TECHNICAL FIELD
[0001] The present invention relates to an explosive for industrial use. More particularly,
it relates to an explosive composition that can be used for various destructive works
such as blasting, crushing, excavation, etc., in the field of civil engineering and
construction, mining operations such as quarrying, coal and other ore mining, etc.,
and operations in agricultural and forestry industries including drainage, irrigation,
grubbing and lumbering.
BACKGROUND ART
[0002] Slurry explosives and emulsion explosives are typical of the conventional hydrous
explosives. In these explosives, the active explosive components comprising an oxidizer
solution, an inflammable material and a sensitizer and the bubbles are held stably
in high concentrations in a mass in the presence of a sizing agent, and these explosives
are usually detonated by means of a detonator. In the slurry explosives, the aerated
bubbles or chemical bubbles are usually allowed to exist in the explosive composition
to let them play a role like a sensitizer, and guar gum is used as sizing agent to
compose an aqueous gel. In the emulsion explosives, an oxidizer solution and an oil
serving as an inflammable agent are combined to form a W/O type emulsion in the presence
of a surfactant serving as a sizing agent. The bubbles in these explosives comprise
glass or resinous microballoons, besides the aerated bubbles.
[0003] Use of hollow monocellular thermoplastic particles for the improvement of detonation
or the adjustment of density of these explosives is mentioned in U.S. Patent No. 3,773,573
and JP-A-54-92614 with reference to slurry explosives and in JP-A-56-100192 and JP-A-59-78994
with reference to emulsion explosives. In U.S. Patent No. 3,773,573 is disclosed a
technique for application of hollow monocellular thermoplastic particles to a wide
variety of explosives including slurry explosives, according to which the explosive
composition is heated to a temperature substantially equal to the foaming temperature
of the thermoplastic particles in the presence of the unfoamed resin particles in
the producing process of the explosive charge. However, since heating was usually
unrequired in the manufacture of slurry explosives, resin foaming in the producing
process had little practical significance. Further, even if foaming by heating in
the producing process was necessary, as understood from the explanation in JP-A-54-92614,
there has been no alternative but to employ a two-stage system in which, for the reason
of safety, a sensitizer is mixed after foaming by heating at the stage not yet added
with the sensitizer has been completed.
[0004] In these hydrous explosives, delicate adjustment of the explosive components and
the gel or emulsion structure is necessary for maintaining the detonation performance
without containing a highly sensitive agent like nitroglycerin in dynamite, and a
high-level technique is required for such adjustment. Thus, in the manufacture of
said hydrous explosives, since the explosive detonation was affected by the quality
and behavior of the explosive components through the forming process of the structure,
a great deal of time and labor have been required for the control of quality of the
starting materials and/or the control of the explosive producing conditions. As a
result, there would arise the serious problems such as frequent production of the
explosives of poor quality, which are unable to endure storage, and excessive deterioration
of detonation performance with time. Especially when the amount of the chemical foams
or the foaming agent used for the adjustment of density of the explosive composition
is increased, it not only becomes harder to obtain the intended initial performance
of the explosive but also the problem of deterioration of detonation performance with
time becomes even more serious.
[0005] Further, the slurry explosives have their peculiar gel elasticity and lack plasticity,
and when they are packed into a cartridge, such a cartridge itself proves to be soft
and limp, so that it is hard to handle and also difficulties are encountered in inserting
the cartridge into a blast hole, resulting in a reduced working efficiency for blasting
operation. Also, because of poor moldability of this type of explosives, it was hard
to use the explosives in the bare form without cartridge.
[0006] In the case of emulsion explosives, when they are given a sudden pressure, the emulsion
structure could be destroyed to lose their detonating function (this phenomenon is
called dead pressing phenomenon), and in short-delay blasting which is a normal form
of blasting operation, there would be left an unexploded residue, posing a difficult
problem for disposal thereof.
DESCRIPTION OF THE INVENTION
[0007] An object of the present invention is to provide an explosive composition which is
basically composed of an oxidizer, water and organic hollow microspheres and which
has a highly stabilized bursting performance and long-time keeping quality without
a gel or emulsion structure such as seen in the conventional hydrous explosives.
[0008] Another object of the present invention is to provide an explosive composition which
can be handled with safety, produces few unexplosed residue after blasting and is
also capable of reducing the degree of harmfulness of the produced gases.
[0009] Still another object of the present invention is to provide a low-detonation-rate
explosive having a stabilized blasting performance even in the low-density section,
which has been difficult to obtain with the conventional explosives.
[0010] The ardent researches by the present inventors for overcoming the above problems
of the conventional hydrous explosives have led to the attainment of the present invention.
[0011] Thus, the present invention provides a novel explosive composition characterized
in that a liquid phase mainly composed of an oxidizer and water and containing substantially
no viscous component is adsorbed and held on the surfaces of and/or between the organic
hollow microspheres which are an inflammable component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Fig. 1 is a microphotograph showing a fragmental fine structure of the explosive
composition according to the present invention.
[0013] Fig. 2(a) is a schematic illustration of the above structure, and (b) and (c) are
schematic illustrations of the conventional powder compositions.
BEST MODE FOR CARRYING OUT THE INVENTION
[0014] The fine structure of the explosive composition according to the present invention
can be confirmed from, for example, microphotographs. As seen from Fig. 1 which is
a typical microphotographical representation of the structure of the present explosive
composition, the composition is an aggregation of small granular bodies each comprising
an organic hollow microsphere 2 having a high-concentration oxidizer solution 1 adhering
to its periphery. A conceptual illustration of this structure is given in Fig. 2(a),
from which it is seen that in the explosive composition of this invention the organic
hollow microspheres 2 constitute the structural core of the composition. This is a
contrast to the compositional structure of the conventional slurry explosives in which,
as shown in Fig. 2(b), the aerated bubbles 5 and hollow bodies 4 are dispersed in
a gelled oxidizer/sensitizer phase 3. In the emulsion explosives, as shown in Fig.
