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Hard rock mining is used for mining many ore types such as Gold , Copper , Zinc , Lead , and Diamond s. ACCESS Accessing underground Ore can be achieved via a decline or a shaft. A decline is a generally spiral tunnel which circles either the flank of the deposit or circles around the deposit. The decline begins with a Box Cut , which is the portal to the surface. A shaft is vertical and is either sunk on ore or adjacent to ore. Often a mine will have a decline for personnel and machinery access, and a shaft for ore haulage. Drives are then bored horizontally off the decline or shaft to access the ore body. Stopes are then mined from the drive, which accesses the stope from below. Vent risers are needed to provide Ventilation for the workers. Often the vent risers are used as escape routes in case of emergency. Ore chutes link drives with lower levels, where there may be a primary crushing circuit located underground. Risers and shafts are often built using raise bores. ORE EXTRACTION There are a number of mining methods that are used to extract the mineral bearing rock ( Ore ) from the uneconomic rock, also known as mullock or gangue. Typically some means of support is required in order to maintain the openings that are made by mining. This can be done by pillars which are then mined following the backfilling of the initial stopes. Local to the ore drive, rock bolts, mesh and shotcrete are used to secure working faces and the backs (tops) of the drives. However, leaving pillars of ore is wasteful, as that ore cannot be extracted and processed. Stope and retreat Using this method, mining is planned to extract rock from the stopes, and allow the wall rocks to cave in to the extracted stope after all the ore has been removed. Then, the drive is sealed. Block caving is another form of stope and retreat, used to effect with large sized orebodies which are composed of hard, stable rock. The method works best with cylindrical, vertical orebodies, where the orebody can be dropped down into the stope, which is filled with waste, the whole process removing the ore from base upwards. The roof pillar, the rock which sits above the orebody, is either left in place or removed, depending on whether the deposit outcrops at surface. Stope and fill Where large bulk ore bodies are to be mined at great depth, or where leaving pillars of ore is wasteful, the open stope can be filled with a Cement and waste rock mixture, which solidifies and forms a solid fill. This method is especially popular, as the refilled stopes provide support for the adjacent stopes, allowing total extraction of economic resources. EXTRACTION Ore must be freed from the solid rock by Blasting . This requires Drilling shot holes into the ore face. Coarse Ore is mucked out using boggers, which are similar to Skid Loaders . Gravity is used to help move it down ore raises or shafts to the lower drives. Conveyor Belts , Trucks and rarely Trains are used to haul ore to the surface along a drive or Decline . Where possible, ore is hauled by buckets in shafts. Ore is also moved in skip buckets hauled up shafts and emptied into bins beneath surface headframe towers for Transport to the mill. Open pit mining is used in shallow ore bodies, often at much lower grades of mineralization. TRIVIA
HARDROCK MINING TERMS
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