What is mining of retreat?
retreat mining is the last phase of common coal mining techniques referred to as room and pillar mining. In the room and pillars of mining machine known as the "continuous miner" bored the network of chambers or "rooms" to the coal seam and leaves a non -existent pillar of coal in every room to support the roof of the mine. The mining of the room and the column proceeds inside, far from the entrance of the mine. When the coal seam expires or the real estate line is reached, mining of retreat is a process that acquires support coal columns and works from the rear of the mine towards the entrance, hence the word "retreat".
The mining of room and columns leaves approximately 57% of the coal for support. This represents a strong financial incentive for retreat mining as a way to get more material and maximize profits. The mining of retreat is a dangerous operation, which, however, is governed by strict safety regulations.
When pulling support columns, several techniques are used to the coast of mining ceilings and prevent the roof from falling. The mobile roof supportsReduce pressure to adjacent columns during this precisely performed mining phase. In some cases, wooden cots or hydraulic connectors are secured in place. Working from the back of the mine towards the entrance of the roof is expected due to the mining of retreat, although they should already be mined and released by collapsed portions.
One of the dangers associated with mining is coal explosions. As stabilizing columns are removed, the pressure on the walls and the remaining columns increases. In the same way, the stick will be sufficient pressure, the pressure can intensify to the extent that the wall explodes or bursts column, shoots the material into the mine. The result can be fatal for nearby miners and can be complicated by localized roof falls. The massive collapse of the column can also cause a domino effect on neighboring pills causing catastrophic failure.
mining of retreat came to the forefront of the reports in August 2007, when six miners became imprisoned in the Crandall Canyon mine in Utah. The miners were imprisoned in the back of the mine 6. August in a collapse that created a seismic reading of 3.9 to 4.0 recorded to Nevada. He appeared ten days later, killed three and injured six. The original miners were never found and rescue operations were dismissed for security concerns. Although mining of retreat was carried out in parts of the mine, co -owner Robert E. Murray publicly stated that it was not possible at the time of the collapse.
In the United States, it is responsible for the regulation of mining operations, including mining of retreat, including retreat mining. Research is underway to improve the safety of the mines.