Description:
BACKGROUND OF THE INVENTION
Inorganic oxidizing salt based explosive compositions are well-known in the art. Most of these compositions contain ammonium nitrate as the major inorganic oxidizing salt constituent. Certain other inorganic oxidizing salts have been thought of as less potent or so sensitive and unstable as to be dangerous. In some compositions a portion of the ammonium nitrate has been replaced by other inorganic oxidizing salts such as, for example, sodium nitrate, calcium nitrate, certain perchlorates and other inorganic oxidizing salts. These optional inorganic oxidizing salts have been employed for various purposes, such as economy, fluidizing properties, sensitivity enhancement and the like.
These inorganic oxidizing salt based explosive compositions vary from dry to slurry mixtures containing water and/or other liquids, such as glycols, fuel oils and the like. A typical dry mix known in the art is ANFO which contains ammonium nitrate and fuel oil. Typical slurry explosive compositions contain inorganic oxidizing salts, normally a major portion comprising ammonium nitrate, water, a fuel and/or sensitizer and a thickening agent.
U.S. Pat. Nos. 3,660,181 and 3,713,971 teach compositions which have a fudge point (i.e. salts begin to solidify and the composition thickens) which is above the borehole temperature so that the composition solidifies in the borehole or package. To accomplish this result compositions are prepared at an elevated temperature (e.g. 70°C [158°F], col. 3, line 7 of 3,660,181 or at least 30°C [86°F], col. 3, line 35 of 3,713,917, preferably higher, i.e., 55°C [131°F], col. 5, line 17 of 3,713,917). These systems are designed to firm up (i.e. have a fudge point of about 50°C [122°F] to about 35°C [95°F]. Although this type of composition may be desired in many special circumstances it would be most beneficial if compositions could be prepared at ambient temperatures, e.g. 75°F, which were very mobile or even substantially completely fluid and which remain fluid down to temperatures as low as 10°F or lower. Surprisingly it has been discovered that not only can compositions be prepared which have the above described fluidity characteristic but that the compositions remain sensitive to detonation by a small high explosive booster at such low temperatures even without the presence of sensitizers such as powdered metals, self explosives and the like, even though these constituents can be employed if desired. The present invention concerns such compositions.
SUMMARY OF THE INVENTION
The composition of the present invention comprises, as percent by weight at least about 50 percent of the following mixture: from about 51 to about 85 percent of a mixture of inorganic oxidizing salts consisting essentially of from about 53 to about 95 percent, of calcium nitrate, and the balance consisting essentially of ammonium nitrate; from about 9 to about 35 percent, of at least one water miscible organic fuel and from about 5 to about 21 percent H 2 O, the balance, if any, of the composition comprising at least one additional fuel or sensitizer in addition to said water miscible organic fuel, density control agents, gelling or thickening agents and the like. The amount of water of hydration, if any, associated with the calcium nitrate is included in the total amount of water present. The calcium nitrate content is based on anhydrous calcium nitrate though other than anhydrous calcium nitrate can be employed to prepare the composition. Within the above described ranges it is desirable to adjust the individual constituents of the mixture so that the resulting mixture has an oxygen balance ranging from about +20 to about -8 grams of oxygen per 100 grams of total mix. In addition, the weight ratio of the water miscible organic fuel to calcium nitrate should range from about 0.80 to about 0.20.
Sufficient gaseous voids should be provided in the composition to provide a bulk density therein ranging from about 0.80 to about 1.40 gm/cc.
Oxygen balance as employed herein means the amount of excess or paucity of oxygen (O 2 ) expressed as + grams or - grams of oxygen per 100 grams of total composition when combusted where the combustion products are taken to be CO 2 , H 2 O, N 2 and CaO. If a composition has a negative oxygen balance, there will be insufficient oxygen to combine with all of the hydrogen and carbon and H 2 and CO will be formed upon detonation. If a composition has a positive oxygen balance nitrous oxide compounds will be formed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 graphically illustrates certain data from Example 7.
FIG. 2 graphically illustrates certain data from Example 10.
FIGS. 3-5 graphically illustrate certain data from Example 11.
FIGS. 6-8 graphically illustrate certain data from Example 12.
DETAILED DESCRIPTION OF THE INVENTION
Preferably the composition of the present invention comprises, as percent by weight, at least about 70 percent of the following mixture: from about 55 to about 75 of a mixture of inorganic oxidizing salts consisting essentially of from about 53 to about 85 percent calcium nitrate, and the balance consisting essentially of ammonium nitrate; from about 10 to about 27 percent of a water miscible organic fuel selected from the group consisting of ethylene glycol, formamide, methanol, glycerol, diethylene glycol, or ethanol and mixtures thereof; and from about 7 to about 20 percent of water. The mixture preferably has an oxygen balance ranging from about 0 to +15 grams for optimum sensitivity. The above four constituents should be provided in the designated weight proportions to each other even though other constituents may be included in the total composition. Formamide is especially preferred because of its beneficial effects on both the low temperature sensitivity and fluidity of the composition. Thus, in a more preferred composition at least a portion (i.e. at least about 50% by weight) of the water miscible organic fuel comprises formamide. For economic reasons a portion of water miscible organic fuel may comprise, in addition to formamide, other fuels such as ethylene glycol, propylene glycol, methanol and the like.
The optimum weight ratio of the water miscible organic fuel to calcium nitrate will depend on the particular fuel employed. For example if the fuel is formamide, the weight ratio of formamide to calcium nitrate preferably ranges from 0.30 to about 0.70. If the fuel is ethylene glycol, the weight ratio of ethylene glycol to calcium nitrate should range from about 0.25 to about 0.70.
Water miscible organic fuels which can be employed in the composition comprise organic compounds and mixtures of compounds which are miscible in aqueous solutions of calcium nitrate. Examples of groups of organic compounds which can be employed include certain amines, including primary, secondary, tertiary and quaternary amines; amides; alcohols including both mono- and polyhydric alcohols; alcohol ethers; and low molecular weight carbohydrates (saccharides and polysaccharides). Specific compounds which can be employed include, for example, formamide; glycerol; acetic acid, ethylene glycol monomethyl ether; methanol; ethanol; diethylene glycol; hexamethylene tetramine; hexamethylene tetramine mono- and dinitrate; acetamide, ethylene glycol; propylene glycol; urea; thiourea; butylamine, metyl amine, ethylamine, thio diglycol; mono-, di- and triethanol amines; and mixtures of compatible compounds. Water soluble polymers may also be employed as additional fuels and in some instances also serve as thickening agents. Such polymers include, for example, polyamides, celluloses, galactomammans, e.g., guar, polyols, polyalkylamines, polyethyleneimines and other similar water miscible polymers.
By miscible it is meant that the quantity of defined fuel in said mixtures is substantially completely mixable in the quantity of aqueous calcium nitrate solution present in said mixtures without separation of two liquid phases. Organic fuels which are solid at room temperature will normally produce a thicker, less fluid blasting agent than those organic fuels which are fluid at about room temperature (e.g. 68°-74°F). Preferably an organic fuel is employed which when present in the indicated percent range is completely soluble in the aqueous oxidizer phase.
Inorganic oxidizing salts other than calcium nitrate and ammonium nitrate which can be employed in minor amounts include, for example, alkaline earth metal and alkali metal nitrates, sulfates, chlorates, and perchlorates, and specifically, sodium nitrate, ammonium perchlorate, barium nitrate, ammonium sulfate, sodium sulfate, sodium perchlorate, potassium perchlorate and the like. It has been found that certain of these inorganic oxidizing salts enhance certain explosive characteristics of the calcium nitrate mixture while others may hamper certain explosive characteristics but are advantageous for other reasons. For example, some salts may be employed to balance oxygen at the expense of some other feature such as sensitivity. It has been found that ammonium nitrate tends to increase the sensitivity of the calcium nitrate explosive to a certain degree. Sodium nitrate tends to desensitize the calcium nitrate explosive when employed in amounts greater than about 30 percent by weight of the total composition but it may be employed to adjust the oxygen balance of the compositions. Thus when additional inorganic oxidizing salts are employed it should be determined before hand what effect the salt will have on the final explosive. The inorganic oxidizing salts may be employed in particulate form, in solution or both. Ammonium nitrate is preferred as the additional inorganic oxidizing salt because of its enhancing effect on sensitivity and fluidity within certain prescribed quantity limits.
