Explosives and Initiating Device.pdf

MODULE-2
EXPLOSIVES AND INITIATING SYSTEMS
MANAS KUMAR MALLICK
ASSISTANT PROFESSOR
DEPARTMENT OF MINING ENGINEERING
BIT SINDRI, DHANBAD

What is Explosives?
Explosive is a solid or liquid substance or a mixture of substances which
on application of a suitable stimulus is converted in a very short time
interval into other more stable substances, largely or entirely gaseous,
with the development of heat and high pressure.
OR
Commercial explosives are those that are a mixture of compounds, some
combustible and some oxidizing which, when properly initiated, have an
almost instantaneous exothermic reaction that generates a series of high
temperature gaseous products that are chemically more stable and take
up a larger volume.
OR
An explosive is a substance which, when properly initiated, is very rapidly
converted to gases at high temperature and pressure. This process is
called detonation.

Characteristics of Explosives
 It is a chemical compound or mixture ignited by heat,
shock, impact, friction, or a combination of these
conditions.
 Upon ignition, it decomposes rapidly in a detonation
 There is a rapid release of heat and large quantities of
high-pressure gases that expand rapidly with sufficient
force to overcome confining forces.
 The energy released by the detonation of explosives
produces four basic effects; (a) rock fragmentation; (b)
rock displacement; (c) ground vibration; and (d) air
blast

Properties of Explosives
1) Effective Energy/ Strength:
 Effective energy is defined as the total energy released by
the explosive gases as they expand and do useful work from
the initial detonation.
 Relative weight strength(RWS) is defined as the effective
energy of an explosive compared to the effective energy of
an equal weight of standard ANFO (i.e. 94% AN, 6% FO,
density = 0.8 g/cm3). RWS is expressed as a percentage, with
that of ANFO being 100%.
 Shock and heave energy- Energy is delivered by an explosive
in two main forms, shock energy and heave energy. The
gases continue to expand, forcing their way into fractures
created by the shock wave, and displace the fractured rock
outwards. This latter effect of the expanding gases is termed
heave.

Continued
• Relative Weight Strength (RWS) : This is the
ratio of energies of a unit weight of explosive
compared to an equal weight of ANFO.
• Relative Bulk Strength (RBS) : This is the ratio
of the energies available in a given volume of
explosive compared to an equal volume of
ANFO.
RWS (Explosive) = [AWS (Explosive)/ AWS (ANFO)] * 100
RBS (Explosive) = [ABS (Explosive)/ ABS (ANFO)] * 100

Numericals
(Q-1) The weight strength of ANFO of specific
gravity 0.8 is 912 kcal/kg. The weight strength
of an emulsion explosive of specific gravity 1.2
is 850 kcal/kg. Calculate the Bulk strength of
the emulsion explosive relative to ANFO in
percentage.

2) Density:
The density of an explosive may be expressed in terms of
specific gravity. Specific gravity is the ratio of the density of
the explosive to the density of water under standard
conditions. Density is an important consideration when
choosing an explosive. For difficult blasting conditions or
where fine fragmentation is required, a dense explosive is
usually necessary. In easily fragmented rock or where fine
fragmentation is not needed, a low-density explosive will
often suffice. Low-density explosives are particularly useful in
the production of riprap or other coarse products . The
density of an explosive determines the charge weight per
meter of hole

3) Water Resistance:
An explosive's water resistance is a measure of its ability to
with stand exposure to water without deteriorating or losing
sensitivity. Sensitivity is the ease with which an explosive
detonates. Blasting often takes place in wet conditions, even
underwater for special tasks. In these cases, the water
resistance of an explosive is a very important consideration.
4) Velocity of Detonation
The velocity of detonation (VOD) is the rate at which the
detonation wave travels along an explosive column. The
greater the VOD the greater the power or ‘shattering’ effect
of an explosive.

5)Detonation Pressure
Detonation pressure is the pressure in the reaction zone as an
explosive detonates. It is a significant indicator of the ability of
an explosive to produce good fragmentation. A high
detonation pressure is one of the desirable characteristics in a
primer.
5) Sensitivity
Sensitivity is a measure of the ease with which an explosive
can be detonated by heat, friction or shock and of its ability to
propagate that detonation. Modern commercial explosives
can be grouped into two main categories according to their
sensitivity, detonator sensitive explosives and blasting agents.

6) Fume Characteristics
The gases produced by the detonation of an explosive consist
mostly of non-toxic carbon dioxide, nitrogen and steam. Small
amounts of toxic gases are also produced, the main ones
being carbon monoxide and oxides of nitrogen.
7) Storage Properties
Explosives deteriorate and shelf life is particularly affected by
both climate and magazine conditions. The maintenance of
explosives magazines is also subject to Statutory Regulations.

Classification of Explosives
• There are many ways to classify explosives.
• One is to think of mixtures as part fuel or sensitizer and part
oxidizer (or something that provides oxygen to the fuel).
Examples of fuels and sensitizers, as well as oxygen source.
Fuel oil (FO), Carbon Aluminum
Trinitrotoluene (TNT), Cyclonite (RDX),
Smokeless powder, Micro-balloons
and PETN
Ammonium nitrate (AN)
Calcium nitrate
Sodium nitrate

Low Explosive, High Explosive and Basting Agent
• Low explosive (LE) = An explosive
material that can be caused to
deflagrate (burn) when unconfined.
• High explosive (HE) = An explosive
material that can be caused to
detonate with a No. 8 blasting cap
when unconfined.
• Blasting agent (BA) = A mixture
consisting of a fuel and oxidizer,
intended for blasting but otherwise
not an explosive (cannot be
detonated with a No. 8 blasting cap).

