US3345224A

US3345224A - Dry-appearing explosive composition containing a porous material capable of releasing absorbed liquid at extrusion pressures

Info

Publication number: US3345224A
Application number: US401246A
Authority: US
Inventors: George L Griffith
Original assignee: Trojan Powder Co
Current assignee: Trojan Powder Co
Priority date: 1964-10-02
Filing date: 1964-10-02
Publication date: 1967-10-03
Anticipated expiration: 1984-10-03

Description

United States Patent No Drawing. Filed Oct. 2, 1964, Ser. No. 401,246 20 Claims- (Cl. 149-38) This invention relates to explosive compositions especially formulated for loading into explosive containers by extrusion, and, more particularly, to explosive compositions which may be dry-appearing particulate materials under normal conditions but which under extrusion pressure acquire a semisolid or thioxotropic consistency, and are extrudable in consequence.

The packaging of ammonium nitrate explosives presents a, particularly severe problem, from the standpoint of economics. Ammonium nitrate is a cheap raw material, which can be sensitized rather inexpensively with fuel oil or some other form of carbon or carbonaceous material to form what are termed the nitrocarbonitrates, which have explosive properties. Such mixtures can be brought in bulk to the explosive site, Where they can be filled directly into small diameter bore holes having a diameter of as low as one inch, and then shot. Using conventional explosive packaging procedures, it has been practically impossible to package an inexpensive product in a practical manner at a price sufficiently low to be competitive with the ammonium nitrate-fuel oil bulk compositions which can be blown directly into the holes without packaging.

The packaging of gelled explosives hasalso presented a problem. These are difiicult to package in an efiicient man ner so that they can be sold at a price which is competitive with. ammonium nitrate-fuel oil compositions. These difiiculties basically are due to the lack of a method for pack aging long tubes in an economical manner.

Casings of any desired length can be fabricated from plastic materials, such as regenerated cellulose, polypropylene, and the like. These are extruded in the desired diameter, and then filled by means of a long loading tube or nozzle, through which the filling material is extruded into the casing. This method has been used for many years in the manufacture of sausages in the meat industry. However, it is not adapted for explosive compositions.

In the first place, the known explosive compositions of a consistency desirable for such packages are virtually impossible to extrude. If the explosive is fluid, it extrudes and packages easily, but the package is flimsy and limp.

If the explosive is semi-solid or solid, the packages are 1 self-supporting, but such consistencies can be extruded only at rather high pressures, at which the composition may be unsafe to handle, due to the pressures and heat generated, and which increase as the extruded column increases in length. As a practical matter, the limiting extrusion pressure at which semi-solid explosives are safe to handle is rather low, of the order of 25 to 40 p.s.i., so that it is impossible to extmde more than rather short columns, not much longer than normal length cartridges. This prevents realization of the real advantage of extrusion: the preparation of explosive packages of practically unlimited length.

Moreover, the preparation of a desirably thick semisolid explosive composition also presents mixing problems.

Such a composition cannot be simply blended in a dry 3,345,224 Patented Oct. 3, 1967 mixer, as in the case of powdered explosives, but requires special mixers capable of producing a homogeneous thick mix. Most of the equipment capable of doing this is extremely complex, and can introduce an explosive hazard. In addition, such material is impossible to screen in the usual way, since it forms dough-like lumps or globs, and would have to 'be screened manually, if at all.

In accordance with the invention, explosive compositions are provided which are especially formulated for manufacture in conventional dry mixing equipment and yet are adapted for extrusion in conventional equipment at safe extrusion pressures. Under ordinary conditions these compositions can be solid and dry-appearing and particulate, and after extrusion into containers made of flexible material give packages which are self-supporting. This unique combination of physical properties is obtained by incorporating in the explosive composition a porous material capable of absorbing a sufficient amount of the liquid used as a dispersing medium to convert the mass into a dry mix workable in ordinary mixing equipment at normal atmospheric pressures, but convertible into a semisolid or thixotropic composition under the pressures required for extrusion using conventional equipment. Under such extrusion pressures the liquid is'expressed from the porous material which thus supplies a sufficient amount of free liquid in the composition at that time to convert the solid dry-appearing mass into an extrudable semi-solid or thixotropic gel or slurry.

