JP2001089285A - Granular explosive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an explosive which improves the water resistance of porous prill ammonium nitrate, etc., and retaining ignitability and stable detonatability. SOLUTION: A wax film of a melting point of >=60 deg.C is formed only on the surfaces of the prill ammonium nitrate, powdery explosive and granular explosive, and viscous agent powder is added thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to blasting, crushing, excavation and the like of industrial explosives.

[0002]

2. Description of the Related Art Dynamite, hydrous explosives, and nitrous acid explosives (hereinafter, abbreviated as ANFO) are most commonly used as industrial explosives. The most consumed explosive is ANFO. This is because ANFO has a simple composition of ammonium nitrate and light oil, can be easily manufactured with a simple device, has low impact sensitivity, is safe, and is inexpensive. Currently used ANFO is composed of 94 parts by weight of ammonium nitrate and light oil.
/ 6. This is the composition that has the greatest power in consideration of oxygen balance.

[0003]

SUMMARY OF THE INVENTION However, ANF
O does not have water resistance because of its high solubility in its main component, ammonium nitrate, in water. ANFO cannot be used in water holes as it is. If used, AN
There is a method of packing FO in a polyethylene bag and isolating it from water. Also, U.S. Pat. As described in 4637849, a thickener such as guar gum and a cross-linking agent are added, which react with water to form a swellable barrier, which further cross-links to form a strong insoluble film. There is a way. However, the reaction of this thickener is slow, and when water flows into the blast hole much, water penetrates into the explosive and dissolves ammonium nitrate, and stable detonation energy is not generated due to the presence of water. May cause a detonation interruption. In US Pat. No. 4,933,029, for example, a thickener comprising a mixture of guar gum and a crosslinking agent and a water-repellent substance such as a fatty acid, a salt thereof, or a wax are added to increase the water resistance. A typical method of mixing the composition of the invention is to first mix the fuel with prill nitrate and then mix the thickener and the water repellent material. There is only description that the thickener and the water-repellent substance are added separately or mixed in advance, which is different from the method of forming the wax film of the present invention and then adding the thickener powder. To form a wax film, it is necessary to first dissolve the wax by heating, or emulsify or dissolve it in water or a suitable solvent. In addition, operations such as rotating the explosive particles to be coated and the like are required at the time of film formation.

An object of the present invention is to form a wax film having a melting point of 60 ° C. or more only on the surface of porous prill nitrate, a powder explosive containing ammonium nitrate as a main component, or a granular explosive containing ammonium nitrate as a main component. By adding explosive powder, when the explosive comes in contact with water, water repellency and a barrier of the viscous agent prevent water from entering between explosive particles, providing an explosive with explosive properties and stable detonation It is to be. It is another object of the present invention to reduce the charge of the explosive and improve the fluidity by using a carbon powder such as carbon black or graphite.

[0005]

According to the present invention, a wax film having a melting point of 60 ° C. or more is formed only on the surface of porous prill nitrate, powder explosives mainly composed of ammonium nitrate, or granular explosives mainly composed of ammonium nitrate. And an explosive to which a thickener powder is added.

In the explosive of the present invention, since a water-repellent wax film is formed on the entire surface of the explosive particles, when the explosive comes into contact with water through water holes or the like, the penetration of water between the explosive particles is suppressed. Is done. During that time, the thickener in contact with water forms a strong barrier, which can prevent further ingress of water for extended periods of time. Eventually, the amount of water permeation is reduced as compared with the case where there is no water repellent substance. In the absence of a water-repellent substance, the barrier formation time of the thickener is long, so that the amount of water penetrating into the explosive increases, and the possibility of being affected by water increases. In other words, the explosive dissolves by water, the detonation decreases due to the presence of water, which is an inert substance, etc., and the explosive drops below the limit diameter and stops detonation, or the explosive is completely dissolved and cannot be detonated There are cases.

[0007] Waxes are inexpensive, easy to handle and abundant in variety, including carnauba wax, paraffin wax,
Simple waxes such as microcrystalline wax, and those blended with polyethylene, ethylene-vinyl acetate copolymer, polybutadiene, petroleum resin, polybutene, rosin, cumarone resin, cumarone-indene-styrene copolymer, etc. . Among them, paraffin wax is inexpensive and has the highest water repellency. Further, the compounded wax containing the resin can improve the flexibility and strength of the wax film. In the present invention which forms a thin film since only a limited amount of coating can be used due to oxygen balance, the compounded wax is an effective wax. Further, in consideration of blocking during transportation and storage, wax having a melting point of 60 ° C. or more is suitable. Since the wax is a mixture of hydrocarbons having different carbon numbers, the melting point (JIS K 223) usually referred to in the wax is used.
5-5.3) and a temperature at which the wax is gradually heated to start melting (melting start temperature). Therefore, the wax used in the present invention preferably has a melting onset temperature of 60 ° C.
The above is good.

