Longwall Shearers Information
Longwall shearers cut away the face of a coal seam in longwall mining operations by mounting over an armored face conveyor (AFC). They are equipped with cutting drums positioned against the coal seam by ranging arms powered by hydraulic rams. They can weigh more than 100 tons, travel at speeds up to 30 m/min, and cut away slices of coal seams up to 100 cm thick. They can also be called shearer loaders.
Longwall mining is a type of mining where aggregate, typically coal, is extracted in panel sections of approximately 0.6-9.0 m by 200-400 m by 3-4 km. The width of the panel referred to as the face of the seam is undercut by another piece of mining equipment, such as a roadheader or continuous miner. Temporary hydraulic roof supports, also known as hydraulic chocks, are set in place at the face of the seam. Depending on the height of the seam either a shearer loader, for heights greater than 2.3 m, or a plow for thinner seams, is used. As the system advances through the panel a void, referred to as a goaf, is left behind, which collapses due to the weight of the overburden.
Video credit: Caterpillar Global Mining
Longwall shearers consist of large cutting drums mounted to a slim body. The cutting drums are used to cut a predetermined height of coal across the face of the coal seam on each pass. The shearer loader can be divided into three basic types.
- Double-ended ranging drum shearers (DERS) are the largest and most efficient type of shearer loader. The double-ended machine includes two cutting drums mounted on ranging arms that can be positioned to accommodate a range of seam thicknesses.
- Single-ended ranging drum shearers (SERS) consist of a single cutting drum mounted to a single raging arm. Typically two SERS are used simultaneously to cut away the face of a coal seam.
- Single-ended fixed drum shearer (SEFS) like SERS are also typically used in pairs, but lack a ranging arm and are used to extract thin coal seams approximately 48 inches thick.
Cutting height: Typically given as a range of seam thicknesses that can be extracted by the longwall shearer.
Installed power: The combined power supplied by one or several electrical motors for the ranging arms and cutting drums, often in Watts.
Physical dimensions: Longwall shearers are also specified by their overall length, body height, and cutting drum diameter.
Weight: The weight of the longwall shearer typically given in tons or metric tonnes must be matched to the chainless haulage system capacity.
Dr-Victor-von-Doom / CC BY SA 4.0