CA2162411A1 - Emulsifying agent for use in explosive compositions - Google Patents
Emulsifying agent for use in explosive compositionsInfo
- Publication number
- CA2162411A1 CA2162411A1 CA002162411A CA2162411A CA2162411A1 CA 2162411 A1 CA2162411 A1 CA 2162411A1 CA 002162411 A CA002162411 A CA 002162411A CA 2162411 A CA2162411 A CA 2162411A CA 2162411 A1 CA2162411 A1 CA 2162411A1
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- Prior art keywords
- emulsifying agent
- emulsion
- chain
- lipophilic
- agent according
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- 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
- C06B47/145—Water in oil emulsion type explosives in which a carbonaceous fuel forms the continuous phase
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F21/00—Dissolving
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D207/00—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom
- C07D207/02—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D207/30—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having two double bonds between ring members or between ring members and non-ring members
- C07D207/34—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having two double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D207/36—Oxygen or sulfur atoms
- C07D207/40—2,5-Pyrrolidine-diones
- C07D207/404—2,5-Pyrrolidine-diones with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to other ring carbon atoms, e.g. succinimide
- C07D207/408—Radicals containing only hydrogen and carbon atoms attached to ring carbon atoms
- C07D207/412—Acyclic radicals containing more than six carbon atoms
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
- C09K23/017—Mixtures of compounds
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
- C09K23/16—Amines or polyamines
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/02—Well-drilling compositions
- C09K8/32—Non-aqueous well-drilling compositions, e.g. oil-based
- C09K8/36—Water-in-oil emulsions
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
- Liquid Carbonaceous Fuels (AREA)
Abstract
An emulsion explosive emulsifying agent comprising a first lipophilic group, a second lipophilic group and a hydrophilic group, all of which are connected to a linking group, wherein said second lipophilic group has more than one olefinic unsaturation in its hydrocarbon chain.
Preferred compounds of the present invention have the structure shown in Formula IA:
Formula IA
wherein L1 is a first lipophilic chain, L~ is a second, unsaturated lipophilic chain having an olefinic unsaturated level greater than 1, R is hydrogen or a hydrophilic group, and n is ~ 1, and m ~ 0.
The emulsifying agent allows emulsion explosives having improved stability to be produced.
Preferred compounds of the present invention have the structure shown in Formula IA:
Formula IA
wherein L1 is a first lipophilic chain, L~ is a second, unsaturated lipophilic chain having an olefinic unsaturated level greater than 1, R is hydrogen or a hydrophilic group, and n is ~ 1, and m ~ 0.
The emulsifying agent allows emulsion explosives having improved stability to be produced.
Description
ICICAN 816 2162~11 EmulsifYing Aqent for Use in Explosive Compositions Field of the Invention This invention relates to an emulsifying agent suitable for use in water-in-fuel and melt-in-fuel explosives.
Description of the Related Art Water-in-fuel and melt-in-fuel emulsion explosives are well known in the explosives industry and are routinely used in civilian excavation, mining and quarrying. Water-in-fuel emulsions comprise a discontinuous phase of droplets of an oxygen supplying component such as an aqueous oxidiser salt solution dispersed in a continuous phase of oils and/or waxes in the presence of one or more emulsifying agents. The oxygen-supplying discontinuous phase of a melt-in-fuel emulsion comprises only a small proportion of water or adventitious water only. The discontinuous phase may be a eutectic composition, that is the melting point of the composition is either at the eutectic or in the region of the eutectic of the component salts of the discontinuous phase. Where used herein the term emulsion refers to both water-in-fuel and melt-in-fuel emulsions.
In general the emulsions suitable for use in emulsion explosives are relatively inert until mixed with sensitizing agents such as self-detonable compounds (e.g.
nitroglycerine) or void material such as glass microballoons, gas bubbles or the like.
