EP0968985B1 - Cartridged energetic emulsion explosives - Google Patents

Abstract

The encased, dispersed gas phase sensitized, water-in-oil type explosive emulsion comprises ammonium nitrate, sodium nitrate, water, hydrocarbon fuel, emulsifier and aluminum. The encased, dispersed gas phase sensitized, water-in-oil type explosive emulsion comprises (wt.%): 60-70 ammonium nitrate; 8-14 sodium nitrate; 4-7 water; 0.5-5 hydrocarbon fuel; 0.5-5 emulsifier; and 12-18 aluminum; the sum of ammonium nitrate and sodium nitrate being 70-80% and the sum of ammonium nitrate, sodium nitrate, water, hydrocarbon fuel, emulsifier and aluminum being 95-100%.

Description

The present invention is in the field general industrial explosives for civil use.

It is about new explosive emulsions encartouchées particularly adapted for slaughter hard rocks in quarries or on construction sites.

In-line explosive emulsions of the water-in-oil type are well known to those skilled in the art.

• une phase aqueuse discontinue sous forme de gouttelettes d'une solution aqueuse de sels oxydants inorganiques,
• une phase organique continue non miscible à l'eau dans laquelle les gouttelettes précitées sont dispersées,
• un émulsifiant formant une émulsion des gouttelettes aqueuses dans toute la phase organique continue,
• une phase gazeuse discontinue, uniformément dispersée dans l'émulsion, qui permet d'augmenter la sensibilité à l'amorçage de l'émulsion, chaque bulle de gaz dispersée jouant le rôle de point chaud.

They include as constituents:

• a discontinuous aqueous phase in the form of droplets of an aqueous solution of inorganic oxidizing salts,
• a water-immiscible continuous organic phase in which the above-mentioned droplets are dispersed,
• an emulsifier forming an emulsion of the aqueous droplets throughout the continuous organic phase,
• a discontinuous gaseous phase, uniformly dispersed in the emulsion, which makes it possible to increase the sensitivity to the initiation of the emulsion, each bubble of dispersed gas acting as a hot spot.

Compared to the usual dynamites, which contain 25% to 45% nitroglycerin, the emulsions explosives mentioned above have a safety of use and significantly improved manufacturing. In counterpart, they are clearly less powerful and release less explosion energy.

The person skilled in the art has for a long time been search for explosive emulsions of the aforementioned type, presenting both security and sensitivity to priming of explosive emulsions encapsulated known and the power of dynamites, namely a detonation velocity close to 6000 m / s measured in diameter 80 mm confined, and a measured total energy under water above 1100 cal / g approximately.

It is well known to increase the density of explosive to increase their detonation speed. However, in the case of explosive emulsions encartouched sensitized by a gaseous phase scattered, an increase in density implies a a reduction in the volume content in the gas phase and therefore less sensitivity to priming.

It is possible to compensate for this lesser sensitivity by incorporating in the compositions of sensitizing molecules such as nitrate hydrazine and organic nitrates, including amine nitrates such as methylamine nitrate, or well again reaction catalysts such as the copper chloride, or else very oxidizers reagents such as chlorates or perchlorates.

However, the use of such molecules sensitizers, catalysts, and / or oxidizers reagents entails a significant risk of accident pyrotechnic. Indeed, organic nitrates, chlorates and perchlorates are particularly dangerous to handle, hydrazine nitrate is unstable and metal catalysts can react with ammonium nitrate, inorganic oxidizing salt in practice still used in compositions, alone or in admixture with other oxidizing salts.

Patent application EP 598 115 describes for example explosive energy emulsions based on nitrate ammonium containing amine nitrate and / or nitrate hydrazine as a sensitizer.

No. 4,371,408 discloses ammonium nitrate and sodium nitrate explosive emulsions sensitized with an amine nitrate and containing CuCl ₂ as a detonation catalyst.

