US3676235A

US3676235A - Explosive composition containing ammonium nitrate and an organic sensitizer dissolved in dimethylformamide

Info

Publication number: US3676235A
Application number: US770093A
Authority: US
Inventors: Edwin H Nuscher; Jack D Slater
Original assignee: Kaiser Aluminum and Chemical Corp
Current assignee: S & P INVESTMENTS CORP A CORP OF
Priority date: 1968-10-23
Filing date: 1968-10-23
Publication date: 1972-07-11
Anticipated expiration: 1989-07-11

Abstract

AMMONIUM NITRATE EXPLOSIVES ARE CONVENIENTLY PREPARED BY DISSOLVING A SENSITIZING COMPOUND SUCH AS TNT IN DIMETHYL FORMAMIDE AND THEN MIXING IT AT AMBIENT TEMPERATURES WITH AMMONIUM NITRATE AND ADDITIONAL FUEL COMPONENTS. THE RESULTANT MIXTURE IS UNIFORM IN PERFORMACE OVER EXTENDED PERIODS OF TIME.

Description

EXPLOSIVE COMPOSITION CONTAINING AMMO- NIUM NITRATE AND AN ORGANIC SENSITIZER DISSOLVED IN DIMETHYLFORMAMIDE Edwin H. Nuscher and Jack D. Slater, Savannah, Ga.,

assignors to Kaiser Aluminum & Chemical Corporation, Oakland, Calif. No Drawing. Filed Oct. 23, I968, Ser. No. 770,093

Int. Cl. C06b 9/00 US. Cl. 149-39 8 Claims ABSTRACT OF THE DISCLOSURE Ammonium nitrate explosives are conveniently prepared by dissolving a sensitizing compound such as TNT in dimethyl formamide and then mixing it at ambient temperatures with ammonium nitrate and additional fuel components. The resultant mixture is uniform in per formance over extended periods of time.

BACKGROUND Ammonium nitrate is a commercially desirable explosive material since it can be obtained relatively cheaply. However, to be effective, the commercial crystalline or granular ammonium nitrate must be admixed with an oxidizable fuel material. Many organic and inorganic items have been used as fuels. Typical organic materials are carbon black, polysaccharides, fuel oil, tall oil, resins, and urea. Inorganic materials have been powdered, flaked and granular aluminum, iron, magnesium, and sulfur. Mixtures of these are frequently employed, e.g. fuel oil and aluminum.

Ammonium nitrate and oxidizable fuel mixtures are capable of exerting powerful explosive forces. However, ammonium nitrate-fuel mixtures may be diflicult to detonate without special boosters. For some time now organic compounds such as mononitrotoluene, dinitrotoluene, trinitrotoluene, nitrobenzene, nitroglycerine, urea, rosin, or mixtures of these materials have been added as sensitizers or boosters.

Explosive compositions of ammonium nitrate, fuels, and sensitizers, have found many important civil and military applications. The production of ammonium nitrate based explosives has been commercially practical because of the relatively loW cost of ammonium nitrate as well as the efforts made by manufacturers to hold the use of high cost sensitizers at a minimum and to keep production techniques simple and safe.

In the preparation of ammonium nitrate based explosives sensitized with organic compounds, an objective of the explosive art has been to secure the most practical possible intimate and uniform blend. One procedure has been to grind ammonium nitrate and a sensitizer together in mills. Such a procedure occasionally results in a lack of uniformity in both composition and properties. An other procedure has been to heat a sensitizer to its melting temperatures and then mix it into ammonium nitrate, which may also be heated. These procedures, which requires heating or grinding of the sensitizer, presents an undesirable hazard.

DISCLOSURE It is an important object of this invention to provide a sensitized ammonium nitrate composition by simply mixing a sensitizer and ammonium nitrate at ambient 3,675,235 Patented July Ill, 1972 temperatures, that is temperatures between about 50 F. and about 100 F., without heating or grinding of the composition.

Another important object of this invention is to provide an ammonium nitrate explosive, containing a sensitizer, which is uniform in performance over extended periods of handling, moving, or storage.

Another object of this invention is to provide an explosive mixture which is relatively inexpensive because ammonium nitrate is utilized as the principal explosive material.

A further object of this invention is to provide an explosive mixture based on ammonium nitrate and containing an additional, useful, economical and compatible fuel, in which the sensitizer is an organic compound or mixture of organic compounds.

We have found that most organic compounds which are suitable for service as sensitizing materials have excellent solubility in dimethylformamide (DMF). As examples, over ambient temperatures, a solution of 55-60% dinitrotoluene (DNT), a solution of 5055% trinitrotoluene (TNT), and a solution of 5055% rosin can be prepared in DMF. At these temperatures, DMF is a liquid (melting point 61 C. and boiling point 152 C.) with a vapor pressure of 3.7 mm. at 25 C. and with a reported toxicity less than or no greater than the sensitizing nitro compounds that might be used. DMF is also an excellent fuel in itself for the preparation of an ammonium nitrate explosive composition.

