CA1308914C - Foamable explosive combinations - Google Patents
Foamable explosive combinationsInfo
- Publication number
- CA1308914C CA1308914C CA000508553A CA508553A CA1308914C CA 1308914 C CA1308914 C CA 1308914C CA 000508553 A CA000508553 A CA 000508553A CA 508553 A CA508553 A CA 508553A CA 1308914 C CA1308914 C CA 1308914C
- Authority
- CA
- Canada
- Prior art keywords
- combination
- liquid
- boiling point
- low boiling
- explosive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B47/00—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase
- C06B47/14—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase comprising a solid component and an aqueous phase
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
- F42D1/08—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
- F42D1/10—Feeding explosives in granular or slurry form; Feeding explosives by pneumatic or hydraulic pressure
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Containers And Packaging Bodies Having A Special Means To Remove Contents (AREA)
Abstract
Abstract The invention relates to a foamable explosive combination comprising a so called "liquid" explosive, conveniently an oxidizing salt or salt-saturated aqueous composition, with a low boiling point liquid dispersed through the combination. The low boiling point liquid is selected to maintain its liquid form at normal temperature and elevated pressure and to vaporize at atmospheric temperature and pressure. When packaged in a container part of the low boiling point liquid, or a second low boiling point liquid, vaporizes to maintain at least part of the first low boiling point liquid in liquid form within the combination and in such a state the combination is stable and has a relatively long shelf life. When the combination is released from the container to atmosphere the low boiling point liquid in the combination vaporizes to foam the combination.
The combination may also include metals, such as aluminum, or solids explosive materials in finely divided form.
The combination may also include metals, such as aluminum, or solids explosive materials in finely divided form.
Description
This invention relates to foamable, explosives containing compositions.
Liquid explosive combinations as colloids, suspensions or solutions are well known in the art and the advantages of small bubbles in such liquid combinations are also well known. Thus, in U.S. Patent Specification No. 3582411 it is suggested that the 5 inclusion of a large number of small bubbles in a liquid explosive combination affords active reaction centers which assists propagation of the detonation reaction whilst in U.S. Patent No. 35865S3 the compositions disclosed, being liquid explosive combinations with gas bubbles therein, are described as being highly brisant with high detonation velocity and capable of being produced in a wide range of densities.
A difflculty with many prior art aerated or so called "foamed" explosive combinations resides in obtaining a uniform distribution of small bubbles throughout the liquid combination and many foamed explosives have a very short shelf-life. A
further difflculty with many prior art foamed explosive combinations is that they are sensitive and poor travellers. These difficulties have led to the need for foaming the 15 liquid combinations as close to the site of use as is possible.
U.S. Patent Specification No. 3582411 discloses a method for making a foamed liquid explosives combination by the steps of adding a foam promoting and viscosity increasing agent, such as a salt water foamer, to a liquid solution, such as an explosive slurry, blending at least part of the liquid solution with a gas to produce 20 fine bubbles therein, and thereafter mixing the gas-containing liquid with particulate fuel solids which impart sensitivity to the composition. It should be noted that in this disclosure the bubbles are not formed within the liquid composition but are introduced by mechanical means, for example by the apparatus described in the publication. Such mechanical introduction of gas into the liquid combination, as is well known, does not 25 introduce bubbles of uniform siæ in the density required throughout the liquid combination, the foamed product has a poor shelf life and the disclosure requires the addition of fuel solids after the foaming of the liquid, again by a mechanical means, which can lose gas from the foamed liquid, and, as stated, the addition of the fuel F~ 'J~
Liquid explosive combinations as colloids, suspensions or solutions are well known in the art and the advantages of small bubbles in such liquid combinations are also well known. Thus, in U.S. Patent Specification No. 3582411 it is suggested that the 5 inclusion of a large number of small bubbles in a liquid explosive combination affords active reaction centers which assists propagation of the detonation reaction whilst in U.S. Patent No. 35865S3 the compositions disclosed, being liquid explosive combinations with gas bubbles therein, are described as being highly brisant with high detonation velocity and capable of being produced in a wide range of densities.