The explosive compositions in accordance with the invention contain, as the essential ingredients, in addition to the porous material, ingredients to impart an explo sive eflFect, comprising an explosive such as a liquid explosive or any inorganic oxidizer, one or more fuels,-and optionally, a sensitizing explosive, together with a sufiicient amount of liquid, such as Water or oil, expressible from the porous resilient material under extrusion pressures to bring the mixture to a semi-solid or thixotropic consistency. Such pressures are well known, and normally lie within the range from 10 to about 40 p.s.i.

The semi-solid or thixotropic extrudable consistency is defined in terms of the pressure required to extrude the composition through a conventional extrusion nozzle. This pressure does not vary appreciably over nozzle dimensions in the usual diameters of from one to five inches and lengths of from ten inches to two feet, and practically speaking such variation can be ignored. It has been determined that a composition in accordance with the invention that is extrudable at at least 10 p.s.i. at room temperature is sufficiently fluid to be, operative. Compositions extrud able at lower pressures are undesirably fluid at room temperature. Preferably, the minimum pressure is 25 p.s.i. The upper limit is imposed only by the pressure at which the explosive composition is safe to handle, and is not critical otherwise. Usually, a practical upper limit is 50 p.s.i.

The semi-solid or thixotropic consistency is due to the presence at extrusion pressures of enough free liquid to impart the desired consistency and extrudability to the solid ingredients. Some particulate explosives and sensitizing explosives are capable of absorbing surprisingly large amounts of liquids, and such liquid is not expressed to any significant extent at extrusion pressures, because of the noncompressibility of the particles. Hence, such liquid is not available for the purposes of the invention. Also, all of the liquid absorbed by theporous material may not be expressible except at unsafe extrusion pressures. The

liquid added in the compositions of the invention is always Q enough more than this unavailable amount to impart the desired consistency and extrudability at extrusion pressures but less than will form a free-flowing of fluid slurry at such pressures.

As little as 0.5% expressible liquid may suflice, but more may be required to make the composition extrudable at pressures of 50 psi. or less. The practical upper limit is set by excessive fluidity at extrusion pressures and dissipation of the explosive power. In most cases, the preferred range of expressible liquid content will be from about 0.5 to 20%, although in some cases as much as 30% can be used. In these proportions, the viscosity of the liquid is of course a factor to be taken into account.

Water or oil are preferred liquids, although any inert liquid can be used. Any oil can be used as the suspending medium. Petroleum-derived hydrocarbon oils are readily available, and are preferred because of their low cost. The viscosity can range from very thin such as 50 SSU at 100 F., to quite heavy, up to about 1200 SSU at 100 F. Kerosene, fuel oil, 100 SSU paraifin oil, light straw parafiin oil, SAE 10 to 50 lubricating oils, and hydraulic oils, are exemplary.

If oil is the only liquid present, the slurry may be seriously deficient in oxygen, reducing sensitivity and also brisance and power. Water thus is usually also added in a small amount, to mitigate this deficiency and restore sensitivity, brisance and power to an acceptable level. Surprisingly large amounts of water can be added without separation of oil occurring.

Water is thinner than most of the oils that would be used, and will consequently reduce the consistency of the slurry. Less water than oil of the same viscosity is required to bring the mixture to the desired semi-solid or thixotropic consistency, so that a mixture of oil and water may be more advantageous than oil alone for this reason. In all cases, oxygen balance must also be taken into account in determining the proportions of water and oil that should be used for a given explosive slurry. Good proportions for most sensitized slurries, using finely divided nitrate oxidizer and sensitizer, taking all of the above factors into consideration, are from 2 to 10% water, with from 5 to 20% oil. If such slurries have unduly high fluidity, this can be reduced by addition of an appropriate amount of thickening agent.

When water alone is used, the amount can be rather small, less than will produce a slurry of the explosive mixture, but enough to impart to the composition a semisolid consistency. Such an amount usually in addition renders the composition insensitive to shock. Surprisingly, although water desensitizes the mixture, it does not reduce the explosive power, but increases it. As little as 0.5% water may suflice, and usually not more than 20% need be used.

The amount of liquid added invariably exceeds that capable of being absorbed by the components of the mixture, and for the purpose of absorbing this excess liquid, an inert porous material is added in accordance with the invention. The amount of such material added usually is sufficient to take up all of the excess liquid, and convert the composition into a solid dry-appearing particulate mass at atmospheric pressures, but insuflicient to retain all of the liquid under extrusion pressures, so as to ensure release of suflicient liquid under such pressures to permit the development of the desired semi-solid or thixotropic consistency desired for extrusion. Thus, the amount of such inert porous material will depend upon the semisolid or thixotropic consistency desired under extrusion pressures, and the amount of unabsorbed or free liquid, and usually will be within the range from about 0.2 to about 20%, and preferably from about 0.5 to about 5%.

