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==Methods== [[Image:Cut and fill schematic.png|right|thumb|200px| Schematic diagram of cut and fill mining]] The mining method selected is determined by the size, shape, orientation and type of orebody to be mined. The orebody can be narrow vein such as a gold mine in the Witwatersrand, the orebody can be massive similar to the [[Olympic Dam mine]], South Australia, or [[Cadia-Ridgeway Mine]], [[New South Wales]]. The width or size of the orebody is determined by the grade as well as the distribution of the ore. The [[Strike and dip|dip]] of the orebody also has an influence on the mining method for example a narrow horizontal vein orebody will be mined by room and pillar or a longwall method whereas a vertical narrow vein orebody will be mined by an open stoping or cut and fill method. Further consideration is needed for the strength of the ore as well as the surrounding rock. An orebody hosted in strong self-supporting rock may be mined by an open stoping method and an orebody hosted in poor rock may need to be mined by a cut and fill method where the void is continuously filled as the ore is removed. ===Selective mining methods=== *'''Cut and fill''' mining is a method of short-hole mining used in steeply dipping or irregular ore zones, in particular where the [[hanging wall]] limits the use of long-hole methods. The ore is mined in horizontal or slightly inclined slices, and then filled with waste rock, sand or [[tailings]]. Either fill option may be cemented with binders to add cohesion to the matrix or left uncemented. Cut and fill mining is an expensive but selective method, with the advantages of low ore loss and dilution.<ref name="Underground Drilling and Loading Handbook">{{cite book | last = Puhakka | first = Tulla | title = Underground Drilling and Loading Handbook | publisher = Tamrock Corporation | year = 1997 | location = Finland | pages = 98–130 }}</ref> *'''[[Drift mining|Drift]] and fill''' is similar to cut and fill, except that it is used in ore zones, which are wider than the method of drifting will allow to be mined. In this case, the first drift is developed in the ore, and is backfilled using consolidated fill. The second drift is driven adjacent to the first drift. This carries on until the ore zone is mined out to its full width, at which time the second cut is started atop of the first cut. *'''[[Shrinkage stope mining|Shrinkage stoping]]''' is a short-hole mining method which is suitable for steeply dipping orebodies. This method is similar to cut and fill mining with the exception that after being blasted, broken ore is left in the stope where it is used to support the surrounding rock and as a platform from which to work. Only enough ore is removed from the stope to allow for drilling and blasting the next slice. The stope is emptied when all of the ore has been blasted. Although it is very selective and allows for low dilution, since most of the ore stays in the stope until mining is completed, there is a delayed return on capital investments.<ref name="Underground Drilling and Loading Handbook"/> *''' VRM'''/ '''VCR''': Vertical retreat mining (VRM) also known as Vertical crater retreat (VCR) is a method where mine is divided in vertical zones{{clarify|date=September 2015}} with depth of about 50 meters using open stoping, bottom-up mining. Long-hole large-diameter holes are drilled vertically into the ore body from the top using in-the-hole (ITH)<ref>{{Cite web |url=http://www.sciencechannel.com/tv-shows/dirty-great-machines/dirty-great-machines-videos/the-in-the-hole-drill/ |title=The In-The-Hole Drill | Dirty Great Machines | Discovery Science |access-date=2017-01-29 |archive-date=2017-02-02 |archive-url=https://web.archive.org/web/20170202064054/http://www.sciencechannel.com/tv-shows/dirty-great-machines/dirty-great-machines-videos/the-in-the-hole-drill/ |url-status=live }}</ref>{{clarify|date=September 2015}} drills, and then blasting horizontal slices of the ore body into an undercut. Ore blasted in retrieval taken in phase. This retrieval is done from bottom of the section developed. Last cleaning of ore is done through remote controlled LHD machines. A system of primary and secondary stopes is often used in VCR mining, where primary stopes are mined in the first stage and then backfilled with cemented fill to provide wall support for the blasting of successive stopes. Side chambers will be mined in pre-planned sequence after the fill has solidified.