FI118646B - Phlegmatized explosive - Google Patents

Abstract

An explosive in semi-plastic, paste or slurry form, comprising at least one high explosive in molecular form and comprising or including at least one pulverulent component, which explosive further comprises a flegmatizing agent, including solid particles of a material more soft or deformable than the particles of said pulverulent component.

Description

1118646

The present invention relates to an explosive composition in semi-plastic, pasty or slurry form, containing more than 10% by weight of at least one liquid nitric acid ester compound gelled with nitrocellulose, at least one crystalline powdery component comprising an oxidizing salt, and retarder for.

One of the basic problems in the design of explosive compositions is to find an acceptable balance between safety and the non-deliberate ignition of an explosive during its manufacture, transport and handling, prior to detonation, and ignition and detonation when detonated. Actions that affect one's own 15 characteristics generally also affect another characteristic. Intentional initiation (ignition) is normally accomplished by a shock produced by a detonator or ignition charge, and it is desirable that the explosive be more sensitive to these effects than, for example, the energy produced by friction, heat or electrical discharge. In addition, it is desirable that the sensitivity can be changed • · ·. £: fairly easily, since explosives used in large · * · volumes or in large boreholes will still • • • have less sensitivity to ignition and explosion. 25 as explosives used in smaller quantities or in smaller holes.

Many current explosives, such as those in the form of emulsions or slurries, based primarily on in-depth blends of fuels and oxidants rather than self-explosive compounds, provide numerous parameters for affecting sensitivity: ** * ·, Including the degree of fineness, the interfacial interface and the density of the composition. Sensitivity during manufacture is rarely a problem as flammable explosives are obtained during the final stages of manufacture.

m · * * Φ • ♦ • * 2 118646

In contrast, the sensitivity of classical explosives based on brilliant molecular explosives is not easy to influence since this property is largely inherent to the molecular explosive itself. Safety and sensitivity aspects are also sought to be taken into account in larger parts of the manufacturing process in the case of molecular explosives.

Molecular, highly explosive, explosives are usually either in solid crystalline form (e.g. TNT) or in liquid form (e.g. liquid nitric acid esters such as nitroglycerols and nitroglycols, hereinafter generally referred to as "NG"). From a rheological point of view, commercial explosives are preferably in particulate, paste or slurry form rather than solid or liquid form. Crystalline explosives can be mixed with one or more liquid ingredients to form a paste, and NG is usually gelled and mixed with large amounts of solid ingredients such as oxidizing salts. The presence of solid powdery constituents in the formable explosive affects its sensitivity and, in particular, its response to friction.

····; ; * · The presence of na ja 25 yppi 25 25 · · 25 25 25 25 25 issä issä 25 issä 25 25 issä 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 tekee tekee tekee tekee tekee tekee tekee tekee tekee tekee tekee tekee. Tekee tekee tekee tekee tekee · · · · · · · ·. sensitivity is often particularly difficult.

Solid crystalline explosives have been made • · · * more flammable (henceforth referred to as "retarded") by the addition of particles to or between the particle interfaces. Examples of suitable additives for this purpose are molten wax and inert compounds. The additions tend to prevent the transfer of mass and heat between the particles, which not only reduces the sensitivity but also reduces the flammability and overall reaction rate. NG blasting agent: · *: Usually, a retardant is added and dissolved in a gel which is obtained between the NG component and the gelling agent. The requirement that the retardant dissolve greatly limits the number of possible compounds. First, the stability of NG gel is limited and tends to become more unstable when additional ingredients are added. Chemical similarity is required for the retardant and the gel components, and various nitrated compounds are commonly used, some of which, such as mono- and dinitrotoluene, are hazardous to health and in many cases incompatible with conventional packaging materials due to their volatility or plasticizing action. With regard to crystalline explosives, additives act not only to reduce harmful sensitivity but also to reduce flammability and reactivity in general.

One main object of the present invention is to provide a retarded explosive without the above-mentioned drawbacks. One more specific object is to provide an explosive containing a retardant which is generally useful in compositions containing powdered ingredients. Another purpose is to provide usable * · | t; ί si a slow-motion explosive whose sensitivity is easy to change.

V In addition, the goal is to provide a retarded blast ···· •; * · residue with good flammability and reactivity.

* ··: 25 One goal is still to offer the use of slow motion • ··! explosive with reduced friction sensitivity. A further purpose is to provide a cheap retarded explosive • · · * de. One further goal is to provide an explosive retarded with non-hazardous ingredients.

These objectives are achieved by the present invention.

