Note: Descriptions are shown in the official language in which they were submitted.
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"Explosive Comgrisinq a Foamed Sengitizer"
FIELD OF THE Ii~JVENTION
The present invention relates to explosive
compositions and, in particular, to sensitized explosive
compositions.
DESCRIPTION OF THE RELATED ART
Semisolid colloidal dispersions of water-bearing
explosives or blasting agents are well known. These
products typically comprise an oxidizing component, usually
predominantly ammonium nitrate, a fuel component and water.
These blasting agents are referred to in the art as slurry
explosives (or as water gels), and as emulsion-type
explosives.
Slurry explosives typically comprise a discontinuous
fuel phase which is dispersed in a continuous aqueous
solution of the oxidizer salt. Thickening agents are added
to the aqueous phase in order to increase the viscosity of
the explosive, or to effect gelation, and thus stabilize the
structure of the explosive.
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Emulsion explosives typically comprise a discontinuous
aqueous oxidizer salt solution which is dispersed in a
continuous fuel phase. Emulsifying agents are generally
added to the dispersion to stabilize the dispersion.
The addition of additives to both slurry and emulsion
explosives to modify the performance of the blasting agent
is similarly well known. These additives include, for
example, the addition of aluminum or ammonium nitrate to the
explosive to increase the strength and/or sensitivity of the
blasting agent.
Of particular interest in the present invention is the
addition of additives to create small voids within the
blasting agent, which voids can be used to control the
density of the explosive and to increase the sensitivity of
the explosive. These sensitized explosives were described,
for example, by Cattermole g~ ~ in U.S. Patent No.
3,674,578: Bluhm in U.S. Patent No. 3,447,978: Wade in U.S.
Patent No. 4,110,134 and Clay in U.S. Patent No. 4,181,546.
One method of addition of voids fn a blasting agent is
the addition of hollow glass microballoons to an emulsion
explosive. While this method provides a suitable means for
the creation of voids within the blasting agent, the
microballoons are relatively expensive and can be difficult
to handle due to their low bulk density.
The use of similar products to microballoons which
products also have particles containing one or a number of
gas bubbles, such as, for example, inorganic hollow
microspheres made of glass, sirasu (Japanese volcanic ash),
silicon sand, or sodium silicate and the like, is also
known. These materials suffer from the same disadvantages
as glass microballoons.
Edamura et ~ disclose in U.S. Patent No. 4,543,137,
the use of a gas-retaining agent, such as, those made from
foamed polystyrene, foamed polyurethane and the like. The
gas-retaining agents of Edamura gt ~ can have a rigid
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structure similar to the inorganic microballoons described
hereinabove, and which can be brittle and subject to
breakage during handling or can be made soft and spongy so
as to be more resistant to inadvertent breakage during '
handling.
These soft and spongy gas-retaining agents are produced
by foaming a foaming agent in a thermoplastic resin and
allowing the thermoplastic resin to set and thus entrap gas
within the resin structure.
However, this route of adding gas voids to the blasting
agent requires the initial preparation of a spongy or rigid
microsphere structure which is added to the blasting agent.
In-situ generation of air or gas voids within the
blasting agent is an alternative method over the addition of
gas filled microballoons and, typically, comprises the
addition of a material which reacts in the blasting agent to
generate a gas bubble. Thie gas bubble is entrained within
the blasting agent by the viscous nature of the semisolid
blasting agent. The generation of a gas void within the
blasting agent by an in-situ chemical reaction is termed
within the industry as chemical gassing.
Chemical gassing of explosives is well known in the
slurry and emulsion explosive industry. In U.S. Patents
3,886,010 and 3,706,607, Thornley and Chrisp, respectively,
describe the use of chemical gassing agents such as
nitrites, weak acids, hydrazine and peroxides in slurry
and/or emulsion explosives.
While chemical gassing is practised in the industry,
its use is limited because of the difficulty in controlling
the reaction rate of the chemical gassing reaction. The
degree of gassing may be insufficient or may be excessively
slow under cold production temperatures and may be excessive
under hot~conditions so as to provide uncontrollable
borehole densities.
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A third route to introducing gas voids into an
explosive blasting agent is to mechanically agitate the
blasting agent composition in order to entrain an occluded
gas void within the blasting agent. This route has the
disadvantage of intensive mechanical agitation of a
sensitized explosive and can be subject to poor long-term
blasting stability as gas is slowly lost from the blasting
agent.
