US 3238074 A
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United States Patent 3,238,074 EXTRUDABLE EXPLOSIVE COMPOSITION OF SEMI-SOLID 0R THIXQTROPIC CDNSISTENCY CONTAINING FLAKE ALUMINUM George L. Griflith, George F. Knotts, and William L. Schwoyer, Lehigh County, Pa., assignors to Trojan Powder Company, Allentown, Pa., a corporation of New York No Drawing. Filed Jan. 30, 1964, Ser. No. 341,437 20 Claims. (Cl. 149-2) This is a continuation-in-part of application Serial No. 197,592, filed May 25, 1962, which in turn is a continuation-in-part of application Serial No. 166,704, filed January 16, 1962, now abandoned.
This invention relates to a new explosive composition especially formulated for loading into ex losive containers by extrusion, and more particularly to high-velocity extrudable semi-solid or thixotropic explosive compositions useful in seismic exploration.
The explosives industry customarily has packaged explosive compositions in individual containers, which are filled with explosive, usually in the form of a dry powder or slurry, and then closed. Such a packaging procedure requires a large, costly, inefficient plant. It is necessary to roll the explosive shell containers in a shell rolling house, after which the empty shells are sent to a punch house where they are filled in a loading or punching machine, either manually or mechanically. The shells are loaded at one station of the machine, crimped at the second station, and expelled for packing at the third station. This procedure is essentially a batch procedure, and it has been impossible to mechanize this such that packaging could be carried out in a completely continuous operation, starting with the formation of the shell and ending with a filled, closed package.
Recently, machinery has been made available which preforms an explosive composition, and this is then wrapped automatically in paper and crimped at both ends, to produce a completed shell rather quickly, as compared to the conventional procedure. This, however, is also an intermittent operation, which produces shells of a fixed length. Due to certain mechanical restriction, as well as the investment cost of the machine, it is not feasible to manufacture finished shells having a length in excess of sixteen inches. Furthermore, the production rate of the machine is rather low, and the finished explosive package requires multiple paper wrappings to lend it sutficient strength to withstand handling and packaging. Paper is costly, and the use of an unusually large amount of paper is undesirable, since paper produces unfavorable fume characteristics when the explosive is detonated.
The packaging of ammonium nitrate explosives presents a particularly severe problem, from the standpoint of economics. Ammonium nitrate is a cheap raw explosive 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. This techniques poses a particularly diflicult packaging problem, since, 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.
A further problem created by individual packaging of explosive compositions arises from the necessity of propagating the charge from one cartridge to another in the 3,238,074 Patented Mar. 1, 1966 train. It has always been necessary to use an explosive composition in the package of such sensitivity that it is capable of shooting through a discontinuous column of explosive, the discontinuity being brought about by the fact that for practical purposes explosives are loaded normally in lengths of less than 24 inches, and usually in lengths of 4 to 8 inches. Thus, an explosive column in a small diameter hole of great length usually consists of four to twelve sticks of powder, and the composition must necessarily have sufiicient sensitivity so that the detonating wave will not die out as it travels through the discontinuous column of a plurality of sticks. Furthermore, a discontinuous colunm has less water resistance, since the point where two shells butt together is the first point at which water desensitizes the composition, presenting a zone through which the shock wave often fails to pass from one cartridge to the next. Obviously, if it were possible to prepare an explosive column of great length, so that a continuous column could be loaded in the hole in place of a discontinuous one, composed of a plurality of sticks in close juxtaposition, it would be possible to use an explosive composition of less sensitivity, since there would be no need to propagate the explosive wave from one cartridge to another. Such a column would also have greater water resistance than the discontinuous one, since there would be no point at which water could enter between one portion of the explosive and another.
The packaging of gelled explosives has also presented a problem. These are difficult to package in an efficient manner so that they can be sold at a price which is competitive to ammonium nitrate-fuel oil compositions. These difficulties basically are due to the lack of a method for packing 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 exposive 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 exposive is semi-solid or solid, the packages are self-supporting, but such consistencies can be extruded only at rather high pressures, at which the com position 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 30 psi, so that it is impossible to extrude 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.