Cap sensitive and Non cap sensitive
• High Explosives, that can be detonated directly with
a No. 8 cap are called cap-sensitive
• Blasting Agents, that cannot be detonated directly
with a No. 8 cap are called cap-insensitive or non-
cap-sensitive
• A number 8 test blasting cap is one containing 2
grams of a mixture of 80 % mercury fulminate and 20
% potassium chlorate, or a blasting cap of equivalent
strength.

Low Explosives
• It burns and develop much low pressure.
• The example of low explosive is Gun powder/ black
powder
• It is a mechanical mixture of Potassium Nitrate (72-
75%), Charcoal (15-16%) and Sulphur (10-12%)
• Ignition speed is 450 m/sec .
• Poor fragmentation with heaving effect.
• Used in manufacture of safety fuse; extraction of
ornamental blocks; breakage of elasto-plastic
materials.

High Explosives
• Characterized by very high rate of reaction and high
detonation pressure.
1. Nitroglycerin (1845)
2. Dynamite (1860)
3. Dynamite perfected and Non-NG, High AN, Cap Sensitive
(1930 – 50)
4. ANFO (1947)
5. LOX (1930, in India)
6. Slurry (1960-62)
7. Cap-sensitive Slurry (1970)
8. Emulsion (1978)
9. Bulk Explosives (1980 -90)

NG based Explosives
• Compositions: NG: 5%-90%; NC: Gelling/thickening agent &
sensitizers; Oxidizer-AN & SN; Fuel ingredients- Starches,
wood flours, sulphur; NaCl-in permissible limit.
• Sensitive to shock, friction & heat
• High VOD of 7800 m/sec ; temp@detn.- 3150 deg. C
• Chemical reaction:
• Density of explosive is varies from 0.8-1.45,
• Relative Bulk Strength: 73-79%, Temperature-17 degree

NG based Explosives
Advantages:
• High strengths
• High densities
• High detonation velocity
• Greater water resistance
and chemical stability
Disadvantages:
• Risk of accidents
• Sensitive to friction and
heat
• Handling problems
• High manufacturing
cost

Ammonium Nitrate Fuel Oil (ANFO)
• Composition of ANFO: 94 % AN + 6 % FO (Oxygen Balanced)
• Fuel Oil : Diesel Oil No.2 ( for 50 kg of AN-3.7 liters)
• It is a cheap, low-density, Non-cap sensitive explosive, requiring primer
charge of high explosives for detonation.
• Sensitivity and Performance of AN, depends on ‘quality’ of the Prill
supplied
• Sensitivity or Energy is increased by adding Fuel grade Aluminium powder
• 5 % aluminium powder increases 13 % strength when mixed with ANFO
• 15 % aluminium powder increases 35 % strength when mixed with ANFO
• Chemical Reaction:
• Specific gravity: 0.8-0.9
• Relative Bulk Strength: 51-55%
• Velocity of Detonation (VOD): 3500 m/sec
• Detonation Pressure: 20 – 25 kbar

• Weight Strength : 75 – 80 %
• Dry season : 7 litre of diesel, Wet season : 9 litre of diesel
• Diesel oil > 8 %, the sensitivity of ANFO get reduced
• Small quantity of OCG is used as booster for detonating ANFO
• It causes irritation in skin.
• Dry BA’s comprise blasting-grade prilled AN (as the oxidizer), of
grain sizes between 1 to 2 millimeters in diameter and porosity
between 8 to 12 percent, onto which is absorbed diesel oil (FO, as
a fuel).
• Ammonium Nitrate + Fuel Oil = ANFO
• Today, ANFO is the most widely used explosive in the blasting
industry, because it is relatively inexpensive and safe to handle.

Dry Blasting Agent (ANFO)
• Explosive-grade prills are made in a prill
tower in which a hot, supersaturate AN
liquid (4-percent water)along with other
additives to achieve porosity is dropped
from spray nozzles at a height of 100 to 200
feet against an updraft of warm air.
• Droplets of the AN solution crystallize as
they fall; the longer the droplets are
suspended, the larger the prill diameters.
• The crystallized AN particles are then
completely dried and coated with
surfactants and clay to minimize porosity
and protect the surface from absorbing
water in preparation for fuel absorption.

Advantages:
 Superior in cost
effectiveness
 Safe to handle
 Best suitable for dry holes
 Explosive is prepared only
at the site
 No storage in magazine
required
Disadvantages:
 Desensitized in water
 Inefficient in small diameter
holes
 Unsuccessful blasting in hard
rocks
 Lower sensitivity
 Not suitable for sleeping
holes & hot holes

Numericals
1. The oxygen balanced equation for explosive
ANFO is given below:
• For 100 litre of fuel oil having density 850
kg/m3, find out the quantity of ammonium
nitrate to be mixed in kg.

Liquid Oxygen Explosives (LOX)
• It is made by soaking cartridge of activated
charcoal-27%, (combustible ingredient) in
liquid oxygen (73%).
• High detonation pressure (14*10000 atmos.)
• Large volume of gas is released at high
temperature
• VOD: 3000 - 3200 m/s

Liquid Oxygen Explosives (LOX)
Advantages:
• Suitable for dense and
medium rocks
• No emission of noxious
gases
• It causes less vibrations
than conventional
explosive
• Misfires can be handled
safely after lapse of
certain duration
Disadvantages:
• Cost is high
• Quicker evaporation ( life
is shorter)
• Unsafe

Slurry Explosives
• Addition of colloid such as ‘Guargum’ in ANFO, which
builds up ‘Viscosity’, followed by Crosslinking agent
which forms a gelled mixture.
• Compositions: Oxidizer: AN, SN, CN; Explosive Fuel
Sensitizer: TNT, PETN, Al Powder, Non explosive Fuel
Sensitizers: Sugar, Urea, Paraffin, Glycol, Wood pulp
Gelling agent: Guar gum or Starch, Cross linking
agent:Potassium or Sod. Di-Chromates or Borax oxides,
• Plant mixed slurry or Site mixed slurry
• Detonation velocity: 3000-4500 m/sec
• Density:1.05-1.6
• Relative Bulk Strength: 53-65%
• Detonation Pressure: 50- 100 kbar

Slurry Explosives
• Slurry explosives are used in large OCP as bulk
form and in underground as cartridge form.
• To make it fit for underground, mixture of
ammonium chloride and sodium nitrate are
directly added. A sheath of sodium bi-
carbonate is used.
• For better performance diameter of blast hole
shall be at least 62 mm or more.