Supplemental sensitizers and/or fuels in addition to those previously described can also be employed in the present composition to alter or improve certain explosive characteristics of the composition. Those sensitizers and/or fuels normally employed in inorganic oxidizing salt based explosive compositions known in the art can be employed in the present invention. These fuels and sensitizers comprise, for example, metals, self-explosives and non-explosive water insoluble carbonaceous or other fuels such as sulfur and mixtures of two or more of these materials. They are employed in amounts sufficient to enhance the base explosive compositions in the manner desired. For example, metal may be employed in an amount to provide a weight ratio of metal to the base composition of up to 1/1 and more. The particle size distribution of the metal particles will effect certain characteristics of the blasting agent in a manner well known in the art. Finer metal, e.g. minus 200 mesh (U.S. Standard Sieve Series), e.g. paint grade aluminum tends to sensitize the explosive composition to detonation, i.e. the composition can be initiated to detonation with a smaller less powerful initiator while coarser metal tends to increase the power of the composition when exploded, but with less sensitizing effect. For example, the sensitivity of the composition can be enhanced by adding from about 2 to about 10 percent by weight of paint grade aluminum to the mixture. The use of such specific size metals are taught in U.S. Pat. Nos. 3,307,986 and 3,432,371, the teachings thereof being specifically incorporated herein by reference.
Particulate metals which can be employed include, for example, aluminum, magnesium, iron, silicon, titanium, aluminum alloys, magnesium alloys, ferrosilicon, silicon carbide, ferrophosphorous, zinc, boron and other like particulate metals which sensitize and/or function as a fuel in the explosive. Of particular importance are the light metals, e.g. aluminum, magnesium, beryllium alloys thereof and the like. Generally the metals range in size from about -4 to about +325 mesh U.S. Standard Sieve Series, although as shown in the examples -325 mesh metal can be employed to enhance certain characteristics of the composition. For metals which might react with the composition certain inhibitors known in the explosives art may be employed to stabilize the compositions, e.g., certain phosphorous containing compounds and fatty acids.
Self-explosives as used herein refer to those nitrated organic substances which, by themselves, are generally recognized in the art as an explosive and which can usually be detonated with a standard blasting cap. Examples of self-explosives which can be employed include organic nitrates, nitro compounds and nitroamines, such as TNT, pentaerythritoltetranitrate (PETN), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitramine (HMX), tetryl, nitrostarch, and explosive grade nitrocellulose as well as mixtures of the aforesaid and other self-explosives. The self-explosives can be in any of the conventional forms such as flake, pelleted or cyrstalline.
Examples of water insoluble carbonaceous non-explosive fuels and sensitizers include finely divided coal and carbon, solid carbonaceous vegetable products such as corn starch, wood pulp, ivory nut meal and bagasse, organic liquids such as hydrocarbon oils, fuel oils, fatty oils, vegetable oils, and mixtures of two or more of these water insoluble carbonaceous non-explosive fuels. These fuels may be blended into the water based mix with, for example, a suitable emulsifying agent to produce a water-in-oil or oil-in-water emulsion. They can also be used as a coating for non-soluble fuels and other additives such as TNT, particulate metals and the like.
Any grade of calcium nitrate, e.g. anhydrous or hydrated may be employed in the present invention. Anhydrous grade, i.e. substantially free from water of hydration or absorbed water, or mono, di, tri, tetra or any other of the hydrated forms may be employed as well as water or organic liquid solutions of the hydrated calcium nitrate. When hydrated calcium nitrate is employed, the water of hydration is considered in calculating the water content of the explosive. Thus the water present in the explosive may come from water of hydration, water may be added separately or a combination of the two can be employed.
Thickening and/or gelling agents can also be employed in the present compositions. These agents are employed in amounts to provide thickened, free-flowing pumpable to very stiff practically immobile compositions. The physical characteristics desired depend mainly on the ultimate use of the explosive. For example, in water-containing boreholes very strong gels are desired to prevent a leaching out and erosion of the explosive composition. Gelling and/or thickening agents are employed which will swell and/or can be crosslinked in the liquid system containing dissolved Ca(NO 3 ) 2 , water, and the water soluble organic fuel. Examples of suitable gelling agents include synthetic polymers, e.g., polyacrylamide, polyamines; starches; polysaccharides; flours e.g., wheat flour; galactomannan gums, such as guar, karaya and the like. Specific thickening agents which may be employed include polyalkylene glycol, hydroxyalkyl cellulose, potato starch, wheat starch, corn starch, carboxymethyl hydroxyethyl cellelose, methyl cellulose, polyethylene amine, carboxy methyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, and the like. It has been found that cellulosic materials, e.g. carboxymethyl hydroxyethyl cellulose, methyl and ethyl cellulose, and the like, and guar gums are preferred in the present invention. Examples of thickeners which provide thickening and suspending characteristics by physical form include magnesium oxides, asbestos fibers, cotton fibers, glass fibers, wood fibers, and the like.
Various density control agents can also be employed in the present invention. These materials can be employed to decrease the density of the explosive, to sensitize the composition, to alter the energy release of the explosive composition and/or to provide composition which can be more readily exploded under elevated pressures and/or low temperatures. Suitable density control agents include void-containing materials, for example, hollow spheres prepared from metals, clays, glass, thermoplastics, and thermosetting resins and other like materials. Specific examples of void-containing materials can be found in U.S. Pat. Nos. 3,456,589, 3,101,288 and 3,773,573, the teachings of these patents being specifically incorporated herein by reference. Also naturally occurring void-containing materials such as ground corn cobs, bagasse, walnut shells and other like materials known in the art can be employed in the explosive. The carbonaceous thickening, gelling and density control agents also provide additional fuel for the explosive composition. Also void or gaseous generating chemicals may be employed to form gaseous voids in situ. Examples of such chemicals include certain nitrites alone or in combination with sulfamic acid, certain sulfamates, carbonates and bicarbonates. Other such void generating compounds include, for example, combinations of carbonates or bicarbonates and acids, e.g. HC1 and the like. Also gaseous bubbles may be incorporated into the mix during its manufacture, such as by whipping air into the mix which are stabilized with viscosity building polymers and the like.
The compositions of the present invention range from watery clear fluid substances to very thick masses containing particulates, e.g. particulate inorganic oxidizing salts and/or sensitizers, and/or fuels.
The explosive compositions of the present invention may be prepared in the following manner. The requisite amount of water soluble organic fuel and water are mixed together. Any density control agents which may be employed are then added to this mixture. Particulate materials, e.g. calcium nitrate, inorganic oxidizing salts, metals, etc. are then blended into the liquid mixtures and stirred until a uniform mixture is formed. The thickening agent, preferably dispersed in a dispersing agent, e.g. particulate salts or a water soluble liquid in which the polymer does not swell or swells very slowly, e.g. propylene glycol, is then blended in and the composition stirred until the viscosity becomes sufficient to hold the particulate constituents in suspension.
These compositions are unique in that they are more sensitive to detonation at low temperatures, maintain better fluidity at low temperatures, and can be detonated at higher densities at low temperatures than similar explosives which contain ammonium nitrate as the major inorganic oxidizing salt or calcium nitrate in lesser amounts.
The following examples will facilitate a more complete understanding of the present invention.
In the following examples a thin walled cylindrical polyethylene container about 1-7/8 inches in diameter and having a volume capacity of about 167 cc was filled with a test composition having a known density and temperature. The filled container was centered on a cylindrical steel driving plate about 4 inches in diameter and 5/8 inch thick (except as otherwise noted herein). The driving plate in turn was centered on the top of a 1-1/2 inch diameter by 3 inch long cylindrical cast lead block. The lead bock was placed on top of a 6 inch diameter by 1-1/2 inch thick cylindrical steel base plate which was placed on the ground. A detonator and high explosive booster charge was placed on top of the polyethylene container and the test composition detonated. The decrease in the height of the lead block was then measured.