A difflculty with many prior art aerated or so called "foamed" explosive combinations resides in obtaining a uniform distribution of small bubbles throughout the liquid combination and many foamed explosives have a very short shelf-life. A
further difflculty with many prior art foamed explosive combinations is that they are sensitive and poor travellers. These difficulties have led to the need for foaming the 15 liquid combinations as close to the site of use as is possible.
U.S. Patent Specification No. 3582411 discloses a method for making a foamed liquid explosives combination by the steps of adding a foam promoting and viscosity increasing agent, such as a salt water foamer, to a liquid solution, such as an explosive slurry, blending at least part of the liquid solution with a gas to produce 20 fine bubbles therein, and thereafter mixing the gas-containing liquid with particulate fuel solids which impart sensitivity to the composition. It should be noted that in this disclosure the bubbles are not formed within the liquid composition but are introduced by mechanical means, for example by the apparatus described in the publication. Such mechanical introduction of gas into the liquid combination, as is well known, does not 25 introduce bubbles of uniform siæ in the density required throughout the liquid combination, the foamed product has a poor shelf life and the disclosure requires the addition of fuel solids after the foaming of the liquid, again by a mechanical means, which can lose gas from the foamed liquid, and, as stated, the addition of the fuel F~ 'J~
solids renders the combination sensitive. Further, the apparatus illustrated is not suited for location at many sites of use, such as remote quarry sites.
U.S. Patent Specification No. 3586553 proposes the use of proteinaceous material in a liquid explosives combination and suggests that such material functions as an effective foaming agent but the specification emphasises mechanical mixing to introduce gas to the liquid explosives combination and there is no suggestion in this publication that the proteinaceous material can, without agitation of the liquidexplosives combination, produce gas bubbles within said combination.
U.S. Patent Specification No. 3713919 discloses semi-solid colloidal dispersions of water-bearing blasting agents including N.N.dinitrosopentamethylene-tetramine which, it is suggested, is mixed with the explosive mixture at temperatures between 130F to 180F, whereupon said additive decomposes to form gas bubbles within the explosive mixture. It should be noted that the size of the bubbles generated and the distribution of said bubbles through the explosive mixture must be entirely dependant upon the degree of mixing, mechanical mixing, the mixing operation is carried out at elevated temperatures and the foamed explosive mixture must be transported, in foamed condition, to the required location of use.
It is an object of the present invention to obviate or mitigate the above mentioned disadvantages. Accordingly, the invention provides a foamable explosive combination comprising a liquid or semi-liquid explosive composition with a low boiling point liquid dispersed through said composition, said low boiling point liquid being selected to maintain its liquid form at normal temperature and elevated pressures and to vaporize at normal temperature and pressure whereby to form gas bubbles distributed through the said composition.
The explosive combination proposed by the present invention has the advantages that:
1. it can be held in a very stable condition for long periods and thereby can have a long, safe, storage life, simply by maintaining the combination under pressure to hold the low boiling point liquid in liquid form;
13~3 2. said combination can be foamed when required and at the location of use so that the problems of transporting a foamed sensitive explosive combination are avoided;
3. the use of a liquid to generate the bubbles avoids the need to 5 mechanically agitate the composition to beat bubbles into the combination;
U.S. Patent Specification No. 3586553 proposes the use of proteinaceous material in a liquid explosives combination and suggests that such material functions as an effective foaming agent but the specification emphasises mechanical mixing to introduce gas to the liquid explosives combination and there is no suggestion in this publication that the proteinaceous material can, without agitation of the liquidexplosives combination, produce gas bubbles within said combination.
U.S. Patent Specification No. 3713919 discloses semi-solid colloidal dispersions of water-bearing blasting agents including N.N.dinitrosopentamethylene-tetramine which, it is suggested, is mixed with the explosive mixture at temperatures between 130F to 180F, whereupon said additive decomposes to form gas bubbles within the explosive mixture. It should be noted that the size of the bubbles generated and the distribution of said bubbles through the explosive mixture must be entirely dependant upon the degree of mixing, mechanical mixing, the mixing operation is carried out at elevated temperatures and the foamed explosive mixture must be transported, in foamed condition, to the required location of use.
