JPH08259365A - Granular explosive - Google Patents

Abstract

PURPOSE: To obtain a granular explosive having a high detonation velocity and low initiation sensitivity by compounding granular ammonium nitrate with a specific amount of a fuel oil component. CONSTITUTION: Granular ammonium nitrate having an oil absorption of 15-24% is compounded with a fuel oil component in an amount to get an explosive having an oxygen equilibrium value smaller than -3.4g based on 100g of the explosive. The granular ammonium nitrate preferably has an average particle diameter of 0.2-2.5mm and a hardness of 4-25. Preferably, granular ammonium nitrate having oil absorption of 15-24% accounts for >=20wt.% of the whole granular ammonium nitrate. The oil absorption of the granular ammonium nitrate is measured by immersing a specified amount of ammonium nitrate specimen in a light oil for a prescribed period, filtering the ammonium nitrate under suction and determining the absorption from the difference of the weights before and after the immersion. This granular explosive has high power and safety and is easily handleable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to explosives generally used for industrial blasting operations such as quarrying and mining.

[0002]

2. Description of the Related Art As explosives used in industrial blasting work, dynamite, water-containing explosives, nitrite explosives, ANFO explosives and the like are well known. Especially for quarrying and mining, ANFO explosives have been mainly used in recent years because of their low price, easy handling, and easy loading.

[0003]

The ANFO explosive is a simple explosive in which granular ammonium nitrate (hereinafter referred to as ammonium nitrate) is mixed with a liquid fuel component such as light oil. For this reason, the explosive itself is not highly reactive, and normally exhibits low detonation speed and low sensitivity. In particular, the detonation sensitivity is stipulated by the PVC method or the carton method so that the No. 6 detonator does not completely explode, and because of this low sensitivity, it can be stored and transported in a heavy bag containing 25 kg, for example.

Various methods for improving the reactivity of the ANFO explosive and improving its power have been considered, but as a simple and effective method, the oil absorption rate is 15% to 15% rather than the usual 12%.
There is a method of using granular ammonium nitrate as high as 24%. It has been confirmed that when such granular ammonium nitrate is used in combination with fuel oil, the reactivity of the explosive is improved and the detonation speed is increased. But,
Granular ammonium nitrate of ANFO explosive is 15-24% from normal one
If it is simply changed to the oil absorption rate of No. 6, the detonation sensitivity will be increased at the same time as the detonation speed will be increased, and the PVC or carton method will cause a complete detonation with No. 6 detonator. Therefore, storage and transportation in heavy bags are not allowed, which inevitably increases costs. Thus, the oil absorption rate is 15% to 24%
The method of using granular sodium nitrate certainly shows an increase in detonation speed, that is, improvement in performance, but at the same time, handling becomes complicated, resulting in cost increase, and there is a dilemma that there is no merit of low price and easy handling. It was supposed to fall.

[0005]

As a result of earnest research, the present inventors have used granular ammonium nitrate having an oil absorption rate of 15% to 24%, and the oxygen equilibrium value of the entire explosive is −100 g of explosive.
Addition of fuel oil component to make it more negative than 3.4g increases the detonation speed of explosives, but its detonation sensitivity does not complete with No. 6 detonator by PVC method or carton method. It was found that a low ANFO explosive can be obtained.

That is, the present invention (1) uses granular ammonium nitrate having an oil absorption of 15% to 24%, and the oxygen equilibrium value of the entire explosive is 100 g of explosive.
Granular explosive characterized by blending fuel oil component so that it is more negative than -3.4 g (2) Granular ammonium nitrate having an oil absorption rate of 15% to 24% of the amount of granular ammonium nitrate used in the explosive Two
The explosive described in (1) above, which is used in an amount of 0% or more.

Hereinafter, the present invention will be described in detail. Granular ammonium nitrate used in the explosive of the present invention has an oil absorption of 15% to 24%.
%, Preferably 16% to 20%, with an average particle size of 0.2 mm to 2.5 mm, preferably 0.7 mm
Granular ammonium nitrate having a hardness of 4 to 25 mm and a hardness of 4 to 25 is preferable. In the granular explosive of the present invention, 20% by weight or more of the total granular ammonium nitrate used has an oil absorption of 15 to 2
4% granular ammonium nitrate is preferred.

