JP2000233988A - Granular explosive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance water resistance of the composition and to maintain and improve its performance by coating (or mixing) ammonium nitrate used as the main component of a granular explosive composition, with a coating agent. SOLUTION: In the preparation of this composition: (1) ammonium nitrate, i.e., a main component of the composition, is coated with a coating agent; (2) a powdery metal is added to and mixed into the coated ammonium nitrate described in the item (1); (3) the coating agent described in the item (1) is a mixture of at least three materials selected from three groups of materials respectively, wherein the three groups are a group of waxes, a group of polymers such as polystyrene, polyvinyl acetate, ethyl cellulose and nitrocellulose, and a group of aromatic dinitro compounds; (4) the powdery metal described in the item (2) is at least one powdery metal selected from powdery aluminum, magnesium, magnalium and ferrosilicon; (5) in the item (1) or (2), a water-insoluble void-filler material is added to the interparticle spaces of ammonium nitrate particles and mixed into them; (6) the void-filler material described in the item (5) consists of gelatinized granules; and (7) the gelatinized granules described in the item (6) are obtained by granulating a gelatinized material formed from water or an oxidizing agent aqueous solution and a water-soluble thickening agent such as guar gum or locust-bean gum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the mining of mineral resources,
It relates to industrial explosives used for civil engineering construction work and the like.

[0002]

2. Description of the Related Art Generally, industrial explosives contain ammonium nitrate as a main component and water of at least 5% by weight in order to enhance safety, in addition to explosives which have been well known, such as dynamite and carlit. There are two types of explosives: water-containing explosives and extremely low-cost ANFO explosives.

[0003] Among these explosives, the ANFO explosive is a granular explosive composed of 94% of porous prilled ammonium nitrate and 6% of light oil. Since this ANFO explosive cannot be detonated with a single No. 6 detonator, it is insensitive and safer than other general explosives (usually booster detonation). Moreover, since it is a fluid granular material, it can be poured directly into the blasting borehole.

[0004] Furthermore, the simplest explosive, a combination of ammonium nitrate (ammonium nitrate) and light oil, is inexpensive compared to other general explosives, and is therefore the most widely consumed industrial explosive. It is well known that no explosives are found beyond explosives.

[0005]

However, the ANFO explosive containing ammonium nitrate as a main component is a mixture of ammonium nitrate and light oil, but has a problem that it has no water resistance.

[0006] The actual borehole at the blasting site generally has water in many cases and is in a muddy state, so that the specific gravity of the water is 1.10 or more. Therefore, under certain conditions, i.e., when water is present in the blast borehole, underground water seeps, or when water penetrates into the borehole in rainy weather, the component ammonium nitrate is easily dissolved, Light oil is separated by dissolution of this ammonium nitrate, it loses explosiveness, and it may become non-explosive,
Under these conditions, the use of ANFO explosives becomes difficult.

Therefore, high explosives such as water-resistant trinitrotoluene (TNT) and trimethylenetrinitroamine (RDX) which can be used under such conditions are used. Since these high explosives do not dissolve in water and have a specific gravity much higher than that of water (about 1.7), they can be poured directly into boreholes, deposit in water holes, and maintain explosive performance. But the explosive unit price increases.

There is also a method in which an ANFO explosive is used by filling it with a water-resistant plastic cartridge. However, the bulk specific gravity of the ANFO explosive is about 0.85, and the bulk specific gravity of the entire cartridge is smaller than that of water. Therefore, in order to submerge in the water hole, it is necessary to weight the cartridge. The charging operation becomes extremely complicated.

The above-mentioned dynamite and water-containing explosives are water-resistant, but their explosive unit prices are higher than ANFO explosives. In addition, these explosives that are commercially available are cartridge-type explosives individually mounted in a cartridge, and have a drawback that they cannot be directly poured into a borehole because they are not granular,
This will increase the blasting cost. In addition, various studies have been conducted to impart water resistance to the ANFO explosive, and one of them is a mixture of the ANFO explosive and a special dry component such as guar gum.

