South Africa region - Exploration drilling and expenditure
The current exploration strategy aims at matching the resource confidence level to the short, medium and long-term mine design and schedule. To this end, two distinct drilling programmes are utilised, namely:
- Grade control drilling (mine definition drilling): This method is utilised to provide high resolution resource model information for short-term excavation design. The diamond drilling programme aims at achieving a 30m x 30m grid to support long-hole stoping scheduled in the 12-month plan and a 60m x 60m grid covering a two-year mining window ahead of the destress working faces. The data generated is used for local scale facies determination, structural definition, stratigraphic modelling and assaying for resource estimation.
- Long inclined borehole (lib) drilling: This method is utilised to provide resource model information for medium to long-term development and stope excavation design. The LIB drilling programme provides information ahead of the face at a 300 metre grid and is integrated with the mine definition drilling to derive the Resource model. These boreholes are drilled flatter than the grade control drilling to enable the collection of data as far ahead of the face as practically possible. LIB drilling provides additional information for structural definition, stratigraphic modelling, facies determination and assaying for resource estimation. This drilling programme is focused on a two to 10-year mining window ahead of the current working faces.
On-lease metres drilled and expenditure for the 12-month period ended 31 December 2017 are summarised below. No surface drilling exploration was conducted during 2017.
In accordance with the SAMREC Code, South Deep maintains rigorous QA/QC protocols on all its resource definition programmes. It draws on industry leading practice for data acquisition and utilises accredited laboratories which are regularly reviewed both internally and externally. Analytical QA/QC is maintained and monitored through the submission of blanks, certified reference material and duplicates, plus umpire laboratory checks. The borehole database, which serves as the input to the geological modelling and estimation processes, was externally reviewed and validated during 2016 by industry subject matter experts.
| December 2017 | December 2016 | ||||||||
| Operation | Metres drilled |
ZAR (millions) |
US$ ( millions) |
Metres drilled |
ZAR (millions) |
US$ (millions) |
|||
| Grade control drilling | 6,724 | 20.93 | 1.69 | 4,906 | 18.18 | 1.24 | |||
| LIB drilling | 2,248 | 4.46 | 0.36 | 2,602 | 5.58 | 0.38 | |||
Only LIB drilling is classed as exploration drilling
| Plan view showing the LoM design footprint and current borehole intersections used in the ore body definition |
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| Section along the dip of the reef highlighting mine design and layout differences between CM and NoW |