ExplorMine Consultants has been commisioned by various clients to manage and supervise Tailings Storage Facility (TSF) drilling and sampling programmes, as well as complete Mineral Resource estimations for these TSF’s.
An auger drilling technique is utilised to drill the TSF’s due to the relative ease and low cost of the method. In addition, the TSF material is well suited to the method. The drilling contractor generally utilises a custom built auger drill powered by a portable diesel motor with generator which provides power for a basic set of hydraulics, the drill string and the spiral and provides a brake and a lifting mechanism. A base plate (box), which contains the brake and lifting mechanism, is generally sunk 20 cm to 30 cm into the TSF surface so as to anchor the unit.
Samples are drilled in 1.5 m increments using a 4.2 m barrel which contains a spiral which rotates and moves the sample material up the sample barrel from the bit face.
As each sample barrel is hauled to surface and placed on a set of trestles, one of which has a pipe clamp attached. The spiral is removed from the sample barrel and the sample falls into a sample bag/container. The procedure includes removing all sample material from the spiral, which is washed in a plastic tube containing water. Before reinserting the cleaned spiral in the sample barrel, the barrel is cleaned with a wet cloth to ensure no sample material remains as a contaminant of the next sample.
The estimation process typically employes several estimation techniques for estimate appropriateness testing, as well as cross validation between different estimation techniques. These techniques are namely:
- Inverse Distance to the Power 2 (“IDP2”);
- Arithmetic mean (“AVG”); and
- Nearest neighbour (“NN”).