Single Trace Analysis Impact on Initiation Sequence Optimization for High Wall Control_AngloGold y Otros_Africa

7/25/2019 Single Trace Analysis Impact on Initiation Sequence Optimization for High Wall Control_AngloGold y Otros_Africa

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High Wall Control Using EDD at

Anglo Gold Ashanti, Navachab Mine

Single trace analysis impact on

initiation sequence optimizationfor high wall control


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Anglo Gold Ashanti, Navachab Mine


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Agenda

Introduction to Mine

The Challenge

The ApproachMeasuring Rock Response

Initiation System DeltadetsTiming Designs

Results

Conclusion


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Started June 1990

Farm Navachab

Initially - 840 000 tonsmined per annum

Currently - 1.3 milliontons mined per annum

Introduction to the Mine

WindhoekSwakopmund

Navachab Gold Mine


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1st Wall Failure - June1998, +- 15m high

2nd

Wall Failure -September 1999, +- 30mhigh

3rd

Wall Failure - March2001, +- 50m high

The Challenge

Failure


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Navachab Gold Mine

Failure


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Micro-Seismic System

Legend

Geophones

Failure


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Energy Release Rate

Energy Release Rate (KJ per Month)

0

50

100

150

1 2 3 4 5 6 7 8 9 10 11 12

Time (Months)

Cum

ulative

Energy

KJ

Slow Release Rate Fast Release Rate Sudden Release


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y = 1347.4x - 5E+07

-100

-50

0

50

100

150

200

250

300

Data Recorded over 8 Months

Cumula

tiveEne

rgy(Kj)

Conventional Blasting No Mining Linear (Conventional Blasting)

Micro-Seismic System

Energy Release Rate

????PPV = ?


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Bench Parameters

Bench Height 5m

Hole Depth 6m

Hole Diameter 115mm

3.4m x 3.4m

PF = 0.7

Charge Mass / Hole Avg. 40 Kg

12 Blasts Conducted during Trails


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Peak Particle Velocity

N

Failure

Seismograph

Seismograph

Block

65.1

1143

=

W

RPPV

R is the distance from the blastW is the charge mass per hole


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Manage risk

The Approach

Vibration Control

Optimise Design


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Rock Response Time

2 Drums Secured To High Wall

115mm Hole Charged 5m Bench; 3m Burden

Flash Activated when Hole Detonates Drum Movement Recorded with HighSpeed Camera

Time Calculated Between Flash andmovement of Drums

Rock Response Time ~ 4.1ms per m


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Rock Response Time

0.5

1

1.5

2

2.5

3

3.54

15 20 25 30 35 40

Time (ms)

Distance

(m)

Drum 1

Drum 2

9 - 12ms


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Measuring Rock Response


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Signature Trace Analysis

Hole 2Delay : 0 to 500 ms

Hole 1Delay : 0 ms r1

r2

Hole 1 Hole 2

Individual PPV : V

500 ms delay


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Measuring Signature Trace

-8

-4

0

4

8

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0

Time (ms)

Amplitude(mm/s)

Delay (ms)


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Optimal Delay Values

0

5

10

15

20

0 10 20 30 40 50 60 70

Delay Period (ms)

PeakAmplitude(mm/s)

9ms 60ms


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0

5

10

15

20

0 10 20 30 40 50 60 70

Delay Period (ms)

PeakAmplitude(mm/s)

7.5ms 10.5ms 49.8ms 70.2ms

Conventional Blasting


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0

5

10

15

20

0 10 20 30 40 50 60 70

Delay Period (ms)

PeakAmplitude(mm/s)

Blasting using EDDs

Minimal PPV Values Using EDDs


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Radiation from a hole

C

C = function of the rock type3000 - 6000 m/s

Ri k h i i


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Risks when using precise

detonators

Ri k h i i


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detonators



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detonators



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detonators



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detonators



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detonators



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detonators



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detonators



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detonators


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BlastMap Model

Allows the use of

The relative hole positions The speed of the seismic wave

Assumes Symmetric radiation

Ignores

Reflection and refraction

Timing Designs


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Constructive

N

Constructive

Timing Designs

Interference Patterns

Initiation System


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BlastingBlasting

BoxBox

Initiation System

EDD System

BaseBase

StationStationFieldField

terminalterminal

BlastMapBlastMap

softwaresoftware

Initiation System


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Initiation System

Wireless Blasting Contributing to SafetyManage Risk

Dets are Automatically Programmed,which reduces exposure to riskBlaster is out of pit when Blast is Initiated

