RU2836276C1 - Explosive composition for mechanized loading of blast holes and wells - Google Patents

Abstract

FIELD: blasting.

SUBSTANCE: invention relates to blasting operations and can be used, in particular, in pneumatic method of charging blast holes and wells in underground mining operations. Explosive composition based on granulated ammonium nitrate contains granulated ammonium nitrate, an oil product and a solid combustible component of up to 8 wt.%. Solid combustible component contains polydisperse aluminium and dispersed graphite. Polydisperse aluminium has aluminium particle size of 70-450 mcm. Components of the explosive composition have the following ratio, wt.%: dispersed graphite – 0.5-2.0; polydisperse aluminium – 3-6; oil product – 2-5; granulated ammonium nitrate – balance.

EFFECT: reduction of volume resistance and, as a result, increase of electroconductivity of explosive composition with absorption of static charge, increase of critical threshold of mechanical action, as well as increase of detonation speed of explosives.

2 cl, 4 dwg, 8 tbl

Description

Field of technology

The invention relates to blasting operations and can find its application, in particular, in the pneumatic method of loading boreholes and wells in underground mining operations.

State of the art

From the prior art (RU 2456257 C2, 20.07.2012 - [1]), an explosive composition (black powder) is known, containing crystalline carbon - graphite, introduced in order to reduce the electrification of the material (to eliminate the accumulation of dangerous static electricity potentials) and to increase flowability (to reduce the internal friction of the bulk material).

The solution known from [1], like TNT, has the disadvantage that it does not have a tolerance class for underground work, in particular due to the release of a large volume of hazardous gases with characteristic causticity and toxicity.

Explosives based on ammonium nitrate are safer, and can therefore be used both for underground work in a non-hazardous environment and for blasting in open areas. Thus, explosives based on ammonium nitrate can be used for loading boreholes and boreholes with subsequent use.

The closest analogue of the proposed invention can be granulated explosives (GVE) based on ammonium nitrate (AN) - granulites AN-4, AN-8 (GOST 21987-76 - [2]), containing ammonium nitrate, industrial oil and, as an energy additive, aluminum powder.

In this case, the basis for using aluminum powder in the composition of explosives is the knowledge that the maximum effect of increasing the detonation characteristics from the combustion of aluminum in the chemical reaction zone is achieved with the maximum contact surface (in finely dispersed form) of the combustible component (Al) and the oxidizer ( _O2 ).

However, the main disadvantage of the above industrial explosives is the high fire and explosion hazard during production and use, due to the presence of chemically active finely dispersed aluminum powder in the formulation. It is known that even with slight moisture, finely dispersed aluminum is capable of oxidative exothermic processes, accompanied by the release of hydrogen, and, as a consequence, of ignition and explosion.

Thus, aluminum powder in a suspended state in the air atmosphere (aerosol) is explosive, and in a bulk state it is fire hazardous. According to GOST 5592-71 ([3]), the lower concentration limit of flame propagation (LCFL) of aluminum dust is 40 g/ ^m3 , the autoignition temperature of aerosol is 540°C, dust - 320°C, the minimum ignition energy is 1 mJ.

During the production of granulites, due to the high specific surface area of aluminum powder particles (S _sp ≈ 4000 cm ² /g, d particles ≈ 10 μm), as well as their lamellar shape, complete fixation of particles on the surface of oiled ammonium nitrate granules does not occur. Aluminum powder particles are distributed on the surface of the nitrate granules in several layers and, as a result, during mechanized loading of granulites, intensive removal of aluminum particles and strong dusting are observed, which leads to dustiness of the face and deterioration of sanitary and hygienic working conditions, as well as to a violation of the ratio of components in the composition and, as a consequence, to deterioration of explosive characteristics. Thus, according to known data (Collection “Technology of preparation and application of simple explosives”, Moscow, 1996, pp. 106-114 - [4]), the loss of aluminum powder during pneumatic loading of granulites AC-4, AC-8 amounts to 22% of its content in the composition.

Based on the above, special requirements are imposed on the production of aluminum-containing industrial explosives to ensure safety, complicating the equipment design and control of the technological process.

In addition, granulites AC-4, AC-8 are capable of becoming highly electrified during pneumatic charging, since a dielectric shell of aluminum powder covered with an oxide film of Al ₂ O ₃ is formed on the inner surface of the pipeline, preventing the removal of static electricity charges from the product, which increases the likelihood of ignition despite the measures taken to protect against static electricity (grounding of charging equipment, use of conductive charging hoses, moistening the product with water injected during charging in an amount of up to 5%) (Collection "Technology of Preparation and Application of Simple Explosives", Moscow, 1996, pp. 144-148 - [5]).

