United States Patent (19) 11 4,270,435 Hurst 45) Jun. 2, 1981

54 DESENSITIZED PRIMARY EXPLOSIVES OTHER PUBLICATIONS Urbanski, Chemistry and Technology of Explosives, (75) Inventor: Gerald L. Hurst, Austin, Tex. vol. 3, Pergamon Press, New York, 1976, pp. 157 to 160. Primary Examiner-Leland A. Sebastian 73 Assignee: Atlas Powder Company, Dallas, Tex. Attorney, Agent, or Firm-Richards, Harris & Medlock 21) Appl. No.: 39,351 57 ABSTRACT A method for manufacturing explosive articles which contain primary explosives and therefore present explo 22 Filed: May 16, 1979 sion hazards during conventional loading and packag ing operations is disclosed which includes desensitizing 51 Int. Cl...... C06B 37/00; F42B 3/10 the primary explosive such as silver fulminate, for ex (52) U.S. C...... 86/1 R; 86/20 R; ample, by admixing therewith an effective amount of a 149/33; 423/42; 423/365 desensitizing agent to form a resulting composition so as (58) Field of Search ...... 86/1 R, 20 R; 149/33; to render the primary explosive insensitive to shock, 423/42, 365 depositing the desensitized primary explosive on a sub strate material, and thereafter, resensitizing the primary explosive by allowing decomposition of the resulting 56 References Cited composition to thereby recapture the sensitivity of the U.S. PATENT DOCUMENTS primary explosive so deposited. 56,167 7/1866 Boldt ...... 149/33

2,067,213 1/1937 Snelling a so seases a so 149/33 X 20 Claims, No Drawings 4,270,435 1. 2 ing it with a desensitizing agent selected from the group DESENSITIZED PRIMARY EXPLOSIVES consisting of ammonia and certain amines in aqueous solution. The resulting silver fulminate compound is BACKGROUND OF THE INVENTION substantially insensitive to detonation by shock and may In one aspect this invention relates to a method for be processed by various methods in this insensitive reversibly desensitizing primary explosives so as to condition without a high risk of impact detonation. render them substantially incapable of detonation by Thus, a bulk quantity of silver fulminate can be depos shock or impact. Another aspect of this invention re ited on various substrate materials and otherwise han lates to a method for manufacturing explosive articles dled or packaged with relative safety. The resulting which contain primary explosives wherein the dangers 10 compound is unstable and will decompose, releasing, normally attending the production of such articles due when ammonia is used as the desensitizing agent, gase to shock sensitivity are substantially alleviated. In still a ous ammonia and leaving resensitized silver fulminate further aspect, the present invention relates to a method after a period of time under normal conditions. How for packaging the explosive materials comprising pri ever, in order to insure that the silver fulminate will mary explosives which provides for desensitization of 15 regain its sensitivity a small amount of resensitizing the primary explosive in bulk quantities with the subse agent in the form of an acid which will readily react quent recapture of shock sensitivity when smaller dis with liberated gas and drive the equilibrium of the reac crete portions of the primary explosive have been pack tion in a manner favoring the release of ammonia from aged. the silver fulminate is desirable. Thus, the discrete, de The term "primary explosive' as used herein refers to 20 sensitized portions of silver fulminate can be resensit shock sensitive explosive compositions conventionally ized once the dangers attending accidental impact deto used as initial detonating agents for less sensitive explo nation of a bulk quantity of silver fulminate are no sive compositions. These primary explosives are more longer present. easily detonated by application of impact or friction than are non-impact sensitive explosives such as ammo 25 DETAILED DESCRIPTION OF THE nium nitrate, TNT and cellulose nitrate, for example. INVENTION Specifically, the method of the present invention is directed to the primary explosives such as silver fulmi I have discovered that by employing certain types of nate (AgONC). Silver fulminate has been used in the desensitizing agents in a liquid orgaseous phase or com past in the manufacture of fireworks and similar materi 30 bination thereof, silver fulminate can be made substan als such as impact torpedo noisemakers. However, be tially insensitive to detonation by shock or impact. As cause of its high impact sensitivity, handling bulk quan used in this description, for purposes of the invention tities of silver fulminate has presented substantial explo any reference to silver fulminate is to be taken as being sion hazards in the past. One example of an application applicable to other primary explosives that exhibit de of silver fulminate is the pyrotechnic noisemaker set 35 sensitizing characteristics similar to those of silver full forth in U.S. Pat. No. 4,005,657 issued Feb. 1, 1977. The minate. Thus, bulk quantities of silver fulminate which noisemaking device disclosed therein comprises a small have heretofore presented explosion hazards when han amount of impact sensitive explosive particles produced dled on a commercial scale during loading and packag from coating gravel or sand with silver fulminate em ing operations, for example, can be desensitized accord ploying a suitable adhesive such as a water soluble ca ing to the method of the present invention to alleviate sein glue. While relatively small amounts of the explo those hazards and then resensitized in a manner which sive silver fulminate are present in each of the individual recaptures the desirable impact sensitivity and explosive noisemaker devices, manufacturing such noisemakers characteristics