As the porous material, there can be used any particulate porous inorganic or organic material, capable of absorbing, by capillary attraction or otherwise, preferably in an amount of at least 2.5 times its weight,the liquid used to suspend or disperse the explosive composition of the invention, and of expressing such liquid at extrusion pressures, which usually lie within the range from about 10 to about 50 psi. The material should be of small particle size, and preferably is inert. The material should not expand too greatly after absorbing the liquid.

The porous material may be reactive under explosive conditions, and serve as an additional fuel. In this event, it will have to be taken into account in the oxygen balance of the explosive mixture.

A preferred material is expanded vermiculite, which is an inert material. Vermiculite is a hydrated magnesium aluminum iron silicate, containing approximately 38% SiO 21% MgO, 15% A1 0 9% Fe O 5 to 7% K 0, 1% CaO, and 5 to 9% water. When heated to about 2000 C., it has the property of expanding to from 6 to 20 times the volume of the unexpanded material, and the expanded vermiculite has the property of absorbing very large amounts of water, ranging from 200 to 500% by weight. The material is soft and pliable, and breaks down readily under extrusion pressures.

Also useful are the silica-aerogels, which may be formed from silica, alumina, and other gel-forming metal oxides, silica flour and the bentones. Typical silica aerogels are those manufactured by Monsanto Chemical Company and marketed under the trade name, Santocel, such as Santocel C, Santocel A, Santocel AR, 'Santocel ARD, Santocel AX, Santocel CDV and Santocel CDVR. Other materials are fumed silica made by a combustion or vaporization process, and Linde silica flour, made by burning silicon tetrachloride and collecting the combustion products on cold plates analogous to the production of carbon black.

Particulate porous plastic sponges can be used, such as, for example, a polyurethane sponge, nylon sponge, cellulose sponge, polyvinyl chloride sponge, and sponge rubber (latex). Many of these plastic materials, such as cellulose, latex and polyurethane foams are reactive under the explosive conditions and should be considered as fuels when determining the oxygen balance of the composition.

The particle size of the porous material is not critical, but it should in general be less than 6 mesh. In the case of vermiculite, a preferred material has from 88 to 92% through 6 mesh retained on 35 mesh ('U.S. Sieve Series).

The absorbency for the free suspending liquid of any given porous material, as well as the pressures at which the absorbed liquid can be expressed therefrom, are dependent on the free liquid that is used. For optimum results, the liquid and porous material must be nicely matched so that the combination meets the requirements given above. For example, vermiculite has been found to be satisfactory when water is the absorbed liquid, while cellulose sponge has been found unsatisfactory with water but excellent With petroleum oils. Table I summarizes the absorbency and release characteristics for water and oils of vermiculite, polyurethane, rubber and cellulose sponge materials, and Celite which are effectively used in the invention.

Absorbency and liquid expressibility of the materials was determined by the following test procedure: Water was added with mixing to the carrier material to the point where excess water appeared-this was designated saturation ratio. After the saturation ratio was determined for the materials listed, the moisture release characeristics were determined for a 10 gm. dry weight basis of carrier material by placing the saturated material in a Plexiglas cylinder having a 1.25" inside diameter with M seepage holes placed around the circumference and along the length of the cylinder at spacings. The cylinder containing the material was then mounted on a stationary abutment and a 1%" piston placed in the cylinder. The pressure listed in the table was then applied by means of an air cylinder. The moisture released from the material escaped through the holes in the cylinder wall, and the weight loss was calculated in percentage moisture released. 1

' The invention is useful with liquid explosives, such as, for example, the nitric eters or organic nitrates, and the nitroamines, for example, trinitrogylcerine,

vermiculite, Grade No. 2-.-- 3.8:1 5. 3 18.4 35.8 48.9 55. 4 vermiculite, Plaster Grade 3.8:1 2. 7 42. 1 Cellulose Sponge (#6 Sieve). 4:1 21 Cellulose Sponge 4. 6:1 53

D0 11:1 15.1 23. 6 45. 5 61. 8 72. 8 83. 7 Polyurethane Foam 3. 4:1 24 34 40 51 56 1 66 0 6. 4: 1 5 9 12 26 31 43 Foam Rubber- 5. 4:1 7 15 41 46 50 67 Celite- 6. 2:1 4 7 30 4O 49 62 Do- Water 3. 8:1

- 1 At 45 p.s i

2 Formed aslurry that leaked out of the equipment, due to excessive fluidity.

The greatest amount of moisture released was obtained with the No. 2 grade vermiculite and the cellulose sponge- 6 sievesatisfyin-g the two criteria in that the desired material can hold a high ratio of water and again re lease the water.