2(c), the hollow bodies 4 such as glass microballoons are dispersed in an emulsified
oxidizer solution phase 6. It is thus obvious that the explosive composition of the
present invention is quite different from those of the conventional slurry and emulsion
explosives in form of bubbles, form of the oxidizer solution and structure of the
composition. More specifically, the composition of this invention requires no gelling
agent needed in the conventional slurry explosives and has a structure in which, unlike
the conventional slurry explosives, the bubbles are incorporated in a stable form
in the organic hollow microspheres which are an inflammable component. Also, as compared
with the emulsion explosives, the composition of this invention requires no oil phase
as an inflammable component, no surfactant for forming an emulsion and no glass microballoons
for holding the bubbles, which presents a striking contrast to the conventional emulsion
explosives.
[0015] It has been known to use the hollow monocellular thermoplastic particles in the conventional
slurry explosives, but the amount of such foams has been practically limited to about
2% at most in view of storage stability and blasting performance of the explosive
composition. In the present invention, it was found quite surprisingly that by increasing
the ratio of the organic hollow microspheres in a composition substantially consisting
of an oxidizer solution and said microspheres, it is possible to obtain an explosive
composition having a stable detonation performance even if no gelling agent, wax or
surfactant is used. Further, since said hollow microspheres can concurrently serve
as an inflammable component, it has become possible to provide an explosive with excellent
performance without necessarily requiring use of an inflammable agent such as carbon
or aluminum powder and a sensitizer mainly composed of an organic nitrate and/or an
inorganic nitrate.
[0016] It is quite remarkable that in the explosive composition of the present invention,
there takes place no separation of the liquid phase constituting principally the oxidizer
component nor visually noticeable crystal separation of the oxidizer, and a stable
structure can be maintained, so that the composition of this invention can be applied
to a variety of explosives ranging from detonator explosives to booster explosives.
Especially when the average thickness of the explosive compound layer around the organic
hollow microsphere becomes about 20 µm or less as observed by a microscope, it is
noted that the composition is even more stabilized.
[0017] The oxidizer used in the present invention can be selected from those known in the
art. Examples of such oxidizers include ammonium salts, alkali metal salts and alkaline
earth metal salts of inorganic acids such as nitric acid, chloric acid, perchloric
acid and the like, and these oxidizers can be used either singly or in combination.
Among these oxidizers, ammonium nitrate is especially recommendable as it has high
solubility in water and is also easily available. The content of the oxidizer in the
composition of the present invention is decided according to the specifications of
the explosive to be produced, but usually it is in the range of 50 to 90% by weight
based on the whole composition. When this oxidizer content is below the above-defined
range, the quantity balance between oxygen and inflammable component is tipped to
the minus side for oxygen, resulting in an increased toxicity of the gases released
after blasting. On the other hand, when said content exceeds the above range, the
blasting reactivity lowers to impair detonation propagation.
[0018] The water content in the composition of this invention is usually in the range of
3 to 20% by weight based on the whole composition. When the water content is below
this range, the solid content of the explosive composition increases to affect the
stable blasting performance thereof, while a too high water content results in a reduced
detonating performance.
[0019] The organic hollow microspheres used in the present invention are preferably those
made by using an organic high-molecular weight compound as base material. Examples
of the organic high-molecular weight compounds usable here include phenol resins,
epoxy resins, urea resins, unsaturated polyester resins, polyimides, maleic acid resins,
melamine resins, celluloses, vinyl chloride, vinylidene chloride, acrylonitrile, acrylic
acids, acrylic acid salts, acrylic esters, methacrylic acids, methacrylic acid salts,
methacrylic esters, single polymers or copolymers of styrene, ethylene, propylene,
butadiene, vinyl acetate and the like, polycarbonates, polysulfone, polyacetal, polyamides,
polyethylene oxide, polyphenylene oxide and the like. These compounds may be used
either singly or in combination. Among these organic high-molecular weight compounds,
those having thermoplasticity, such as vinylidene chloride-acrylonitrile copolymer,
vinylidene chloride-acrylonitrile-methacrylic ester copolymer, acrylonitrile-acrylic
ester copolymer and the like are especially preferred for use in carrying out the
process of the present invention. It is to be noted that the unfoamed microparticles
of a vinylidene chloride-acrylonitrile copolymer or methyl methacrylate-acrylonitrile
copolymer incorporated with a low-boiling point hydrocarbon can be easily made into
hollow microspheres by heating, so that they can be used in a heat-foamed form after
mixed with the explosive composition.
[0020] The organic hollow microspheres used in the composition of the present invention
are not specifically defined; they may be hollow spheres containing a gas or air in
the inside hollow portion or hollow bodies having closed or open spaces therein, but
hollow spherical bodies are preferred for efficiently forming the hot spots where
the explosive charge is detonated. The gas held in the organic hollow spheres may
be air, a low-boiling point hydrocarbon, other inflammable gas, or a mixture thereof.
The recommendable particle size of the organic hollow microspheres is about 1,000
µm or less in diameter. When the particle size exceeds this limit, the hot spots for
initiating explosion are reduced in number, making it difficult to produce good detonation
property. More preferably the organic hollow microspheres have a particle diameter
of 20 to 200 µm as these spheres can provide a stabilized explosion without lowering
the velocity of detonation. The film thickness of the organic hollow microspheres
is not critical; it may be properly selected as far as the film has enough strength
to give a space for accommodating the explosive composition. Usually, the film thickness
is 0.1 to 5 µm. In case the organic high-molecular weight compound forming the organic
hollow microspheres is the thermoplastic type, there are used those microspheres whose
film thickness in the foamed state is about 0.1 to 2 µm since they are required to
be capable of being foamed by heating in the explosive composition. The organic hollow
microspheres in the explosive composition of this invention are usually of a bulk
density of about 0.01 to 0.3 as measured in a dry state. The amount of the organic
hollow microspheres in the composition is usually about 2 to 15% by weight based on
the whole composition. The density of the explosive composition can be controlled
by the amount of the organic hollow microspheres. Generally, when the ratio of the
organic hollow microspheres in the composition is too low, the detonating efficiency
is lowered, and it also becomes difficult to maintain a stabilized blasting performance
for a long time. On the other hand, when the ratio of said organic hollow microspheres
is too high, the power of explosion is lowered to jeopardize the blasting reliability.
