US2220891A

US2220891A - Ammonium nitrate explosive composition

Info

Publication number: US2220891A
Application number: US289187A
Authority: US
Inventors: Cook Melvin Alonzo; Davis Clyde Oliver; Lawson Walter Eastby
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1939-08-09
Filing date: 1939-08-09
Publication date: 1940-11-12
Anticipated expiration: 1957-11-12

Description

Patented Nov. 12, 1940- UNITED "STATE s "PATEN OFFICE AMMONIUM NITRATE EXPLOSIVE COMPOSITION .-:-No Drawing. Application August 9, 1939,

. Serial No. 289,187

' screa s. {01.52 -14) "This invention relates to new vand improvd ammonium nitrate explosive compositions, and

more particularly 'tos'uch ones as can be packed to high densities and which possess superior sensitiveness properties'atsuch high densities.

It is well known that ammonium nitrate constitutes an efiective blastingagent when blended Chemistry.

with combustible materials in amounts sumcient to give oxygen-balanced compositions and with a 1o. satisfactory 'Jsensitizing -agent. While nitrogl'ycerin has been the most co'mmonly-used sensitizenyery. eflicient blasting explosives are in regular production comprising ammoniumnitrate blended with solid, non-explosive sensitizing in- 20 necessary in order that the product shall maingredients capable ofv utilizing the excess oxygen of the ammonium nitrate for their own complete tain itsfexplosive properties unimpaired during storage. The aflinity of ammonium nitrate for water makes this particularly important, since.

. 35 as the invention is described more'at length here-' inafter. The foregoing objects are accomplished, and the disadvantages of the prior art overcome, by the formulation of explosive compositions con- 40 taining ammonium nitrate as the predominant ingredient, a sensitizer for the ammonium nitrate, an inorganic nitrate, and combined ammonia. By combined ammonia we mean combined molecular ammonia.

5- We find it desirable to employ in the compositions of our invention an inorganic nitrate which is capable of reactingwith gaseous ammonia, for example to form anietal ammine, an ammoniate, or other ammonia addition compound. In 50 other words, this essential inorganic nitrateis one other than the nitrates of the alkali metals, since the latter failed to form said addition compounds with ammonia. By the term ammine we are not referring to the organic amines, but to so the well recognized inorganic-compounds eon- I taining combined molecular ammonia, frequently referred to as the ammoniates, or as the metal ammines, or synonymously as an inorganic compound containing ammonia of crystallization. Discussion of compounds of this type, for exam- 7 pie, is found in Friend's Textbook of Inorganic Volume 10 of the same is devoted entirely to the metal ammines. The compounds are. also referred to in the book by Franklin, Nitrogen System of Compounds, page 38. The 10 letter term has been employed by Edward, C. Franklinon page 38 of his book entitled The Nitrogen System of Compounds.

Ammonium nitrate should be present as the preponderant ingredient, that is in an amount 5 "greater than 50%. Preferably, however, our compositions will contain more than 75% ammonium nitrate. Various sensitizers for the ammonium nitrate may be used which are capable of oxidation by, and of utilizing at least a portion of, the excess oxygen of the ammonium nitrate. The nitroaromatic hydrocarbons and compounds comreaction product of the inorganic metal nitrate and ammonia should be present in an amount between 0.1 and 10.0%.

Various methods are available for preparing the explosive compositions according to our invention, especially those described in our copending applicati0h,-Serial No. 289,188, dated Aug. 9, 1939. According to our preferred method,

calcium cyanamide is heated to a temperature around 80' C. with a blend of ammonium nitrate and dinitrotoluene, whereby gaseous ammonia is given off as a reaction product and calcium 'nitrate is formed. The ammonia reacts with the calcium nitrate, presumably to form a calcium nitrate ammine. Both the initial product,c'al'- .cium cyanamide and calcium nitrate, are fusion point depressants for the ammoniumnltrate. The organic sensitizer should be one having a melting point such that the material is atleast partly iused at the temperature of mixing of the explosion; hence it should desirably have a fusion point below 100 C.

We find the advantages of the presence of the 5 reaction product of ammonia with calcium ni- Certain ammonium nitrate explosives are now in use which contain only non-explosive sensitizers. These are relatively insensitive explosives. Some are so much so that they are incapable of detonation by a commercial blasting cap, though they can be readily detonated and caused to 'propagate with undiminished high velocity, when initiated by a suitable booster charge of trinitrotoluene or other high explosive. With such explosives, densities greater than 1.15 are frequently impractical, since there is too great a chance of failure to detonate. Utilizing the compositions of the present invention, however, densities mudh higher than; 1.15 are utili'zable. Preferably the explosive will be enclosed in a completely water-tight and air-tight container such as a metal can. Under such conditions the composition is protected completely against moisture.

