US2314809A - Explosive composition - Google Patents

Description

atented ar. 23, 1%43 mington, DeL, a corporation of Delaware No Drawing. dpplicationdanuary 7, 1941, Serial No. 373,21

11 Claims.

This invention relates to explosive compositions containing a water-soluble inorganic salt, and more particularly to ammonium nitrate explosives.

This application is a continuation-in-part of my copending applications Serial No.. 288,131, filed August 3, 1939, now Patent Number 2,231,043, and Serial No. 354,825, filed August 30, 1940.

Ammonium nitrate is a very extensively used ingredient in present day high explosives of the dynamite type. It replaces nitroglycerin in increasingly larger proportions for a variety of reasons, particularly because it possesses high explosive strength, has outstanding safetyv properties, and is economically attractive. Ordinarilyit is used with some particular sensitizing agent,

either explosive or non-explosive in nature.

While ammonium nitrate explosives have been used with great success, one disadvantage of this ingredient has always been evident, namely, that it has a great aifinity for water. Because of this fact, there is a tendency for explosive compositions high in ammonium nitrate to become hard and set on storage in the presence of even small amounts of moisture. This brings about a decreased sensitiveness of the explosive and a lesser degree of uniformity in performance. -The water resistance of ammonium nitrate explosives is generally low because of the presence of this very soluble salt.

An object of the present invention is an explosive composition containing at least one watersoluble salt and having improved water resistance. A further object is an ammonium nitrate explosive of enhanced water resistance. A still further object is an explosive containing ammonium nitrate wherein an ingredient is present which tends to prevent the harmful penetration of water. Additional objects will be disclosed as the invention is described more at length hereinaiter.

I have found that the foregoing objects are accomplished by including oat flour as an ingredient in explosive compositions containing at least one water-soluble salt, said oat flour or meal desir ably being included in the explosive composition in pulverulent form and being capable of functioning as a protective agent against water for said salt. By the term oat flour or oatmeal, I intend to designate both the finely divided, untreated meal resulting from the grinding of the cat kernel and the pretreated and preheated material such as is commonly employed as a cereal food. My invention does not include the use of oat hulls, however, except as small amounts may be present fortuitously in the ineal. Oat

,hulls comprise largely the chair and such portions of the whole oats, and do not give the advantageous results desired, whether in coarse or fine condition.

My invention is applicable with advantage to all explosive compositions containing a watersoluble salt, whether this salt is ammonium nitrate,'sodiu.m nitrate, a chlorate or perchlorate, or other soluble salt. I find it particularly important in the case of ammonium nitrate explosives, and especially in such compositions containing an explosive nitric ester, nitroglycerin for example. It should'be understood, however, that the invention is applicable as well to explosive compositions which contain no ingredient which is itself an explosive, for example compositions containing non-explosive sensitizing agents. Many compositions, for instance, contain ammonium nitrate or other oxidizing agents sensitized with materials such as aluminum or other finely divided metals. Likewise, certain ammonium nitrate explosives are sensitized with various forms of carbon, hydrocarbons, and explosive and non-explosive nitrated hydrocarbons, for example charcoal, paraifin, dinitrotoluene, and the like. My invention is equally applicable to these compositions, since they contain the water-soluble salt which must be protected from wet conditions in the field.

The advantages of my invention are illustrated by the following specific embodiments, in which A and B represent ammonia dynamites of similar compositions, A containing ordinary carbonaceous combustibles and B oat flour.

Nitroglycerin .percent. 14. 0 14. 0 Ammonium nitrate.. (10.... 36. 5 36. 6 Calcium stearatc. --do 0. 3 0. 3 Sodium nitrate- -.do. 35. 8 35. 8 Wood pulp .do-- 1.0 1.9 Prior art meals. do..-. 5. 9 Oat flour .do 5.0 Sulfur .do.-.- 6.0 6.0 Chalk do. 0.5 0.5

' 100. 0 100. 0 Densityctgs.l lbs 109 108 W ater lresistance: I

5 hrs The improvement in water resistance, due, to the introduction of oat flour into the explosive, is very striking, as shown in the above examples. The test consisted in immersing the partly opened dynamite cartridge in water in a metal tube for pastes.

I may mention untreated wheat flour, corn meal,"

the time designated, detonation then being attempted by a blasting cap. In the case of the dynamite containing the meals of the prior art,

four failures to detonate resulted after immersion oi'the explosive for 1 hour, whereas, with the dynamite containing oat flour, four successful detonations were obtained after 5 hours immersion.