It is an object of the present invention to obviate or mitigate the above mentioned disadvantages. Accordingly, the invention provides a foamable explosive combination comprising a liquid or semi-liquid explosive composition with a low boiling point liquid dispersed through said composition, said low boiling point liquid being selected to maintain its liquid form at normal temperature and elevated pressures and to vaporize at normal temperature and pressure whereby to form gas bubbles distributed through the said composition.
The explosive combination proposed by the present invention has the advantages that:
1. it can be held in a very stable condition for long periods and thereby can have a long, safe, storage life, simply by maintaining the combination under pressure to hold the low boiling point liquid in liquid form;
13~3 2. said combination can be foamed when required and at the location of use so that the problems of transporting a foamed sensitive explosive combination are avoided;
3. the use of a liquid to generate the bubbles avoids the need to 5 mechanically agitate the composition to beat bubbles into the combination;
4. the use of a liquid, dispersed through the explosive composition, to generate the bubbles allows a more uniform distribution of bubbles than can be obtained with prior art combinations;
5. the use of a low boiling point liquid to generate the bubbles ;n the 10 composition by vapourization allows the explosive combination to be returned to a safe, unfoamed, condition simply by pressurizing the foam to reduce the vapouriæd liquid to liquid form, an important advantage not possible with prior art combinations which rely on decomposition of an ingredient to generate the gas bubbles.
Preferably said explosive composition comprises the liquid phase of a 15 solution or colloid and the said low boiling point liquid is at least partially contained within the discontinuous phase of the system.
Preferably the said explosive composition comprises an oxidizing salt-saturated aqueous solution.
Conveniently the combination may include additional explosive material 20 or materials, in divided form, dispersed through the said explosive composition.
The combination proposed by the invention may conveniently include any of the liquid, or semi-liquid, explosives compositions known in the art but preferably comprises a solution or colloid wherein the liquid phase is an oxidizing salt or salts-saturated aqueous solution. The discontinuous phase then conveniently includes a25 surfactant and the low boiling point liquid whereupon, when exposed to normaltemperature and pressure, the low boiling point liquid forms gas bubbles dispersed through the discontinuous phase, and thereby through the said continuous phase.
In one embodiment proposed by the invention the foamable explosive combination is packaged in a container and part of the low boiling point liquid is allowed to vapouriæ to pressurize the container contents, thereby to maintain the other part of said liquid in liquid form.
In another embodiment proposed by the invention the foamable explosive combination is packaged in a container and all the low boiling point liquid in the 5 combination is maintained in liquid form by pressurizing the combination with a propellant gas which can maintain the container under pressure during storage conditions and assist in expelling the explosive combination from the container when required.
The surfactants involved may be nonionic, cationic or amphoteric in 10 nature or combinations thereof. It (or they) should be capable of producing a suitable stable oil/water emulsion or dispersion of the selected low boiling point liquid in the liquid explosive composition. Suitable emulsifiers are amine oxides in combination with alkanolamides exemplified by stearic monoethanol-amide or tallow mono (di) ethanolamide. Further emulsifiers which may be used with selected low boiling point 15 liquids are alkyl ethers, alkyl esters and other common types of surfactants.To achieve a satisfactory foam stability the preferred surfactants will be required to have limited solubility in the oxidiser phase in order that, on ejection from the container followed by vapourization of the low boiling point liquid, crystallization or precipitation occurs due to the loss in solvency and/or cooling effect. N.B. In the 20 concentrate the surfactant may be present as a colloidal or other fine dispersion or dissolved foam at normal temperatures.
In this composition the surface active agent and other organic additives (see below) may also function as fuel for the explosive combination.
In addition to the surface active materials described above, other non-25 surface active materials, or low HLB surfactants of low stability may be dispersed oremulsified into the system to further increase foam stability. Such materials, precipitating/crystallizing or vapourization of the low boiling point liquid add further strength to the bubble wall. Such materials are exemplified by lauryl, myristyl, catyl, stearyl and behenyl alcohols, dobanols and similar synthetic mixtures. Other ~3~
additives, potentially useful in this role, would be other wax-like materials such as natural waxes, synthetic waxes, hydrocarbon waxes, stearyl stearate, myristyl stearate, glycerol esters, mono, di and triesters of pentaerythritol, trimethylol propane, sorbitol or other polyol (some of which will also be surface active) of sufficient molecular S weight to render it crystalline.
