US1992189A

US1992189A - Gelatin dynamite composition

Info

Publication number: US1992189A
Application number: US619126A
Authority: US
Inventors: Fred F Chapman
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1932-06-24
Filing date: 1932-06-24
Publication date: 1935-02-26
Anticipated expiration: 1952-02-26

Description

Patented Feb. 26, .1935

1,992,189 eata'rm nxrremrn eoosrrrom' Fred r. Chapman, Wilmington,

E. I. du Pont de Nemours & mington, Bet,

Bet, assignor to Company, Wila corporation of Delaware No Drawing. Application June 24,

- Serial No. 619,126

9 Claims. (CI. 52-13) This invention relates, in general, to gelatin dynamites having improved explosive properties and, more particularly, to gelatin dynamites which exhibit superior sensitiveness and propa- 5 gating properties after long periods of storage mally liquid explosive ingredients. Some form and under adverse conditions of use.

The class of high explosives usually termed gelatin dynamites is characterized by the fact that at least one ofthe ingredients is soluble in, and greatly increases thevisoosity of, the norof nitrocellulose, preferably nitrocotton, is ordinarily used as the gelatinizing material, and this is mixed with nitroglycerin, nitroglycol, and the like, or with mixtures of similar nitrated aliphatic alcohols with nitrated aromatic hydrocarbons suchas trinitrotoluene or dinitrotoluene in the proper proportions to produce a viscous, plastic, and cohesive mass. Explosive properties such as strength and gaseous products of combustion' are modified and adjusted by addition of suitable oxidizing agents and carbonaceous combustibles to the above-mentioned plastic mass.

By the term gelatin dynamites, as referred to herein, is meant those explosives which contain a relatively high proportion, by volume, of gelatinized liquid explosive and are usually cartridged by an extrusion process. These are differentiated from the class of high explosives known as semi-gelatins, by the fact that the latter contain arelatively low proportion, by volume, of gelatinized liquid explosive and are not adapted to' cartridging by the existing extrusion processes.

The usual commercial gelatin dynamites vary in grade strength, from 20% to 90%, depending upon the explosive content. These grades also vary in density, for example, from 1.70 for the low grades to-as low as 1.60 for the grades, and even lower than this-figure for the grade.

The sensitiveness, or propagating power of gelatin dynamites varies notably, depending on the composition and grade, and also to a marked degree on the density of the explosive; the higher the density, the lower the propagating power, other things being equal. The propagating power of gelatin dynamites decreases with age because of a gradual increase in density,-this increase being due to theloss of small air bubbles entrapped in the gelatins at the time of manufacture. Furthermore, in deep oil wells and in submarine blasting, where the explosive is subjected to considerable external pressure, the

density of the gelatin explosive is increased and its propagating power materially decreased.

It is quite common in the case of relatively deep submarine blasting, for thegelatin to be so adversely affected by the water pressure that it fails to propagate completely, or that a portion of the charge burns, thereby failing to properly blast the rock, thus making it necessary to re-shoot after the dredge has cleaned up the area blasted.

This invention has as an object the production of gelatin dynamites having substantially lower initial densities than have heretofore been practicable. A further object is the production of gelatin dynamites which will maintain low densities and satisfactory sensitiveness and propagating power, over long periods of time, under either atmospheric or greater than atmospheric pressures, and dynamites which are superior to gelatins heretofore manufactured for use in oil or gas well, and in general submarine blasting. Other objects will appear as the invention is further described.

I have found that these objects may be accomplished by the use of low density vegetable piths, in place of wood flour, starch, ivory nut meal, or the like, which comprise the carbonaceous combustibles now most commonly used.

My invention comprises,'broadly, the use in gelatin dynamite of low density vegetable piths.

By the term vegetable piths is meant the product obtained by separation of the pithy portion of suitable plants from the outer covering of high density material.

I have found, for example, that the pith of sugar cane (commonly termed bagasse pith) constitutes a very desirable material for the purposes oi my invention. Bagasse pith is usually obtained from sugar cane, after extraction of the sugar, by screening out the major portion of the long fibers, leaving substantially pure pith.

Small percentages of the fibers are not objectionable and do not interfere with securingthe desired results, but the pith as used in my invention should preferably not contain over 25% of fiber. Other methods of separating pith from fiber such as, for example elutriation byameans of air or water, are well known in the art and may be utilized in obtaining bagasse pith of properties which .are satisfactory for use in my invention.

The product obtained by any of the above mentioned processes consists imia very finely divided material having a distinctly cellular structure. By certain modifications in the preparation of v the subsequent This material may be prepared by the following method. The corn stalks, preferably welldried in advance, may be stripped of their leaves and distintegrated by rasping, for example, against a metallic wheel containing relatively small teeth on its periphery. The finely divided material thus obtained may be passed through a screen, for example, one containing six meshes per linear inch.

Various amounts of relatively high density fibrous material may be present in corn stalk pith prepared by the method described in the foregoing. While not essential, it may be desirable to remove a substantial proportion of the fibrous material. This may be accomplished by any one of several processes well known in the art, for example, by an elutriation process, preferably using air as the classifying medium.

While I have found that all pithy materials, similar to those described in the foregoing, are relatively low in density, I prefer to use those which, in' the form of particles passing a sixmesh screen, have a density between 0.1 and 0.3, preferably less than 0.2. It should be mentioned that the densities referred to are those obtained while the material is under 25 pounds per square inch pressure. Although only two types of vegetable pith have been described, it will now be apparent that various equivalent materials for my' purpose are available which may be used without departure from the spirit of my invention. As examples, I various varieties of sunflower stalks, including Jerusalem artichokes, etc.

