There are many factors that cause dilution in underground stoping operations as illustrated in the following figure.

The factors affecting the mining method, performance and backfill reliability can be controlled as they are functions of the mining system and the resulting dilution can be estimated or planned.

However dilution due to ground conditions is difficult to predict and results in unplanned dilution.

Dempers & Seymour has developed the Dilution Rating System (DRS) that takes cognisance of the rock mass properties to allow estimation of dilution thickness.

The geotechnical properties that affect dilution are unique to each mine site. These parameters are estimated in the MRMM and include:

  • Rock strength
  • Joint orientation
  • Shear strength
  • Fracture frequency
  • Joint roughness
  • Induced stress
  • Joint infill
  • RQD

Using the relevant block values from the MRMM, the DRS is calculated and calibrated for each mine site to develop a design chart that is then used to predict dilution thickness.

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090216 - 4040S P3 Stope

Dilution Rating System