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11th International Symposium on Rock Fragmentation by Blasting
Sydney, Australia, August 24th 2015
By Daniel Roy, Eng.
Underground Stope Drill and Blast
Designs Optimization Program
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Goldcorp | Éléonore site
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Goldcorp | Éléonore site environment
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© Goldcorp
Décapage Roberto, Juin 2014
‘Amphibolite facies gold mineralization: An example from the Roberto deposit’ Jean-François Ravenelle, doctoral thesis, December 3, 2012, Quebec City
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© Goldcorp
Éléonore gold mine project exploitation started in 2014
Commercial production declared on April 1, 2015
Daily tonnage of 3000 - 4200 metric tons is planned until 2017
The mine should reach its planned peak of production of approximately
7000 metric tons per day in the first half of 2018
Preliminary evaluations were done on stopes of greater dimensions
This study was one of the first initiatives taken on stopes that do not
exceed 3 meters in width
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Goldcorp | Éléonore project description
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T E X T L I N E 2
Horizon 1
Horizon 2
Horizon 3
Horizon 4
230mLv
650mLv
440mLv
800mLv
Decline 887mLv (Mar. 31, 2015)
Production Shaft 1145mLv (Mar. 31, 2015)
Exploration Shaft
Goldcorp | Éléonore production zones
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The easiest way to mine valuable ore bodies is through the use of
explosives and well-planned blasting layouts that produce
fragmentation profiles specifically designed for conveyance
equipment in underground mines.
The design of blasting patterns is specific to not only the
explosives that are being used, but also to the rock or ore type
that is being fragmented.
The primary technical objective of this paper is to outline a unique
methodology for determining underground blasting methodologies
(developing specific blasting parameters) commensurate with
explosive energies and rock/ore equations of state for a narrow
vein gold property located in Northern Quebec and underground
mines in general.
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Abstract
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Blast design software Break parameter views
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The procedures developed are to define the desired fragmentation
specification
Specific thermodynamic break, taking into account:
- powder factor
- energy factor
- tonnages
- explosive energies distribution
- blasthole diameter
- orebody orientation
- specific type of explosive and dynamic rock/ore properties
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Blast design methodology
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Dynamic rock/ore properties:
- Determining dynamic modulus values for the ore using seismic sensors to measure P and S wave velocities,
- Parameters will be used to set the design constraints to maximize recovery and to minimize overbreak and dilution.
New underground blasting software (AEGIS/i-Ring) will use a
thermodynamic break in conjunction with defined fragmentation profiles
to create an array of blasting parameters used to design and plan ring
layouts.
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Blast design methodology
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Narrow vein design | All bulk emulsion loads
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Optimal loading scenarios | Products mix
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North East view
Top view
Type of rock Rcompressive
(Mpa)
Rtensile
(Mpa)
Young’s
Modulus (Gpa)
Poisson
ratio
Density
(m.t./m3)
Mineralized
wacke (ore) 122.0 17.0* 42.63 0.16 2.74
Wacke
(Waste) 162.0
15.0*
39.05 0.14 2.75
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Mine rock properties
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* These values Rtensile were used in the estimation
of the design break of each explosives types.
General Rock Classification - 1 Local Properties - 4
Rock Name : ORE ELEONORE Static Compressive Strength (Mpa) 121.97
TYPE METAMORPHIC ID : 215 Dynamic Compressive Strength (Mpa) 152.46
Location NW QUEBEC Static Tensile Strength (Mpa) 6.16
Source GOLDGORP ELEONORE MINE Dynamic Tensile Strength (Mpa) 7.7
Global Properties - 2 In-Situ Compressive Rating (Mpa) 121.97
Youngs Modulus (Gpa) 42.63 In-Situ Tensile Rating (Mpa) 6.16
Poisson Ratio 0.16 General Structure and In-Situ Geology - 3
Rock Density (kg/m3) 2739.63 Join Sets THREE JOINT SETS 50
Fracture Index (%) 25.3 Geology 1000
P-Wave Velocity (m/s) 4098.70 Q (10 - 100) 80 JRC (10-100) 80
S-Wave Velocity (m/s) 2607.63 RMR (10 - 100) LOW 60 HIGH 80
Shear Modulus (Gpa) 18.38
Bulk Modulus (Gpa) 20.89
Crack Velocity (m/s) 1206.07
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Ore rock parameters
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Standard Break Parameters
Dynamic Values Sensitivity on Break -30% -15% Mean 15% 30%
In-Situ Tensile Rating (MPa) 4.31 5.23 6.16 7.08 8.01
In-Situ Compressive Rating (MPa) 85.37 103.67 121.97 140.26 158.56
Borehole Pressure (MPa) 5036.26 5196.28 5361.38 5531.72 5707.48
Minimum Break (m) 2.33 2.21 2.12 2.05 2.00
Maximum Break (m) 5.08 4.68 4.38 4.15 3.97
BKO 45.000 SBR 1.140