As examples of explosive compositions according to our invention, the following will serve:

Example I An explosive composition was prepared, which comprised 84% ammonium nitrate, 12% dinitrotoluene, and 4% calcium nitrate. The maximum density at which propagation of the explosive could be continuously effected was found to be 1.25. The velocity of detonation at this density was determined to be 1750 meters per second. This example contained no free ammonia for combination with the calcium nitrate, and the relative insensitiveness and low velocity are apparent.

Example II The explosive composition of this example com- 50 prised 83% ammonium nitrate, 12% dinitrotoluene, and 5% of a compound of calcium nitrate and ammonia, which may be designated 55 The increased sensitiveness, due to the presence of the reaction product of ammonia and the calcium nitrate, can be seen from the maximum propagating density of over 1.35, in comparison with 1.25 for the composition of Example I.

60 Moreover the velocity of this composition at a density of 1.30 was 3830 meters per second.

Example III Ezample IV The composition comprised 81.5% ammonium nitrate, 12.0% dinitrotoluene, and 6.5% of the reaction product of strontium nitrate with ammonia. The improvement eflected by the pres- 5 ence of this reaction product is shown by the fact that the composition of this example has a maximum propagating density of 1.27 against 1.21 for a similar composition containing only strontium nitrate. Likewise improved velocity 10 was shown, 3325 meters per second at a density of 1.25 against 1900 meters at 1.20.

Example V A composition was prepared comprising ap- 15 proximately 81.5% ammonium nitrate, 12.0% dinitrotoluene, and 6.5% of a reaction product of hydrated cupric nitrate and ammonia. The eX- plosive at a density of 1.30, in metal containers of 2" diameter, gave consistently high velocity 20 detonations, when properly primed. The efiicacy of the ammonia addition product was shown from the fact that a similar composition containing cupric nitrate, not ammoniated, failed to detonate at a density of 1.20. 25

Various inorganic nitrates and other salts are available which are effective in increasing the sensitiveness of the high ammonium nitrate compositions of our invention. Such salts 'include calcium nitrate, barium nitrate, strontium nitrate, zinc nitrate, lead nitrate, cobalt nitrate, copper nitrate, cobalt perchlorate, and the like. While we have excluded the nitrates of the alkali metals from our invention with respect to compounds with ammonia, it should be understood that sodium nitrate or other alkali nitrate may be present in the role of oxidizing agent or other capacity. Likewise many other ingredients may be included.

It has been stated previously that we may ap- 40 ply our invention efiectively in the case of capinsensitive explosives which are capable of detonation by a booster charge, whereby these blasting agents are made more certainly detonable- It may likewise be utilized to sensitize capinsensitive compositions and make them sensitive to commercial blasting caps. Furthermore, it is applicable in the case of certain explosives of high ammonium nitrate content which thereby become practical for use in smaller diameters than would otherwise be possible.

We have described our invention at length in the foregoing, but it will be understood that many variations may be introduced without departure from the scope of the invention. We wish to be limiteed, therefore, only by the following patent claims:

We claim:

1. An ammonium nitrate explosive composition having a density greater than 1.15, said composition comprising more than 50% ammonium nitrate, a sensitizer therefor, an inorganic nitrate other than those of the alkali metals, and molecular ammonia combined therewith.

2. An ammonium nitrate'explosive composition having a density greater than 1.15, said composition comprising more than 50% ammonium nitrate, an organic sensitizer for the ammonium nitrate, and the reaction product of ammonia with an inorganic metal nitrate other than those of the alkali metals.

3. An ammonium nitrate explosive composition having a density greater than 1.15, said composition comprising more than 50% ammonium. nitrate, an organic sensitizer therefor, and

an ammine of an inorganic nitrate other than be detonated by means of a suitable booster those of the alkali metals.

4. An ammonium nitrate explosive character- 'ized by high density, said composition comprising more than 50% ammonium nitrate, an organic sensitizer for said ammonium nitrate, and the reaction product of ammonia with calcium nitrate.

5. An ammonium nitrate explosive composition having a density greater than 1.15, said composition comprisingemore than "75% ammonium nitrate, between 0.5 and 20.0% of an organic sensitizer therefor, and between 0.1 and 10.0%

of the reaction product of ammonia with a metal nitrate other than those of the alkali metals.

6. An ammonium nitrate explosive composition characterized by high density and of a degree of sensitiveness such that it is incapable of detonation. by a commercial blasting cap but can charge, said composition comprising more than 75% ammonium nitrate, between 0.5 and 20.0% of an aromatic nitrocompound, and between and 10.0% of the reaction product of ammonia with calcium nitrate. v

'7. The explosive composition of claim 6, in which the aromatic nitrocompound is dinitrotoluene.

8. An ammonium nitrate explosive comprising more than 50% ammonium nitrate and an inorganic nitrate other than those of the alkali metals containing ammonia of crystallization combined with said nitrate, said compound being intimately dispersed within the body of the ammonium nitrate as a sensitizer for the latter.

MELVIN ALONZO COOK. CLYDE OLIVER DAVIS. WALTER EASTBY LAWSON.