Water-in-fuel emulsion explosives compositions were first disclosed by Bluhm in United States Patent 3,447,978 and comprise (a) a discontinuous aqueous phase comprising -21~2~11 discrete droplets of an aqueous solution of inorganic oxygen-releasing salts; (b) a continuous water-immiscible organic phase throughout which the droplets are dispersed and (c) an emulsifier which forms an emulsion of the S droplets of oxidizer salt solution throughout the continuous organic phase. They may also include sensitizing agents such as a discontinuous gaseous phase.
Subsequently, numerous documents have been published which provide modifications and/or improvements over the formulations originally described by Bluhm.
A key component in the formulation of an emulsion explosive composition is the selection of the proper emulsifying agent. The type of emulsifying agent chosen will have an effect on many properties of the emulsion including, for example, the ease of formation of the emulsion, the discontinuous phase droplet size and the tendency of the droplets to crystallise or coalesce. These properties are particularly relevant to the storage stability of the emulsion and ultimately, the performance of the composition as an explosive.
Australian patent application no. 40006/85 (Cooper &
Baker) discloses emulsion explosive compositions in which the emulsifier is a reaction product of a poly[alk(en)yl]
species (e.g. an alkylated succinic anhydride) and amines such as ethylene diamine, diethylene triamine and mono- and di-ethanolamines.
McKenzie in US patent No. 4,931,110 describes the use of a bis(alkanolamine or polyol) amide and/or ester derivatives of, for example, polyalk(en)yl succinic anhydride compounds as suitable emulsifying agents.
Polyalk(en)yl succinic anhydride compounds are described by Baker in Canadian patent No. 1,244,463.
Forsberg et al. in US patent No. 4,840,687 describe an emulsion explosive composition wherein the emulsifier is a nitrogen-containing emulsifier derived from at least one carboxylic acylating agent, a polyamine and an acidic compound.
-Additionally, Chattopadhyay, in Canadian patent application No. 2,076,987 describes the use of a mixed emulsifying agent system for emulsion explosives comprising a surfactant and co-surfactant, each having branched chain hydrocarbon tails.
However, the identification of additional emulsifying agents is still desirable in order to lead to improved emulsifying agent or emulsion properties.
Emulsifying agents perform several functions during the formation and subsequent stabilisation of an emulsion explosive composition. As an emulsion is being formed the emulsifying agent must be able to lower the interfacial tension between the discontinuous and continuous phases and thus stabilize the interfaces between the oxidiser salt droplets and the fuel. The emulsifying agent must also form a structured bilayer at the interface to aid suppression of droplet coalescence and inhibit the crystallisation of salts in the droplets. It is also important that the emulsifying agent be able to preserve bilayer integrity dynamically when an emulsion explosive is subjected to shear stress, such as the shear stress which occurs during pumping.
Providing a single emulsifying agent which satisfies all these criteria is not straightforward. Accordingly, an emulsifier system is often employed which contains a mixture of emulsifying agents; each of which satisfies different criteria. A particularly preferred mixed emulsifier system of the prior art is described in the aforementioned Cooper & Baker and Chattopadhyay references and by Yates et al. in US patent No. 4,710,248 which describes the use of a derivatized polyisobutene succinic anhydride surfactant in combination with a co-surfactant such as sorbitan monooleate. The emulsifying agents of the prior art are relatively effective in performing some functions but improvements are still sought.
For example, it has proved particularly difficult to identify suitable emulsifying agents for certain types of emulsions for use in emulsion explosives compositions. In particular, emulsifying agents of the prior art have proved inadequate for the formation of emulsions which can be formed into stable, oxygen balanced emulsion explosives compositions. In the field of emulsion explosives, a S composition is said to be oxygen balanced at the point at which adequate oxygen from the components is made available for the explosive detonation to go to completion, leaving no unreacted material. Oxygen balanced compositions are particularly desirable because they provide maximum energy and minimum fume.
