Borehole Radar

Report
APPLICATION OF BOREHOLE RADAR TO
POTHOLE IDENTIFICATION AND
DELINEATION AHEAD OF THE WORKING
FACE IN PLATINUM MINES
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
4th International Platinum Conference: Platinum In Transition ‘Boom or Bust’
11th – 14th October 2010, Sun City, South Africa
Outline
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Introduction
Efficient
 Instrumentation
 Deployment Methods
Effective
 Borehole Radar Survey Design
 Results and Interpretation
Economic
 Financial Implications
Conclusions
Introduction
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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
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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.
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Probe diameter: 32 mm
Length 1.65 m
BHR Profiling at ~10 m/min
Omni directional antenna
Efficient: Deployment
t
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
Radar deployment
Radargram
Efficient: Borehole radar process
Radar survey
Radargram
Report & Surface
Geology info
Directional survey
Database
Interpretation
Thin seam Platinum Mining
BHR for Platinum Mining
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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
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Why Borehole Radar?
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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
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Thin seam Platinum Mining
Reef thinning <50cm
Potholes
Effective: Thin seam Platinum Mining
Effective: BHR Survey Layout
Effective: BHR Surface Generation
RADAR SURFACE
Effective: Survey Layout
Effective: Borehole Design
± 10m
Anorthosite
PxA
Feldspathic Pyroxenite
± 7m
Triplets ~0.3m
Leader Seam ~0.2m
Main Seam (UG2) ~0.7m
Pegmatoidal Feldspathic Pyroxenite ~0.6m
± 5m
± 25m
± 4m
Mela- to Leuconorite
(BLESKOP MARKER)
Pegmatoidal Feldspathic Pyroxenite ~0.9m
Anorthosite ~0.9m
Leuconorite
8mm Cr. Stringer
Feldspathic Pyroxenite ~4m
UG1 ~0.1 – 1m
± 5m
Anorthosite
Effective: All Five Radargrams
Effective: Section
Effective: Interpretation
Example
Example: Conclusion
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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…………
UG2 COLLAPSE INTO
UG2 SHEARS & DROPS
~ 15m POTHOLE
PULLING PxA ~2M
RADIAL DISTANCE FROM BOREHOLE (m)
UG1
Bleskop
Marker
UG2
PxA
UG2 HANGING WALL
PxA BREAK-AWAY
DISTANCE FROM COLLAR (m)
Economic: Financial Implications
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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$1M in unnecessary
development in panels that
contain un-mineable reef.
Economic: Financial Implications
Financial impact summarised (after Du Pisani, 2008)
Item
Extent
Tonnes
Cost
Avoidable
mining
4300m2
14,400
US$ 1.03m
Avoidable
development
338m
Total
US$ 0.23m
US$1.26m
Economic: Financial Implications
Impact of reduced dilution:
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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):
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A 50 hole a year Self-Drive BHR program will cost:
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
A 1% reduction in waste because of geological certainty will
pay for BHR!
Advantages of using BHR in Platinum
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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
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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:
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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

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