Polymers compatible with the system will also function as foam stabilizers.
The preferred oxidizing salt in the combination is ammonium nitrate.
However, other salts such as X Y Z are equally applicable used alone or in 10 combination with ammonium nitrate.
The oxidizer is preferably included in the combination in the form of a saturated aqueous solution containing between X and Y% mt/mt oxidiær salt.
The low boiling point liquid is preferably of the so called aerosol type.
Virtually any aerosol propellant compatible with the selected surfactant may be used.
15 Preferably said liquids involve CC12F or CCIF2CCIF2 or combinations thereof or other halogenated hydrocarbons capable of producing an internal pressure of X - Y
butane, isobutane, propane, pentone, heptane and other low boiling point hydrocarbons are also suitable, depending upon their compatibility with the selected surfactant(s).
Foam stability is affected by the type of low boiling point liquid selected 20 for the composition and the properties of the low boiling point liquid in the combination will determine the density of the combination when foamed.
When the foamable combination is pressurized in a container by a second low boiling point liquid said liquid may be selected from the above defined low boiling point liquids but preferably said second low boiling point liquid is selected to25 vapourize at lower temperature than the low boiling point liquid in the combination to maintain said liquid in liquid form in the combination.
When the combination is released to normal temperature and pressure (atmospheric temperature and pressure at the location of use) the low boiling point liquid dispersed through the combination vapouriæs very rapidly to foam the combination.
It is probable that a stable foam results from the bubbles of low boiling point liquid being surrounded by a liquid saturated solution of oxidizer salt containing S solid particles of surfactant and/or other matter as described previously, coalescence of the bubbles being prevented or retarded by the solid particles within the bubble wall. Foams of extreme stability will result if the oxidiær or oxidizing salt is thrown out of solution by extreme cooling due to rapid vapourization of the low boiling point liquid. Hence the foam is formed by vaporization of the dispersed low boiling point liquid within the oxidizing salt phase, the stability of the foam resulting from the formation of a solid or solid/liquid wall of aqueous oxidizer salt and particulate surfactant and/or additive and/or oxidizer salt enabling bubble formation to occur.
When the composition is packaged in a container having means for controllably releasing the combination the said combination may be released directly at the location of use with no preparation other than a minor manual shaking to ensure dispersal of the low boiling point liquid through the combination.
The container may be fully charged with the combination and the low boiling point liquid to maintain the container under pressure and to propel the combination from the container at the location or site of use.
When so processed the container preferably has a capacity of at least 20 ml.
In an alternative arrangement the composition, without the low boiling point liquid or the liquid for pressurizing the container, may be packaged remote from the location of use and the said liquids added at the location of use.
The means for controllably releasing the composition from a container may conveniently comprise a manually operable valve mounted on the container or a nozzle connected to the container by rigid or flexible duct means. Thus the container may discharge foamable explosive composition in similar manner to a spray can, or via a wand or boom.
-ih 13~
In one preferred embodiment a cylindrical container with an aerosol type valve has a discharge tube to the valve extending into the container. A flexible bag containing the foamable explosive composition has its mouth secured to said discharge tube so that only the bag contents can be discharged from the valve. A low boiling S point liquid, selected to vaporiæ at a lower temperature than the low boiling point liquid in the combination in the bag, is charged into the container externally of the bag.
With this arrangement the low boiling point liquid externally of the bag is at least partially vaporiæd at all times to maintain the bag under pressure whereby to maintain the low boiling point liquid in the composition in liquid form. When the valve is manually activated explosive composition in the bag is propelled up thedischarge tube and through the valve to atmosphere by the pressure of the vaporiæd liquid surrounding the bag. On release to atmosphere the low boiling point liquid dispersed through the explosive combination vaporiæs to form small bubbles within the explosive combination, thus "foaming" said released combination. This type of construction allows the combination to be completely discharged from the container under pressure without any loss of low boiling point liquid from the combination.
The following Examples, in which all percentages are weight, are given by way of illustration.
