US2142886A - Explosive and method of producing the same - Google Patents

Description

Patented Jan. 3, 1939 UNITED STATES PATENT OFFICE EXPLOSIVE AND METHOD OF PRODUCING THE SAME No Drawing. Application March 1'7, 1937, Serial No. 131,449

12 Claims.

This invention relates to explosives and methods of producing the same, and particularly to blasting explosives of low density and method of preparation thereof.

5 Heretofore, blasting explosives of low density have been prepared by impregnating a low density carbonaceous material, e. g., finely divided balsa wood, bagasse, or wood pulp, with a solution of ammonium nitrate, or a solution of a mixture of ammonium nitrate and sodium nitrate, and then drying the impregnated material, thus producing an intimate mixture of the oxidizing or explosive salt crystals and the carbonaceous material, and adding to such dry mixture other ingredients com- 15 monly used in blasting explosives, e. g., nitroglycerin, nitroglycol, or the like, if desired. In some cases, the carbonaceous material impregnated with oxidizing or explosive salts has been used as an explosive, without admixture of a liquid sensitizing agent, such as nitroglycerin, but such explosive has suffered from the disadvantage of low sensitiveness to detonation, requiring the use of inordinately large initiating charges or boosters, and leading to incomplete detonation of such explosive.

A further disadvantage of explosives comprising carbonaceous material impregnated with oxidizing or explosive salts is that it is extremely s0 difilcult and dangerous to dry such mixtures from the last traces of moisture, after impregnation by the solution, and such drying has required the use of relatively high temperatures, at which the mixture frequently ignited and caused disastrous explosions.

Attempts have been made to improve such mixtures of impregnated carbonaceous materials and oxidizing or explosive salts, and avoiding the danger in the drying thereof, by utilizing, as the 40 impregnating salt mixture, a mixture of hydrated magnesium nitrate and ammonium nitrate, which mixture, at a relatively low temperature, fuses in its water of crystallization, and such a melt bein used to impregnate the carbonaceous material,

45 the mixture then being cooled, whereupon the water of crystallization returns to the solid state, without the necessity of using high temperatures to drive off water from the mixture.

Such explosives, have, however, suffered from 50 the disadvantage that the water of crystallization contained therein detracted from the explosion,

and produced explosives whose strength was lower than that desired. I

I have found that, by the use of guanidine nitrate as an impregnant of carbonaceous material, I produce low density explosives free from the disadvantages enumerated above.

My invention comprises broadly the impregnation of porous .carbonaceous material with guanidine nitrate either alone or in admixture with one or more suitable nitrates, and the explosive made therefrom. Thus, the guanidine nitrate may be mixed with ammonium nitrate, an alkaline earth metal nitrate such as calcium nitrate, or it may be mixed with ammonium nitrate, and an alkali metal nitrate such as potassium nitrate or sodium nitrate, or the guanidine nitrate may be mixed with an alkaline earth metal nitrate, such as calcium nitrate, and an alkali metal nitrate such as potassium nitrate, sodium nitrate, ammonium nitrate, etc. Where, for example, the guanidine nitrate is used with either calcium nitrate or ammonium nitrate, the admixture may be produced by adding the ingredients which had been separately prepared or if desired the mixture may be synthesized in situ by a suitable chemical reaction as hereinafter explained.

As the carbonaceous ingredient I may use finely divided balsa wood, bagasse, wood pulp, charcoal, and the like. To the carbonaceous material impregnated with, for example, guanidine nitrate and calcium nitrate, I may add suitable quantities of other ingredients commonly used in explosives, such as nitroglycerin, nitroglycol, nitrocellulose, wood pulp, sodium nitrate, ammonium nitrate, flour, chalk, etc., depending upon the type of explosive I desire to prepare.

In the practice of the process according to my invention I may fuse a mixture or an excess of ammonium nitrate and calcium cyanamid, preferably crude calcium cyanamid, to form guanidine nitrate and calcium nitrate in molten condition, and then introduce a suitable quantity of finely divided carbonaceous material into the melt. The carbonaceous material absorbs the fused salt mixture and becomes impregnated therewith. The mixture is allowed to cool, and forms a dry, low density explosive, sensitive to a No. 6 blasting cap.

I may also heat together a mixture of dicyandiamid and excess 'ammoniumnitrate, which react to form guanidine nitrate and ammonium nitrat, and to this fused mixture I may add suitable quantities of carbonaceous materials to absorb the fused salt mixture, then cool the whole, and obtain a dry, low-density explosive, sensitive to a No. 6 blasting cap.

As a specific example of the preparation of my improved low-density explosive, I may take 20 parts by weight 01' crude calcium cyanamid and The mixture fuses, and the components thereof react according to the equation The ammonia evolved during the reaction may be absorbed in water, passed into dilute nitric or sulfuric acid to form the corresponding salt, or otherwise utilized.

To the above melt I then add additional ammonium nitrate until a total of 150 parts by weight thereof has been added, andcontinue the heating at about C. to about C. to render it fluid, and to the molten product I then add about 30 parts by weight of finely divided balsa wood and mix the latter thoroughly with the fused salt mixture. The balsa wood absorbs completely the fused salt mixture to form a moistappearing mixture, which is then cooled to ordinary temperature, forming a dry, crisp, impregnated carbonaceous material, sensitive to detonation by a No. 6 blasting cap, and of high explosive strength, due to the absence of diluting salts, water of crystallization, etc., and due to the high explosive strength of the guanidine nitrate present.