<ref>{{Cite journal |date=2008 |title=Vale Inco's Creighton mine: Digging deeper by the day |url=https://mining.cat.com/cda/files/2785508/7/Creighton_Eng.pdf.;VIEWPOINT |url-status=dead |journal=Viewpoint |issue=3 |page=2 |archive-url=https://web.archive.org/web/20150621015524/https://mining.cat.com/cda/files/2785508/7/Creighton_Eng.pdf.;VIEWPOINT |archive-date=2015-06-21 |quote=Vertical retreat mining (VRM) was introduced in the mid-1980s to replace the cut-and-fill mining method. The slot-slash mining method, a modified VRM, was introduced in the late 1990s and replaced the VRM mining.}}</ref> <ref>{{cite web|url=http://www.miningbasics.com/vertical-crater-retreat-mining-method|title=Mining & Metallurgy 101|website=www.miningbasics.com|access-date=2017-01-27|archive-date=2011-12-06|archive-url=https://web.archive.org/web/20111206201201/http://miningbasics.com/vertical-crater-retreat-mining-method|url-status=live}}</ref> === Bulk mining methods {{anchor|Block Caving}} === *'''Block caving''' is used to mine massive steeply [[Strike and dip|dipping]] orebodies (typically low grade) with high [[friability]]. An undercut with haulage access is driven under the orebody, with "drawbells" excavated between the top of the haulage level and the bottom of the undercut. The drawbells serve as a place for caving rock to fall into. The orebody is drilled and blasted above the undercut, and the ore is removed via the haulage access. Due to the friability of the orebody the ore above the first blast caves and falls into the drawbells. As ore is removed from the drawbells the orebody caves in, providing a steady stream of ore.<ref name="Underground Drilling and Loading Handbook"/> If caving stops and removal of ore from the drawbells continues, a large void may form, resulting in the potential for a sudden and massive collapse and potentially catastrophic [[windblast]] throughout the mine.<ref>{{Cite web | first1 = J. C. W. | last1 = Fowler | first2 = B. K. | last2 = Hebblewhite | title = Mining publication | year = 2003 | location = New South Wales | url = http://www.mining.unsw.edu.au/Publications/publications_staff/Paper_Fowler_AGCM_2003.pdf | access-date = 2007-05-30 | archive-date = 2006-09-20 | archive-url = https://web.archive.org/web/20060920043418/http://www.mining.unsw.edu.au/Publications/publications_staff/Paper_Fowler_AGCM_2003.pdf | url-status = live }}</ref>{{Better source needed|reason=Not verified on the website|date=February 2019}} Where caving does continue, the ground surface may collapse into a surface depression such as those at the [[Climax mine|Climax]] and [[Henderson molybdenum mine]]s in [[Colorado]]. Such a configuration is one of several to which miners apply the term "glory hole". Orebodies that do not cave readily are sometimes preconditioned by [[hydraulic fracturing]], blasting, or by a combination of both. Hydraulic fracturing has been applied to preconditioning strong roof rock over coal [[Longwall mining|longwall]] panels, and to inducing caving in both coal and hard rock mines. *'''[[Room and pillar]]''' : Room and pillar mining is commonly done in flat or gently dipping bedded ore bodies. 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 stope access, allowing the roof to collapse and fill in the stope. This allows for greater recovery as less ore is left behind in pillars. *'''[[Sublevel caving]]'''<ref>Sjöberg, J., F. Perman, D. Lope Álvarez, B-M. Stöckel, K. Mäkitaavola, E. Storvall and T. Lavoie. "Deep sublevel cave mining and surface influence", in: ''Deep Mining 2017: Eighth International Conference on Deep and High Stress Mining'' (Perth, March 28–30, 2018). Wesseloo, J. (ed.), pp. 357 –372. Perth: Australian Centre for Geomechanics, Perth, ISBN 978-0-9924810-6-3, 2017.</ref> *'''[[Raise caving]]''' : This is a method designed for high-angle orebodies at depth where regional stresseses are high. In raise caving the rock masses are de-stressed by establishing slots parallel to the dip of the orebody.<ref>{{Cite journal |title=Raise Caving—A Hybrid Mining Method Addressing Current Deep Cave Mining Challenges |journal=BHM Berg- und Hüttenmännische Monatshefte |last1=Ladinig |first1=Tobias |volume=167 |pages=177–186 |last2=Wagner |first2=Horst |last3=Karlsson |first3=Wimmer |last4=Grynienko |first4=Michal |year=2022|issue=4 |doi=10.1007/s00501-022-01217-3 |bibcode=2022BHM...167..177L |doi-access=free }}</ref> It is a new method under development by [[LKAB]] in [[northern Sweden]].<ref>{{Cite news |title=LKAB utvecklar ny brytningsmetod – så går metoden raise caving till |url=https://www.svt.se/nyheter/lokalt/norrbotten/brytningsmetoden-raise-caving |date=2021-06-08 |access-date=2024-06-21 |work=[[Sveriges Television|SVT]] |language=Swedish}}</ref>
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