[0021] According to the present invention, it is possible to obtain an explosive composition
having a density ranging from 0.2 to 1.4 g/cm³ in a stabilized way be adjusting the
extent of foaming of the organic hollow microspheres. The explosive composition of
this invention has a velocity of detonation of usually about 1,500 to 5,500 m/sec.
[0022] In a process for preparing the explosive composition of this invention, a mixture
of an oxidizer and water is heated to a degree that will cause substantial dissolution
of the mixture, and then the organic hollow microspheres are uniformly mixed therein.
[0023] The method for heat-foaming the organic microspheres is not specified in this invention,
but the following methods may be cited as recommendable examples: ① an oxidizer, water
and the foamable organic microspheres are heated to a temperature that allows substantially
uniform mixing of said materials to form a mixed solution, and then this solution
is dropped or sprayed onto a heated plate or into an atmosphere adjusted to a temperature,
or above that, at which said microspheres are caused to begin foaming, thereby foaming
the organic microspheres contained in said mixed solution; ② an oxidizer, water and
the foamable organic microspheres are heated to a temperature allowing substantially
uniform mixing of said materials to form a mixed solution, and the solution is supplied
into a metal tube heated to a temperature, or above that, which causes start of foaming
of said microspheres, thereby foaming the organic microspheres contained in said mixed
solution; ③ a mixed solution of an oxidizer, water and the foamable organic microspheres
is put into a container and this container is heated in an external bath of a temperature
at which foaming of said microspheres takes place, thereby foaming the organic microspheres
contained in said mixed solution; ④ an oxidizer, water and the foamable organic microspheres
are uniformly mixed and heated to a temperature that allows substantially uniform
mixing of said materials to form a mixed solution, then an amount of this solution
determined by taking into consideration the volume expansion thereof (on heating)
was filled in a heat-resistant film tube, and after deairing and hermetically closing
said film tube, it was placed in a hot bath or oil bath heated to a temperature, or
above that, at which foaming of said microspheres begins, thereby foaming the organic
microspheres contained in said mixed solution; ⑤ a mixture of an oxidizer and water
is heated to cause dissolution of the best part of the solid salts to form a high-concentration
salt solution, then this solution is heated to a temperature, or above that, at which
foaming of the foamable organic microspheres takes place, and said organic microspheres
are mixed in said solution. In these methods, in case it is expected that water will
be evaporated from the composition, the amount of water that may be evaporated is
estimated and water is added in an excess amount so that the desired explosive composition
will be provided. Also, according to the process for producing the explosive composition
of this invention, it is possible to optionally change the foaming condition by adjusting
the temperature, and there can be obtained a variety of explosives ranging from the
type detonated by a booster to the type that can be detonated by a single percussion.
The unfoamed organic microspheres are increased in internal pressure by heating and
begin to foam as they are heated close to a temperature at which the organic polymer
film begins to soften, and they are expanded about 20- to 100-fold in volume ratio.
However, if the organic hollow microspheres are heated more than necessary and bursted,
they can no longer serve as an effective component of an explosive, so that it is
recommended to stop heating before reaching a temperature at which overfoaming may
be caused.
[0024] The explosive composition according to the present invention can be presented in
various forms such as solid, powder, flakes, paste, etc., and it can be packed with
a known packaging material such as paper, laminated paper, plastic film, laminated
plastic film, paper tube, plastic tube, etc., selected according to the form of the
composition, its properties, object of use and other factors, and thus can be commercially
offered in the form of packs.
[0025] The explosive composition of this invention is capable of well satisfying the quality
requirements for an explosive, but for additional improvement of blasting performance,
an organic nitrate such as a lower saturated aliphatic amine or an inorganic nitrate
such as hydrazine nitrate may be added as a sensitizer to accommodate use in the cold
districts. Also, in consideration of gas release after blasting in a tunnel or underground
mine, a solid inflammable material such as coal powder or aluminum powder may be additionally
supplied. Other pertinent substances, for example, an activator such as phosphoric
ester, a decomposition inhibitor such as urea, etc., may be safely added as desired.
[0026] With the explosive composition and its producing method according to the present
invention, there can be obtained a variety of explosives ranging from the booster-blasted
type to the percussion-initiated type, and the explosives with a wide variety of dead
pressing density. The present invention can be applied to formulation of almost all
sorts of conventional explosives. Also, the explosive composition of this invention
is improved in dead pressing phenomenon attendant on the emulsion explosives, that
is, improved in anti-dead pressing property, and the safety in the work field can
be further improved due to the reduction of the unexploded compound residue. The production
method according to this invention needs no high-degree production techniques such
as required in the production of the conventional slurry and emulsion explosives,
and is capable of producing a desired type of explosive with ease and safety.
[0027] The explosive composition of this invention can be usually detonated by using various
known systems such as electric detonator, industrial detonator, detonator with blasting
tube, detonator with gas-blasting tube, electromagnetic detonator, laser detonator,
wireless detonator, blasting fuse, detonating fuse, etc. In some cases, the explosive
composition may be detonated by using a booster.
EXAMPLES
[0028] The present invention will hereinafter be described in more detail with reference
to the examples thereof, which examples, however, are merely intended to be illustrative
and not to be construed as limiting the scope of the invention. The cap sensitivity,
booster performance, velocity of detonation, cartridge propagation in steel tube and
anti-dead pressing property in sand were determined by the following methods.