[0010] When water infiltrates the ANFO explosive after loading, guar gum absorbs the water, swells, and forms a peripheral wall in the form of a paste. This uses a method to prevent water from entering the explosive.

However, in this method, when the guar gum comes in contact with water, it immediately absorbs the water, swells, and forms mushy walls on the water surface. For this reason, it is difficult to load the ANFO explosive continuously, and in such a muddy, watery state, the explosive weight occupying the borehole becomes extremely small, and the explosive performance may be lost.

For this reason, it is not possible to directly load the water into the water hole, and it is necessary to remove water from the bore hole in advance and then load the water. Therefore, the present inventors have focused on ammonium nitrate, which is difficult to dissolve in water pores and gives high water resistance, and as a result of intensive research, by coating ammonium nitrate with a specific coating agent, even if water is present, The present inventors have found an unprecedented granular explosive capable of maintaining explosive performance and having high water resistance, and have completed the present invention.

The current granular explosive has a water content of 2%.
If it is 5 vol% or less, it detonates, but if it exceeds 25 vol%, the detonation may be interrupted or a non-explosion may occur. on the other hand,
The space between the explosive particles of the granular explosive is about 30 vol% or more, and when filling the water hole, the space is replaced by water, and at least 30 vol% of water is present, and the explosive property is lost.

Therefore, by filling the gaps between the particles of the granular explosive composition coated with the coating agent with the granulated void filling material, it is possible to maintain the explosive performance against water holes and adjust the oxygen balance. I found it. That is,
An object of the present invention is to provide a granular explosive composition which is inexpensive, has excellent fluidity, and is hardly soluble in water.

[0015] Another object of the present invention is to further improve the explosive performance by adding and mixing a water-insoluble void-filling material, for example, an elastic gelled granule, to the voids between the particles of the granular explosive composition. An object of the present invention is to provide a granular explosive composition capable of maintaining and improving the explosive.

[0016]

The invention according to claim 1 is
It is characterized in that ammonium nitrate is coated with a coating agent. The invention according to claim 2 is characterized in that the granular explosive composition according to claim 1 is obtained by adding and mixing a metal powder.

According to a third aspect of the present invention, in the granular explosive composition according to the first aspect, the coating agent comprises a wax,
It is a mixture of at least three kinds of polymers selected from the group consisting of polymers such as polystyrene, polyvinyl acetate, ethylcellulose, and nitrocellulose, and aromatic dinitro compounds such as dinitrobenzene and dinitrotoluene.

According to a fourth aspect of the present invention, in the granular explosive composition of the second aspect, the metal powder is at least one selected from the group consisting of aluminum, magnesium, magnalium and ferrosilicon. I do. The invention according to claim 5 is characterized in that, in the granular explosive composition according to claim 1 or 2, a water-insoluble gap filling material is added and mixed between the ammonium nitrate particles.

According to a sixth aspect of the present invention, there is provided the granular explosive composition according to the fifth aspect, wherein the void filling material comprises a gelled granule. The invention according to claim 7 is the granular explosive composition according to claim 6, wherein the gelled granules are water or water containing a dissolved oxidizing agent,
It is characterized in that it is a gelled granule granulated with a gelled product with a water-soluble thickener such as guar gum and locust bean gum.

The invention according to claim 8 is the granular explosive composition according to claim 7, wherein the oxidizing agent is ammonium nitrate, alkali metal nitrate, alkaline earth metal nitrate, alkali metal perchlorate, alkaline earth metal. It is at least one selected from the group consisting of metal-like perchlorates.

[0021]

DETAILED DESCRIPTION OF THE INVENTION The main ingredient used in the granular explosive composition of the present invention is ammonium nitrate, which is the cheapest and widely used. As the ammonium nitrate, granular or porous prilled ammonium nitrate may be used alone or in a mixture depending on the shape. Porous prilled ammonium nitrate is the most preferable because it has voids inside, so that it comes into close contact with the fuel component and has higher detonation sensitivity than other ammonium nitrates. The particle size is not particularly limited, and it is preferable to use porous prilled ammonium nitrate having a particle size of 2 mm or less in order to improve the charge density and explosiveness.