of this primary explosive. on a commercial scale presents the problem of handling The desensitization can be accomplished by admixing bulk quantities of silver fulminate. Thus, for example, if 45 silver fulminate with an aqueous solution of ammonia, it is desired to produce explosive particles on a commer certain amines or mixtures thereof to thereby form a cial scale comprising a silver fulminate admixture of resulting compound which is insensitive to shock or sand, the handling of bulk quantities of silver fulminate impact detonation. The desensitization of silver fulmi will involve a fairly high degree of risk of accidental nate can be accomplished by contacting the explosive impact detonation of the explosive. Furthermore, while 50 with desensitizing agents either in liquid or vapor form silver fulminate has the explosive properties necessary and can be accomplished by conventional methods of for use in commercial blasting caps and military muni mixing, agitation, and tumbling action. Normally, tions, the impact sensitivity of the material presents contact time in a range of from about one minute to safety hazards which in most cases outweigh the desir about one hour will be sufficient to insure desensitiza ability of employing this explosive in those types of 55 tion of the silver fulminate. Preferably, the desensitiza operations. tion of the silver fulminate is incorporated in the manu Thus, a method by which silver fulminate could be facturing of silver fulminate from raw materials. For desensitized while in a bulk quantity so as not to be example, silver fulminate can be made by reacting ap subject to accidental impact detonation and then later proximately stoichiometric quantities of nitric acid, resensitized to thereby recapture its excellent impact ethyl alcohol and silver, preferably with a slight excess sensitivity and explosive properties once it has been of nitric acid and ethyl alcohol being present. The re packaged in smaller discrete quantities is desirable and sulting reaction forms silver fulminate which is a white would facilitate the use of silver fulminate in a wide flocculent at about 80°C. Thereafter, most of the super variety of explosive applications. natant is removed and the white flocculent is water 65 washed by multiple decantation. The desensitizing SUMMARY OF THE INVENTION agent is gradually introduced into the wash water in I have discovered that an explosive metal fulminate amounts of less than about 1% by weight of desensitiz such as silver fulminate can be desensitized by contact ing agent up to about 30% by weight of desensitizing 4,270,435 3 4. agent. The desensitized product is formed during the can be added in relatively small amounts to the explo multiple decantation of the white flocculent. sive article containing the desensitized silver fulminate Although it is not necessary to understand the mecha to thereby reactivate it shortly before shipping. nism by which the silver fulminate is desensitized, it is According to the invention, the preferred desensitiz theorized that a coordination compound is formed be- 5 ing agent is ammonia. Ammonia may be used in either a tween the silver fulminate and the desensitizing agent, gaseous or liquid form with an inert diluent. As previ such as silver fulminate diammoniate when ammonia is ously described, preferably the ammonia is in an aque used as the desensitizing agent, for example. The result ous solution or in the gas phase when contacted with ing coordination compound is substantially insensitive the silver fulminate. Other desensitizing agents that can to detonation by shock or impact although it is unstable 10 be used in accordance with the invention include cer and will gradually decompose causing the silver fulmi tain amine compounds such as pyridine or aniline. Other nate to regain its shock sensitivity. This desensitization amines which are known to work include piperazine process allows for safer handling of bulk quantities of (diethylenediamine), n-ethyl piperazine and triethylam silver fulminate. ine. Any amine compound which will desensitize the Because of silver fulminate's brisance in its normally 15 silver fulminate by producing an unstable compound sensitive state, usually only small quantities thereof will which liberates a gaseous product leaving behind the be employed in explosive devices such as capwells for silver fulminate in an impact sensitive state can be used munitions, blasting caps for the explosive industry, fire in accordance with the method of the present invention. works, noisemakers and the like. A desensitized quan Similarly, the amines are present in the gas phase or in tity of silver fulminate can be deposited onto a substrate 20 an aqueous solution when contacting the silver fulmi such as the interior of a capwell for munitions, the cylin nate or in any other inert liquid or gaseous diluent. drical tube of conventional blasting caps, while other One use of the method of the present invention com substrate materials include, for example, granular earth prises the manufacture of toy noisemakers using silver materials such as sand or silica. Optionally, a suitable fulminate. Thus, according to the steps outlined above, adhesive can be used to insure that the deposited silver 25 a bulk quantity of silver fulminate can be manufactured fulminate explosive remains intact on the desired sub and washed with an aqueous ammonia solution, for strate surface. For example, in addition to being loaded example, as previously described and in sufficient quan into conventional types of explosive cartridges and the tities to effect the desensitization of the silver fulminate. like by packaging equipment, the desensitized silver The