EXAMPLE 1
26 compositions (Table I) were prepared containing in different proportions either formamide, ethylene glycol, or 50/50 weight ratio formamide/ethylene glycol mixture as the water soluble organic fuel, ammonium nitrate, fertilizer grade calcium nitrate and water. Each of these compositions was tested in the standard lead block detonation test, as previously defined, employing a 37 gram 50/50 pentolite booster (a cast mixture of equal parts of pentaerythritol tetranitrate and trinitrotoluene) and a No. 6 blasting cap as a detonator. The densities of the compositions were controlled by the addition of plastic microballoons which had a bulk density of about 0.03 gm/cc.
The samples to be tested were prepared by blending the water, fuel, plastic balloons and ground NH 4 NO 3 and Ca(NO 3 ) 2 with stirring for from 6 to 8 hours. The plastic balloons were added in an amount to provide the density desired in each test. About 1.5 parts by weight (per 100 parts of total mix) of carboxymethyl hydroxyethyl cellulose gelling agent was blended with about 3 parts by weight of propylene glycol and this blended into the slurry. The thickening agent and propylene glycol which were added are characteristic of water soluble organic fuels which can be employed in the present invention. The amount of such additional fuel was taken into consideration when determining the scope of the present invention as defined herein. The compositions were allowed to thicken to a rubbery consistency and then placed in the lead block containers.
An attempt was first made to detonate each composition at a temperature of 45°F. If the lead block was not deformed more than about 0.5 inch at that temperature a like composition was then usually tested at 60°F. If, however, the lead block was deformed more than about 0.5 inch at 45°F, a like composition was then tested at 32°F and if a deformation occurred there, a like composition was then tested at 10°F. The 0.5 inch deformation was an arbitrarily chosen cut off point based on previous observations that when a composition failed to give such a deformation it also usually failed at a lower temperature. Six series of tests were run; employing 26 different base compositions. The Series differed from each other first, in that in Series 1, 2 and 3 formamide was employed as the fuel and in Series 4, 5 and 6 ethylene glycol was employed as the fuel. Secondly, Series 2, and 3, 5 and 6 differed from Series 1 and 4 in that an additional amount of water above that present as hydration of the calcium nitrate was added to the compositions (Series 2 and 5, 5 percent additive H 2 O, and Series 3 and 5, 10 percent additive H 2 O).
Table I shows the constituents contained in base compositions Nos. 1-26 as percent by weight. In each series fertilizer grade calcium nitrate prills (CNF) were employed. A chemical analysis of CNF showed ≉4.5% ammonium nitrate, .about.14.4% water, .about.80.5% calcium nitrate with the balance being inert.
Tables II - VII show the results of the lead block tests in Series 1-6 as defined above. ΔH represents the deformation (inches of the lead block for each shot. X represents the lead block deformation divided by the density of the composition tested. This factor allows for the comparison of ΔH valves where the compositions being compared did not have equal densities, since for fully propagating explosives the deformation for like volumes of explosive is proportional to the densities of the explosives.
TABLE I ______________________________________ Basic Compositions Tested, as Percent by Weight Water Soluble Composition Organic No. Fuel NH 4 NO 3 CNF ______________________________________ 1 35 50 15 2 35 40 25 3 35 30 35 4 35 20 45 5 35 10 55 6 35 0 65 7 27 49 24 8 27 39 34 9 27 29 44 10 27 19 54 11 27 9 64 12 27 0 73 13 19 58 23 14 19 48 33 15 19 38 43 16 19 28 53 17 19 18 63 18 19 8 73 19 19 0 81 20 10 60 30 21 10 50 40 22 10 40 50 23 10 30 60 24 10 20 70 25 10 10 80 26 10 0 90 ______________________________________
TABLE II ____________________________________________________________
______________ Series No. 1, Formamide Fuel Base Composition 10°F 32°F 45°F 60°F No. ΔH Density X ΔH Density X ΔH Density X ΔH Density X ____________________________________________________________
______________ 1 0 1.12 0 0 1.13 0 2 0 1.16 0 0 1.16 0 3 0 1.14 0 0 1.14 0 4 0 1.15 0 .14 1.13 .123 5 0 1.19 0 .98 1.19 .823 6 0 1.23 0 0 1.25 0 7 0 1.20 0 0 1.20 0 8 0 1.18 0 0 1.18 0 9 0 1.22 0 .79 1.22 .647 9A .11 1.17 .094 10 .61 1.18 .52 .85 1.20 .708 1.08 1.19 .907 11 .73 1.25 .58 .85 1.21 .702 .95 1.25 .759 12 0 1.22 0 .72 1.25 .575 .86 1.23 .699 13 0 1.16 0 0 1.17 0 14 0 1.18 0 .83 1.17 .709 14A 0 1.17 0 15 .55 1.19 .462 .86 1.20 .716 16 .52 1.24 .42 .83 1.27 .653 .94 1.23 .764 17 .40 1.27 .32 .48 1.27 .377 .77 1.27 .606 18 .35 1.29 .271 .73 1.27 .574 19 .31 1.24 .250 .48 1.24 .387 20 .64 1.17 .54 .76 1.16 .655 .79 1.15 .686 21 .66 1.17 .564 .78 1.16 .672 21A .74 1.17 .631 22 .08 1.26 .063 .65 1.21 .537 22A .18 1.23 .145 23 0 1.23 0 .58 1.24 .467 23A 0 1.23 0 24 0 1.24 0 0 1.26 0 25 .43 1.26 .341 .54 1.23 .439 25A .47 1.26 .373 26 0 1.46 0 0 1.47 0 ____________________________________________________________
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TABLE III ____________________________________________________________
______________ Series No. 2 - Formamide, 5% by wt Additional H 2 O Base Composition 10°F 32°F 45°F 60°F No. ΔH Density X ΔH Density X ΔH Density X ΔH Density X ____________________________________________________________
______________ 1 0 1.13 0 2 0 1.15 0 3 0 1.17 0 4 0 1.16 0 5 0 1.21 0 6 0 1.20 0 7 0 1.15 0 8 0 1.16 0 9 .03 1.17 .025 .92 1.17 .79 10 0 1.24 0 .90 1.24 .73 .97 1.23 .79 11 .54 1.18 .46 .88 1.18 .75 .85 1.17 .73 12 0 1.20 0 .31 1.19 .26 .75 1.19 .63 13 0 1.22 0 14 0 1.22 0 .81 1.21 .67 15 0 1.20 0 .48 1.22 .39 .75 1.22 .62 16 0 1.22 0 .87 1.22 .71 .86 1.22 .71 17 .51 1.26 .40 .75 1.27 .61 .82 1.28 .64 18 .20 1.30 .15 19 .23 1.25 .18 .33 1.26 .26 20 0 1.22 .72 1.22 .59 21 .58 1.22 .49 .78 1.23 .63 21A .60 1.22 .48 22 0 1.28 0 23 0 1.25 0 .42 1.23 .34 24 0 1.29 0 25 0 1.27 0 0 1.28 0 25A 0 1.28 0 26 0 1.32 0 ____________________________________________________________
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TABLE IV ____________________________________________________________
