Blasting Competency Program B1. Introduction to Explosives
May 2010
Introduction to Explosives
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1
What is an explosive?
Take 1 kg of Coal and Explosive Which produces more energy?
Coal produces more energy!
Approximately 6.5 x more (Coal 20 to 30 MJ/kg vs. Anfex 3.8 MJ/kg)
2
So why don’t we use coal as an explosive?
Time Coal burns slowly!
An explosive requires:
A rapid reaction, A shock wave and Expansion of gases
3
Coal needs additional elements
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Safety with explosives
Explosives
DO NOT require presence of air (Oxygen) to function
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Definition of an explosive…
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Definition of an explosive
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Evolution of explosives…
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Evolution of explosives…
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Development of modern explosives
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The explosive reaction
Provides Oxygen e.g. Ammonium Nitrate Solution
To react with the oxygen e.g. Fuel Oil and/or Aluminum, Carbohydrates
Provides the “Hot Spot” to drive reaction, more surface area e.g. Chemical gassing: Sodium Nitrite Mechanical: Micro balloons
e.g. Detonator, Booster, cartridge etc.
Do we need a sensitiser for Anfo? No, creation of more surface area by the size/breakdown of prills
7
Definition - Combustion ) 2
Definition - Detonation )
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Definition - Deflagration )
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Low and High explosives
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Detonator sensitive explosive
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A Typical detonator contains more than double this amount of PETN
Properties of explosives
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Properties of explosives
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Handling characteristics
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Water resistance
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Effect of water at toe of blasthole
Influence of moisture content (ANFO 94% AN 6%FO)
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What is Density?
Density
Mass Volume Blasthole
Thus more mass of explosives for same volume of blasthole
Rock
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Why is density critical to explosive performance?
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Sensitivity
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Detonator sensitive
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Primer sensitive
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What’s happening here?
Initiating system
Stemming
Booster
Explosive
Booster Proposed Floor Rock (Weight)
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Velocity of detonation
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Critical diameter
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Effective energy of explosives
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Detonation
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Ideal detonation
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Non Ideal detonation
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Relative Effective Energy Relative Weight Strength (RWS)
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ANFO – 0.8 g/cc (94.3% AN 5.7% FO), 2.9 MJ/kg
Relative Bulk Strength
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3 3 #4 3 5
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Energy of AEL Bulk Explosives
200
% Emulsion Density g/cc*100 RBS
180 160 140 120 100 80 60 40 20 0
Augur
Pump AN + PPAN
AN + ANFO
Post detonation fumes
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Oxygen balance
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Desensitisation of explosives
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Detonator cord
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Explosive
Booster Proposed Floor
Channel Effect
Downlines
Rock (Weight)
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Storage life
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Temperature effects
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Ammonium Nitrate
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AN Properties
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Temperature Cycling • • •
Becomes a problem if the temperature moves above and then below 32°C repeatedly Prills will fracture and cake Storage needs to be cool and dry
23
Bulk Explosives
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1944, Discovery of ANFO
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Mixing ANFO
ANFO Properties
• • • • • • •
AEL Trade name, ANFEX Fuel Oil content Density – 0.76 to 0.78 Water Resistance – a limitation Charge Diameter Particle size – affects sensitivity Sensitivity
Sensitivity/Energy
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Bulk Emulsion…
Bulk Emulsion…
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Blasting Agent - “Non detonability test”
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Bulk Heavy ANFO
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Synergy S1000 Heavy ANFO Range
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Bulk vs. ANFO
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Packaged Explosives
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Emulsion
• Is an intimate mixture of two immiscible liquids, with one liquid phase dispersed uniformly throughout the second phase. The oil of fuel phase surrounds and coats all the oxidiser droplets. •
Watergel
• Typically a thickened aqueous (water) solution of oxidiser and/or fuel salts in which is dispersed additional solid oxidisers and/or fuels as well as sensitisers
Emulsion based
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Emulsion based
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Watergel Explosives
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Optimisation Criteria (NOT Unit Cost!)
