US2033198A - Explosive - Google Patents

Description

Patented Mar. 19,1936

UNITED STATES PATIENT OFFICE ExrLosrvn No Drawing. Application May 29, 1934,

- Serial 1:10. 728,065

"is Claims. (01. 102-6) This invention relates .to explosive compositions modified from the standard types of nitro-.

glycerin explosives and more particularly to such explosives that have a relatively low degree of sensitiveness.

Most of the commercial dynamites in general use at the present time contain nitroglycerin as the principal explosive ingredient. In some of these explosives, the nitroglycerin content has been replaced in part by ammonium nitrate. This exchangegives an economic advantage without sacrificing explosive strength, since the amy monium nitrate is sensitized by the amount of nitroglycerin present, and therefore develops satisfactory strength.

In another type of explosives in common use, the gelatin dynamites. the nitroglycerin has been gelatinized by the solution in it of a small amount of nitrocotton. In this way a plastic explosive is obtained which has many advantages over the ungelatinized explosive, particularly with respect to increased density and improved 'water resistance. In these gelatin dynamites, as in the nongelatinous, exploflves, a portion of the nitrogylcerin may be replaced by ammonium nitrate, if

25 desired, in which case ammonia gelatins are obtained.

The explosives described in the foregoing, as containing nitroglycerin as the explosive ingredient and no ammonium nitrate, are commonly termed straight dynamites. Similarlythose explosives, in which a portion 01' the nitroglycerin has been replaced by ammonium nitrate, are

, termed ammonia dynamites. The gelatin dynamites are classified in the same way as straight 35 gelatins and ammonia gelatins.

All theforegoing'types of dynamites are in general use in large quantities, and their properties are well understood and standardized. Such explosives have proved very satisfactory in practical use, and are commonly brought to explosion by means of the usual blasting caps, that is by No. 6 or No. 8 caps. These two grades of standard caps-are defined in Bulletin 59 of the United 45 States Bureau of Mines which specifies that No. 6 1 and No. 8 caps shall contain the equivalents of oneand two grams of mercury fulminate or fulminate composition respectively. As a matter of fact, if the standard explosives in common use are not'sensitive to the ordinary blasting caps, and capable of being consistently detonated thereby, they are considered altogether unsatisfactory for use in blasting operations, since mis fires and. failures bring increased hazards in removing the unexploded charge.

An object of our invention is to provide explosives so modified from the standard types of nitroglycerin explosives "that they have a greatly reduced degree of sensitiveness. A further object 60 is to provide explosives which are incapable of detonation by ordinary means, but may be detonated by an adequate booster, thereby providing greatly increased safety in themanufacture and use of blasting explosives. A still further object of our invention is to bring about the above decreased sensitiveness by a replacement of a portion of the nitroglycerin in the explosive by less sensitive and less expensive ingredients. Further is capable of detonation bymeans of a proper amount of a high explosive booster charge. We have found that this degree of insensitiveness can be obtained without detracting from the practical value of such explosives provided the detonation of the explosive is brought about by means of an adequate booster charge of other high explosives. In other words, we have found that nitroglycerin explosives, desensitized, as above described, will detonate and propagate with full efliciency provided the detonation is initiated with an adequate booster.

The fact that such an explosive can not be detonated by means of commercial blasting caps would ordinarily be considered a disadvantage. It is apparent upon further consideration, however, that the less sensitive an explosive can be, and yet be satisfactory for use, the greater are the resulting advantages, particularly with respect to safetyin handling. Many additional advantages in favor of low sensitiveness will be readily apparent to those: skilled in the art of explosives and their manufacture.

In producing compositions according to our invention, we may start with explosives similar to the usual commercial dynamites. If a straight dynamite is chosen and a suflicient. amount of anaromatic nitrocompound, for'example mononitrotoluene, is introduced into the composition,

' while at the same time a portion of the nitroglycerin content is replaced, an explosive is obtained which is sufiiciently insensitive that, while it will not detonate by a, force equivalent to that of a No. 8, cap, it can be made to do so by means of an adequate booster. Since the straight dynamites are initially very sensitive, a relatively inhave found that the desensitizing effects of such compounds are in inverseratio to their nitrogen sensitive nitrocompound must be used, since we contents. If desired, other agents having a greater desensitizing power may -be included with the nitrocompound, for example, a parafiin hydrocarbon such as petroleum jelly. Under these conditions the choice of the nitrocompound is not so limited with respect to the nitrogen content.