A further route to the production of gas voids within
an explosive blasting agent is described by Curtin and Yates
in U.K. Patent Application No. 2,179,035, wherein a gas
bubble generating agent is added to the blasting agent prior
to or while the blasting agent is subjected to super-
atmospheric pressure to dissolve at least part of the gas
present. The blasting agent is returned rapidly to
atmospheric pressure and, thus, creates a fine discontinuous
gaseous phase in the composition. However, this production
route requires the sensitized blasting agent to be prepared
under pressure and, thus, requires specialized equipment
adapted to handle the pressurized explosive.
In light of the problems of the gas void addition
methods of the prior art, it is an object of the present
invention to provide a slurry ox emulsion blasting agent
which is sensitized by the addition of gas voids, wherein
said gas voids are prepared and added to the blasting agent
by a route other than those routes described hereinabove.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides an
explosive composition sensitized by gas voids, wherein the
gas voids have been. distributed in said explosive
composition by dispersal of an essentially gas-in-liquid
foam.
Preferably, the explosive composition comprises an
oxidizing salt and a fuel and the explosive composition is a
slurry or emulsion explosive.
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The term "foam" in this specification and claims, is
used to describe a mass of bubbles which have been dispersed
in a liquid. The bubbles are surrounded by and, thus,
separated from each other by thin, flexible films of liquid
with, optionally, viscosity control agents or foaming agent
molecules absorbed at the gas/liquid interface in order to
stabilize the film.
Most of the volume of a foam is the gas phase and
typically, the gas phase comprises at least 90% by volume of
the foam.
The foam used in the present invention may be produced
by introducing or "sparging" a pressurized gas into a closed
vessel containing the pressurized liquid component of the
foam, mixing and subsequently releasing the pressure on the
system so as to create small gas bubbles within the liquid
component. The foam produced can then be added to and
blended into the base explosive composition by, for example,
a low shear or a static mixer,
The pressurized gas used to form the foam can be any
gas which is compatible with other components of the
explosive. Preferably, the gas is air, carbon dioxide or
nitrogen but any other gas could be used provided that the
solubility of the gas in the liquid is controllable over the
time and temperature range to which the sensitized explosive
will be stored prior to use.
Bubbles can also be dispersed in the liquid carrier to
produce a foam by mechanical agitation, such as, for
example, by a high shear mixer, such as an Oakes mixer, or
by low shear mixing of the liquid carrier to entrain gas
voids within the liquid carrier. Mechanical agitation in
the process of the present invention is, preferably,
conducted on a non-explosive liquid carrier and, thus, is
inherently safer and more effective than a process of
entraining gas voids directly into the explosive
composition.
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The foams of the present invention, preferably, have a
low density in order to effectively lower the density of the
explosive to which the foam is added. Preferably, the foam
has a density of less than O.lg/ml and, even more
preferably, below 0.06g/ml.
As soon as a foam is created, the liquid phase which
surrounds the individual bubbles will begin to drain so as
to create a thinner layer at the top of the bubble than at
the bottom. Eventually, the thinner layer will break
causing coalescence of the bubble or loss of gas from the
foam and the loss or drainage of the carrier liquid from the
foam. The loss of gas is, thus, related to the 'drainage'
rate of the foam in that the gas volume is reduced as liquid
drains from the foam. The stability of the foam can, thus,
be measured by determining the half-life of the foam wherein
the half-life is the time taken for the loss of half of the
gas volume from the foam. The half-life is, thus, an
indication of the shelf life of the foam after the foam is
produced.
Control of the drainage rate and, thus, control of the
half-life of the foam can be influenced and effectively
controlled by the addition to the foam of additives which
stabilize the liquid film around the bubble. If the foam is
to be incorporated in the explosive shortly after it is
produced, for example, within one to four minutes of
production, foam stability is not as critical as for foams
which are prepared and later added to the explosives.
Additives, such as high viscosity polyisobutylene, act
to increase the viscosity of the liquid film around the gas
bubble. Further, additional additives, such as foaming
agents are, preferably, added to the liquid carrier in order
to assist in formation of the foam.
Accordingly, the foams of the present invention,
preferably, comprise a gas, a foaming agent, a viscosity
control agent and a liquid carrier.
