US1743172A - Low-velocity ammonia dynamite - Google Patents

Description

Patented Jan. 14, 1930 UNIT WILLIAM H. WARD, OF PARKSIDE,

PENNSYLVANIA, ASSIGNOR TO E. I. DU PONT DE NEMOURS & GOMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELA- WARE LOW-VELOCITY AMMONIA DYNAMITE No Drawing.

My invention relates to relatively low velocity ammonia dynamites ranging in strength from about 10% to which are essentially non-inflammable and which may be used for types of work where black powder has been formerly used.

It is a well known fact that black powder by virtue of its low velocity ofdet-onation is well suited for work where a heaving action instead of a shattering efl'ect is desired. For example, black'powder -has been extensively used in the past for dirt, clay or soft rock stripping operations to be followed by steam shovel excavation. Black powder has, however, the very great disadvantage of being extremely inflammable; and the fact, that its low velocity is dependent upon the slow burn ing of its ingredients rather than a detonation, precludes the possibility of eliminating its inflammability. A number of serious and fatal accidents have occurre tion by sparks of black powder.

I have found that, by using varying amounts of relatively coarse ammonium nitrate in combination with small amounts of nitro-glycerine, a series of dynamites can be produced which, when used for blasting, give the same heaving effect as is obtained with black powder but at the same time have the advantage of being essentially non-inflammable. A

In the discussion throughout this specification, as well as in the claims, the terms used have the following meaning 2-- By strength is meant the explosive strength as determined by the ballistic mortar, expressed in terms of the nitro-glycerine content of the straight nitroglycerine dynamite giving the same swing of the ballistic mortar.

By the term liquid explosive I mean to include nitroglycerine or nitrated glycol or mixtures of either of these with nitrated sugars, nitrated polymerized glycerine and nitrated aromatic compounds.

By the term relatively low velocity is meant a velocity of detonation substantially lower than 2000 meters per second as determined by the Dautrich method or with a Mettegang recorder.

(1 due to the igni- Applicationfiled August 14, 1928. Serial No. 657,427.

By relatively coarse ammonium nitrate is meant ammonium nitrate having a fineness such rat the majority of it passes a standard 10 mesh screen but is held on a standard 60 mesh screen. For example, a typical sample will have a fineness such that not more than 5% is held on a standard 10 mesh sieve and not over 20% passes a standard 60 mesh sieve. In these explosives I may, however, use ammonium nitrate of a fineness such that not over 5% passes a 60 mesh screen in order to vary the velocity of detonation if desired. "Referring to these low velocity blasting explosives, I wish to point out that the liquid explosive content is held between about 4% and 7 in order to reduce the infiammability, the amount used being sufiicient for propagating the wave of detonation. The strength is varied by the use of varying percentages of relatively coarse ammonium nitrate from about 10% to 75%.

In my new powders, I have gone farther than has heretofore been considered possible in reducing the nitroglycerine content without encountering insensitiveness in ammonium nitrate compositions of the character described. WVhile my new dynamites are capable of being detonated with a standard No. 6 blasting cap, the best results are obtained if a primer of any standard dynamite, such as l0% straight or 40% low freezing ammonia dynamite is used.

The following illustrates the composition of my 20% dynamite, in particular, which has been used commercially with success for stripping operations where black powder was formerly used.

v Per cent Grade A Nitroglycerine or other liquid explosive 4-7 Relatively coarse ammonium nitrate- 23-27 NaNO and combustible (sulphur,

impart good free running qualities to bulk packed powder which facilitates loading bore the other hand the explosive ac holes, but on tion of my dynamite is not materiaIly-aflect-, ed if fine meals are used and the dynamite is cartridged.

By my invention- I have produced awsubstantial improvement over black powder in safety, for my new dynamite is essentially non-inflammable.v For example, extensive tests on my grade as well as onoth'er- .grades have shown that they cannot be ignited from a spark, from the spit of a fuse or from a glowing ember.

I claim 1. Blasting explosives of relatively low velocity, ranging in strength from about 10% to 60% and containing from about 4% to 7% of nitroglycerine, most of the balance of the explosive strength being contributed by relatively coarse ammonium nitrate.

2. Blasting explosives of relatively lowvelocity, ranging in strength from about 10% to 60%, containing from about 4% to 7% of liquid explosive and from about 10% to 75% relatively coarse ammonium nitrate.

3. Blasting explosives of relatively low velocity, ranging in strength from about 10% to 60%, containing from about 4% to 7% of liquid explosive and from about 10% to 75% of relatively coarse ammonium nitrate, the remainder comprising sodium nitrate and non-explosive combustible material.

4. Blasting explosives having a velocity of detonation less than 2000 m./sec., ranging in strengthfrom about 10% to 60% and containing from about 4% to 7 \l'quid explo- "containing from about 4% to 7% I ontaining from about 4% to.7%

to 27 of rel-' havinga velocity der comprising sodium nitrate and non-explosive combustible material.

7. A blasting explosive of 20% strength, less than 2000 m./sec., con taining' from about 4% to 7% of liquid explosive comprising nitroglycerine and from about 23% monium nitrate.

,8. Blasting explosive of relatively low velocity ranging in strength from about 10% to 60%, containing from about 4% to 7% pf liquid explosive, and from about 10% to not more than 5% thereof is held on a standard 10 mesh screen and not more than 20% passes a standard 60 mesh screen.

9. A blasting explosive of 20% strength, containing from about 4 to 7% of a-liquid explosive comprising nitroglycerine, and

from about 23 to 27 "of ammonium nitrate to 27% of relativelycoarse amof ammonium nitrate so subdivided that so subdivided that not more than 5 thereof is held on a standard 10 mesh screen and not more than 20% passes a standard 60 mesh screen. v 3

10. A non -infiammable, free-running, blasting explosive having a velocity lower than2000 meters per second, and a strength of about 20%, containing from 4% to 7% nitroglycerine and 23% to27% of relatively coarse ammonium nitrate.

11. A non-inflammable, free-running explosive containing from4% to 7% nitroglycerine and from 10% to'75% of relatively coarse ammonium nitrate.

' 12. A non-inflammable, free-running explosive having a Velocity less than 2000 meters per second, a strength of from 10% to 60%, and containing from 4% to 7% nitroglycerine, sive strength being contributed coarse ammonium nitrate; p In testimony whereof I'afiix my signature.

' WILLIAM H. WARD.

by relatively most of the balance of the explo-" lll