US2976137A

US2976137A - Ammonium nitrate explosives

Info

Publication number: US2976137A
Application number: US819530A
Authority: US
Inventors: Leonard A Stengel
Original assignee: Commercial Solvents Corp
Current assignee: Commercial Solvents Corp
Priority date: 1959-06-04
Filing date: 1959-06-04
Publication date: 1961-03-21
Anticipated expiration: 1978-03-21

Description

AMMONIUM NITRATE EXPLOSIVES Leonard A. Stengel, Terre Haute, Ind., assignor to Cornmercial Solvents Corporation, New York, N.Y., a corporation of Maryland No Drawing. Filed June 4, 1959, tier. No. 819,530

7 Claims. (Cl. 52-44) My invention relates to new ammonium nitrate compositions suitable for use as explosives and for making explosives containing ammonium nitrate and an amino compound represented by the structural formula where R is selected from the group consisting of lower alkyl, lower hydroxyalkyl and C H NH and R is selected from the group consisting of hydrogen, lower alkyl and -C H NH and to processes for using same.

Ammonium nitrate has long been known to be flammable and explosive and these properties have been made use of extensively, ammonium nitrate being now widely used as an explosive although it possesses certain inherent disadvantages, such as low density, and relative insensitivity when used as an explosive.

While these low density ammonium nitrate explosives are satisfactory for certain situations involving relatively easy biasting, they cannot develop the detonation velocities and bore hole pressures needed in blasting hard rock difiicult to fracture. The ammonium nitrate-amino compositions of my invention, however are of relatively high density ranging from 1.0 to 1.5 and are sufficiently sensitive for practical application in blasting without any manufacturing steps or ingredients not readily, simply and safely performed and used at the site. High density ammonium nitrate mixtures of this range used in the past have either involved a sensitizer more sensitive and dangerous to handle than the ammonium nitrate and hence such mixtures were difficult to store, ship, handle and mix with other ingredients or they involved manufacturing steps diflicult to carry out in the field.

It is extremely dangerous to prepare ammonium nitrate explosives containing trinitrotoluene or other similar explosives outside of a permanent industrial explosives factory meeting all known safety requirements and operated by personnel experienced in the manufacture of explosives. Furthermore, the ammonium nitrate and carbonaceous material ordinarily used therewith must be thoroughly mixed and combined in equipment which is only found in an industrial plant for the manufacture of explosives. As large amounts of ammonium nitrate and sensitizers are always present in factory operations, there is the ever-present danger of disastrous explosions which may demolish the area surrounding the industrial plant for the production of explosives.

I have now discovered that combinations of ammonium 2,976,132 Patented Mar. 21, 196i nitrate with varying amounts of amino compounds represented by the structural formula Hat where R is selected from the group consisting of lower alkyl, lower hydroxyalkyl, and C H NH and R is selected from the group consisting of hydrogen, lower alkyl and C H NH ranging from 2 to 50% by weight, based on the weight of the mixture, can be advantageously employed either as explosives or in the preparation of explosives. Compositions containing the amino compounds hereinabove specified in amounts ranging from 2-14%, and preferably in amounts ranging from 6-8% by weight, based on the weight of the mixture, constitute effective explosives and are generally more effective as such than other previously known ammonium nitrate explosives. As the amount of said amino compounds is increased beyond the preferred ranges above specified the sensitivity of the compositions as explosives decreases. This property permits the formulation of ammonium nitrate-amino compound compositions of sufficiently reduced sensitivity to allow their transportation with safety. I prefer, therefore, to produce and ship compositions in solution form consisting of ammonium nitrate dissolved in 15-50% and preferably 20-50% by weight of said amino compounds, based on the weight of the mixture, and then at the site of use add to said solution additional ammonium nitrate to give a satisfactory slurry of ammonium nitrate-amino compound composition consisting essentially of ammonium nitrate and 2-14% by weight, and preferably 6-8%, of said amino compound, based on the weight of the mixture.

