APPLICATION OF BOREHOLE RADAR TO POTHOLE IDENTIFICATION AND DELINEATION AHEAD OF THE WORKING FACE IN PLATINUM MINES 4 th International Platinum Conference: Platinum In Transition ‘Boom or Bust’ 11 th – 14 th October 2010, Sun City, South Africa SPEAKER: Charles Golding, CEO, GEOMOLE AUTHORS: Carina Kemp, Senior Geophysicist, GEOMOLE Petro Du Pisani, Manager in-Mine Geophysics, ANGLO TECHNICAL SERVICES Mduduzi Shoke, Geophysicist, GEOMOLE

Outline  Introduction  Efficient  Instrumentation  Deployment Methods  Effective  Borehole Radar Survey Design  Results and Interpretation  Economic  Financial Implications  Conclusions

Introduction  Borehole Radar (BHR) provides highly detailed, continuous ore body and structural delineation information for accurate resource definition and mine planning.  Borehole Radar has been delineating ore bodies for mine planning for over 10 years.  Improvements in technology over the last 3 years enable borehole radar to be deployed on the drill allowing for quick and easy surveying underground.

Efficient: Equipment GeoMole BHR  10 – 124 MHz Bandwidth  Resolution: less than1m  Range: up to 50m or more (depending on rock type) Note: Borehole Radar will not work for all rock types but works very well in the Norites and Anorthosites in the Bushveld.  Probe diameter: 32 mm  Length 1.65 m  BHR Profiling at ~10 m/min  Omni directional antenna

t Efficient: Deployment The borehole radar system can be deployed by winch or on the drill rods similar to a gyro survey Data is acquired continuously as the rods are pulled and the radar ascends the drill hole Signal is sent radially outwards into the surrounding rock The radar images the rock surrounding the drill hole. The radar is not directional. Neighboring drill holes and knowledge of stratigraphy aids interpretation. Final interpretation is produced.

Efficient: Forming a radargram Radargram Radar deployment

Efficient: Borehole radar process Radar survey Geology info Directional survey Interpretation RadargramReport & Surface Database

Thin seam Platinum Mining

BHR for Platinum Mining  Mine Planning: Removing uncertainty - DON’T develop blindly  Geo-technical information prior to development - shaft and raise planning  Mapping the extent and location of dilution zones before mining – knowing what to avoid or investigate further  Extending the life of the mine – greater confidence in resource estimation

Why Borehole Radar?  Tactical Mining Tool Removing uncertainty - DON’T mine blindly  Providing a means to “view” the space that lies ahead of the working face - mapping the extent of structures and uncertainties ahead of mining  Mapping complex deposits  Mapping man-made structures, e.g. old workings  Illuminating sources of physical instability to allow the miner to either anticipate or even avoid hazards altogether  Safety - locating potentially hazardous zones

Reef thinning <50cm Potholes Thin seam Platinum Mining

Effective: Thin seam Platinum Mining

HOST ROCK BOREHOLES RAISE HAULAGE CROSS CUT Effective: BHR Survey Layout

HOST ROCK BOREHOLES RADAR SURFACE RAISE HAULAGE CROSS CUT Effective: BHR Surface Generation

Effective: Survey Layout

Effective: Borehole Design Borehole ± 10m ± 5m ± 25m ± 4m ± 5m ± 7m Anorthosite PxA Feldspathic Pyroxenite Triplets ~0.3m Leader Seam ~0.2m Main Seam (UG2) ~0.7m Pegmatoidal Feldspathic Pyroxenite ~0.6m Mela- to Leuconorite (BLESKOP MARKER) Pegmatoidal Feldspathic Pyroxenite ~0.9m Anorthosite ~0.9m Leuconorite 8mm Cr. Stringer Feldspathic Pyroxenite ~4m UG1 ~0.1 – 1m Anorthosite

Effective: All Five Radargrams

Effective: Section

Effective: Interpretation

Example

Example: Conclusion  Fortunately no significant disruptions, other than a 2.2m pull down from a reef roll, were detected ahead of mining with the borehole radar for this panel. This meant that mining could continue with confidence. However…………

DISTANCE FROM COLLAR (m) UG2 SHEARS & DROPS PULLING PxA ~2M RADIAL DISTANCE FROM BOREHOLE (m) UG1 Bleskop Marker UG2 PxA UG2 COLLAPSE INTO ~ 15m POTHOLE UG2 HANGING WALL PxA BREAK-AWAY

Economic: Financial Implications  Borehole radar survey results which were the subject of a different paper (Du Pisani 2008) detected a significant reef roll in a nearby panel. The paper showed that borehole radar surveys ahead of mining could have saved over US$1M in unnecessary development in panels that contain un-mineable reef.

Economic: Financial Implications ItemExtentTonnesCost Avoidable mining 4300m 2 14,400US$ 1.03m Avoidable development 338mUS$ 0.23m TotalUS$1.26m Financial impact summarised (after Du Pisani, 2008)

Economic: Financial Implications Impact of reduced dilution:  An average mine mines (say) 2 million tonnes per annum  Assume on-mine costs of approximately US$62.8 per tonne; 2 million tonnes will therefore cost US$125.7m  Geological losses ranges from 5% to 30%  Every 1% reduction in waste mined will save US$1.26m. 5% - US$6.29  This is only the on-mine cost saving. There are significant additional costs incurred in processing waste.

Economic: Financial Implications Impact of reduced dilution (continued):  A 50 hole a year Self-Drive BHR program will cost:  A 1% reduction in waste because of geological certainty will pay for BHR! Borehole radar costs$ 186,000 Drilling costs at R600 per metre for 50 x 200metre holes$ 857,000 Additional staff/consultants$ 100,000 Total borehole radar costs per annum$ 1,143,000

Advantages of using BHR in Platinum  Intelligent development  Reduced dilution  Additional ore  More confidence in resource estimation – continuous ore body maps  Safety improvement; AND  It is inexpensive and easy to use

Conclusions  Borehole radar technology has come of age and provides a demonstrably efficient, effective and economic means of mining smarter.  Supply side constraints facing the platinum industry will be mitigated by being more efficient, BHR can help.  Successful implementation requires:  mine management to see BHR as an operational tool; and  a strong partnership between the supplier and the end user.

Acknowledgements The authors thank:  Anglo Platinum for allowing these results to be published and for their vision and support of the implementation of geophysical programs.  all the Rustenburg geologists, borehole radar surveyors and drilling contractor Rosond who have made these borehole radar surveys possible.  the mine staff of Anglo Platinum for their professional enthusiasm which made this study both possible and enjoyable. The authors gratefully acknowledge the scientific and technical contributions of the borehole radar research teams at:  The University of Sydney  The University of Stellenbosch  CRCMining