The results obtained indicate that the perlite is the least absorptive of the materials tested. The Celite and vermiculite will absorb equal amounts of water and the cellulose sponge is by far the most absorbentapproximately 2% times that of the other material.

It would be expected that the porous material, since it is inert and nonexplosive, would reduce the sensitivity of the explosive compositions of the invention. In fact, it does not, and the reason it does not is thought to be the air content of the pores, which contain trapped air even when the material is apparently saturated with liquid.

As the explosive ingredient, there can be used an inorganic oxidizer, such as an inorganic nitrate or chlorate, or perchlorate, ammonium nitrate, ammonium chlorate and ammonium perchlorate being the principal inorganic oxidizers. The nitrates, chlorates and perchlorates of alkali and alkaline earth metals, such as sodium nitrate, potassium nitrate, barium nitrate, strontium nitrate, calcium nitrate, sodium chlorate, potassium chlorate, barium chlorate, sodium perchlorate, potassium perchlorate, barium perchlorate, and calcium perchlorate are exemplary supplementary inorganic nitrates, chlorates and perchlorates. 4

Mixtures of nitrates, chlorates and perchlorates, of nitrates and chlorates, of nitrates and perchlorates, and of chlorates and perchlorates, can be used. Sodium nitrate is preferred as the nitrate for use with ammonium nitrate.

In this composition, the relative proportions of ammonium nitrate, chlorate or perchlorate and other inorganic nitrate, chlorate or perchlorate are important for good explosive shock and power. The ammonium oxidizer is employed in a proportion within the range from about 50 to 100%, and the other oxidizer or oxidizers in a proportion within the range from 0 to about 50% of the total oxidizer. For optimum power, the proportions are from 80 to 90% ammonium oxidizer, and from 10 to 20% other oxidizer or oxidizers. An oxidizer mixture of approximately ;80 to 90% ammonium oxidizer and 10 to 20% of the other oxidizer or oxidizers is in most cases the best. The particular proportions of oxidizers selected within these ranges will depend upon the sensitivity and explosive effect desired, and these in turn are dependent 'upon the particular nitrate, or chlorate or perchlorate used.

The inorganic oxidizers can be fine, coarse, or a blend of fine and coarse materials. Mill and prill inorganic oxidizers are quite satisfactory. For best results, the sodium oxidizer and ammonium oxidizer should be finegrained.

or glyceryl trinitrate, methyl nitrate, ethyl nitrate, npropyl nitrate, and isopropyl nitrate, dinitrogylcerine, nitrogylcide, tetranitrodigylcerine, nitrogylcol, trinitrophenoxyethyl nitrate, 2,4,6-trinitrophenyl nitraminoethyl nitrate (pentryl), hexanitro diphenyl aminoethyl nitrate, trimethylene glycol dinitrate, and propylene glycol dinitrate. The porous material absorbs the liquid and produces a dry appearing mass, just as in the case of the inorganic oxidizer explosive compositions. However, more of the porous material may be needed when a liquid explosive is used, particularly if a dispersing liquid is used as well as to obtain the desired semi-solid consistency.

3 5 With an inorganic oxidizer there can be used a sensitizing explosive. The preferred sensitizing explosive is nitrostarch, but any sensitizing explosive can be used, alone or in admixture. Known sensitizing explosives include, for example, trinitrotoluene, dinitrotoluene, pentaerythritol 40 tetranitrate, dipentaerythritol hexanitrate, mannitol hexanitrate, sorbitol hexanitrate, sucrose octanitrate, ethylene glycol dinitrate, diethylene glycol dinitrate, trimethylolethane trinitrate, nitroglycerine, Pentolite (an equal parts by weight mixture of pentaerythritol tetranitrate and trinitrotoluene), Cyclonite (RDX, cyclotrimethylene trinitramine), nitrocellulose, Composition B (a mixture of up to 60% RDX, up to 40% TNT, and 1 to 4% wax), Cyclotol (Composition B without the wax), tetryl, and smokeless powder such as carbine ball powder. Nitrostarch in combination with a mixture of ammonium nitrate and other nitrate is preferred because it gives the greatest explosive effect. v

The relative proportions of oxidizer and sensitizing explosive, if used, will depend upon the sensitivityand explosive shock wave desired, and these, again, are dependent upon the particular nitrate and sensitizer. These proportions are not critical in any way. From about 25 to about 30% sensitizing explosiveand from about 50 to about 70% oxidizer give the best results.

