Longwall mining

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Longwall mining is a form of underground coal mining where a long wall of coal is mined in a single slice, typically 0.6–1.0 meters thick. The longwall panel (the block of coal that is being mined) is typically 3–4 kilometers long and 250–400 meters wide.

History

Longwall mining has been used in the United Kingdom and Europe since the 17th century. It was introduced to the United States in the early 20th century and has since become one of the most efficient methods of coal extraction.

Process

The longwall mining process involves the use of a mechanized shearer, which moves back and forth across the coal seam. The coal is then transported to the surface using a series of conveyor belts. The roof of the mine is supported by hydraulic supports, which are moved forward as the coal is extracted, allowing the roof behind to collapse in a controlled manner.

Equipment

Key equipment used in longwall mining includes:

• Shearer: A machine with large rotating drums that cut the coal from the seam.
• Armored face conveyor (AFC): A conveyor system that transports the coal from the face to the main belt conveyor.
• Hydraulic supports: Movable roof supports that protect the miners and equipment at the face.

Advantages

Longwall mining offers several advantages over other mining methods:

• Higher productivity and efficiency.
• Reduced labor costs.
• Improved safety due to the use of mechanized equipment.

Disadvantages

Despite its advantages, longwall mining also has some disadvantages:

• High initial capital investment.
• Potential for subsidence, which can affect surface structures and ecosystems.
• Limited flexibility in terms of mine layout and design.

Environmental Impact

Longwall mining can have significant environmental impacts, including:

• Subsidence: The collapse of the ground surface above the mined-out area.
• Water pollution: Contamination of groundwater and surface water due to mining activities.
• Habitat destruction: Loss of habitat for wildlife due to land disturbance.

See Also

• Room and pillar mining
• Coal mining
• Mining engineering
• Underground mining