Editing Open-pit mining (section)

==Extraction==
{{missing information|section| the truck and shovel mining method with specific extraction steps: drilling into benches vertically, ammonium nitrate explosive deposition, blasting, removal of material from pit walls for extracting ore, horizontal? mine expansion due to extraction of ore from walls or bottom of the pit, creation of new pits during a mine's life|date=February 2025}}
[[File:Sunrise Dam Gold Mine open pit 11.jpg|thumb|alt=Refer to caption.|Note the angled and stepped sides of the [[Sunrise Dam Gold Mine]], Australia.]]
[[File:Tagebau Garzweiler bei Otzerath Schaufelradbagger Januar2008.ogv|thumb|A bucket-wheel excavator extracting lignite from [[Garzweiler surface mine]] in Germany during 2008]]
Miners typically drill a series of test holes to locate an underground ore body. From the extracted samples, they can determine the extent of the ore. This helps them determine the likely location of the veins or benches of ore and its commercial value.<ref name=eb>{{Cite web|url=https://www.britannica.com/technology/mining|title=Mining|website=Encyclopedia Britannica|access-date=2019-04-01}}</ref> Open-pit mines that produce [[building material]]s and [[dimension stone]] are commonly referred to as [[quarries]].

Open-cast mines are dug on [[Bench (geology)|benches]], which describe vertical levels of the hole. The interval of the benches depends on the deposit being mined, the mineral being mined, and the size of the machinery that is being used. Generally, large mine benches are 12 to 15 metres thick.<ref name="Mark A. Prelas 1997 pp. 496">Mark A. Prelas; Galina Popovici; Louis K. Bigelow (23 September 1997). Handbook of Industrial Diamonds and Diamond Films. CRC Press. pp. 496–. {{ISBN|978-0-8247-9994-6}}.</ref> In contrast, many quarries do not use benches, as they are usually shallow.<ref name="Mark A. Prelas 1997 pp. 496"/> Mining can be conducted on more than one bench at a time, and access to different benches is done with a system of ramps. The width of each bench is determined by the size of the equipment being used, generally 20–40 metres wide.<ref name=eb /> Downward ramps are created to allow mining on a new level to begin. This new level will become progressively wider to form the new pit bottom.<ref name=eb />

Most walls of the pit are generally mined on an angle less than vertical. Waste rock is stripped when the pit becomes deeper, therefore this angle is a safety precaution to prevent and minimize damage and danger from rock falls. However, this depends on how weathered and eroded the rocks are, and the type of rocks involved. It also depends on the amount of structural weaknesses occur within the rocks, such as a [[Fault (geology)|fault]]s, [[Shear (geology)|shears]], joints or [[Foliation (geology)|foliations]].

The walls are stepped. The inclined section of the wall is known as the batter, and the flat part of the step is known as the bench or berm. The steps in the walls help prevent rock falls continuing down the entire face of the wall. In some instances additional ground support is required and [[rock bolt]]s, cable bolts and [[shotcrete]] are used. De-watering bores may be used to relieve water pressure by drilling horizontally into the wall, which is often enough to cause failures in the wall by itself.<ref>[http://www.mine-engineer.com/mining/open_pit.htm "Open Pit Surface Mine"] ''Mine Engineer Community'' (2000) accessed 19 December 2011</ref>

A haul road is usually situated at the side of the pit, forming a ramp up which [[truck]]s can drive, carrying [[ore]] and waste rock.<ref>G.E. Blight; A.B. Fourie; G.R. Wardle (1 January 1999). Geotechnics for Developing Africa: Proceedings of the 12th regional conference for Africa on soil mechanics and geotechnical engineering, Durban, South Africa, 25–27 October 1999. CRC Press. pp. 49–. {{ISBN|978-90-5809-082-9}}.</ref>