When the amount of sensitizing explosive is in the lower part of the range, or is absent, a large'initiator or booster is needed. At amounts beyond 40%, the sensitizing eifect falls off, and is no longer proportional to the amount of sensitizing explosive added, and therefore amounts beyond 40% are not usually used.

Sensitizingexplosives of any particle size can be used. They can, for example, be fine, coarse or a blend of fine and coarse material. Some materials, such as nitrostarch, are commercially available as very finely-divided powders, and so also is trinitrotoluene. Such available materials are employed to advantage, because in most cases they tend to produce compositions having a greater explosive effect. 7

In addition to thesematerials, as has been indicated,

the explosive compositions of the invention include a particulate metal fuel, for example, flake aluminum, atomized aluminum, ferrophosphorus and ferrosilicon. A metal fuel will usually comprise from about 0.5% to about 30% of the composition, preferably from 0.5 to in the case of aluminum. In addition to the metal fuel, a carbonaceous fuel can be included, as an optional ingredient, such as powdered coal, petroleum oil, coke dust, charcoal, bagasse, dextrine, starch, wood meal, flour, bran, pecan meal, and similar nut shell meals. A carbonaceous fuel when present will usually comprise from about 0.5 to about 30% of the mixture. Mixtures of metal and carbonaceous fuels can be used, if desired.

An antacid, or other stabilizing material, such as zinc oxide, calcium carbonate, aluminum oxide, and sodium carbonate, can also be added. Such ingredients will comprise from about 0.3 to about 2% of the mixture.

The explosive composition of the invention is readily prepared by simple mixing of the ingredients. Because the porous material absorbs substantially all free liquid prescut, the preparation of the composition is greatly facili tated, since it can be processed like any other particulate explosive composition. Because the composition is not semi-solid as formulated, but solid and dry-appearing, it can be prepared in a conventional dry mixer and screened, using screens having a mesh size of 4 openings per square inch and even smaller, in contrast with a semisolid material which must actually be pressed manually or physically through the screen.

In order to ensure absorption of free liquid, all or part of the liquid, such as water and/or oil, is first mixed with the porous material, such as the vermiculite, and is taken up thereby. Some of the liquid can be added separately, if desired, but this should not exceed the amount that can be absorbed by the other solid materials including the inorganic nitrate, sensitizing explosives, fuel and antacid to form a homogeneous blend in a conventional dry mixer. A ribbon mixer, or a single shaft paddle mixer, for instance, can be employed. The solid materials usually are mixed first, and the porous material and absorbed liquid are then added with further stirring. The resulting mix is then screened in the usual way.

The absorbed liquid generally stays entirely within the porous material until the mixing and screening operations have been completed. Thereafter, the absorbed liquid content thereof may be transferred to drier components of the mix, and eventually equilibrium is reached with the other solid materials present, in accordance with their relative liquid absorption tendencies. This depends upon their porosity and the affinity for the liquid vis-a-vis the porous material.

This explosive composition can then be extruded into open-ended cartridges, using conventional extrusion equipment, to produce the final explosive package.

The cartridge container can be formed of any container material. Heavy cardboard is inexpensive, and available in sufficient thickness of wall, and is therefore preferred. The cartridge container can also be formed of plastic and cellulosic materials such as polyethylene, ethylcellulose, cellulose acetate, polypropylene, poytetrafluoroethyene, nylon, polyvinyl chloride, polystyrene and polyvinylidene chloride, and nonferrous metals, such as tin, copper and aluminum. Fibrous materials such as wood, paper, and cardboard can be used as such, or, if desired, can be impregnated with a synthetic resin to improve strength and water-resistance.

The explosives of the invention, being relatively insensitive, are fired with the aid of a booster charge. Any conventional cap-sensitive booster charge available in the art can be employed. Pentaerythritol tetranitrate, Composition B and pentolite are exemplary. The booster charge preferably is non-shock or -impact sensitive. The amount of booster charge required depends, of course, upon the amount and sensitivity of the explosive mixture.

