NO129143B - - Google Patents

Description

Explosives.

Economical and effective detonator-sensitive explosives are produced by combining appropriate amounts of a non-detonator-sensitive organic liquid containing oxidizing groups with a porous substrate. The preferred liquid is nitromethane or nitromethane diluted with a hydrocarbon. The preferred substrate is a finely divided ionic nitrate powder. The explosives are made explosive sensitive and highly explosive by having a substrate present which disperses the organic liquid while keeping the liquid in intimate contact with dispersed air. The preferred finely divided ionic nitrate substrates used according to the invention are produced by grinding to the desired particle size, preferably below 250 microns.

Background for the invention.

The present invention relates to a two-component, liquid-solid explosive.

For a long time, the explosives industry has searched for a universal explosive and an explosive with considerable explosiveness that can be detonated with a small explosive capsule, e.g. a No. 6 detonator. This type of explosive has been manufactured and sold, but has generally been uneconomical in that the components of the explosive required to make the explosive composition sufficiently sensitive to a No. 6 detonator are expensive. Another disadvantage of such an explosive has been that it is extremely sensitive and must be shipped commercially under explosives regulations. This in turn reduces the economic practicality of such an explosive for all but a few consumers. Most universal explosives and explosives of considerable explosiveness are therefore not of the type that can be detonated with a No. 6 detonator, but they require a transfer charge. The transfer charge in turn causes further expenses in the manufacture and use of the explosive.

One way that explosives manufacturers have so far attempted to circumvent the above problems is to ship an oxidizing component such as ammonium nitrate separately from the fuel. The two components are then mixed at the point of use to form the explosive mixture. However, all these explosives have the disadvantage that they are not sensitive to detonating cap No. 6, but require a transfer explosive. For example, US patent 2,892,377 describes a sealed container of ammonium nitrate. At the point of use, a liquid fuel is injected into the container. The explosive thus formed can be caused to explode by means of a detonating charge. However, the specified explosive cannot be detonated with a No. 6 blasting cap.

Other attempts to produce an explosive detonable with a No. 6 detonator have included the use of a sensitizing fuel such as a nitroalkane. Some of these attempts have been successful, as an explosive mixture that can be detonated with a No. 8 blasting cap can be produced. These compositions also have disadvantages. For example, a considerable amount of nitroalkane is necessary to cause an energy release of such an explosive that is somewhere close to the maximum. (ie that it is oxygen balanced);-The best sensitizing nitroalkane is nitromethane. To get a powerful explosive composed of e.g. nitro<m>ethane and e.g. ammonium nitrate, the mixture must contain considerable unabsorbed liquid. If, when using such a preparation, an explosive capsule, e.g. a No. 6 detonator, is introduced into the mixture below the surface of the liquid level, the composition will not detonate upon explosion of a No. 6 detonator. If, however, the detonating cap of such an explosive is placed above the liquid level, detonation will occur. The undesirable effect of this phenomenon is that in the case of "normal" use of explosives, such care in the placement of a No. 6 blasting cap cannot and is not always taken, which will occasionally lead to non-detonation when exploding No. 6 blasting caps. Such a situation is of course undesirable from a safety point of view, and from the point of view of the manufacturer who wants to produce an explosive that will detonate under any conditions with a No. 6 blasting cap.

It is therefore desirable to have an explosive that is sensitive to a No. 6 blasting cap. Secondly, it is desirable to

have an explosive that can be transported in commerce as a non-explosive. It is also desirable to have a explosive which is a two-component explosive, preferably where one component is a liquid and the other a solid. It is also desirable to have a two-component explosive which is mixed by the final consumer or by the local seller, and which can be easily mixed and combined.

Summary of the invention

The above-mentioned desirable properties of an explosive are fulfilled by the present explosive. The present invention provides an economical, inexpensive, No. 6 detonator sensitive explosive which can be shipped commercially in two components, one liquid and one solid, and which can be easily mixed at the point of consumption. Certain preferred forms of the two-component explosive are self-mixing, and thus require no shaking or physical mixing of the two components.