At the same time, almost all components of granulated explosives are dielectrics: the volume resistance of ammonium nitrate is 10 ⁷ Ohm⋅m, aluminum powder - 10 ^8-11 Ohm⋅m, oil products - 10 ¹⁵ Ohm⋅m and TNT - 10 ¹² - 10 ¹⁴ Ohm⋅m, which also contributes to the electrification of explosives during the loading process. Thus, in the level of technology there is a task to reduce the ability of granulated explosives to electrify.

The following are used as effective methods for reducing the intensity of static electricity generation, which ensure the dissipation and flow of electrostatic charges from the dielectric materials of explosives: increasing the electrical conductivity of the environment, reducing the surface or volume resistance of electrified surfaces by increasing humidity, using antistatic additives, and applying conductive coatings.

Thus, during pneumatic loading of granulated explosives, wetting (increasing the humidity of the material) is required to reduce surface resistance, ensuring the formation of a wet film on the surface of the particles (clause 711 of the Federal Law “EPB for VR” - [6]).

In this case, the decrease in surface and volume resistance is due to the property of electrical conductivity of saturated solutions of AC, which are always present in AC of any humidity different from zero. The solution of AC in water is a solution of a strong electrolyte, which in a practical sense means the formation of ionic conductivity - conductivity of the second kind.

Due to the fact that with decreasing temperature the electrical conductivity of liquids in general, and petroleum products in particular, decreases, ensuring the electrical conductivity of explosive compositions becomes especially important at negative temperatures, which occurs when developing deposits with permafrost located in the Arctic zone, the importance of developing which increases over time.

A method for reducing the volume resistance of granulated explosives based on AC is known from the patent level of technology (RU 2383520 C1, 10.03.2010 - [7]) by imparting electrical conductivity properties to the petroleum product.

In the solution known from [7], this is achieved by the fact that in the method for preparing granulite, which includes treating granulated ammonium nitrate with an oil product with an antistatic additive dissolved in it, “Crodastat” or “Kerostat 8168”, or “ASP-3” is used as the antistatic additive, the treatment of granulated ammonium nitrate is carried out with an oil product with an antistatic additive dissolved in it, having a specific electrical resistance not exceeding 10 ⁴ Ohm/m, and obtained by introducing an antistatic additive into the oil product in an amount not exceeding 0.0046 wt.% of the weight of the oil product.

In the solution known from [7], the effect of reducing the specific electrical resistance is a consequence of the creation of a conductive film of petroleum product on the surface of the explosive granules, which provides an electronic mechanism for electrical conductivity. Accordingly, the value of the volume resistance of the mixture depends on the thickness or even on the presence of a film of petroleum product on the surface of the granules, and, ultimately, on the amount of petroleum product in the explosive composition.

At the same time, explosives used for underground work must have an oxygen balance close to zero, as a result of which the maximum amount of liquid combustible petroleum product is limited. For example, in the simplest two-component explosive composition, this value should not exceed 5.6%. In three- or more-component compositions containing, in addition to liquid petroleum product, other types of combustible, for example, solid combustible in the form of dispersed aluminum, coal, ferrosilicon, etc., the amount of petroleum product decreases in proportion to the contribution of these combustibles to the overall oxygen balance, and, in most known compositions, does not exceed 4%.

Thus, to ensure the formation of a stable film on all surfaces of the explosive components, the amount of petroleum product components in the explosive is insufficient. This is especially evident when using porous grades of ammonium nitrate, the absorption capacity of which reaches 13%, as a result of which almost all of the petroleum product is absorbed into the granules and the surface becomes dry, without signs of oiling (Mining Industry No. 4, 2020, pp. 84-85 - [8]).

The proposed invention is aimed at overcoming the above-mentioned shortcomings of the state of the art and, when implemented, allows for the achievement of technical results consisting of a reduction in volume resistance and, as a consequence, an increase in the electrical conductivity of the explosive composition with the absorption of static charge, an increase in the critical threshold of mechanical action, and an increase in the detonation velocity of explosives.

Disclosure of invention

In order to achieve the above-mentioned, as well as other technical results that follow from this description for a specialist, an explosive composition based on granulated ammonium nitrate is proposed, containing granulated ammonium nitrate, a petroleum product and a solid combustible component up to 8 wt.%, characterized in that the solid combustible component contains polydisperse aluminum and dispersed graphite, wherein the polydisperse aluminum is made with a fraction size of aluminum particles of 70-450 μm, and the components of the explosive composition have the following ratio, wt.%:

dispersed graphite 0.5-2.0 dispersed graphite 0.5-2.0 polydisperse aluminum3-6 polydisperse aluminum3-6 petroleum product2-5 petroleum product2-5 granulated ammonium nitrate rest anuled ammonium nitrate rest

In additional embodiments, the granulated ammonium nitrate is selected from: non-water-resistant, water-resistant, porous, non-porous, or is a mixture of the said granulated ammonium nitrates, and the petroleum product is diesel fuel, industrial oil, or a mixture thereof.