______________ Series No. 3 - Formamide, 10% Additional H 2 O Base Composition 10°F 32°F 45°F 60°F No. ΔH Density X ΔH Density X ΔH Density X ΔH Density X ____________________________________________________________
______________ 1 0 1.13 0 2 0 1.12 0 3 0 1.17 0 3A .07 1.19 .06 4 0 1.17 0 5 0 1.19 0 6 0 1.20 0 7 0 1.15 0 8 0 1.19 0 9 0 1.17 0 .89 1.18 .75 10 0 1.19 0 .83 1.20 .69 .83 1.20 .69 11 0 1.22 0 .21 1.24 .17 .79 1.24 .64 12 0 1.23 0 13 0 1.20 0 14 0 1.26 0 0 1.26 0 15 0 1.17 0 .82 1.18 .69 0 1.26 0 16 0 1.22 0 .92 1.24 .74 .97 1.24 .78 17 .20 1.22 .16 .73 1.24 .59 .82 1.23 .67 18 .08 1.27 .06 .13 1.27 .10 19 0 1.28 0 0 1.28 0 20 0 1.25 0 .13 1.22 .11 .65 1.22 .53 21 .08 1.26 .06 .63 1.24 .51 22 0 1.20 0 .38 1.20 .32 23 0 1.21 0 0 1.21 0 24 0 1.27 0 0 1.27 0 25 0 1.23 0 0 1.23 0 26 0 1.29 0 ____________________________________________________________
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TABLE V ____________________________________________________________
______________ Series No. 4 - Ethylene Glycol Fuel Base Composition 10°F 32°F 45°F 60°F No. ΔH Density X ΔH Density X ΔH Density X ΔH Density X ____________________________________________________________
______________ 1 0 1.10 0 0 1.09 0 2 0 1.16 0 0 1.15 0 3 0 1.12 0 0 1.14 0 4 0 1.12 0 0 1.11 0 5 0 1.08 0 0 1.22 0 6 0 1.15 0 0 1.12 0 7 0 1.14 0 0 1.15 0 8 0 1.15 0 0 1.14 0 9 0 1.15 0 0 1.17 0 10 .04 1.15 .035 .70 1.17 .60 11 .41 1.14 .36 .79 1.13 .70 .88 1.13 .78 12 Not Run 13 0 1.15 0 0 1.13 0 14 0 1.17 0 .94 1.19 .79 .70 1.17 .60 15 .66 1.17 .56 1.01 1.15 .88 .86 1.13 .76 16 0 1.18 0 .90 1.18 .76 .88 1.17 .75 17 .64 1.19 .54 .87 1.19 .73 1.07 1.17 .91 18 0 1.23 0 .75 1.25 .60 .87 1.24 .70 19 Not Run 20 Not Run 21 Not Run 22 .57 1.15 .50 .74 1.16 .64 .83 1.15 .72 23 Not Run 24 Not Run 25 Not Run 26 0 1.29 0 ____________________________________________________________
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TABLE VI ____________________________________________________________
______________ Series No. 5 - Ethylene Glycol - 5% Additional H 2 O Base Composition 10°F 32°F 45°F 60°F No. ΔH Density X ΔH Density X ΔH Density X ΔH Density X ____________________________________________________________
______________ 1 0 1.07 0 2 0 1.15 0 3 0 1.0 0 4 0 1.15 0 5 0 1.17 0 6 0 1.18 0 7 0 1.20 0 8 0 1.21 0 9 0 1.16 0 10 0 1.24 0 11 .22 1.19 .19 .63 1.18 .53 .98 1.18 .83 12 .71 1.22 .58 13 0 1.17 0 14 0 1.17 0 15 0 1.18 0 0 1.17 0 .31 1.18 .26 16 .92 1.17 .79 1.01 1.17 .86 17 0 1.19 .2 .94 1.31 .72 .98 1.30 .75 18 .50 1.22 .41 .85 1.18 .72 19 0 1.26 0 .83 1.25 .66 20 0 1.15 0 .79 1.13 .70 .83 1.15 .72 21 0 1.16 0 0 1.15 0 22 0 1.23 0 1.04 1.14 .91 .88 1.24 .71 23 0 1.49 0 0 1.50 0 24 0 1.48 0 0 1.50 0 25 0 1.29 0 0 1.28 0 26 0 1.29 0 ____________________________________________________________
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TABLE VII ____________________________________________________________
______________ Series No. 6 - Ethylene Glycol - 10% Additional H 2 O Base Composition 10°F 32°F 45°F 60°F No. ΔH Density X ΔH Density X ΔH Density X ΔH Density X ____________________________________________________________
______________ 1 0 1.11 0 2 0 1.11 0 3 0 1.10 0 4 0 1.15 0 5 0 1.15 0 6 0 1.25 0 7 0 1.16 0 8 0 1.15 0 9 0 1.18 0 10 0 1.18 0 11 0 1.27 0 12 0 1.26 0 13 0 1.18 0 14 0 1.16 0 15 0 1.23 0 0 1.23 0 .74 1.23 .60 16 0 1.26 0 1.01 1.26 .80 .94 1.26 .746 17 .32 1.25 .26 .85 1.28 .664 18 .08 1.21 .06 .84 1.19 .71 19 .75 1.22 .62 20 .09 1.20 .075 .31 1.22 .25 21 .89 1.20 .74 22 0 1.23 0 .98 1.24 .79 .96 1.23 .78 23 .67 1.22 .55 24 0 1.32 0 25 0 1.26 0 .13 1.26 .10 26 0 1.29 0 ____________________________________________________________
______________
As demonstrated by this series of tests many of the compositions exhibited excellent sensitivity and energy as evidenced by the deformation of the lead block even at temperatures as low as 10°F. This is even more significant when it is noted that the compositions contained no auxiliary sensitizers and/or fuels, e.g., particulate metals, self-explosives and the like. The performance of these compositions and some of the poorer performing compositions, as to power and sensitivity, can be improved by the addition of such auxiliary materials as demonstrated in some of the following examples. However, these tests demonstrate the unique improvement offered by the novel composition because in many instances such costly and/or dangerous additives were unnecessary to obtain powderful explosives.
EXAMPLE 2
In this example certain compositions were tested in a standard underwater and a different lead block test than previously defined herein at normal and low temperatures. In the underwater tests the composition to be tested was placed in a two gallon pail along with a one-third pound high density booster charge. The pail was sealed with a lid through which the detonating cord extended. Water resistance was assured by a gasket sealing assembly at the opening where the detonating cord came through the lid. In the testing, the detonating cord was connected to an initiator and firing line and the pail was suspended in a body of water at about half the depth of a lake (pail placed at about 42.5 feet beneath the surface of the water). The composition was exploded and the resulting pressure profile from the explosion was converted into electrical impulses by a piezoelectric gauge suspended in the water at the same level a known horizontal distance from the explosive. The electrical impulses were recorded and converted to the corresponding pressures and from this, peak pressure, shock energy, bubble energy and the total energy of the explosive was calculated by methods described in "Underwater Explosives", R. H. Cole, Princeton University Press (1948). In this example and Table VIII, peak pressure is designated as "PK", the shock energy as "ESN", the bubble energy as "Y", and the total energy as "ET".
The results of testing eight compositions in the underwater test and procedure are set forth in the following Table VIII. The compositions listed in shot Nos. 4-8 fall within the scope of the present invention. Shot Nos. 1 and 2 demonstrate the results obtained where ammonium nitrate was the sole oxidizing salt. The composition in shot No. 3 is similar to a commercially available unmetallized slurry explosive formulation. As demonstrated by these tests certain of the compositions of the present invention showed superior energies over the other compositions tested and all showed superior peak pressures.
To demonstrate the unique low temperature sensitivity properties of the present invention compositions corresponding to those in shot Nos. 3 and 8 were tested in a standard lead block deformation test as described hereinbefore. The composition of shot No. 8 detonated at 10°F, at a density of 1.25 grams/cc with a deformation of 0.73 inch while the composition of shot No. 3 failed to detonate in the lead block test even at a lower density of 0.93 gm/cc, at 73°F. The lower density and higher temperature favor detonation of explosives.
This data shows the superior sensitivity properties of the present composition, for low temperature use.