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Caterpillar Study…
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Acknowledgement: David Carletti, Caterpillar Australia
31
Caterpillar Study
Cost/tonne
“Ideal”
Fine
Coarse
Acknowledgement: David Carletti, Caterpillar Australia
Mass of explosives in Blasthole (kg)
# %
"
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L 17. / L C. 1/
D
Stemming
Explosive
= 10.5 x 7.15 = 75.1 kg
Total Charge Length
• Total Charge (kg) = Total Charge Length x Mc
Proposed Floor
32
Mass of explosives in Blasthole (kg)
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L M. C L 7. H
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L >J L M. CJ 7. HL 17. /
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Proposed Floor
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Sub-drill - U
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Total Charge Length
L HM
Charge Length - L
Explosive
+
Stemming
Mass of explosives – Mc (kg/m)
Hole diameter Inches (mm)
0.65
0.70
0.75
0.80
0.85
0.90
3 1 3 /2 4 1 4 /4
76 89 102 108
2.95 4.04 5.31 5.95
3.18 4.35 5.72 6.41
3.40 4.67 6.13 6.87
3.63 4.98 6.54 7.33
3.86 5.29 6.95 7.79
4.08 5.60 7.35 8.24
4 1/2
114
6.63
7.14
7.66
8.17
8.68
4 /8 5 1 5 /8
7
124 127 130
7.85 8.23 8.63
8.45 8.87 9.29
9.06 9.50 9.95
9.66 10.13 10.62
10.26 10.77 11.28
5 /4
1
133
9.03
9.73
10.42
11.11
11.81
5 1/2
140
10.01
10.78
11.55
12.32
13.08
5
5 /8
143
10.44
11.24
12.05
12.85
5 7/8 6 6 1/4
149 152 159
11.33 11.79 12.91
12.21 12.70 13.90
13.08 13.61 14.89
13.95 14.52 15.88
6 3/4
171
14.93
16.08
17.22
7 /8
3
187
17.85
19.23
20.60
7 5/8
194
19.21
20.69
22.17
7 /8
7
200
20.42
21.99
8 /2 9 7 9 /8 10 5 10 /8
1
216 229 251 254 270
23.82 26.77 32.16 32.94 37.22
11 1/4
279 311 349 381 406 445
3
12 /4 13 15 16 1/2 17
Density of Explosives (g/cc) 0.95 1.00 1.05 1.10
1.15
1.20
1.25
1.30
1.35
1.40
4.31 5.91 7.76 8.70
4.54 6.22 8.17 9.16
4.76 6.53 8.58 9.62
4.99 6.84 8.99 10.08
5.22 7.15 7.15 9.40 10.54
5.44 7.47 9.81 10.99
5.67 7.78 10.21 11.45
5.90 8.09 10.62 11.91
6.12 8.40 11.03 12.37
6.35 8.71 11.44 12.83
9.19
9.70
10.21
10.72
11.23
11.74
12.25
12.76
13.27
13.78
14.29
10.87 11.40 11.95
11.47 12.03 12.61
12.08 12.67 13.27
12.68 13.30 13.94
13.28 13.93 14.60
13.89 14.57 15.26
14.49 15.20 15.93
15.10 15.83 16.59
15.70 16.47 17.26
16.30 17.10 17.92
16.91 17.73 18.58
12.50
13.20
13.89
14.59
15.28
15.98
16.67
17.37
18.06
18.76
19.45
13.85
14.62
15.39
16.16
16.93
17.70
18.47
19.24
20.01
20.78
21.55
13.65
14.45
15.26
16.06
16.86
17.67
18.47
19.27
20.08
20.88
21.68
22.48
14.82 15.42 16.88