Slurry Explosive
• A water-gel or slurry explosive is a
gelatinous aqueous solution that
consists of an oxidizer, such as AN,
and a fuel.
• Typically, the fuel will contain
additional dispersed solid oxidizers,
fuels, and sensitizers such as
aluminum or other explosives.
• Wet-BA fuel may also contain
micro-balloons (hollow bubbles of
glass).
• The difference between a slurry
and water gel is that water gel is
made water-resistant by the
addition of a cross-linking or
chemical-bonding agent; a slurry,
on the other hand, is water-
resistant (formulated to be miscible
in water) by nature.

Slurry Explosives
Advantages:
• Water resistant
• Effective utilization of
explosives
• Not subjected to
friction or impact
• It produces low non-
toxic fumes
Disadvantages:
• Life is only 6 months
• Not suitable for high
temperature
conditions

Emulsion Explosives
• Emulsion explosives are the intimate and homogenous
mixture of two immiscible phases i.e. oxidiser (internal
phase) and fuel (external phase).
• The internal phase is composed of solution of oxidiser salts
e.g. Ammonium Nitrate etc. dispersed as microscopically
fine droplets, which are surrounded by a continuous fuel
phase.
• It is a mixture of two liquid which doesn’t dissolve in each
other but it is made to dissolve with emulsifying agent. The
mixture so formed which is called emulsion.
• Ammonium Nitrate is used as oxidiser and fuel oil is used
which is in liquid form and they are forcefully mixed by
adding emulsifying agent.
• It is used in OCP as bulk form and in underground it is used
as cartridge form.

Emulsion Explosives
• The external phase (green) – 5 to 9% Mineral oils,
Diesel fuels, Recycled oils, Vegetable oils, Aqueous salt
• The internal phase (blue) – 91 to 95% Ammonium
Nitrate, Calcium Nitrate, Sodium Nitrate, Per chlorates
• A bulking/gassing agent – for density control, is then
dispersed thorough out the basic emulsion matrix. The
gassing agent can either be ultra fine air bubbles or
artificial bubbles from glass, resin or plastic. The
bulking agents determine and control the sensitivity of
emulsion products, whether emulsion is cap sensitive
or booster sensitive

Emulsion Explosives
• Critical diameter of emulsion explosives again
depends upon droplet size and sensitizer used.
• Because of the intimate mixture between oxidizer
and fuel, emulsion explosives have higher energy
than water gel slurries or ANFO and it matches
with energy level of Nitroglycerine based
explosives.
• Since Emulsion explosives are well oxygen-
balanced, generates a minimum of noxious fumes
and far less smoke.

Emulsion Explosive
• Consists of oxidizers which is fine particle size
dissolved in water surrounded by a fuel
• Sensitizer: air/gas bubbles or artificial glass micro
balloons-hot spot; Emulsifier-waxes, gums
• VOD: 4500-5500 m/s
• Density: 1.1 to 1.35 g/cc
• High water resistant in full concentration
• Plant Mixed Emulsion (PME) or Site Mixed
Emulsion (SME)
• High Bulk strength
• Detonation Pressure: 100-120 kbar

Charging a hole with Emulsion Explosive

Emulsion Explosives
• Emulsions are “water-in-oil” mixes that
were developed in the early 1960’s to
improve the performance of water gels.
• They amount to hot solutions of oxidizer
salts (consisting of ammonium Nitrate,
calcium Nitrate or sodium Nitrate) mixed
with oil and an emulsifying agent. The oil
phase usually consists of diesel fuel
and/or mineral oil that include micro-
balloons as sensitizers.
• The oxidizer solution is broken up into
small, micron- sized droplets, which form
a discontinuous phase within the
continuous oil phase.
• The small size of the liquid-nitrated salt
particles provides a large surface areas-
to-volume ratio that amounts to more
fuel being placed in intimate contact with
the oxidizer. This, in turn, allows for a very
fast detonation rate and a powerful
explosive.

Emulsion Explosive
Advantages:
• High output of thermo-chemical energy
• Cap sensitivity in low temperatures
• Safety
• Maximum Reaction factor of 0.97
• Low cost
• Low Post-detonation fumes
• Owing to their very small particle size, emulsion
ingredients can achieve a very uniform mix.
• Emulsions are extremely water- resistant.