deactivated silver fulminate can then be tumbled fulminate can be admixed with inorganic particulate 30 with, for example, fine grain sand in sufficient quantities matter such as sand or silica and bonded thereto using a to substantially coat the sand. It is preferred, although suitable amount of an adhesive such as a water-soluble not necessary, that the tumbling occurs in an ammonia casein glue amount. Preferably, and as will be hereinaf vapor atmosphere. The sand and silver fulminate are ter described, no adhesive is used to coat particles with tumbled until a uniform homogeneous mix is formed silver fulminate, since the adhesive tends to lower the 35 which appears dry, although some water will be pres amount of energy which can be released by the silver ent. fulminate. When coating sand with silver fulminate, the pre Once the ammonia desensitized silver fulminate is ferred weight ratio of silver fulminate to sand is be deposited on a suitable substrate or within the explosive tween about 1:400 and 1:200. The preferred particle size article being manufactured, the desensitized silver full- 40 for sand or any other type of particle that will be used, minate can be reactivated to its initial level of sensitivity for example, in toy noisemakers, is from about 16 to 18 to impact detonation after placing the article in an en mesh. Other materials could be used and no specific closed container with an effective amount of a Lewis shape or configuration of the particles is required. For acid which will accelerate the rate at which ammonia is example, any inert material which would not desensitize removed from the ammonia desensitized silver fulmi- 45 the silver fulminate could be used and the configuration nate . of the particles could be, for example, spherical. As The resensitization process can be effected in a num mentioned previously, it is preferred that no adhesive be ber of ways including bringing such a resensitizing used so that the full explosive force of the silver fulmi agent into contact with the desensitized silver fulminate nate can be utilized, for example, in toy noisemakers, for once it has been packaged in discrete portions. As previ- 50 maximum noise output. ously described, the desensitized silver fulminate is an To make a noisemaker, for example, the silver fulmi unstable compound and will slowly decompose leaving nate coated sand can then be wrapped in tissue paper or silver fulminate in a shock sensitive state. For example, otherwise packaged with each discrete package con the desensitized silver fulminate will regain its shock taining from about 0.0005 to about 0.001 grams of silver and impact sensitivity when maintained at ambient tem- 55 fulminate on about 0.2 grams of sand and boxed in quan perature after a period of from about 2 hours to about 3 tities of about 50 to a box containing about 5 grams of days. This time can be reduced by mildly heating the sawdust, for example. Before the noisemakers are uti desensitized silver fulminate. By effecting the resensiti lized, the silver fulminate must be resensitized so that it zation after the bulk quantity of silver fulminate has is shock or impact sensitive. Since the desensitized com been packaged or otherwise separated into discrete 60 pound is unstable, decomposition into shock sensitive smaller portions, the risk of large catastrophic acciden silver fulminate will result. The resensitization process tal explosions can be avoided. Thus, the step of recap can be accelerated by mildly heating the desensitized turing the sensitivity of the silver fulminate can be ac silver fulminate or by maintaining a resensitizing agent, complished by placing the explosive articles containing such as a Lewis acid, in the presence of the desensitized the desensitized silver fulminate in an acid environment, 65 silver fulminate. For example, just before the package such as, for example, an enclosed chamber wherein a containing the quantity of noisemakers is sealed, two or Lewis acid is present in a solid, liquid or gaseous state. three drops of phosphoric acid or some other Lewis In another embodiment, acids such as phosphoric acid acid is added to the sawdust and then the package is 4,270,435 5 6 sealed. The presence of a Lewis acid will insure essen group consisting of aliphatic amines, aromatic tially complete and rapid desensitization of the coordi nation compound as any ammonia liberated by the de amines and ammonia; composition of the coordination compound will react (b) depositing said desensitized silver fulminate on a with the acid to form, when phosphoric acid is used for 5 substrate material; example, ammonium dihydrogen phosphate. By the (c) packaging discrete portions of said substrate de time the package is opened and the products are sold posited bulk quantities of desensitized silver fulmi commercially, the acid will have reacted with the liber nate; ated ammonia to drive the equilibrium of the reaction in (d) resensitizing said packaged discrete portions of which decomposition of the coordination compound 10 silver fulminate by contacting said silver fulminate occurs in the direction of decomposition (formation of with an effective amount of a resensitizing agent. ammonia and silver fulminate) to completely free the 6. The method as recited in claim 5 wherein said silver fulminate of the ammonia as follows, thereby resensitizing agent is a Lewis acid. reactivating the silver fulminate: 7. A method of desensitizing and resensitizing silver 15 fulminate comprising contacting said silver fulminate to Silver fulminate diammoniate-Silver form a resulting composition with a desensitizing com fulminate -- Ammonia (1) position comprising a mixture of at least one compound