Laser Scanning at Mogalakwena Platinum Mine-South Africa

1. Laser Scanning at Mogalakwena Platinum Mine-South Africa Presented by David van Rensburg Geotechnical Department Mogalakwena Platinum Mine AngloAmerican PLATINUM Geospatial World Forum 18-21 January 2011

2. CONTENTS • Overview, Mogalakwena Platinum Mine Regional Locality • Mining Environment • Riegl LPM321 Laser Deployment • Slope Monitoring strategy used at Mogalakwena Mine • The 6th Dec 2009 bench failure event • Conclusions

3. Mogalakwena Platinum Mine-Regional Locality 3

4. Mining Environment Brittle hard rock, highly jointed, toppling failure 4

5. Riegl LPM321 Laser Deployment Riegl control point Blast shelter High transmissivity glass 5

6. Mogalakwena Platinum Mine the first open pit in the world to use lasers for slope stability monitoring. Fully automated system developed in 2005. Forms part of an integrated risk monitoring system, used mainly to determine long term slope deformation trends and to identify high risk areas. Scanning locations determined by the mine Geotechnical Department. Manual mode medium range profiling of surfaces, at distances up to 600m, although designed to operate up to distances of 6 000m at accuracy of 20mm. Scanning of highwalls done during daylight hours only because of security concerns. Riegl LPM321 Laser Deployment 6

7. Evacuation initiated automatically, without human intervention Must have human intervention to initiate evacuation Management Control GeoMoS RieglLaser Special Areas CommitteeManagement of Potentially Unstable Areas Safety Critical Monitoring Routine daily functions Photo- grammetry Identification of Critically Unstable Areas GroundProbe SSR Extensometer Daily VisualInspections Pit Alarms Detailed Inspections EvacuationProcedures Specialised technicalinvestigations Slope Monitoring strategy used at Mogalakwena Mine 7

8. Localised bench failure (700 tonnes) occurred on 6th Dec 2009, failure mode was Toppling failure. Initial slope movement (30m to the south of the failure) identified by the laser 3rd week in November. Slope stability radar deployed immediately. The 6th Dec 2009 bench failure event 8

9. Scanning data East Highwall,recording of the 6th Dec 2009 failure event, screen shot acquired 15th February 2010 9

10. Scanning data East Highwall,recording of the 6th Dec 2009 failure event, screen shot acquired 5th Dec 2009 10

11. Scanning data East Highwall,recording of the 6th Dec 2009 failure event, sharp deviation in the graph shows the failure event 11

12. Although the laser did not locate any movement in the failure area, it identified the precursor to the event almost a month earlier. Slope stability radar was able to provide 20 hour warning of the failure event, personnel were timeously evacuated. The integration of laser together with slope stability radar provides an effective and appropriate risk management system. The reputational and economic cost to any mining organization when personnel are injured or killed or equipment damaged or destroyed, are immense. The Riegl laser system plays a vital role in Mogalakwena’s approach to open pit risk management. Conclusions 12

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