The explosive according to the invention is sensitive to a No. 6 detonator and contains a solid absorbent component and a liquid, non-detonator-sensitive organic compound and is characterized in that it comprises a solid, porous, absorbent component with a particle size of less than lOOO microns, preferably 5 - 250 micron, and selected from alkali and alkaline earth metal nitrates, ammonium nitrate, alkali and alkaline earth metal perchlorates, ammonium perchlorate, diatomaceous earth and expanded low density silica, and a liquid component mixed with the solid component in an amount whose volume/" less than the volume between the particles of the solid component, and dispersed by capillary action in the solid component, the solid component being insoluble in the liquid component, and the liquid component consisting of a non-explosive sensitive liquid hydrocarbon containing bound nitrogen with a positive valence, and where the capillary action leads to 2 - 90% of the volume of the explosive is one in that being tlie evenly dispersed gaseous component.

The gaseous component can be obtained in the form of air by limiting the amount of liquid used to a volume smaller than the interstitial volume of the solid component. The solid component can be either free flowing or sintered. A smaller amount of a hydrocarbon gel can be mixed with the liquid component if desired. Mixing of the solid, liquid and gaseous components can be carried out without external mechanical stirring by capillary action in the finely divided solid substance, forming a homogeneous mixture of solid, liquid and gaseous components. The mixture will not separate or layer and does not require gelling agents to maintain homogeneity.

The liquid component is preferably a nitroaliphatic hydrocarbon, a nitroaromatic hydrocarbon, an aliphatic nitrate, an N-nitrohydrocarbon or a mixture thereof.

Description of preferred embodiments

The explosives according to the invention therefore include

a liquid component that can be conveniently stored or transported in a bottle, jug or other suitable container to the point of use. The liquid component of the explosive according to the invention is a non-explosive sensitive hydrocarbon material which can be shipped freely in ordinary trade, and which is activated at the point of use by the porous solid component of the explosive according to the invention.

The liquid component of the explosive according to the invention is characterized by a non-explosive cap sensitivity. liquid hydrocarbon material containing bound nitrogen in a positive valence form [see e.g. Lange: Handbook of Chemistry, 10th ed.

(1961), page 56. Nitrogen has e.g. a negative valence in ammonia (NH^)> but a valence of +1 in nitroso compounds,

of +3 in nitrogen compounds and of +5 in nitrate compounds. Typical compounds of this group of materials are nitro and nitrated hydrocarbons. Examples of materials that can be used within the scope of the invention include nitroaliphatic hydrocarbons, nitroaromatic hydrocarbons, aliphatic nitrates, N-nitrohydrocarbons and mixtures thereof. Preferred liquid components include the nitroalkane compounds containing 3 or fewer carbon atoms and mixtures of the lower dinitroaromatic compounds. Nitromethane and the dinitrotoluene oils are preferably used. The liquid component may be present in amounts from 6% to 60% by weight of the explosive composition. It is most preferred that the liquid component constitutes 12% to 35% by weight of the total explosive.

The explosives according to the invention include another, porous, solid component which can be conveniently stored and shipped in flexible or fixed fiber containers or other suitable containers to the place of use. The solid component of the explosive according to the invention preferably comprises a non-explosive cap-like inert or oxidizing material, which can be freely shipped in ordinary trade. The primary function of the solid component is to provide a porous base or substrate which will evenly disperse the liquid component by capillary action, thereby automatically providing an intimate mixture of the liquid component and air. An "other function of providing additional" energy by reaction of an oxidizing group with an excess of the fuel portion of the liquid component can be provided by an oxidizing solid component. If an oxidizing material contains potentially gas-forming elements in addition to the elements of the oxidizing group, a third function of the solid component is to provide expandable gas capable of doing useful work. Solid components which are applicable within the scope of the invention are alkali and alkaline earth metal nitrates, ammonium nitrate, alkali and alkaline earth metal perchlorates and ammonium perchlorate. Preferred solid components include potassium, sodium and ammonium perchlorates, diatomaceous earth and expanded silica, with ammonium nitrate, sodium nitrate and potassium nitrate being the most preferred. -

In the form in which the solid component compositions are usually kept as commercial products, they are not desirable for use in the explosive composition according to the invention. In order to obtain a suitable substrate, it is first advisable to comminute the solid material to a particle size below 1000 microns, preferably below $00 microns, and preferably in the range from 5 to 250 microns.