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The foaming agent provides a film around the gas
bubbles in order to prevent them from bursting or .
coalescing. Typical foaming agents would include materials
such as proteins, and, more specifically, milk proteins, egg
proteins, animal proteins, vegetable proteins, fish
proteins, and any mixture thereof. The foaming agent can
also be a protein derivative or associated product, such as,
phospholipids, lipoproteins, collagens, hydrolyzed proteins,
and globulins. Steroids may also be used as a foaming
agent.
The foaming agent may also include surfactants, such
as, for example, FC?40* or FC?51,*, which are perfluorinated
surfactants, or mixtures of other surfactants. other
foaming agents include lanolin oil, derivatives of succinic
anhydride, glycerol monostearate, steryl octazylene
phosphate and long chain alcohols.
Casein is a mixture of proteins extracted from milk
solids or soya beans, and can be used as is or can be
fractionated into a water soluble portion or an oil soluble
portion, each of which can be separately used as a foaming
agent. The casein used may be totally or partially soluble
in the oil but is, generally, dispersible so as to not be
detrimental to foam production.
The stability of the foam may also be enhanced by the
addition of solid particles, such as, carbon black, talc or
other materials known in the foam stabilization art.
Viscosity in the foam can be controlled by the addition
of viscosity control agent materials, such as, for example,
high viscosity polyisobutylene, butyl rubber, natural
gibber, bifunctional high molecular weight acids and the
like and mixtures thereof to the liquid carrier which will
increase the viscosity of the liquid component of the foam.
Excessively high viscosity in the liquid component of
the foam, however, is not desirable since the high viscosity
will make preparation of the foam difficult. Thus, an
* Trade Mark
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optimum level of viscosity control agent is required in
order to ensure that the drainage rate of the foam is low,
but that the foam is relatively easy to produce.
In an oil-based foam, the viscosity of the oil selected
will also influence the ease with which the foam can be
produced and the drainage rate of the foam. Selection of
the oil will, thus, depend on, inter alia, the method of
manufacture of the foam, mixing conditions, temperature,
residence times, pressure, type of gas and the like.
The foam can be added to sensitize any suitable
explosive material wherein gas voids are advantageous.
Explosive materials include, in particular, emulsion or
slurry explosives but also include propellants, high heave
explosives, such as, heavy ANFO, modified emulsions, cast
explosives, nitro ester based systems, and TNT, RDX or N6
based systems.
The liquid carrier used to prepare the foam is a liquid
which is, preferably, compatible with the continuous phase
of the explosive and into which the preferred additives of
the foaming system can be dispersed or dissolved. The
liquid carrier may take part in the detonation as a fuel or
comprise an oxidizer, a sensitizer, or it may be
non-reacting.
In a slurry explosive, water miscible liquids are
preferred. In particular, the most preferred liquid for
slurry explosives is water as a solvent or dispersion medium
for desired additives or solutes.
For an emulsion explosive, preferred liquids are
non-aqueous oils and solvents which are miscible with the
organic liquid phase. Most preferred, however, are liquids
or liquifiable materials which act as fuels in the explosive
reaction. Typically, fuels include, for example, paraffin
oil and fuel oil. However, the liquid carrier need not be
perfectly compatible with the continuous phase of the
explosive provided that the explosive composition created
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remains sufficiently stable to allow adequate storage
stability based on the proposed use of the explosive
composition.
Emulsion explosives includes low and essentially
non-aqueous emulsions.
The liquid carrier will, preferably, contribute to the
total fuel phase present in the emulsion explosive and,
thus, may be described as a fuel for the explosive, as
described hereinabove. In the preparation of the foam,
however, it is desirable to minimize the amount of liquid
used in the production of the foam in order to maximize the
amount of liquid which is available for pre-formation of the
base emulsion explosive.
The use of a non-aqueous liquid in a slurry explosive
may also provide fuel value to the explosive composition.
With the selection of a liquid carrier of a suitable
viscosity, such as, for example, high viscosity paraffin
oil, the use of a viscosity control agent can also be
reduced or eliminated.
Accordingly, the present invention provides a gassed
explosive composition as described hereinabove wherein the
gassing is achieved by a dispersed pre-formed foam and of
which the liquid in said gas-in-liquid foam comprises a
liquid or liquifiable fuel and a foaming agent.