Emulsion Explosive
Disadvantages:
• It causes problems when loading holes with fissures
• Over time (with long shelf life), salt crystals may grow
and/or oil migrate in an emulsion, allowing the AN
liquid- phase droplets to join and create larger droplet
sizes whose bulk surface areas are smaller. Under such
a scenario, less oxidizer would be in contact with the
fuel and the sensitivity of the emulsion would
decrease.
• Emulsions are expensive.
• Sympathetic detonation

Bulk Explosives
• Explosives directly delivered into the blast hole
through mechanised and mobile delivery
system
• Supplied to large opencast mines and civil
construction projects
• Useful, annual explosive consumption- 2000 t
• Types – Bulk ANFO, Bulk Watergel, Bulk
Emulsion, HANFO

Bulk ANFO
• Prilled AN (94%) + Diesel oil (6%) Initiation by
DF or NONEL
• Suitable for medium hard rock
• Not suitable for wet holes
• Very limited shelf life
• Not suitable for variable climatic conditions
• Economically cheaper than the rest

Heavy ANFO
• Loose Emulsion matrix physically with ANFO for
creating voids to provide sensitivity
• Mixture depends on required sensitivity, energy,
water resistance and economics
• Emulsion : ANFO – 30:70
• Relative RBS and strength increases with
emulsion content but sensitivity reduces.
• It Increases the density of ANFO; hence, increase
energy in the borehole.
• It provides water resistance to ANFO

Heavy ANFO
• When waterproof heavy ANFO blend is loaded
into wet holes it should always be loaded from
the bottom up. This is achieved using a bulk truck
with a hose that can extend to the bottom of the
blast hole.
• The product is pumped through the hose. The
hose is retracted as loading proceeds, but is
always kept in the explosive. The water rises on
top of the advancing column of more dense
explosive. Mixing does not occur if the loading is
carefully performed.

Heavy ANFO
• Experiment has shown that the performance of Heavy
ANFO becomes sluggish as more emulsion is added
unless the emulsion has been sensitized by gassing or
micro balloons.
• It appears that in hard-rock performance will suffer
when there is more than 30 percent of un-sensitized
emulsion in the mix.
• In softer formations greater percentages of un-
sensitized product can usually be employed because
suitable fragmentation of the rock depends to a greater
degree on heave energy.
• The degree of non-ideal detonation introduced by the
lack of sensitization means that a greater degree of the
total energy is released as heave energy

Heavy ANFO (HANFO)
• Blends (or heavy ANFO’s) are mixtures of emulsions and
ANFO that are typically non-cap-sensitive. As a rule, the
ratio of emulsion (or other water-based explosive or
oxidizer matrix) to ANFO in such blends ranges as follows:

Heavy ANFO
Advantages:
• Higher RBS of 130 compared to ANFO(expansion
of drill pattern by 11%)
• Cost of Drilling is reduced by 15%
• Muck pile was low and well spread (suitable for
Dragline benches – Cast blasting)
• Blends increase the density of ANFO, which
increases the energy in the borehole; they also
provide water-resistance to ANFO.

Heavy ANFO
Disadvantages:
• Over time, fuels may migrate and salt crystals may
grow increasingly insensitive.
• When Heavy ANFO is augured into wet holes it spatters
on impact with the water, and prill goes into the solution.
Water is mixed into the explosive column. Bridging may
occur with portions of the explosive column separated by
a water gap. Since the gap sensitivity of these products is
not large this may lead to the failure of a portion of the
explosive column to detonate unless it happens to be
primed on both sides of the water gap.

Classifications of Blasting Agent
BA’s are either dry
(free- running;
shown to the left) or
wet (pourable;
shown to the right).
Wet BA’s are
formulated with
water to achieve a
density greater than
1.0.

Booster and Primers
• Boosters and primers are used to
initiate non- cap-sensitive blasting
agents that are not high explosive.
However, it is critical to remember
that these agents are themselves
High explosive. Booster and primer
can be initiated by No. 8 blasting
caps, as well as in detonating cord
and other initiating device.
• Cast pentolite boosters, shown in the
figure contain a mixture of
pentaerythritol tetranitrate (PETN)
and TNT. The typical formulation
contains 50-percent PETN and 50-
percent TNT, but some
manufacturers’ brands may contain
as high as 60-percent PETN.

Booster and Primers
• What is the difference between a
booster and a primer?
• A primer is a booster (cast or
packaged HE) in which a detonator
has been inserted.
• A booster, on the other hand, does
not contain a detonator; rather, as
its name suggests, it “boosts” the
explosive energy in a column.
• Boosters are generally cap- sensitive
HE’s that are initiated by adjacent
primers or detonating BA’s.
• Boosters may be used (1) in blast
holes that are wet at the bottom,
(2) when excess toe burden exists,
or (3) within a hard geological
strata.

Explosive Classification
• Under the Explosives Rules, the various explosives and
accessories are classified under the following headings
• Class-1 : Gun Powder
• Class -2: Nitrate mixture (Powerflo, Godyne, Pentadyne etc)
• Class-3: Nitro compounds, e.g. Blasting Gelatine, Special
Gelatine, OCG, Permitted explosives, Primex, Gelonite, Powerx
80, TNT, Gun cotton, PETN etc.
• Class-4: Chlorate mixtures
• Class-5: Fulminate
• Class-6: Safety fuse, Detonating fuse, Detonators, Delay
detonators
• Class-7: Fireworks
• Class-8: Liquid Oxygen Explosives

Classification of explosives on the basis of risk
• Category X : Explosives having a fire or a slight explosion risk
or both but the effect is local.
• Category Y: Explosives having a mass fire risk or a moderate
explosive risk but not the risk of mass explosion
• Category Z: Explosives having a mass explosion risk and
major missile effect.
• Category ZZ: Explosives having a mass explosion risk and
minor missile effect.
• Schedule viii of the explosive rules give the safety
distances to be observed for/from magazine, licensed of
the storage high explosives, of different capacities, of
the different categories(X, Y, Z and ZZ) of the explosives.