; ***. The present invention relates to an explosive composition in semi-plastic, paste or slurry form, containing more than 10% by weight of at least one • m * ··. * 35 liquid nitric acid ester compound gelled. nitrocellulose, at least one crystalline powdery 4118646 component comprising an oxidizing salt, and a retarding agent. The composition is characterized in that the retardant comprises 0.5 to 10% by volume of the composition of solid particles which are softer or more readily deformable than the particles of said crystalline powder component, and that the retardant particles have a weight average particle size greater than crystalline powder. weight average particle size.

According to the invention, an explosive similar to the one initially mentioned contains a retardant comprising solid particles which are softer or easier to deform (deformable) than the particles of said powdered ingredient.

The particles, which are softer than the powdery ingredients present in the explosive containing the molecular explosive, act to achieve some of the set goals. Without being bound by any theory, it is believed that the point presence of particles in the explosive composition, in contrast to the molten or distributed additive, contributes to good overall reactivity and flammability in the composition by avoiding the presence of either a solid or liquid molten ·; basic features; * · change of mouth. Unchanged reactivity provides • · ·:. *. 25 stable flammability and explosive properties over a wide range of temperatures. However, when exposed to mechanical stress, softer particles tend to • · · * first pass and thus effectively dampen the effects of such stress and are particularly effective in preventing local • · ... * local release of energy ·· * ... Sea buckthorn, which is subject to particulate mass under load. otherwise it will inevitably occur. In addition, it is believed that · «· the plasticity (deformability) of the particles is a particularly effective means of attenuating shear and frictional stresses,« Φ · * ... · · · · · · 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 rea. ; · Legal strain. Because the retardant effect of the particles is believed to be mechanical rather than chemical, the same principles can be applied to many different explosives that meet these basic requirements. The bonding effect can be varied by the number of particles added easily. In addition, the solid nature of the particles removes previous problems caused by volatile or migratory additives. The additive is well compatible with explosives containing liquid phase. Since no solubility is required for the substance in question, the 10 potential fluid explosive component remains intact and, in particular, the rheological properties of explosives based on NG gel are improved compared to known types. Furthermore, the same property makes a large number of substances suitable for the purposes of the present invention. It is easy to find substances which are compatible with both hydrophilic and lipophilic compositions, as well as substances which are inert, harmless and odorless. Freedom of choice allows the choice of a substance that offers secondary benefits, such as improved water resistance and reduced formation of salt cans with hydrophobic additives.

Other objects and advantages of the invention will become apparent from the following detailed description.

•; * · The principles of the invention can be applied before • ·:. *. 25 everything from semi-plastic, pasty or slurry ··· · explosives, ie formable explosives, capable of adapting to various shapes during loading and more, rather than rigid solid or pressed explosives.

Preferably, the invention is applicable to explosives containing a liquid or gel phase, and preferably a paste. compositions having a certain plasticity.

· * · The explosive may be in the form of bulk material for direct drilling, though certain additional benefits may be achieved by the use of bulk explosives, such as ··· j V in tube or cartridge and 6 118646 any size. The invention can be applied to explosives which require an ignition or auxiliary charge for initiation (ignition), but the invention is particularly significant with regard to more sensitive explosives which can be fired at a number of 8 or less. Of particular importance is the application of the invention to explosives, which are otherwise extremely sensitive to ignition by mechanical stress, in particular friction.

While there may be some general ten flavors of the invention in explosive composition identifiers, it is preferred to apply the invention to explosives containing a molecular explosive, which term includes both true such as co-crystallized fuel and oxygen components and solutions of components all characterized by the absence of any macroscopic interface between the critical components. Preferably, the explosive contains a true molecular explosive, such as a high-explosive. Such an explosive may be in solid or liquid form. Solid Explosives • •• f. can be amorphous, such as thawed and rapidly cooled ···:, ·. 25 but are usually and · · · ** V preferably in crystalline form. Typical but not limited examples of these are RDX, HMX, HNS, PETN, and especially TNT. Liquid explosives may be solutions, preferably between some pure oxidant and fuel, or preferably liquid real molecular explosives, such as nitro-paraffins (ex. ** ·, e.g., nitromethane, nitroethane). , nitropropane, tetranitromethane, etc.) but preferably NGs. List • *. also includes intra- and inter-group combinations and · ... · 35 mixtures. In order to take full advantage of the advantages provided by this invention, the amount of molecular explosive in the explosive decomposition should be greater than 10% by weight and preferably greater than 12% by weight.