When the liquid carrier is water, it is preferable to
add a material to the water which acts as a freezing point
depressant and, thus, make the base explosive composition
and/or the foam, to which the foam has been added, more
stable in cold temperatures. A preferred freezing point
depressant is ammonium nitrate. However, low-freezing
point, water miscible liquids or liquid mixtures, such as,
ethylene glycol and water can be used as a liquid carrier in
place of .water. The foam, once produced, is added to a base
explosive composition, which base explosive composition is
an insufficiently or non-sensitized emulsion or slurry
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explosive. The foam is, preferably, added to the base
explosive composition shortly after its production, in order
to minimize the need to create foams which are stable for
long periods of time. It has been our experience that the
use of foams having a half life of greater than one to four
minutes is desirable in order to have sufficient time to mix
the foam into the explosive composition.
The foam is, preferably, added to the base explosive
composition by a low shear mixing technique, such as, a
static mixer or a ribbon mixer. During addition of the
foam, the foam is broken and its gas bubbles are merely
dispersed within the base explosive composition. At this
stage, there is generally no need for intense mechanical
agitation to entrain additional gas voids within the
explosive composition.
The present invention, thus, provides an explosive as
described hereinabove wherein the explosive composition is
an emulsion explosive. Preferably, the liquid carrier used
to prepare the gas-in-liquid foam, which is to be added to
the emulsion explosive, is a fuel.
Further, the present invention also provides an
explosive as described hereinabove wherein the explosive
composition is a slurry explosive and, preferably, the
liquid carrier used to prepare the gas-in-liquid foam, which
is to be added to the slurry explosive, is water.
The base explosive composition to which the foam
sensitizes is added can be any chemically compatible
emulsion or slurry explosive, which base explosive
compositions are described in the prior art. These base
explosive compositions generally consist of an oil-in-water
or water-in-oil dispersion of an aqueous solution of an
oxidizing salt and a fuel.
The. oxidizing salt may be any of the oxygen-containing
salts typically used in the industry. These salts include,
for example, nitrates, chlorates, and perchlorates. Most
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preferred, are salts, such as, sodium nitrate, calcium
nitrate, potassium nitrate, and, most preferably, ammonium
nitrate or mixtures thereof. In slurry explosives, the
oxidizing salt is dissolved in water to provide the
continuous phase of the explosive composition. For an
emulsion explosive, the oxidizing salt may be melted, (e. g.
as an eutectic mixture) to provide a liquid which can be
dispersed as a discontinuous phase into the fuel or, more
preferably, may be dispersed into the fuel as a concentrated
aqueous solution.
The fuel phase may be any liquid or liquifiable fuel
known within the explosives art and may be the same as or
different than the fuel used in the preparation of the foam.
Suitable materials include mineral oil, waxes, paraffin
oils, benzene, toluene, xylenes, and mixtures of petroleum
distillates such as gasoline, kerosene and diesel fuel.
An emulsion explosive formed as an embodiment of the
present invention, preferably, also include stabilizing
surfactants, such as, for example, a mixture of sorbitan
sesquioleate and a polyisobutylene succinic anhydride
(PIBSA) based surfactant. These PIBSA based surfactants are
described in Canadian Patent No. 1,244,463 (Baker).
However, any surfactant of use in the emulsion explosive art
may be used to prepare the emulsion to be used in the
present invention.
Many suitable conventional emulsifiers have been
described in detail in the literature and include, for
example, soribitan esters, such as, sorbitan sesquioleate,
sorbitan mono-oleate, sorbitan mono-almitate, sorbitan
mono-stearate and sorbitan tristearate, the mono- and
di-glycerides of fat-forming fatty acids, Soya bean lecithin
and derivatives of lanolin, such as, isopropyl esters of
lanolin fatty acids, mixtures of higher molecular weight
fatty alcohols and wax estes, ethoxylated fatty ethers, such
as, polyoxyethylene lauryl ether, polyoxyethylene oleyl
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ether, polyoxyethylene stearyl ether, polyoxyalkylene oleyl
laurate, and subsituted oxazolines, such as, 2-oleyl-4,4'-
bis-(hydroxymethyl)-2-oxazolines. Suitable mixtures of such
conventional emulsifiers may also be selected for use,
together with one or more modifiers, in the compositions of
the present invention.
Accordingly, the present invention provides an emulsion
explosive comprising a continuous fuel phase, a
discontinuous oxidizer phase and a surfactant for
stabilization of said emulsion which emulsion has been
sensitized by the addition of a gas-in-liquid foam.