It is also known to incorporate aluminum in explosive emulsions to increase their energy. However, the increase in the aluminum content is in practice limited by the fact that the performance energy, which is the ratio of the measured energy and the calculated theoretical energy, then decreases strongly.

In addition, it is known that the speed of detonation decreases as the aluminum content increases, due to the decrease in the mass content of the gaseous products in decomposition products.

On the basis of this teaching and these findings, it seemed irreconcilable, to the man of the profession, to obtain emulsions having all the properties and characteristics sought above.

This prejudice has, however, been vanquished.

It has been discovered, particularly unexpectedly, that by combining ammonium nitrate and sodium nitrate, at very good weight contents in the absence of other inorganic salts, nitrate sensitizing molecules organic or hydrazine nitrate and catalysts metal, and by judiciously selecting the nature and the weight content of the other constituents, including the water and aluminum content, we could get explosive emulsions presenting the sensitivity to priming and the safety of use and manufacture of explosive emulsions classics, while presenting the performances of usual dynamites, namely a speed of detonation close to 6000 m / s measured in diameter 80 mm confined and a total energy measured under water greater than 1100 cal / g, possibly exceeding 1200 cal / g, with a energy efficiency above 80%.

The present invention therefore aims to new explosive emulsions encapsulated type water-in-oil sensitized by a gaseous phase dispersed and comprising ammonium nitrate, sodium nitrate, water, a fuel hydrocarbon, an emulsifier and aluminum.

• la teneur pondérale en nitrate d'ammonium est comprise entre 60% et 70%,
• la teneur pondérale en nitrate de sodium est comprise entre 8% et 14%,
• la teneur pondérale en eau est comprise entre 4% et 7%,
• la teneur pondérale en combustible hydrocarboné est comprise entre 0,5% et 5%,
• la teneur pondérale en émulsifiant est comprise entre 0,5% et 5%,
• la teneur pondérale en aluminium est comprise entre 12% et 18%,
• la somme des teneurs pondérales en nitrate d'ammonium et en nitrate de sodium est comprise entre 70% et 80%,
• la somme des teneurs pondérales en nitrate d'ammonium, nitrate de sodium, eau, combustible hydrocarboné, émulsifiant et aluminium est comprise entre 95% et 100%, de préférence entre 98% et 100%, mieux encore entre 99% et 100%.

These new explosive emulsions are characterized in that:

• the weight content of ammonium nitrate is between 60% and 70%,
• the weight content of sodium nitrate is between 8% and 14%,
• the weight content of water is between 4% and 7%,
• the weight content of hydrocarbon fuel is between 0.5% and 5%,
• the weight content of emulsifier is between 0.5% and 5%,
• the weight content of aluminum is between 12% and 18%,
• the sum of the weight contents of ammonium nitrate and of sodium nitrate is between 70% and 80%,
• the sum of the weight contents of ammonium nitrate, sodium nitrate, water, hydrocarbon fuel, emulsifier and aluminum is between 95% and 100%, preferably between 98% and 100%, more preferably between 99% and 100%.

The above-mentioned weight contents are expressed by compared to the sensitized explosive emulsion and must be understood limits included.

The new explosive emulsions mentioned above according to the invention are in particular free of chlorates and perchlorates, for example those of ammonium, metals alkaline or alkaline earth metals, lacking molecules sensitizers of the organic nitrate type, by example of nitrates of alkylamines and nitrates alkanolamines, or nitrates of hydrazines, by example of hydrazine nitrate and nitrate methylhydrazine, free of metal catalysts reaction such as copper chloride.

Moreover, the hydrocarbon fuel can be a mixture of several hydrocarbon fuels and the emulsifier a mixture of several emulsifiers.

The hydrocarbon fuel can be aliphatic, cycloaliphatic, aromatic, saturated or unsaturated. We can be cited for example toluene, xylenes, gasoline, kerosene, fuel oil, paraffins, oils, especially paraffinic oils or naphthenic acids, fatty acids and their derivatives, waxes, and mixtures thereof, namely any mixture of minus two of the above compounds.

