room and pillar in a sentence

Examples

1. The salt is dug out by the room and pillar method, where about half the material is left in place to support the upper levels.
2. Approximately 200, 000 tons of coal were dug at Grand Lake between 1639 and 1887 using surface collection, vertical shafts and the room and pillar system.
3. However the latter may be easily confused with the collapse of old room and pillar coal mine workings which undoubtedly underlie the southern part of the town.
4. Room and pillar mining often leads to retreat mining, in which supporting pillars are removed as miners retreat, allowing the room to cave in, thereby loosening more ore.
5. Mine operators started using the " room and pillar method " _ carving the supporting pillars in a regular grid to allow space between them for roads and buildings.
6. In general practice, the size of both room and pillars are kept almost equal, while in Bord & Pillar, pillar size is much larger than bord ( gallery ).
7. No . 6 had a shaft, while No . 7 had a shaft . Both mines worked the same coal seam, using the double-entry room and pillar system of mining.
8. Mine out horizontal orebodies with ease using our room and pillar modelling module, from creating the 3D orebody model to picking out your pillar areas then calculating volume and tonnages.
9. Both mines were worked on the room and pillar system, with approximately height of extraction within the seams, leaving some ironstone for roof support ( c . 2.5m depth ) and roadway.
10. Where the seams are relatively flat lying or gently dipping most of the mines were underground room and pillar operations, and where the seams are steeply inclined to vertical, stope mining was used.