Ti i D i


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Timing Designs

23m

s

60 ms


0

5

10

15

20

0 10 20 30 40 50 60 70

Delay Period (ms)

PeakAmplitude(mm/s)

9ms

60ms

0.5

1

1.5

2

2.5

3

3.5

4

15 20 25 30 35 40

Time (ms)

Distance(m)

Drum 1

Drum 2

Rock ResponseTime

Ti i D i


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Timing Designs

12m

s

60 ms


0

5

10

15

20

0 10 20 30 40 50 60 70

Delay Period (ms)

PeakAmplitude(mm/s)

9ms

60ms

0.5

1

1.5

2

2.5

3

3.5

4

15 20 25 30 35 40

Time (ms)

Distance(m)

Drum 1

Drum 2

Rock ResponseTime

Ti i D i


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Timing Designs

9ms

63 msOptimal Delay Values

0

5

10

15

20

0 10 20 30 40 50 60 70

Delay Period (ms)

PeakAmplitude(mm/

9ms

60ms

ConstructiveN

Constructi

0.5

1

1.5

2

2.5

3

3.5

4

15 20 25 30 35 40

Time (ms)

Distance(m)

Drum 1

Drum 2

Rock ResponseTime

Results


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Results

Ground VibrationPPV Recorded - EDD vs Pyro Blasts

0

20

40

60

Number of Blasts

PeakAmplitude(

mm/s)

EDD Blasts

Pyro Blasts

Timing

EDD 17x42 ms

Pyrotechnic -17x42 ms

Timing

EDD 23x60 ms


Timing

EDD 9x63 ms


R lt


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Results

Results


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Results

Ground Vibration

Dominant Frequency Range

0

40

80

120

Date

Fre

quency(H

z)

Dominant Frequency (Hz) Resonant Rock Frequency (Hz)

Results


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esu ts

Ground Vibration Pyro Blast

EDD Blast

Results


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y = 1347.4x - 5E+07

-100

-50

0

50

100

150

200

250

300

Data Recorded over 1 Year

CumulativeEnergy(Kj)

Conventional Blasting No Mining Linear (Conventional Blas ting)

Results

????PPV = ?



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N

Failure

Seismograph

Seismograph

Constructive

N

Constructive

Block

Failure

Results


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y = 1074.2x - 4E+07

y = 1347.4x - 5E+07

-100

-50

0

50

100

150

200

250

300

350


Cu

mulativeEnergy

(Kj)

Conventional Blasting # of Electronic Blasts No Mining

Electronic Blas ting Linear (Electronic Blas ting) Linear (Conventional Blas ting)

Results

-20%


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0.5

1

1.5

2

2.5

3

3.5

4

15 20 25 30 35 40

Time (ms)

Distance(m)

Drum 1

Drum 2

Rock Response TimeRock Response Time

Constructive

N

Constructive

BaseBase

StationStationFieldField

terminalterminal

BlastMapBlastMap

softwaresoftwareBlastingBlasting

BoxBox


0

5

10

15

20

0 10 20 30 40 50 60 70

Delay Period (ms)

PeakAmplitude

(mm/s)

9ms

60ms

Constructive

N

Constructive

y = 1074.2x - 4E+07

y = 1347.4x - 5E+07

-100

-50

0

50

100

150

200

250

300

350


Cum

ulativeEnerg

(Kj)

Conventional Blasting # of Electronic Blasts No Mining

Electronic Blas ting Linear (Electronic Blas ting) Linear (Conventional Blas ting)

Conclusion


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Conclusion

Purpose Manage Risk

Method Rock Response Time

Signature Trace Analysis

Wave Interference Modeling

Optimised Designs

EDD Blasting

Measuring

Database Results

Reduced PPV

Reduced Energy Release Rate ?

Wall Control BHP Billiton / Xstrata plcDouglas Coal Mine, South Africa


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Douglas Coal Mine, South Africa

Wall Control Rio TintoRossing Uranium Mine, Namibia


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oss g U a u e, a b a

Acknowledgements


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Anglo Gold Ashanti, Navachab Gold Mine ISEE Conference

References

SRK Consulting Engineers and Scientists

ISS International

Tony Rorke, BME Blasting Specialist

Acknowledgements

Documents

Single Trace Analysis Impact on Initiation Sequence Optimization for High Wall Control_AngloGold y Otros_Africa