The slurry explosives formed as an embodiment of the
present invention, preferably, also include viscosity
controlling additives, such as, for example, guar in order
to increase to viscosity of the explosives so as to entrain
the gas voids from the foam in the sensitized explosive
formed.
The explosive compositions of the present invention may
also comprise additional additives to enhance or modify the
properties of the explosive blasting agent. The use of
these additives is commonly known within the explosives
industry and include the solid dopes and sensitizers
commonly added to emulsions, such as, aluminum,
ferrosilicon, TNT, AN, MAN, PETN and the like. Further,
additional sensitizing agents, such as, for example, glass
microballoons, may also be used in combination with the
foams of the present invention.
In a further aspect, the present invention also
provides a method of manufacturing a sensitized explosive
composition comprising:
preparing a base explosive composition by emulsifying
an aqueous solution of an oxidizer salt in a liquid or
liquifiable fuel, or by emulsifying a liquid or liquifiable
fuel in an aqueous solution of an oxidizer salt:
preparing an essentially gas-in-liquid foam by mixing a
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carrier liquid with a foaming agent to form a foaming
solution and subjecting said solution to mechanical
agitation, such as in a high shear mixer, low shear, or a
static mixer, or other mixers known to those skllled in the
art of foam manufacture, or to a pressurized gas sparge, or
allowing it to foam by chemical reaction in the foam system,
and
blending said gas-in-liquid foam into said base
explosive composition.
In a still yet further aspect, the present invention
also provides a method of blasting which comprises placing
an explosive detonator in operative contact with an
explosive and detonating said detonator.
EXAMPLES
The invention will now be described by way of example
only, with reference to the following examples.
EXAMPLE 1
A fuel (or oil) based foaming solution was prepared
having the composition shown in Table 1. All percentage
figures shown are percent by weight unless otherwise
indicated.
SABLE 1: Oil Based Foaming Solution
Liquid carrier Paraffin oil 89.5%
Foaming agent Casein 1.5
Foaming agent FC740* 3.0
Viscosity control agent Polyisobutylene 6.0
100.0
*Perfluorinated surfactant and bubble stabilizer
A foam was produced by sparging the foaming solution
with a pressuring stream of nitrogen gas. A foam was
produced having a gas volume of greater than 90% by volume
and a half life of greater than one hour.
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EXAMPLE 2
A water based foaming solution was prepared having the
composition as shown in Table 2.
TABLE 2: Water Based Foaming Solution
Liquid carrier Water 69.0%
Freezing point Depressant Ammonium nitrate 25.0
Foaming agent FC751* 3.0
Foaming agent Casein (water soluble) 3.0
100.00
*A short chain perfluorinated amine ester
mixture surfactant and bubble stabilizer
A foam was produced by mechanically agitating the
foaming solution in a high shear mixer. A foam was produced
having a gas volume of greater than 90% by volume and a half
life of greater than one hour.
EXAMPLE 3 - 6
Emulsion explosive compositions comprising an oil based
foam were prepared according to the present invention,
having the formulations set out in Table 3. In each
example, the foam was prepared according to the method and
formulation as set out in Example 1.
The oxidizer salt used in these examples was ammonium
nitrate or an ammonium nitrate/sodium nitrate mixture.
Paraffin oil was used for the oil phase in each
example and a sufficient amount was added to produce a
sensitized emulsion explasive with a 5% total oil phase.
The total oil phase includes surfactants.
In each example, the oxidizer salt solution was added
to the oil phase containing a PIBSA based surfactant and
sorbitan sesquioleate mixture while mixing in order to
produce an emulsion explosive. Examples 3 and 4 were
prepared using low shear mixing and Examples 5 and 6 were
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prepared by high shear mixing. The foam was dispersed into
the emulsion by low shear mixing.
The sensitized emulsion for each example was placed
into a 25 or 50 mm cartridge in order to test the blasting
ability of the explosive.
The blasting ability of each composition was measured
by determining the cap size needed to detonate the
composition. Thus, in Table 3 under blast results, the cap
size used and the blast result for each example is shown.
Where measured, the velocity of detonation (VOD) for a
successful blast is indicated.
Examples 3 and 4 are typical of products which would be
sold as "bulk" blasting agents and, thus, cap sensitivity is
not expected. Examples 5 and 6 are typical of packaged
products and cap sensitivity may be desirable. In all
examples, explosives could be prepared using the foam
sensitizer which had acceptable sensitivity for industrial
use.
