US2867518A - Detonator compositions - Google Patents

Description

DETONATOR COMPOSITIONS David T. Zebree, Kingston, N. Y., assignor to Hercules Powder Company, Wilmington, Del., a corporation of Delaware No Drawing. Application December 31, 1956 Serial No. 631,469

Claims. (Cl. 52-2) This invention relates to initiator compositions. In one aspect this invention relates to lead-tellurium compositions, containing fatty acid salts, as blasting initiators. In another aspect this invention relates to lead-tellurium compositions, containing fatty acid salts, particularly suitable as ignition mixtures in electric blasting caps. In still another aspect this invention relates to leadtellurium-fatty acid salt compositions as ignition materials and containing selected additives for the regulation of their fuse ignitability characteristics when employed as igniters in delay caps.

Blasting cap charges comprise generally a 'base charge of a detonating explosive such as pentaerythritol tetranitrate, a heat-sensitive primer charge such as diazodinitrophenol, mercury fulminate or lead azide superposed on the base charge, and a readily ignitable ignition charge capable of firing the primer charge by the heat generated. In the case of delay caps an additional slow burning composition or delay fuse is generally included between the ignition and primer charges and exhibits such a predetermined rate of burning that the specified time interval elapses between the application of the firing current and the explosion of the primer charge.

This invention is concerned with new blasting initiator compositions advantageously applied as ignition charges in electric blasting caps. The said charges are also applicable as delay fuses in certain applications.

An object of this invention is to provide new blasting initiators. Another object is to provide new compositions especially suitable as ignition charges in blasting caps. Still another object is to provide ignitable leadtellurium-fatty acid salt compositions containingan additive comprising one or more selected materials to regulate their fuse ignitability characteristics when employed as initiators in a delay cap. Other aspects and objects will be apparent from the accompanying disclosure and the appended claims.

In accordance with this invention lead-tellurium compositions containing lead and tellurium in ignitable pro ate.

2,867,518 Patented Jan. 6, 1959 r .2. portions, together with a minor amount of a metal salt of a long chain fatty acid, are provided as blasting initiators. Further in accordance with this invention leadtellurium compositions are provided which contain lead and tellurium in ignitable proportions, together with a minor proportion of a metal salt of a long chain fatty acid, and at least one additive capable of altering the fuse ignitability characteristics of the said composition when utilized as an initiator in a blasting cap and selected from the group of magnesium, aluminum, silicon, phosphorus and sulfur. Still in accordance with this invention a method is provided for regulating firing time said mixture to decrease the said firing time to a predetermined value.

Although it is within the scope of my invention to utilize any ignitable proportions of lead and tellurium in my compositions, the preferred composition will contain from about to 81 weight percent lead and from about 19 to 65 weight percent tellurium. The amount of long chain fatty acid salt, as discussed more fully hereinafter, will generally be within the range of about 0.1 to 6 weight percent. The amount of additive component utilized dependslupon the problem at hand, being, how ever, in the order of from about 0.3 up to 4.5 weight percent or higher if desired. Substantially stoichiometric proportions of lead and tellurium are employed in my compositions to achieve maximum heat of reaction, which is of particular importance in the use of the composition as an ignition mixture in a delay cap in order to assure ignition of the fuse. However, other than stoichiometric proportions can be employed for that purpose when desired, particularly when an additive material is present to increase the fuse ignitability by increasing the heat of the burning reaction as described hereinafter.

The following tabulation of data are illustrative of firing time obtained with lead-tellurium-fatty acid salt compositions of this invention as detonator compositions in short-period delay caps, there being no separate delay charge present. Also included are firing time data obtained with lead-tellurium-fatty acid salts containing silicon. Firing time data, illustrative of lead-tellurium mixtures alone, are included for comparison. The data illustrate the regulatory effect of the fatty acid salt components of this invention on the burning rate of leadtellurium mixtures. The base charge and primer compositions employed were pentaerythritol tetranitrate and diazodinitrophenol, respectively, in conventional proportions. The lead-tellurium proportions were 6l.9/38.l -in all cases. All tests were made in a standard 25 caliber shell.

Table I Weight Summary of firing time of ignl- Num- (milliseconds) Ignition mixture tion or her of delay tests charge, Avg. Range Spread grams Pb-T o. 7 10 163 65485 130 Ph-Te/Pb steal/Si, 97.5/l .5/l.0 0.7 10 44 85- 55 20 Pb-Te/Pb stea 99/1 0.7 10 45 40- 10 Pb-Te/Pb stea., 98.5/15 0. 7 10 45 40- 15 Pb-Te/Pb stea., 98/2 0. 7 10 50 40- 75 35 Pb-Te 1. 4 10 440 200-620 420 Pb-Te/Pb stew/Si. 97.5,'1.5/l.0. 1. 4 10 60- 85 20 Pb-Te/Pb stea 99 1 1. 4 8 67 60- 15 1 Lead stearate.