In a similar manner, the usual ammonia dynamite formulas can be brought to a low degree of sensitiveness by the replacement of a portion of the nitroglycerin by the proper amount of a nitrocompound of the aromatic series. Since the ammonia dynamites are in general less sensitive than the straight dynamites, a lesser amount of nitrocompound is sufficient to desensitize the compositions to the point where the explosive requires a booster charge for itsdetonation. While we have indicated above the addition of mononitrotoluene, in the case of straight dynamites, the more highly nitrated derivatives may be used as well, for example, dinitrotoluene and trinitrotoluene. Commercial trinitrotoluene, however, has in general very little desensitizing effect, because of its more highly nitrated condition, and for' this reason would be satisfactory only in explosives with relatively low initial sensitiveness, or in combination with other compounds of lower degree of sensitiveness, or having a tendency to liquefy the trinitrotoluene.

The sensitiveness of both straight and ammonia gelatins may be likewise reduced by a replacement of a substantial portion of their nitroglycerin content by a nitrocompound of the aromatic series, and-we find the application of our invention particularly advantageous in the case of the ammonia gelatins.

As represenative examples of explosive compositions that may be used as the starting point in the preparation of explosives according to our invention, the following are given as illustrative:

If it is desired, for example, to produce a modified 40.0% ammonia dynamite by the replacement of a portion of the nitroglycerin by a suitable nitrocompound, it will be found that the amount of replacement necessary to 'yield an. explosive insensitiveto commercial blasting caps will depend on the nitrocompound used, and particularly on its sensitiveness. With trinitrotoluene, for example, practically a 90% replacement is necessary to give the desired results. With dinitrotoluene on the other hand, a replacement of approximately 75% will give the same result. With mononitrotoluene and nitro-benzene, the replacements necessary will be approximately 50.0% and 55% respectively.

When explosives, on the other hand, are produced on a modified formula for 40% ammonia gelatin, by replacement of a portion of thenitroglycerin by a nitrocompound, it is found that, when trinitrotoluene is used, even 100% replacement of the nitroglycerin does not desensitize the explosive to the point where a. booster charge is required. Furthermore, the limited solubility of trinitrotoluene in nitroglycerin renders it not well Solid nitrocompounds of the aromatic In the case of dinitrotoluene, approximately a 55% replacement gives the sensitiveness desired, while with mononitrotoluene and nitrobenzene, a replacement of an amount of nitroglycerin slightly less than of that present is sufilcient to give the desired result.

While various compositions of explosives are satisfactory according to our invention, the following may be given as further illustrating specific embodiments thereof:

Modified 40% ammonia dynamite Modified 40% ammonia gelatin Percent Nitroglycerin ll. Mpnonitrotoluen Nitrobenzene Nitrocotton Ammonium nitrate Sodium nitrate...

The so-called straight dynamites and gelatins may be altered to reduce their initial sensitiveness to the desired degree in a substantially similar manner.

The amount of nitrocompound that should be used to give the most advantageous results is dependent on several factors, for example the type of dynamite in which the replacement of the nitroglycerin is made, the density of the dynamite, and the desentizing power of the nitrocompound. In the examples given it will be understood that the density is that normal to the standard nitroglycerin explosives.

Many difierent nitrocompounds of the arcmatic series are available for use according to our invention, the choice of compound depending largely on the type of dynamite in which the nitrocompound is to be substituted and on the degree of sensitiveness of the original explosive.

As we have indicated in the foregoing, the desensitizing effect of the nitrocompound is in general inversely proportional to the number of nitrogroups present and to the nitrogen content. As examples of mono-nitrocompounds may be mentioned the mono-nitro derivatives of benzene, toluene, xylene, naphthalene, phenol, and the like. Similarly, the corresponding di-nitrocompounds maybe used with relatively less desensitizing efiect than in the case of the mononitrocompounds. Furthermore, certain of the corresponding trinitro derivatives may be employed, particularly those of toluene, xylene, and naphthalene. With such nitrated materials, however, the desensitizing efiect is slight and it may be desirable to employ simultaneously a which case there has doubtless been a slight decrease in the sensitiveness of the explosive.

. Such explosives, however, containing nitrocom- Heretofore, in the replacement of nitroglycerin by nitrocompounds, it has been immaterial whether such nitrocompounds were liquid or solid, since a relatively small amount was used, which was readily 'soluble in the nitroglycerin. According to our invention, however, in the replacement of nitroglycerin in the gelatin type of dynamite, it. is important that the kind and amount of nitrocompound be such that the combination of nitroglycerin and nitroconipound be substantially liquid at ordinary room temperatures, in order that satisfactory plasticity and gelatinization may result with the, nitrocotto'n. Whereasin explosive compositions according to the prior art, the nitrocompound has been emplpyed to depress the freezing point of the nitroglycerin, the replacement 'of nitroglycerin, according to our invention, is such that the nitroglycerin substantially depresses the freezing point of the nitrocompound.