In the present invention, ammonium nitrate, which is the main component in the granular explosive composition, is used in the range of 50 to 98% by weight, and more preferably in the range of 70 to 95% by weight. The coating used in the granular explosive composition of the present invention is a mixture mainly composed of three kinds of organic substances.

One of those waxes is a solid wax at normal temperature, and is used alone or as a mixture of petroleum waxes such as paraffin wax and microcrystalline wax, animal and plant waxes, mineral waxes and synthetic waxes. . In particular, in the present invention, in order to further enhance and improve properties such as water resistance and toughness of the coating agent, a wax containing ethylene vinyl acetate, synthetic rubber, modified rosin, etc. (for example, a product of Nippon Seirowa Co., Ltd. A certain POLY
COAT series products and PALVAX series products) are used.

The composition is used in the range of 0 to 15% by weight, and more preferably in the range of 5 to 10% by weight. Another type is polystyrene, polyvinyl acetate,
Polymers such as ethyl cellulose and nitrocellulose,
Used alone or in a mixture. When using nitrocellulose, a weak cotton having a nitrification degree of 12.5% or less is preferable. The compounding ratio is in the range of 0 to 10% by weight, and more preferably in the range of 2 to 5% by weight.

As another type, aromatic dinitro compounds such as dinitrobenzene and dinitrotoluene are used. The composition is used in the range of 0 to 25% by weight, and more preferably in the range of 5 to 20% by weight. Next, a method for producing the granular explosive of the present invention will be described. First, a soluble polymer (polystyrene, polyvinyl acetate, ethylcellulose, nitrocellulose, etc.) is dissolved in an organic solvent (acetone, methanol, ethanol, etc.), and granular or porous prilled ammonium nitrate is uniformly dispersed and mixed therein. . Thereafter, the wax which has been heated to 90 ° C. and is in a liquid state is mixed with dinitrotoluene, and the above mixture is added to this mixture and mixed. After the organic solvent evaporates under stirring, a film of a mixture of polymer, wax and dinitrotoluene is formed on the surface of ammonium nitrate. Thereafter, the mixture is cooled to room temperature with stirring to obtain a granular explosive composition.

The granular explosive composition has excellent fluidity and is hardly soluble in water. In order to improve the power of the granular explosive of the present invention, a metal powder is added to the granular explosive composition. Aluminum, magnesium, magnalium and ferrosilicon are used as the metal powder.

Of these, aluminum is preferred. Depending on the shape, this aluminum includes flake-like aluminum and atomized aluminum, and it is possible to use these shapes of aluminum alone or as a mixture. By adding this metal powder, a granular explosive with excellent explosive power can be obtained.

In addition, the granular explosive composition of the present invention contains 50% by weight or less of gelled granules having a particle size of 1.4 mm or less as a material for adjusting the oxygen balance and filling voids between particles of the granular explosive. Mix. The gelled granules are composed of 89.5 to 94.5% by weight of an oxidizing agent aqueous solution having a concentration of 0% to 80%, 5 to 10% by weight of a water-soluble thickener, and 0.2% of a crosslinking agent.
5 to 0.5% by weight.

As the oxidizing agent, ammonium nitrate, alkali metal nitrates, alkaline earth metal nitrates, alkali metal perchlorates, alkaline earth metal perchlorates are used alone or as a mixture. Most preferred is ammonium nitrate. As a water-soluble thickener,
Natural gums such as guar gum and locust bean gum are used.

As the crosslinking agent, potassium hydrogen pyroantimonate or sodium hydrogen pyroantimonate is used. By adding and mixing the gelled granules to the granular explosive composition, it is possible to further improve and maintain the explosive performance for water holes.

[0031]

The present invention will be specifically described below with reference to examples and comparative examples.

Example 1 Acetone 92 as an organic solvent
8% by weight of nitrocellulose having a nitrification degree of 12.5% (weak cotton manufactured by Daicel Chemical Co., Ltd.)
A weight percent nitrocellulose solution was obtained. Porous prilled ammonium nitrate (MK manufactured by Mitsubishi Chemical Corporation) 7
0% by weight was uniformly dispersed and mixed in 62.5% by weight of the above-mentioned nitrocellulose solution (nitrocellulose content was 5% by weight).