Classification of Explosives on the basis of Strength
• Low Explosive : Where the VOD is less than the
velocity of sound (sub sonic), Gun powder
• High Explosive: Where the VOD is more than the
velocity of sound (super sonic), Slurry, Emulsion,
Dynamites

Classification of Explosives on the basis of Sensitivity
• Cap Sensitive: The explosives which can be
detonated by a No. 8 detonator (all permitted, all
NPSD, LD boosters/primers
• Non Cap sensitive: The explosives which can not
be detonated and need a cap sensitive explosive
for detonation (ANFO, LD column charge)

Basis of permitted and non permitted
• Permitted Explosives: For use in underground
gassy coal / non coal mines or excavations
with explosive environment.
• Non-Permitted Explosives:
• Small Dia.(NPSD): For use holes of small dia.
(32 mm dia. (Pradhan), <165 mm (Langefors)
• Large Dia.(LD): For use holes of large dia.
(>100 mm (Pradhan), >165 mm (Langefors)

Explosive storage and handling
• Explosives, by their very definition, are potentially unstable
compounds. They will deteriorate if exposed to unsuitable
conditions such as heat or humidity.
• Different types of explosives have a varying shelf life,
depending on how they are stored and used.
• Every application for the grant of license in Form-22 to
possess explosives to use.
• For capacities more than 200 kg – Chief controller of
explosive (CCOE)
• For any quantity of liquid oxygen explosive and bulk
explosive- Chief controller of explosive (CCOE)
• For capacities of less than 200 kg- Controllers of explosives

Procedure to establish a Magazine
• Every application for the grant of license in
Form-22 to possess explosives for use.
• License Authority:
• For capacities of more than 200 kg – Chief
Controller of Explosives (CCOE)
• For any quantity of LOX and bulk explosives –
CCOE
• For capacities of less than 200 kg-Controller of
Explosives (COE)

Procedure to establish a Magazine
• Plans, draw to scale of the proposed premises
and of the site on which the magazine is to be
located.
• Drawing of Magazine
• Whenever the application is made for a
company, the name, address, specimen
signature of the person or persons authorized
to sign correspondence has to be mentioned.
• NOC from railway (if within 100 m)

Classification of Magazine
• Magazine can be broadly classified as:
1. Mode ‘A’ Magazine
2. Portable Magazine/ Mode ‘B’ Magazine
3. Underground Magazine
4. Reserve Stations

Mode ‘A’ Magazine
• Mode A magazine is the magazine and this is of very
large quantity of explosive can be stored in this
magazine.
• This type of magazine must be approved, must be
approved by the chief controller of explosive.
• This type of magazine should have walls if it is of
reinforced concrete, then the concrete walls should
have a thickness of 225 millimeter. If it is of brick stone,
in that case, it must be of 450 mm thick.
• It must have a concrete roof and the reinforced
concrete roof layer should have one 50 mm thick; that
means, 6-inch-thick concrete roofing is required.

• One ventilator must be provided or one or more
ventilator must be provided in to the magazine
for ventilating the air inside so that heat cannot
be accumulated, and the gases generated from
the explosive must be taken out.
• One ventilator is required in the top, and in the
side walls. If the capacity of the magazine is less
than equal to 500 kg, 2 or more for the more
than 500 kg, and this is the specification of the
ventilator.

• This is if you are having this magazine capacities
of 2 tonne. Then the internal safety distance is 31
meter for zz category of explosive; that means
the most dangerous explosive.
• There must be 118-meter safety distance from
the road rail like that.
• There must be 226-meter safe distance is
required from the houses offices factories
available in the nearby.

Portable Magazine
• Mode B magazine must be approved by the chief
controller of explosives, and should have the wall of
steel plate. So, these are portable magazine.
• So, this can be moved from one place to another
place.
• So, that is why this will be made of steel plate of at
least 5 mm thick. Roof is also of similar 5 mm thick.
Interior lining must be of 10 mm thick on walls doors
ceilings with wood fitting boards or woods as you
have observed in the video.

Portable Magazine
• In this type of magazine, you must provide 0.65-meter
cube of interior space for 100 kgs of explosive.
• You can observe this is little bit higher than the earlier
one. The reason is that the it is made of steel plates.
• So, the internal temperature may arises maybe rises
more than the concrete type of magazine. And
maximum volume shall not exceed 2-meter cube in the
inside the per 100 kgs of explosive.
• And there will be no iron or steel exposed to the
interior. So, that explosive may come in contact with
that.
• it will be on a raised ground, and maintain a minimum
safety distance of 95 meter from all houses and
buildings, and 50 meter from public roads, railway
tracks etcetera

Underground Magazine
• As per CMR, MMR, that is the coal mine regulation and
metal mine regulation. As it is written explosives shall
not be stored belowground in a mine, except with the
approval of in writing of chief inspector of mines, and
subject to such condition as he may specify therein.
Such storage shall be done only in a magazine or
magazines duly licensed in accordance with the
provision of the rules made under explosive act 1884 .
so on
• This provision may allow to store explosives for 3-4
week’s requirement.
• This may avoid the issue and return of explosives at the
beginning and end of each shift to the main magazine.

Underground Magazine
• This also requires magazine in charge/keeper
in all the three shifts in underground.
• Chances of pilferage of explosives enroute the
magazine and mine is eliminated.
• Instead of carrying explosives in every shift, on
weekly rest days bulk of the requirement
could be transferred through the cage.

Reserve Station
• Reserve station is also another type of storage
place is of temporary in nature.
• This is a temporary storage place of explosive in
the underground.
• The places in the underground working identified
by the manager for the purpose of keeping
temporary storing of explosive; that means, if
there is no underground magazine, the explosive
is taken from the surface, then through cage the
explosives are transferred to the underground.

Reserve Station
• Such places are not frequently visited by work
personnel.
• Roof is dressed properly of any overhangs.
• Properly fenced and contains a sign board stating
“Reserve Station”
• They are meant for keeping the securely locked
explosives (in container) and detonator boxes
(wooden) issued to the shotfirer/blaster for use during
the shift only.
• it must be white washed. So, that the visibility is very
high.
• Before the end of the shift hours, the explosives
remaining in the reserve station must be taken out to
the surface.