In accordance with the invention, an explosive composition is provided which is especially formulated for extrusion in conventional equipment at moderate safe extrusion pressures, due to the presence of a small amount of particulate aluminum, and that is capable of detonation at a fast rate, and gives a sharper recording line in seismic work than nitroglycerine explosives. This composition has a semi-solid or thixotropic consistency, and is capable of extrusion, and also of retaining its shape after being extruded into the explosives container.
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 over 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 2 p.s.i. at room temperature is sufficiently cohesive at normal atmospheric conditions to be operative. Compositions extrudable at lower pressures are undesirably fluid at room temperature since they may not retain their shape. Preferably, the minimum pressure is 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 40 p.s.i.
The extrudability is imparted by a small amount of particulate aluminum, which greatly aids lubricity. An amount as little as 0.5% aluminum by weight of the explosives composition markedly improves lubricity, and such compositions are extrudable through long, small diameter nozzles, of the order of one to one and one quarter inches in inside diameter. An amount within the range from at least 1% to about 10% is preferred in most cases. There is no critical upper limit from the standpoint of extrudability, although at amounts in excess of 10% flake aluminum may dry out the mixture somewhat. However, the aluminum also serves as a fuel, and the maximum amount will be determined by the oxygen balance of the composition, and preferably does not exceed about 5% and would not usually exceed about The type and configuration of particle is important. Flake aluminum is a preferred particulate form, from the standpoint of imparting lubricity, although atomized aluminum, granular aluminum and powdered aluminum, while not imparting lubricity to a noticeable extent, can also be used as fuels. Additional but less desirable lubricants that can also be used, to supplement but not to replace the aluminum, include finely divided graphite, mica, talc, aluminum stearate and zinc stearate. The flake aluminum is preferably less than 30 mesh in size. Excellent lubricity is obtained if at least 6% of the flake aluminum is less than 200 mesh. A preferred material is composed of flaked particles of which at least 60% pass through 200 mesh and at least 90% pass through 120 mesh (US. Standard Sieve Series).
In addition to the lubricity-improving flake aluminum, the explosive composition contains of course ingredients to impart an explosive effect. This composition is based on an inorganic oxidizer, one or more fuels, such as metal fuels (including the aluminum) and carbonaceous fuels, and a sufficient amount of liquid, such as water or oil, to bring the mixture to a semi-solid or thixotropic consistency, and, in addition, the composition may contain as an optional ingredient, a sensitizing explosive, preferably nitrostarch.
As the oxidizer, there can be used 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.
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 of 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 to 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.
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 tetranitrate, dipentaerythritol hexanitrate, mannitol hexanitrate, sorbitol hexanitrate, sucrose octanitrate, ethylene glycol dinitrate, diethylene glycol dinitrate, trimethylolethane trinitrate, nitrostarch, Pentolite (an equal parts by weight mixture of pentaerythritol tetranitrate and trinitrotoluene), Cyclonite (RDX, cyclotrimethylene trinitramine), nitrocellullose, 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.
The relative proportions of oxidizer and sensitizing explosive, if used, will depend upon the sensitivity and explosive shock wave desired, and these, again are dependent upon the particular nitrate and sensitizer. These proportions are not critical in any way. For optimum effect, the oxidizer, is used in an amount within the range from 10 to 75% and the sentizing explosive in an amount within the range from about 0 to about 40% by weight of the explosive composition. From about 25 to about 30% sensitizing explosive and 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 booster is needed. At amounts beyond 40%, the sensitizing effect falls off, and is no longer proportional to the amount of sensitizing explosive added, and therefore amounts beyond 40% are not usually used.
Sensitizing explosives of any particle size can be used. They can, for example, be fine, coarse or a blend or 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.
In addition to these materials, as has been indicated, the explosive compositions of the invention include a particulate metal fuel, for example, the particulate aluminum serving as a lubricity-improving agent, and ferrosilicon. A metal fuel will usually comprise from about 0.5% to about 30% of the composition, preferably from 0.5 to 5%, 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 semi-solid or thixotropic compositions of the invention contain enough liquid to impart the desired consistency to the solid ingredients. Some explosive and sensitizing explosives are capable of absorbing surprisingly large amounts of liquid. The liquid added in the slurries of the invention is always enough more than this amount to impart this consistency, but less than will form a slurry. As little as 0.5% liquid may suflice, but more may be required to make the composition flowalble at pressures of less than 30 p.s.i. The practical, upper limit is set by excessive fluidity, and dissipation of the explosive power. In most cases, the preferred range of 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 oils, up to about 1200 SSU at 100 F. Kerosene, fuel oil, 100 SSU parafl'in oil, light straw paraflin oil, SAE 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.