TABLE VIII ____________________________________________________________
______________ Pts. by Wt. Constituents As Shot Wt. No CNF AN 1 SN 2 NH 3 H 2 O F 3 EG 4 PG 5 Sugar Gum Lbs ESN Y ET PK ____________________________________________________________
______________ 1 67.8 8.14 11.6 10.5 1.96 22.1 .015 .000 .015 1367 2 73.9 13 11.4 1.7 23.09 .010 .011 .021 1380 3 69 8 7 10 1 4 1 .about.19 .265 .338 .603 2018 4 60.13 17.12 4.75 18 22.1 .284 .285 .574 2408.8 5 63 18 19 21.4 .317 .303 .620 2406.7 6 57.3 16.3 9.1 16.3 20.7 .350 .340 .690 2575.5 7 57.3 16.3 9.1 16.3 21.5 .319 .293 .612 2417.4 8 64 9 27 21.2 .328 .316 .644 2651.5 ____________________________________________________________
______________ 1 AN -- ammonium nitrate 2 SN -- sodium nitrate 3 F -- formamide 4 EG -- ethylene glycol 5 PG -- propylene glycol pg,33
EXAMPLE 3
As a further example of the superior low temperature sensitivity of compositions falling within the scope of the present invention several compositions were prepared containing CNF, formamide, water and ammonium nitrate. Five compositions were prepared containing the constituents as parts by weight as set forth in the following Table IX. The compositions were tested in the previously defined standard lead block test at 45°F, the primer consisting of a 37 gram 50/50 pentolite booster. The results of the tests are also tabulated in the Table IX. Each composition varied from composition of test No. 1 in that a quantity of calcium nitrate was replaced by a like weight of ammonium nitrate. Five percent by weight of water was also employed over that present in the CNF. The uniqueness of the compositions containing greater proportions of calcium nitrate at lower temperatures is shown by the fact that in shots 3-5, containing at least 55 or more parts by weight ammonium nitrate, no detectable lead block deformations were produced even though the oxygen balance appeared to be more favorable at high ammonium nitrate levels.
TABLE IX ______________________________________ Shot Specific Weight Temp No Gravity G.M.S. °F ΔH Form CAN AN H 2 O ______________________________________ 1 1.17 191 45 .96 17 58 25 5 2 1.15 184 45 1.03 17 43 40 5 3 1.16 188 45 0 17 28 55 5 4 1.15 186 45 0 17 13 70 5 5 1.16 188 45 0 17 0 83 5 ______________________________________
EXAMPLE 4
In this example various compositions were prepared containing CNF, formamide, and water in amounts within the scope of the present invention. To these compositions were added various inorganic salts, while maintaining the ratio of CNF to formamide approximately the same. The compositions were tested at a temperature of about 70°F in the previously defined standard lead block test and ΔH and X, as defined hereinbefore, tabulated for each. The base compositions (Mixes A-D), as parts by weight, the additives (parts by weight) and results of the lead block tests are set forth in the following Tables X - XIII.
TABLE X ______________________________________ Mix A Base Comp (Mix A) (28 parts by wt. Formamide (57 parts by wt. CNF (15 parts by wt. NH 4 NO 3 Additive Parts/Wt. Density Δ H X ______________________________________ Control 1.14 1.06 0.93 NaNO 3 5.25 1.12 0.93 0.83 NaNO 3 11.1 1.20 0.99 0.83 NaNO 3 17.7 1.10 0.91 0.83 NaNO 3 25.0 1.10 0.92 0.83 NaNO 3 42.8 1.05 0.85 0.81 NaNO 3 53.8 1.06 0.87 0.82 CaSO 4 5.25 1.03 0.77 0.75 CaSO 4 11.1 1.05 0.77 0.74 ______________________________________
TABLE XI ______________________________________ Mix B Mix B (30 parts by wt. Formamide (70 parts by wt. CNF Additive Parts/Wt. Density Δ H X ______________________________________ Control 1.12 0.82 0.73 NaNO 3 5.25 1.12 0.82 0.73 NaNO 3 11.1 1.18 0.71 0.60 NaNO 3 17.7 1.22 0.91 0.75 NaNO 3 25.0 1.20 0.85 0.71 NaNO 3 33.4 1.13 0.66 0.58 NaNO 3 42.8 1.12 0.47 0.42 NaNO 3 53.8 1.08 0.16 0.148 NH 4 NO 3 11.1 1.15 1.08 0.94 NH 4 NO 3 25.0 1.11 1.16 1.05 NH 4 NO 3 42.8 1.10 1.16 1.05 NH 4 NO 3 66.7 1.11 1.05 0.95 NH 4 NO 3 100.00 1.10 1.07 0.97 NH 4 NO 3 150.00 1.08 1.05 0.97 Ba(NO 3 ) 2 11.1 1.11 1.02 0.92 Ba(NO 3 ) 2 25.0 1.16 1.04 0.90 Ba(NO 3 ) 2 42.8 1.22 0.87 0.71 ______________________________________
TABLE XII ______________________________________ Mix C Mix C (25 parts by wt. Formamide (75 parts by wt. CNF Additive Parts/Wt. Density Δ H X ______________________________________ Control 1.18 0.91 0.77 NH 4 NO 3 11.1 1.11 0.88 0.79 NH 4 NO 3 25 1.08 0.89 0.82 NH 4 NO 3 42.8 1.07 0.90 0.84 NH 4 NO 3 66.7 1.04 0.85 0.82 NH 4 NO 3 100 1.07 0.85 0.79 NH 4 NO 3 150 1.05 0.93 0.89 NaNO 3 11.1 1.11 0.74 0.67 NaNO 3 25 1.14 0.50 0.44 NaNO 3 42.8 1.15 0.15 0.13 NaNO 3 66.7 1.21 0.03 0.025 NaNO 3 100 1.22 0.02 0.025 NaNO 3 150 1.23 0.02 0.016 Ba(NO 3 ) 2 11.1 1.07 0.80 0.75 Ba(NO 3 ) 2 25.0 1.14 0.80 0.70 Ba(NO 3 ) 2 42.8 1.19 0.79 0.66 ______________________________________
TABLE XIII ______________________________________ Mix D Mix D (35 parts by wt. Formamide (65 parts by wt. CNF Additive Parts/Wt. Density Δ H X ______________________________________ Control 1.07 0.10 0.093 NH 4 NO 3 11.1 1.13 0.92 0.81 NH 4 NO 3 25.0 1.15 0.96 0.83 NH 4 NO 3 42.8 1.14 1.06 0.93 NH 4 NO 3 53.8 1.14 0.98 0.86 NH 4 NO 3 100 1.18 0.73 0.62 NH 4 NO 3 150.0 1.16 0.71 0.61 NaNO 3 11.1 1.06 0.11 0.10 NaNO 3 25.0 1.04 0.07 0.067 NaNO 3 42.8 1.14 0.04 0.035 NaNO 3 53.8 1.16 0.03 0.025 NaNO 3 100 1.21 0.03 0.025 Ba(NO 3 ) 2 11.1 1.04 0.02 0.019 Ba(NO 3 ) 2 25.0 1.07 0.04 0.037 Ba(NO 3 ) 2 42.8 1.11 0.05 0.045 Ba(NO 3 ) 2 53.8 1.09 0.02 0.018 Ba(NO 3 ) 2 100 1.11 0.05 0.045 ______________________________________
EXAMPLE 5
In this example various additives and combinations of additives were added to a base CNF mixture. The compositions were tested in a standard lead block test at densities ranging from about 1.00 gm/cc to about 1.24 gm/cc. The constituents in these various compositions, and lead block data are set forth in the following Tables XIV and XV.
