JP2002173389A - Granular explosive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a granular explosive composition for controlled blasting having good properties to propagate detonation and stability with lapse of time. SOLUTION: This granular explosive composition contains porous prill ammonium nitrate and inorganic foam of 0.65 to 0.73 in bulk specific gravity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a granular explosive composition used for controlled blasting in industrial blasting such as crushed stone, mining, and tunnel excavation for the purpose of reducing vibration and noise during blasting.

[0002]

2. Description of the Related Art Conventionally, there has been an ammonium nitrate explosive (hereinafter abbreviated as ANFO) as an explosive composition mainly composed of porous prill ammonium nitrate. Porous prill nitrate refers to porous granular ammonium nitrate, and ANFO is an explosive obtained by mixing this porous prill nitrate with light oil. ANFO can be easily manufactured with a simple device, and because of its excellent fluidity, it can be directly poured into a blast hole, can be loaded with an ANFO loader, has low impact sensitivity, is safe, and is inexpensive. It is widely consumed for such reasons. A low specific gravity substance having a specific gravity smaller than that of porous prilled ammonium nitrate is mixed with the ANFO to lower the bulk specific gravity and the explosion velocity, and is generated at the time of blasting due to a decrease in the amount of charge into the blast holes and a decrease in the explosive power of the explosive composition itself. There are explosive compositions that reduce vibration and noise and increase the size of crushed rock.

For example, Japanese Patent Application Laid-Open No. 62-132793, Japanese Patent Application Laid-Open No. Hei 8-26877, Australian Patent No. 8784231, Australian Patent No. 87
No. 81802, U.S. Pat. No. 5,409,556, in which inorganic low specific gravity substances such as shirasu balloon, perlite, vermiculite, wood flour, polystyrene,
There is disclosed an explosive composition in which an organic low-specific-gravity substance such as polyethylene, polypropylene, charcoal powder, rubber particles, cotton wool, foamed rice, and foamed wheat is mixed.

[0004] These explosive compositions have a bulk specific gravity and explosive velocity suitable for controlled blasting, but the energy density of inorganic substances having a low specific gravity is lower than that of ANFO, and oxidizing agents of organic substances having a low specific gravity. Is poor in mixing the porous prill nitrate and the organic low specific gravity substance as the fuel.
Therefore, the explosive composition has a larger critical diameter than ANFO and has a lower explosiveness, and the explosive composition becomes moist within the blast hole.
Or a normal ANF, such as a partial dissolution
If it is O, detonation is often interrupted even if the amount of infiltrated water enters without any problem.

[0005] In addition, when mixing ANFO and low-specific-gravity substances in actual production, or when transporting the product, low-specific-gravity substances or porous prill nitrate are powdered, and the low-specific-gravity substances and ANFO are separated, so that the explosiveness deteriorates. Detonation interruption occurs. Furthermore, the liquid fuel adsorbed on the porous prill nitrate moves to a substance having a lower specific gravity with the passage of time, and the explosion speed decreases due to the deterioration of the mixing property between the oxidant and the fuel. As a result, the crushing effect is deteriorated, and the detonation is more easily interrupted.

[0006]

SUMMARY OF THE INVENTION The present invention solves the problems relating to the detonation interruption and the stability with time of the prior art, and provides a granular explosive composition for controlled blasting having excellent explosiveness and stability with time. It is intended to do so.

[0007]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a granular explosive composition containing liquid fuel and a low-specific-gravity substance containing porous prill nitrate as a main component. In a product, (1) Even if the bulk specific gravity of porous prill nitrate is reduced, the explosive property is not affected. If porous prill nitrate having a small bulk specific gravity is used, the explosive property is improved by reducing the amount of low specific gravity substance added. Is possible,
(2) If the surface of the low-specific-gravity substance is smooth or spherical or ellipsoidal, powdering during production or transportation of the product is unlikely to occur, and (3) the oil absorption of the low-specific gravity substance decreases. The present inventors have found that the longer the stability with time, the better the invention.

That is, the present invention relates to (1) a granular explosive composition comprising, as a main component, porous prill nitrate, a liquid fuel and a low specific gravity substance, wherein the porous prill nitrate has a bulk specific gravity of 0.65 to 0.5. 73. (2) A granular explosive composition comprising, as a main component, porous prill nitrate, a liquid fuel and a low specific gravity substance, wherein the low specific gravity substance has a smooth surface. An explosive composition characterized by the fact that (3) porous prill nitrate is a main component,
A granular explosive composition containing a liquid fuel and a low specific gravity substance, wherein the low specific gravity substance has an oil absorption of 0.1 to 25% by weight.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below. The bulk specific gravity of porous prill nitrate in the present invention is 0.65.
~ 0.73 is preferred. If it is 0.73 or less, the amount of the low specific gravity substance necessary for lowering the bulk specific gravity of the explosive composition can be suppressed to a range where the explosiveness is not deteriorated.
If it is less than 5, the strength will decrease due to the increase in voids in the porous prilled nitric acid, and it will be pulverized during the mixing process with the low specific gravity material in actual production or during transportation of the product. Easier to do. More preferable bulk specific gravity of porous prill nitrate is 0.67 to 0.71.

