Retreat mining is the removal of pillars in the underground mining technique known as room and pillar mining.
In the first phase of room and pillar mining, tunnels are advanced into the coal or ore body in a rectangular pattern resembling city streets. Pillars are left between tunnels to support the weight of the overburden. The first phase is known as "mining on the advance," from the entrance toward the further reaches of the reserve.
In the second phase, once advance mining has been completed, pillars are removed "on the retreat." Removing or "pulling" pillars begins far from the entrance and proceeds toward the entrance. As the pillars are removed, the mine collapses because nothing remains to support the roof and overburden. Removing pillars causes stresses within the mine to shift and must be planned and executed carefully to reduce danger to miners and control the amount of stress exerted on remaining pillars and the mine floor.
Tunnels only make up about 15% of the reserve, so during advance mining, only about 15% of the coal or ore is removed. During retreat mining, an additional 75% of coal or ore may be removed because pillars make up much more of the reserve, bringing the total recovery of the resource to as much as 90%.
Retreat mining is a particularly dangerous form of mining: according to the Mine Safety and Health Administration (MSHA), pillar recovery mining has been historically responsible for 25% of American coal mining deaths caused by failures of the roof or walls, even though it represents only 10% of the coal mining industry.[1]
Retreat mining was being used at the Crandall Canyon Mine where a collapse in August 2007 trapped six miners.[2]
^Mark, Chris (2010). "Deep Cover Pillar Recovery in the US" (PDF). Retrieved 13 July 2012. {{cite journal}}: Cite journal requires |journal= (help)
^Borenstein, Seth (August 6, 2007). "Deadly Mining Method Often Used". The Washington Post. Associated Press.
Retreatmining is the removal of pillars in the underground mining technique known as room and pillar mining. In the first phase of room and pillar mining...
not required. Retreatmining (below) is an example of a process like this. Retreatmining is often the final stage of room and pillar mining. Once a deposit...
economics, a supplementary version of room and pillar mining, termed second mining or retreatmining, is commonly started. Miners remove the coal in the...
Room and pillar mining often leads to retreatmining, in which supporting pillars are removed as miners retreat, allowing the room to cave in, thereby...
can be classified as a form of retreatmining. Gate roads are driven to the back of each panel before longwall mining begins. The gate road along one...
retreat of the government of Republic of China to Taiwan (Chinese: 中華民國政府遷臺), also known as the Kuomintang's retreat to Taiwan or the Great Retreat (Chinese:...
and are even more common in mines that do retreatmining, in which the pillars are removed as the miners retreat towards the mine entrance with the intent...
underground, leaving a hole called a stope Room and pillar Longwall miningRetreatmining Fire-setting, a method used in stoping by setting fires to timber...
The explosion occurred during pillar removal conducted as part of retreatmining. Under Consolidation Coal Company ownership, coal production in 1977...
offerings and shut down mining. Many Chinese miners have since relocated to Canada and Texas. One company is operating data centers for mining operations at Canadian...
Mining maquis (French: maquis minier) is a type of shrubland biome. It forms on ultramafic rock as a result of forest cover retreat due to repeated wildfires...
Copper mining in the Democratic Republic of the Congo (French: Extraction du cuivre en République démocratique du Congo) mainly takes place in the Copper...
(64 km) of roadway. The colliery was one of the first NCB pits to deploy retreatmining, whereby roadways were driven to the limit of the coal reserves, and...
In the United States, copper mining has been a major industry since the rise of the northern Michigan copper district in the 1840s. In 2017, the US produced...
land use, waste management, water and air pollution, caused by the coal mining, processing and the use of its products. In addition to atmospheric pollution...
country's primary energy consumption. Poland is the second-largest coal-mining country in Europe, after Germany, and the ninth-largest coal producer in...
below the surface. Mining techniques there had been changed 20 years before the 1958 bump, from "room and pillar" to "long wall retreating" after reports...
firm after Chapter 11 recast". "West Virginia mine was doing risky retreatmining". San Diego Tribune. Retrieved 2017-09-19. Conlon, Kevin (12 February...
water, and the retreat of Andean glaciers. The effects of glacier retreat are different at the initial and final stages of glacier retreat—initially more...
mini-series. During season 1, the series was named Gold Rush: Alaska, and the mining occurred at Porcupine Creek, on the Alaskan panhandle. For season 2, the...