My new compositions suitable either for use as explosives or in the preparation of explosives consist essentially of a mixture of ammonium nitrate and the required amount of an amino compound represented by the structural formula HILT g.

Where R is selected from the group consisting of lower alkyl, lower hydroxyalkyl, and -C H NH and R is selected from the group consisting of hydrogen, lower alkyl and C H NH Examples of such amino compounds include primary and secondary amines, including diand tri-primary amines, and amino alcohols containing 14 carbon atoms. Compounds of this type include monoand di-methyl-, ethyl-, propyl-, isopropyl-, nbutyl-, secondary butyl-, and isobutyl-amines, ethylene diamine, diethylene triamine, monoethanolamine, monopropanolamine, butanolamine, 2-amino-l-butanol, etc. Solutions of ammonium nitrate in these amino compounds are preferably first prepared by thoroughly mixing the ammonium nitrate with the required amount of amino compound, 20-50% by weight of amino compound, based on the weight of the mixture, ordinarily being required. I can then continue the addition of ammonium nitrate to give an explosive composition in the form of a slurry or wet solid containing amino compound in the range of 2-14% by weight of amino compound, and preferably tions.

- hole.

6-8%, based on the weight of the mixture. I prefer, however, to transport the ammonium nitrate-amino compound composition of reduced sensitivity in solution form to the site of use before adding the additional ammonium nitrate.

The ammonium nitrate utilized in my invention for explosives is preferably essentially anhydrous pure ammonium nitrate or fertilizer grade ammonium nitrate, either uncoated or coated with various coating agents, such as resin, diatomaceous earth, etc. Pure anhydrous 'ammonium' nitrate is preferred. The amino compound such as, for example, the monomethylamine or dimethylamine, used in my invention is also preferably anhydrous.

When the ammonium nitrate and sufficient quantity of r the amino compound are brought into contact a solution mately 1.5. This increase in bulk density materially increases the etfective explosiveness of the charge. In mining operations, in particular, the requirement for smaller or fewer bore holes for a given charge materially reduces drilling costs. 7

My new compositions containing ammonium nitrate as the essential explosive ingredient are not subiected to the hazards in production and handling present in the use of previously known explosives containing ammonium nitrate by reason of the fact that they can be easily and simply prepared at the site at which they are to be used. In many instances, the explosives can be prepared directly in the bore hole by simply placing the ammonium nitrate charge in the bore hole and by passing a suitable amount of the said amino compound in gaseous or liquid form through the ammonium nitrate therein. Alternately, ammonium nitrate can be placed in the bore hole and an amount of a solution of ammonium. nitrate in said amino compound sufficient to give a final ammonium nitrate-amino compound composition of the desired composition and degree of sensitivity added there- 4. paring large amounts of a sensitive explosive at any one place, and thereby materially reduces the hazard to life and health of the personnel working in the area.

While my new explosive compositions consist essentially of ammonium nitrate and said amino compounds, they may also include varying amounts of different additives of the character customarily used in explosive compositions; such as compositions which increase or reduce the desired explosiveproperties of the mixture, or which sensitize or desensitize them. Other additives include compounds which add oxidizing or reducing potentials to the explosive compositions, or which catalyze the burning rate thereof, or which reduce the freezing points of the compositions when transported in solution form. Fuels which I have found to be useful in my explosives include ammonia; metals, aluminum or mag nesium; petroleum fractions, wood flour; carbon black; alcohols, such as methanol or ethanol; etc.

The sensitivity and general utility of my new ammonium nitrate-amino compound compositions as explosives will vary slightly with the particularamino compound employed as well as the amount thereof. The eifectiveness of an explosive mixture containing 7.95% by weight of monomethylamine as compared to a number of commercial explosives, using nitroglycerine as a standard, is

, shown in the following table.