Since it is important, in thecase of gelatinous explosives, that the combination of nitroglycerin and nitrocompound be substantially liquid at ordinary room temp ratures, the nitrocompound for use, or the mixtures of nitrocompounds, should be so chosen that a liquid combination results.

. For example, nitroglycerin and liquid mono-nitro- I compounds of the aromatic series are miscible in.-

all proportions and give liquid combinations. Likewise, nitroglycerin gives liquid compositions in practically all proportions with the so-called liquid 'dinitrotoluene, which is a product obtained 7 reason of the chlorate or perchlorate content,

in the refining of the 'mixed isomers of 'dinitrotoluene, which result from the direct nitration of toluene. If solid dinitrotoluen'e and trinitrotoluene are'employed with nitroglycerin, sumcient oi the mono-nitrocompound may be desirable to ensure a liquid product.

Whereas we have'described our invention as particularly applicable to compounds having in-' corporated. therein nitroaromatic compounds, other organic compounds which are substantially soluble in nitroglycerin may be similarly used, such as ketones, ethers, primary alcohols, polybydric alcohols, amino compounds, acetic esters, and the-like. These may be employed either alone or combined with the nitroaromatic compounds.

Some of the organic liquids suitable for our purpose find partioular value in facilitating the production of a nitroglycerin-nitroaromatic combination that will be liquid even at very low temperatures, such as prevail in winter through their mutual solvent action on both the nitroglycerin and nitroaromatic compounds,

, We are aware that nitrocompounds of the arc:

matic series have been used heretofore inexplosives containing substantial amounts of chlo rates and perchlorates, in the presence oi relatively small amounts of nitroglycerin. Such explosives are beyond the scope of our invention, however, since "they are relatively sensitive by and are readily detonated by the ordinary coinmercial blasting caps and are fired in this manner.

The explosive compositions in accordance with the present invention are not adapted for use in blasting operations except in columns or masses having a diameter equal to or greater than that of a two-inch circle, or a cross-sectional area of approximately three square inches, and employed in combination with a booster charge of high explosive, all as described in the co-pending application of Kirst, McCoy and Woodbury, Serial No. 599,592, filed March 17, 1932. We have found that such compositions are not sufiiciently sensitive when used in masses having dimensions less than those specified in the foregoing, to propa-' gate satisfactorily and with certainty.

The method of blastingto be used withthese explosives involves the useof main'charges of explosives having a degree of insensitiveness within definite limits. These limits statethat the explosive, when unconfined, shall be incapable of detonation by means of a commercial No. 8 blasting cap, but capable of detonation and propagation when primed with 1000 grams of trinitrotoluene or the equivalent thereof, as herematter described.

It has been found that explosives of the above sensitiveness can be made to detonate and propagate continuously with full efiiciency, when loaded into drill holes and primed with one or more booster charges of a more readily detonated explosive, for example one of the higher c0mmercial grades of nitroglycerine or nitrostarch dynamites. In order that the proger sensitiveness may be obtained, the explosiv must not betoo insensitive. In the case of the compositions cited heretofore, the replacement of the nitroglycerine by nitrocompounds of the aromatic series must not be carriedto a point where the compositions can not be detonatedby means of 1000 grams of trinitrotoluene.

The sensitiveness of the explosives according to our invention may be determined by the fol-' lowing-test, in which a single paper-wrappedv 4% x 8" cartridge of the explosive to be tested is placed vertically on a cylindrical lead test block, 2%" in diameter and 4 long, supported on a steel plate, and brought to detonation. The

.primer to be used has the same diameter as the explosive under. test, namely 4%", and consists of trinitrotoluene compressed to a density of 0.95.

The specific procedure consists in determining the minimum amount of said primer, enclosed in a paper wrapper, which will cause the insensitive explosive under test'to detonate and propagate consistently throughout the entire length of 8 inches and give a definite compression of the lead'test block. Thevcompression of the lead block will vary widely, and will depend both on the completeness of the propagation and on the velocity of detonation of the test explosive. Using the above procedure, it is necessary that theexplosive be brought to detonation and produce a definite compression by not more than 1000 grams of trinitrotoluen, in order that it may fall within the sensitiveness limits prescribed by our invention.

The same test procedure may be employed, when determining the ability to detonate by means of a No. 8 cap, with the exception that' the cap is inserted -'c lirectly in the explosive.

blast and where the number of men engaged in the operations is usually very great.