TABLE XIV ____________________________________________________________
______________ Composition Number Parts by Weight Constituents 1 2 3 4 5 6 7 8 9 10 ____________________________________________________________
______________ CNF 40 40 40 40 40 40 40 40 40 57 Ethylene Glycol 10 10 10 10 10 10 10 10 Formamide 28 NH 4 NO 3 10 5 5 5 5 15 Urea 10 KNO 3 5 10 NaNO 3 5 NaSO 4 5 10 (NH 2 ) 2 . SO 4 5 10 H 2 O 5 5 5 5 5 5 5 5 Al 5.25 ΔH 0.02 0.73 0.06 0.88 0.13 0.80 0.44 0.78 0.12 0.92 Density 1.14 1.14 1.19 1.14 1.24 1.18 1.21 1.14 1.16 1.00 X 0.017 0.64 0.05 0.77 0.11 0.68 0.36 0.68 0.10 0.92 ____________________________________________________________
______________
TABLE XV ____________________________________________________________
______________ Composition No. - Parts by Wt. Constituents 1 2 3 4 5 6 7 8 9 10 ____________________________________________________________
______________ CNF 57 57 57 57 57 57 57 57 57 57 Formamide 28 28 28 28 28 28 28 28 28 28 NH 4 NO 3 15 15 15 15 15 15 15 15 15 NaNO 3 MgSO 4 11.1 25.0 MgO 11.1 CaSO 4 5.25 11.1 Ferrophosphorous 11.1 15 Sulfur 11.1 11.1 Starch 11.1 Sand 11.1 Wood Fibers Mg Al (flake) ΔH 0.65 0.04 0.79 0.77 0.71 0.70 0.77 0.77 0.07 0.02 Density 1.02 1.12 1.09 1.12 1.09 1.04 1.03 1.05 1.12 1.19 X 0.64 0.036 0.73 0.69 0.65 0.67 0.75 0.73 0.06 0.017 Constituents 11 12 13 14 15 16 17 18 ____________________________________________________________
______________ CNF 57 57 57 57 57 57 70 70 Formamide 28 28 28 28 28 28 30 30 NH 4 NO 3 15 15 15 15 NaNO 3 15 15 MgSO 4 11.1 MgO CaSO 4 Ferrophosphorous Sulfur Starch Sand Wood Fibers 5.25 Mg 11.1 Al (flake) 11.1 11.1 ΔH 0.92 0.89 0.87 0.31 0.86 1.06 0.65 Density 1.15 1.22 1.19 1.07 1.16 1.14 1.10 X 0.80 0.73 0.73 0.29 0.74 0.93 0.59 ____________________________________________________________
______________
EXAMPLE 6
In this example different water soluble organic fuels were employed while keeping the weight ratio of CNF, fuel, water and ammonium nitrate approximately equal. The compositions were tested in the aforementioned lead block test at about 70°F. The results of these tests were set forth in the following Table XVI. The results of these tests demonstrate the application of different water soluble organic fuels and mixtures of such fuels in the preparation of compositions within the scope of the present invention.
TABLE XVI ____________________________________________________________
______________ Parts by Weight Temp. Booster Density Fuel Fuel CNF AN H 2 O F° gms/cc gms/cc Δ H X ____________________________________________________________
______________ Propylene Glycol 15.4 61.6 15.4 7.7 70 37 gms 1.45 0.00 0.00 70 1.35 0.05 0.037 70 1.21 0.37 0.31 70 1.15 0.78 0.69 70 1.08 0.75 0.69 Sorbitol 15.8 60.0 15.0 9.0 70 1.47 0.02 0.014 1.38 0.03 0.02 1.23 0.66 0.54 1.16 0.80 0.069 1.09 0.83 0.76 Ethylene Glycol 7.7 Propylene Glycol 7.7 61.6 15.4 7.7 70 1.46 0.02 0.014 1.38 0.04 0.029 1.26 0.60 0.48 1.20 0.87 0.73 1.11 0.90 0.81 Parts by Weight Temp. Booster Density Fuel Fuel CNF AN H 2 O F° gms/cc gms/cc W H X ____________________________________________________________
______________ Ethylene Glycol 7.7 Glycerine 7.7 61.6 15.4 7.7 1.45 0.02 0.014 1.34 0.06 0.045 1.23 0.66 0.54 1.16 0.88 0.76 1.08 0.92 0.85 Ethylene Glycol 7.7 Tripropylene Glycol Methyl-ether 7.7 61.6 15.4 7.7 1.42 0.02 0.014 1.37 0.08 0.06 1.24 0.73 0.59 1.16 1.10 0.95 1.07 0.90 0.84 Parts by Weight Temp Booster Density Fuel Fuel CNF AN H 2 O F° gms/cc gms/cc Δ H X ____________________________________________________________
______________ Formamide 7.7 Ethylene Glycol 7.7 61.6 15.4 7.7 70 40 gms 1.45 0.01 0.007 1.35 0.02 0.015 1.24 0.14 0.12 1.14 0.74 0.65 1.07 0.79 0.74 Ethylene Glycol 15.4 61.6 15.4 7.7 1.45 0.01 0.007 1.36 0.02 0.015 1.26 0.11 0.09 1.18 0.86 0.73 1.11 0.96 0.87 ____________________________________________________________
______________
EXAMPLE 7
Several compositions containing the constituents listed below were tested in the aforementioned lead block test at a temperature of about 70°F in the manner as defined in the previous examples. Metal was added to some of these compositions and also different water soluble organic fuels were employed. The compositions are listed in the following Table XVII as percent by weight:
TABLE XVII ______________________________________ Composition Constituent A B C D E ______________________________________ Ethylene Glycol 14.1 12.2 16.4 -- -- Formamide -- -- -- -- 14.14 Methanol -- -- -- 14.14 -- Ca(NO 3 ) 2 39.1 33.86 45.6 39.3 39.3 H 2 O 17.2 14.94 20.0 17.3 17.3 Ammonium Nitrate 14.1 12.2 16.4 14.14 14.14 Particulate Aluminum 14.1 24.4 -- 14.14 14.14 Thickener 1.4 2.4 1.6 0.98 0.98 ______________________________________
Ca(NO 3 ) 2 . 4H 2 O was employed and the amount of water in the composition takes into account the 4 waters of hydration.
The results of the lead block detonation tests are tabulated in the following Table XVIII.
As shown by these data the employment of particulate aluminum greatly increases the sensitivity and power of the explosive composition as indicated by the greater deformations caused by compositions A, B, D and E. With about 24 percent by weight of metal, composition B, there was substantial deformation of the lead block even at a density of about 1.5 gm/cc.
TABLE XVIII ______________________________________ Density Composition (gm/cc) ΔH Inches X ______________________________________ A 1.41 0.07 .05 1.38 0.05 .04 1.30 0.79 .61 1.18 1.24 1.05 1.11 1.07 .96 1.03 1.07 1.04 B 1.50 0.28 .19 1.38 0.69 .50 1.23 1.11 .90 C 1.42 0.02 .014 1.27 0.12 .094 1.16 0.98 .85 D 1.36 0.09 .07 1.26 0.53 .42 1.16 1.07 .92 1.08 1.05 .97 1.00 1.16 1.16 E 1.32 0.58 .44 1.20 1.05 .88 1.13 1.24 1.10 1.07 1.06 .99 0.97 1.00 1.03 ______________________________________
To further show the effect of metal two compositions were tested at approximately 32°-33°F in a standard lead block deformation test. The two compositions were identical except that one composition contained 10 parts by weight of particulate aluminum. The compositions, and results of the tests are set forth in the following Table XIX and graphically illustrated in FIG. 5.
As evidenced by this data the addition of particulate metal, as would be expected, increased the sensitivity and strength of the composition.
TABLE XIX ____________________________________________________________
______________ Composition A Parts by Wt. Shot Specific Weight Temp Ethylene Ca(NO 3 ) 2 . No. Gravity Grams °F Δ H X Glycol 4H 2 O Al NH 4 NO 3 Thickener ____________________________________________________________
______________ 1 1.37 223.0 32 0.06 .044 10 40 10 10 1 2 1.30 210.5 32 0.14 .11 10 40 10 10 1 3 1.20 195.5 32 0.93 .78 10 40 10 10 1 4 1.12 182.0 32 1.07 .96 10 40 10 10 1 5 1.04 169.5 32 1.03 .99 10 40 10 10 1 Compositions B Ethylene Glycol Ca(NO 3 ) 2 . 4H 2 O NH 4 NO 3 1 1.31 212.5 33 0.02 .015 10 40 10 2 1.20 195.5 33 0.09 .075 10 40 10 3 1.11 180.0 33 0.82 .74 10 40 10 4 1.01 164.1 33 0.80 .79 10 40 10 5 0.91 147.5 33 0.74 .81 10 40 10 ____________________________________________________________
______________
EXAMPLE 8
Various explosive properties of the following compositions were compared.