Preferred explosives for use in the present invention are NGs, i. liquid nitric acid esters and in particular glycerol nitrinitrate and especially ethylene glycol dinitrate. Usually, these liquid true molecular explosives are gelled or thickened with a gelling agent, which may be, for example, nitrated starch or preferably nitrocellulose. In addition to providing a liquid other than liquid, the compositions additionally contain significant amounts of a solid which may be an inert filler such as diatomaceous earth, but is preferably an oxidizing salt, further explained below, optionally combined with any solid solid fuel such as flour, wood flour or coal. , such as partially nitrated paraffins or aromatic hydrocarbons. For certain purposes, the composition may additionally contain small amounts of other additives, such as flame-cooling salts or dye-20 or buffering agents. Depending mainly on the ratio of NG gels to solids, the product may be obtained orally; in a powdered form with up to about 15% by weight of NG gels, in a semi-plastic form with about 13% to about 20% and approximately ··· j. In plastic form, in amounts of about 15 to 60% by weight, preferably 18 to 30% by weight. Preferably, the present invention is used in connection with the described semi-plastic and plastic or paste-like types, and in particular with the conventional NG-type, which contains as its main solid an oxidizing salt and sufficient

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amount of gelled NG to achieve the desired rheology ··· _ • ♦ SI · • · for explosives which are not NG * or mixtures of other explosives with * · .. * 35 or ingredients, liquid present, fluid ·· ·: *., or total gel should be sufficient to achieve the desired 118646 s of semi-plastic, paste or pellet rheology. In such cases, the same numerical values (percent by volume) as those given above for the 5 NGs may be applied to the total fluid volume to achieve the corresponding rheological properties.

The explosive of this invention must contain at least one powdery component other than a retardant. Depending on the basic nature of the ra-10 refrigerant used, the powdered ingredient may be very different. It may be an inert filler such as clay, an absorbent filler such as diatomaceous earth, a porous density-reducing filler such as mineral or plastic microspheres or small polystyrene foam balls. Preferred ingredients are the aforementioned solid explosives and especially oxidizing salts. Conventional oxidizing salts include inorganic nitrates and possibly also perchlorates. In addition to alkali or alkaline earth metal nitrates and perchlorates, ammonium nitrate is generally preferred. The powdery constituent is preferably crystalline in nature rather than amorphous.

ij1: The explosive may contain a mixture of several of these types of powdery · 1 · or a mixture with the oral · 1 ·. .1. higher or lower amounts of other such ingredients. Co- ···:. ·. The conic solids content of the explosive may be quite high, for example more than 20% by volume, preferably more than 40% by volume, and preferably more than 60% by volume. Plastic explosives may contain sufficient solids to achieve the desired rheology. In the context of this invention, "powdery ingredient" means the majority (by volume) of solids in the composition, or such *. · 1 ·. a harder solid component of the mixture consisting of several «φ · significant fractions.

• · • The retardant contains particles (and preferably · ·· * ...: 35 consists of particles) which are softer or easier • 1 · V deformable than the particles of the powdered substance. The particle condition requires the substance to remain solid and retain its maximum circuit size at all intended operating temperatures until initiation. Preferably, the substance has a melting or softening temperature of more than 40 ° C and more preferably above 60 ° C. It also requires that the substance is chemically stable or inert in the composition, has a sufficiently low swellability, and does not substantially alter its solubility in the explosive during its intended life.

The softness or plasticity (deformability) of the particles can be achieved in many ways. Soft crystalline materials such as talc or graphite may be used. The crystalline materials may also be soft due to poor agglomeration of the harder particles or due to the thin walls in the porous materials. Preferably, the material can be deformed to retain its phase structure, since much of it is an amorphous or semi-fluid phase which provides very clear lubricating properties. The phase may contain non-liquid-like constituents, for example microcrystals, but is preferably substantially homogeneous. The phase may contain inorganic substances such as jellies or water glasses, particularly when hydrophilic materials are desired. ·, Le and, but generally organic materials are preferred. Va- • m * •, ·. 25 castles depends on, for example. • · · ** V of explosive compositions. Hydrophilic substances such as carbohydrates or polymers containing hydrophilic substituents may generally be used in lipophilic or oil-containing explosives. Generic: * “30 In hydrophilic explosive compositions such as NG ···:., Ϊ explosives, the substance may prefer to be hydrophobic. Oh, ···. oligomers or polymers may be used, optionally in combination with plasticizers. Can be used alone- *. • * · * ... · 35 hydrocarbons, particularly pure, saturated. Preferred agents are substances commonly referred to as "waxes", such as acid waxes, ester waxes, oxazoline waxes, and in particular hydrocarbon waxes such as paraffin waxes or petroleum waxes. Although there is no perfect corre-5 between the softness of the substance and its softening or melting heat state, in general it seems that melting! the softening temperature should be below 250 ° C, preferably below 200 ° C and preferably below 150 ° C.