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~ABLE 3: Blasting Results of Foamed Explosives
$last Results4
Example AN/water~ 2.3g PETN/4811 m/s4
3
Oil phase2
Foam 3.3%
Density = 1.07 g/ml
50 mm diameter
Example AN/water~ 0.78g/3800 m/s
4
Oil phase2 2.3g/4790 m/s
Foam 3.4%
Density = 1.07
50 mm diameter
Example AN/SN/watp~r3
Oil phase 0.2g VOD 4100 m/s
Foam 3.7%
Density 1.13
25 mm diameter
Example AN/SN/wat~r3 0.3g/4150 m/s
6
Oil phase
Foam 3.6% 0.2g/4050 m/s
Density 1.14
25 mm diameter
after 1 month @ 22°C 0.39/4000 m/s
after 2 months ~ 22°C 0.3/4100 m/s
after 3 months C 22°C 0.3/3950 m/s
~An 81/19 mixture by weight of ammonium nitrate
and water having a Fudge point of about 60°C.
ZParaffin oil (4% of total explosive weight), a PIBSA based
surfactant (0.66) and sorbitan sesqufoleate (0.34%)
mixture was added to prepare an emulsion explosive having
a total oil phase of 5%.
3A 77/11/12 mixture by weight of ammonium nitrate,
sodium nitrate, and water having a Fudge point of
about 75°C.
Blast results are shown as grams of PETN in the detonator
used for detonation, and the VOD for the resultant
explosion.
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Stability of the product produced was measured by
storing the explosive composition of Example 6 for 3 months.
As is shown in Table 3, the composition had an acceptable
VOD after 3 months storage at 22'C.
EXAMPLE 7
A "doped" emulsion explosive which was sensitized by
an oil based foam, which foam was prepared as in Example 2,
was prepared having the following formulation:
i. AN/SN/wat~r3
Oil phase 68%
ii. Ammonium nitrate
prills 29%
iii. Foam 3%
Density 1.18 g/ml
100 mm diameter
ZParaffin oil (4% of total explosive weight), a PIBSA
based surfactant (0.66) and sorbitan sesquioleate
(0.34%) mixture was added to prepare an emulsion
explosive having a total oil phase of 5%.
3A 77/11/12 mixture by weight of ammonium nitrate,
sodium nitrate, and water having a Fudge point
of about 75'C.
The explosive in this example was prepared by first
emulsifying in a low shear mixer the AN/SN/water mixture in
a paraffin oil and surfactant mixture. The emulsified
mixture was, subsequently, mixed with ammonium nitrate
prills to produce a doped emulsion and the oil based foam
was added to sensitize the explosive. The doped emulsion
had a VOD of 3970 m/s when initiated with a 40g Pentolite*
booster charge. The sensitivity of the doped emulsion was
industrially acceptable for larger diameter applications.
* - Trade Mark
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$XAMPLE 8
A heavy ANFO explosive which was sensitized by an oil
based foam, which foam was prepared as in Example 2, was
prepared having the following formulation:
i. AN/SN/watp~r3
oil phase 50%
ii. Ammonium nitrate
prills 47.5%
iii. Foam 2.5%
Density 1.25 g/ml
100 mm diameter
2Paraffin oil (4% of total explosive weight), a PIBSA
based surfactant (0.66) and sorbitan sesquioleate
(0.34%) mixture was added to prepare an emulsion
explosive having a total oil phase of 5%.
~A 77/11/12 mixture by weight of ammonium nitrate,
sodium nitrate, and water having a Fudge point
of about 75°C.
The explosive in this example was prepared by first
emulsifying in a low shear mixer the AN/SN/water mixture in
a paraffin oil and surfactant mixture. The emulsified
mixture was, subsequently, mixed with ammonium nitrate
prills to produce a heavy ANFO explosive and the oil based
foam was added to sensitize the explosive. The doped
emulsion had a VOD of 3300 m/s when initiated with a 4og
Pentolite booster charge. The sensitivity of the doped
emulsion was industrially acceptable for larger diameter
applications.
Having described specific embodiments of the present
invention, it will be understood that modification thereof
may be suggested to those skilled in the art and it is
intended to cover all such modifications as fall within the
scope of the appended claims.