Furthermore, it is desirable to treat the solid component to bring the volume density of the solid material to a maximum value under normal storage conditions. It is preferred that the space volume is at least 10 percent by volume greater than the amount of liquid component to be mixed with it. Ideally, the remaining interspace volume should be at least 10$ greater than the volume of the amount of liquid component corresponding to an oxygen-balanced final explosive mixture. Two methods can be used to produce a substrate of the desired low bulk density. In the first method, the finely divided solid, in a loose, fluffy state, is treated with water, from 0.2% to 5% by weight, preferably approx. 1%. Alternatively, moist air with a corresponding water content can be used. The moist solid is then dried at ambient or higher temperature to produce weakly sintered agglomerates that resist settling and compaction. In the second method, the milled solid can be sifted through different sieves to obtain individual fractions of uniform particle size and low volumetric weight. Carefully regulated measuring methods can eliminate the necessity of these secondary treatments in many cases, but such treatments are useful and generally undesirable in the manufacture of two-component explosive compositions in which long diffusion paths for the liquid are needed and/or in which very rapid mixing is required.

Smaller amounts of a fuel component can also be added to the liquid component under certain conditions. Thus, if the porous solid component is an oxidizing material and it is desired to obtain a final explosive mixture which is substantially oxygen balanced, it may occur that the amount of liquid component required exceeds the interstitial volume of the solid component resulting in a mixture which is not explosive-capable. Under such conditions, a smaller amount of a fuel component is mixed with a higher fuel value per unit volume than the nitrogen-containing liquid thus. This will give a final liquid component which can be added to the solid component in a smaller volume amount, and give a final explosive mixture which is oxygen balanced and which contains the necessary air distributed in spaces. In the case of the aromatic dinitro compositions, a small amount of a fuel component may be added to the liquid component to lower the pour point or freezing point to a more convenient range. Fuels that can be used to increase the volumetric fuel value of the liquid component must meet three basic requirements: Firstly, they must be chemically compatible with the ...liquid component, secondly, they must be miscible with the liquid component in the desired ratio , and thirdly must

they have a considerably higher volumetric fuel value than the liquid component. Many inexpensive commercially available compounds and mixtures meet these requirements. Examples of such compounds and mixtures are: aromatic hydrocarbons (benzene, toluene, xylene, aromatic naphtha), lower aliphatic alcohols (methanol, ethanol, isopropanol), lower ethers, lower ketones, lower aldehydes, lower organic acids, lower esters and small amounts of aliphatic hydrocarbons of the^gasoline fraction.

Since an exact theory cannot be put forward, it is assumed that the sensitization of potentially detonable, but non-explosive-caps-compatible liquids with porous solids takes place according to the following mechanism. The liquid component is absorbed and distributed in the solid matrix by capillary action, forming an intimate mixture in which the solid particles are essentially surrounded by liquid films which in turn are limited by very small layers of gas, usually air. When a warhead is detonated in the mixture, it creates intense pressure that compresses the very small gas bubbles adiabatically, creating extremely high temperatures at the liquid interface and causing the liquid to explode by heat. The locally exploding liquid in turn compresses several gas bubbles and thus transmits the explosion through the mixture. If the solid particles contain oxidizing groups, these in turn react with the hot fuel-rich mixture from the liquid and thus add energy to the explosion as well as gaseous products in most cases. Although it is believed that this is the mechanism by which the two-component explosive compositions work, it is not intended that the invention be limited to this theory.

The gaseous component according to the invention can be present in amounts from 2% to 90% by volume of the total explosive composition. However, it is preferred that the gaseous component is present in the range from 5% to 50% by volume.

Examples

The following examples are given to further enable a person skilled in the art to carry out the present invention. In addition, they indicate preferred ways of carrying out the foregoing. All percentages are given by weight.