The condition for softness requires that if the mixture of powdered ingredient and solid particles is subjected to compression, shear or other mechanical stress Dec. 10, the particles will give, deform, or move before the particles of the powdered component are deformed. One common ingredient in explosives is ammonium nitrate, and when used as reference 15, it is preferable that the particles are clearly softer or more readily deformable than the crystals of the ammonium nitrate salt. Specifically, it is preferred that the particles have a Moh hardness of less than 3, preferably less than 2, and most preferably less than 1 at the intended temperature. The lower limit is defined by the requirement for the stability properties of the particles under operating conditions as described.

:: *: For best performance, it is advantageous to · · · · · · · · · · ·; Is significantly higher than the mean mass of the particles. 25% in total powdery matter or solids ·· * * generally, whichever is greater, although soft "II particles such as wood flour or flour may be disregarded in calculating the average. Said average is preferably 2 times higher and more preferably 5 times ** i ** 30. To be precise, said mean particle size may be from 0.01 to 5 mm, and preferably from 0.1 to 1 mm.

The amount of retardant to be included in the explosive depends on the desired degree of reduction in sensitivity. The additive · 'is surprisingly effective and only needs a limited amount of · · * ... * 35. The amounts must be clearly less than the other solids in the composition (· Volume Base 11 118646), for example less than 1/5 and preferably less than 1/10 of the amount mentioned. Preferably, the amount (by volume) is also significantly less than the amount of the powdered ingredient, for example less than 1/5 and preferably less than 1/10 of the said amount. The upper limit is mainly determined by the decreasing contribution to the decrease in sensitivity, the dilution effects on the explosive and, in the case of flammable additives, the incremental firing value. Specifically, a suitable range is from 0.1 to 15% by volume and preferably from 0.5 to 10% by volume.

Other retardants may be used in combination with the agent of the present invention to effect, for example, part of the sensitivity in a conventional manner. Any known retardant, such as melted or liquid ingredients, which can be dispensed into the composition may be used. Liquid ingredients are generally preferred. Suitable hydrophobic liquid compositions include Oils and especially paraffin oil which increases water resistance and favorable viscosity properties. One suitable hydrophilic additive is water. The amount of such additives should be kept low, preferably less than 5% by weight, and preferably less than 2% by weight. As a general rule, the amount of such additives • «M 'should be kept below the amount of particulate material according to the invention.

The explosives of this invention may be selected. • using similar methods to similar explosives without slow motion. The substance in question may be added in a simple mixing step, preferably with the other solid ingredients, in order to utilize the slowing effect ··· • m '··· ”for optimum use; ***; during mystification. Only high mechanical stress at high temperatures can inactivate a substance which is rarely found in the manufacture of explosives.

! · · ·! 35 · «· • · · • • 12 118646

eXAMPLES

In the following examples, the same general manufacturing method was used. The stream containing pure nitroglycol separated from the aqueous emulsion after the nitration step is weighed and delivered to a mixing vessel equipped with screw mixing means. A weighed amount of nitrocellulose is added to the vessel along with any wetting and dye additives, and dinitrotoluene, when present (Example 1), heated to slightly above its melting point. The mixture is stirred for a couple of minutes until a jelly is formed. If paraffin oil is to be present, then it is added, followed by solid ingredients, wood flour, flour, ammonium nitrate salt and a paraffin wax component. Simultaneously with the addition of salt, additional water is possibly injected into the mixture through a nozzle. The mixture is kneaded for about 3-4 minutes or until a homogeneous mixture is obtained.

Sensitivity to impact by falling weight 20 is measured by placing an explosive sample, about 2 mm in diameter and about 1 mm thick, on an abrasive mat in a cylindrical cavity within a steel core substantially larger than the sample by placing a slug inside the cavity. ·. drum steel piston in a position where it is • • t ···:. 25 samples from the upper surface. Subsequently, a 1 kg · · · “V drop at different heights is dropped and allowed to strike the plunger and push the latter into the bottom of the cavity, whereupon the sample is compressed. The minimum height required for the sample to ignite is determined.