Determination of cap sensitivity
[0029] An explosive charge was densely packed in a polyethylene laminated paper tube or
a nylon 66 film tube (pack diameter: 20 mm or 30 mm; pack length: about 200 mm) and
kept in a refrigerator of about -30°C for about 15 hours. Thereafter, the charge,
with its temperature adjusted, was detonated by a #6 detonator, and the temperature
at which the charge was perfectly exploded was measured. For evaluating the keeping
quality, the same detonation test was conducted on the same explosive charge which
has been kept in storage for one year after production thereof.
Determination of booster performance
[0030] A test explosive filled in a steel cylinder (JIS G 3452 32A; inner diameter: 36 mm;
length: 350 mm) closed on one side in the longitudinal direction was detonated by
a booster (50 g of #2 Enoki dynamite attached with a #6 detonator), and from visual
observation of the state of wrecking of the steel cylinder, it was determined whether
perfect explosion occurred or not. For evaluating the keeping quality, the same detonation
test was conducted on the same explosive which has been kept in storage for one year
after production thereof.
Determination of velocity of detonation of packed explosive
[0031] An explosive charge packed in a polyethylene laminated paper tube or a nylon 66 film
tube (pack diameter: 20 mm or 30 mm; pack length: 300 mm) was detonated by a #6 detonator,
and the velocity of detonation was determined by the ion gap method. For evaluating
the keeping quality, the same detonation test was conducted on the same explosive
which has been kept in storage for one year after production thereof.
Determination of velocity of detonation of explosive packed steel tube
[0032] An explosive packed in a steel tube (JIS G 3452 32A; inner diameter: about 36 mm⌀;
length: 350 mm) was detonated by a booster (50 g of #2 Enoki dynamite attached with
a #6 detonator), and the velocity of detonation was determined by the ion gas method.
For evaluating the keeping quality the same detonation test was conducted on the same
explosive which has been kept in storage for one year after production thereof.
Propagation test by cartridge in steel tube
[0033] An explosive charge was packed in a polyethylene laminated paper tube or a nylon
66 film tube (pack diameter: about 20 mm⌀; pack length: 150 mm), and about 20 packs
were set in juxtaposition to each other in a steel tube (JIS G 3452 40A; inner diameter:
about 41.6 mm; length: 3,000 mm) so that no deformation would take place in the longitudinal
direction. Then the pack at an end was detonated by #6 detonator and the length of
the wrecked portion of the steel tube was measured to determine propagation performance
in steel tube. For evaluating the keeping quality, the same test was conducted on
the same packs which have been kept in storage for one year after production thereof.
Determination of anti-dead pressing in sand
[0034] An explosive charge was packed in a polyethylene laminated paper tube or a nylon
66 film tube (pack diameter: 30 mm; pack length: about 150 mm). There were prepared
2 packs, and they were arranged side by side and buried 80 cm deep in sand, with an
instantaneous #6 electric detonator attached to one pack while a 10 ms short-delay
electric detonator attached to the other pack. Both electric detonators were connected
in series and electrified for detonating the explosive. This test was conducted 5
times repeatedly, and it was checked whether the explosive pack attached with the
10 ms short-delay electric detonator was perfectly detonated or not to determine anti-dead
pressing property in sand. For evaluating the keeping quality, the same test was conducted
on the same packs which have been kept in storage for one year after production thereof.
Example 1
[0035] 805 g of ammonium nitrate and 135 g of water were mixed and heated to about 90°C.
Meanwhile, 60 g of organic hollow microspheres (EXPANCEL® 551DE (a vinylidene chloride-acrylonitrile-methacrylic
ester copolymer) produced by Expancel AB) was weighed out and put into a polyethylene
bag. Then the above mixture was charged into the polyethylene bag. Thereafter, the
opening of the bag was closed and the materials in the bag were mixed with stirring
for about 10 minutes by applying a force to the bag sidewise thereof and then cooled
with water to obtain an explosive composition with an explosive density of 0.40 g/cm³.
This explosive composition was packed in a steel tube (JIS G 3452 32A; inner diameter:
about 36 mm; length: 350 mm) which had been closed on one side in the longitudinal
direction, and detonated by a booster (50 g of #2 Enoki dynamite attached with a #6
detonator). There took place perfect detonation. When the same test was conducted
with the same explosive composition kept in storage for one year after production
thereof, the similar results were obtained.
Example 2
[0036] 1608 g of ammonium nitrate, 310 g of water and 82 g of non-foamed organic microspheres
(MATSUMOTO MICROSPHERE F-30 which is a vinylidene chloride-acrylonitrile-methacrylic
ester copolymer produced by Matsumoto Yushi-Seiyaku Co., Ltd.) were supplied into
a metallic container and mixed with stirring in an external bath of about 80°C to
obtain a mixture of about 70°C. There was also prepared a metal plate heated to about
100-150°C. The above mixture was dropped peacemeal onto the surface of said metal
plate, whereby a granular explosive composition could be obtained in a very short
time.
[0037] This explosive composition was dispensed and packed in the polyethylene laminated
paper tubes of 20 mm and 30 mm in diameter to obtain the explosive packs each containing
30-40 g of said composition, and their blasting performance was examined. The density
of the 30 mm-diameter pack was 0.35 g/cm³, and this pack could be detonated by a #6
detonator at -10°C. The rate of detonation at the temperature of 5°C was 1,900 m/s.
The 2 mm-diameter pack was loaded in a steel tube having an inner diameter of 41.6
mm and a length of 3 m and detonated from one end thereof by a #6 detonator. As a
result, all of the explosive charge was perfectly detonated, and the length of the
wrecked portion of the steel tube was 3 m. Further, two pieces of said 30 mm-diameter
explosive pack were subjected to an in-sand dead pressing test in which the two packs
were buried in sand parallel to each other with a spacing of 15 cm therebetween, with
an instantaneous #6 detonator attached to one pack and a 10 ms short-delay electric
detonator attached to the other pack, and detonated by electrifying said detonators.