J: Pattern Spacing (m) 2.45 2.36 2.30 2.24 2.20
K: Pattern Burden (m) 2.15 2.07 2.02 1.97 1.93
Tons Broken (Ton metric) 213.9 198.91 187.86 179.32 172.53
Powder Factor A for a full Explosives Column (kg/ton metric) 1.13 1.21 1.28 1.35 1.40
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Break radius simulation per charge types
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GOLDCORP Éléonore mine | Test bloc 1, Break Radius Simulations per charge types
Blast holes of 100mm over 30m Blast holes of 90mm over 30m
SUBTEK charge 100mm (fully coupled) SUBTEK charge 90mm (fully coupled)
0% overlap: 0% overlap: 15% overlap:
Rmin 10.28ft Rmin: 9.43 Rmin: 8.28
Rmax 22.19ft Rmax 24.50ft Rmax 20.82ft
Pattern: 14.4 x 16.4 Pattern: 13.08 x 15.36ft Pattern: 10.47 xx 12.29ft
25% overlap: 25% overlap:
Rmin: 8.27 Rmin: 7.60
Rmax 19.64ft Rmax 18.37ft
Pattern: 9.72 x 11.08ft Pattern: 8.87 x 10.41ft
35% overlap: 35% overlap:
Rmin 7.59 Rmin: 6.99
Rmax 13.02ft Rmax 15.92ft
Pattern: 8.09 x 9.23ft Pattern: 7.40 x 8.69 ft
45% overlap: 45% overlap:
Rmin 6.98 (2.13m) Rmin: 6.44
Rmax 14.40ft Rmax 13.47 ft
Pattern: 6.63 x 7.75ft (closest to mine pattern of 6.43 x 7.54ft) Pattern: 6.08 x 7.14 ft
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Bulk emulsion break results | 100mm vs 90mm charge
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Vibration limits review
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New maximum limits were defined from the monitoring program applied
over the last few months.
At the start of our study, a limit of 250mm/sec had been established,
based on readings made at some 30-40m distances from the stope
blasts.
Determination of the P wave value, made from our March 2015 trials,
allowed us to establish much better correlations between amplitude levels
measured at proximity to the stope hanging walls and permanent
damage criteria.
A P wave value of 6,414m/sec was obtained from our monitoring, while it
had initially been estimated to 4,099m/sec at the beginning of our work.
Observations | Vibration amplitude value limits
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PPV = Tdyn / Density x Pv
- Density : 2.74 m.t./m3
- Dynamic tensile strength: 17.0MPa
- P wave velocity: 6,414m/sec
According to the dynamic tensile strength determined, we get the
following window of values:
The indicated values represent the limit that should not be exceeded in
order to avoid incipient permanent damage to the wall structures.
Establishment of new vibration amplitude limits
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Some important exceedances in certain complex production blasts.
Blast no.3 of stope 440-0505-354 was a special case that needed more
attention to better understand muck flow mechanisms involved.
The stope configuration included two perpendicular portions, with:
- Trench including the slot being E-W, and
- Bulk portion of the tonnage along the N-S axis.
Initial phase was to open the E-W trench (rings 20 to 27) surrounding the
slot containing a 0.76m reamed hole.
Once this volume was fired, 2 groups of sections were attacked,
1) rings 7 to 19 were mainly shooting from S to N, while
2) rings 1 to 3 were going N to S.
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Vibration limit exceedances
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HF-01 & HF-02 geophone positions on level 410
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Two perpendicular stope portions
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N
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Increase of amplitude levels following progression of the blast firing sequence (HF-02)
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Scale distance value from 1 to 9
for regular long hole blasts.
≤ 250mm/sec: normal break
> 569mm/sec: ``X-Damage``
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Charter Limits PPV vs SD SD: 1 to 9
250mm/sec
Parameter PPV (mm/s)
Rock breakage 2540
Onset of rock
breakage 635
Rock falls in unlined
tunnel 306
Horizontal
displacement in loose
material
762
Weakening of
bulkheads
underground
457
Electric motor shaft
misalignment 254
Cracked plaster 50.8
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Impact of high vibration amplitude on hanging wall
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Cylindrical shock wave in
expansion
Scale distance formula
SD: D / W1/2
SD values from 1 to 9 for regular
long hole blasts
We use equivalent cylinder
dimensions to show the break
of various types of explosive
charges.
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Underground seismic measures for cylindrical charges where L/D > 6:1
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Different geometries to define break and powder factor in mining
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More suitable to underground ring blasting Suitable to surface mining
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Drill pattern adjustments based on overlap ratio (%)
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Established break radius for each explosive product, using
the mineralized rock parameter values that were supplied
Updated once we completed our in-situ field measurements
P wave measurements to revise the equivalent break radius
New comparisons were made between:
- Usual drill patterns
- Those the mine was envisioning to apply using 0.1m hole diameter (2.0m x 2.3m).