The following examples, in the opinion of the inventor, represent preferred embodiments of his invention:

. Example 1 Grade No. 2 vermiculite was obtained having the following screen analysis:

2.0 parts of this vermiculite was mixed with 5.0 parts water and allowed to stand for one-half hour until all of the water had been completely absorbed.

The solid ingredients listed in the explosive formulation below were blended in a paddle mixer until a homogeneous solid blend had been obtained. 24.5 parts of the water-soaked vermiculite was then added, and mixing continued until the vermiculite had been homogeneously dispersed. The blend was then screened through a screen having four openings per square inch. A portion of the mix was left in the mixer until balling occurred, a total of 12minutes mixing time.

For comparison purposes, an identical mixture was prepared, labeled Control in the table below, employing cellulose sponge in place of the vermiculite. The cellulose sponge was saturated with water in the same manner as the vermiculite, and took up 145 parts of water for each 20 parts of sponge. Because of the greater amount of water, a lesser amount of cellulose was required to give the same carrier-to-water ratio in the explosive mixture. During mixing, this mixture balled after one-half minute of mixing, indicating that the cellulose had released its water very quickly to the mix, which is undesirable.

The composition of the final explosive mixture was as follows:

Percent by Weight Example 1 Control Nitrostareh, Wet (23% E 0) 17. 00 17. 00 Ammonium Nitrate Prills (crushed) 53. 50 54. Sodium Nitrate, grained 15.00 15. 00 Zinc Oxide 0. 60 0. 60 Aluminum, flaked 1. 75 1. 75 Sodium Thiosuliate, an drous 0.30 0.30 Oil No. 5 0.25 '0. 25 Pecan Meal 3. 00 3. 00 Sodium Carboxymethylcellulose 1.30 1. 30 Guar Gum 0.30 0. 30 N o. 2 vermiculite/Water (20/50) 7. 00 Cellulose Sponge/Water (20/145) 5. 60

Each of these formulations was extruded in conventional equipment at 15 to 30 p.s.i. into plastic 1 /2 inch x 12 inch cartridges and plastic 1 /2 inch x 14 foot cartridges. These were subjected to the usual standardized tests to determine sensitivity and ballistic pendulum value. The density and moisture content of the mixture also were determined, with the following results:

It is apparent from the sensitivity data that the vermiculite, although in a greater weight than the cellulose, had no adverse efiects on the sensitivity of the composition, even though the moisture content of the final mix was higher. The cellulose decreased sensitivity, and this, in conjunction with the lesser mixing time, shows that cellulose sponge is not a desirable porous material for use with water as the suspending liquid in the compositions of the invention.

The results for cellulose sponge in the above example, using water as the liquid, are to be contrasted with the data in Table I, when No. 2 fuel oil and oil No. 5 (SAE No. 30 engine oil) are used as the free liquid. The cellulose sponge does not readily give up these liquids at pressures under 25 p.s.i. in the 1 /2 inch cylinder test, but has a release curve comparable to the No. 2. vermiculite with water. This shows that the elfectiveness of the porous material depends not upon the porous material itself, but upon the liquid that is used with it. Both must match, so that the combination will give satisfactory results in the compositions of the invention.

Example 2 A second extrud-able nitrostarch explosive composition was prepared using the vermiculite from Example 1, to the formulation below.

The composition was mixed and extruded as in Example l.

A second nitrostarch composition was made, as a control, identical to the above, but adding water in the liquid state without the vermiculite.

Percent by Weight Example 2 Control N itrostarch, wet 14. 14. 00 Ammonium Nitrate, mill grained 42. 40 42. 30 Ammonium Nitrate, E-2 pri1ls 25. 00 25.00 Sodium Nitrate 9. 24 9. 24 Zinc Oxide O. 20 0. 20 Aluminum, flake--- 1. 20 1. 20 Ritfle Coal, F1 2. 50 2. 50 Oil No. 0.25 0. 25 Wheat Flo 3. 50 3. 50 Carbon Black 0. 01 0.01 Water. 1. 50 Sodium Thiosulfate 0.30 0. 30 No. 2 Vermieulite/Water (0.4/1.0) 1. 4O

TABLE III I Example2 I Control Screened Fraction Remaining on No. 4 1.0% 5.7%.

Screen.

Density- 1.36- 1.445.

D Sensitivity 1%2: 8' No. 2 D-fi.