As a further example of the preparation of my improved low-density explosive, I may take 20 parts by weight of dlcyandiamid and 95 parts by weight ofammonium nitrate, and heat the mixture to about 121 C. until the mixture fuses and the reaction proceeds to completion. The reaction involved is that the reactants may be mixed in molecular or.

any other desired proportions. I then add 25 parts by weight of finely divided bagasse, to form a moist-appearing mixture, which is then cooled to ordinary temperature, to form a crisp, dry carbonaceous material impregnated with guanidine nitrate and ammonium nitrate and represents a low density explosive of high strength, due to the absence of diluting salts therein and due to the high explosive strength of the guanidine nitrate content.

As a further example of my improved explosive, I may take calcium cyanamid 80 parts by weight, and ammonium nitrate 636 parts by weight, and heat the mixture to about 95 C., the ammonia formed during the reaction being suitably recovered, if desired. I then add 80 parts by weight of sodium nitrate and raise the temperature of the melt to about 0., or I may heat the melt to a somewhat higher temperature and then allow the temperature of the melt to fall to about 105 C. I then add a mixture of parts by weight of finely divided balsa wood and 120 parts by weight of finely divided bagasse, mix well to impregnate the carbonaceous mate rial with the molten salts, and allow the mixture to cool.- This impregnated material is an explosive, and when packed into a 1%"x8" cartridge will detonate by a No. 6 blasting cap and ropagate explosion over a gap of one inch.

In the above example, I may mix the sodium.

nitrate with the calcium cyanamidand ammonium nitrate and fuse the mixture, then proceeding as described, instead of adding the soaiaasse dium nitrate to the mix after reacting the calcium cyanamid and ammonium nitrate.

As an example of the preparation of dynamites containing carbonaceous material impregnated by my process, I give the following:

Parts by weight Such a dynamite had the advtantage that it withstands storage without appreciable reduction in sensitiveness.

I have found that my improved explosive comprising carbonaceous material impregnated with guanidine nitrate, when tested by the standard gap test in cartridges 1 "x8", detonates over an air gap of 1 inch, whereas explosive made by impregnating carbonaceous material with ammonium nitrate alone fails topropagate detonation over an air gap and propagates only at zero inches, and carbonaceous material impregnated with a mixture of ammonium nitrate and hygrated magnesium nitrate propagates at only zero inches and fails to propagate across an air gap. It will be appreciated that a dynamite having a gap test of only zero inches is unsatisfactory, in that, when fired in a borehole, it tends to fail to propagate from cartridge to cartridge and thus tends to leave unexploded cartridges in the borehole.

A further advantage of my improved explosive is that there may be employed, for its manufacture, very cheap ingredients, such as crude calcium cyanamid, or the relatively cheap d1- cyandiamid, and that during its process of manufacture requires only a moderate heat to fuse the low-melting salts and requires no long-continued heating to evaporate water from the impregnated carbonaceous ingredient, because no water is present at any period in its preparation.

What I claim and desire to protect by Letters Patent is:

1. An explosive including a porous, absorbent, carbonaceous material impregnated with guanidine nitrate.

2. An explosive including a porous, absorbent, carbonaceous material impregnated with a mixture of guanidine nitrate, calcium nitrate and ammonium nitrate.

3. An explosive including nitroglycerin and a porous, absorbent carbonaceous material impregnated with a mixture of guanidine nitrate, calcium nitrate and ammonium nitrate.

4. An explosive including a porous,absorbent, carbonaceous material impregnated with a mixture of guanidine nitrate and ammonium nitrate.

5. Process of producing an explosive comprising heating calcium cyanamid and an excess of ammonium nitrate to form a fused mixture of guanidine nitrate, calcium nitrate and ammonium nitrate, impregnating a porous,,absorbent carbonaceous material with said fused mixture of guanidine nitrate, calcium nitrate and ammonium nitrate, and allowing the impregnated material to cool.

6. Process of producing an explosive comprising heating dicyandiamid and ammonium nitrate to form afused mixture of guanidine nitrate and ammonium nitrate, impregnating a porous, absorbent, carbonaceous material with said fused mixture of guanidine nitrate and am- 7'5 monium nitrate, and allowing the impregnated material to cool.

'7. Process of producing an explosive compris-- ing heating calcium cyanamid and an excess of ammonium nitrate to form a fused mixture of guanidine nitrate, calcium nitrate and ammonium nitrate, and adding thereto sodium nitrate, impregnating a porous, absorbent, carbonaceous material with said fused mixture, and. allowing the impregnated material to cool.

8. An explosive including nitroglycerine and a porous, absorbent, carbonaceous material impregnated with a mixture of guanidine nitrate and ammonium nitrate.

9. An explosive including nitroglycerine and a porous, absorbent, carbonaceous material impregnated with a mixture of guanidine nitrate, calcium nitrate, ammonium nitrate, and sodium nitrate.

10. An explosive which comprises an alkaline earth metal nitrate and a porous, absorbent, carbonaceous material impregnated with guanidine nitrate.

11. An explosive which comprises an alkali metal nitrate and. a porous, absorbent material impregnated with guanidine nitrate.

12. An explosive which comprises an alkaline earth metal nitrate, an alkali metal nitrate, and a porous, absorbent material impregnated with guanidine nitrate.

WILLARD DE C. CRATER.