In order to obtain lower densities than those occurring in the natural product, I may use one of the several treating processes which are well known in the art. Described briefly, such a treating process may consist in steaming the pith with a sbstantial proportion of water, whereby the cellular structure is expanded and a lowering in density results. A further treating process, which may find use in the prepara-. tion of vegetable piths for use according to my invention, consists in-treating with high external and internal pressures with sudden release of said pressures. This process results in a substantial expansion of the cellular structure with consequent lowering in density.-

While not essential, it is preferable that all of the materials described in the foregoing should be dried to a reasonable moisture content before use.

My invention is applicable to all types of gelatin dynamites. The three main classes of the gelatin dynamites are commonly known as straight gelatins, ammonia gelatins, and permissible gelatins. The straight gelatins range in strength, according to the usual terminology, from 20% to 100%. The latter is commonly known as blasting gelatin. Straight gelatins ordinarily contain a gelatinized liquid explosive ingredient, with varyingproportions of sodium nitrate and carbonaceous combustibles, depending cite the pith of corn cobs,

the pithy materialon the strength and other properties which may be required.

The ammonia gelatins usually contain a smaller proportion of gelatinized liquid explosive than grade strength, the

straight gelatins of the. same strength being made up by the use of ammonium nitrate. Permissible gelatins may be of either the straight or the ammonia type, with the addition of a safety ingredient which permits their safe use in coal mines where there is danger of explosion from mine gas or coal dust.

While my invention is applicable to many different forms-of gelatin dynamite, the following examples are given to illustrate its applicability to each of the commontypes of gelatin dynamite composition described in the foregoing.

Type gelatin ingredient Straight Ammonia Permissible Per ce'n Per cent Per cent N itroglycerin 50. 60. 0 30. Dinitroto1uene. 3. 2. Nitrocott0n.- 2. 6 2. 3 0. Sodium nitrate 36. 6 2. 2 44. Ammonium nitrat 24.0 Ammonium chloride 15.0 Vegetable pith. 4 0 6.0 2.0 Star 5 l 1.0 4. 5 Chalk l 7 1.0 1.0

As illustrative of the .value of my invention,

there is given below a comparison of the formulas and properties of a standard 60% straight gelatin (A) with those of a representative 60% straight gelatin (B), containing one of my low density vegetable pithproducts. It will also be seen from the following table that a greatly improved product in this class of explosives is obtained which not only has a higher sensitive-- 'ness at the time of manufacture but retains these properties during storage.

Nitroglycerin 50.0 50. Nitroc n 2. 6 2. Sodium nitrate 36. 6 36. Wood pulp (dens.-0.247) 7.0 Bagasse pith (dens.-0.165) 4. Star l. 6 4. Ivory nut meal 0. 5 1.

alkl. 7 1. Cartridges 96 101 Density after 1 day's storage 1.601 1.538 Density after 1 months storage at 100 1. 662 l. 566 Sensitiveness after 1 day's storage 10' Sensitiveness after 1 month's storage at 100 F- 3' 15' It is apparent that the extent of the density decreases, which may be obtained through the use of low density vegetable piths, willbe largely dependent on the' amount of such material it is desirable to use. From a practical standpoint, however, the amounts are limited by the extrudability of the gelatin and the undesirable effects on properties involved in the use of too high percentages of carbonaceous combustibles. Preferably, I use between 0.5% and 15% of the low density vegetable piths, although my invention contemplates the use of between 2% and 10% of these materials as most satisfactory.

It would ordinarily be expected that the incorporation of these vegetable piths and like materials in gelatins would result in a product that would stiffen, or harden, particularly upon storage. On the contrary, the process of manufacture of the gelatin type of dynamite is not only improved, for the .reason that the incorporation of these materials in gelatins results in a product that is more easily worked in the various steps of the process, particularly in the extruding, cartridging and packing operations, but the finished product can be shipped into and stored in hot climates without the loss 01 plasticity of the product.

It-will be understood, of course, that the percentage of ingredients given in the foregoing examples may be varied within wide limits, and that additional ingredients may be introduced without departure from the spirit of my invention. It is also to be understood that I do not limit myself to the use of vegetable pith as the sole combustible material, either high or low density, inasmuch as certain properties of other combustibles may cause their use to be of advantage. I may also use in place of all or part of the nitroglycerin, for example, nitroglycol, nitrated polymerized glycerin, nitrated sugars, nitrated aromatic hydrocarbons, etc.

It will be apparent from the foregoing that many variations of my invention exist and may be practiced within the scope thereof and for this reason I do not intend to be limited except as indicated in the following pater t claims:

I claim:

1. A low density gelatin dynamite comprising a gelatinized liquid explosive and a vegetable pith. 2. A low density gelatin dynamite comprising a gelatinizecl liquid explosive and bagasse pith.

3. A gelatin dynamite comprising a gelatinlzed liquid explosive and the pith of corn stalks.

4. A gelatin dynamite comprising a gelatinized liquid explosive and the pith of sunflower stalks.

5. A gelatin dynamite comprising a gelatinized liquid explosive and the pith of sunflower stalks of the variety known as Jerusalem artichokes.

6. A gelatin dynamite comprising as ingredients a gelatinized liquid explosive and a vegetable pith ,which, in the form of particles passing a G-mesh screen; has a density not greater than 0.3.

' 7. A low density gelatin dynamite comprising a, liquid explosive ingredient, nitrocellulose, and from 0.5% to 15% of a vegetable pith.

8. A gelatin dynamite, characterized by its relatively low density, nitroglycerin, nitrocotton, and bagasse pith, said. bagasse pith having a density between 0.1 and 0.3.

9. A gelatin dynamite, characterized by its relatively low density, containing as ingredients nitroglycerin, nitrocotton, one or more inorganic oxidizing materials, carbonaceous combustible materials, and bagasse pith in the amount 'of 0.5% to 15%.

containing as ingredients