US1987295A - Commercial blasting explosive - Google Patents

Description

Patented Jan. 8, 1935 UNITED STATES PATENT OFFICE Atlas Powder Company, W corporation of Delaware No Drawing. Application 11, Del., a

sci-m. No. aim-1': 3 01am. (01. 52-10) My invention is concerned solely with commercial blasting explosives of the propulsive, rather than detonating, type which contain sodi-' James E. Slusser, Serial No. 532,341. The word intended above is used advisedly, because cartridges may contain smaller particles resultant from accidental breakage or erosion and yet be within the scope of my invention.

An important object of my invention is an in- I crease in strength of explosivesas described without material increase in burning speed. In fact, in usual application of the invention the theo-- retical situation indicates no increase or evena decrease in burning speed. Incidental objects are the accomplishment of the increased strength in an economical manner, without increased hazard, and by means of a material that is plentiful and continued supply. I The Slusser application above referred to discloses a molded black powder, wherein the body of powder is in such form and size as to bring about very advantageous results.

So-called pellet blasting powder is a comparatively new development insofar as the United States is concerned and the Slusser molded powder is a very recent development insofar as the entire world is concerned. Bothtypes have in-, volved many new factors of manufacture, properties, application and economy as compared with the old, conventional grain' blasting powder.

uct as described in the patent application of Very important among the new factors are those May 18,1933,

of black blasting powder, and of military explosives of a somewhat analogous composition. For example, the prior art "has proposed the admixture of finished grains of colloided nitrocellulose with finished grains of black blasting pow- 5 der. Such a procedure would be obviously usually unsatisfactory and uneconomical for my purpose for various reasons, among which are that my powder may never exist in grain form and desirably should avoid the extra operations of dry- 10 ing and blending finished individual grains before proceeding to the operations of forming my hardened masses of above prescribed sizes. Further the prior art suggests mixtures of uncolloided, merely nitrated cellulose with military black'powder. To follow this procedure would be entirely uneconomical for my purpose because merely nitrated cellulose is always a primary and never a waste or salvage product and especially because it would defeat my primary object of strength increase without speed increase. Uncolloided nitrocellulose will increase the speed of black powder up to, under certain conditions of amount and type of admixture, even a detonating effect. Also, uncolloided nitrocellulose could not be introduced economically to my powders without greatly increased hazard. Further, it has been proposed to. increase the strength of black powder by the introduction of ammonium nitrate. The proposed perchlorates increase hygro-. scopicity, burning speed, hazard and cost.

Accordingly, my investigations and experiments convinced me that in no prior art were there satisfactory meansv for increasing the strength of my new types of commercial blasting 35 powder consistent with economy, safety, manufacturing convenience and accomplishment of desired powder quality and blasting efiects.

It is well known that there are, annually, relatively large quantities of smokeless powder- 40 colloided nitrocellulose-rejected as unfit for further military use. Some forms are colloided by means of non-explosive solvents as ether-alcohol; others by means of explosive solvents as nitrogly'cerine. These rejected powders may, at times, be obtained at very low cost. I

Specifically, my invention consists in the application of colloided nitrocellulose, as distinguished -from merely nitrated cellulose or nitrocellulose applied in liquid solution in a solvent, to commercial blasting powder of structure, composition and particle size previously described, in a manner to produce an important strength increase economically, conveniently and without increased burning speed and hazard. It

also includes the product resulting from the foregoing practice. My preferred method of manufacture involves no addition to standard equipment at mills manufacturing the types of powder concerned.

That there may be no question regarding the.

theory of my invention I will explain as follows before discussing the detailed application of the same. It is well known that colloided nitrocellulose functions in an entirely different manner from merely nitrated cellulose and obviously is the only form of nitrocellulose that is practical for the practice of my invention which is the development of new forms of blasting powder of greatly increased strength without increase in burning speed; in other words, the desirable form of strength increase resultant from increased gas volume, rather than the usually undesirable form of seaming, but not actual, strength increase resultant from speed of burning increases which do not effect an actual increase of total strength, but merely a more rapid gas evolution with the consequently greater disintegrating action, which is undesirable for most applications of blasting powder. -It is obviously within the scope of my invention to blend the colloided nitrocellulose by any preferred mechanical method to any preferred final product I with the normal blasting powder ingredients within the limits previously cited, since there is, in no case, a chemical reaction during fabrication, but a mere mechanical mixture, whatever the original and final status of the individual ingredient particles and whatever the mixing and drying methods.