This test was conducted 5 times, and both packs were perfectly detonated in each run
of test. When the same test was conducted using the same packs which have been kept
in storage for one year after production thereof, the similar result was obtained.
On the other hand, when the same test was carried out using the conventional slurry
and emulsion explosives prepared by an ordinary method, with the charge density properly
adjusted, any of the packs could not be detonated by a #6 detonator a temperature
below 0°C. Also, in an explosive charge propagation test in a steel tube, detonation
was interrupted at a point close to 1.2 m from the detonated end, and the length of
the wrecked portion of the steel tube was about 0.8-1.6 m. Further, in an in-sand
dead pressing test, two of the explosive packs attached with a 10 ms short-delay electric
detonator were not perfectly detonated and recovered as incompletely exploded packs.
When the same test was conducted with the same packs kept in storage for one year
after production thereof, it was found that any of them was deteriorated in performance
quality to an extent that they could not be detonated by a #6 detonator.
Examples 3-5
[0038] The following explosive compositions were produced in the same way as Example 1,
and their blasting performance was examined.
|
Example 3 |
Example 4 |
Example 5 |
Ammonium nitrate |
1530 g |
1550 g |
1530 g |
Water |
270 g |
270 g |
270 g |
Non-foamed organic microspheres 1 |
200 g |
- |
- |
Non-foamed organic microspheres 2 |
- |
180 g |
- |
Non-foamed organic microspheres 3 |
- |
- |
200 g |
[0039] The non-foamed organic microspheres 1 were the same as used in Example 2. The non-foamed
organic microspheres 2 were made of an acrylonitrile-methyl methacrylate copolymer
(053WU produced by Expancel AB), and the non-foamed organic microspheres 3 were composed
of an acrylonitrile-acrylic ester copolymer (MATSUMOTO MICROSPHERE F-30, Matsumoto
Yusi-Seiyaku Co., Ltd.).
[0040] The 20 mm-diameter and 30 mm-diameter pack densities of the above three explosive
compositions were 0.23, 0.30 and 0.40, respectively. The 30 mm-diameter packs at a
temperature of -10°C could be detonated by a #6 detonator. The velocity of detonation
of said three explosive compositions at a temperature of 5°C was 1,900 m/s, 2,000
m/s and 2,200 m/s, respectively. When a 20 mm-diameter pack was loaded in a steel
tube of 41.6 mm in inner diameter and 3 m in length and detonated from one end thereof,
all of the explosive charge was perfectly detonated and the length of the wrecked
portion of the steel tube was 3 m. When the same test was conducted using the same
explosive compositions left one year after production thereof, the similar results
were obtained. On the other hand, when the same test was conducted using the conventional
slurry and emulsion explosives prepared by an ordinary process, with the explosive
charge density being properly adjusted, any of the explosive packs could not be detonated
at a temperature below 0°C. Also, in an explosive pack propagation test in a steel
tube, detonation was interrupted at a point close to 0.8-1.6 m from the detonated
end, and the length of the wrecked portion of the steel tube was about 0.8-1.6 m.
The same test was further carried out using the same explosive compositions kept in
storage for one year after production thereof, but any of the compositions has been
deteriorated in performance quality to the extent that it could not be detonated by
a #6 detonator.
Example 6
[0041] 1608 g of ammonium nitrate, 310 g of water and 82 g of non-foamed organic microspheres
(MATSUMOTO MICROSPHERE F-30 which is a vinylidene chloride-acrylonitrile-methacrylic
ester copolymer, produced by Matsumoto Yusi-Seiyaku Co., Ltd.) were charged into a
metallic container and mixed with stirring in a water bath of about 70°C to obtain
a mixture of about 70°C. This mixture was injected into a 20 mm-diameter metallic
tube (Teflon coated on the inner wall), which had been heated to about 100-150°C,
from one end thereof, and an open-cell foamed string-shaped explosive composition
was obtained from the other end.
[0042] The thus obtained explosive composition was dispended to form the explosive packs
in the manner described above, and their blasting performance was examined. The density
of the 20 mm⌀ packs was 0.45 g/cm³, and these packs could be detonated by a #6 detonator
at a temperature of -5°C. The velocity of detonation at the temperature of 5°C was
1,900 m/s. When an explosive pack, cut to a length of 3 m, was loaded in a steel tube
of 41.6 mm in diameter and 3 m in length and detonated from one end thereof by a #6
detonator, all of the explosive charge was perfectly detonated and the length of the
wrecked portion of the steel tube was 3 m. Further, two pieces of said 30 mm⌀ explosive
pack were subjected to an in-sand dead pressing test in which the two packs were buried
80 cm deep in sand parallel to each other with a spacing of 15 cm therebetween, with
an instantaneous #6 detonator attached to one of said packs and a 10 ms short-delay
electric detonator attached to the other pack, and both detonators were electrified
simultaneously to cause detonation. This test was conducted 5 times. Both packs were
perfectly detonated in each run of test. When the same test was carried out using
the same explosive composition which had been kept in storage for one year after production
thereof, the similar result was obtained.
Example 7
[0043] 1,524 g of ammonium nitrate, 286 g of water and 190 g of non-foamed organic microspheres
(MATSUMOTO MICROSPHERE F-30, a vinylidene chloride-acrylonitrile-methacrylic ester
copolymer produced by Matsumoto Yusi-Seiyaku Co., Ltd.) were put into a metallic container
and mixed with stirring in an external bath of about 90°C to obtain a mixture of about
70-80°C. This mixture was injected into a 20 mm⌀ metal tube (Teflon coated on inner
wall), which had been heated to about 90-110°C, from the opening at one end thereof,
and a creamy explosive composition having a density of 1.35 g/cm³ was obtained from
the opening at the other end.
