The geostatistical Discrete Gaussian (DG) model is demonstrated to be
capable of providing an effective means of implementing change of
support for Enterprise-style mineralisation and thus providing reliable
global recoverable resource estimates. At Enterprise, sample grade distribution proves to be highly positively
skewed, therefore significant deskewing of the histogram and reduction of
variance occurs when going from sample to block support. The DG model was experimentally tested in'the Southern Primary
Zone (SPZ) at Enterprise, where high anisotropy ratios and pronounced
short range structures are observed in variograms. The experimental test
was run for a change of support for which the variance reduction was.
approximately 60 per cent. This reduction is similar to that predicted by
Krige's Relationship ('the volume-variance relationship') for the practical
situation of a change of support from 5 m vertical blasthole samples to
3 m x 8 m x 5 m selective mining unit (SMU) blocks. The DG model was found to correctly predict the grade tonnage
relationships for a wide range of cut off grades. The experimental test
indicated that, given a representative histogram and variogram, the DG
change of support provides a computationally efficient and practical
means of reliably assessing global mineable resources at the early stages
of a mining project. Further, it allows a range of selectivity strategies to
be meaningfully and comparatively considered prior to mining.