What equipment is used in longwall mining?
Joy complete longwall systems represent the ultimate solution for high-production longwall mining. Joy incorporates best-in-breed shearers, roof supports, face conveyors, stageloaders, crushers, and mobile belt tail pieces to deliver a complete longwall system that is in a class of its own.
What is longwall method?
longwall mining Longwall mining is an underground method of excavating coal from tabular deposits, as well as soft mineral deposits such as potash. Large rectangular blocks of coal are defined during the development stage of the mine and are then extracted in a single continuous operation.
What is a longwall shield?
Hydraulic roof supports (shields) are an essential component of longwall mining systems. They prevent the longwall from caving and allow a safe working environment for the miners at the coal face. Furthermore, the roof supports push the conveyor system forward for the next cut and follow the mining progress.
What is Armoured face conveyor?
In coal mining: Haulage. …mechanized longwall systems is an armoured face conveyor (AFC). In addition to carrying coal from the face, the AFC serves as the guide for the longwall shearer, which rides on it (see above, Mining methods: Longwall mining).
What is longwall retreating?
A system of longwall working in which the developing headings are driven narrow to the boundary or limit line and then the coal seam is extracted by longwall faces retreating toward the shaft.
How does a longwall miner work?
It is safer and more efficient than other underground coal mining methods, and it involves extraction of large rectangular panels of coal by progressively shaving slices of coal from the longwall face, under the protection of hydraulic roof supports (Figure 1).
When did longwall mining start?
The first longwall coal mining started in the late 1600s in Great Britain and was first used in Illinois in 1856. The earliest longwall mining had all parts of the operation performed by hand and utilized many different extraction designs.
Which conveyor is suitable for face conveyor?
Cat® Armored Face Conveyors (AFCs) are designed to keep things moving and to carry the maximum possible amount of coal smoothly away from the coal face. They are designed for high availability and economy in operation.
What is beam stage loader?
The beam stage loader is simply a chain conveyor that transport coal from the AFC to the main belt conveyor. Also incorporated into the beam stage loader is a small crusher to reduce the particle size of the coal for easier transportation.
How many tons of coal can the longwall shearer produced each minute?
“Moving at a rate of up to 130 feet per minute, the shearer removes or cuts about 1,300 tons of coal for each one meter of advance in the process,” Sollars said. The shearer — and the entire longwall operation — advances 60 to 80 feet into the panel each day.
What is the difference between longwall advancing and retreating?
Advancing longwall gateroads typically require extensive maintenance to maintain the roadway cross-section (roof and floor brushing) during the life of the longwall block, whereas retreat longwall gateroads are allowed to collapse behind the retreating face.
How many longwall mines are in China?
According to statistics compiled by ZMJ (Zhenghou Mining Machinery), there are now approximately 60 longwall faces employing the ultra-thick whole seam one slice mining method of 6 m-7 m (19.7-23 ft) thick. The shields are all made by Chinese manufacturers with ZMJ accounting for more than 90% of the market.
What is the best conditions suitable for longwall method?
This technique is ideally suited to deep, very gassy coal seams with low to medium permeability (1–10 md). Its effectiveness may be reduced if the coal seam is deeper than 4000 ft where the coal seam permeability is generally less than one microdarcy.
What is Armoured chain conveyor?
The armoured face chain conveyor has large carrying capacity. It is structurally very strong, bendable and low in body height. It serves not only as a guide rail for the shearer, but also as the pivot for support advance. It transports the coal at a speed in excess of 1 metre/second.
What is BSL mining?
BSL Coal Mine is a 0.828-million tonnes per annum (Mtpa) coal mine in Musi Rawas, the province of South Sumatra, Indonesia.
How deep do you have to dig to find coal?
Coal that occurs at depths of 55 to 90 m (180 to 300 ft) are usually deep mined, but in some cases surface mining techniques can be used. For example, some western U.S. coal that occur at depths in excess of 60 m (200 ft) are mined by the open pit methods, due to thickness of the seam 20–25 metres (60–90 feet).
How does longwall coal mining work?
The basic idea of longwall mining was developed in England in the late 17th century. Miners undercut the coal along the width of the coal face, removing coal as it fell, and used wooden props to control the fall of the roof behind the face. This was known as the Shropshire method of mining.
What is creep in longwall mining?
The longwall creep displacement refers to the difference of AFC position along the moving direction between the adjacent cutting cycles shown in Figure 2.