coal ball rolling mill level measurement
Coal Ball Mill Level Measurement tasleek . A. Abutment 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 coal ead of the face and the back ...