Further in the description, more detailed information is presented regarding the implementation of the proposed invention, and a justification for achieving the above-mentioned technical results is also provided.

Implementation of the invention

The proposed composition of explosives is intended for production at stationary points for the production of granulated industrial explosives.

In order to create a granulated explosive composition with guaranteed electrical conductivity, the proposed invention proposes introducing dispersed graphite into the explosive composition as one of the parts of the combustible component to increase electrical conductivity.

Graphite, which is crystalline carbon, has high electrical conductivity, at the level of metals 10 ^-6 Ohm⋅m and a high ignition temperature of 3700°C. The autoignition temperature of the air suspension of dispersed graphite is from 730 to 970°C.

In addition, as a result of a series of tests, as shown below, it was revealed that the combustion mechanism of aluminum with a polydisperse composition differs from the combustion of particles with a narrow dispersion range. Thus, with the same charge diameters (120 mm), the increase in detonation characteristics from aluminum with a dispersion of 0-450 μm and 0-1000 μm approaches the characteristics inherent in the combustion of powder. Based on this, it can be concluded that the development of the aluminum combustion mechanism in the chemical reaction zone takes on a self-amplifying chain character, with the involvement of increasingly larger particles in the reaction.

During the tests, measurements were made of the detonation characteristics (speed and relative performance) of granulated explosive mixtures of various compositions, in order to substantiate the formulation of the developed explosive composition of industrial explosives with increased (by 15%) indicators of power and safety of use.

The tests were carried out on samples of granulated explosives made on the basis of granulated ammonium nitrate according to GOST 2 - 2013 and porous ammonium nitrate produced by JSC NAK Azot according to TU 20.15.33-073-05761643 using energy additives of various compositions.

When measuring the detonation velocity in explosive charges, the method according to GOST RV-50998-96 (method for determining the explosive transformation velocity) was used. The method is based on determining the average explosive transformation velocity on a certain section of the charge length (base) with recording the time of the explosive process by ionization electric contact sensors of the electric circuit closure (hereinafter detonation sensors).

The size of the measuring base was determined by the required measurement accuracy and the sizes of the ionization detonation sensors. For the permissible spread of the detonation velocity determination ΔD _BB = 100 m/s (~3% for the detonation velocity of 2000-4000 m/s) and the thickness of the ionization sensor of ~2 mm, the measuring base was taken to be no less than 70 mm.

The time of detonation front passage along the base was measured using a multichannel detonation velocity meter ZBS-10 (hereinafter referred to as the ZBS-10 device), which allows determining the detonation velocity in a charge of explosives at 10 bases. The ZBS-10 device includes a computer of the "MCS-51as nuclear parts" series (as a core), a 10 MHz generator (as a reference signal source) and has the required measurement accuracy and operational stability in field conditions.

Relative performance is determined by the method of compressing a lead column (crusher) during the explosion of an explosive charge of a given mass, located at a regulated distance from a massive “anvil”, on a special assembly (methodology of JSC Scientific Center “VostNII”) and in accordance with GOST 14839.19-69.

The assessment of the relative performance of lead crushers using the compression method is based on the dynamic impact of explosion products on the anvil.

The deformation of the crusher under the influence of an explosive load depends on the detonation speed, the mass of the explosive charge, as well as the length of the air gap - the distance from the lower end of the charge to the plane of the anvil, its mass and area.

The assessment of the explosive-mechanical effect of the explosion is based on the principle of a dynamic impulse meter, which produces compression of lead crushers (pillars) of standard size - height, H _o = 60 mm and diameter d _o = 40 mm.

The crusher was placed on a massive steel support. The crusher was compressed under the action of a pulse from a special massive steel anvil with a mass of M = 25 kg, on which the explosive action of the active part of the vertically located elongated explosive charge in a soft shell was applied.

An axial air gap Δl is created between the lower end of the explosive charge and the anvil, the height of which is regulated by means of support posts fixed to the side surface of the cylindrical charge. By changing the height of the air gap Δl, it is possible to control the explosive impulse of the anvil mass impact on the lead crusher.

The impulse communicated to the anvil during the explosion, acting on the crusher, produces its deformation, reducing its height (with a constant volume) proportionally to the mechanical work performed to compress it.

