Tunneling Bucket Crushers

Tunneling bucket crushers samratbakerslossary of mining terms coal educationbutment in coal mining, 1 the weight of the rocks above a narrow roadway is transferred to the solid coal along the sides, which act as abutments of the arch of strata spanning the roadway and 2 the weight of the rocks over a longwall face is transferred to the front abutment, that is, the solid.