The results emphasize the improvements obtained using the porous material of this invention: there is less balling during mixing, as shown by the decrease in material retained on a No. 4 sieve. There is also an improvement in sensitivity, from a No. 6 detonating cap to a 'No. 2 detonating cap.

Example 3 An cxtrudable explosive mixture was prepared, using 10 the procedure of Example 1, and having the composition below.

Percent by Weight Example 3 Control TNT grained, wet (10% water) 18. 18. 90 Ammonium nitrate, prilled (crushed, M6

screen) 49. 70 52. 15 Sodium nitrate, mill 15. 00 15. 00 Zinc Oxide 0. 60 0. 60 Aluminum, fiake 1. 75 1. 75 Nut Meal 2. 00 2. 00 Guar Gum, Jaguar EXFC50 0. 30 O. 30 Sodium Carboxymethylcellulo 1. 30 1. 30 Oil No.5 0. 25 0.25 Sodium Thiosulfate 0.30 0. 30 Water/vermiculite (3/1) 9. 90 Water. l. 86 vermiculite- 5. 59

A second mixture was prepared to the same composition, but adding the water and the vermiculite separately.

The first mixture was mixed in a paddle mixer for seven minutes without balling, and passed readily through a No. 4 sieve. After one minute of mixing the second mixture was completely balled, had to be dug out of the mixer, and could not be screened through a inch screen. This shows that the vermiculite must contain the free liquid at the time of mixing, or it will be inefiective in preventing balling.

Each of these formulations was extruded in conventional equipment at 15 to 30 psi. into plastic 1 inch x 12 inch cartridges and plastic 1 /2 inch x 14 foot cartridges.

Having regard to the foregoing disclosure, the following is claimed as the inventive and patentable embodiments thereof: v

1. An explosive composition of a dry-appearing but extrudable consistency, consisting essentially of an explosive selected from the group consisting of inorganic oxidizer salts; liquid explosives; sensitizing explosives; and mixtures of the same, in an amount within the range from about 99.95 to about 75% by weight, a fuel selected from the group consisting of metal fuels, carbonaceous fuels, and mixtures of the same, in an amount within the range from about 0 to about 30% by weight, a nonexplosive liquid in an amount within the range of from about 5 to about 30% by weight that is wholly absorbed on the solid ingredients, whereby the composition has a dry-appearing consistency with substantially no free liquid in the spaces between the particles of the composition, and a porous particulate material that is capable of absorbing nonexplosive liquid and of releasing the absorbed liquid under pressure, in an amount within the range from about 0.05 to about 25% by weight, having absorbed thereon a sufiicient amount of the nonexplosive liquid that is released at extrusion pressures of from about 10 to about 40 p.s.i. to convert the composition at such pressures to a semisolid extrudable consistency.

2. An explosive composition in accordance with claim 1 in which the fuel is particulate aluminum.

3. An explosive composition in accordance with claim 1 in which the explosive comprises an inorganic nitrate.

4. An explosive composition in accordance with claim 1 in which the explosive comprises nitrostarch.

5. An explosive composition in accordance with claim 1 in which the explosive comprises trinitrotoluene.

6. An explosive composition in accordance with claim 1 in which the explosive comprises trimethylolethane trinitrate.

7. An explosive composition in accordance with claim 1 in which the explosive comprises pentaerythrit-ol tetranitrate.

8. An explosive composition in accordance with claim 1 in which the explosive comprises double base nitrocellulose powder.

9. An explosive composition in accordance with claim 1 in which the explosive comprises cyclotrimethylene trinitramine.

10. An explosive composition in accordance with claim 1 in which the explosive comprises ethylene glycol dinitrate.

11. An explosive composition in accordance with claim 1 comprising a liquid in an amount to suspend the explosive ingredients.

12. An explosive composition in accordance with claim 11 in which the liquid is water.

13. An explosive composition in accordance with claim 11 in which the liquid is oil.

14. An explosive composition in accordance with claim 1 in which the porous particulate material is expanded vermiculite.

