longwall mining Mining. a mining method in which very long rectangular blocks of coal are defined during the development stage of the mine and then extracted in a single continuous operation by an automated cutting head moving parallel to the coal face.
What is longwall equipment?
Longwall mining is an efficient mining method and using the right equipment can make it even more profitable. Joy longwall systems incorporate shearers, roof supports, face conveyors and more into one system that can be tightly orchestrated by advanced electronics — including cutting-edge automation.
What is a longwall panel?
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 m (2 ft 0 in – 3 ft 3 in) thick). The longwall panel (the block of coal that is being mined) is typically 3–4 km (1.9–2.5 mi) long and 250–400 m (820–1,310 ft) wide.
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.
What is a longwall shearer?
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.
How much does a longwall cost?
A single longwall machine of this size costs $70 million, but at current coal prices, it pays for itself in about two months.
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.
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.
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.
What is the general length of longwall face?
1. The longwall panel is 1000 ft wide and 10,000 ft long. 2. The coal seam has an average thickness of 6 ft.
What is bord and pillar mining method?
A system of mining in which the distinguishing feature is the winning of less than 50% coal on the first working. It is more an extension of the development work than mining. The second working is similar in principle to top slicing.
What is Shortwall mining?
Abstract. The shortwall mining technique is similar to longwall mining but with shorter face lengths, ranging between 40 and 90 m, with the aim of controlling the caving nature of the overlying upper strata, the load on support and the overall operation of the supports applied at the face.
What is a GOAF?
The goaf is a mining term which refers to the part of the mine from which the mineral has been partially or completely removed.
What is coal Plough?
[′kōl ‚plau̇] (mining engineering) A device with steel blades which shears off coal and pushes it onto the face conveyor.
What is coal shearer?
A shearer consists of a machine body containing electric motors, hydraulic equipment and controls which is mounted over the AFC. Horizontal cutting drums are mounted on the face side of the machine, laced with cutting picks and rotating in a plane parallel to the face.
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.
How does longwall mining compare to room and pillar mining?
Room-and-pillar mining generally is not economical at such depths because the very large pillars are required to support the roof, which significantly reduces the amount of coal that can be recovered. Longwall mining is well suited to deep coalbeds because there is no need to support the roof.
Is longwall mining surface or subsurface?
UNDERGROUND: ROOM-AND-PILLAR MINING AND LONGWALL MINING
Underground methods are used when the coal reserve is 300 feet or more below the surface of the earth. These methods, room-and-pillar mining and longwall mining, require heavy machinery and a greater degree of capital investment than the surface-related methods.
How long is a coal face?
17,101 is the first working face of coal seam 17#, and the mining method is comprehensive mechanized backward mining of large mining height method. The length of working face is 150 m, and the propelling length is 1000 m.
How does in situ mining work?
In situ leaching (ISL), also known as solution mining, or in situ recovery (ISR) in North America, involves leaving the ore where it is in the ground, and recovering the minerals from it by dissolving them and pumping the pregnant solution to the surface where the minerals can be recovered.
What is open pit coal mining?
Open-pit mining, also known as opencast mining, is a surface mining technique that extracts minerals from an open pit in the ground. Open-pit mining is the most common method used throughout the world for mineral mining and does not require extractive methods or tunnels.
