Methods of Underground Coal Mining

Early Longwall Method

Before 1960, longwall mining advanced in multiple directions from a central shaft. Large pillars of coal were left around the shaft, but all coal was removed beyond these pillars. Miners placed rock and wooden props and cribs in the mined-out areas to support the mine roof. The overlying rock gradually settled onto these supports, thus producing subsidence at the surface. (The width of the above illustration is about 1000 feet.)
[ Illinois | DNR | OMM | LRD | Updated 20000907 ]