Mining Coal

Coal mining techniques can be put loosely into three categories:

  1. strip or opencast mining
  2. underground mining
  3. auger mining
The area of coal available, the thickness and inclination of the seam, the value of surface land and other economic factors determine the technique used. In the United States, for example, approximately seventy percent of coal is mined using underground methods, almost thirty percent by strip mining and only about one percent by augering.