Figure 10-2: Schematic of the Bauer desander and classifying plant
10.2.3 LDD DOWNHOLE CALIPER MEASUREMENTS
A downhole calliper survey was completed on each of the LDD holes by DGI. The LDD calliper surveys measure the diameter of the drillhole along its length and use those measurements to calculate the volume (in cubic metres) of material removed from the LDD hole. This calculation, coupled with diamond recovery data, is then used for estimating the sample grade for each of the LDD samples. The data were presented as a graphic 3-D downhole log and a downhole Excel spreadsheet.
Actual sample weights of material recovered from the drilling cannot be used for grade estimates because the material is screened after it exits the hole and fine material smaller than 0.85 mm is not collected. There is also loss of material to downhole fractures and joints. Therefore, this necessitates a theoretical estimation of sample volume using the calliper data and the density data measured on core from the pilot core holes.
Eggleston et al. (2008) recalculated the volumes of several holes and found the volumes provided by DGI to be accurately calculated and were of the opinion that the calliper surveys provide reliable hole diameters. P&E has not independently recalculated the volumes using the original survey data.
P&E Mining Consultants Inc. NI 43-101 Technical Report No 159 Shore Gold Inc. - Star Diamond Project Resource Estimate Update
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