| Auger mining is a method for recovering coal by boring into a coal seam at the base of strata exposed by excavation. Normally one of the lowest-cost techniques of mining, it is limited to horizontal or slightly pitched seams that have been exposed by geologic erosion. Augering is usually associated with contour strip-mining, recovering coal for a limited depth beyond the point where stripping becomes uneconomical because the seam of coal lies so far beneath the surface. An auger removes coal by drilling or cutting horizontally into the coal seam. These machines bring the coal to the surface for stockpiling or haulage. Augers can reach depths up to 1000 feet into the mountainside. |