The low specific gravity substance is preferably a nonflammable inorganic foam. This is because the explosion velocity suitable for controlled blasting can be obtained even when the porous prill nitrate having the bulk specific gravity is used and the amount added is reduced to a range where the explosiveness does not deteriorate. If the low specific gravity substance is flammable, it contributes to the combustion reaction.
If the amount of addition is within the range that does not deteriorate the explosiveness, it is not possible to obtain an explosion velocity suitable for controlled blasting. Addition amount of low specific gravity substance is 5
Less than 10% by weight is preferred. Within this range, the explosiveness does not deteriorate, and it is possible to obtain a bulk specific gravity suitable for controlled blasting by using porous prill ammonium nitrate having the above bulk specific gravity, but more preferably 5 to 9 weight%
It is.

The bulk specific gravity of the low specific gravity substance is preferably 0.3 to 0.5, because if the difference from the bulk specific gravity of porous prill nitrate is large, the substance will be separated. The low specific gravity substance preferably has a smooth surface, and more preferably has a substantially spherical shape. In contact with porous prill nitrate or contact between low-specific-gravity substances, stress concentration in the uneven portion of the surface is small, and the strength of the low-specific-gravity substance itself is increased, so that powdering during manufacturing and transportation can be eliminated. . As a result, there is no separation between the porous prill nitrate and the low-specific-gravity substance, so that detonation interruption is less likely to occur.

Further, the lower the specific gravity of the substance, the lower the oil absorption, the more preferable. Since the liquid fuel adsorbed on the porous prill nitrate does not move to the low specific gravity material side, a decrease in the explosion speed can be suppressed. Oil absorption of low specific gravity substance is 0.1 ~ 2
The content is preferably 5% by weight, and if it is in this range, the problem relating to stability over time can be almost solved. More preferably, 0.1 to 2
0% by weight, more preferably 0.1 to 15% by weight
It is. The type of the low specific gravity substance is not particularly limited, but a substance satisfying the surface shape and the oil absorption is preferable. As such a low specific gravity substance, there is an inorganic foam mainly composed of silica and alumina. For example, pearlite obtained by heating and expanding obsidian, and shirasu balloon obtained by heating and expanding volcanic glass particles in shirasu are used. The explosive composition of the present invention may be one to which calcium carbonate, silica, talc, carbon black, graphite, metal oxide, or the like is added as a blocking resistance agent and a flowability improver.

The oil absorption in the present invention is the percentage by weight of No. 2 gas oil adsorbed on the low specific gravity substance when a low specific gravity substance is put into a glass filter and No. 2 gas oil is added. For details, first, the diameter was 40 mmφ,
A low specific gravity substance is put into a Buchner funnel type glass filter having a content of 60 cc to a height of 40 mm from the upper surface of the filter plate to measure the total weight. Next, a rubber tube whose hole was closed with a pinch cock was attached to the end of the glass filter, and No. 2 light oil was added until the low-specific-gravity substance completely sank, and the mixture was allowed to stand for 5 minutes. After standing, remove the rubber tube and let No. 2 light oil fall naturally for 2 minutes, and connect it with a vacuum pump and suck it for 5 minutes. After the suction is completed, the oil is removed from the vacuum pump, the total weight is measured, and the oil absorption is calculated by the following equation. Oil absorption (outer weight%) = (W2- (W1-W0) -W0
−0.1) / (W1−W0) × 100 W0 in this equation is the weight (g) of the glass filter,
W1 is the total weight (g) when the low specific gravity substance is put, W2 is the total weight (g) measured after suctioning the vacuum pump,
0.1 is a correction value of No. 2 light oil adhering to the wall surface of the glass filter.

The bulk specific gravity in the present invention is a value calculated from the volume and weight when a sample is placed in a glass measuring cylinder. Specifically, first, a sample is put into a 100 cc glass measuring cylinder, which has been weighed in advance, so that the upper surface thereof reaches a scale position of approximately 80 cc, and the total weight is measured. Next, the bottom of the measuring cylinder is lightly tapped 20 times on a cloth to level the upper surface of the sample, and then the volume of the sample is measured using the scale of the measuring cylinder. The bulk specific gravity is calculated from the following equation. Bulk specific gravity = (W1-W0) / V W0 in this equation is the weight (g) of the measuring cylinder, W
1 is the total weight (g) after the sample is put, and V is the volume (cc) of the sample measured with a measuring cylinder. Hereinafter, the present invention will be described based on examples, but the present invention is not limited to only these examples.

[0015]

Examples 1, 2, 4 Porous prill nitrate 8 shown in Table 1
6.2% by weight and 5.5% by weight of No. 2 light oil are uniformly mixed,
Next, 8.3% by weight of the low specific gravity substance shown in Table 1 was added and mixed until uniformly dispersed to obtain the explosive composition of the present invention shown in Table 1. Thereafter, tests shown in Tests 1 to 3 were performed using this explosive composition. Table 1 shows the test results. The shapes of the low-specific-gravity substances used in the respective examples are shown in FIGS.