The air gap (damper) allows to reduce the peak pressure at the front of the air shock wave (its head part), which characterizes the brisant effect of the explosion, while the pulsed effect of the explosion, transmitted during the deformation of the crusher by the anvil, has a purely high-explosive nature of the effect, which allows to consider the mechanical work of deformation (compression) of the lead crusher as a measure of the quantitative assessment of the performance of the tested explosive sample.

The measurement of relative performance was carried out using an original method on a stand (assembly), which allows for the measurement of detonation velocity in parallel in one experiment (Fig. 1).

According to the positions in Fig. 1 the following are presented:

1 - support plate; 2 - lead crusher; 3 - anvil; 4 - support posts, air gap; 5 - detonation sensors; 6 - charge in a soft shell; 7 - PD (intermediate detonator); 8 - initiator (ED - electric detonator), NSI - (non-electric initiation system); 9 - stretchers for fixing the explosive charge in a vertical position (if necessary); 10 - cable to the detonation velocity meter, 11 - detonation velocity meter; Δl = height of the axial air gap.

According to theoretical concepts, at Δl ≤ 10d _, the impulse effect of the explosion on the anvil is determined by the mass of the charge Q, the detonation velocity Dвв and, depending on the height of the air axial gap between the end of the charge and the plane of the anvil Δl, is, in accordance with the formula:

(1)

where: A is a constant value depending on the speed of expansion of the explosion products.

Therefore, to obtain the same impulse of the explosion action, and therefore, the same compression of lead crushers, for two different types of explosives it is necessary to observe the ratio:

= , (2)

With the equality of the masses of the studied explosives, for the compression of the crusher Q ₁ = Q _2, the ratio of the values of the axial air gaps should change proportionally to their detonation velocities

= , (3)

In the practice of blasting operations, the efficiency of explosives is usually assessed by the value of the explosive efficiency coefficient, numerically equal to the ratio of the masses of equivalent explosive charges, during the explosion of which the same mechanical work is performed to deform the object being destroyed:

, (4)

Where - mass of measured and reference explosives, kg.

As applied to the process of compression of a lead crusher during an explosion, under the action of a massive anvil impulse, the equation for the balance of deformation energies and the applied impulse load has the form:

, (5)

Where: - resistance to crusher compression;

= H _o - H _k - the value of compression of the lead crusher during explosion, mm;

H _o - initial height of the crusher, mm;

H _k - final height of the crusher, mm;

V _к - volume of the lead crusher, ^mm3 ;

J - the impulse transmitted by a metal anvil during the explosion of an explosive charge;

M – anvil mass, kg.

At constant values of the parameters - σ, V _k and M, the explosion impulse J, acting on the anvil through the air axial gap, with a height of Δl ≤ 10d _vv , according to the research of E.O. Vlasov and M.A. Sadovsky, is taken to be proportional to the mass of the explosive charge - J ~ Q.

In this case, according to equation (1), we obtain a ratio for assessing the relative performance of the explosive used to the reference explosive in the form of an equation that links the masses of equivalent charges with the amount of compression of lead crushers during an explosion:

To _vv = , (6)

Consequently, the coefficient of explosive efficiency of explosives - K _vv during the explosion of charges is uniquely determined by the magnitude of the compression of the crushers by the anvil of equivalent charges of the same mass.

Since the momentum of the explosion (J) is determined by the product of the mass of the explosive (Q) and the speed of its detonation (D), then for two explosives compared by their momentum, an obvious equality can be written:

J = J _e

QD _вв = _{Qэ Dэ} (7)

In equation (7), the index “e” refers to the reference explosive taken as the basis for comparison.

Consequently, for the same explosion impulses of the compared explosives, the value of the explosive efficiency coefficient K _vv is determined only by their detonation velocities, according to a relationship of the type:

K _vv = Q/Q _e = D _e /D _vv (8)

The assessment of the relative efficiency of explosives by the value of the coefficient of explosive efficiency K _vv (4) can be carried out by its experimental determination, both by the value of a direct measurement of the degree of compression of the crusher during an explosion ΔH, and indirectly by determining the detonation velocity D _vv in the explosive charge acting on the anvil during compression of the crusher.

To conduct the tests, explosive mixtures were prepared with a composition that ensured an oxygen balance close to zero.

The production of samples of explosive mixtures of experimental recipes was carried out by manual mixing in buckets with a capacity of 12 l, made of non-sparking material, of weighed portions of components measured with an error of no worse than ± 0.1 g at a measurement limit of 1000 g.

To control the uniformity of distribution of the liquid combustible component in the explosive mixture, DT (diesel fuel) was tinted with Sudan dye.