Thereafter, the wax was heated to about 90 ° C. and turned into a liquid state (PALVAX1335 manufactured by Nippon Seiro Co., Ltd.)
5% by weight and dinitrotoluene (Sumitomo Chemical Co., Ltd.) 2
0% by weight, and the mixture of ammonium nitrate was added to the mixture and mixed. After the acetone was evaporated under stirring, a film of a mixture of nitrocellulose, wax and dinitrotoluene was formed on the surface of the porous prilled ammonium nitrate.

Thereafter, the mixture was cooled to room temperature with further stirring to obtain a granular explosive composition (corresponding to claims 1 and 3). (Examples 2 to 4) 96% by weight of the granular explosive composition of Example 1
Flaked aluminum (Toyo Aluminum Co., Ltd. P
F0100S) was added and mixed to obtain a granular explosive composition of the present invention (corresponding to claims 1, 2, 3, and 4).

(Examples 5 to 7) To 98% by weight of the granular explosive composition of Example 1, 2% by weight of flake aluminum (PF0100S manufactured by Toyo Aluminum Co., Ltd.) was added and mixed.
The granular explosive composition of the present invention was obtained (Claims 1, 2, 3, and 4).
Corresponding to).

Examples 8 to 10 56.8% by weight of granular ammonium nitrate (MK manufactured by Mitsubishi Chemical Corporation) and water 3
A gel obtained by mixing 94.7% by weight of an aqueous solution of ammonium nitrate having a concentration of 7.9% by weight and having a concentration of 94.7% by weight, guar gum 5% by weight, and potassium hydrogen pyroantimonate 0.3% by weight has a mesh size of 1.4 mm. The mixture was granulated with a sieve to obtain gelled granules.

The gelled granules 30% by weight and flake aluminum (PF0100 manufactured by Toyo Aluminum Co., Ltd.)
S) 2% by weight, 68% by weight of the granular explosive composition of Example 1
To obtain a granular explosive composition of the present invention (corresponding to claims 1, 2, 3, 4, 5, 6, 7, and 8). (Comparative Examples 1-2) Wax (PALVA manufactured by Nippon Seiro Co., Ltd.) previously heated and dissolved in 94% by weight of porous prilled ammonium nitrate (MK product manufactured by Mitsubishi Chemical Corporation)
X1335) was added at 6% by weight and sufficiently stirred and mixed at 90 ° C. to obtain a granular explosive composition.

The compositions of Examples 1 to 10 and Comparative Examples 1 and 2 are summarized in Table 1.

[Table 1] Next, the ammonium nitrate dissolution rate of the granular explosive compositions of Example 1 and Comparative Example 1 was examined.

As a method for examining the dissolution rate of ammonium nitrate, a 100 g sample was charged into a measuring cylinder containing 400 cc of water, and the specific gravity of the aqueous solution corresponding to the elapsed time after the charging was measured using a floating meter. Using the specific gravity of the obtained aqueous solution, from the relationship between the solubility s of ammonium nitrate in water and the specific gravity ρ of the solution, s = 300ρ−30
The dissolution rate of ammonium nitrate was determined based on 1.2 (the specific gravity of tap water was 1.004).

FIG. 1 shows the ammonium nitrate dissolution rate of the granular explosive compositions of Example 1 and Comparative Example 1. In FIG. 1, in Example 1, the dissolution rate after 1 hour was 3.2%, and was about 19.2% even after 3 hours. On the other hand, Comparative Example 1 showed a dissolution rate exceeding 95% in about 30 minutes.