If the amount of water added exceeds that capable of being absorbed by the components of the mixture, a water-soluble or water-dispersible thickener is added to take up the water, for example, carboxymethylcellulose, methyl cellulose, guar gum, including cross-linked guar gum, psyllium seed mucilage, and pregelatinized starches, such as Hydroseal 3B. The amount of such thickening agent will depend upon the semi-solid or thixotropic consistency desired, and the amount of unabsorbed or free water, and usually will be within the range from about 0.5 to about 5%.
An oil thickener can also be added in the case where oil is used in whole or in part as the fluid. Non-carbonaceous inorganic oil thickeners useful in making thickened oils and greases such as finely divided silica, available under the trade names Cab-O-Sil and Ludox, and silica aerogels, for example, Santocel ARD and Santocel C, and like inorganic gelling agents, such as alumina, attapulgite and bentonite, can be used. Other gelling agents are disclosed in U.S. Patents Nos. 2,655,476 and 2,711,393. These are well known materials, and any of these known to the art can be used. The amount of such thickening agent will depend on the consistency desired, and usually will be within the range from 0 up to about 5%. Enough thickener can be added to gel the oil, and Water-proofing agents such as are disclosed in U.S. Patents Nos. 2,554,- 222, 2,655,476 and 2,711,393 can be incorporated as well to impart water resistance to the gelled slurry.
Some explosives in acordance with the invention may have the desired semi-solid or thixotropic consistency at normal atmospheric temperatures, but may become stiff or hard and inflexible at low temperatures, such as may be encountered outdoors in winter in a northern climate. Such a tendency can be counteracted by addition of a polyhydric alcohol, which depresses the freezing point of the liquid (water) component. Only a small amount of polyhydric alcohol need be used, as little as 0.5% giving a noticeable improvement, but at extremely low temperatures, more may be required. An amount equal to the weight of water, taking into account the oxygen balance, can be tolerated by the explosive without deleterious eifect on explosive power.
Fluidity can also be increased by an appropriate selection of oxidizers to give a eutectic mixture. Calcium nitrate readily forms eutectics with ammonium nitrate. Urea has the same effect. The amount required depends upon the composition of the eutectic. From 1 to 10% urea by weight of the ammonium nitrate is effective. Calcium nitrate is used in an amount from 1% to 10% by weight of the ammonium nitrate.
The explosive of the invention, being relatively insensitive, is 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 explosive mixture is readily prepared by simple mixing of the ingredients. The solid materials, including the inorganic nitrate and sensitizing explosives, particulate aluminum, other metal and carbonaceous fuels, and antacid, if any, would usually be mixed first, to form a homogeneous blend, and the oil, water, and oil and water thickeners, if required, would be added, with stirring to bring the mixture to the desired consistency, semi-solid or thixotropic, at which the composition is not flowable except under a pressure of at least 2 p.s.i.
This explosive composition is then extruded into openended cartridges, using conventional extrusion equipment, to produce the seismic or other explosive device.
The cartridge and booster containers can be formed of any container material. Heavy cardboard is inexpensive, and available in sufiicient thickness of wall, and is therefore preferred. The cartridge and container can also be formed of plastic and cellulosic materials such as polyethylene, ethyl cellulose, cellulose acetate, polypropylene, polytetrafluoroethylene, 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 usedv as such, or, if desired, can be impregnated with a synthetic resin to improve strength and water-resistance.
The explosives of the invention have a high rate of detonation, as high, unconfined, as 5500 meters per sec ond. This high rate of detonation is characteristic of sticks ranging in diameter from 1 to 8 inches, a rather surprising property.
The following examples, in the opinion of the inventors, represent the best embodiments of their invention.