[0008] The formation of the wax film using a pan coating device, a rolling coating device, a fluidized bed coating device, a composite coating device, etc., for example, a method in which wax is gradually sprayed and added to porous prill nitrate or an explosive and coated. There is.

There is also a method in which powdery wax is mixed with porous prill nitrate or an explosive, and the wax is melted and coated. In addition, if a dense water-repellent coating is not required when it is already coated with another substance to add water resistance, complicated operations and special devices are not required, and the explosive is used as a wax solution. After being pickled and taken out, it may be cooled or dried so as not to aggregate.

When forming the wax coating on the surface of the porous prill nitrate particles, care must be taken so that the wax does not penetrate into the interior of the porous prill nitrate particles. This is because the porous shape greatly affecting the detonation reaction is reduced, and the water repellency is further reduced.

Since the inside of the porous prill nitrate is porous, if the wax easily penetrates into the inside during coating, it is necessary to add a powdery substance. The powdery substance blocks the pores present on the surface of the porous prill nitrate, which is the entrance of the wax, and keeps the wax attached to the powdery substance itself, and further suppresses the fluidity of the wax during coating. The powdery substance may have any shape or size as long as it closes the pores and suppresses the fluidity of the wax, but the shape is preferably plate-like, scale-like, or complex. With such a shape, the film strength of the wax can be improved in an appropriate addition amount range. The powdery substance is, for example, calcium carbonate, silica, talc, carbon black, graphite, metal oxide, atomized aluminum powder,
Flake aluminum powder, magnesium powder, unexpanded shirasu microballoon, expanded shirasu microballoon, glass microballoon, polyethylene beads and the like.

An example of a method for forming a wax film will be described below. When the wax is added as a powder, for example, the wax and talc are mixed with porous prill ammonium nitrate, and the mixture is gradually heated to the melting start temperature of the wax. At the melting start temperature, not all of the wax is melted, and the high viscosity and the presence of talc can prevent infiltration into the porous prill nitrate. The melting onset temperature can be easily determined visually by observing the movement of the mixture of porous prill nitrate and wax. For example, when using a pan coating device,
Below the melting start temperature, the rotating motion of the mixture of porous prilled ammonium nitrate and wax is in a smooth state, but when reaching the melting starting temperature, the rotating motion becomes resistive. The heating time should not be longer than necessary to prevent the wax from entering the inside of the porous prill nitrate. In this method, it is important to control the heating temperature and the heating time so that the wax does not enter the inside of the porous prill nitrate.

When the wax is added to the explosive in a molten state, the wax is heated to maintain the molten state. For example, in the case of an explosive using porous prill nitrate, after the wax adheres to the porous prill nitrate particles, the inside of the particles is heated. Porous prill nitrate must always be kept below the melting point of the wax, as it must be cured immediately so as not to penetrate the wax.

When the wax is emulsified, dispersed or dissolved in water or a solvent and added to the explosive, for example, in the case of an explosive using porous prill nitrate, the emulsion, dispersion, or solution adheres to the porous prill nitrate, and then the particles are removed. Since the water or the solvent must be immediately evaporated so as not to enter the inside, the porous prill nitrate needs to be heated.

When a thickener powder such as guar gum is added to an explosive coated with wax, separation occurs only with the thickener powder. Therefore, for example, there is a method of adding guar gum while coating the wax. At this time, care must be taken that the wax does not coat the guar gum. If the wax covers the guar gum, the guar gum cannot react with the water and cannot form a barrier to prevent water intrusion. After the coating of the wax is completed, the wax coating is wetted with a small amount of liquid and the viscous agent powder is added, or is mixed with the viscous agent powder in advance and added. The liquid is preferably one that does not dissolve the wax film, but can be used if, for example, gas oil is saturated with wax in advance. It is better to use alcohol or ketone. Wax is hardly soluble in polar solvents such as alcohols and ketones. For example, when glycerin is used, it can be used after being saturated with wax.