[0044] When the above explosive composition was packed in a steel tube (JIS G 3452 32A;
inner diameter: 36 mm; length: 350 mm), which had been closed on one side in the longitudinal
direction, and detonated by a booster (50 g of #2 Enoki dynamite attached with a #6
detonator), said composition was perfectly detonated, and the velocity of detonation
was 5,460 m/s. When the same test was conducted using the same explosive composition
kept in storage for one year after production thereof, the similar result was obtained.
Examples 8-10
[0045] The following explosive compositions were produced by following the procedure of
Example 7, and their blasting performance was examined.
|
Example 8 |
Example 9 |
Example 10 |
Ammonium nitrate |
1560 g |
1524 g |
1530 g |
Water |
320 g |
286 g |
270 g |
Non-foamed organic microspheres 1 |
120 g |
- |
- |
Non-foamed organic microspheres 2 |
- |
190 g |
- |
Non-foamed organic microspheres 3 |
- |
- |
200 g |
[0046] The non-foamed organic microspheres 1 were the same as used in Example 1, and the
non-foamed organic microspheres 2 were made of an acrylonitrile-methyl methacrylate
copolymer (053WU, Expancel AB). The non-foamed organic microspheres 3 were composed
of an acrylonitrile-acrylic ester copolymer (MATSUMOTO MICROSPHERE F-50, Matsumoto
Yusi-Seiyaku Co., Ltd.).
[0047] The densities of the above three explosive compositions were 1.38 g/cm³ and 1.35
g/cm³, respectively. Each of the above explosive compositions was packed in a steel
tube (JIS G 3452 32A; inner diameter: about 36 mm; length: 350 mm), which had been
closed on one side in the longitudinal direction, and detonated by a booster (50 g
of #2 Enoki dynamite attached with a #6 detonator). As a result, each of said explosive
compositions was detonated perfectly, and the velocity of detonation was 5,500 m/s,
4,600 m/s and 5,100 m/s, respectively. When the same test was conducted on the same
explosive compositions which had been kept in storage for one year after production
thereof, the similar result was obtained.
Example 11
[0048] 1608 g of ammonium nitrate, 310 g of water and 82 g of non-foamed organic microspheres
(MATSUMOTO MICROSPHERE F-30, a vinylidene-acrylonitrile-methacrylic ester copolymer,
produced by Matsumoto Yusi-Seiyaku Co., Ltd.) were placed in a stainless steel container
and heated with slow stirring in an oil bath of about 100-130°C to obtain a creamy
explosive composition. This explosive composition was dispensed and packed in the
20 mm⌀ and 30 mm⌀ polyethylene laminated paper tubes to form the explosive packs each
containing about 50 g of said composition, and their blasting performance was examined.
The density of the 30 mm⌀ explosive pack was 0.70 g/cm³, and this pack could be detonated
by a #6 detonator at -5°C. The velocity of detonation at of 5°C was 2,500 m/s. The
20 mm⌀ pack was loaded in a steel tube of 41.6 mm in inner diameter and 3 m in length
and detonated from one end by a #6 detonator. All of the explosive charge was perfectly
detonated, and the length of the wrecked portion of the steel tube was 3 m. Further,
two 30 mm⌀ explosive packs were subjected to an in-sand dead pressing test in which
said two packs were buried 80 cm deep in sand parallel to each other with a spacing
of 15 cm therebetween, with a #6 electric detonator attached to one pack and a 10
ms short-delay detonator attached to the other pack, and detonated by electrifying
said detonators. This test was conducted 5 times. Both packs were perfectly detonated
in each run of test. When the same test was conducted on the same explosive composition
kept in storage for one year after production thereof, the similar result was obtained.
Example 12
[0049] 1,250 g of ammonium nitrate, 170 g of water and 160 g of sodium nitrate, 300 g of
monomethylamine nitrate and 120 g of non-foamed organic microspheres (MATSUMOTO MICROSPHERE
F-30, a vinylidene chloride-acrylonitrile-methacrylic acid copolymer) were mixed while
heating to about 70°C to form a homogeneous mixed solution. An amount of this solution,
determined by taking into consideration possible volume expansion on heating, was
filled in a 20 mm⌀ nylon 66 film tube. After deairing this tube and then closing both
ends thereof, said tube was placed in a hot bath of 100-150°C to heat the mixed solution
therein, causing foaming of the organic microspheres contained in said mixture, and
the blasting performance as an explosive composition packed in said nylon 66 film
tube was examined. The density of the explosive charge in said 20 mm⌀ nylon 66 film
tube was 0.35 g/cm³, and this explosive pack could be detonated by a #6 detonator
at -10°C. The velocity of detonation at 5°C was 2,200 m/s. Also, the above explosive
pack was loaded in a steel tube of 41.6 mm in diameter and 3 m long and detonated
from one end thereof by a #6 detonator. As a result, all of the explosive charge was
perfectly detonated, and the length of the wrecked portion of the steel tube was 3
m. When the same test was conducted using the same explosive composition which had
been kept in storage for one year after production thereof, the similar result was
obtained.
Example 13
[0050] 1,050 g of ammonium nitrate, 170 g of water, 300 g of sodium nitrate and 360 g of
monomethylamine nitrate were mixed and heated to about 70°C to prepare a mixture.
Meanwhile, 120 g of organic hollow microspheres (EXPANCEL® 551DE, a vinylidene chloride-acrylonitrile-methacrylic
ester copolymer produced by Expancel AB) was weighed out and placed in a polyethylene
bag. Then the above mixture was charged into said bag, and after closing its opening,
the bag was subjected to a stirring force applied to the bag sidewise thereof for
about 10 minutes to mix the materials in the bag, followed by cooling to obtain an
explosive composition. This explosive composition was dispensed and packed in the
20 mm⌀ and 30 mm⌀ polyethylene laminated paper tubes to form the explosive packs each
containing about 30-40 g of said composition, and their blasting performance was examined.
