US1963627A - Explosive composition - Google Patents

Description

Patented June 19, 1934 r-ran sTEs EXPLOSIVE COIWPOSITION Harold A. Lewis, Woodbury, N. J., and Clifford A. Woodbury, Media, Pa., assignors to E. I. du

Pont de Ncmours & Company, DeL, a corporation of Delaware Wilmington,

No Drawing. Application April 2, 1932, Serial No. 602,809

14 Claims.

This invention relates to an improvement in explosive compositions having a liquid explosive ingredient as a sensitizing agent, and in particular to a composition of the permissible type com- 5 prising as an ingredient a carbonaceous combustible material consisting of a treated cereal grain which has previously been expanded by subjection to high pressure and subsequent sudden release of said pressure.

The advantages of low density dynamites have become very great in recent years particularly for the blasting of materials having relatively low resistance. By means of these low density compositions the strength of the explosive is well distributed thus preventing unnecessary shattering of the material to be blasted. These and many other advantages of low density dynamites of various types are clearly described in the prior art. Heretofore the more desirable types of these low density dynamites have been produced by means of various carbonaceous combustible ingredients principal among which have been ba gasse pith, balsa wood, ground cornstalks, etc.

An object of this invention is a low density dynamite containing as an ingredient an improved combustible material. A further object is to provide a low density dynamite of improved sensitiveness properties over prior art compositions by means of a combustible ingredient having relatively low absorbent properties for liquid explosive materials. A still further object of our invention is an explosive composition containing as an ingredient a treatedcereal grain which has been previously expanded bysubjection to high pressure and subsequent sudden release of said pressure. description proceeds.

These objects have been accomplished by the following invention in which 'wehave found that a very desirable explosive may be made by means of certain treated cereal grains which have been artificially expanded or puffed, and particularly that form expanded by subjection to high external and internal pressure and subsequent sudden release of saidtpressure.

We have found furthermore that various cereal grains which lend themselves readily to this K treatment will accomplish our purpose such for example as wheat, rice, etc. Various methods may be used to accomplish this treatment but in any case the cereal grain remains intact except that it is'considerably enlarged and the material thereof has been changed greatly indensity. In such treatment the pressure applied from without permeates the material of the grain and when Other objects will appear as the the external pressure is released the pressure within the grain walls causes the explosion or pufiing of the grain kernel, thus resulting in a light, 'fluflfy material. In order to convert this material into suitable form for our purpose the 90 expanded cereal grains are ground, crushed, or otherwise disintegrated so as to make the material readily combustible in explosive compositions. We prefer, however, to cut the material to obtain the proper form, in order not to destroy the low density properties existing in the original pufied grain.

Material of a suitable size for our purpose may be obtained if care is taken that the grain particles are not too small in size. We have found that 79 a suitable material has preferably a size such that a major portion will pass a 6-mesh screen'and at the same time be held on a ISO-mesh screen.

U. S. Patent 1,687,023 to N. G. Johnson and S. G. Baker covers an explosive composition containing as a combustible ingredient ground popped corn. The distinction between that patent and the present invention will at once be apparent, the present material comprising an expanded grain which derives its expandedcondi- 80 tion by the application of high pressure of a vapor, such as steam, and the sudden release of this pressure.

This explosive ingredient according to our invention hasa'density varying betwen 0.09 and 0.15 5 depending on the method of treating the cereal grains. Dynamitecompositions containing this ingredient have superior properties over compositions containing other ingredients of equally low density. The finished explosive compositions containing this pufi'ed cereal material are not only low in density but have excellent sensitiveness qualities by reas n of the combustible material having low absorption properties for nitroglycerin or other liquid explosive ingredient or in gredients.

Our invention is applicable to all non-gelatinous types of dynamite compositions. The three main classes are commonly known' as straight dynamites, ammonia or extra dynamites, and permissible dynamites. The straight dynamites are produced in strengths varying from about 20 to 75% and are used in blasting work where high velocity and sensitiveness to detonation are essential. They ordinarily comprise a liquid explosive ingredient equal in percentage to their grade strength, combustible absorbents and sodium nitrate. The ammonia dynamites are likewise made in several strengths and are used for general blasting. They comprise a lower percentage of liquid explosive than he strai ht dy= namites-of similar grade and contain also ammonium nitrate, sodium nitrate and combustible absorbents. The 29% ammonia dynamite, for example, may contain to of liquid explosive and 8 to 15% ammonium nitrate, while the 60% ammonia dynamite may have 15 to 30% of liquid explosive and to ammonium nitrate. The permissible dynamites are ordinarily of high grade strength, from 40 to and are intended for use in coal mines where there is danger of explosion from mine gases and coal dust; These contain relatively low percentages of liquid explosives, ordinarily between 8 and 15% and relatively high percentages of ammonium nitrate, 60 to combustible absorbents, and in many cases inorganic salts for the purpose of reducing the flame temperature, sodium chloride or sodium nitrate for example.

The following examples are given to further illustrate the foregoing explosives but the invention is applicable equally well. to many difierent types of explosives as will be apparent.