An explosive aqueous solution (having all components dissolved at the ambient temperature 20C) was prepared containing:
47% monmethylamine nitrate 13% water 30% ammonium nitrate, and 10% sodium perchlorate As emulsifier there was added from 9 to 10% (based on the total weight of the composition) of an emulsifier consisting of:
55% Fenopon~ CD 128 (Ammonium salt of ethyloxylated coconut fatty acid sulphate) 22~ stearic mono-ethanolamide 11% propylene glycol, and 11% cetostearyl alcohol This emulsifier was warmed until melted and mixed in the aqueous solution with gentle agitation.
EXAMPLE l 100 g of the composition described above was charged into a conventional aerosol type container with Sg of Arcton~ 114 (I.C.I.), a commercially available aerosol propellant. When the container was discharged, under pressure generated by vaporization of the Arcton 114, the discharge combination foamed, clearly illustrating that part of the Arcton 114 had been absorbed into the combination and vaporiæd on discharge.
100 g of the composition described above was charged into a conventional aerosol type container with 5g of CC12 F2 (Propellant 12). When thecontainer was discharged the discharging combination foamed, again clearly illustrating that part of the propellant had been absorbed in liquid form into the combination and vaporized within the combination on exposure to atmosphere.
It will be appreciated that in both the above examples the low boiling point liquid serving to foam the combination served the dual purpose of expelling the composition from the container and whilst both the above embodiments fulfilled all the requirements of the invention there is difficulty with such dual purpose low boiling point liquids in controlling the volume of gas within the foam whilst maintaining a uniform pressure for the discharge.
* Trademark 13~
g 100 g of the composition described above was charged into a flexible bag with lg of CCIF2 CCIF2 (Propellant 114) and the mouth of the bag was secured to the discharge tube of a conventional aerosol type valve in an aerosol container. A volume 5 of 5g of propellant 114 was charged into the container to surround the bag.
On discharge of this arrangement it was found that virtually all the propellant 114 within the bag formed small gas bubbles distributed through the discharge composition and the propellant surrounding the bag discharged the bag contents at substantially uniform pressure. As the propellant within the bag, 10 constituting the low boiling point liquid within the explosive combination, was all expelled within the explosive combination it will be readily seen that the proportion of the low boiling point liquid in the explosive combination can be varied to give desired foam densities to the foamed combinations, and combinations with the gasphase between 10% and 90% of the volume of the foamed combination can be readily15 and easily obtained.
As is known, finely divided metal powder such as aluminum powder, or finely divided self explosive material such as PETN may be suspended in the combination to further increase its explosive power.
Preferably said explosive composition comprises the liquid phase of a 15 solution or colloid and the said low boiling point liquid is at least partially contained within the discontinuous phase of the system.
Preferably the said explosive composition comprises an oxidizing salt-saturated aqueous solution.
Conveniently the combination may include additional explosive material 20 or materials, in divided form, dispersed through the said explosive composition.
The combination proposed by the invention may conveniently include any of the liquid, or semi-liquid, explosives compositions known in the art but preferably comprises a solution or colloid wherein the liquid phase is an oxidizing salt or salts-saturated aqueous solution. The discontinuous phase then conveniently includes a25 surfactant and the low boiling point liquid whereupon, when exposed to normaltemperature and pressure, the low boiling point liquid forms gas bubbles dispersed through the discontinuous phase, and thereby through the said continuous phase.
In one embodiment proposed by the invention the foamable explosive combination is packaged in a container and part of the low boiling point liquid is allowed to vapouriæ to pressurize the container contents, thereby to maintain the other part of said liquid in liquid form.
In another embodiment proposed by the invention the foamable explosive combination is packaged in a container and all the low boiling point liquid in the 5 combination is maintained in liquid form by pressurizing the combination with a propellant gas which can maintain the container under pressure during storage conditions and assist in expelling the explosive combination from the container when required.