[0016]

Example 3 79.9% by weight of porous prill nitrate and 5.1% by weight of No. 2 light oil shown in Table 1 were uniformly mixed, and then 15.0% by weight of a low specific gravity substance shown in Table 1 was added. By mixing until uniformly dispersed, the explosive composition of the present invention shown in Table 1 was obtained. Thereafter, tests shown in Tests 1 to 3 were performed using this explosive composition. Table 1 shows the test results. FIG. 3 shows the shape of the low specific gravity substance used in this example.

[0017]

Comparative Example 1 94.0% by weight of porous prill nitrate and 6.0% by weight of No. 2 gas oil shown in Table 1 were uniformly mixed, and an explosive composition having the same composition as that of the currently marketed ANFO shown in Table 1 was obtained. Obtained. Thereafter, tests 1 and 2 were performed using this explosive composition.
The test shown in FIG. Table 1 shows the results.

[0018]

Comparative Examples 2 and 3 Porous prill nitrate shown in Table 1 79.
9% by weight and 5.1% by weight of light oil No. 2 were uniformly mixed, and then 15.0% by weight of a low specific gravity substance shown in Table 1 was added.
The prior art explosive compositions shown in Table 1 were obtained by mixing until homogeneously dispersed. Thereafter, tests shown in Tests 1 to 3 were performed using this explosive composition. Table 1 shows the test results. FIG. 3 shows the shape of the low specific gravity substance used in Comparative Example 2.

From the limit drug diameter obtained in Test 2 and the state of pulverization confirmed in Test 3, it is possible to judge whether the explosiveness is good or bad. In other words, as described in the above-mentioned prior art, the larger the critical drug diameter or the more powdered, the worse the explosiveness. Therefore, from Table 1, it is clear that the explosive composition of the present invention has the same bulk density and explosion speed as the conventional explosive composition, but is superior in explosiveness or stability over time. Also, from Table 1 and FIG. 3, it can be seen that the smoother the surface of the low-specific-gravity substance, the less the powder is likely to occur.

[0020]

[Test 1] The explosive velocity of the explosive composition was measured in accordance with the explosive velocity measurement test using an optical fiber specified in JIS K4810 explosive performance test. For detonation, 30 g of No. 2 enoki dynamite was used. The measurement was performed one week, six months, and eighteen months after the explosive composition was obtained.
The test was performed each time.

[0021]

[Test 2] 20A steel pipe (outer diameter 27.2 mm, thickness 2.8) specified in JIS G3452 carbon steel pipe for piping
mm), 25A steel pipe (outer diameter 34.0mm, thickness 3.2m)
m), 32A steel pipe (outer diameter 42.7mm, thickness 3.5m)
m) was filled with an explosive composition, and it was checked whether each of them would be detonated by 30 g of No. 2 enoki dynamite, and the critical diameter was determined. The steel pipes were all 350 mm long, and one opening was closed by welding a steel plate. Further, after the explosive composition was poured into a steel pipe, the bottom of the steel pipe was beaten about 20 times on a plastic plate to be densely filled. One week after the explosive composition was obtained,
The test was performed three times on each steel pipe.

[0022]

[Test 3] 1 kg of the explosive composition was placed in a 5 liter plastic bag, shaken vigorously at an amplitude of about 20 cm for 1 minute, and visually checked for powdering of a low specific gravity substance or porous prill nitrate.

[0023]

[Table 1]

[0024]

The explosive composition of the present invention has good explosiveness and stability over time, and has a bulk density and explosion velocity suitable for controlled blasting, which are the same as those of the prior art explosive composition.

[Brief description of the drawings]

FIG. 1 is a photograph of the inorganic foam used in Example 1 and Comparative Example 2, taken with a Hitachi scanning electron microscope S-2380N.

FIG. 2 is a photograph of the inorganic foam used in Example 2, taken with a Hitachi scanning electron microscope S-2380N.

FIG. 3 is a photograph of the inorganic foam used in Examples 3 and 4 taken with a Hitachi scanning electron microscope S-2380N.

Claims (5)

[Claims] 1. A granular explosive composition comprising porous prill nitrate as a main component, a liquid fuel and a low specific gravity substance, wherein the porous prill nitrate has a bulk specific gravity of 0.65 to 0.73.
An explosive composition comprising: 2. A granular explosive composition comprising porous prill ammonium nitrate as a main component, a liquid fuel and a low specific gravity substance, wherein the low specific gravity substance has a smooth surface or a spherical or elliptical spherical surface. An explosive composition comprising: 3. A granular explosive composition comprising porous prill nitrate as a main component, a liquid fuel and a low specific gravity substance, wherein the low specific gravity substance has an oil absorption of 0.1 to 25% by weight. Explosive composition. 4. The low specific gravity substance has a smooth surface.
The explosive composition according to claim 1, wherein the composition is spherical or elliptical. 5. The explosive composition according to claim 1, wherein the low specific gravity substance has an oil absorption of 0.1 to 25% by weight.