15.69 16.33 17.87
16.56 17.24 18.86
17.44 18.15 19.86
18.31 19.05 20.85
19.18 19.96 21.84
20.05 20.87 22.83
20.92 21.78 23.83
21.80 22.68 24.82
22.67 23.59 25.81
23.54 24.50 26.81
24.41 25.40 27.80
18.37
19.52
20.67
21.82
22.97
24.11
25.26
26.41
27.56
28.71
29.86
31.00
32.15
21.97
23.34
24.72
26.09
27.46
28.84
30.21
31.58
32.96
34.33
35.70
37.08
38.45
23.65
25.13
26.60
28.08
29.56
31.04
32.52
33.99
35.47
36.95
38.43
39.90
41.38
23.56
25.13
26.70
28.27
29.85
31.42
32.99
34.56
36.13
37.70
39.27
40.84
42.41
43.98
25.65 28.83 34.64 35.47 40.08
27.48 30.89 37.11 38.00 42.94
29.31 32.95 39.58 40.54 45.80
31.15 35.01 42.06 43.07 48.67
32.98 37.07 44.53 45.60 51.53
34.81 39.13 47.01 48.14 54.39
36.64 41.19 49.48 50.67 57.26
38.48 43.25 51.95 53.20 60.12
40.31 45.31 54.43 55.74 62.98
42.14 47.37 56.90 58.27 65.84
43.97 49.42 59.38 60.80 68.71
45.80 51.48 61.85 63.34 71.57
47.64 53.54 64.33 65.87 74.43
49.47 55.60 66.80 68.41 77.29
51.30 57.66 69.27 70.94 80.16
39.74
42.80
45.85
48.91
51.97
55.02
58.08
61.14
64.19
67.25
70.31
73.36
76.42
79.48
82.53
85.59
49.38 62.18 74.11 84.15 101.09
53.18 66.96 79.81 90.62 108.87
56.97 71.75 85.51 97.10 116.65
60.77 76.53 91.21 103.57 124.42
64.57 81.31 96.91 110.04 132.20
68.37 86.10 102.61 116.52 139.98
72.17 90.88 108.31 122.99 147.75
75.96 95.66 114.01 129.46 155.53
79.76 100.45 119.71 135.93 163.30
83.56 105.23 125.41 142.41 171.08
87.36 110.01 131.11 148.88 178.86
91.16 114.79 136.81 155.35 186.63
94.96 119.58 142.51 161.83 194.41
98.75 124.36 148.21 168.30 202.19
102.55 129.14 153.91 174.77 209.96
106.35 133.93 159.61 181.25 217.74
33
Mass of explosives – Mc (kg/m)
MC =
× D2 kg/m 1273
1.15 × 89 2 MC = kg/m 1273
= 7.15 kg/m
Mass of explosives in Blasthole (kg)
# %
#
"
"
>
L 17. / L C. 1/
Stemming
D
% Total Charge Length
Explosive
& ( L# " > L 17. / C. 1/ L C/. 1
Proposed Floor
34
On Bench control - Total mass of explosives?...
Not to scale
Total mass of explosives?
)
)
L 20
%
L 75.1 kg
#
L 75.1 x 20 = 1502 kg
35
Stock of initiating systems and boosters on bench?...
Not to scale
Stock of initiating systems and boosters on bench? ) ) ) )
) 2 .. 98 ) 2
L 20 L 20 L 19 L 1
Not to be brought on to the bench!
IED – Instantaneous Electric Detonator
36
Powder factor
20 m
30 m
10 m Not to scale
Powder Factor - Volume =
) )
& %
L
A(
3
9
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2 ( L 17 A7 *7 L -777 A
%
L 1/7* 2
L
% =
L 1/7*D -777L 7. */
) ) D
A
37
Powder Factor - Mass %
) ) L9 ' L *. K L 1KK77
%
& ( = -777
L 1/7* 2
L
% %
) )
L 1/7*D 1KK77L 7. 17
#
D
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38