Example 1

Sodium nitrate crystals are ground by hand in a mortar to obtain a fine powder with an average particle size of less than

100 microns. A 20 g sample of this powder is lightly tamped into an aluminum tube (6K mm long x 22 mm inner diameter x 25 mm outer diameter) fixed at one end to the center of a square piece of cold-rolled steel (76 mm x 76 mm x 16 mm) . 10 g of nitromethane. is added to the contents of the rudder without stirring. The metal trial device was placed symmetrically, on a vertical 76 mm long piece of 50 Km rudder that rested on a large steel plate approx. 6.^ mm thick. A No. 6 detonator

was placed in the top center of the aluminum rib in intimate contact with its contents and detonated. ■ The charge exploded, forming a dent in the steel plate 2.01 mm deep in the centre.

Example II

The procedure in Example I was repeated using

7 g of diatomaceous earth instead of the sodium nitrate. Upon detonation, a loud bang was heard and the steel plate was dented 7?*+ mm. Example III The procedure in Example I was repeated using 20 g of potassium nitrate instead of the sodium nitrate. Upon detonation, a loud bang was heard and the steel plate was dented 2.08 mm. Example IV The procedure in Example I was repeated except that the average particle size of the ammonium nitrate was greater than 100 microns and less than 250 microns. Essentially the same result was obtained. Example V The procedure in Example I was repeated using 20 g of ammonium nitrate instead of the sodium nitrate. Upon detonation, a loud bang was heard, and the plate was dented 2.03 mm" ;Example VI ;A mixture of 28 g of diatomaceous earth and 20 g of dinitrotoluene oil with a melting point of 35°C was prepared by heating the components to 75°C. The mixture was wrapped in aluminum foil and placed on a 3.2 mm steel plate on the soil. When the mixture was initiated with a No. 6 blasting cap, a loud bang was heard and the steel plate was considerably bent. Example VII A mixture of 120 g of dinitrotoluene oil with a boiling point of 26°C and 10 g of high-boiling petroleum naphtha was prepared, whereby a liquid composition was obtained at room temperature. This mixture was added to 1000 g of finely divided ammonium nitrate (average particle size below 100 microns). The final mixture was placed in a plastic bag on a limestone stone approx. 0.76 m^ of stbrrelse. The mixture was detonated with a No. 6 explosive cap which produced a loud bang and shattered the stone. ;Example VIII ;A mixture of 80 g of xylene and 185 g of nitromethane was prepared ;and added to 1000 g of finely divided ammonium nitrate (average particle size below 100 microns). The final mixture was placed in a plastic bag on a limestone rock approx. 1.5 of steel barrel, and detonated with a No. 6 blasting cap. A loud bang was heard and the stone was shattered. ;Example IX ;A large batch of ammonium nitrate powder was produced with a factory hammer mill with a high production capacity. A sample of 150 g of material with an average particle size below 100 microns was firmly tamped into a foil laminate pouch and sufficient nitromethane (75 g) was added to the pouch to produce an oxygen balanced mixture. The final mixture appeared very wet with free liquid visible. The foil pouch was placed on a steel plate (76 mm x 76 mm x 16 mm) and detonated with a No. 6 detonator. A faint bang is heard. The steel plate was undamaged. ;Example X ;The method in Example IX was repeated using a mixture of 52.2 g of nitromethane and 3.0 g of xylene instead of pure nitromethane to form another oxygen-balanced mixture with a smaller liquid volume with a correspondingly larger gas volume. When detonating with a No. 6 blasting cap, a loud bang was heard, because the steel plate was severely bent and dented. ;Example XI ;The procedure in Example IX was repeated using 150 g of the factory milled ammonium nitrate identical to that in Example IX, but the material was mixed with 1% by weight of water, set aside for 10 minutes, and stirred at room temperature for 2 hours on board because it was stamped in the wallet. This method reduced the final volume density of the ammonium nitrate.' Upon detonation, a loud bang was heard and the steel plate was severely bent and dented. ;Example XII ;A mixture of 29 g of nitromethane and 1.7 g of xylene was sealed in a small pouch made of polyethylene-aluminum foil- (0.0089 mm)-polyethylene-polypropylene laminate having a total thickness of less than 0.1 mm. The sealed pouch was placed in an oven at 75°C for one week. On weighing to the nearest l/lOO g, it turned out that the sample had not lost any measurable weight. Example XIII 166 g of finely ground ammonium nitrate was sealed in a pouch identical to that described in Example XII. The scrotum was immersed in several cm of water for a week. The bag was opened and a mixture of 57.7 g of nitromethane and 3.32 g of xylene was added. The mixture was placed on a steel plate (76 mm x 76 mm x 16 mm) and detonated with a No. 6 detonator. A loud bang was heard, and the steel plate was severely dented and bent. ;Example XIV ;A mixture of 83 g of finely ground ammonium nitrate with an average particle size below 100 microns and 30 g of nitromethane in a foil laminate cylinder of approx. 28 mm diameter and 152 mm long was submerged halfway into an open container of 1500 g of unsensitized nitromethane. A No. 6 blasting cap was inserted into the top of the cylinder approx. 76 mm above the surface of the nitromethane. Upon detonation, a very loud bang was heard, and extensive ground damage occurred, which showed that the nitromethane had detonated. Example XV A mixture of 83 Q of finely ground ammonium nitrate with an average particle size below 100 microns and 35 g of nitromethane in an aluminum foil laminate bag was immersed in 2000 g of prilled ammonium nitrate/purifying oil (AN/FO) in a plastic bag. This bag was placed on a sl: '1 of approx. 0.76 m volume. A No. 6 detonating capsule was placed in folit>:i. in the night bag. Upon detonation, a very loud bang was heard, and the seat was shattered, which showed that AN/FO detonated. ;T <1> high explosive devices have been adapted for use with uncomponent explosives.. These devices include, but are not limited to: lined and unlined shaped charges, boulder crushing charges, transmitters, secondary explosive charges, seismic charges, fuses, bombs, grenades, mines and borehole charges. A new application of the two-component explosive is in devices containing three explosive charges where the second charge is a detonable non-explosive explosive sensitive to nitromethane or an ammonium nitrate cleaning oil mixture (AN/FO). The primary or transferrladniny «r the two-component explosive. In the case of nitromethane, the liquid in the other charge can be used as a liquid component for the two-component explosive.