Many emulsion explosive compositions currently in use are oxygen negative, that is there is insufficient oxidizer salt present to achieve total reaction of all materials. In these oxygen negative formulations, the ratio of oxidiser phase to fuel oil phase is commonly between 90:10 and 94:6 and the detonation of these materials tends to produce toxic NOX fumes. Ideally, maximum energy release and minimum fume would be provided by an oxygen balanced composition. Typically, these oxygen balanced compositions have an oxidiser phase:fuel oil phase ratio of between about 95:5 and 96:4. However oxygen balanced compositions can be difficult to prepare, in practice, because of the lack of suitable emulsifying agents which can stabilize such low fuel phase-content compositions.
It is thus an object of the present invention to provide an improved emulsifying agent capable of providing the desired properties described hereinabove.
Summary of the Invention It has now been found that a particular class of emulsifier is particularly suitable for use in emulsion explosive compositions, and in particular, for use in oxygen balanced emulsion explosive compositions.
Accordingly, the present invention provides an emulsifying agent suitable for use in an emulsion explosive composition comprising a hydrophilic species, a first lipophilic chain ICICAN 816 ~ 4 ~ ~
-which is attached to said hydrophilic species by a first linking moiety, and a second lipophilic chain which is attached to said hydrophilic species by a second linking moiety, and wherein said second lipophilic chain has more than one olefinic unsaturated bond in its hydrocarbon chain.
As is known by those skilled in the art, the degree of olefinic unsaturation for the second lipophilic chain may be an average value for the individual lipophilic molecules. Accordingly, the level of unsaturation of the second lipophilic chain may approach the value of 1, but preferably, the second lipophilic chain comprises at least two olefinic unsaturated bonds in its hydrocarbon chain, and preferably these two unsaturated bonds are separated by at least one saturated carbon bond (e.g. -CH2-).
Further, the current invention also provides an emulsion suitable for use in an emulsion explosive composition having a continuous hydrocarbon phase, a discontinuous aqueous salt or eutectic phase, and at least one emulsifying agent, wherein said emulsifying agent is an emulsifying agent as described hereinabove with respect to the present invention.
Description of the Preferred Embodiments In a particularly preferred embodiment the emulsifying agent is as described hereinabove with respect to the current invention, and has the structure shown for formula I;
L1 \ /Rx M1 ~ N Formula I
\(CHz)m - M2 L2 wherein L1 is a first lipophilic chain, L2 is a second, unsaturated lipophilic chain having an olefinic unsaturated level greater 21~2411 than 1, R is hydrogen or a hydrophilic group, or a direct bond to M1 when x is 0, M1 is an ester, amide or imide linkage, M2 is an ester linkage, and m is 2 O, and x is O or 1.
The first lipophilic chain (L1) may be either monomeric or polymeric in nature. The chain structure should incorporate a backbone sequence of at least 10 and preferably not more than 500 linked atoms. These linked atoms may be entirely carbon atoms or they may be predominantly carbon atoms interrupted by hetero atoms such as oxygen or nitrogen. A preferred type of first lipophilic chain is a saturated or unsaturated hydrocarbon chain derived, for example, from a polymer of a mono-olefin wherein the polymer chain contains from 40 to 500 carbon atoms. Suitable polyolefins include those derived from olefins containing from 2 to 6 carbon atoms, in particular ethylene, propylene, butene-l and isoprene, but especially isobutene.
It has been observed, that during selection of the second lipophilic chain, a higher degree of olefinic unsaturation generally results in an increasing stability of the emulsion formed, and generally leads to a smaller droplet size in the emulsion. Accordingly, it is preferred that the second lipophilic chain (L2) be preferably a hydrocarbon chain comprising greater than 1, and more preferably greater than 2 or more preferably 3, olefenic unsaturated bonds. It is also preferred that the second lipophilic chain comprise a long chain hydrocarbon comprising between 8 - 36 carbon atoms, preferably 10 - 26 carbon atoms and most preferably between 16 and 22 carbon atoms. A preferred material of use as the second lipophilic chain is based on the residual of a polyunsaturated fatty acid. Polyunsaturated fatty acids include fatty acids having an average olefinic unsaturation level of greater than 1 (e.g. 1.1), and can include mixtures of fatty acids.
