Room & Pillar


Fire clay is difficult to remove at the preparation plant, resulting in some clay being left in the final product and some coal fines being lost with the rejected fire clay.

Controlling to the floor with RAS is most important because it is more difficult for an operator to see the position of the cutter at the floor than at the roof and also because the avoidance of fire clay is most beneficial.                  

A smoothly cut floor is also important.


The Rock Avoidance Gamma Detector Technology has been well proven on a continuous miner in Room and Pillar mining. The Detector being installed so that it is looking through the picks on the cutter is critical due to the speed of shearing and machine dynamics is critical to the best RAS performance.

The detector and armor is designed to be rugged so it can be mounted near the cutter drum, and sensitive enough to pick up the change in radiation between the radiation in the coal and in the fireclay.

Other benefits of utilizing the gamma detector:

  • Geosteering completes the shear down in a consistent manner, using a minimum of cutting time by quickly determining the location of floor
  • Geosteering speeds up the cutting of coal by stopping the cutter from entering the out-of-seam rock so that the time saved can be used to continue to cut in-seam coal.
  • Displays assist operator at the roof by informing the operator of the height of the cutter above the floor.
      • Less rock handling, more coal mined
      • Greatly reduced fire clay in raw product
      • Less wear on equipment
      • Smoother floor – easier shuttle car movement
      • Smoother floor – easier shield advance
      • Reduced training time for new operators
      • Operator can be located at a safer distance
      • Assists in meeting noise and dust exposure regulations
      • Mine proven and MSHA certified