Next, Examples 2 to 10 and Comparative Examples 1 to 2
The presence of water for the granular explosive composition of
The explosion performance when not present was investigated. As a method of examining the explosion performance, an inner diameter of 36.5 mm and a length of 250 mm
Were charged with the granular explosive compositions of Examples 2, 5, and 8 and Comparative Example 1, respectively, and the explosion velocity was measured. About Examples 3-4, 6-7, 9-10, and Comparative Example 2, an inner diameter of 36.5 mm and a length of 250 mm
Was poured into an iron pipe (JIS-G-3452), and the iron pipe was filled with the granular explosive composition, and the explosion velocity was measured.

As a method of measuring the explosion velocity, a diameter of 30 m
m, an energite, an emulsion explosive manufactured by Nippon Koki Co., Ltd., with a dose of 100 g was used for detonation, and it was detonated from the top of the iron pipe, and the time required for the shock wave to pass between two points 15 cm and 5 cm from the bottom of the iron pipe was measured by the ion gap method. And asked for the explosion speed. Table 2 summarizes the explosive performance of the granular explosive compositions of Examples 2 to 10 and Comparative Examples 1 and 2.

[Table 2] In Table 2, Examples 2, 5 and 8 in the absence of water
Compared with Comparative Example 1, the granular explosive composition of the present invention
It is clear that the loading density is high and the explosion speed is high.
Comparing Examples 3-4, 6-7 and 9-10 with Comparative Example 2 in the presence of water, only waxes were coated by using a mixture of waxes, nitrocellulose and dinitrotoluene as a coating agent. It is evident that the water resistance is remarkably improved and the explosion performance is maintained as compared with the case where it is used as an agent.

When Examples 2 to 4 and Examples 5 to 7 are compared, it is clear that the explosion velocity increases and the explosion energy increases as the amount of the flake-like aluminum metal powder increases. Comparing Examples 2 to 7 with Examples 8 to 10, it is clear that the use of gelled granules containing an oxidizing agent such as ammonium nitrate further improves the water resistance and increases the packing density and explosion velocity. It is.

The packing density in this case is a density calculated from the weight of the charged granular explosive and the volume occupied by the explosive.

[0045]

According to the present invention, the following effects can be obtained.

(1) Ammonium nitrate, which is the main component of the explosive, does not easily dissolve in water (water holes), and it is possible to obtain high water resistance and maintain explosive performance. (2) By mixing a water-insoluble void-filling material (eg, gelled granules) of particles smaller than ammonium nitrate into the voids between the ammonium nitrate particles, water entering between the explosive particles in the water holes is suppressed; Explosive performance can be maintained and improved. (3) The oxygen balance can be adjusted in the zero direction by mixing the gelled granules.

[Brief description of the drawings]

FIG. 1 shows the ammonium nitrate dissolution rate of the granular explosive compositions of Example 1 and Comparative Example 1.

Claims (8)

[Claims] 1. A granular explosive composition comprising ammonium nitrate coated with a coating agent. 2. The granular explosive composition according to claim 1, wherein a metal powder is added and mixed. 3. The granular explosive composition according to claim 1, wherein the coating agent comprises a wax, a polymer such as polystyrene, polyvinyl acetate, ethylcellulose, nitrocellulose, and an aromatic dinitrogen such as dinitrobenzene and dinitrotoluene. A granular explosive composition comprising at least three kinds of mixtures selected from the group consisting of compounds. 4. The granular explosive composition according to claim 2, wherein the metal powder is at least one selected from the group consisting of aluminum, magnesium, magnalium, and ferrosilicon. 5. The granular explosive composition according to claim 1, wherein a water-insoluble void-filling substance is added and mixed between the ammonium nitrate particles. 6. The granular explosive composition according to claim 5, wherein the void-filling material comprises gelled granules. 7. The granular explosive composition according to claim 6, wherein the gelled granule is a gel of water or water containing a dissolved oxidizing agent and a water-soluble thickener such as guar gum or locust bean gum. A granular explosive composition, characterized in that it is a gelled granule granulated by: 8. The granular explosive composition according to claim 7, wherein said oxidizing agent is ammonium nitrate, alkali metal nitrate, alkaline earth metal nitrate, alkali metal perchlorate, alkaline earth metal perchlorate. A granular explosive composition characterized by being at least one selected from the group consisting of: