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Blasting Masterclass 30 September 2014
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WealthUnearthed
Dimensioning explosives energy in the blast30th October 2014
What is an explosive?
Anthracite
Subbituminous
Lignite
Bituminous
Take 1kg of Coal and Explosive
Which produces more energy?
Coal produces more energy!
Approximately 6.5 x more
Coal 20 to 30MJ/kg
vs.
Anfex 3.8MJ/kg
So why don’t we use coal as an explosive?
Time
Coal burns slowly!
Coal needs additional elements- Explosives has its own oxygen
Air (Oxygen)
Combustion products from coal
Some 6.25kg of these elements required per 1kg of coal for combustion to occur
Carbon
CO2
Hydrogen
H2O
Sulphur
SO2
Oxygen
Nitrogen
NOx
Ash
An explosive produces:
A rapid reaction
Shock wave
Expansion of gases
Shock wave and rapid expansion of gases
4 x 100 kg SAN mortar
Traditional Energy conversion
www.photron.com
Fragmentation energy -> Shock
www.photron.com
Heave -> Gas
www.photron.com
Density of rock mass
High density rocks do not deform easily and require high explosive energy to fragment
But – hard rock is easy to blast
Low density rocks deform easily and require distributed low explosive energy to fragment
But – soft rock is difficult to blast
How’s this delivered?- Emulsion (Shock)
How’s this delivered?- Anfex® (Heave)
2250225022502250
2500250025002500
2750275027502750
3000300030003000
3250325032503250
3500350035003500
Det
onat
ion
Velo
city
Det
onat
ion
Velo
city
Det
onat
ion
Velo
city
Det
onat
ion
Velo
city
(m/s
)(m
/s)
(m/s
)(m
/s)
0000 2222 4444 6666 8888
% Moisture% Moisture% Moisture% Moisture
No water resistanceRapid drop off in performance
Breaking effect: How is the energy delivered?
Required:
Fragmentation, movement
Unwanted:
Damage, vibration, flyrock, fumes, sensitivity.
What form of energy is required at mine?Useful energies = fragmentation, heave
Reduce wasted energy, fuel, wear & tear
load, haul, crush, mill
Want as little as possible
Fragmentation optimisation- Powder factor
Derive drilling patterns?
Drill & Blast cost
30
19
115
REE PF K A = X 6
10.8-
50
Kuz - Ram fragmentation
Fragmentation – Cost control- Energy
Compare energy cost?
Bang per buck
30
19
115
REE PF K A = X 6
10.8-
50
Kuz - Ram fragmentation
Do our customers understand our product catalogue in terms of energy?
S
S100 Eco
75
S120 Eco
75
S130 Eco
100
S135 Eco
100
Effect of different strength ratings- Ideal detonation
For the SAME emulsion chemical formulation ...
CAUTION: Different companies have different measures
Criterion 20MPa 20MPa 100MPa Heat of
Reaction
ANFO
Density
0.8 0.82 0.8 0.8
REE 99 98 112 82
How are we supposed to compareBang per buck?
Another way to look at energy is:- Non Ideal Detonation
How well is the product mixed?
Incomplete Reaction
Dependent on Confinement
Ideal assumes no rock movement
Curved Shock Front
Dependent on Diameter
How does this affect the detonation?
Detonation becomes less ideal in smaller diameters
Detonation pressure is reduced
Velocity of detonation decreases
HSBM – The Blast Modelling Tool
Rock movement vs. timing (muckpile heave)
Mixing for grade control
Blast Modelling Outputs – Getting it right
Mineral re
covery
% Retained
New design methodology- Fragmentation for Mineral recovery?
Fragment Size
Fines OversizeMid Range0
Haulage
% Retained
New design methodology- Or fragmentation for Load & Haul?
Fragment Size
Fines OversizeMid Range0
Energy of AEL Bulk Explosives – 100MPa
Pump < 165 mm Augur > 165 mm
Emulsion +AN prill AN Prill + Fuel Oil + Emulsion
Overburden (Hard - Soft Rock)Quarrying (Hard Rock)
Low VODHigh VOD
Explosives selection to meet rock structure and strength properties
Fractures
Strength
High VODHigh density-S235
Quarry Academy
Explosives Selection is meeting the rock structure and strength properties
Fractures
Strength
Explosives selection to meet rock structure and strength properties
Fractures
Strength
Quarry Academy
Medium VODHigh density- S100
Low VODLow density-S257
Explosives Selection to meet rock structure and strength properties
Fractures
Strength
Explosives Selection to meet throw and fragmentation requirements
Fragmentation requirement
Throw requirement
Low VODMed-High density
Explosives Selection to meet blast design in cast blasting
Fragmentation requirement
Throw requirement
Fragmentation requirement
Throw requirement
Low VODLow density
Explosives Selection to meet removal of cap
Fragmentation requirement
Throw requirement
Achieving the best blast performance,
necessitates the replacement of guess by
understanding, brute force by finesse and
laxity by care and precision
- T.N Hagan, 1997 ISEE
Confidence, Courage and CareBlast Performance
Dimensioning explosives energy in the blast30th October 2014
Questions?