The surfactants involved may be nonionic, cationic or amphoteric in 10 nature or combinations thereof. It (or they) should be capable of producing a suitable stable oil/water emulsion or dispersion of the selected low boiling point liquid in the liquid explosive composition. Suitable emulsifiers are amine oxides in combination with alkanolamides exemplified by stearic monoethanol-amide or tallow mono (di) ethanolamide. Further emulsifiers which may be used with selected low boiling point 15 liquids are alkyl ethers, alkyl esters and other common types of surfactants.To achieve a satisfactory foam stability the preferred surfactants will be required to have limited solubility in the oxidiser phase in order that, on ejection from the container followed by vapourization of the low boiling point liquid, crystallization or precipitation occurs due to the loss in solvency and/or cooling effect. N.B. In the 20 concentrate the surfactant may be present as a colloidal or other fine dispersion or dissolved foam at normal temperatures.
In this composition the surface active agent and other organic additives (see below) may also function as fuel for the explosive combination.
In addition to the surface active materials described above, other non-25 surface active materials, or low HLB surfactants of low stability may be dispersed oremulsified into the system to further increase foam stability. Such materials, precipitating/crystallizing or vapourization of the low boiling point liquid add further strength to the bubble wall. Such materials are exemplified by lauryl, myristyl, catyl, stearyl and behenyl alcohols, dobanols and similar synthetic mixtures. Other ~3~
additives, potentially useful in this role, would be other wax-like materials such as natural waxes, synthetic waxes, hydrocarbon waxes, stearyl stearate, myristyl stearate, glycerol esters, mono, di and triesters of pentaerythritol, trimethylol propane, sorbitol or other polyol (some of which will also be surface active) of sufficient molecular S weight to render it crystalline.
Polymers compatible with the system will also function as foam stabilizers.
The preferred oxidizing salt in the combination is ammonium nitrate.
However, other salts such as X Y Z are equally applicable used alone or in 10 combination with ammonium nitrate.
The oxidizer is preferably included in the combination in the form of a saturated aqueous solution containing between X and Y% mt/mt oxidiær salt.
The low boiling point liquid is preferably of the so called aerosol type.
Virtually any aerosol propellant compatible with the selected surfactant may be used.
15 Preferably said liquids involve CC12F or CCIF2CCIF2 or combinations thereof or other halogenated hydrocarbons capable of producing an internal pressure of X - Y
butane, isobutane, propane, pentone, heptane and other low boiling point hydrocarbons are also suitable, depending upon their compatibility with the selected surfactant(s).
Foam stability is affected by the type of low boiling point liquid selected 20 for the composition and the properties of the low boiling point liquid in the combination will determine the density of the combination when foamed.
When the foamable combination is pressurized in a container by a second low boiling point liquid said liquid may be selected from the above defined low boiling point liquids but preferably said second low boiling point liquid is selected to25 vapourize at lower temperature than the low boiling point liquid in the combination to maintain said liquid in liquid form in the combination.
When the combination is released to normal temperature and pressure (atmospheric temperature and pressure at the location of use) the low boiling point liquid dispersed through the combination vapouriæs very rapidly to foam the combination.
It is probable that a stable foam results from the bubbles of low boiling point liquid being surrounded by a liquid saturated solution of oxidizer salt containing S solid particles of surfactant and/or other matter as described previously, coalescence of the bubbles being prevented or retarded by the solid particles within the bubble wall. Foams of extreme stability will result if the oxidiær or oxidizing salt is thrown out of solution by extreme cooling due to rapid vapourization of the low boiling point liquid. Hence the foam is formed by vaporization of the dispersed low boiling point liquid within the oxidizing salt phase, the stability of the foam resulting from the formation of a solid or solid/liquid wall of aqueous oxidizer salt and particulate surfactant and/or additive and/or oxidizer salt enabling bubble formation to occur.
When the composition is packaged in a container having means for controllably releasing the combination the said combination may be released directly at the location of use with no preparation other than a minor manual shaking to ensure dispersal of the low boiling point liquid through the combination.
The container may be fully charged with the combination and the low boiling point liquid to maintain the container under pressure and to propel the combination from the container at the location or site of use.
When so processed the container preferably has a capacity of at least 20 ml.
In an alternative arrangement the composition, without the low boiling point liquid or the liquid for pressurizing the container, may be packaged remote from the location of use and the said liquids added at the location of use.