The thickener used in the present invention is preferably guar gum, or a mixture of guar gum and borax.
Casein, gelatin, starch, gum arabic, sodium alginate, carrageenan, agar, pectin, xanthan gum, guar gum, cycldextrin, juran gum, tamarind seed polysaccharides, tannic acid, tragacanth gum, furceleran, pullulan, locust bean gum, etc. Molecules, carboxymethylcellulose, carboxymethylcellulose nitrate, hydroxyethylcellulose, hydroxypropylcellulose, cellulose derivatives such as methylcellulose, polyacrylamide, sodium polyacrylate, polyacrylamine, polyethyleneimine, polyethylene oxide, polyethylene glycol, polyvinyl alcohol,
Water-soluble synthetic polymers such as polyvinyl methyl ether, polyvinyl pyrrolidone, and propylene glycol can be used.

In addition, since static electricity is generated during the loading of explosives and the use of an electric detonator may cause explosion and is dangerous, the charging of the explosive is prevented by adding carbon powder such as carbon black or graphite. Can be prevented. Since carbon powder such as carbon black or graphite is a hydrophobic substance, it does not impair the water repellency, which is the object of the present invention. Further, they also have an effect as an anti-blocking agent, and can improve the flowability of the explosive.

In addition, calcium carbonate, silica, talc, carbon black, or graphite may be used as an anti-blocking agent after wax coating and addition of a thickener.
Metal oxides and the like can be added.

For the purpose of improving the reactivity, a metal powder such as aluminum or magnesium can be added. Pigment aluminum is coated with water-repellent stearic acid, and can be added without impairing the water-repellency of the explosive.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to Examples and Comparative Examples.

Evaluation method 1 Water resistance test 25 g of the explosive of the example or the comparative example was put into a measuring cylinder having an inner diameter of 30 mm, and 10 g of glass beads having a diameter of 3 to 4 mm were put from above. Further, 25 g of water was gradually added over 30 seconds, and after 1 hour, the water penetrated into the explosive layer, and the volume of the barrier formed by reacting with the thickener was measured from the scale of the measuring cylinder. Since the amount of water penetration is the same as the volume of the formed barrier, the value of this volume can be used to evaluate the water resistance.

Evaluation method 2 Charging test 100 g of the explosives of Examples and Comparative Examples were 15 cm × 25 cm.
Was shaken 100 times in a polyethylene bag, and whether or not it adhered to the surface of the polyethylene bag due to charging was checked.

Example 1 Using a pan coating apparatus, the air flow rate was 50 m ³ / h.
The temperature was adjusted from 50 ° C. to 55 ° C. at 40 r. p. Spray 30 g of 100 ° C. molten paraffin wax (trade name: Paraffin Wax 155 (melting point: 69 ° C.), 100 ° C.) onto 470 g of porous prill nitrate rotating at m at a flow rate of 5 g / min. After spraying, 5
Heated from 8 to 62 ° C and maintained for 5 minutes. Immediately thereafter, 25 g of a mixture of guar gum and borax (weight ratio 9/1) was added,
Rotate the pan at 50 ° C to 55 ° C for 20 minutes (10 rpm).
m) After continuing, the mixture was gradually cooled naturally to obtain a granular explosive.
Here, 30 g of talc was sprayed simultaneously with the spray of the wax. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

Example 2 Using a pan coating apparatus, air flow rate was 25 m ³ / h
The temperature was adjusted from 50 ° C. to 55 ° C. at 40 r. p. 470 g of porous prill nitrate rotating at m., and paraffin wax (trade name: Paraffin Wax 1 manufactured by Nippon Seiro Co., Ltd.)
30 g of 55 (melting point 69 ° C.) or less 60 mesh or less
And 30 g of talc were added in advance, and the mixture was heated from 58 ° C. to 62 ° C. and maintained for 5 minutes. Immediately thereafter, 25 g of a mixture of guar gum and borax (weight ratio 9/1) was added, and 50 g of the mixture was added.
Rotate pan at 10 ° C to 55 ° C for 20 minutes (10 rpm)
Then, the powder was cooled naturally to obtain a granular explosive. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

Example 3 Using a pan coating apparatus, air flow rate was 25 m ³ / h
The temperature was adjusted from 50 ° C. to 55 ° C. at 40 r. p. A mixture of 470 g of porous prill nitrate, which is rotating at m, and 30 g of powder of microcrystalline wax (trade name: 155 microwax (melting point: 70 ° C.) manufactured by Nippon Oil Co., Ltd .; Add,
Heated from 58 ° C to 62 ° C and maintained for 5 minutes. Immediately thereafter, 25 g of a mixture of guar gum and borax (weight ratio 9/1) was added, and the pan was rotated at 50 to 55 ° C. for 20 minutes (10 r.p.m.).
p. m) After continuing, the mixture was gradually cooled naturally to obtain a granular explosive. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