The measurement of detonation characteristics of experimental formulations of explosive mixtures was carried out using method “A” - in a soft shell, according to GOST 14839.19-69.

The soft shell in the form of a tube was made of wrapping paper, folded in three layers on a mandrel d=120 mm. The bottom of the tube was made of thick cardboard with a density of 250-500 g/ ^m2 . Gluing was done with low-pressure polyethylene using a heat gun.

The detonation velocity measuring device sensors for the ZBS-10 device were located in the charge through punctures at intervals of 100 ± 2 mm. The first sensor was located at a distance of 50 mm from the bottom of the charge.

A sample of granulated explosive being tested weighing 3000 g ± 10 g was loaded into a tube with a diameter of 120 mm and a height of ~350 mm.

An intermediate detonator formed from ammonite 6ZhV in a plastic cup with a capacity of 400 ml, a height of 72 mm and a "neck" diameter of 95 mm was used as an initiator. The cup was filled with powdered ammonite 6ZhV weighing 400 g, sifted through a 1 mm sieve to remove possible stuck particles. The intermediate detonator was inserted into the tube "upside down" with the wide part towards the GVV charge. An ED (electric contact sensor) was inserted into the bottom of the intermediate detonator through a puncture.

At the first stage of testing, the goal was to evaluate the possibility of developing a composition with a 15% increase in power, solely by replacing the aluminum granules in the most powerful of the approved GVV compositions (granulite A6) with a new type of energy additive.

At this stage of testing, explosive compositions were manufactured based on dense saltpeter according to GOST 2-2013, grade B, produced by JSC NAK Azot.

The compositions presented in Table 1 were prepared as basic compositions: Igdanite (AC/DT) and granulite A6, made from aluminum granules of different dispersed compositions (AC/DT + 6% Al 0-450 μm and AC/DT + 6% Al 0-1000 μm).

Table 1

Sample No. Composition of the GVV Components, % AC DT Alum UK 1 AS/DT - Igdanite 94.5 5.5 2 AS/DT + KED 90 2 6 2 3 AS/DT + Al 0-450 µm 90 4 6 4 AS/DT + Al 0-1000 microns 90 4 6

Considering that the critical diameter of stable detonation of an open charge of explosive compositions based on dense nitrate according to GOST 2-2013 is close to the technically possible in the conditions of the test site (120 mm), in order to be able to control and analyze the development of detonation processes (detonation velocity), the mass of the experimental charges was taken to be 6.0 kg, the number of sensors was 5, the number of measuring bases was 4. The height of the air gap in this series of tests was 150 mm. The composition of the complex energy additive KED used in the experimental studies: Al 0-450 μm / UK = 80% / 20% unless otherwise specified.

After a series of explosions of prototype explosive charges on the test site of the proving ground, there were no remains of undetonated explosives. On all measuring bases, the electric contact detonation sensors were triggered (closed) with the detonation process along the column of charges recorded on the ZBS-10 device. The time and speed of the detonation front were read for each measuring base. The explosive-mechanical effect of the prototype explosive charges was recorded at each experimental explosion by the compression value of the lead crushers.

The results of a series of experimental explosions to determine the detonation velocity in experimental charges based on dense saltpeter according to GOST 2-2013, grade B, series No. 1, are presented below in Table 2, as well as in Figs. 2-3.

Table 2

No. Composition of the GVV Speed on measuring bases Crasher draft D1 D2 D3 D4 m/s m/s m/s m/s h0 h1 Δ, mm % 1 AS/DT "Igdanit" 2353 2326 2278 2146 59.95 45.7 14.25 23.8 2 AS/DT + KED 2309 2865 2793 2994 59.95 36.8 23.15 38.6 3 AS/DT + Al
0-450 microns 2703 2132 2488 2439 59.95 37.6 22.35 37.3 4 AS/DT + Al
0-1000 µm 2564 2237 2232 2119 59.95 38.8 21.15 35.3

Mechanical effect - the efficiency of deformation of lead crushers during the explosion of experimental explosive charges, estimated by the coefficient of explosive efficiency K _VVN based on the magnitude of crusher compression, according to the formula:

To _vv = ,

The coefficient K _VVN for the tested charges, determined by the mechanical compression of the crushers in comparison with the indicator K _VVD , estimated by the detonation velocity of the explosive according to the formula:

K _vvV = D _vv /D _e

presented in Table 3. The results of the explosion of the experimental charge of granulite A6 were taken as the standard-base for comparison.

