Method for gassing explosives especially at low temperatures

Abstract

The invention provides a method for gassing an explosive to sensitise the explosive and/or modify the density of the explosive. The method comprises reacting at least one oxidiser with at least one nitrogen containing compound in the explosive to generate nitrogen gas. The explosive is formulated to effect diffusion of the oxidiser and/or the compound into contact with each other, the nitrogen gas being generated by oxidation of the compound by the oxidiser. The invention extends to the explosive compositions themselves.

1 . A method for gassing an explosive to sensitise the explosive and/or modify the density of the explosive, comprising reacting at least one oxidiser with at least one nitrogen containing compound in the explosive to generate nitrogen gas, the explosive being formulated to drive formation of a respective neutrally charged form of the oxidiser and/or the compound to effect diffusion of the oxidiser and/or the compound into contact with each other, and the nitrogen gas being generated by oxidation of the compound by the oxidiser. 
     
     
         2 . A method according to  claim 1  wherein the oxidiser and the nitrogen compound are separated from each other by fuel lamellae in the explosive and the neutrally charged form of the oxidiser and/or the compound diffuse across the fuel lamellae into contact with one another. 
     
     
         3 . A method according to  claim 1  wherein the explosive is formulated to effect diffusion of the oxidiser into contact with the nitrogen compound. 
     
     
         4 . A method according to  claim 3  wherein the explosive is formulated for protonation of the oxidiser or the release of at least one proton from the oxidiser, to effect the diffusion of the oxidiser. 
     
     
         5 . A method according to  claim 4  wherein the explosive comprises a proton donor for protonating the oxidiser. 
     
     
         6 . A method according to  claim 4  wherein the explosive comprises a proton acceptor for maintaining pH above a predetermined lower limit to inhibit crystallisation in the explosive. 
     
     
         7 . A method according to  claim 3  wherein the explosive comprises a pH regulating agent which acts as the proton donor and a proton acceptor for maintaining the pH above a predetermined lower limit. 
     
     
         8 . A method according to  claim 1  wherein the explosive is formulated to have a pH for obtaining the diffusion of the oxidiser. 
     
     
         9 . A method according to  claim 8  wherein the explosive comprises a pH regulating agent which is essentially non-diffusing across fuel lamellae, for maintaining the pH at a level to control the rate of diffusion of the oxidiser. 
     
     
         10 . A method according to  claim 1  wherein the explosive comprises a proton transfer agent for transferring at least one proton across fuel lamellae or from one phase to another of the explosive, to promote the diffusion of the oxidiser and/or the nitrogen compound. 
     
     
         11 . A method according to  claim 10  wherein the proton transfer agent is provided by a pH regulating agent. 
     
     
         12 . A method according to  claim 10  wherein pH is regulated to delay the diffusion of the oxidiser and thereby the gassing of the explosive. 
     
     
         13 . A method according to  claim 9  wherein the pH regulating agent comprises one or more compounds selected from the group consisting of partially or completely deprotonated forms of inorganic acids and carboxylic acids, and salts thereof. 
     
     
         14 . A method according to  claim 13  wherein the pH regulating agent comprises one or more of phosphoric acid, acetic acid, formic acid, citric acid, tartaric acid, furoic acid, fumaric acid, salicylic acid, malonic acid, phthalic acid, sulfanilic acid, mandelic acid, malic acid, butyric acid, oxalic acid, and salts thereof. 
     
     
         15 . A method according to  claim 10  wherein the proton transfer agent comprises one or more compounds selected from the group consisting of inorganic acids, organic acids, carboxylic acids, and salts thereof, the explosive being formulated such that at least some of these compounds exist in the explosive in a neutral form. 
     
     
         16 . A method according to  claim 15  wherein the proton transfer agent comprises one or more compounds selected from the group consisting of alkyl carboxylic acids, acetic acid, formic acid, phosphoric acid, citric acid, tartaric acid, furoic acid, fumaric acid, salicylic acid, malonic acid, phthalic acid, sulfanilic acid, mandelic acid, malic acid, butyric acid, oxalic acid, and salts thereof. 
     
     
         17 . A method according to  claim 1  wherein the at least one nitrogen compound is selected from the group consisting of NH 3 /NH 4   + , ammonium salts, urea, amines, hydrazines, hydrazides, azides, triazoles, tetrazoles, and derivatives of urea, amines, hydrazines, hydrazides, azides, triazoles, tetrazoles, and nitrogen compounds having 3 or more nitrogen atoms for generation of the nitrogen gas. 
     
     
         18 . A method according to  claim 1  wherein the nitrogen compound is selected from the group consisting of NH 3 /NH 4   + , hydrazides, and derivatives of hydrazides. 
     
     
         19 . A method according to  claim 1  wherein the explosive comprises NH 3 /NH 4   +  and at least one other said nitrogen compound, the gassing of the explosive including oxidation of the NH 3 /NH 4   + . 
     
     
         20 . A method according to  claim 19  wherein the other said nitrogen compound is selected from the group consisting of urea, amines, azides, hydrazines, hydrazides, tetrazoles, triazoles, and derivatives thereof. 
     
     
         21 . A method according to  claim 1  wherein the oxidiser is selected from the group consisting of hypohalites and hypohalous acids. 
     
     
         22 . A method according to  claim 1  wherein the temperature at which the reaction occurs is 40° C. or less. 
     
     
         23 . A method according to  claim 22  wherein the temperature is 25° C. or less. 
     
     
         24 . A method according  claim 1  in which the oxidiser is added to the explosive subsequent to incorporation of the nitrogen compound in the explosive. 
     
     
         25 . A method for gassing an explosive to sensitise the explosive and/or modify the density of the explosive, comprising reacting at least one oxidiser with at least one nitrogen containing compound in the explosive to generate nitrogen gas, the oxidiser and the compound initially being in different phases of the explosive to one another, and the explosive being formulated to drive formation of a respective neutrally charged form of the oxidiser and/or the compound to effect diffusion of the oxidiser and/or compound into contact with each other whereby nitrogen gas is generated via oxidation of the nitrogen compound by the oxidiser. 
     
     
         26 . An explosive gassed by a method as defined in  claim 1 . 
     
     
         27 . An explosive comprising at least one oxidiser and at least one nitrogen containing compound, the explosive being formulated to drive formation of a respective neutrally charged form of the oxidiser and/or the compound to effect diffusion of the oxidiser and/or the compound into contact with each other for oxidation of the compound by the oxidiser to produce nitrogen gas from the compound for gassing of the explosive. 
     
     
         28 . An explosive according to  claim 27  formulated to effect diffusion of the oxidiser into contact with the nitrogen compound. 
     
     
         29 . An explosive comprising at least one oxidiser and at least one nitrogen containing compound, the oxidiser and the compound being in different phases of the explosive to one another, and the explosive being formulated to drive formation of a respective neutrally charged form of the oxidiser and/or the compound to effect diffusion of the oxidiser and/or the compound into contact with each other for oxidation of the compound by the oxidiser to produce nitrogen gas from the compound for gassing of the explosive.