______________________________________ Composition No. Constituent Parts by Weight 1 2 3 4 ______________________________________ CNF 57 NH 4 NO 3 15 62.75 70.5 46.75 NaNO 3 8 8.0 8 H 2 O 12 7.5 15 Formamide 28 4 13 4 Ethylene Glycol 3 1 2 Al (particulate) 5.25 9 23 Thickening Agent 1 1 1 Other 0.25 0.25 ______________________________________
Composition No. 1 falls within the scope of the present invention while compositions 2-4 consist of formulations of commercially available explosives.
The tests consisted of (1) a plate dent test to determine average detonation velocity of a confined explosive and dent pressure; (2) a detonation velocity test of unconfined explosive and (3) a cone test to determine minimum critical diameter.
In the plate dent test the average detonation velocity of a confined explosive is determined. Both the detonation velocity and the plate dent relate to the peak pressure or brisance of the explosive. In the present example a 2 inch inside diameter extra heavy open ended steel pipe 20 inches long was filled with an explosive composition to be tested. The pipe contained two ports through the wall thereof a known distance apart. Contactors were inserted through these ports and were employed to determine the velocity of detonation. One end of the pipe was centered on a cylindrical steel plate 3 inches in diameter and 4 inches thick. A 37 gram high pressure primer was centered on the opposite end of the pipe in contact with the explosive mixture. The primer was detonated with an electric blasting cap. The detonation velocity was determined upon detonation by suitable timing instrumentation known to those skilled in the art which measured the time for the detonation wave to progress from the first to second contactors. The plate dent pressure is determined from calculations known in the art based upon the dent produced by the explosive in the steel base plate.
In the second test the detonation velocity of unconfined explosive was determined. The unconfined detonation velocity test was determined by placing an explosive to be tested in a cardboard tube 16 inches long and of constant diameter over the length thereof. The diameter is any diameter which is greater than the critical diameter of the explosive being tested. The velocity was measured by employing contactors in the same manner as described for the plate dent test. A 37 gram high pressure booster was placed at one end of the tube in contact with the explosive and the booster armed and detonated with an electric blasting cap.
The third test consisted of a cone test to determine the minimum diameter column of explosive which will sustain propagation. In the cone test hollow tapered tubes constructed of cardboard 24 inches long were filled with the explosive to be tested. The explosives to be tested were first tested in a tube which evenly tapered from 4 to 3 inches in diameter. If the entire column of explosive propagated a like composition was then placed in a tube which tapered evenly from 3 inches to 2 inches in diameter. The explosive was always detonated from the larger end of the tube. After the detonation the diameter of any remains of the tube were measured at the position where the explosive appeared to fail to propagate.
The results of the tests are set forth in the following Table XX.
As shown by the data metallized compositions of the present invention show superior performance when compared to other metallized and unmetallized explosive compositions when tested at normal and low temperatures.
TABLE XX ______________________________________ Composition No. 1 2 3 4 Plate Dent Test ______________________________________ Density of explosive (gm/cc) 1.25 1.23 1.20 1.27 Detonation velocity (ft/sec) 16,866 15,372 Failed 13,866 Dent pressure (kbar)* 29 33 -- 26 Temperature (°F) 75 75 75 75 Unconfined Detonation Velocity Test ______________________________________ Diameter of tube (inches) 4 4 4 4 Temperature (°F) 75 75 75 75 Density of explosive (gm/cc) 1.25 1.25 1.20 1.27 Detonation velocity (ft/sec) 18,835 10,000 Failed Failed Cone Test ______________________________________ Temperature (°F) 75 75 Not Not Density of explosive (gm/cc) 1.20 1.21 Tested Tested Minimum diameter (inches) 1.5 31/2 ______________________________________ *kbar = 1 kilo bar equals 1000 bars equals 14,700 psi
As these tests show the composition of the present invention demonstrated superior detonation velocities and better sensitivity (better minimum diameter) than did the other two metallized compositions which contained greater amounts of metal.
EXAMPLE 9
Explosive compositions were prepared from base mixes comprising; Mix A, 30 percent formamide and 70 percent CNF; and Mix B, 28 percent formamide, 57 percent CNF and 15 percent NH 4 NO 3 . Plastic balloons were employed as a density control agent and carboxy methyl hydroxyethyl cellulose was employed as a thickener. Additional NH 4 NO 3 and particulate aluminum were premixed into some of these base mixes and they were tested in small diameter cardboard and metal tubes. The results, diameters, size of initiator and formulations are set forth in the following Table XXI.
All the compositions were shot at about 70°F. The boosters consisted of 50/50 pentolite in an amount as shown or a blasting cap.
TABLE XXI ____________________________________________________________
______________ Wt % Paint Booster Tube Type Result Wt % Wt % Wt % Grade Weight Diam. Length and Density Inches Mix A NH 4 NO 3 Al Al gms Inches Inches Thickness gm/cc Left ____________________________________________________________
______________ 90A 10 5 3/4 8 1/16 cardboard 1.05 0 95A 5 5 3/4 8 1/16 cardboard 1.17 0 98A 2 5 3/4 8 1/16 cardboard 1.30 4 98A 2 No.6 cap 1/2 8 1/8 steel 1.33 0 Wt % Mix B 50B 40 10 5 3/4 8 1/16 cardboard 1.17 4.5 50B 40 10 10 3/4 8 1/16 cardboard 1.17 4.5 50B 40 10 20 3/4 8 1/16 cardboard 1.17 4.5 50B 40 10 Engineers 1/2 8 1/8 steel 1.18 0 special 50B 40 10 No.6 cap 1/2 8 1/8 steel 1.18 0 50B 40 10 Engineers 1 8 1/8 steel 1.18 0 special 50B 40 10 No.6 cap 1 8 1/8 steel 1.18 0 ____________________________________________________________
______________
Fluidity Examples
In examples 10 to 12 data was obtained to show the plasticity properties of compositions falling within the scope of the present invention.
EXAMPLE 10
In this example an indication of the fluidity of a composition was determined by observing the proportion of a mixture occupied by undissolved solids when the system had reached equilibrium. This parameter was chosen since the fluidity (and pumpability) of slurry explosives decreases as volume occupied by the solids approaches the volume occupied by the total composition.
The ingredients were weighed into a clear, cylindrical plastic container. The mixture was then stirred for several hours at room temperature (≉75°F) and allowed to settle overnight. The height of solid layer (HS) and the total mixture height (HO) in the container were measured and the ratio obtained as: ##EQU1##
Data were obtained in this way for mixtures of fertilizer grade NH 4 NO 3 and CNF in ethylene glycol, formamide and 50/50 (by weight ratio) formamide-ethylene glycol fueled mixtures, each with 0, 5 and 10% by weight additional water. Methanol was also tested as a fuel for a 10% water level only. In the methanol tests, samples were stirred by hand 2 or 3 times daily for several days and then allowed to settle. They were not placed on mechanical stirrers due to possible evaporation loss. The methanol system was observed both at room (75°F) and 6°F temperatures.
The R H values for various compositions are listed in the following Tables XXII and XXIII. In Table XXIII percent by weight of CNF and NH 4 NO 3 are shown with methanol comprising the balance. The solubility results for the ethylene glycol-10% H 2 O compositions are illustrated in FIG. 6. In this diagram the solid and broken lines represent constant R H values of about 25 and 50 respectively for the different compositions tested. The points represent the composition tested and the numbers over the points represent the R H value (for that composition). These lines of approximately constant R H values were obtained by visual interpolation. They demonstrate that better fluidity properties are obtained at higher Ca(NO 3 ) 2 levels at even less liquid content than at the higher NH 4 NO 3 levels. The data obtained on the other fuel systems when plotted in this manner show similar fluidity characteristics.