The density of the 30 mm⌀ explosive pack was 0.35 g/cm³, and this pack could be detonated
by a #6 detonator at of -20°C. The velocity of detonation at 5°C was 2,300 m/s. The
20 mm⌀ explosive pack was loaded in a steel tube of 41.6 mm in diameter and 3 m in
length and detonated from one end thereof by a #6 detonator. As a result, all of the
explosive charge was perfectly detonated, and the length of the wrecked portion of
the steel tube was 3 m. Further, a pair of 30 mm⌀ explosive packs were subjected to
an in-sand dead pressing test in which both packs were buried 80 cm deep in sand parallel
to each other with a spacing of 15 cm therebetween, with an instantaneous #6 detonator
attached to one pack and a 10 ms short-delay electric detonator attached to the other
pack, and detonated simultaneously by electrifying said detonators. This test was
conducted 5 times, and both packs were perfectly detonated in each run of test. When
the same test was carried out using the same explosive composition which had been
kept in storage for one year after production thereof, the similar result was obtained.
Examples 14 and 15
[0051] The following explosive compositions were produced by following the procedure of
Example 13, and their blasting performance was examined.
|
Example 14 |
Example 15 |
Ammonium nitrate |
1,520 g |
1,330 g |
Water |
80 g |
170 g |
Monomethylamine nitrate |
350 g |
300 g |
Sodium nitrate |
- |
160 g |
Organic hollow microspheres |
50 g |
40 g |
[0052] The 30 mm⌀ pack densities of the above two explosive compositions were 1.02 and 0.95,
respectively, and the packed compositions could be detonated by a #6 detonator at
0°C. The velocity of detonation at 5°C was 3,700 m/s and 3,200 m/s, respectively.
When the same test was conducted on the same explosive compositions which had been
kept in storage for one year after production thereof, the similar results were obtained.
Example 16
[0053] 1,296 g of ammonium nitrate, 164 g of water, 358 g of monomethylamine nitrate and
78 g of non-foamed organic microspheres (MATSUMOTO MICROSPHERE F-30 which is a vinylidene
chloride-acrylonitrile-methacrylic ester copolymer produced by Matsumoto Yusi-Seiyaku
Co., Ltd.) were placed in a metallic container and mixed by stirring the container
in a water bath of about 70°C to obtain a mixture of about 70°C. Meanwhile, there
was prepared a metal plate (Teflon coated on inner side) heated to about 100-150°C.
The above mixture was dropped peacemeal onto the surface of said hot metal plate,
thereby obtaining a granular explosive composition in a very short time.
[0054] This explosive composition was dispended and packed in the 20 mm⌀ and 30 mm⌀ polyethylene
laminated paper tubes to form the explosive packs each containing about 30-40 g of
said composition, and their blasting performance was examined. The density of the
30 mm⌀ explosive pack was 0.80 g/cm³, and this pack could be detonated by a #6 detonator
at -15°C. The velocity of detonation at 5°C was 3,700 m/s. The 20 mm⌀ explosive pack
was loaded in a steel tube of 41.6 mm in inner diameter and 3 m in length and detonated
from one end thereof by a #6 detonator. As a result, all of the explosive charge was
perfectly detonated, and the length of the wrecked portion of the steel tube was 3
m. Further, a pair of 30 mm⌀ explosive packs were subjected to an in-sand dead pressing
test in which both packs were buried 80 cm deep in sand parallel to each other with
a spacing of 15 cm therebetween, with an instantaneous #6 detonator attached to one
pack and a 10 ms short-delay electric detonator attached to the other pack, and detonated
simultaneously by electrifying said detonators. This test was repeated 5 times, and
both packs were perfectly detonated in each run of test. When the same test was conducted
on the same explosive compositions which had been kept in storage for one year after
production thereof, the similar results were obtained.
Examples 17-19
[0055] The following explosive compositions were produced according to the process of Example
16 and their blasting performance was examined.
|
Example 17 |
Example 18 |
Example 19 |
Ammonium nitrate |
1338 g |
1490 g |
1470 g |
Water |
210 g |
170 g |
170 g |
Monomethylamine nitrate |
300 g |
240 g |
240 g |
Sodium nitrate |
- |
140 g |
- |
Non-foamed organic microspheres 1 |
152 g |
- |
- |
Non-foamed organic microspheres 2 |
- |
100 g |
- |
Non-foamed organic microspheres 3 |
- |
- |
120 g |
[0056] The non-foamed organic microspheres 1 are the same as used in Example 16, and the
non-foamed organic microspheres 2 are made of an acrylonitrile-methyl methacrylate
copolymer (053WU, Expancel AB). The non-foamed organic microspheres 3 are composed
of an acrylonitrile-acrylic ester copolymer (MATSUMOTO MICROSPHERE F-50, Matsumoto
Yusi-Seiyaku Co., Ltd.).
[0057] The 20 mm⌀ and 30 mm⌀ pack densities of the above three explosive compositions were
0.20, 0.30 and 0.45, respectively. The 30 mm⌀ pack at -25°C could be detonated by
a #6 detonator. The velocity of detonation at 5°C was 1,900 m/s, 2,300 m/s and 2,500
m/s, respectively. The 20 mm⌀ pack was loaded in a steel tube of 41.6 mm in diameter
and 3 m in length and detonated from one side by a #6 detonator. The whole pack charged
was detonated perfectly, and the length of the wrecked portion of the steel tube was
3 m. When the same test was carried out on the same explosive compositions which had
been kept in storage for one year after production thereof, the similar results were
obtained.