Claims (10)

1. Explosive substance sensitive to a No. 6 detonator, containing a solid absorbent component and a liquid, non-detonator-sensitive organic compound, characterized in that it comprises a solid, porous, absorbent component with a particle size of less than 1000 microns, preferably 5 - 250 micron, and selected from alkali and alkaline earth metal nitrates, ammonium nitrate, alkali and alkaline earth metal perchlorates, ammonium perchlorate, diatomaceous earth and expanded low density silica, and a liquid component mixed with the solid component in an amount whose volume is less than the volume between the particles of the solid component, and dispersed by capillary action in the solid component, the solid component being insoluble in the liquid component, <p>g the liquid component consists of a non-explosive liquid hydrocarbon containing bound nitrogen with a positive valence, and where the capillary action leads to 2 - 90$ of the volume of the explosive being an essentially uniform dispe rgered gaseous component. 2. Explosive according to claim 1, characterized in that the liquid component is selected from among nitroaliphatic hydrocarbons, nitroaromatic hydrocarbons, aliphatic nitrates, N-nitrohydrocarbons and mixtures thereof. 3. Explosives according to claim 1 or 2, characterized, i.e. that the liquid component also contains a smaller amount of a hydrocarbon fuel mixed with the liquid component. •+. Explosives according to requirements 1 - 3) characterized in that the gaseous component makes up at least 5% by volume of the explosive. 5. Explosives according to requirement 1 - characterized in that the liquid component makes up 6 - 60% by weight of the explosive. 6. Explosives according to requirements 1-5) characterized in that the liquid component makes up 12 - 35% by weight of the explosive. 7. Explosive according to claims 3-6, characterized in that the hydrocarbon fuel is an aromatic hydrocarbon. 8. Explosives according to requirements 1-7, characterized in that the gaseous component, preferably air, is present in an amount of 5 - 50 percent by volume of the entire explosive. 9. Explosives according to requirements 1-8, characterized in that the volume weight of the solid component is below 1.<*>+ g/cm 3 , preferably below 1.0 g/cm-o 3 . 10. Explosive according to claims 1-9, preferably in the form of a charge, characterized in that it further comprises a transfer charge placed next to a secondary, non-explosive explosive, which preferably comprises a mixture of ammonium nitrate and. fuel oil.