Open-pit mining: Difference between revisions

Revision as of 22:56, 24 June 2024

Revision as of 20:07, 4 August 2024

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[[File:Ende Gelände 2017 CHB 23 (cropped).jpg|thumb|The giant [[bucket-wheel excavator]]s in the German Rhineland coal mines are among the world's biggest land vehicles.]]

'''Open-pit mining''', also known as '''open-cast''' or '''open-cut mining''' and in larger contexts '''mega-mining''',<ref>{{Cite web|last=Serafini|first=Paula|title=The Argentinian fight against 'mega mining'|url=http://theconversation.com/the-argentinian-fight-against-mega-mining-95672|access-date=2021-04-22|website=The Conversation|date=4 May 2018 }}</ref> is a [[surface mining]] technique that extracts [[rock (geology)|rock]] or [[minerals]] from the earth.{{cn|date=March 2024}}

Open-pit mines are used when deposits of commercially useful ore or rocks are found near the surface where the [[overburden]] is relatively thin. In contrast, deeper mineral deposits can be reached using underground mining.<ref>{{Cite book|url=https://www.nap.edu/read/10318/chapter/5|title=Read "Evolutionary and Revolutionary Technologies for Mining" at NAP.edu|year=2002|doi=10.17226/10318|isbn=978-0-309-07340-0}}</ref>

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[[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]].{{cn|date=March 2024}}

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 />