The following tabulation of data are illustrative of firing 'timesobtained with lead-'tellurium-fattyacid metal admixed by any suitable procedure. Generally the particle size of the resulting composition will be in the range of about 1 to 70 microns, although a particle size outside that range can be utilized if desired. The composition is loaded into any desired form of blasting cap in any usual manner. No air space is required in the cap since Stoichlometric proportions (61.9-38.1). "Stolchiometric proportions (72.4-27.6). "Pressed (0.7 gram) on primer charge. Pressed (0.65 gram) onprimer charge.

The foregoing examples demonstrate that metal fatty 'acid saltcomponents of the compositions of this invention provide for improved firing accuracy as manifest by the lowered spread in firing times of lead-tellurium mixtures that is achieved, and formarked reduction in firing time of lead-tellurium ignition mixtures to. provide for regulation of -those firing times tosignificantly reduced values. The additive components, namely magnesium, silicon, aluminum, sulfur'and phosphorus impart increased heat of reaction to provide supplemental heat for igniting difficultly ignitable delay fuses in blasting caps.

While any metal salt of the long chain fatty acids can be employed in the practice of my invention,'the stearates,

'oleates, laurates, caprates, caprylates, and palmitates are advantageously employed. Further illustrative of the fatty acid salt components of this invention are: lead stearate, cadmium stearate, iron stearate, magnesium stearate, aluminum stearate, zinc stearate, calcium stearate, leadlaurate, cadmium laurate, iron laurate, magnesium laurate,

aluminum laurate, zinc laurate, calcium 'laurate', lead palmitate, cadmium palmitate, iron palmitate, magnesium palmitate, aluminum palmitate, zinc palmitate, calcium palmitate, lead caprylate, lead caprate, cadmium caprylate, cadmium caprate, iron caprylate, iron caprate, mag

nesium caprylate, aluminum caprylate, zinc caprylate,

calcium caprylate, magnesium caprate,-aluminum caprate, zinc caprate and calcium caprate. Lead stearate is the preferred fatty acid salt component of the compositions of this invention.

The amount of fatty acid salt in my compositions is sufficient to impart improved accuracy of burning lead-tel- "lurium'mixtures. Lead-tellurium mixtures as blasting, in-

T able ll I Num- Fuse Firing time ('ms.) Ignition mix. (loose) Fuse powder ber of length, tests inches Avg Range Spread .'Pb-'-' e 1 BaOz Te(70-3 g/Ph Sn, 50/50 0.192 470 420-1, 000 580 B802 'Ie(7030 lPbSn, /50.--- -770 700-1, 950 1, 250 -Pb -Te [Pb estate/Si, 0.5/1.0 BaO; Te(7030)/PbSu, 50/50 210- '195- '250 :Bb-TeJ/Pbjsteurnte/Sl, 9 .5/1.5/1.0 BaOrIe(7030\/PbSn, 50/50. 395 360- 420 Pb*'1e IPb stearate/Si, 97.5/1.5/l.0 BaOz-Te(-30)/PbSn, 50/50. 670 640- 690 50 .Pb-Te -e--, s t Pb'-Se /B a0z Se(82-18); 70/30 a 3 68 280- 600; 220 "Pb -Te [Pb stearate/Si,,97.5/1.5/1.0. Pb-Se /BaOzSe (82-18); 70/30 g 90 25 -Pb-Te lF'b stearat'e/Si, 97.5/1'.5/1.0 BaO?/Se(7B25) -10 395 '60 Pb-Te lPb stearate/Mg, 97.5/1.5/1.0 Ba0z/Se(7525) 10 20 the composition develops practicallyno gas on burning.

As illustrative, thecomposition may be loaded loosely into any form of ventless delay cap assembly above the fuse and the usualsulfurplug holding the usual bridge- W ire placed above the loosely loaded composition with the bridgewire embedded in the composition. Similarly, a composition may be loosely loaded into any ordinary blasting cap above the priming charge.

As will be evident to those skilled in the art, various modifications can be made or followed, in the light of the foregoing, disclosure and discussion, without departing from the spirit or scope ofthe disclosure or from the scope of the claims.

