EXPLOSIVES Types and Properties
WHAT IS AN EXPLOSIVES? 0 Chemical compounds or mixtures that are
initiated by HEAT, S H O C K or a
combination of both. 0Decomposes
or explodes very r apidly
and Violently 0Produces
a rapid release of HEAT and large quantities of High Pressure Gas
Detonation Process Primary Reaction Zone
Path of Detonation Expanding Gases
Detonation Process
CLASSIFICATION OF EXPLOSIVES
HIGH EXPLOSIVE (Detonation)
Low Explosives (Deflagration) Black Powder Gun Powder
Initiation/Primary SECONDARY Lead Azide TNT Mercury Fulminate ANFO Emulsions
TYPES OF EXPLOSIVES
Explosives IDEAL (Molecular) TNT PETN NG Lead Azide “$ EXPENSIVE $”
$
NON-IDEAL (Composite) ANFO Emulsions Heavy ANFO
“$ COST EFFECTIVE $”
Comparative Build Up
Definitions That Apply To Explosive Manufacturing 0PRECURSORS - Non-explosive raw materials
used in the preparation of a BLASTING AGENT (Ammonium Nitrate, Fuel Oil, Emulsion Matrix} 0BLASTING AGENTS - Term used to describe
Non-Ideal Explosive mixtures 1. Prepared from Precursors 2. Not Cap sensitive 3. Manufactured on Site
Blasting Agent Precursors Ammonium Nitrate (AN) • Principle component (oxidiser ) • Properties: Low Moisture, Free Flowing, Oil Absorbency, Low Density, Good Friability, N o n-C a k I n g
• Cycles above and below 35 - 37o C • Decompose around 250o C release O2 • Can detonate under extreme conditions
Blasting Agent Precursors Fuel Oil (FO) • Fuel component (Distillate) • Flashpoint greater than 61o C • Fuels such as petrol or kerosene must never be used (flashpoints below 61oC) making them too volatile
Blasting Agent Precursors Emulsion (Matrix) • Viscous liquid mixture of oxidiser/water solution suspended in fuel • Stabilised with emulsifiers • Dangerous Good until density is reduced by adding sufficient ANFO or by Gas or solid sensitisation
Physical Properties of Explosives
Density • How close or small the particles are the higher the density and greater the weight • Measured as grams per cubic centimetre (g/cc) • Weight compared to water (1.00g/cc) float or sink
• Higher density explosives is normally suited to HARD massive rock and low density explosives more suitable to SOFT jointed rock • Determines the weight of explosive per blasthole
Critical Density “Critical Density is when the product is so dense that there is not sufficient gas voids for the creation of hot spots to allow detonation”
• Explosives density and sensitivity are related • Deadpressing occurs when gas voids are destroyed (by abuse, shock waves) reducing sensitivity
SENSITIVITY Explosives require the creation of hot spots to maintain the reaction
Types of Test Gap sensitivity Drop Test Minimum Primer
SENSITIVITY Touch Heat No2 Detonator No6 Detonator No8 Detonator Booster
LEAD AZIDE
NG
DYNAMITE
CAP SENSITIVE EMULSION
BULK EMULSION
BLASTHOLE LOADING DENSITIES BLASTHOLE DIAMETER
BLASTHOLE DIAMETER
(mm) 89 102 108 114 121 127 130 152 159 165 187 203 210 229 251 267 270 279 286 311 349 381 432
(inches) 3½ 4 4¼ 4½ 4¾ 5 5 1/8 6 6¼ 6½ 7 3/8 8 8¼ 9 9 7/8 10 ½ 10 5/8 11 11 ¼ 12 ¼ 13 ¾ 15 17
EXPLOSIVE 0.8 4.99 6.55 7.35 8.19 9.22 10.16 10.65 14.55 15.93 17.15 22.03 25.96 27.78 33.03 39.69 44.91 45.92 49.03 51.53 60.93 76.73 91.44 117 56
0.85 5.30 6.96 7.81 8.70 9.80 10.80 11.31 15.46 16.92 18.22 23.40 27.58 29.52 35.10 42.17 47.71 48.79 52.10 54.75 64.73 81.52 97.16 124 91
0.9 5.61 7.37 8.27 9.21 10.38 11.43 11.98 16.37 17.92 19.29 24.78 29.20 31.25 37.16 44.65 50.52 51.66 55.16 57.97 68.54 86.32 102.87 132 25
WEIGHT
1 6.24 8.19 9.18 10.23 11.53 12.70 13.31 18.19 19.91 21.44 27.53 32.45 34.72 41.29 49.61 56.13 57.40 61.29 64.41 76.16 95.91 114.30 146 95
1.1 6.86 9.01 10.1011.26 12.68 13.97 14.64 20.01 21.90 23.58 30.29 35.69 38.20 45.42 54.57 61.75 63.14 67.42 70.85 83.77 105.50 125.73 161 64
PER
METRE 1.15 7.17 9.42 10.56 11.77 13.26 14.61 15.30 20.92 22.89 24.65 31.66 37.32 39.93 47.49 57.05 64.55 66.01 70.49 74.07 87.58 110.29 131.45 168 99
1.2 7.48 9.83 11.02 12.28 13.83 15.24 15.97 21.83 23.89 25.72 33.04 38.94 41.67 49.55 59.53 67.36 68.88 73.55 77.29 91.39 115.09 137.16 176 34
1.25 7.80 10.24 11.48 12.79 14.41 15.88 16.63 22.74 24.88 26.80 34.42 40.56 43.41 51.62 62.01 70.17 71.75 76.62 80.51 95.20 119.88 142.88 183 69
1.3 8.11 10.65 11.94 13.30 14.99 16.51 17.30 23.65 25.88 27.87 35.80 42.18 45.14 53.68 64.49 72.97 74.62 79.68 83.73 99.01 124.6 148.5 191 0