Preferably, the hydrocarbon fuel is selected from the group consisting of oils, waxes, paraffins and mixtures thereof.

The emulsifier can be any well-known emulsifier of the skilled person promoting physical stability water-in-oil emulsions by lowering the interfacial tension between the two phases of the emulsion.

The emulsifier is preferably chosen from group consisting of polymeric emulsifiers that simultaneously contain hydrophilic chains and hydrophobic chains, such as polyisobutylene and succinic anhydride, the amines, especially those having from 12 to 24 carbon atoms carbon, esters of fatty acids such as monooleate of sorbitan, sorbitan laurate, palmitate sorbitan and sorbitan stearate, alkylaryl sulfonates, and mixtures thereof.

Aluminum used in the context of this invention is finely divided, preferably powder.

Its particle size is generally between 0.1μm and 250μm, more preferably between 0.5μm and 150μm.

The explosive emulsions according to the invention are sensitized by a dispersed gas phase, according to a method well known to those skilled in the art.

Among the most well-known methods of incorporation from a gaseous phase to explosives in emulsions, can mention the mechanical mixture, the gaseous release in by means of chemical agents, and incorporation a porous material with closed cells, for example microballoons made of glass or plastic, styrene foam beads, or fly ash. We can also associate various methods, for example simultaneously use a chemical agent and microspheres.

According to the present invention, it is preferred to use the gaseous release in situ by means of chemical agents, including the use of nitrites, such as nitrite sodium, which, by reaction with the ammonium ions of the ammonium nitrate, cause in situ formation nitrogen. This reaction can be accelerated by raising of the temperature and / or by a catalyst of urea, thiourea or thiocyanate type.

In a particularly preferred manner, the emulsions explosives according to the invention contain between 13% and 17% by volume of dispersed gas phase, better still between 14% and 16% by volume.

According to a preferred variant of the invention, the sum of the ammonium nitrate and sodium nitrate is between 73% and 77%, better still between 74% and 76%.

According to another preferred variant, the content weight in ammonium nitrate is between 61% and 67%, better still between 62% and 65%.

According to another preferred variant, the content weight in water is between 4.5% and 6.5%, better still between 5% and 6%.

According to another preferred variant, the content weight in aluminum is between 13% and 17%, better still between 13.5% and 16.5%, better still between 14% and 16%.

According to another preferred variant, the content weight of emulsifier is between 1.5% and 4%, better still between 2% and 3.5%.

According to another preferred variant, the content weight of hydrocarbon fuel is between 0.7% and 4%, better still between 0.8% and 3%, better still between 1% and 2%.

Moreover, the density of explosive emulsions according to the invention is preferably between 1.26 and 1.40, better still between 1.28 and 1.37, their speed of detonation measured in diameter 80 mm confined is between 5500 m / s and 6300 m / s, better still between 5750 m / s and 6300 m / s, and their actual total energy, determined under water, is between 1100 cal / g and 1400 cal / g, more preferably between 1200 cal / g and 1400 cal / g.

The explosive emulsions according to the invention can be obtained by analogy with any known process for obtaining explosive emulsions of water-in-oil type sensitized by a dispersed gas phase and comprising ammonium nitrate, sodium nitrate, water, a hydrocarbon fuel, an emulsifier and aluminum.

1) une phase aqueuse par dissolution dans l'eau du nitrate d'ammonium et du nitrate de sodium à une température par exemple comprise entre 100°C et 105°C, dans une cuve munie d'un système de chauffage et d'un système d'agitation. En cas de gazage chimique, on peut optionnellement ajouter à ce stade, dans la phase aqueuse, le catalyseur de réaction précité de type urée, thiourée ou thiocyanate.

2) Une phase grasse, constituée du combustible hydrocarboné et en général de l'émulsifiant, par exemple dans une cuve munie d'un système de chauffage et d'un système d'agitation, par mélange des constituants, à une température par exemple voisine de 95°C.