Additional evidence of the improved water resistance properties was given by the results of a leaching test, under pressure, of cartridges of '4" by dimensions. In each cartridge tested, four holes were made of diameter in the side wall at each end. The cartridges were then subjected to a water pressure of lbs. per square inch for 24 hours. At the end of the test, the dynamite A, containing meals of the prior art, had been reduced to a column of highly wet material, of 3x6%" size. The weight of the cartridge had been reduced by leaching from 2700 to 1473 grams, some of the latter weight being due to the water present. In the case of dynamite B, containing oat flour, only a very small portion had been leached away at the ends, and the weight had increased from 2743 to 3000 grams. The bulk of the composition was capable of propagation of explosion from a blasting cap.

The oat flour, when present in explosives of the type described, is capable of forming a cohesive and protective paste with the more or less dilute solutions produced when water comes in contact with the outer or exposed portions of explosives containing water-soluble salts. 0rdinary flours, meals, and starches do not disperse satisfactorily and do not form protective As examples of these latter materials.

tapioca starch, and the like.

Thedispersions formed by mixture of ordinary vstarch products with relatively small amounts of either water or dilute nitrate solutions, without application of heat, are such that there is a rapid separation of the flour, meal, starch, or the like. Oat flour acts diflerently in that the "*greater part of the material remains colloidally penetration toward the interior of the explosive column. The gelatinous structure-formed also .prevents segregation of liquid or solid ingredients of'the explosive such as would be caused by water penetration and softening of the composition. The cohesive gel or paste also decreases the loss of solid or liquid ingredients from partly opened cartridges by reason of gravity flow. The leaching of soluble salts is likewise lessened by the presence of the paste.

It will be understood that, in order to-obtain the most favorable results, the cat meal or flour should be in finely divided condition. Preferably v said meal should be in a state of subdivision such that the major portion, that is more than 50%,

will pass a 60-mesh screen. Furthermore, the oat flour is desirably included; in the explosive composition in, pulverulent form during the manufacture of the explosive composition, no paste being formed at that time. Ido not intend to be limited to meal of this degree of flne- 75 ness, however. Likewise, I may wish to introduce into the explosive composition a small amount of a water-insoluble metal soap, such as calcium stearate, which will have a protective and coating effect on the ammonium nitrate against water or moisture. The presence of this latter ingredient, together with the Oat flour. gives very beneficial results. The oat flour is eflective, however, without the presence of the water-insoluble soap. Preferably, said oat flour will be used in an amount not greater than 15%. and I find a quantity between 1% and 9% to be advantageous.

It will be understood that I may use a meal made from the entire oat kernel or portions of said kernel which have a higher protein content. or other fractions of the cat. As previously stated, the ground untreated oat flour gives satisfactory results in improving the resistance of explosives containing. water-soluble salts to the penetration of water. I may prefer, however, to use an oat flour or meal that has been given a preheating treatment or other prior treatment that wouldbring about a substantial pregelatinization.

The invention is applicable with great advantage in ammonia dynamites containing ammonium nitrate and nitroglycerin in amounts not exceeding 25%, for example between 3% and 25%. It hasnnportant applications also in the case of compositions containing other high explosive compounds, such as nitro starch, trinitrotoluene, and the like, in the presenceof ammonium nitrate or other water-soluble salt. Furthermore, it is eflect'ive in the case of compositions in which the ammonium nitrate is sensitized by means of parafiin, dinitrotoluene, car: bon, aluminum, other powdered metals and alloys, and many other materials.

The cat flour. according to my invention, hal

been stated to be present preferably in pulverulent form during the manufacture of the explosive, since in this form the meal or flour functions in the peculiarly eflective manner desired in protecting the explosive against water penetration.

My invention has been described in detail in the foregoing. It will be apparent, however, that many variations may be introduced in methods of application or in compositions without departure from the scope of the invention. I intend to be limited therefore only by the following patent claims.

I claim:

1. An explosive composition comprising v a water-soluble inorganic salt selected from..the group consisting of ammonium nitrate. :sodium nitrate, the chlorates and the perchlorates, a sensitizingagent, and cat flour. in pulverulent form.

2. An explosive composition comprising am- :monium nitrate; a.sensitizing agent, and out flour in pulverulent form.

3. An explosive composition comprising ammonium nitrate, an explosive sensitizing agent, and oat flour in pulverulent form.

4. The explosive composition ofclaim 3, wherein the sensitizing agent comprises nitroglycerin.

5. The explosive composition of claim 3, wherein the sensitizing agent comprises an aromatic nitrocomp'ound. 6. An explosive composition comprising ammonium nitrate, a non-explosive sensitizing agent, and oat flour in pulverulent form.

7. The explosive composition of claim 6, wherein the sensitizing agent comprises a carbonaceous material.

8. The explosive coniposition of claim 6, where- 10. The explosive composition of claim 9, in which the oat flour is present in a degree of fineness such that more than 50% thereof will pass a 60-mesh screen.

11. The explosive composition of claim 9, in

' which the oat flour is present in an amount between 1% and. 9%.

CLARENCE H. WINNING.