My new explosive compositions can also be prepared in the bore hole by dissolving the said amino compound in a liquid in which it is soluble, such as ethanol when monomethylamine is used as'the amino compound, and

pouring the resulting amine solution over the ammonium nitrate charge previously placed in the bore hole. charge can, of course, include carbon black, ground coal, morpholine, lower alkyl alcohols, dimethylformamide, dimethyl sulfafide, aluminum, sulfur, ferrosilicon, parafiin wax,-resin, or other ingredients ordinarily incorporated into ammonium nitrate explosive composi- The ammonium nitrate-amino compound compositions of my invention require primer charges to initiate and propagate detonation waves through the charge. If

the bore hole in which the explosive is to be detonated is wet, horizontal, or slanting, the ammonium nitrate can he placed in a container such as a polyethylene bag or metal cartridge and the amino compound or ammonium nitrate-amino compound solution introduced into the container or cartridge just prior to its insertion in the bore In this manner, the hazards of mixing and trans-. porting the finished explosive compositions are avoided. It should be noted that the incorporation of the amino compound into the ammonium nitrate mixture, or the incorporation of an amount thereof to give compositions .containing the amino compound inamounts ranging from- 2-14% 'at the site of usage reduces the necessity of pre- 1 50% nitroglycerine gelatin dynamite containing ammonium nitrate An explosive containing approximately 92% ammonium nitrate and 8% carbon black.

of my invention can be prepared at the site of usage The. V

as required and in amounts needed and do not require the shipping, storage and handling precautions required for previous types of explosives. 1

While the explosive compositions of my invention containing as little as 2% of said amino compounds are sensitized to some extent, about 5-10% of amino compound such as monomethylamine is required to produce maximum sensitivity. While my ammonium nitrate-amino compound compositions are not cap sensitive, they have high sensitivity for a mixture of such high density; Le, a 92.1% by weight ammonium nitrate-7.9% monomethylamine mixture was found to require only a 70 g. pressed tetryl booster to completely detonate a column of explosive having a length of 28 inches and a diameter of 7 inches. The liquid compositions of my invention containing from about 15-50% amino compound have the same order of sensitivity as pure ammonium nitrate at sea level pressure.

The following table shows the use of a representative group of additives in my ammonium-nitrate explosives prepared with monomethylamine, using different ratios ammo ium n ra eand mono e hy newh h I have found to give effective explosives.

TABLE II Ammo- Mononlum Fuel Percent methyl- Nitrate,

amine Percent Coal Dust 3 Wheat Flour 2 91 Wood (Powdered).... 2 90 Garbo Blac 3 90 Ammonia 2 92 2 98 6 94 26 75 The following table sets out some of the physical properties of ammonium nitrate-monomethylamine explosive compositions. 7

TABLE III Physical properties of ammonium nitrate-monoand di-methylamine solutions Percent Wt. Monomethylamine 18.1 27.1

abs. 763 691 447 333 79 1. 8 Ignition temperature 400450 C 400-450" 0 Percent Wt. Dimethylamiue 24. 97 Vapor Pressure:

Freezing p0 Percent W Density:

A practical method of producing a satisfactory explosive composition from ammonium nitrate and dimethylamine is carried out as follows: A tin can 7 /2 inches ID. by 24 inches long is filled with dry granular high density ammonium nitrate and then a solution of ammonium nitrate in dimethylamine (75% by weight ammonium nitrate-25% by weight dimethylamine) is added so as to fill all of the voids, using a ratio of 0.4 pound of solution to 1.0 pound of granular ammonium nitrate. The resulting composition consists approximate ly 92% ammonium nitrate and 7% dimethylamine.

The use of my new ammonium nitrate-amino compound explosive compositions is illustrated by the following examples.

