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Sub-surface mining - Wikipedia, the free encyclopedia

Link: Sub-surface mining - Wikipedia, the free encyclopedia.

    * Longwall mining: Longwall mining machines consist of multiple coal shearers mounted on a series of self-advancing hydraulic ceiling supports. The entire process is mechanized. Longwall mining machines are about 800 feet (240 meters) in width and 5 to 10 feet (1.5 to 3 meters) tall. Longwall miners extract "panels" - rectangular blocks of coal as wide as the mining machinery and as long as 12,000 feet (3,650 meters). Massive shearers cut coal from a wall face, which falls onto a conveyor belt for removal. As a longwall miner advances along a panel, the roof behind the miner's path is allowed to collapse.

* Room-and-pillar mining: Room and pillar mining is commonly done in flat or gently dipping bedded ores. Pillars are left in place in a regular pattern while the rooms are mined out. In many room and pillar mines, the pillars are taken out, starting at the farthest point from the mine haulage exit, retreating, and letting the roof come down upon the floor. Room and pillar methods are well adapted to mechanization, and are used in deposits such as coal, potash, phosphate, salt, oil shale, and bedded uranium ores.

Room and Pillar Mining

Link: Room and Pillar Mining.

Ramps (inclined tunnels) are excavated to connect the surface to the underground orebody. Drifts (horizontal tunnels) are excavated at different elevations to surround the orebody. Next, stopes (tunnels that have direct access to mining the ore) are mined to gain access to the ore. All tunnels are excavated by drilling and blasting. Jumbos are in charge of drilling the holes in the rocks and filling them with explosives. The loose rock, also called muck, is transported by either dump trucks or Load Haul Dump (LHD) vehicles back up to the surface for either waste disposal or processing. As mucking progresses, rooms (tunnels) are cut into the ore body. In order to provide safe roof support for mining, pillars of material around the rooms are left standing to hold up the rock ceiling above. Some parts of the mine roof can be particularly weak and fragile. In addition to pillar support, a jumbo is then brought back in for rock bolting of the roof to ensure safety. When all the ore in the stopes has been transported up to surface, some pillars can be removed, since they still have valuable mineral content, while some must be left standing to provide active support for the ceiling. In some room and pillar mines, pillars are all excavated as mining nears completion, to allow the natural collapse of the roof.

Room & Pillar Mine

Continuous Miner machine

Link: Room & Pillar Mine.

Underground Mining: Coal Miners at Work

Link: Underground Mining: Coal Miners at Work.

Underground Mining: Room and Pillar Mining

Link: Underground Mining: Room and Pillar Mining.

Underground Mining: Room and Pillar Mining

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