Transportation of Explosives
• Transportation of explosive is carried out twice, from
the manufacturer site to the users magazine, and
users magazine to the site of use.
• As per explosive rule transportation can be carried
out by a road van or by a railway wagon.
• The carrying capacity for the road van is 10 ton
maximum or the van load whichever is the less.
• The carrying capacity for railway wagon it is 10 ton
or half of the maximum wagon, wagon load
whichever is the less.
• Same vehicle cannot be used for transporting the
explosive and detonators.

Transportation of Explosives
• If required special vehicles may be manufactured
where the separate compartments are there for the
explosive and detonators not more than 200
detonators are transported at a time.
• Explosive and detonator should have their original
casing during the transportation. So, it is not that, it
has to be taken out from the original casing and placed
in some other casing.
• Vehicle maximum speed should not exceed 20
kilometer per hour.
• For transporting the explosives in the underground
drive, drift, and stope a person in his felt back can take
maximum 25 kgs.
• The person must be a blaster or blasting crew
members which is a competent person.

Impact Testing
• The impact testing of explosives is performed by dropping a
fixed weight onto a prepared sample of the explosive to be
tested from a given distance.
• The weight is released, impacts upon the sample, and the
result is noted.
• The impact distances are determined and the results are
analyzed by the sensitivity test and analysis methods
selected.
• The two most common sensitivity test and analysis
methods are the Bruceton analysis and Neyer d-optimal
test.
• These methods allow the user to determine the 50%
initiation level (the distance at which 50% of the samples
will "go"), and a standard deviation.
• Impact testing may also be performed with liquid samples
confined in special cells.

Friction Testing
• There are several techniques through which explosives
may be tested to determine their sensitivity to friction.
• One of the most popular is the ABL friction test, which
uses a line of explosives on a prepared metal plate,
placed in front of a specially prepared metal wheel that
is forced down upon the plate with a hydraulic press.
• The metal plate is then struck with a pendulum to
move it, squeezing the explosives between plate and
wheel as the plate moves. Initiation is determined, and
analyzed by the Bruceton analysis or Neyer d-optimal
test, as above. BAM friction testing is similar, except
that the sample is placed on a ceramic plate which is
then moved side-to-side as a ceramic peg exerts force
on the sample.

Electrostatic Testing
• Testing for ESD, or spark sensitivity of explosives
is performed with a machine designed to
discharge from a capacitor through a prepared
sample.
• The Sandia National Labs design employs a
dipping needle that punctures a sample cell and
discharges the spark simultaneously.
• The amount of energy discharged into the cell
becomes the variable in which Bruceton
analysis or Neyer d-optimal test is performed to
determine spark sensitivity.

Thermal Sensitivity
• Determining the point at which a compound is capable of
detonating under confinement with thermal stress is useful.
• A fixed quantity of material is placed in an aluminum blasting cap
shell, and pressed into place with an aluminum plug.
• The sample is immersed in a hot metal bath, and the time-to-
detonation is measured. If over 60 seconds, a fresh sample is run
again at a higher temperature. In this manner, it is possible to
determine the temperature at which an explosive will detonate on
the small scale.
• Unlike the other tests above, this figure is misleading as explosives
have more thermal issues on the large scale.
• Therefore, the thermal sensitivity figures established using this
technique are higher than one would expect in the real world.
• Thermal safety testing may also be performed via differential
scanning calorimetry, in which a small (sub-milligram) sample is
placed in a sample cell, and the temperature is increased slowly.
• The calorimeter determines how much energy is required to
increase the temperature of the sample. Using this device,
characteristics such as the melting point, phase transitions and
decomposition temperature of an explosive may be determined.

Classification of Explosives Initiating Device

Safety Fuse
• It is used to ignite low
explosives and detonator
to initiate high explosives.
• It has a core of black
powder tightly wrapped
with various layers of
water proof textile
yarn/tape.
• It has inaccurate timing,
poor fragmentation, poor
safety
• Safety fuse burns at a rate
of 120 seconds per metre.

Detonating cord
• Safety fuse burns but detonating cord
detonates.
• It gets initiated by a detonator and in turns
propagates to shock wave to the explosive
column.
• It detonates at a rate of 7000 m/s. A
detonating cord is carrier of detonating wave
which is used to detonate the primer.
• It has a core of PETN (varying from 3 to 80
g/m), wrapped in a plastic tape/nylon cord
layer, textile layer and finally covering to give
strength of 50 to 60 kg.
• There are many uses of detonating cord
including production blasting to fire main
shots, pre-splitting, smooth blasting etc.
• It is insensitive to shock and flame.

Plain Detonator
• A plain detonator
consists of an
aluminium tube (32-
50) mm long and 6.5
mm in diameter
which contains an
explosive charge
pressed in the
bottom of the tube.

Ordinary Electric Detonator
• Electric detonators are used to initiate other explosive,
detonating cord and shock tube
• In electric detonators electric energy is sent through copper
leg wire to heat an internal connecting bridge wire.
• Electric detonators It looks the same as the plain
detonators but the only difference is the two leg wires
attached to the detonators.
• Most of the detonators has the resistance of 1 to 2 ohms
and the current needed to detonate the detonators is 1.5
amperes.
• There are two types of electric detonators which are the
instantaneous type and the delay type.
• The instantaneous will detonate at zero second upon
initiation.
• The delay detonators are manufactured in the same way as
the instantaneous but the only difference is the presence of
a delay element.

Low Tension Electric Detonator
Brass foils having unequal length. Brass
foils are connected through NI-Cr wire
bridge. Flashing mixture consists of
mixture of LMNR, Potassium Chlorate,
Charcoal, Colloidal Cotton. Current
required is 0.5 amp for igniting the fuse
head. Voltage required is 3.5 V. Internal
resistance of leading wire is less than 1
ohm. Total resistance is required 7 ohm
including 45 m shot firing cable. Base
charge is PETN and Prime charge is ASA.
It can be used in series connection with
each other.