··· *** 3 0 Example 1 * * ·

First composition, reference composition, ready. * · *. was performed using dinitrotoluene, a conventional ·· retardation medium. The composition contained the following ingredients, the pulp. expressed as: «·« 35 Nitroglycol 23.0 «* · • V Dinitrotoluene 7.1 13 118646

Nitrocellulose (1) 1.6

Wood flour (2) 1.7

Flour (3) 0.7

Ammonium nitrate (4) 65.9 The impact sensitivity of the composition, as measured by falling weight, was about 24 to 25 cm.

Example 2

The composition was prepared using particulate paraffin wax as a retardant. The composition contained the following 10 ingredients, expressed as a mass fraction:

Nitroglycol 26.0

Nitrocellulose (1) 1,3

Wood flour (2) 1,3

Flour (3) 2,0 15 Ammonium nitrate (4) 66.8

Paraffin wax (5) 1.8

Paraffin oil (6) 0.8

The impact sensitivity of the composition, as measured by the falling weight, was about 25 cm.

Example 3

The composition was prepared using particulate paraffin wax as a retardant. The composition contained the following ingredients, expressed by weight: • ·· ·. Nitroglycol 26.0: 25 Nitrocellulose (1) 1,2 • * · ** V Wood flour (2) 1,5 · ::: flour o) 2,1 • · · * · * Ammonium nitrate (4) 66.5

Paraffin wax (5) 2,2 ··: '* · 30 water 0,5 ·· · „, ϊ Composition impact sensitivity, falling weight ···. was about 24 cm.

• · ··· .... · Example 4 • ·. The composition was prepared using a retardant ··· · ... · 35 as particulate paraffin wax. The composition contained the following components, expressed as a mass fraction: 14 118646

Nitroglycol 26.0

Nitrocellulose (1) 1,2

Wood flour (2) 1,4

Flour (3) 2.1 5 Ammonium nitrate (4) 66.5

Paraffin wax (5) 2.2

Water 0.6

Wetting agent (7) 0.02

The composition had an impact sensitivity, measured by a falling weight of 10, of about 24 cm.

Example 5

The composition was prepared using particulate paraffin wax as a retardant. The composition contained the following ingredients, expressed by weight: 15 Nitroglycol 26.0

Nitrocellulose (1) 1,3

Wood flour (2) 1,5

Flour (3) 1.5

Ammonium nitrate (4) 67,7 20 Paraffin wax (5) 2,0

The impact sensitivity of the composition, as measured by the falling weight • · ·. · ·, Was approximately 25 cm.

> 4 * ϊ * Explanations; 1. Nitrocellulose Bofors Dynamite NC, 12.2 - 12.5% typ- • * ·! 25 pe.

:, i. 2. Wood flour having a particle size of about 250 μπι.

3. Rye flour with a particle size of less than 100 μπι.

• · »4. Particulate ammonium nitrate salt, which has been ground .. to a particle size of about 200 μπι.

• i • 30 5. Paraffin Wax AW 3501 (Ter Hell Paraffine, Germany) with a particle size of about 600 μπι and a softening temperature of about: ***: 54 58 ° C.

6. Paraffin oil having a melting point of about -18 ° C.

7. Moisturizing agent SAA (Nippon Oil and Fats).

• · 35 ·· · • · · • * e ·

Claims (7)

118646 An explosive composition in semi-plastic, pasty or slurry form containing more than 5 to 10% by weight of at least one liquid nitric acid ester compound gelled with nitrocellulose, at least one crystalline powdery component comprising an oxidizing salt, and a retardant, characterized in that: that the retardant comprises 0.5 to 10% by volume of the composition of solid particles that are softer or easier to deform than the particles of said crystalline powder component, and that the retardant particles have a weight average particle size greater than the weight average crystalline powder component. The explosive composition of claim 1, wherein the liquid nitric acid ester compound is nitroglycerin or nitroglycol. The explosive composition of claim 1, wherein the retardant particles have a melting or softening temperature higher than the intended operating temperature of the explosive composition prior to ignition, preferably above 50 ° C. An explosive composition according to claim 1, wherein the retardant particles have a Moh hardness less than 1. ···: 25 An explosive composition according to claim 1. · · · ··· · a particle size greater than 2 times the crystalline powder component of the retardant particles! • ko. The explosive composition according to claim 1, wherein the retardant is a wax, preferably petroleum wax. * ·· The explosive composition of claim 1 ***. mush, the volume of the retardant being less than • M .... · the amount of crystalline powdery component in the explosive composition. Sessa. «·· • t • · * · * · · · 118646 Patentfcrav