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

'1. As a blasting initiator composition, an ignition mixture of lead and tellurium containing a metal salt of a above. that which will undesirably-desensitize the composition to ignition, the above maximum value depending v will notrupture the cap casing or dislodge thebridgewire jiupon firing. Inpreparing a composition of this invention in accordance with one. embodimennthe ingredients are reduced to a finely divided form and are then intimately long chain fatty acid an amount. sufficient to decrease the burning time of said lead and'tellurium but less than that which completely desensitizes the'said composition to ignition, whereby spreadin burning time of said'lead and tellurium is also decreased.

'2. A composition of claim 1 containing a sufiicient amount of at least one additive selected'from the group consisting of aluminum, magnesium,-silicon, sulfur and phosphorus to impart increased heat of reaction from burning of said composition.

3. As a new composition a finely. divided blasting initiator mixture consisting essentially of from' 35 to 81 weight percent lead, from 19'to 6.5 'weight percenttellurim'n and from 0.1 to 6 weightpercent-of a metal salt ofa long chain fatty acid.

4. A composition of claim'3 wherein said lead and tellurium are present in substantially a lead/tellurium weight ratio of 6l.9:38.1.

5. A new composition consisting essentially of a finely divided blasting initiator mixture of from 35 to 81 weight percent lead, from 19 to 65 weight percent tellurium, from 0.1 to 6 weight percent of a metal salt of a long chain fatty acid, and from 0.3 to 4.5 weight percent of at least one additive of the group of aluminum, magnesium, silicon, sulfur and phosphorus.

6.. A composition of claim 5 wherein said additive is silicon.

7.'A' composition of claim 5 wherein said additive is magnesium.

8.'A composition of claim 5 wherein said additive aluminum.

9. A.composition of claim 5 wherein said additive 10. A composition of claim 5 wherein said additive is phosphorus.

11. In an electric blasting cap containing a detonatable base charge and a primer charge for initiating said base charge upon being heated, and an ignition charge for generation of heat, from burning of same, to cause initiation of said primer, the improvement providing, as said ignition charge, an ignition mixture of lead and tellurium containing a metal salt of a long chain fatty acid in an amount sufiicient to decrease the burning time of said lead and tellurium but less than that which completely desensitizes the said composition to ignition.

12. A cap of claim 11 wherein said charge contains at least one of magnesium, aluminum, silicon, sulfur and phosphorus as an additive in an amount suificient to impart increased heat of reaction from burning of said igni tion charge.

13. A composition of claim 1 wherein said metal salt is a stearate.

14. A composition of claim 3 wherein said fatty acid is of the group of stearic, oleic, lauric, capric, caprylic and palmitic.

15. As a new blasting initiator composition a finely divided mixture consisting essentially of from 35 to 81 weight percent lead, 19 to 65 weight percent tellurium, and from 0.2 to 2 weight percent of a metal salt of a long chain fatty acid.

16. A composition of claim 15 wherein said salt is lead stearate.

17. A blasting cap of claim 11 wherein the said ignition charge is the sole ignitable charge for initiating said primer.

18. A blasting cap of claim 17 wherein said charge contains at least one of magnesium, aluminum, silicon, sulfur and phosphorus as an additive in an amount sufficient to impart increased heat of reaction from burning of said ignition charge.

19. As a new blasting initiator composition, a finely divided mixture consisting essentially of from to 81 Weight percent lead, from 19 to weight percent tellurium, from 0.2 to 2 weight percent lead stearate, and from 0.3 to 4.5 percent silicon.

20. As a new blasting initiator composition, a finely divided mixture consisting essentially of from 35 to 81 weight percent lead, from 19 to 65 weight percent tellurium, from 0.2 to 2 weight percent lead stearate, and from 0.3 to 4.5 percent magnesium.

References Cited in the file of this patent UNITED STATES PATENTS Re. 19,661 Nash July 30, 1935 2,146,033 Seavey et al. Feb. 7, 1939 2,370,159 Hanley Feb. 27, 1945

Claims (1)

1. AS A BLASTING INITIATOR COMPOSITION, AN IGNITION MIXTURE OF LEAD AND TELLURIUM CONTAINING A METAL SALT OF A LONG CHAIN FATTY ACID IN AN AMOUNT SUFFICIENT TO DECREASE THE BURNING TIME OF SAID LEAD AND TELLURIUM BUT LESS THAN THAT WHICH COMPLETELY DESENSITIZES THE SAID COMPOSITION TO IGNITION, WHEREBY SPREAD IN BURNING TIME OF SAID LEAD AND TELLURIUM IS ALSO DECREASED.