Table 3

No. Composition of the GVV Δ
D ₁ -D ₂ Δ
_D2 - _D3 Δ
_D3 - _D4 D
average Crasher draft To _BB m/s m/s m/s m/s Δ, mm % To _vvH = To _BBD =
D _vv / D _e 1 AS/DT- Igdanite - 27 - 48 - 132 2275 14.25 23.8 0.79 0.93 2 AS/DT + KED +556 - 72 +201 2740 23.15 38.6 1.02 1,12 3 Reference
AS/DT + Al
0-450 microns -571 +356 -49 2440 22.35 37.3 1.0 1.0 4 AS/DT + Al
0-1000 µm -327 -5 -113 2288 21.15 35.3 0.97 0.94

Based on the results of the conducted testing stage, there are grounds for the following conclusions.

Explosive compositions based on dense nitrate according to GOST 2-2013, grade B in open charges with a diameter of 120 mm detonate in an unstable mode, with a general tendency to fade. An exception is the explosive composition with a complex energy additive KED, the detonation process in which occurs in a mode tending to a stationary one.

Replacement of only the energy additive in the composition of granulite A6 increases the explosive efficiency determined by the settlement of the KVVN crushers by 2%, by the detonation velocity of KVVD by 12%, which does not ensure the achievement of the set goal (15%). The introduction of energy additives in the composition of the AS/DT explosive mixture (comparison base Igdanit) leads to an increase in the explosive efficiency coefficient determined both by the results of detonation velocity measurement data (by average values) and by the value of the crusher settlement.

An increase in the size of the energy additive in the composition of the explosive mixture AS/DT based on dense nitrate according to GOST 2-2013 is accompanied by a decrease in the explosive efficiency coefficient.

Considering that with significant deformations of the lead column (over 30%), the degree of settlement differs from the linear proportionality of the impulse imparted to the anvil during the explosion, in order to increase the accuracy of the measurements, in subsequent experiments the height of the air gap was increased to 200 mm.

Due to the limitation (for organizational reasons) of the permissible mass of the simultaneously detonated GVV charge of 3.0 kg, in order to reduce the length of the acceleration section of the detonation reaching the stationary mode, the diameter of the intermediate detonator made of 6ZhV ammonite in further series of experiments was taken to be close to the diameter of the experimental charge.

In test series No. 2, explosive compositions were manufactured based on porous ammonium nitrate produced by JSC NAK Azot according to TU 20.15.33-073-05761643-2022.

The explosive composition was manufactured as follows.

An AS/DT composition with 2% DT was prepared in the calculated quantity, then the AS/DT composition with 2% DT was mixed with a complex energy additive (CEA), introduced in a quantity that ensured an aluminum content of 6 mass% in the finished GVV.

The composition of the test mixtures is presented below in Table 4.

Table 4

PASS DT Al UK 1 AS/DT granulite RP 94.5 5.5 ~ 2 AS/DT + Al 0-80 90 4 6 3 AS/DT + Al 80-200 90 4 6 4 AS/DT + Al 200-315 90 4 6 5 AS/DT + Al 315-450 90 4 6 6 AS/DT + KED on Al 0-450 90 2 6 2 7 AS/DT + Al 0-450 90 4 6 8 AS/DT + KED 88 2 6 4 9 AS/DT + PAP-2 powder (Al 2-30) 90 4 6 10 AS/DT + KED on Al 0-1000 90 4 6 11 AS/DT KED on coal and Al 0-450 90 2 6 2 (coal)

After a series of explosions of the experimental samples of explosive charges on the test site of the proving ground, there were no remains of undetonated explosives. On all (except experiment No. 10) measuring bases, the electric contact detonation sensors were triggered (closed) with the detonation process along the column of charges recorded on the ZBS-10 device. The time and speed of the detonation front were read for each measuring base. The explosive-mechanical effect of the experimental explosive charges was recorded at each experimental explosion by the compression value of the lead crushers.

The results of experimental explosions to determine the effect of aluminum dispersion and the composition of the energy additive on the detonation velocity in experimental charges based on porous nitrate are presented below in Table 5.

Table 5

No. Composition of the GVV V1 V2 draft m/s m/s h0 h1 Δ, mm % 1 AS/DT granulite RP 2545 2755 59.95 46.6 13.35 22.3 2 AS/DT + Al 0-80 3195 3257 58.75 40.55 18.2 31.0 3 AS/DT + Al 80-200 2994 3021 60.05 43.3 16.75 27.9 4 AS/DT + Al 200-315 2752 3003 59.45 43.5 15.95 26.8 5 AS/DT + Al 315-450 2618 2976 59.9 44.1 15.8 26.4 6 AS/DT + KED on Al 0-450 3367 3509 60 41.2 18.8 31.3 7 AS/DT + Al 0-450 3195 3175 59.25 41.9 17.35 29.3 8 AS/DT + KED 3077 3247 59.4 39.7 19.7 33.2 9 AS/DT + PAP-2 powder ° ° 59.95 40.3 19.65 32.8 10 AS/DT + KED on Al 0-1000 2899 3077 59.85 42.4 17.45 29.2 11 AS/DT KED on coal + Al 0-450 3413 3226 59.75 42.9 16.85 28.2