In practice, I may proceed as follows: Assume wheel mill incorporators of a capacity of 500 lbs. of powder and a wish to use 10% of my strengthening addition. I place 50 lbs. of wet colloided nitrocellulose in any form in the incorporator and run the wheels on it until it is of the desired particle size for the particular purpose then involved. I may immediately add the composition containing sodium nitrate, carbon and sulphur of any preferred moisture content and continue the wheeling operation. Water may be allowed to decrease by evaporation or increase, by addition, at will. The time of wheeling is incidental, dependent upon the grade of final product immediately sought. The product from the incorporation may be packed into molds, re-

moved therefrom, dried and wrapped or in-- serted into the ultimate cartridge containers or it may be immediately packed in the ultimate containers and dried therein. These ultimate containers may be simple paper wrappers or tubes as disclosed in the Slusser application. Where a low density, highly aerated product is desired, which indicates that packing intensity would be low and the molded product of insufficient mechanical stability to stand removal from molds and drying without breaking up, I prefer the second procedure. In the former case, intensity of pressing inthe molds is the principal factor in a hard, permanently formed final product. In the latter case, crystallization of the water soluble content of the powder is the important factor in reaching an equivalent result, indicating that a higher moisture content in the powder is preferable in the lattercase. I

It will be obvious that, in. either case, the incorporator product may be subjected to any desired change in physicalcondition. such as graining, prior to molding. It will also be obvious that my colloidednitrocellulose may be partially wide range.

or wholly preprepared as to structure before going under the wheels or may be mixed with the other ingredients prior to, during or after wheeling. It is equally obvious that the nature of the incorporator may be varied and other conditions may be varied to suit. The amount of colloided nitrocellulose used is dependent entirely upon the desired strength of the ultimate product. Generally, an addition of 10% colloided nitrocellulose will increase the strength of the ultimate product by about one-third as compared with the same product without the colloided nitrocellulose.

In the field of the old, conventional grain blasting powder it was possible to vary the blasting action by variation in grain size through a This was not resultant from an increase in total strength, but a mere change in time of gas evolution from the powder. The new forms of molded blasting powder present no such capacity for adjustment to particular conditions. Consequently, it has not been possible to vary theblasting actions of these new forms to suit the coal, for instance, that is to be quence because the grades by testare very fre-.

quently found to overlap one another, or to approach one another so closely that there is no practical difference. Expedients used in eiforts to vary the characteristics of pellet powders have been varied wheeling or incorporating times, varied physical conditions of the individual ingredients prior to wheeling, various particle sizes and moisture contents prior to molding, varied molding pressures and varied degrees of aeration in every case ultimate results being uncertain to a high degree and the procedures costly and troublesome.

My invention permits of one systematic operating procedure, the only required variable being the amount of colloided nitrocellulose added and the desired result is definitely predictable and assured, just as in the field of high explosives the result may be assured by the nitroglycerin content added.

' While theories, practices, preferred forms and limiting specifications have been given by way of examples, explanations and clarifying statements, it will be apparent that variations within -the scope of the disclosures and attached claims are part of my invention. From about two per cent to about 20 percent colloided nitrocellulose is the practical range.

Colloided nitrocellulose in grain or particle form is an obvious material to those skilled in the art, but definition by examples is given so that clarification may b complete. The product is instanced by smokeless powder or picture film. As a matter of economy, salvaged scrap or "breakdown" material is usually used in my process.

Having described my invention, what I claim A commercial blasting unit in mass form composedof a mixture of black powder constitin the black powder constituents materially preclosing the particles of colloided nitrocellulose.

2. A commercial blasting unit in mass form of not lessvthan one inch in length and .7 inch in di wants and colloided nitrocellulose material wherewith each other in such manner as to form a uniform, homogeneous mixture in which the par-' ticles of the several ingredients are in close and substantially uniform contact throughout the mass, with the black \powder constituents embracing and enclosing the particles of colloided nitrocellulose.

3. The herein described process of preparing commercial blasting powder in mass form, which consists of molding together under at least some pressure a wetmass or black powder constituents and colloided nitrocellulose with the black powparticles. 7

ameter, composed of a mixture of black powder constituents in materially preponderating der constituents and colloided nitrocellulose quantity whereby the latter constituents 'are wherein the black powder constituents materially caused to embrace the colloided nitrocellulose 15 preponderate in quantity and wherein the particles of the respective ingredients are blended