The oil absorption rate of granular ammonium nitrate is measured by immersing a certain amount of sample ammonium nitrate in light oil for a certain period of time, suction filtration, and observing the oil adsorption amount from the weight difference before and after the test. Specifically, 50 g of the sample glass is put in a glass filter (11G-1) having a diameter of 40 mm and a depth of 50 mm, weighed by an upper plate direct reading balance, and set in a vacuum device. Then, 40 ml of light oil is injected into the glass filter and well stirred with a thin rod to achieve mixed contact of ammonium nitrate and light oil. After leaving for 5 minutes, the lower cock attached to the glass filter is opened and the light oil is allowed to flow down for 2 minutes. Subsequently, after suctioning for 5 minutes with a vacuum pump (flow rate of about 30 l / min), the glass filter containing the sample ammonium nitrate adsorbing the light oil is weighed with a direct plate balance. The increased amount is the light oil adsorption. After the above measurement is finished, the ratio (%) of the light oil adsorption content (g) to the original sample ammonium nitrate 50 g is displayed as the oil absorption rate (%). The calculation formula is as follows. The above is based on the Industrial Explosives Association Act.

Oil absorption rate (%) = light oil adsorbed content (gr) / sample 50 (gr) × 100

The oil absorption rate of granular ammonium nitrate depends mainly on the volume and effective diameter of the pores distributed inside the grain. For example, if the pore volume is large, there is a space for holding light oil inside the grain. Since it becomes large, the oil absorption becomes large. It is a generally known fact that the pore volume and the oil absorption have a substantially direct correlation.

The so-called porous ammonium nitrate having a large number of pores inside the particles is granulated mainly by passing a high temperature ammonium nitrate melt having a regulated concentration through an injection granulator (prilling granulator or prilling tower). It is manufactured on an industrial scale through subsequent drying and cooling processes. In this manufacturing process, the pore volume, the effective pore diameter, etc. are greatly controlled by the raw material conditions such as ammonium nitrate concentration and the melt temperature in the granulation process and the operating conditions of the granulating device and the drying device. By adjusting this appropriately, a desired oil absorption can be obtained.

The average particle size of granular ammonium nitrate is measured from the weight distribution of each sieve after passing a certain amount of ammonium nitrate through various sieves having different meshes.

The hardness of granular ammonium nitrate is measured by mechanically crushing a certain amount of sample ammonium nitrate under a certain condition with a hardness measuring device and observing the amount of crushed ammonium nitrate. The device used for the measurement is a pan (diameter 200 m) that rotates with a rotation shaft that is horizontally fixed on a vertical rotation shaft that rotates through a reduction gear.
m) and a non-rotatable grinding plate (diameter 190 mm, weight 1715 g) that is placed on top of this pan and is not rotated. Put 50 g of sample glass in the pan of hardness tester,
Spread evenly over the entire surface of the plate, stack a grinding plate on it, and activate the device. After a certain period of time, stop the device, and after standing still,
The sample in the tray is taken out, put into a predetermined sieve, and shaken for 1 minute using a shaker. Then, a crushed product that has passed through the sieve is collected, weighed, and the ratio (%) of the crushed amount (g) to 50 g of the original sample ammonium nitrate is expressed as hardness (%).
The calculation formula is as follows. The above is based on the method specified by the Industrial Explosives Association Law.

Hardness (%) = Crush amount (gr) / Sample 50
(Gr) x 100

In the explosive of the present invention, the fuel oil component used by mixing with granular ammonium nitrate is the fuel oil component which is liquid at the time of mixing. Specific examples of the fuel oil that can be used include No. 2 light oil, mineral oil such as kerosene, vegetable oil, and animal oil. Other than these, alcohols, waxes, synthetic polymers, nitro compounds and the like can be used as fuel oils alone or in combination. The fuel oil component having a high melting point can be used by mixing it with granular ammonium nitrate at a temperature above the temperature at which it becomes liquid.

The fuel oil component used in the present invention may be an amount such that the oxygen equilibrium value of the entire explosive is more negative than -3.4 g per 100 g of explosive, but more preferably -3.4 g to -40 g of oxygen. Fuel oil components are used to achieve equilibrium values. The oxygen equilibrium value of explosives is, for example, “New Edition Industrial Explosives” published by the Japan Industrial Explosives Society in 1985, pages 11 to 13 and “Explosive Handbook” published in 1987 by the Industrial Explosives Association, pages 6 and 28 to 29. As described in, the calculation was performed for each component contained in 100 g of explosive, assuming that a complete oxidation reaction occurs, and the excess and deficiency of oxygen in the entire explosive is expressed in g. .

The explosives of the invention are well known to those skilled in the art.
Oxidants other than granular ammonium nitrate, if necessary, wood powder,
It is possible to add powdered fuel such as aluminum powder or other additives.

The explosive of the present invention is generally obtained by adding granular ammonium nitrate to a mixer such as a kneader or a rotary mixer and adding and mixing the fuel oil components while stirring to make the mixture uniform. Other mixers can be used as long as they have the functions of stirring and mixing.