We can, for example, prepare at first:

1) an aqueous phase by dissolution in water of ammonium nitrate and sodium nitrate at a temperature for example between 100 ° C and 105 ° C, in a tank equipped with a heating system and a stirring system. In the case of chemical gassing, the above-mentioned reaction catalyst of the urea, thiourea or thiocyanate type may optionally be added at this stage in the aqueous phase.

2) A fatty phase, consisting of the hydrocarbon fuel and in general of the emulsifier, for example in a tank equipped with a heating system and an agitation system, by mixing the constituents, at a temperature for example close 95 ° C.

The emulsifier may also not be incorporated into this stage with hydrocarbon fuel.

We then realize, in a second time, the water-in-oil emulsion, either continuously or batchwise.

According to a batch process, after incorporation in a mixer necessary quantities of phase aqueous, fatty phase, and emulsifier if it has not been incorporated into the oily phase, the emulsion can be obtained using a turbine and simultaneously homogenized for example using a clover blade.

According to a continuous process, the two phases, and the emulsifier if it is not incorporated in the phase fat, are pumped by means of metering pumps into feed ducts of an emulsifier.

We then realize, in a third time, the incorporation into the emulsion obtained of the various adjuvants used, namely aluminum, the generator of chemical gas and / or microspheres.

According to the batch process, aluminum, microspheres and / or the chemical gas generator are preferably incorporated into the emulsion by kneading, in the mixer used to produce the emulsion, or in a planetary agitator mixer.

According to the continuous process, the adjuvants are preferably incorporated continuously, for example using endless screw, in a mixer in which also discharges the water-in-oil emulsion from the emulsifier.

The sensitized explosive emulsion thus prepared is then sintered, possibly after a first cooling, manually or automatic, in ducts for example of paper or plastic material, using an installation encartouchage well known to those skilled in the art.

The cartridges obtained are then generally cooled, for example by cold water or air depending on the nature of the sheath, so as to stabilize the final emulsion obtained.

The following nonlimiting examples illustrate the invention and the advantages it provides.

Examples 1 and 2 : Explosive Emulsions According to the Invention

Explosive emulsions having the following weight composition were produced:

Example 1 a) Realization of the aqueous phase

In a tank equipped with a heating system and of an agitation system, dissolve at a temperature between 100 ° C and 105 ° C, 74.3 parts by weight of ammonium nitrate, 13.8 parts by weight of nitrate of sodium and 0.04 parts by weight of thiourea in 6.6 parts by weight of water.

b) Realization of the fatty phase

• 3,7 parties en poids d'émulsifiant constitué d'un mélange 40/60 en poids respectivement de monooléate de sorbitan et d'un polymère constitué de chaínes polyisobutylènes à terminaisons hydrophiles reliées par des fonctions anhydride succinique,
• 1,6 parties en poids . de combustible hydrocarboné constitué d'un mélange 10/35/20/35 en poids respectivement d'une huile minérale naphténique de point éclair supérieur à 100°C, d'une paraffine solide de point de fusion supérieur à 50°C, d'une paraffine liquide de point éclair supérieur à 150°C et d'une cire microcristalline de point de fusion supérieur à 50°C.

In another tank also equipped with a heating system and an agitation system, a mixture of:

• 3.7 parts by weight of emulsifier consisting of a 40/60 by weight mixture of sorbitan monooleate and a polymer consisting of hydrophilic-terminated polyisobutylene chains connected by succinic anhydride functions,
• 1.6 parts by weight. hydrocarbon fuel consisting of a mixture of 10/35/20/35 by weight respectively of a naphthenic mineral oil having a flash point greater than 100 ° C., a solid paraffin having a melting point greater than 50 ° C., a liquid paraffin having a flash point above 150 ° C and a microcrystalline wax having a melting point above 50 ° C.

c) Realization of the emulsion and addition of adjuvants

The aqueous phase (a) and the fatty phase (b) are then introduced into a mixer, then realized the emulsion using a turbine while homogenizing simultaneously mixing with a clover blade. The temperature self-maintains between 105 ° C and 110 ° C in the mixer.