High Tension Electric Detonator
Brass foils having equal length. Brass
foils are not connected with each
other. Flashing mixture consists of
LMNR, Potassium Chlorate, Charcoal,
Nitro Cellulose, Copper Acetylide and
Graphite Powder. Graphite is a good
conductor of electricity. Graphite
powder acts as chemical bridge
between the ends of brass foil. Internal
resistance including leading wire
ranges from 1000 to 30000 ohm.
Minimum current required is 0.025
amp. Minimum voltage required 50 V.
Circuit continuity test can not be done
for this detonator. Chances of short
circuit if connected in series.

Electric Delay Detonator
• Electric delay detonators series are:
• Half second series: The range of delays
available is 1 to 12 giving a total of 12
detonators in series, where a half second
interval between each delay.
• Millisecond series : Basically 25 ms delay time
interval.
• Carrick short delay series : These detonators
complemented the permitted explosives and
are specially designed for use in coal mines
Structure of a typical electric detonator

Electric Delay Detonator
Ordinary Electric Detonator

Comparison between Electric and electric delay detonator
Ordinary Electric Detonator Electric Delay Detonator

Pyrotechnic and Electronic Delay

Electronic Detonator
• Electronic detonator have an electronic counter
on a microchip in place of pyrotechnic delay
charge.
• Advantages:
• Higher timing precision (10 microsecond than 1-
10 ms scatter)
• Increase control time delay greater safety against
accidental ignition (coded firing signals)
• Disadvantages
• Higher price because of chip and capacitor
• Back to electric wiring-risk of ground faults or
poor contacts

NONEL
• The invention of a shock tube or signal tube is basically a modern
version of safety fuse, where a flame can travel through the center of
the tube.
• The tube is made of plastic with 3mm OD and 2mm ID.
• An explosive powder called HMX covered the inside surface of the
tube.
• The powder detonates at a velocity of about 2000 m/s and this sends a
detonating wave to the detonator.
• The plastic tube is not destroyed after detonation of the explosive
powder.
• The tube can only be initiated by a detonator or by a Nonel exploder.
• Its usage is more appropriate in areas where electric detonators are
not advisable to be used.
• The detonator which present in the hole with booster is called as down
the hole.
• NONELs are available in 100 to 150 millisecond.
• It consists of non electric detonator at one end and the other end also
connected with same detonator which is used to join the line.

Nonel
• Non-electric initiation systems
include a cap similar to that of
an electric cap, but they are
connected to plastic tubing or a
transmission line that carries an
initiation (shock and heat) to
initiate the cap.
• Not used in underground coal or
gassy mines.
• Provide nearly infinite numbers
of delays in blasting patterns.
• Delays are available in short and
long periods as well as in-hole
and surface delays.
• It is made up off 14 -16
milligram of PETN or TNT per
meter length.

Relay Connector
• Relay connectors are blasting delay elements
primarily for use in surface mining and quarrying
operations.
• There are two main types: 1)Detonating relay
connectors(DRC) 2)Nonel trunk line delays(TLD)
• A DRC consists of two delay detonators, of from 5
millisecond (ms) to 60 ms duration. The complete
unit is in the shape of a sealed plastic dog bone.
• The DRC is inserted at an appropriate position in
the detonating cord line .

Trunk Line Delay
• A TLD unit consists of a plastic “bunch block”
connector which houses a Nonel delay
detonator attached to a length of signal tube.
The delay periods vary, depending on the
particular manufacturer’s product.
• The relay type of each TLD, which functions
unidirectionally, ensures true hole-by-hole
initiation with correct sequencing.

Exploder
• Exploders or blasting machines are used in the electrical
initiation system.
• These are available depending on the number of electric
detonators in the circuit. The common range is for 1, 12, 25
30 and 100 detonators.
• Some exploders are compound-wound generator types,
whereas others are battery operated capacitor-discharge
types.
• A type of dynamo-condenser exploder can fire 100
detonators in series. This is a hand-driven generator
together with a condenser is incorporated in this exploder.
• A neon lamps indicates when the condenser is charged
with a least 1200 volts AC, and a button switch applies the
voltage from the condenser to the output terminals.
Exploder

Exploder
There are three types of exploder used in Indian mines i.e.
1. Magneto (or Dynamo) Exploder
2. Battery condenser Exploder
3.Condenser dynamo Exploder
The exploder can be so constructed that:
• It shall be operated by a removable handle or key.
• The firing circuit is made or broken either automatically or
by the operation of handle or key or a push button switch.
• No residual energy is left at the terminals after the
completion of operation sequence.
• The permitted type exploders shall have suitable devices so
as to terminate the output energy pulse within four
milliseconds of the operation of the firing switch/key. All
exploders must incorporates circuit testing facilities to be
used in mines.

Magneto Exploder
• The magneto exploder consists essentially of a permanent
steel magnet between the poles of which revolves an
armature rotated through gearing by rotary handle or by a
rack and pinion.
• The value of the voltage depends upon the speed at which
the armature revolves and the flux created by the magnets.
• A low tension exploder gives a voltage of about 15 volts.
• A high tension exploder gives about 125 volts.
• The magneto exploder fires only 1 or 2 shots at a time with
single shot exploder and up to 6 shots in series with a 6-shot
exploder.
• The exploder for U/G coal mines should be intrinsically safe.
The armature is actuated by a special twist action detachable
key which should always be with the shot firer.