When a fuel oil component having a high melting point is used,
Mixing is performed using a mixer equipped with a heating and heat retaining device. Generally, a desired mixture can be obtained by mixing at a rotation speed of about 20 rpm to 120 rpm for about 2 minutes to 20 minutes.

[0020]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, parts means parts by weight. Further,% is% by weight.

Example 1 92 parts of granular ammonium sulfate having an oil absorption rate of 16% was transferred to a horizontal kneader equipped with a sigma blade at room temperature, and 8 parts of room temperature No. 2 light oil was added,
The mixture was mixed at 80 rpm for 7 minutes to obtain the granular explosive of the present invention.

Example 2 88 parts of granular ammonium sulfate having an oil absorption rate of 20% was transferred to a room temperature concrete mixer, 12 parts of room temperature No. 2 light oil was added, and 100 parts were added.
The mixture was mixed at rpm for 5 minutes to obtain the granular explosive of the present invention.

Example 3 25 parts of granular ammonium sulfate having an oil absorption rate of 20% and 68 parts of granular ammonium sulfate having an oil absorption rate of 12% were transferred to a concrete mixer at room temperature, 7 parts of room temperature No. 2 diesel oil was added, and mixed at 60 rpm for 10 minutes. , A granular explosive of the present invention was obtained.

Comparative Example 1 94 parts of granular ammonium nitrate having an oil absorption rate of 12% were transferred to a horizontal kneader equipped with a sigma blade at room temperature, and 6 parts of room temperature No. 2 light oil was added,
Mixing at 80 rpm for 7 minutes gave the explosive for comparison.

Comparative Example 2 94 parts of granular ammonium nitrate having an oil absorption rate of 16% was transferred to a room temperature concrete mixer, 6 parts of room temperature No. 2 light oil was added, and 100 r was added.
Mix for 5 minutes at pm to obtain the explosive for comparison.

Comparative Example 3 92 parts of granular ammonium nitrate having an oil absorption rate of 12% was transferred to a concrete mixer at room temperature, 7 parts of room temperature No. 2 light oil was added, and 60 rp was added.
and mixed for 10 minutes to obtain a comparative explosive.

The granular explosives of Examples 1 to 3 and Comparative Examples 1 to 3 were tested by the detonation speed test method specified in JIS-K4810. However, No. 6 electric detonator and 30 g of water-containing explosive Kayamite manufactured by Nippon Kayaku Co., Ltd. were used for detonation. Next, these granular explosives were tested by the detonation sensitivity test method A (PVC method) defined in JIS-K4826. No. 6 electric detonator was used for detonation.

Table 1 shows the compositions of the granular explosives of Examples 1 to 3 and Comparative Examples 1 to 3, the oxygen equilibrium value, the above-mentioned detonation speed test results and detonation sensitivity test results.

[0029]

[Table 1] Table 1 Examples Comparative Examples Composition 1 2 3 1 2 3 Granular ammonium nitrate with an oil absorption rate of 16% 92 94 Granular ammonium nitrate with an oil absorption rate of 20% 88 25 Granular ammonium nitrate with an oil absorption rate of 12% 68 94 92 No. 2 diesel oil 8 12 7 6 6 8 Oxygen equilibrium value (g / 100g) −9.0 −23.6 −5.4 −1.7 −1.7 −9.0 Performance Explosion velocity (m / sec) 3300 3200 3200 2700 3300 2700 Initiation sensitivity test result Incomplete explosion Incomplete explosion Incomplete explosion Incomplete explosion Incomplete explosion Incomplete explosion (PVC method)

The explosive of the present invention of Examples 1 to 3 has an explosive velocity of 32.
In comparison with Comparative Examples 1 and 3, the detonation sensitivity was low at an incomplete detonation of No. 6 detonator, but the detonation speed was low at 2700 m / sec, while the detonation sensitivity was 0 to 3300 m / sec. Although the detonation speed is as high as 3300 m / sec, the detonation sensitivity is as high as a complete detonation in No. 6 detonator, and it can be seen that only the explosive of the present invention exhibits the characteristics of high detonation speed and low sensitivity.

[0031]

EFFECTS OF THE INVENTION A granular explosive having a high detonation speed and a low detonation sensitivity can be obtained. Since this granular explosive is powerful and safe, it can be handled easily.

Claims (2)

[Claims] 1. A granular ammonium nitrate having an oil absorption of 15% to 24% is used, and the oxygen equilibrium value of the entire explosive is explosive 1.
Granular explosive characterized by blending fuel oil component so that it is more negative than -3.4 g per 00 g. 2. The explosive according to claim 1, wherein the granular ammonium nitrate having an oil absorption rate of 15% to 24% is used in an amount of 20% or more of the amount of the granular ammonium nitrate used in the explosive.