After obtaining a homogeneous emulsion and stable, we add in the mixer, while maintaining stirring and temperature, 17.7 parts by weight powdered aluminum with particle size 0-150μm (diameter median approximately 80μm), then, just before insertion, 0.09 parts by weight of sodium nitrite.

d) Encapsulating the explosive emulsion

Then insert the explosive emulsion obtained in (c), the temperature of which is maintained in plastic sheaths that are then clipped at both ends, to obtain cartridges approximately cylindrical having for example a length of about 320 mm and a diameter of about 80 mm.

The mass of explosive emulsion that we introduce in each sheath is evidently deduced from the volume the desired cartridge, the density of the emulsion explosive that is measured before the encartouchage and the addition of sodium nitrite, and the volume ratio gas phase (about 15%).

When the explosive emulsion contained in the sheath occupies all the volume offered by the cartridge, the desired gas phase volume is achieved and we then stop the formation chemical reaction nitrogen by suddenly lowering the temperature of the emulsion, which is easily achieved by spraying cold water on the cartridges.

Example 2

The procedure is as in Example 1, but with the following differences:

a) Realization of the aqueous phase

74.9 parts by weight of nitrate are used ammonium (instead of 74.3), 13.9 parts by weight of sodium nitrate (instead of 13.8) and 6.7 parts in water weight (instead of 6.6).

b) Realization of the fatty phase

3.2 parts by weight of the emulsifier are used (instead of 3.7) and 1.3 parts by weight of the fuel hydrocarbon (instead of 1.6).

The physical and detonation characteristics of the explosive emulsions obtained according to the usual methods well known to those skilled in the art are as follows:

Claims (10)

1. Cartridged explosive emulsion of water-in-oil type sensitized with a dispersed gaseous phase, comprising ammonium nitrate, sodium nitrate, water, a hydrocarbon fuel, an emulsifier and aluminium, characterized in that:

   the weight content of ammonium nitrate is between 60% and 70%,

   the weight content of sodium nitrate is between 8% and 14%,

   the weight content of water is between 4% and 7%,

   the weight content of hydrocarbon fuel is between 0.5% and 5%,

   the weight content of emulsifier is between 0.5% and 5%,

   the weight content of aluminium is between 12% and 18%,

   the sum of the weight contents of ammonium nitrate and of sodium nitrate is between 70% and 80%,

   the sum of the weight contents of ammonium nitrate, sodium nitrate, water, hydrocarbon fuel, emulsifier and aluminium is between 95% and 100%.
2. Explosive emulsion according to Claim 1, characterized in that the weight content of water is between 5% and 6%.
3. Explosive emulsion according to Claim 1 or 2, characterized in that the weight content of aluminium is between 13.5% and 16.5%.
4. Explosive emulsion according to Claim 1, characterized in that the sum of the weight contents of ammonium nitrate and sodium nitrate is between 73% and 77%.
5. Explosive emulsion according to Claim 1, characterized in that its density is between 1.26 and 1.40.
6. Explosive emulsion according to Claim 1, characterized in that its detonation speed, measured in a confined 80 mm diameter, is between 5500 m/s and 6300 m/s.
7. Explosive emulsion according to Claim 1, characterized in that its real total energy, determined under water, is between 1100 cal/g and 1400 cal/g.
8. Explosive emulsion according to Claim 1, characterized in that its volume content of dispersed gaseous phase is between 13% and 17%.
9. Explosive emulsion according to Claim 1, characterized in that the hydrocarbon fuel is chosen from the group consisting of oils, waxes and paraffins, and mixtures thereof.
10. Explosive emulsion according to Claim 1, characterized in that the emulsifier is chosen from the group consisting of amines, fatty acid esters, alkylaryl sulphonates and polymers simultaneously comprising hydrophilic chains and hydrophobic chains, and mixtures thereof.