposed (a 'block' of coal). This block of coal may be drilled and blasted (if hard) or otherwise loaded onto trucks or conveyors for transport to the coal preparation (or wash) plant. Once this strip is empty of coal, the process is repeated with a new strip being created next to it. This method is most suitable for areas with flat terrain.

Equipment to be used depends on geologic conditions. For example, to remove overburden that is loose or unconsolidated, a bucket wheel excavator might be the most productive. The life of some area mines may be more than 50 years.

Contour mining

The contour mining method consists of removing overburden from the seam in a pattern following the contours along a ridge or around a hillside. This method is most commonly used in areas with rolling to steep terrain. It was once common to deposit the spoil on the downslope side of the bench thus created, but this method of spoil disposal consumed much additional land and created severe landslide and erosion problems. To alleviate these problems, a variety of methods were devised to use freshly cut overburden to refill mined-out areas. These haul-back or lateral movement methods generally consist of an initial cut with the spoil deposited downslope or at some other site and spoil from the second cut refilling the first. A ridge of undisturbed natural material 15 to 20 feet (6.1 m) wide is often intentionally left at the outer edge of the mined area. This barrier adds stability to the reclaimed slope by preventing spoil from slumping or sliding downhill.

The limitations on contour strip mining are both economic and technical. When the operation reaches a predetermined stripping ratio (tons of overburden/tons of coal), it is not profitable to continue. Depending on the equipment available, it may not be technically feasible to exceed a certain height of highwall. At this point, it is possible to produce more coal with the augering method in which spiral drills bore tunnels into a highwall laterally from the bench to extract coal without removing the overburden.

Mountaintop removal mining

Main article: Mountaintop removal

Mountaintop coal mining is a surface mining practice involving removal of mountaintops to expose coal seams, and disposing of associated mining overburden in adjacent "valley fills." Valley fills occur in steep terrain where there are limited disposal alternatives. Mountaintop removal combines area and contour strip mining methods. In areas with rolling or steep terrain with a coal seam occurring near the top of a ridge or hill, the entire top is removed in a series of parallel cuts. Overburden is deposited in nearby valleys and hollows. This method usually leaves ridge and hill tops as flattened plateaus. The process is highly controversial for the drastic changes in topography, the practice of creating head-of-hollow-fills , or filling in valleys with mining debris, and for covering streams and disrupting ecosystems.

Spoil is placed at the head of a narrow, steep-sided valley or hollow. In preparation for filling this area, vegetation and soil are removed and a rock drain constructed down the middle of the area to be filled, where a natural drainage course previously existed. When the fill is completed, this underdrain will form a continuous water runoff system from the upper end of the valley to the lower end of the fill. Typical head-of-hollow fills are graded and terraced to create permanently stable slopes.

Room & Pillar Mining

Room & Pillar mining consists of coal deposits that are mined by cutting a network of rooms into the coal seam. Pillars of coal are left behind in order to keep up the roof. The Pillars can make up to forty percent of the total coal in the seam. Though, this can be extracted at a later stage

Underground mining

Main article: Underground mining (soft rock)

kentucky Coal Miners, Where They Worked and And Where They Lived

A web site to commemorate the coal miner. Coal miners where they worked , where they lived.Links to history, pictures, coal education, coal mining.

...

Coal Miners in the Past | United Mine Workers of America

Who we are Where We Work. Underground Coal Mining; Surface Coal Mining; Manufacturing; Healthcare; Public Service; UMWA in Your Community. UMWA Career Centers

...

UK miners' strike (1984–1985) - Wikipedia, the free encyclopedia

The UK Miners' Strike was a major industrial action affecting the British coal industry. It was a defining moment in British industrial relations, and its defeat significantly ...

...

Coal mining - Wikipedia, the free encyclopedia

Coal production in China is twice that in the U.S., [20] while the number of coal miners is around 50 times that of the USA, making deaths in coal mines in China 4 times as common ...

...

Coal Miners and Mining Towns: Their Stories ~ Lesson Plans ~ American ...

Overview: Students prepare, conduct, and consolidate interviews with people who work (or have worked) in the mining industry. Then they write and compile a collection of nonfiction ...

...

COAL CITY MINERS

OPEN BOARD POSITIONS . Positions available for the 2010 season are as follows: President, Cheer Director, Fundraising/PR Director, Volunteer Director, Equipment Director, and ...

...

COAL MINERS' MUSEUM (Coal Miners Museum) | MySpace - myspace.com ...

MySpace profile for Coal Miners Museum. Find friends, share photos, keep in touch with classmates, and meet new people on MySpace.

...

Amazon.com: Coal Miners' Wives: Portraits of Endurance (9780813108452 ...

This item: Coal Miners' Wives: Portraits of Endurance by Carol A. B. Giesen . In Stock. Ships from and sold by Amazon.com. Eligible for FREE Super Saver Shipping on orders over $25 ...

...

Coal Miners Urge US Congress to Improve Safety

Watch Mine Safety report / Real broadband - Download Watch Mine Safety report / Real broadband Watch Mine Safety report / Real dialup - download

...

Coal Miners

[c] The principal miners' trade union in Britain is the National Union of Mineworkers (NUM), which was established in 1944. It developed from the Mineworkers' (Miners' until 1932 ...

...