15. An explosive composition of dry-appearing but extrudable consistency consisting essentially of from about 10 to about 75% by weight of an inorganic nitrate oxidizer comprising from about 50 to 100% by weight of ammonium nitrate, and from to about 50% by weight of another inorganic nitrate, from about 5 to about 40% by weight sensitizing explosive, from 0.5 to about 30% by weight of a fuel selected from the group consisting of metal fuels, carbonaceous fuels, and mixtures of the same, water in an amount of from about 0.5 to about 30% by weight that is wholly absorbed on the solid ingredients, whereby the composition has a dry-appearing consistency with substantially no free liquid in the spaces between the particles of the composition, and a porous particulate material that is capable of absorbing water and of releasing the absorbed water under pressure, in an amount within the range from about 0.05 to about 25% by weight, having absorbed thereon a sufficient amount of the water that is released at extrusion pressures of from about to about 40 psi. to convert the composition at such pressures to a semi-solid extrudable consistency.

16. An explosive composition in accordance with claim in which all of the fuel is particulate aluminum.

17. An explosive composition in accordance with claim 15 in which the other inorganic nitrate is an alkali metal nitrate.

18. An explosive composition in accordance with claim 15 in which the porous material is expanded vermiculite.

19. An explosive composition in accordance with claim 15 in which the sensi-tizer is nitrostarch.

20. An explosive composition of dry-appearing but eX- trudable consistency consisting essentially of from about 5% by weight to about 70% by weight ammonium nitrate, from about 5% by weight to about by weight sodium nitrate, from about 5% by weight to about 40% by weight nitrostarch, from about 0.5% by weight to about 30% by weight flake aluminum, fromO to about 30% by weight of a carbonaceous fuel, water in an amount of from about 0.5 to about 30% by weight that is wholly absorbed on the solid ingredients, whereby the composition has a dry-appearing consistency with substantially no free liquid in the spaces between the particles of the composition, and a porous particulate material that is capable of absorbing water and of releasing the absorbed water under pressure, in an amount within the range from about 0.05 to about 25 by weight, having absorbed thereon a sufficient amount of the water that is released at extrusion pressures of from about 10 to about 40 psi. to convert the composition at such pressures to a semi-solid extrudable consistency.

References Cited UNITED STATES PATENTS 2,577,110 12/1951 Cummings 149--56 X 2,991,167 7/1961 Burton 14919 3,132,061 5/1964 Walsh et a1. l4919 X 3,155,554 11/1964 Cook et a1. 14956 X 3,238,074 3/1966 Griffith et al. 149-38 X 3,252,843 5/1966 Griffith et al. 149-46 X 3,260,632 7/1966 Olstowski et a1. 14946 X BENJAMIN R. PADGETT, Primary Examiner.

S. I. LECHERT, JR., Assistant Examiner.

Claims

1. AN EXPLOSIVE COMPOSITION OF A DRY-APEARING BUT EXTRUDABLE CONSISTENCY CONSISTING ESSENTIALLY OF AN EXPLOSIVE SELECTED FROM THE GROUP CONSISTING OF INORGANIC OXIDIZER SALTS; LIQUID EXPLOSIVE SENSITIZING EXPLOSIVES; AND MIXTURES OF THE SAME, IN AN AMOUNT WITHIN THE RANGE FROM ABOUT 99.95 TO ABOUT 75% BY WEIGHT A FUEL SELECTED FROM THE GROUP CONSISTING OF METAL FUELS, CARBONACEOUS FUELS, AND MIXTURES OF THE SAME IN AN AMOUNT WITHIN THE RANGE FROM ABOUT 0 TO ABOUT 30% BY WEIGHT, A NONEXPLOSIVE LIQUID IN AN AMOUNT WITHIN THE RANGE OF FROM ABOUT 5 TO ABOUT 30% BY WEIGHT THAT IS WHOLLY ABSORBED ON THE SOLID INGREDIENTS, WHEREBY THE COMPOSITION HAS A DRY-APPEARING CONSISTENCY WITH SUBSTANTIALLY NO FREE LIQUID IN THE SPACES BETWEEN THE PARTICLES OF THE COMPOSITION, AND A POROUS PARTICULATE MATERIAL THAT IS CAPABLE OF ABSORBING NONEXPLOSIVE LIQUID AND OF RELEASING THE ABSORBED LIQUID UNDER PRESSURE, IN AN AMOUNT WITHIN THE RANGE FROM ABOUT 0.05 TO ABOUT 25% BY WEIGHT, HAVING ABSORBED THEREON A SUFFICIENT AMOUNT OF THE NONEXPLOSVIE LIQUID THAT IS RELEASED AT EXTRUSION PRESSURES OF FROM ABOUT 10 TO ABOUT 40 P.S.I. TO CONVERT THE COMPOSITION AT SUCH PRESSURES TO A SEMISOLID EXTRUDABLE CONSISTENCY.