Example 1 An explosive mixture of semi-solid consistency was prepared using dry milled nitrostarch, fine grained ammonium nitrate, fine grained sodium nitrate, flake aluminum, and the additional ingredients noted in the table below. The nitrostarch and mixed nitrates were thoroughly blended, and there were then added the zinc oxide, flake aluminum, guar gum, and then the oil and water. The proportions of the final explosive composition were as follows:
Ingredient: Percent Nitrostarch 27.00 Grained ammonium nitrate 47.25 Grained sodium nitrate 10.75 Flake aluminum 2.50 Guar gum 2.50 Oil No. 1.00 Zinc oxide 1.00 Water 8.00
This composition was quite stiff, and nonflowable at room temperature, but it was easily extruded at a pressure of less than 20 p.s.i. through long 1 /2 inch diameter extrusion nozzles into cartridges two feet long and two inches in diameter, made of heavy cardboard, 0.082 inch in thickness, to approximately 2 /2 inches from the top. A booster charge of Pentolite was filled into the booster container previously fitted into the remaining space, two inches in diameter overall, and 2 /2 inches deep. A mandrel was inserted during the charging to produce a well 7 inch wide and 2 /2 inches deep, in the booster charge, for reception of a blasting cap. The open top of the booster container was then closed by a cardboard cover disk.
A number 6 electric blasting cap was put in the well, and the cartridge then covered with a nose cone made of ethyl cellulose plastic, in such a way that the wires from the blasting cap were pinned against the side of the container, and emerged from around the outside end of the cone. The assembly was then inserted in a bore hole 2% inches in diameter. The cartridge detonated, confined at a detonation rate greater than 5500 meters per second. The explosive shock wave was recorded, and a sharp recording line was obtained.
The standard test for determining ballistic pendulum value gave a ballistic pendulum value of 11. In contrast, a highwelocity seismic gelatin in a container of the same size gave a value of 10.4, and a second commerciallyavailable nitroglycerine explosive gave a value of 10.3.
Example 2 An explosive mixture of semi-solid consistency was formulated using dry milled nitrostarch, ammonium nitrate, and sodium nitrate. The ammonium nitrate and sodium nitrate were both fine-grained. These materials were mixed thoroughly and there were then added zinc oxide, flake aluminum, guar gum, sodium carboxymethyl cellulose, and wood flour, after which the water was added. The proportions of the final explosive mixture were as follows:
Ingredient: Percent Nitrostarch 24.60 Grained ammonium nitrate 51.15 Grained sodium nitrate 10.75 Flake aluminum 2.00 Guar gum 1.00 Sodium carboxymethyl cellulose 0.60 Wood flour 1.50 Zinc oxide 1.00 Water 7.40
This mixture had the consistency of a gelled oil, nonflowable at room temperature, but it was easily extruded at a pressure of about 10 p.s.i. through long 1 inch diameter nozzles into several open-ended cardboard cartridges 1% inches in diameter and two feet long, to within three inches of the top, and the ends of these cartridges fitted with booster containers previously filled with Composition B. The booster containers were 2 /2 inches long, and 1% inches in diameter.
A train of explosives was prepared. One cartridge was fitted into the coupling, butt end in, at the side having fixed teeth. A No. 16 electric blasting cap was put in the wall of another cartridge, the electric wires of the blasting cap threaded through the hole in the coupler, and the top or booster end of the cartridge then thrust in the other end of the fast coupler, fitted with movable teeth, in such a manner as to have its top end abutting tightly against the butt end of the first cartridge. Similarly, other cartridges were fitted in fast couplers, butt end in, and then put together against the top or booster end of the end cartridge in the train, producing a train containing, booster end to butt end, a total of 6 cartridges. This was then inserted in a bore hole two inches in diameter, with the blasting cap-fitted cartridge uppermost, and fired. A sharp recording line was obtained, and the velocity was greater than 5500 meters per second. The ballistic pendulum value was 11.
Examples 3 t0 5 Example Number Ingredient Percent Percent Percent Trimethylolethane trinitrate 24. Pentaerythritol tetrauitrate 24. 6 12. 0 Ammonium Nitrate, mill... 48. 4 61.9 72. 5 Mill Sodium Nitrate Flake Aluminum Jaguar guar gum Sodium Carboxymethyl Cellulose Wood Flou.r Zinc Oxide. Water Density 1. 23
These compositions were quite stiff and nonflowable at room temperature, but they were easily extruded at a pressure of less than 40 p.s.i. through long one inch diameter extrusion nozzles into cartridges 8 inches long and 1% inches in diameter, made of heavy cardboard, 0.082 inch in thickness, and the cartridge was then covered.