Data on the change in detonation velocity between measurement bases (Δ D₁-D₂), as well as the value of the average speed by charge (D_Wed), the value of the crusher compression under the action of the explosion impulse (ΔН), the assessment of the relative performance of the explosive by the value of the explosive efficiency coefficient K_vv, produced experimentally, according to the value of direct measurement of the degree of compression of the crusher during the explosion K_vvH=, and indirectly by the detonation velocity KvvD = Dvv/Dэ are given in Table 6.

Table 6

No. Composition of the GVV Δ
D ₁ -D ₂
m/s D
average
m/s Crasher draft To _BB ΔN, mm To _BBD =
Dвв/ _Dэ To _vvH = 1 2 3 4 5 6 7 1 AS/DT granulite RP 210 2650 13.35 1.0 1.0 2 AS/DT + Al 0-80 62 3226 18.2 1.22 1.17 3 AS/DT + Al 80-200 27 3007 16.75 1.13 1,12 4 AS/DT + Al 200-315 251 2877 15.95 1.09 1.09

Continuation of Table 6

1 2 3 4 5 6 7 5 AS/DT + Al 315-450 358 2797 15.8 1.06 1.09 6 AS/DT + KED on Al 0-450 142 3438 18.8 1.30 1.19 7 AS/DT + Al 0-450 -20 3185 17.35 1.20 1.14 8 AS/DT + KED 170 3162 19.7 1.19 1.21 9 AS/DT + PAP-2 powder 19.65 1.21 10 AS/DT + KED on Al 0-1000 178 2988 17.45 1.13 1.14 11 AS/DT KED on coal + Al 0-450 -187 3319 16.85 1.25 1,12

Based on the results of the conducted testing stage, there are grounds for the following conclusions.

All tested compositions detonated in a regime close to steady-state, with positive dynamics in detonation velocity, with the exception of experiment No. 11 on coarsely dispersed coal, in which an insignificant, about 5%, decrease was observed from a relatively high velocity at the first base.

The introduction of any of the tested technological additives into the basic two-component composition (granulite RP) introduces significant changes into the development of the detonation process, expressed in an increase in the detonation velocity and the explosive efficiency coefficient, determined both by the value of the direct measurement of the degree of compression of the crusher, and by an increase in the detonation velocity (the basic value of K _vvn = 1, the composition of granulite RP is taken).

It was found that the determining factor in increasing explosive efficiency is the presence of dispersed aluminum in the composition.

A clear relationship can be traced between the particle size of dispersed aluminum and the increase in the explosive efficiency of the explosive composition.

Fig. 4 shows the results of measurements of the reduction in the height of a lead crusher from the explosive impact of compositions containing aluminum of different dispersion ranges.

The highest explosive efficiency was recorded for a composition based on finely dispersed pyrotechnic powder PAP 2 (size of plate-shaped particles 1-30 µm, with a thickness of 0.5 µm), due to the rapid involvement of small particles with low ignition energy of small particles uniformly distributed throughout the mass of the explosive composition in the detonation process.

It was found that with an increase in particle size, the explosive efficiency in open charges with a diameter of 120 mm decreases, and with particles larger than 315 microns it remains practically unchanged.

It is essential within the framework of the proposed invention to determine the fact that a special difference in the development of the detonation process is observed in compositions with polydisperse aluminum.

As follows from the results of the experiment, the coefficient of explosive efficiency of the composition with UK based on polydisperse aluminum 0-450 μm is higher than that of the composition on PAP2 powder. The introduction of UK into the composition also significantly increases the coefficient of explosive efficiency of compositions with polydisperse (0-450 μm and 0-1000 μm) aluminum.

In addition, the effect of reducing the accumulation of static electricity potentials is observed when introducing a technological additive in the form of crystalline carbon into the composition of the explosive, which leads to an intensification of the relaxation of electrical charges in the aeromixture of the explosive.

This implies the possibility of using this type of mixture to improve the safety of the pneumatic loading process of boreholes and wells.

The next stage of testing involved determining the effect of the KED additive on the detonation characteristics of explosive compositions with polydisperse aluminum. The purpose of the testing was to establish the range of aluminum dispersion that provides an increase in explosive efficiency in the presence of a complex energy additive in the mixture.