Ammonia--Phosphoric Acid-Ammonium selected from the group consisting of ammonia and dihydrogen phosphate. (2) amine compounds and an inert diluent therefor in a 20 concentration and amount sufficient to eliminate the Thus, the package contained in the noisemakers in ef impact sensitivity of said silver fulminate but which fect becomes reactivated as it sits on the shelf. It is to be resulting composition decomposes to liberate in gaseous understood that silver fulminate used for other applica form at least part of said desensitizing composition to tions and desensitized in accordance with the invention resensitize said silver fulminate. can be similarly resensitized as previously described 25 8. The method as recited in claim 7 wherein the de herein. composition of said resulting composition is accelerated This invention has been described with respect to the by causing a Lewis acid to react with the gas liberated preferred embodiments thereof. However, modifica by said resulting composition. tions and adaptations will now be apparent to one 9. The method as recited in claim 7 wherein the de skilled in the art upon reading the subject specification. 30 composition of said resulting composition is accelerated All such modifications and adaptations which fall by mildly heating said resulting composition. within the scope of the appended claims are intended to 10. The method as recited in claim 7 wherein the inert be covered thereby. diluent is water. I claim: 11. The method as recited in claim 6 wherein the 1. A method of desensitizing and resensitizing explo-35 concentration of compounds selected from the group sive metal fulminate primary explosives comprising: consisting of ammonia and amine compounds are pres (a) contacting the explosive metal fulminate with an ent in an amount of from about 0.5% to 100% by weight effective amount of desensitizing agent selected of the total desensitizing composition. from the group consisting of aliphatic amines, aro 12. The method as recited in claim 7, 10 or 11 wherein matic amines and ammonia to desensitize the explo- 40 said desensitizing agent is present in gaseous form. sive metal fulminate; and (b) subsequently contacting the explosive metal full 13. The method as recited in claim 7 or 11 wherein minate with a Lewis acid in an amount effective to said desensitizing agent is present in liquid form. thereby recapture the impact sensitivity of the ex 14. The method as recited in claim 7, 10 or 11 wherein plosive metal fulminate. 45 said desensitizing agent is present in both liquid and 2. The method as recited in claim 1 wherein the ex gaseous phases. plosive metal fulminate is silver fulminate and said 15. A method of manufacturing silver fulminate com method is used for manufacturing explosive articles prising: containing silver fulminate as a primary explosive. (a) reacting approximately stoichiometric quantities 3. The method as recited in claim 2 further compris- 50 of nitric acid, ethyl alcohol and silver to form a ing depositing said desensitized primary explosive on silver fulminate flocculent; substrate material. (b) separating the majority of the supernatent from 4. In a method of manufacturing explosive articles the silver fulminate flocculent; containing primary explosives the improvement com (c) washing the flocculent silver fulminate with water prising: 55 to remove the remainder of the supernatent; depositing silver fulminate on a substrate surface in a (d) desensitizing the silver fulminate after water desensitized condition, said desensitized condition washing by contacting the silver fulminate with a being effected by first admixing said silver fulmi desensitizing composition comprising a mixture of nate with an effective amount of a desensitizing at least one compound selected from the group agent selected from the group consisting of ali- 60 consisting of ammonia and amine compounds and phatic amines, aromatic amines, and ammonia. an inert diluent therefor in a concentration and 5. A method for packaging silver fulminate contain amount sufficient to form a resulting compound ing explosive articles wherein the danger of shock deto which has low impact sensitivity relative to the nation of a bulk quantity of said silver fulminate is sub impact sensitivity of silver fulminate but which stantially eliminated, comprising: 65 resulting composition decomposes to liberate in (a) desensitizing a bulk quantity of silver fulminate by gaseous form at least part of said desensitizing com contacting said silver fulminate with an effective position to provide impact sensitive silver fulmi amount of a desensitizing agent selected from the nate. 4,270,435 7 8 16. The method as recited in claim 15 wherein said having an ammonia concentration of about 1% by desensitizing composition includes from about 0.5% to weight and ending with an aqeuous composition having about 100% ammonia by weight of said total desensitiz an ammonia concentration of about 30% by weight. ing composition. 20. The method as recited in claim 15 further com 17. The method as recited in claim 15 or 16 wherein said desensitizing agent is present in gaseous form. prising: 18. The method as recited in claim 15 or 16 wherein depositing said desensitized silver fulminate upon a said desensitizing agent is present in liquid form. substrate; and 19. The method as recited in claim 16 wherein said subsequently resensitizing said silver fulminate by silver fulminate is contacted, after water washing, with 10 maintaining said desensitized silver fulminate in the desensitizing compositions of increasing concentrations presence of a Lewis acid. of ammonia, beginning with an aqueous composition

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