- Retreat mining
Retreat mining is a term used to reference the final phase of an underground
mining technique known asroom and pillar mining. This involves excavating a room or chamber while leaving behind pillars of material for support. This excavation is carried out in a pattern advancing away from the entrance of a mine. Once a deposit has been exhausted using this method, the pillars that were left behind initially are removed, or 'pulled', retreating back towards the mine's entrance. After the pillars are removed, the roof (or back) is allowed to collapse behind the mining area. Pillar removal must occur in a very precise order in order to reduce the risks to workers, due to the high stresses placed on the remaining pillars by the abutment stresses of the caving ground.Retreat mining is the term commonly referred to as the mining method employed by the
Crandall Canyon Mine and is believed, by some, to be a factor in the August 2007 collapse which trapped six miners. On November 21, 2007, the mine was sealed, entombing the deceased miners. The bureau of land management says retreat mining was being used.Robert E. Murray , CEO of Murray Energy (owner of the mine) says the technique was not being used at Crandall Canyon. [cite news
first=Seth
last=Borenstein
coauthors= Talhelm, Jennifer; Vergakis, Brock
title=Deadly Mining Method Often Used
url=http://www.washingtonpost.com/wp-dyn/content/article/2007/08/06/AR2007080601257.html
work=The Washington Post
publisher=The Associated Press
date=August 6, 2007
accessdate=2007-08-07 ]ee also
*
Longwall mining References
External links
* [http://amp.wpcamr.org/archives/97 "Retreat Mining" "Abandoned Mine Posts." Western Pennsylvania Coalition for Abandoned Mine Reclamation.]
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