Example 4 An air flow rate of 25 m ³ / h using a pan coating apparatus
The temperature was adjusted from 55 ° C. to 60 ° C. at 40 r. p. Powder of paraffin wax (trade name: POLYCOAT-2253, manufactured by Nippon Seiwa Co., Ltd., product name: POLYCOAT-2253 (melting point: 90 ° C.)) mixed with 470 g of porous prill nitrate, which is rotating at m, and ethylene / vinyl acetate copolymer 30g and talc 3
0 g was added in advance, and 62 ° C.
Heated to 5 ° C and maintained for 5 minutes. Immediately thereafter, 25 g of a mixture of guar gum and borax (weight ratio 9/1) was added, and the pan was continuously rotated (10 rpm) at 55 ° C. to 60 ° C. for 20 minutes. Obtained. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

Example 5 Using a pan coating apparatus, the air flow rate was 75 m ³ / h.
The temperature was adjusted from 65 ° C to 70 ° C with 30 r. p. Porous prill nitrate coated with polyvinyl alcohol (weight ratio 6/94) made by the same method as Comparative Example 2 rotating at m
A mixture (microcrystalline wax (trade name: Hi-Mic-2095, manufactured by Nippon Seiro Co., Ltd., Hi-Mic-2095 (melting point: 98 ° C.)) emulsified at 470 g at an emulsification temperature of 110 ° C. 20% by weight / 77% by weight of water / surfactant (Manufactured by Kao Corporation, trade name: Emulgen 106) 3% by weight) 50 g at a flow rate of 10 g
/ Min, 25 g of a mixture of guar gum and borax (weight ratio 9/1) was added immediately after the spraying, and the pan was continuously rotated (10 rpm) for 20 minutes. I got In addition, 5 g of talc was added to the emulsified mixture. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

Example 6 Using a pan coating apparatus, the air flow rate was 50 m ³ / h.
The temperature was adjusted from 50 ° C. to 55 ° C. at 40 r. p. Spray 30 g of 100 ° C. molten paraffin wax (trade name: Paraffin Wax 155 (melting point: 69 ° C.), 100 ° C.) onto 470 g of porous prill nitrate rotating at m at a flow rate of 5 g / min. After spraying, 5
Heated from 8 to 62 ° C and maintained for 5 minutes. Immediately thereafter, 25 g of a mixture of guar gum and borax (weight ratio 9/1) and 5 g of carbon black were added, and the pan was continuously rotated (10 rpm) at 50 ° C. to 55 ° C. for 20 minutes, and then gradually cooled naturally. This gave a granular explosive. Here, 30 g of talc was sprayed simultaneously with the spray of the wax. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

Example 7 An air flow rate of 25 m ³ / h using a pan coating apparatus
The temperature was adjusted from 50 ° C. to 55 ° C. at 40 r. p. 470 g of porous prill nitrate rotating at m., and paraffin wax (trade name: Paraffin Wax 1 manufactured by Nippon Seiro Co., Ltd.)
30 g of 55 (melting point 69 ° C.) or less 60 mesh or less
And 30 g of talc were added in advance, and the mixture was heated from 58 ° C. to 62 ° C. and maintained for 5 minutes. Immediately thereafter, 25 g of a mixture of guar gum and borax (weight ratio 9/1) and 5 g of carbon black were added, and the pan was continuously rotated (10 rpm) at 50 ° C. to 55 ° C. for 20 minutes, and then gradually cooled naturally. This gave a granular explosive. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

Example 8 Using a pan coating apparatus, air flow rate was 25 m ³ / h
The temperature was adjusted from 50 ° C. to 55 ° C. at 40 r. p. A mixture of 470 g of porous prill nitrate, which is rotating at m, and 30 g of powder of microcrystalline wax (trade name: 155 microwax (melting point: 70 ° C.) manufactured by Nippon Oil Co., Ltd .; Add,
Heated from 58 ° C to 62 ° C and maintained for 5 minutes. Immediately thereafter, 25 g of a mixture of guar gum and borax (weight ratio 9/1) and 5 g of carbon black were added, and the pan was continuously rotated (10 rpm) at 50 ° C. to 55 ° C. for 20 minutes, and then gradually cooled naturally. This gave a granular explosive. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