The standard test for determining sensitivity in a 2 inch pipe was carried out on these cartridges. In the sensitivity tests, when the scope of the standard caps had been passed there were used progressively, as more powerful initiators, 3 g. pentaerythritol tetranitrate booster, and then 5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 100, 125, 150, and 200 east Pentolite boosters. No. 3 was fired by a No. 8-1O blasting cap, No. 4 by a No. 2 cap, and No. 5 by a No. 8 cap. All compositions were insensitive in the rifle ball test.
9 Examples 6 and 7 An explosive mixture of semi-solid consistency was formulated using Composition B or ball powder as the sensitizing explosive mill ammonium nitrate, and mill sodium nitrate. These materials were mixed thoroughly, and there were then added zinc oxide, flake aluminum, guar gum, sodium carboxymethyl cellulose, and wood flour, after which the water was added. The proportions of the final explosive mixture were as follows:
Example Number Ingredient Composition B 1 "percent" 24. 6 Ball power (Olin WC 820) Mill Ammonium Nitrate Mill Sodium Nitrate Flake Aluminum Jaguar 100 guar gum- Sodium Carboxy'meth Wood Flour Zinc Oxide...
Loading density :do. 1. Sensitivity in 1% pipe gm. PETN- Examples 8 to 10 An explosive mixture of semi-solid consistency was prepared using trinitrotoluene and ethylene glycol dinitrate as sensitizing explosives, mill ammonium nitrate, mill sodium nitrate, flake aluminum, and the additional ingredients noted in the table below. The trinitrotoluene, ethylene glycol dinitrate and mixed nitrates were thoroughly blended, and there were then added the zinc oxide, flake aluminum, guar gum, sodium carboxymethyl cellulose, wood flour, and then the water. The proportions of the final explosive composition were as follows:
Example Number Ingredient Percent Percent Trinitrotoluene, 35 mesh 24. 6 14. Ethylene glycol dinitrate Mill Ammonium Nitrate Mill Sodium Nitrate Flake Aluminum Jaguar 100 guar gum Sodium Carboxymethyl Ce11ulose Wood Flour Zinc Oxide Loading density Sensitivity in 1%" pipe don don
This composition was quite stiff and non flowable at room temperature, and was easily extruded at a pressure of p.s.i. through long one inch diameter extrusion nozzles into cartridges two feet long and 1% inches in diameter, made of heavy cardboard, 0.082 inch in thickness. The open top of the booster container was then closed by a cardboard cover disk.
The standard sensitivity test was carried out in a 1% inch pipe, with the results given in the table.
10 Examples 1] i015 An explosive mixture of semi-solid consistency was for mulated using dry milled nitrostarch, ammonium nitrate, and sodium nitrate. The ammonium nitrate and sodium nitrate were both fine-grained. These materials were mixed thoroughly, and there was then added zinc oxide, flake aluminum, guar gum, sodium carboxymethyl cellulose, and wood flour, after which the water was added. The proportions of the final explosive mixture were as follows:
Example number Ingredient Nitrostareh, percent 40.0 Pentaerythritol tetranitrate, percent 6.0 9.0 12 40. 0 Mill ammonium nitrate,
percent 79. 0 74. 5 57. 0 24. 0 35. 0 Mill sodium nitrate, percent. 7. 5 15. 0 15. 0 Flake aluminum, percent 5. O 1. 0 O. 5 1. 0 O. 5 Jaguar guar gum, percent t 1.0 1.0 3. 5 3. 5 Sodium earboxymethyl cellulose, percent 0.6 1. 5 1. 5 Wood flour, percent 5.0 5. 0 1.0 0. 5 Zinc Oxide, percent 1.0 1. 0 1. 0 1.0 Water, percent 8. 5 12.0 12. 0 8. 5 Sensitivity (1% x 8 cartridges) 1 2 1 l0 2 10-20 No. 2 No. 8
cap cap Loading density 1.23 1 23 1. 35 1. 49 1. 47 Rifle ball testfail fall 1 Grams PETN. 2 Grams Pentolite.
