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Room and pillar or pillar and stall is a variant of breast stoping. It is a mining system in which the mined material is extracted across a horizontal plane, creating horizontal arrays of rooms and pillars.
Once room and pillar mines have been developed to a stopping point limited by geology, ventilation, or economics, a supplementary version of room and pillar mining, termed second mining or retreat mining, is commonly started. Miners remove the coal in the pillars, thereby recovering as much coal from the coal seam as possible.
General layout of a room-and-pillar mine. Retreat mining is the removal of pillars in the underground mining technique known as room and pillar mining.. In the first phase of room and pillar mining, tunnels are advanced into the coal or ore body in a rectangular pattern resembling city streets.
Longwall mining is a form of underground coal mining where a long wall of coal is mined in a single slice (typically 0.6–6.0 m (2 ft 0 in – 19 ft 8 in) thick). The section of rock that is being mined, known as the longwall panel, is typically 3–4 km (1.9–2.5 mi) long, but can be up to 7.5 km (4.7 mi) long and 250–400 m (820–1,310 ft) wide.
The configuration of a car body is typically determined by the layout of the engine, passenger and luggage compartments, which can be shared or separately articulated. A key design feature is the car's roof-supporting pillars, designated from front to rear of the car as A-pillar, B-pillar, C-pillar and D-pillar.
A debate has been raging about the look and style of Crocs shoes since they were first introduced in 2002, but now some schools are banning them as a safety hazard.
Three-box form Alfa Romeo Giulia (Type 105) sedan/saloon Three-box form A categorization based on overall form design using rough rectangle volumes. In the case of the three-box form, there is a "box" delineating a separate volume from the a-pillar forward, a second box comprising the passenger volume, and third box comprising the trunk area—e.g., a Sedan.
The BMW i3 electric car is one of the rare modern passenger cars with a separate body and frame design (2013). Body-on-frame is a traditional motor vehicle construction method whereby a separate body or coach is mounted on a strong and relatively rigid vehicle frame or chassis that carries the powertrain (the engine and drivetrain ) and to ...