Example 20
[0058] 1,346 g of ammonium nitrate, 240 g of water, 80 g of sodium nitrate, 174 g of monomethylamine
nitrate and 160 g of non-foamed organic microspheres (MATSUMOTO MICROSPHERE F-30)
were supplied into a stainless steel container and heated with slow stirring in an
oil bath of about 80-90°C to obtain an explosive composition with an explosive density
of 1.38 g/cm³. When this explosive composition was charged into a steel tube (JIS
G 3452 32A; inner diameter: 36 mm; length: 350 mm), which had been closed on one side
in the longitudinal direction, and detonated by a booster (50 g of #2 Enoki dynamite
attached with a #6 detonator), the above explosive composition was perfectly detonated.
The velocity of detonation was 5,600 m/s. When the same test was conducted on the
same explosive composition which had been kept in storage for one year after production
thereof, the similar result was obtained.
INDUSTRIAL APPLICABILITY
[0059] The explosive composition according to the present invention, in virtue of its peculiar
structure in which the active component comprising an oxidizer and water or a sensitizer,
an oxidizer and water is held continuously on the surfaces of and/or in the spaces
between the adjoining microspheres, substantially unnecessitates use of a thickener
which has been indispensable for maintenance of quality of the conventional hydrous
explosive compositions, and it can not only keep its quality for a long time but also
realized practical use of the low-specific-gravity products which has been considered
unfeasible with the conventional hydrous explosives. Owing to reduction of specific
gravity, the noise and vibration generated at the time of blasting can be remarkably
lessened.
1. An explosive composition comprising an oxidizer, water and organic hollow microspheres,
wherein a phase substantially composed of said oxidizer and water is adsorbed and
held on the surfaces of and/or between said organic hollow microspheres.
2. An explosive composition according to Claim 1, wherein the organic hollow microspheres
are substantially spherical.
3. An explosive composition according to Claim 1 or 2, wherein the organic hollow microspheres
are thermoplastic.
4. An explosive composition according to any of Claims 1-3, wherein the thermoplastic
organic hollow microspheres are made of a vinylidene chloride-acrylonitrile copolymer.
5. An explosive composition according to any of Claims 1-3, wherein the thermoplastic
organic hollow microspheres are made of a vinylidene chloride-acrylonitrile-methacrylic
ester copolymer.
6. An explosive composition according to any of Claims 1-3, wherein the thermoplastic
organic hollow microspheres are made of an acrylonitrile-acrylic ester copolymer.
7. An explosive composition pack in which an explosive composition according to any of
Claims 1-6 is packed in a packaging material.
8. A method of producing an explosive composition substantially consisting of an oxidizer,
water and organic hollow microspheres, said organic hollow microspheres being used
as an inflammable component, which method comprises mixing 2-15% by weight of foamable
organic microspheres, 3-20% by weight of water and the balance essentially consisting
of an oxidizer to prepare a composition substantially free of aerated bubbles, and
then heating and foaming said composition.
9. The method according to Claim 8, wherein the foamable organic microspheres are substantially
spherical.
10. The method according to Claim 8 or 9, wherein the foamable organic microspheres are
thermoplastic.
11. The method according to any of Claims 8-10, wherein the thermoplastic foamable organic
microspheres are made of a vinylidene chloride-acrylonitrile copolymer.
12. The method according to any of Claims 8-10, wherein the thermoplastic foamable organic
microspheres are made of a vinylidene chloride-acrylonitrile-methacrylic ester copolymer.
13. The method according to any of Claims 8-10, wherein the thermoplastic foamable organic
microspheres are made of an acrylonitrile-acrylic ester copolymer.
14. An explosive composition pack in which an explosive composition according to any of
Claims 8-13 is packed in a packaging material.
15. An explosive composition comprising an oxidizer, water and organic hollow microspheres,
wherein a phase substantially composed of a sensitizer, an oxidizer and water is adsorbed
and held on the surfaces of and/or between said organic hollow microspheres.
16. An explosive composition according to Claim 15, wherein the organic hollow microspheres
are substantially spherical.
17. An explosive composition according to Claim 15 or 16, wherein the organic hollow microspheres
are thermoplastic.
18. An explosive composition according to any of Claims 15-17, wherein the thermoplastic
organic hollow microspheres are made of a vinylidene chloride-acrylonitrile copolymer.
19. An explosive composition according to any of Claims 15-17, wherein the thermoplastic
organic hollow microspheres are made of a vinylidene chloride-acrylonitrile-methacrylic
ester copolymer.
20. An explosive composition according to any of Claims 15-17, wherein the thermoplastic
organic hollow microspheres are made of an acrylonitrile-acrylic ester copolymer.
21. An explosive composition pack in which an explosive composition according to any of
Claims 15-20 is packed in a packaging material.
22. A method of producing an explosive composition substantially consisting of a sensitizer,
an oxidizer, water and organic hollow microspheres, which comprises mixing 2-15% by
weight of foamable organic microspheres, 3-20% by weight of water and the balance
essentially consisting of a sensitizer and an oxidizer to prepare a composition substantially
free of aerated bubbles, and heating and foaming said composition.
23. The method according to Claim 22, wherein the foamable organic microspheres are substantially
spherical.
24. The method according to Claim 22 or 23, wherein the foamable organic microspheres
are thermoplastic.
25. The method according to any of Claims 22-24, wherein the thermoplastic organic microspheres
are made of a vinylidene chloride-acrylonitrile copolymer.
26. The method according to any of Claims 22-24, wherein the thermoplastic foamable organic
microspheres are made of a vinylidene chloride-acrylonitrile-methacrylic ester copolymer.
27. The method according to any of Claims 22-24, wherein the thermoplastic foamable organic
microspheres are made of an acrylonitrile-acrylic ester copolymer.
28. An explosive composition pack in which an explosive composition produced according
to any of the methods of Claims 22-27 is packed in a packaging material.