Room and Pillar mining

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 a greater recovery as less ore is left behind in pillars.

Ramps (inclined tunnels) are excavated to connect the surface to the underground orebody. Drifts (horizontal tunnels) are excavated at different elevations to surround the orebody. Next, stopes (tunnels that have direct access to mining the ore) are mined to gain access to the ore. All tunnels are excavated by drilling and blasting. Jumbos are in charge of drilling the holes in the rocks and filling them with explosives. The loose rock, also called muck, is transported by either dump trucks or Load Haul Dump (LHD) vehicles back up to the surface for either waste disposal or processing. As mucking progresses, rooms (tunnels) are cut into the ore body. In order to provide safe roof support for mining, pillars of material around the rooms are left standing to hold up the rock ceiling above. Some parts of the mine roof can be particularly weak and fragile. In addition to pillar support, a jumbo is then brought back in for rock bolting of the roof to ensure safety. When all the ore in the stopes has been transported up to surface, some pillars can be removed, since they still have valuable mineral content, while some must be left standing to provide active support for the ceiling. In some room and pillar mines, pillars are all excavated as mining nears completion, to allow the natural collapse of the roof.