TABLE XXII ____________________________________________________________
______________ R H = 100 × (HS/HO) Constituents Formamide* Ethylene Glycol* 50/50 Formamide/ Composition % % 0% Ethylene Glycol* No. NH 4 NO 3 CNF H 2 O 5% 10% 0% 5% 10% 0% 5% 10% ____________________________________________________________
______________ 1 50 15 34 17 0 60 41 33 54 36 9 2 40 25 26 9 0 64 35 24 45 25 4 3 30 35 10 0 0 71 38 8 28 11 0 4 20 45 0 0 0 68 39 13 17 0 0 5 10 55 0 0 0 75 49 33 23 0 0 6 0 65 0 0 0 100 78 42 42 0 0 7 49 24 48 42 10 85 57 33 63 42 77 8 39 34 34 18 1 93 57 21 51 29 10 9 29 44 20 0 0 100 53 15 46 5 0 (9) 18 0 0 100 49 14 49 5 0 10 19 54 0 0 0 100 53 26 42 0 0 (10) 0 0 0 100 58 20 49 0 0 11 9 64 0 0 0 100 62 35 41 0 0 12 0 73 0 0 0 100 70 45 15 12 0 13 58 23 73 50 32 100 66 48 90 61 43 14 48 33 53 35 22 100 74 35 75 45 24 15 38 43 25 17 4 100 61 22 79 25 11 16 28 53 2.5 0 0 100 63 11 77 22 0 17 18 63 11 0 0 100 71 27 68 40 0 18 8 73 42 3 0 100 65 34 100 22 0 (18) 35 75 0 100 75 39 100 30 0 19 0 81 42 38 0 100 85 44 100 46 9 20 60 30 85 58 44 100 100 56 100 75 50 21 50 40 76 34 22 100 56 38 100 57 32 22 40 50 77 25 7 100 67 27 100 44 11 23 30 60 52 2.5 0 100 38 28 100 45 7 (23) 60 5.1 0 100 72 36 100 50 0 24 20 70 85 23 2 100 55 31 100 59 24 25 10 80 100 45 24 100 67 39 100 68 36 26 0 90 100 86 55 100 100 63 100 100 55 ____________________________________________________________
______________ Note: Systems in parenthesis are duplicate tests *The fuel comprises the balance based on 100% by weight of NH 4 NO 3 , CNF and fuel and water is in addition to the base 3 component composition.
TABLE XXIII ______________________________________ Composition % by Wt. % by Wt. R H values at No. NH 4 NO 3 CNF Room Temp. ______________________________________ 1 45 26 29 2 38 33 18 3 30 41 6 4 22 48 0 5 15 56 0 6 8 63 0 7 9 71 2 8 53 25 43 9 46 32 31 10 38 40 19 11 31 47 6 12 23 55 2 13 16 62 0 14 8 70 4 15 1 77 13 16 60 25 56 17 53 32 42 18 45 40 28 19 38 47 15 20 30 55 4 21 23 62 3 22 15 70 9 23 8 77 21 24 0 85 34 25 67 25 67 26 60 32 57 27 52 40 41 28 45 47 25 29 37 55 9 30 30 62 2 31 22 70 9 32 15 77 50 33 7 85 50 34 0 92 63 ______________________________________
EXAMPLE 11
In this example a set of solubility data was obtained on a NH 4 NO 3 , CNF and formamide system in the same manner as described in the previous example. The data is summarized in FIGS. 7 to 9. In this example the mixes were allowed to equilibrate at .about.75°F and the presence of solids was noted. Then the mixes were cooled, first to 32°F and then to 10°F and the presence of solids was noted at each temperature level. 24 hours was the minimum time allowed for equilibration.
In FIG. 7 the dots represent the percent by weight of the 3 constituents in each test composition and in all the figures the solid curves represent approximately constant R H values of about 25 percent. FIG. 7 gives the change in solubility noted for the system containing no water except that originally in the CNF. FIG. 8 is similar data for the system containing 10% added H 2 O, and FIG. 9 is a composite of 10°F data showing the curves for 0, 5 and 10% added water.
It is significant to note that major shifts in the composition of the solid-liquid line occur with temperature at high formamide and high NH 4 NO 3 levels. At the minimum in the curve at about 20% NH 4 NO 3 -20% formamide-CNF there is relatively little shift of the equilibrium composition with temperature.
EXAMPLE 12
Eleven different base compositions plus 10 percent by weight additional water were formulated for each of 3 fuels, formamide, ethylene glycol and methanol, and placed into 2 quart (stacked 1 quart cylindrical cardboard containers about 3 inches in diameter) and cooled to 20°F. These samples were tested for fluidity by observing the relative ease with which one finger could be inserted into the mix with normal hand pressure.
Plasticity was reported as H if the mix was so hard that it could not be deformed appreciably with finger pressure. It was rated P if it was deformable plastic, similar to a very heavy grease or soft wax. An S rating indicates that the mix was very soft and required little or no force to deform it.
FIGS. 10 to 12 show the plasticity data obtained in this manner for the different compositions tested at 20°F. The letter corresponding to the plasticity is positioned on the diagram at the point corresponding to its fuel, --NH 4 NO 3 , CNF composition ratio.
From these data points, the regions of soft and plastic mixes are outlined and shaded to indicate those compositions having unique fluidity properties at lower temperatures.
It is noteworthy that the regions of soft and plastic formulations shown in FIGS. 10 to 12 correspond closely to the regions of room temperature solubility shown in FIGS. 7 to 9.
EXAMPLE 13
Certain compositions coming within the scope of the present invention were prepared containing the constituents set forth in the following Table XXIV. The minimum initiator required to detonate a 2 inch diameter column of the composition at 35°F was determined. Also the detonation velocity of each composition was determined by the Dautriche method. The compositions and results of these tests are set forth in the following Table XXIV.
TABLE XXIV ____________________________________________________________
______________ Compositions A B C D E F G ____________________________________________________________
______________ Density gm/cc 1.00 1.25 1.40 0.90 1.15 1.25 1.35 Energy, Kcal/gm 1 0.68 1.002 1.135 0.804 0.936 1.041 1.155 Velocity, Ft/sec 11,700 13,700 13,900 11,600 13,700 13,900 13,200 Ingredients (Percent by Wt.) Formamide 12.42 11.49 10.66 11.80 12.09 11.73 10.98 Ethylene Glycol 4.74 4.39 4.07 4.51 4.62 4.48 4.19 Ammonium Nitrate (AN) 22.02 18.36 16.29 21.36 18.16 17.03 15.74 Calcium Nitrate 2 45.54 42.12 39.10 43.25 44.33 43.03 40.24 Coarse Aluminum (≉ +325 mesh) -- 11.73 19.55 -- 5.87 9.74 15.64 Pigment Aluminum (≉ -325 mesh) -- -- -- 3.91 3.91 3.91 3.91 Water Added 9.46 7.82 6.87 9.21 7.64 7.11 6.59 Guar Gum 2.25 2.25 2.25 2.25 2.25 2.25 2.25 Wet Thermoplastic Micro-balloons 3 3.56 1.84 1.20 3.72 1.12 0.68 0.48 Formula Constants Formamide/Eth. Glycol Weight Ratio 2.62 2.62 2.62 2.62 2.62 2.62 2.62 CNF/AN Weight Ratio 2.07 2.29 2.40 2.02 2.44 2.53 2.56 Oxygen Balance % grams/100 grams +1.51 -9.44 - 16.73 -2.18 -7.59 -11.19 -16.72 Total Water % 18.96 15.52 13.64 18.49 15.13 14.07 12.99 Minimum Booster at 35°F 37 gm 4 37 gm >37 gm No. 6 cap No. 6 cap No. 6 37 ____________________________________________________________
______________ gm 1 Energy was determined by underwater technique as described in Cole "Underwater Explosions" (1948). 2 Fertilizer grade (CNF) 3 An aqueous slurry containing about 85 percent H 2 O and 15 percent of balloons. 4 Grams of composition C-4, plastic explosive containing .about.90% RDX and 10% inert binder.