Battery Exploder
• In this type of exploders four or six dry primary cells are used.
These dry primary cells are connected in series. The e.m.f. of
each primary cell is 1.5 volt. The exploder has a detachable
key.
• When this is fitted and rotated through half wind, the shaft
winds the spring against the spring action. The shaft is
provided with governor contact. The governor contact can
make or break electric circuit.
• One terminal of series connection of cell is connected to
terminal point T1 and other terminal of series connect is
connected to T2 terminal point through a contact plug. T1 and
T2 terminals are outside to connect the blasting cable.

Battery Exploder
• The contact plug is operated by governor contact. After half
the wind of key when it is released its shaft is rotated at fast
speed by the unwinding spring.
• Due to high speed rotation of shaft the governor contact flies
away and plug contact is made.
• At this time the current is supplied to terminal point T1 and T2
so the current will flow through the detonators and will be
blasted.

Dynamo Condenser Exploder
• A small strong dynamo contains thin Cu wire armature winding.
• This armature winding is rotated in the earth magnetic field at
high speed to generate the strong induced electric current. This
current is used for the blasting purposes.
• The principle of working of dynamo is nearly similar to the
magneto type of exploder.
• These exploders are also provided with condenser circuit with
indicator bulb and push button switch.
• When the armature windings are rotated through rack and
pinion at high speed it generates the required current and
voltage and the condenser gets charged. When the condenser
is fully charged the indicator bulbs starts glowing.

Dynamo Condenser Exploder
• The further rotation of armature is stopped after removing
the handle or key. The push button is provided on the
exploder and T1 and T2 contact point. The T1 and T2 contact
points are connected to blasting cabling.
• When the push button is pressed the condenser gets
discharged and electric current flows through the blasting
cable.
• So the detonators connected in the circuit will be blasted

Circuit Continuity Tester
• Before firing the detonators with exploder, it is required to
check the continuity of the firing circuit with a resistance
measuring device.
• It is better to measure the circuit resistance to be of the
order for the particular number of shots.
• If the resistance is high and the firing is continued there
may be misfire. To avoid this, there should be a check over
the measurement of continuity and circuit resistance.
• While doing so the testing current in the circuit should be
as low as possible not exceeding 50 mA so that the
detonators may not be fired while checking the continuity
of shots. The circuit of the continuity tester shall be
intrinsically safe.

Circuit Continuity Tester
• The instrument shall be so designed and constructed as to be
incapable of firing even a single detonator in the circuit.
• The construction and the enclosure of the continuity tester shall
meet the similar requirements as applicable to exploders.

Detonators are connected in series

Detonators are connected in Parallel

Question-1
Match the following for a typical slurry explosive
(A) P-1, Q-2, R-3, S-4
(B) P-2, Q-4, R-3, S-1
(C) P-3, Q-1, R-4, S-2
(D) P-4, Q-3, R-2, S-1
Chemical Purpose
P. Calcium Nitrate 1. Cross linking agent
Q. Potassium dichromate 2. Gelling agent
R. TNT 3. Oxidiser
S. Starch 4. Fuel

Question-2
• The weight strength of ANFO of specific gravity
0.8 is 912 kcal/kg. The weight strength of an
emulsion explosive of specific gravity 1.2 is 850
kcal/kg. Bulk strength of the emulsion explosive
relative to ANFO in percentage is ------

Question-3
• If you encounter blast holes that are wet, which
product(s) should you use (list all that apply)?
A. Gun powder
B. 20-percentemulsion/80-percent ANFO blend
C. 100-percent ANFO
D. Emulsion

Question-4
Cap-sensitive explosives are classified as:
A. Wet blasting agents
B. High explosives
C. Low explosives
D. Ammonium nitrate

Question-5
• Reddish-orange smoke after a blast signifies
the presence of:
A. Carbon monoxide
B. Water vapour
C. A good blast
D. Oxides of nitrogen

Question-6
• For a delay blasting of 10 circuits, a sequential
timer is set on 25 ms between circuit
initiations. If the nominal firing time of a
detonator is 400 ms, the last hole will be
blasted at ----- ms.

Question-7
• Based on classification of explosives as per explosives rules,
choose the correct combination
Category Explosives
P. Class-1 1. Nitro compound
Q. Class-2 2. Chlorate mixture
R. Class-3 3. Nitrate mixture
S. Class-4 4. Gun powder
(A) P-1, Q-2, R-4, S-3
(B) P-4, Q-2, R-1, S-3
(C) P-4, Q-3, R-1, S-2
(D) P-1, Q-3, R-4, S-2

Question-8
(A) P-3, Q-1, R-4, S-2
(B) P-4, Q-2, R-1, S-3
(C) P-4, Q-3, R-1, S-2
(D) P-1, Q-3, R-4, S-2
Blasting Elements Initiators
P. Electric Detonator 1. Match Stick
Q. Safety Fuse 2. Booster
R. Detonating Fuse 3. Exploder
S. Non Cap sensitive explosive 4. Ordinary Detonator

Question-8
• Deflagration is
A. Rapid explosion
B. Burning and explosion
C. Rapid burning but not an explosion
D. Change in the inclination of the drill hole

Question -9
• Which property is, in general, not evaluated
for an explosive
A. Velocity of detonation (mm/s)
B. Density (g/cc)
C. Compressive strength(MPa)
D. Weight strength (J/g)

Question-10
• Find the voltage required to fire 30 electric
detonators joined to 200 meters of firing cable
with 50 meters of connecting wire. The
resistances are as follows: an average of 2
ohms per detonator, 0.1 ohm per meter of
connecting wire, and 0.05 ohm per meter for
two-core firing cable. Suppose a DC power
supply is available. Current required is 1.2
amp for the circuit.

Question-11
• Find the power requirement and the
energy input to a detonator of a parallel
circuit with 30 detonators (each with a
resistance of 1.5 ohms) with 600 m of
twin core firing cable (resistance of
0.0033 ohms per m. Average current
required is 0.7 amp per detonator.

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