EXAMPLE I Four deep bore holes were drilled in a row into a strata of hard rock overburden containing seams of taconite found to be particularly difficult to drill and blast 35 feet deep. These holes were charged with 40 pound cans of explosives. Each can, 7% inches diameter by 16 inches long, was charged with a composition consisting of ammonium nitrate and dimethylamine in the ratio of one pound of ammonium nitrate to 0.39 pound of a composition consisting of 75.87% amomnium nitrate and 24.13% by weight of dimethylamine. Ten of these cans were placed in each of two of the bore holes and nine cans were placed in each of the other two bore holes. A 6 /2 inch diameter Nitramite primer (Du Pont, weight 9 pounds) was placed in the middle of the charges (above the fifth can) and a second Nitramite primer was placed under the top can. A single line of Primacord was run to the two primers. All of the holes contained con- EXAMPLE II Liquid monomethylamine was added to ammonium nitrate in comminuted form in an amount sufficient to give a solution of the ammonium nitrate in the monomethylamine. The resulting composition contained 79.56% ammonium nitrate and 20.44% monomethylamine. Commercial coated ammonium nitrate was then mixed with this solution in the ratio of 0.614 pound of solution to 1 pound of ammonium nitrate. A quart size tin can was filled with this slurry which consisted of 90.36% by weight of ammonium nitrate, 7.78% by weight of monomethylamine and 1.85% by weight inert (coating agent). The filled can then was buried in soil so that the top of the can was level with the surface of the ground. Two 37 gram blocks of Pentolite booster explosive were taped to the top of the can. Two No. 8 electric dynamite caps were pressed into holes in the Pentolite blocks. The caps were then detonated, initiating detonation of the Pentolite and the latter in turn initiating the ammonium nitrate-monomethylamine compositions. A crater which was about 72 inches in diameter and 20 inches deep was formed. A comparison test in which the same type Pentolite booster was taped to a quart can filled with water produced only a slight depression in the soil about 16 inches in diameter by 7 inches deep.

This application is a continuation-in-part of my US. patent application Serial No. 681,437, filed September 3, 1957, and US. Serial No. 735,987, filed May 19, 1958.

Now having described by invention, what I claim is:

1. Ammonium nitrate compositions suitable for use in the explosive art consisting essentially of mixtures of ammonium nitrate with 250% by weight, based on the weight of the mixture, of an amine having the structural formula Hit k! where R is selected from the group consisting of lower alkyl, lower hydroxyalkyl and -C H NH and R is selected from the group consisting of hydrogen, lower and C H NH 2. Ammonium nitrate compositions suitable for use as explosives consisting essentially of mixtures of ammonium nitrate with 2-14% by weight, based on the weight of the mixture, of an amine having the structural formula 1 t where R is selected from the group consisting of lower alkyl, lower hydroxyalkyl and --C H NH and R is selected from the group consisting of hydrogen, lower 'alkyl: and C H NH ,7 r v 4. Ammonium nitrate compositions suitable for use as. explosives consisting essentially of mixtures of ammonium nitrate and 214% by weight, based on the :weight of the mixture, of monomethylamine. V

5. Ammonium nitrate compositions suitable for use as explosives consisting essentially of mixtures of ammonium nitrate and 214% by weight, based on the weight of the mixture, of dimethylamine.

"in producing explosives consisting essentially of mixtures of ammonium nitrate with 20-60% of dimethylam'ine, based on the weight of the mixture.

No referenees cited UNITED STATES PATENT OFFICE QEHFNATE QECTIQN Patent No, 2376 137 Marsh 21 Leonard A, Stengel It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5 TABLE II under the heading "f-innrnonxium Nitrate Peroenid and opposite Coal Dust for "0" read 90 Signed and sealed this 5th day of September 1961a (SEAL) Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. LADD Commissioner of Patents USCOMM-DC UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.0 2,976 137 March 21 1961 I Leonard A Stengel It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5 TABLE 11,, under the heading "Ammonium Nitrate Percent and opposite Coal Dust for "0" read 90 a Signed and sealed this 5th day of September 1961,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC

Claims

1. AMMONIUM NITRATE COMPOSITIONS SUITABLE FOR USE IN THE EXPLOSIVE ART CONSISTING ESSENTIALLY OF MIXTURES OF AMMONIUM NITRATE WITH 2-50% BY WEIGHT, BASED ON THE WEIGHT OF THE MIXTURE, OF AN AMINE HAVING THE STRUCTURAL FORMULA