The means for controllably releasing the composition from a container may conveniently comprise a manually operable valve mounted on the container or a nozzle connected to the container by rigid or flexible duct means. Thus the container may discharge foamable explosive composition in similar manner to a spray can, or via a wand or boom.
-ih 13~
In one preferred embodiment a cylindrical container with an aerosol type valve has a discharge tube to the valve extending into the container. A flexible bag containing the foamable explosive composition has its mouth secured to said discharge tube so that only the bag contents can be discharged from the valve. A low boiling S point liquid, selected to vaporiæ at a lower temperature than the low boiling point liquid in the combination in the bag, is charged into the container externally of the bag.
With this arrangement the low boiling point liquid externally of the bag is at least partially vaporiæd at all times to maintain the bag under pressure whereby to maintain the low boiling point liquid in the composition in liquid form. When the valve is manually activated explosive composition in the bag is propelled up thedischarge tube and through the valve to atmosphere by the pressure of the vaporiæd liquid surrounding the bag. On release to atmosphere the low boiling point liquid dispersed through the explosive combination vaporiæs to form small bubbles within the explosive combination, thus "foaming" said released combination. This type of construction allows the combination to be completely discharged from the container under pressure without any loss of low boiling point liquid from the combination.
The following Examples, in which all percentages are weight, are given by way of illustration.
An explosive aqueous solution (having all components dissolved at the ambient temperature 20C) was prepared containing:
47% monmethylamine nitrate 13% water 30% ammonium nitrate, and 10% sodium perchlorate As emulsifier there was added from 9 to 10% (based on the total weight of the composition) of an emulsifier consisting of:
55% Fenopon~ CD 128 (Ammonium salt of ethyloxylated coconut fatty acid sulphate) 22~ stearic mono-ethanolamide 11% propylene glycol, and 11% cetostearyl alcohol This emulsifier was warmed until melted and mixed in the aqueous solution with gentle agitation.
EXAMPLE l 100 g of the composition described above was charged into a conventional aerosol type container with Sg of Arcton~ 114 (I.C.I.), a commercially available aerosol propellant. When the container was discharged, under pressure generated by vaporization of the Arcton 114, the discharge combination foamed, clearly illustrating that part of the Arcton 114 had been absorbed into the combination and vaporiæd on discharge.
100 g of the composition described above was charged into a conventional aerosol type container with 5g of CC12 F2 (Propellant 12). When thecontainer was discharged the discharging combination foamed, again clearly illustrating that part of the propellant had been absorbed in liquid form into the combination and vaporized within the combination on exposure to atmosphere.
It will be appreciated that in both the above examples the low boiling point liquid serving to foam the combination served the dual purpose of expelling the composition from the container and whilst both the above embodiments fulfilled all the requirements of the invention there is difficulty with such dual purpose low boiling point liquids in controlling the volume of gas within the foam whilst maintaining a uniform pressure for the discharge.
* Trademark 13~
g 100 g of the composition described above was charged into a flexible bag with lg of CCIF2 CCIF2 (Propellant 114) and the mouth of the bag was secured to the discharge tube of a conventional aerosol type valve in an aerosol container. A volume 5 of 5g of propellant 114 was charged into the container to surround the bag.
On discharge of this arrangement it was found that virtually all the propellant 114 within the bag formed small gas bubbles distributed through the discharge composition and the propellant surrounding the bag discharged the bag contents at substantially uniform pressure. As the propellant within the bag, 10 constituting the low boiling point liquid within the explosive combination, was all expelled within the explosive combination it will be readily seen that the proportion of the low boiling point liquid in the explosive combination can be varied to give desired foam densities to the foamed combinations, and combinations with the gasphase between 10% and 90% of the volume of the foamed combination can be readily15 and easily obtained.
As is known, finely divided metal powder such as aluminum powder, or finely divided self explosive material such as PETN may be suspended in the combination to further increase its explosive power.
Claims (12)
1. A foamable explosive combination comprising a liquid, or semi- liquid, explosive composition with a low boiling point liquid dispersed through said composition, said low boiling point liquid being selected to maintain its liquid form at atmospheric temperature and elevated pressures and to vaporize at atmospheric temperature and pressure, whereby to form gas bubbles distributed through the said composition.
