APPLICATION OF BOREHOLE RADAR TO POTHOLE IDENTIFICATION AND DELINEATION AHEAD OF THE WORKING FACE IN PLATINUM MINES

4th International Platinum Conference: Platinum In Transition ‘Boom or Bust’

11th – 14th 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

tEfficient: DeploymentThe 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 holeSignal is sent radially outwards into the surrounding rockThe 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

Radargram Report & 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 ToolRemoving 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 ROCKBOREHOLES

RAISE

HAULAGE

CROSS CUT

Effective: BHR Survey Layout

HOST ROCKBOREHOLES

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) ~0.7mPegmatoidal Feldspathic Pyroxenite ~0.6m

Mela- to Leuconorite(BLESKOP MARKER)Pegmatoidal Feldspathic Pyroxenite ~0.9mAnorthosite ~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 & DROPSPULLING PxA ~2M

RADI

AL D

ISTA

NCE

FRO

M B

ORE

HOLE

(m) UG1

BleskopMarker

UG2

PxA

UG2 COLLAPSE INTO~ 15m POTHOLE

UG2 HANGING WALLPxA 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

Item Extent Tonnes Cost

Avoidable mining

4300m2 14,400 US$ 1.03m

Avoidable development

338m US$ 0.23m

Total US$1.26m

Financial impact summarised (after Du Pisani, 2008)

Economic: Financial ImplicationsImpact 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 ImplicationsImpact 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