These mixtures had the consistency of a gelled oil, nonflowable at room temperature, but were easily extruded at a pressure of 10 p.s.i. through long one inch diameter nozzles into open-ended cartridges 1% inches in diameter and two feet long.
These were subjected to the sensitivity test in 2 inch pipe, with the results given in the table. Nos. 14 and 15 were subjected to the rifle ball test, and failed.
1. An explosive composition of semi-solid extrudable consistency, consisting essentially of from about 10 to about 75% of an inorganic oxidizer comprising from about 50 to 100% of ammonium oxidizer, and from 0 to about 50% of another inorganic oxidizer, from about 0 to about 40% sensitizing explosive, from about 0.5 to about 30% of flake aluminum to impart lubricity, from 0 to about 30% of a fuel other than the aluminum, and sufficient liquid to bring the composition to a semi-solid consistency at which the composition is nonfiowable at room temperature and extrudable through an extrusion nozzle from one to five inches in diameter and from ten inches to two feet in length at a pressure within the range from about 1 to about 40 p.s.i.
2. An explosive composition in accordance with claim 1 in which all of the fuel is particulate aluminum.
3. An explosive composition in accordance with claim 1 in which the inorganic oxidizer is a nitrate.
4. An explosive composition in accordance with claim 1, comprising nitrostarch.
5. An explosive composition in accordance with claim 1 comprising trinitrotoluene.
6. An explosive composition in accordance with claim 1 comprising trimethylolethane trinitrate.
7. An explosive composition in accordance with claim 1 comprising pentaerythritol tetranitrate.
8. An explosive composition in accordance with claim 1 comprising double base nitrocellulose powder.
9. An explosive composition in accordance with claim 1 comprising cyclotrimethylene trinitramine.
10. An explosive composition in accordance with claim 1 comprising ethylene glycol dinitrate.
11. An explosive composition in accordance with claim 1 in which the liquid is water.
12. An explosive composition in accordance with claim 1 in which the liquid is water and oil.
13. An explosive composition in accordance with claim 1 in which the liquid is oil.
14. An explosive composition in accordance with claim 1 which includes, in addition, from 0.5% to about 5% of a thickening agent for the liquid.
15. An explosive composition of semi-solid extrudable consistency consisting essentially of from about 10 to about 75% of an inorganic nitrate oxidizer comprising from about 50 to 100% of ammonium nitrate, and from to about 50% of another inorganic nitrate, from about to about 40% sensitizer, from about 0.5 to about of flake aluminum to impart lubricity, from 0.5 to about 5% of a fuel, other than the aluminum, and sufficient water to bring the composition to a semi-solid consistency at which the composition is nonfiowable at room temperature and extrudable through an extrusion nozzle from one to five inches in diameter and from ten inches to two feet in length at a pressure within the range from about 2 to about 40 psi.
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 which includes, in addition, from 0.5% to about 5% of a thickening agent.
19. An explosive composition in accordance with claim 15 in which the sensitizer is nitrostarch.
20. An explosive composition of semi-solid extrudable consistency consisting essentially of from about 5% to about 70% ammonium nitrate, from about 5% to about 50% sodium nitrate, from about 5% to about nitrostarch, from about 0.5% to about 5% flake aluminum, frorii 0 to about 7% of a carbonaceous fuel, and sufficient water to bring the composition to a semi-solid consistency at which the composition is nonflowable at room temperature and extrudable through an extrusion nozzle from one to five inches in diameter and from ten inches to two feet in length at a pressure within the range from about 2 to about 40 p.s.i.
References Cited by the Examiner UNITED STATES PATENTS 2,930,685 3/1960 Cook et al 14939 X 3,083,127 3/1963 Griffith et al. 149-41 X 3,121,036 1/1964 Cook et al 1494l X 3,147,163 9/1964 Griflith et al. 149-39 3,153,606 10/1964 Breza et a1. 1494l M CARL D. QUARFORTH, Primary Examiner.
BENJAMIN R. PADGETT, Examiner.