WATER RESISTANCE “Explosives penetrated by water have their efficiency impaired” Water resistance depends on:
• Explosives ability to withstand water • Packaging of product • Type of water – Static (low pressure) – Dynamic (high pressure)
Critical Diameter “Critical diameter is the minimum diameter that a detonation will occur or continue” Caused/Determined By loss of energy from the edge effects of the detonation process
• Ideal Explosives small critical diameter • Non-ideal Explosives much larger
Critical Diameter
Chemical Stability “An explosives ability to remain chemically unchanged under specified storage conditions (shelf life)” Ideal Explosives
Excellent (molecular bonding)
Non-Ideal Explosives
Less stable (Bonding reliant on chemical additive)
Factors Affecting Chemical Stability • Temperature extremes • Poor quality raw material • Contamination
• Poor storage facilities • Combination of the above may accelerate deterioration
Fume Characteristics “Gases resulting from detonation”
Principal Gases Non-Toxic
Toxic
Carbon Dioxide
Carbon Monoxide
Nitrogen
Nitrogen Oxides
Water (steam)
Causes Water Penetration
Lack of Confinement
Poor Mixing
Not Oxygen Balanced
Velocity of Detonation “ The The speed at which a detonation occurs ”
Factors that influence VoD • Product type
Particle size (molecular, liquid, solid)
• Explosive Diameter
Slows closer to critical diameter
• Degree of confinement
Varies in the blasthole and patterns
• Degree of Priming
Steady state VoD or overdrive is achieved faster with with high energy primers
• Temperature
Higher product temperature the faster the reaction
Due to the above variables VoD is not always a good indicator as to product performance
Detonation Pressure “The application of detonation pressure to the blasthole wall as the reaction zone travels along the charge column that is responsible for the primary shock wave”
Blasthole Pressure “Pressure applied by the expanding gases to the walls of the blasthole and jointing”
Explosive Energy/Strength “Field performance has shown that fragmentation and rock displacement are not exclusively reflected in the numerical values of explosives energy/strength” RWS Relative to ANFO
10kg ANFO
RBS
Emulsion
Not all ingredients of emulsions contribute to reaction
(100%)
10Lt ANFO
Emulsion
Higher densities of emulsions put more product into the volume area
Detonating Cords 0Contains a Core of PETN 0 Sizes Vary but generally 3.6g,
5g or10g per metre 0VoD 6400 m/s 0Initiated by: No 8 caps
Detonating Cord (10g should not be initiated with cords less than 5g) 0Purpose:
Used as surface and down-hole initiating lines
Emulsion
artridges 0Contains SENSITISED emulsion
in wrapped cartridges 0 Sizes Vary from 25mm to
80mm diameters 0VoD dependant on product
type and diameter 0Initiated by: No 8 caps
Detonating Cord (10g) 0 Density 1.6 g/cc g/cc 0 Purpose:
Used for wet and small hole diameter blasting, On occasions may be used as a booster or primer
Bulk Emulsion Blends 0 Emulsion and ANFO blends are water resistance
gassed bulk emulsions designed to be pumped from a bulk delivery truck through a delivery hose to the bottom of the blasthole 0 Minimum Hole diameter depends on the product
and blend (75 - 98mm) 0 VoD dependant on product type, density, blend,
diameter, confinement, primer type… 0 Initiated by:Boosters 0 Density can be 1.00 g/cc to 1.25 g/cc 0 Purpose:
An effective Blasting Agent for wet holes that allows complete coupling in the blasthole, blasthole, allows for variable density across the shot and added ANFO can modify explosive performance if required
Emulsions Essentially a liquid oxidiser phase Suspended in a Continuous fuel phase with an emulsifier added to the fuel phase to prevent separation.
Oxidiser Phase Suspended Fuel Phase Continuous (surrounds the oxidiser)
Heavy ANFO 0 ANFO mixed with emulsion matrix in blends
where the majority of the mixture is ANFO. Heavy ANFO are ANFO based explosives with higher detonation properties and better water resistance, they are augred from a bulk delivery truck from the top of the blasthole 0 Minimum Hole diameter depends on the
product and blend (89mm - 127mm) 0 VoD dependant on product type, density,
blend, diameter, confinement, primer type… 0 Initiated by:Boosters 0 Density can be 0.85 g/cc to 1.30 g/cc 0 Purpose:
Emulsion provides a water resistant coating to the ANFO, this increases the bulk density, hence higher energy