We have found that the objects of this invention may be accomplished by admixing suitable proportions of ammonium nitrate with a sensitizer which has been dissolved in DMF. An additional fuel component such as fuel oil, aluminum, etc., may also be incorporated. The sensitizer may be any of the organic compounds previously recited, although a nitrotoluene or rosin is preferred. A particularly useful organic material is a solution of rosin in DMF because rosin may be used as both the sensitizer and additional fuel component. Preferred compositions will contain from about to about ammonium nitrate, about 2% to about 10% DMF, about 1% to about 6% sensitizer, and about 3% to about 10% additional fuel. The selected materials are mixed in any convenient mixing means at ambient temperature. By virtue of the nature of the ingredients, the final compositions will be substantially anhydrous, i.e. less than 0.50% water, and preferably less than 0.20%. Also, the solution of sensitizer in DMF is adsorbed into the porous ammonium nitrate. As a result, the uniform compositions of the invention are free-flowing, dry mixtures and they remain so over extended periods of time.

A family of explosive mixture having a wide range of explosive properties can be prepared in accordance with this invention. For example, the finer the particle size of ammonium nitrate and/or aluminum, the greater the sensitivity of the mixture. Particularly desirable explosive properties have been obtained with mixture in which at least 50% of the ammonium nitrate was 20 mesh. Also, sodium nitrate may be substituted for up to 25% of the ammonium nitrate, thus increasing the density of the overall mixture. In this way it is possible to formulate a mixture with a density greater than 1, which is important if the mixture is to be detonated under water.

Mixtures prepared according to this invention were tested by detonation with a #6 blasting cap to determine sensitivity. The power developed was estimated by using the small lead black compression test (Physical Testing of Explosives U.S. Department of Commerce,

ceeding examples. They are summarized in the following table.

Percent Mix TNT DNT Inches, compres- DMF NHgNO; Fine Al Coarse A1 sion 30 Mesh Control #1 #1 Control #2 lemon *Power mix #1 and #4 are commercial ground, physical mixture containing NH4N03, TN T,'-DN '1 oil, NaNOa and aluminum powder.

Bureau of Mines, Bulletin 346, 1931). The compression of a 1 /2" x 3" lead block by a 140 gram test charge was compared with that made by a 140 gram charge of flaked or granular TNT.

Examples of compositions made in accordance with this invention are described below for purpose of illustration.

EXAMPLE 1 EXAMPLE 2 2.87 parts of gum rosin were dissolved in 2.78 parts of DMF at room temperature. This solution was intimately mixed into 89.20 parts of NH NO which had been ground fine enough so that no discrete prills remained. 5.15 parts '30 mesh aluminum was evenly mixed into the mixture.

This material was tfired in a 1 /2" diameter container on the test lead block and gave a compression of inch. It 'was sensitive to a #6 blasting cap.

EXAMPLE 3 4.57 parts of TNT were dissolved in 5.89 parts of DMF at room temperature. This solution was intimately mixed into 86.27 parts of NH NO which had been ground fine enough so that no discrete prills remained. 3.26 parts 30 mesh aluminum was distributed evenly through the mixture.

The composition was fired in a 1 /2" diameter container on the test lead block and gave a compression of inch. It was sensitive to a #6 blasting cap.

EXAMPLE 4 Additional materials, sensitive to a #6 blasting cap, were prepared according to the procedure of the pre- What is claimed is:

1. A substantially anhydrous, uniform explosive composition comprising ammonium nitrate and a sensitizing amount of an organic sensitizer dissolved in dimethylformamide said organic sensitizer being a member selected from the group consisting of a nitrotoluene, nitrobenzene, nitroglycerine, urea, rosin or mixtures thereof.

2. A composition of claim 1 wherein the sensitizer is a nitrotoluene.

3. A composition of claim 1 in which the sensitizer is a solution of about 5% to about 50% rosin in dimethylformamide.

4. A composition of claim 1 to which an additional fuel component has been added.

5. A composition of claim 4 in which the additional fuel component is aluminum.

6. A composition of claim 5 wherein the sensitizer is a nitrotoluene.

7. A method for making a uniform explosive composition which comprises mixing at ambient temperatures ammonium nitrate in a solution of an organic sensitizer for said dimethylformamide and ammonium nitrate until a uniform mixture is obtained, said organic sensitizer being a member selected from the group consisting of a nitrotoluene, nitrobenzene, nitroglycerine, urea, rosin or mixtures thereof.

8. The process of claim 7 wherein an additional fuel component is uniformly incorporated into the mixture.

References Cited UNITED STATES PATENTS 3,190,777 6/1965 Breza et a1. 14957 3,282,752 11/1966 Clay ct a1 149-44- 3,307,986 3/1967 Grant 14944 3,379,587 4/1968 Cook 149-44 3,390,029 6/1968 Preckel 14944 3,406,051 10/ 1968 Fearnow 14957 3,406,051 10/1968 Fearnow 149105 5 CARL D. QUARFORTH, Primary Examiner S. J. LECHERT, JR., Assistant Examiner U.S. Cl. X.R.