While we have described our explosives as comprising dynamite' compositions in which. a portion of the nitroglycerin has been replaced by nitrocompounds of the aromatic series, we wish to include not only nitroglycerin itself but liquid nitric esters generally, and particularly those compounds which have been used heretofore as dissolved freezing point depressants of the nitroglycerin, namely ethylene glycol dinitrate, nitrochlorhydrins, nitrated polymerized glycerin, ethyl nitrate, and the like.

While we have described many specific embodiments of our invention in the foregoing, it is tobe understood that we intend to be limited in our invention only as indicated in the following patent claims.

We claim: 1

1. An explosive comprising a liquid nitric ester and at least one nitrocompound of the aromatic series, the relative amounts of said ingredients being so proportioned that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from aNo. 8 cap, said explosive having a crosssectional area of at least about 3 square inches. 2. An explosive comprising a nitroglycerin dynamite in which a portion of the'nitroglycerin inches.

has been replaced by at least one nitrocompound of the aromatic series, the relative amounts of said ingredients being so proportioned thatthe detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from a No. 8 cap, said explosive having a cross-sectional area of at least about 3 square inches. I

3. An explosivaof the straight dynamite type in which a portion of the nitroglycerin has been replaced by at least one nitrocompound of the aromatic series, the relative amounts of said ingredients being so proportioned that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from a No. 8 cap, said explosive having across-sectional area of at least about 3 square inches;

4. An explosive of the a'mmonia dynamite type in which a portion of the nitroglycerinhas been replaced by at least one nitrocompound of the aromatic series, the relative amounts of said ingredients being so proportioned that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from a No. 8 cap, said explosive having a cross-sectional area of at least about 3 square inches.

5. An explosive of the gelatin dynamite type in which a portion of the nitroglycerin has been replaced by at least one nitrocompound of the arcmatic series, the relative amounts of said ingredients being so proportioned that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from a No. 8 cap, said explosive having a cross-sectional area of at least about 3 square 6. A gelatin dynamite comprising nitroglycerin, nitrocotton, ammonium nitrate and at least one nitrocompound of the aromatic series, said nitrocompound being present with the nitroglycerin in such proportions that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that aosares from a No. 8 cap, said explosive having a crosssectional area of at least about 3 square inches.

7. A gelatin dynamite comprising nitroglycerin, nitrocotton, ammonium nitrate and at least one nitrocompound of the aromatic series, the relative amounts of said nitrocompound and nitroglycerin being so proportioned that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from a No. 8 cap, said explosive having a cross-sectional area of at least about 3 square inches.

8. An explosive of the gelatin dynamite type in which a portion of the nitroglycerin has been replaced by a nitrotoluene, the relative amounts of nitrotoluene and nitroglycerin being so proportioned that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from a No. 8 cap, said explosive having a cross-sectional area of at least about 3 square inches.

9. A gelatin-dynamite comprising nitroglycerin, nitrocotton, ammonium nitrate and a dinitrotoluene, said dinitrotoluene being present with the nitroglycerin in such proportions that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from a N0. 8 cap, said explosive having a cross-sectional area of at least about 3 square inches.

10. A gelatin dynamite comprising nitroglycerin, nitrocotton, ammonium nitrate and a'dinitrotoluene, the relative amounts of the dinitrotoluene and the nitroglycerin being so proportioned that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from a No. 8 cap, said explosive having across-sectional area of at least about 3 square inches.

11. A gelatin dynamite comprising between 3 and 10 per cent. nitroglycerin, nitrocotton, ammonium nitrate and at least one nitrocompound of the aromatic series, said nitrocompound being present with the nitroglycerin in such proportions that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from a No. 8 cap, said explosive having a cross-sectional area of at least about 3 square inches.

12. A gelatin dynamite comprising between 3 and 10 per cent. nitroglycerin, nitrocotton, ammonium nitrate and at least one nitrocompound of the aromatic series, the relative amounts of said nitrocompound and nitroglycerin being so proportioned that the detonation of the explosive and its propagation when unconfined requires a detonating impulse greater than that from a No. 8

can, said explosive having a cross-sectional area of at least about 3 square inches.

13. An explosive comprising a, liquid nitric ester, at least one nitrocompound of the aromatic series, and a liquid organic desensitizing agent, substantially soluble in said nitric ester and functioning as -a liquefying agent for the combination of nitric ester and nitrocompound, the relative amounts of nitroglycerin and desensitizing in- Y gradients being so proportioned that the detonation of the explosive and its propagation when unconfined requires a detonating impulse-greater than that from a No. 8 cap, said explosive having a cross-sectional area of at least about 3 square inches.

WILLIAM E. KIRST. CLIFFORD A. WOODBURY.