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Break radius calculation for various explosives
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Typical radial fractures in blast fragments
High shock energy Low shock energy
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Maximum break
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Distance that
a certain percentage of
cracks can reach
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% overlap between cylindrical envelops
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% overlap, Rmin, Rmax, R equivalent break cylinder,
dictate level of fragmentation, ± coarse
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Ore geomechanical parameters in 2014
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4099 m/s =
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Ore geomechanical parameters measured in 2015
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6199 m/s =
2014 values
New values from 2015 (increase of 3.7%)
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Design breaks per product types
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# 0 25 35 45
Design Break
10.28pi. / 3.13m 8.27pi. / 2.52m 7.59pi. / 2.31m 6.98pi. / 2.13m
Rmin:2.13m
Pattern
(pi./m)
14.4 x 16.4 pi.
4.39 x 5.0m
9.72 x11.08 pi.
2.96 x 3.38m
8.09 x 9.23 pi.
2.47 x 2.81m
6.63 x7.75 pi.
2.00 x 2.30m
% OVERLAP 0 25 35 45 51
Design Break
10.68pi./3.26m 8.58pi./2.62m 7.87pi./2.40m 7.23pi./2.20m
Rmin: 2,21m 6.88pi./2.10m
Pattern (pi./m) 15.73 x 17.93
4.80 x 5.47m
10.83 x 12.35
3.30 x 3.77m
9.06 x10.33pi.
2.76 x 3.15m
7.44 x 8.48 pi.
2.27 x 2.59m
6.54 x 7.45pi
2.00 x 2.30m
Increase of 3.7% of the design break for the same 0.1m SUBTEK
charge (Rmin goes from 2.13m to 2.21m)
Consequences:
- Significant increase in the powder factor
- Increased risk of detrimental charge interaction (dead-press)
- Tolerable deviation percentage has to be significantly reduced
- Potential for detonation velocity reduction because of high charge concentration in certain areas of the panels
- Possibility of bulk emulsion desensitization (lower VOD, more toxic fumes, more large boulders in draw points)
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Design break calculation per product types
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High % overlap between charges | Consequences
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Desensitization
Block of 0.6m
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Observations | Waste chunks of 0.6m thick
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Similar big blocks coming from the damage to the
hanging walll done by the radial cracks.
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Firing Sequences
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Firing delay methodology based on the equation of dynamic movement
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Delay determination using burden velocity (Gv) and the desired % of burden moved (n): 2-3 holes/section, large stope, depth of 32.0m
Length of charge: 30.0m (100pi)
Velocity of detonation: 5,488m/sec (18,000
pi./sec)
Spacing: 2.3m (7.54pi.)
Burden: 2.0m (6.57pi)
P-wave velocity: 6,414,/sec (21,038pi./sec)
S-wave velocity: 2,608m/sec (8,555pi./sec)
Crack propagation velocity: 1,206m/sec
(3,956pi./sec)
Gv: burden movement velocity
% advance of burden: n= 0.3, 0.6, 0.8, 1.0
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Pattern of 2.0m x 2.3m: large stope
Timing options:
• Inter-hole delay = 15ms/hole
• Possible inter-row delays of 44ms, 52ms, 61ms, 74ms, 114ms to 140ms
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Conclusion
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For the last 12 months, the Éléonore Mine engineering department and
several external experts have defined optimal blasting practices for their
continuously changing mining conditions.
- The vibration data collection program implemented in 2014 has delivered valuable benefits and will remain a key component of the program.
- Through the in-situ seismic waves measurement program, we were able characterize and quantify, with greater precision, the wave transmission mode in the rock mass they are presently mining.
- The challenges remain to customize stopes design that deliver the mineral value expected and planned to be fully recovered.
- Several blasting software tools were used to assist with the interpretation and visualization of the different types of monitoring that were performed.
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Conclusion
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Our key findings were:
- Limits that must be respected to avoid inducing permanent stope’s wall damage
- The vibration amplitude limit of a regular 200kg charge of bulk emulsion should not exceed 300mm/sec.
- Adjustments to electronic firing sequences as part of an on-going challenge as the mine is looking to reduce its number of blasts per stope.
- On going statistical data compilation and regression to define attenuation modes applicable to each future mining horizons at Éléonore.
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Conclusion
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Up coming tasks:
- Quantification of fragmentation generated by specific blasting scenarios will guide us in our approach.
- Modeling adjustments to firing sequences as a function of burden velocities through AEGIS/i-Ring
- Variable energy application along the stope wall limits will be investigated.
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Conclusion
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Typical results with an optimized design
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Typical CMS results with an optimized design
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Once applied…no excess of dilution
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Questions ?
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Thank You
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Daniel Roy, Eng. +1 450-464-2111, ext. 8581
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