“When it comes to underground mining, there are different ways to approach removing coal, depending its structure and location. “Room and pillar is a non-subsidence plan for a mine, preserving the precious farmland above. It is among the safest and one of the most ecologically-friendly approaches to mining coal today, creating a non-subsidence environment (no movement of land) and maintaining clean water standards.
“As the name indicates, large pillars of coal (40 feet wide) are left standing to help support the roof of the mine—more than half of the coal remains intact as supporting pillars to maintain the integrity of the surface land. The end result is a grid of open space (rooms) cleared by a continuous miner machine and separated by pillars. Once the coal is cleared and placed on a conveyor belt, roof bolters enter the new area to secure the roof, inserting fully grouted 6-foot metal rods every four feet.”
(1:38/2014 / Sunrise Coal)