2. A foamable explosive combination according to claim 1 and wherein said explosive composition comprises a continuous liquid phase of a solution or colloid and the said low boiling point liquid is at least partially contained within a discontinuous phase of the system.
3. A foamable explosive combination according to claim 1 or claim 2 and wherein said explosive composition comprises an oxidizing salt or salts-saturated, aqueous solution.
4. A foamable explosive combination according to claim 1 and wherein the combination includes additional explosive material or materials, in divided form, dispersed through the said explosive composition.
5. A foamable explosive combination comprising an explosive composition dispersed in a liquid medium, a low boiling point liquid selected to maintain its liquid form at atmospheric temperature and elevated pressure and to vaporize at atmospheric temperature and pressure, and an emulsifying agent selected to at least aid dispersion of the said low boiling point liquid through the liquid medium.
6. A foamable explosive combination according to claim 5 and wherein the emulsifying agent is a surfactant selected to form a solution with at least part of the said low boiling point liquid.
7. A foamable explosive combination according to claim 5 and wherein the explosive composition comprises an oxidizing salt or salts, the liquid medium is water, and the proportion of salt or salts to water is at least sufficient to form a salts-saturated solution.
8. A foamable explosive combination according to claim 1 packaged in a container having means for controllably releasing the combination, said container being pressurized by vaporization of a low boiling point liquid within the container whereby said pressurization of the container by vaporization of the low boiling point liquid series to maintain the low boiling point liquid in the combination in liquid form and further serves to propel the said combination from the container when required.
9. A packaged, foamable explosive combination according to claim 8 and wherein said low boiling point liquid serving to pressurize the container and to propel said combination from said container is the same low boiling point liquid as that within the combination.
10. A packaged, foamable explosive combination according to claim 8 and wherein said low boiling point liquid serving to pressurize the said container and to propel said combination from the said container is a different liquid from that said low boiling point liquid in the combination.
11. A packaged, foamable, explosive combination according to claim 10 and wherein said low boiling point liquid serving to pressurize the container and to propel said combination from the container is isolated from the combination by a flexible membrane within the said container.
12. A foamable explosive combination according to claim 1 or claim 5 and wherein the proportion of the low boiling point liquid within the combination is selected so that on release to atmospheric temperature and pressure the vaporized, low boiling point liquid in the released combination adjusts the density of the combination to the desired density.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08516606A GB2160857B (en) | 1984-06-29 | 1985-07-01 | Explosive compositions |
| CA000508553A CA1308914C (en) | 1984-06-29 | 1986-05-06 | Foamable explosive combinations |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8416594 | 1984-06-29 | ||
| CA000508553A CA1308914C (en) | 1984-06-29 | 1986-05-06 | Foamable explosive combinations |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1308914C true CA1308914C (en) | 1992-10-20 |
Family
ID=25670990
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000508553A Expired - Lifetime CA1308914C (en) | 1984-06-29 | 1986-05-06 | Foamable explosive combinations |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1308914C (en) |
| GB (1) | GB2160857B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001002318A1 (en) * | 1999-06-30 | 2001-01-11 | Orica Explosives Technology Pty Ltd | Manufacture of emulsion explosives |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1303858C (en) * | 1988-08-10 | 1992-06-23 | Her Majesty The Queen In Right Of Canada As Represented By The Minister Of National Defence Of Her Majesty's Canadian Government | Foamed nitroparaffin explosive composition |
| CA2040346C (en) * | 1991-04-12 | 2001-06-12 | Fortunato Villamagna | Explosive comprising a foamed sensitizer |
| US5456729A (en) * | 1992-04-09 | 1995-10-10 | Ici Canada Inc. | Sensitizer and use |
-
1985
- 1985-07-01 GB GB08516606A patent/GB2160857B/en not_active Expired
-
1986
- 1986-05-06 CA CA000508553A patent/CA1308914C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001002318A1 (en) * | 1999-06-30 | 2001-01-11 | Orica Explosives Technology Pty Ltd | Manufacture of emulsion explosives |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8516606D0 (en) | 1985-08-07 |
| GB2160857A (en) | 1986-01-02 |
| GB2160857B (en) | 1988-02-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |