Editing Mining (section)

=== Underground mining ===
{{anchor|Underground Mining}}
{{main|Underground mining (hard rock)|Underground mining (soft rock)}}
[[File:Kilianstollen Zug.jpg|thumb|[[Mantrip]] used for transporting miners within an underground mine]]
[[File:Caterpillar Highwall Mine HW300.jpg|thumb|Caterpillar Highwall Miner HW300 – Technology Bridging Underground and Open Pit Mining]]
Sub-surface mining consists of digging tunnels or shafts into the earth to reach buried ore deposits. Ore, for processing, and waste rock, for disposal, are brought to the surface through the tunnels and shafts. Sub-surface mining can be classified by the type of access shafts used, and the extraction method or the technique used to reach the mineral deposit. [[Drift mining]] uses horizontal access tunnels, [[slope mining]] uses diagonally sloping access shafts, and [[shaft mining]] uses vertical access shafts. Mining in [[Underground mining (hard rock)|hard]] and [[Underground mining (soft rock)|soft]] rock formations requires different techniques.<ref>{{Cite conference |last=Harraz |first=Hassan Z. |date=2010 |title=Underground mining Methods |url=http://rgdoi.net/10.13140/RG.2.1.2881.1124 |doi=10.13140/RG.2.1.2881.1124}}</ref>

Other methods include [[shrinkage stope mining]], which is mining upward, creating a sloping underground room, [[long wall mining]], which is grinding a long ore surface underground, and [[room and pillar]] mining, which is removing ore from rooms while leaving pillars in place to support the roof of the room. Room and pillar mining often leads to [[retreat mining]], in which supporting pillars are removed as miners retreat, allowing the room to cave in, thereby loosening more ore. Additional sub-surface mining methods include [[underground mining (hard rock)|hard rock mining]], bore hole mining, drift and fill mining, long hole slope mining, sub level caving, and [[block caving]].{{Citation needed|date=January 2021}}