In addition to the improvement in other properties, the low density efiect of the use of our 7 new combustible ingredient is shown by the fact that it makes possible the production of straight and aonia dynamites on otherwise standard formulas, weighing less than 181 grams per 1 x 8" cartridge against a weight of 210 to 220 grams previously obtained. Similarly with dynamites of the permissible type, with the new ingredient, weights of 1%, x 8" cartridges less than 146 grams may be obtained, much lower densities being possible with complete utilization of the treated expanded cereal grains.

It be'understood of course thatwe may vary widely the percentages of ingredients shown in the examples given and may introduce additional ingredients without departing from the spirit of the invention. We prefer, however, to use an amount of treated cereal grain varying between 1 and 20%, since less than 1% of this material will not have the desired efiect on the density, while more than 20% will be undesirable because of the efiect on the sensitiveness of the powder. The exact amount of our treated cereal product for use will depend on the propertions of the other ingredients present in the dynamite and on the density and other properties desired. Preferably, not less. than 5% of nitroglycerin will be incorporated in my improved explosive composition, since a smaller amount than this will not have the desired sensitizing efi'ect. We may use in place of nitroglycerin, for example, solutions in nitroglycerin of various materials commonly considered as freezing point depressants, nitroglycol, nitrated polymerized glycerin, nitrated sugars, nitrocompounds, etc. The amount of. sodium nitrate may likewise be increased or decreased as desired, or omitted entirely, in which case sodium' chloride or other flame suppressing material may be used. Similarly, we may use, together with the treated pufied cereal grain, high density combustible materials such as cornmeal, ivory nut meal, flour,

eeaear etc., or other low density carbonaceous materiais, such as bagasse pith, ground cornstalks, etc.

It is therefore to be understood'that-we are to particles of .pufied cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same.

2. An explosive composition characterized by low density which comprises nitroglycerin as sensitizing agent, anda low density combustible ingredient comprising comminuted particles of pufied cereal grain, the structure of whose starch granules has been disrupted substantially throughoutthe mass of the same.

3. An explosive composition characterized by low density, which comprises more than 5% of a liquid explosive ingredient as sensitizing agent, and a low density, combustible ingredient comprising comminuted particles of pufied cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same.

4. An explosive composition characterized by low density, which comprises a liquid explosive ingredient as sensitizing agent, and at least 1% of a low density, combustible ingredient comprising comminuted particles of pufied cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same.

5. An explosive composition of the permissible type characterized by low density which comprises a liquid explosive ingredient, ammoni nitrate, a non-explosive salt adapted to reduce 115 flame temperature, and a low density combustible ingredient comprising comminuted particles of" pufied cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same.

6. An explosive composition of the peble type characterized by low density, whlchcomprises a liquid explosive ingredient, onium nitrate, a non-explosive salt adapted to reduce flame temperature, and a low density, combustible ingredient comprising comminuted particles of puffed cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same, said composb tion having a density such that a 1% x 8" car= tridge weighs less than 146 grams.

'7. An explosive composition of the straight dynamite type characterized by low density, my... comprises a liquid explosive ingredient, sodium nitrate, and a low density, combustible ingredient comprising commlnuted particles of pufied cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same. 8. An explosive composition of the straight dynamite type characterized by low density which comprises a liquid explosive ingredient, sodium nitrate, and a low density combustible ingredi- 'ent comprising comminuted particles of prided cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same, said composition having a density such that a 1 x 8" cartridge weighs less than 181 grams.

9. An explosive composition of the are whinh dynamite type characterized by low density, which comprises a liquid explosive ingredient, ammonium nitrate, sodium nitrate, and a low density, combustible ingredient comprising comminuted particles of puffed cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same.

10. An explosive composition of the ammonia dynamite type characterized by low density, which comprises a liquid explosive ingredient as sensitizing agent, ammonium nitrate, sodium nitrate, and a low density, combustible ingredient comprising comminuted particles of puffed cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same, said composition having adensity such that a 1 /4 x 8" cartridge weighs less than 181 grams. V

11. An explosive composition characterized b low density which comprises a liquid explosive ingredient as sensitizing agent, and 1 to 20% of a low density combustible ingredient comprising comminuted particles of puffed cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same.

12. An explosive composition characterized by low density, which comprises more than 5% of a liquid explosive ingredient as sensitizing agent,

and at least 1% of a low density, combustible ingredient comprising comminuted particles of puffed cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same, said composition having a density such that a 1%" x 8" cartridge weighs less than 181 grams.

13. An explosive composition characterized by low density, which comprises nitroglycerin as a sensitizing agent, and a low density, combustible ingredient comprising comminuted particles of puffed cereal grain, the structure of whose starch granules has been disruptedsubstantially throughout the mass of the same, said cereal grain being present in the explosive in such degree of fineness that more than 50% of the material will pass a G-mesh and be retained on a GO-mesh screen.-

14. An explosive composition characterized by its low density, which comprises a liquid explosive ingredient and 1 to 20% of a low density, combustible ingredient comprising comminuted particles of pufied cereal grain, the structure of whose starch granules has been disrupted substantially throughout the mass of the same, said cereal grain being present in the explosive in such degree of fineness that more than 50% of said grain will pass a G-mesh screen and be retained on a BO-mesh screen.

HAROLD A. LEWIS. CLIFFORD A. WOODBURY.