Explosive compositions were manufactured based on porous ammonium nitrate produced by JSC NAK Azot according to TU 20.15.33-073-05761643-2022 and ammonite 6 ZhV as a base composition. The KED additive was introduced in an amount ensuring an aluminum content of 6 mass% in the final formulation of the explosive composition.

The composition of the experimental charges for test series No. 3 is presented below in Table 7.

Table 7

No. Composition of the GVV Components PASS DT Al 0-450 Al 0-1000 Carb UK 1-2 Ammonite 6ZhV 3-4 Granulite RP 94.5/5.5 94.5 5.5 - - - - 5-6 AS/DT + KED + Al 0-450 88 2 6 0 2 2 7-8 AS/DT + KED + Al 0-1000 88 2 0 6 2 2

After the explosions of the prototype explosive charges in this series of experiments, there were no remains of undetonated explosives at the test site.

The results of experimental explosions of series No. 3 are presented below in Table 8.

Table 8

No. Type of GVV D ₁
m/s D ₂
m/s D _cf
m/s h ₀ , mm h ₁ , mm Δ, mm To _vvH = To _BBD =
Dвв/ _Dэ 1 Ammonite 6 GV 4274 - 59.95 38.75 21.2 2 Amoonit 6 GV 4292 4425 4358 59.95 37.70 22.25 1.0 1.0 3 AC/DT 94.5/5.5 2268 2137 2202 59.95 52.12 7.83 0.59 0.51 4 AC/DT 94.5/5.5 2222 2000 2111 59.95 52.48 7.47 0.58 0.48 5 AS/DT + KED + Al 0-450 3077 3257 3167 59.95 41,62 18.33 0.91 0.73 6 AS/DT + KED + Al 0-450 2762 3215 2988 59.95 42.72 17.23 0.88 0.69 7 AS/DT + KED + Al 0-1000 2809 3086 2947 59.95 42.06 17.89 0.90 0.68 8 AS/DT + KED + Al 0-1000 2740 - 59.95 43.32 16.63 0.86 -

Based on the results of the conducted testing stage, there are grounds for the following conclusions.

The use of the complex energy additive KED allows to realize the potential increase in the power of the explosive composition from the use of aluminum with particle sizes of normal distribution of crushing products in the polydisperse range up to 0-1000 microns, to a level comparable with the explosive efficiency of Kvvn powdered Ammonite 6ZhV.

The general conclusion based on the results of the conducted series of experiments No. 1-2 is that the introduction of a complex energy additive KED containing polydisperse aluminum and graphite into the explosive composition based on PAS allows for an increase in explosive efficiency of up to 30% in open charges with a diameter of 120 mm in relation to RP granulite.

The introduction of graphite into the composition of mixed explosives based on ammonium nitrate and dispersed aluminum allows for a reduction in the risk of accumulation of dangerous static electricity potentials. In addition, graphite, due to its antifriction properties, allows for a reduction in sensitivity - susceptibility to mechanical loads during the manufacture and use of explosives.

The introduction of dispersed graphite, despite its much lower calorific value, increases the detonation characteristics (detonation velocity, heat and explosion temperature) of mixed explosives with polydisperse aluminum above the indicators when using aluminum powder. It should be concluded that finely dispersed graphite is a starting initiating impulse for the beginning of a chain reaction involving larger aluminum particles in the oxidation process, which provides a synergistic effect manifested in the simultaneous improvement of both the detonation properties of explosives and an increase in safety parameters in the production and use of explosives.

Thus, taking into account the similarity of the development of the detonation process of an explosive composition with the addition of a CED in an open charge and a borehole charge in an array, the proposed invention makes it possible to ensure the creation of a GVV formulation with increased, in relation to a standard GVV, power (by 15%), as well as improved indicators of electrostatic safety of pneumatic loading.

Claims (3)

1. An explosive composition based on granulated ammonium nitrate, containing granulated ammonium nitrate, a petroleum product and a solid combustible component up to 8 wt.%, characterized in that the solid combustible component contains polydisperse aluminum and dispersed graphite, wherein the polydisperse aluminum is made with an aluminum particle size of 70-450 μm, and the components of the explosive composition have the following ratio, wt.%: dispersed graphite 0.5-2.0 polydisperse aluminum 3-6 petroleum product 2-5 granulated ammonium nitrate rest 2. An explosive composition according to paragraph 1, characterized in that the granulated ammonium nitrate is selected from: non-water-resistant, water-resistant, porous, non-porous, or is a mixture of the specified granulated ammonium nitrates, and the petroleum product is diesel fuel, industrial oil, or a mixture thereof.