Example 9 Using a pan coating apparatus, the air flow rate was 25 m ³ / h.
The temperature was adjusted from 55 ° C. to 60 ° C. at 40 r. p. Powder of paraffin wax (trade name: POLYCOAT-2253, manufactured by Nippon Seiwa Co., Ltd., product name: POLYCOAT-2253 (melting point: 90 ° C.)) mixed with 470 g of porous prill nitrate, which is rotating at m, and ethylene / vinyl acetate copolymer 30g and talc 3
0 g was added in advance, and 62 ° C.
Heated to 5 ° C and maintained for 5 minutes. Immediately thereafter, 25 g of a mixture of guar gum and borax (weight ratio 9/1) and 5 g of carbon black were added, and the pan was continuously rotated (10 rpm) at 55 to 60 ° C. for 20 minutes, and then gradually cooled naturally. This gave a granular explosive. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

Example 10 Using a pan coating apparatus, the air flow rate was 75 m ³ / h.
The temperature was adjusted from 65 ° C to 70 ° C with 30 r. p. Porous prill nitrate coated with polyvinyl alcohol (weight ratio 6/94) made by the same method as Comparative Example 2 rotating at m
A mixture (microcrystalline wax (trade name: Hi-Mic-2095, manufactured by Nippon Seiro Co., Ltd., Hi-Mic-2095 (melting point: 98 ° C.)) emulsified at 470 g at an emulsification temperature of 110 ° C. 20% by weight / 77% by weight of water / surfactant (Manufactured by Kao Corporation, trade name: Emulgen 106) 3% by weight) 50 g at a flow rate of 5 g /
min, and immediately after the spraying, 25 g of a mixture of guar gum and borax (weight ratio 9/1) and carbon black 5
g was added and the pan was continuously rotated (10 rpm) for 20 minutes, and then gradually cooled naturally to obtain a granular explosive. In addition,
10 g of talc was added to the emulsified mixture. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

Comparative Example 1 Porous prill nitrate 470 in an aluminum pan
To 30 g, 30 g of light oil was added and mixed to obtain an ammonium nitrate explosive. Further, 25 g of a mixture of guar gum and borax (weight ratio 9/1) was added and mixed. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

COMPARATIVE EXAMPLE 2 An air flow rate of 50 m ³ was used by using Poriac Doria Coat.
/ H, the temperature is adjusted from 80 ° C. to 90 ° C., and 30 r. p.
2.5% to 450g of porous prill nitrate rotating at m
Polyvinyl alcohol (Kuraray Co., Ltd., trade name PV
A-HC) An aqueous solution (2000 g) was sprayed at a flow rate of 20 g / min. (The weight ratio of porous prill nitrate to polyvinyl alcohol is 90/10.) Immediately after spraying, 25 g of a mixture of guar gum and borax (weight ratio 9/1) is added, and the pan is rotated for 5 minutes (10 rpm). This gave a granular explosive. Table 1 shows the results of evaluating this explosive by the above-described evaluation method.

In the water resistance test, Examples 1 to 4 and Examples 6 to 9 were compared with Comparative Example 1 so that Example 5
And Example 10 as compared with Comparative Example 2, it can be seen that the amount of water infiltration was suppressed by adding water repellency. As already explained, the reduction in the amount of water infiltration reduces the amount of explosives affected by water, thereby improving the possibility of stable detonation without losing explosiveness. Further, by adding carbon black to the explosives of Examples 1 to 5, adhesion to polyethylene was eliminated as in Examples 6 to 10, and the chargeability was reduced.

From the above, it can be seen that the water repellency of the wax film and the barrier of guar gum can suppress the penetration of water between the explosive particles. Further, it can be seen that the chargeability is reduced by carbon black.

[0037]

[Table 1]

[0038]

According to the present invention, the melting point is 60 ° C. only on the surface of porous prill nitrate, its powder explosive, or its granular explosive.
By forming the above-mentioned wax film and adding the thickener powder, when the explosive comes into contact with water, the barrier between the water repellent and the thickener suppresses the penetration of water between the explosive particles, and the explosive property and Stable detonation can be maintained. Furthermore, carbon powder such as carbon black or graphite can reduce the charge of the explosive and improve the fluidity.

Claims (3)

[Claims] 1. An explosive in which a wax film having a melting point of 60 ° C. or more is formed only on the surface of porous prilled ammonium nitrate, powder explosive, or granular explosive, and a viscous agent powder is added. 2. The explosive according to claim 1, wherein the thickener comprises guar gum or a mixture of guar gum and borax. 3. The explosive according to claim 1, wherein carbon powder such as carbon black or graphite is added.