Examples of these fatty acids include linoleic acid (cis,cis-9,12-octadecadienoic acid), linolenic acid (cis,cis,cis-9,12,14-octadecatrienoic acid), or mixtures thereof and therebetween, and rusic acid.
Further, it is preferred that the second lipophilic chain be an aliphatic chain, which preferably is not significantly branched.
The hydrophilic species (R) of the preferred emulsifying agent of the current invention is hydrogen or a hydrophilic group. However, when x is 0, R may be a second direct link to M1. When R is a hydrophilic group, it is preferred that the group be polar in character and suitably comprise an organic residue having a molecular weight not exceeding 450 and preferably not exceeding 200. In determining the aforementioned molecular weights any contribution from an ionic moiety is to be disregarded.
The organic residue is desirably monomeric although oligomeric groupings - containing, for example, not more than about 10 repeat units - may be employed provided that the molecular weight thereof is within the aforementioned limit. In a preferred embodiment suitable monomeric groupings may be chosen from the group comprising hydroxyl, amino hydroxyl, alkyl hydroxy pyridine, alkyl hydroxy pyrimidine and polyhydroxy carboxylic acid.
A preferred formula for R is -(CH2)jOH wherein j is 1, 2 or 3.
Preferably, either of the two linking moieties (M1 or MZ) may comprise hydroxyl, amino, carboxylic acid or carboxylic acid anhydride groups, and each acts to link either the first and second lipophilic chains to the hydrophilic moiety.
Conveniently, the first linking moiety (M1) and the first lipophilic chain (L1) may be present in the same species. For example, the first linking moiety and the first lipophilic chain may both be a poly[alk(en)yl]
succinic anhydride based compound (or its acid form) in which a lipophilic carbon chain is terminated by a succinic anhydride linking moiety. A preferred material of use in ~1~2~1 this embodiment is a polyisobutylene succinic anhydride based material.
Similarly, the second linking moiety (M2) and the hydrophilic species may be combined into a common species.
For example, the second linking moiety and the hydrophilic species may form a material, such as, a dialkanolamine.
It is preferred that the emulsifying agent of the current invention comprises ester linkages between the second linking moiety (M2) and the second lipophilic chain (L2). It is also preferred that the emulsifying agent comprises ester, amide or imide linkages between the first linking moiety (M1) and the first lipophilic chain (L1).
Preferably, M1 has one of the following formulas:
=~ \ _ O -- ( CH2 ) n OH O
when x is 0 ~ O in Formula I
or o OH O
Preferably, M2 has the formula:
-- O -- C
\
One particularly preferred emulsifying agent has the formula IA:
L1 Formula IA
~ R
O=\ \j~ O ~ ( CH2 ) n ~ N /O
OH O (CH2) m ~ O ~ C
216~
g where L1, L2 and R are as defined hereinabove, and n is 2 1, and m 2 0.
Further, one particularly preferred emulsifying agent has the formula IA shown above, wherein L1 and M1 combined are the residual of polyisobutylene succinic anhydride having a backbone structure of less than 500 carbon atoms in the polyisobutylene portion, n and m are 1, R is hydrogen or -(CH2)jOH wherein j is 1, 2 or 3, and L2 is linoleic acid or linolenic acid, or mixtures thereof, or rusic acid.
Formation of the emulsifying agent of the current invention may be effected by conventional procedures depending upon the chemical nature of the lipophilic chains and hydrophilic species involved. Commonly this would involve (1) reaction of the first lipophilic chain with the first linking moiety, (2) condensation of the hydrophilic species containing the second linking moiety, with the first linking moiety and (3) derivatization of the second lipophilic chain with the second linking moiety.
For example where the first lipophilic chain and first linking moiety together comprise a poly[alk(en)yl] succinic anhydride based compound and the hydrophilic species/second linking moiety together are a diaIkanolamine the anhydride group can be caused to react with the hydroxyl or amino group by heating the two components together in a suitable solvent, in the presence of a catalyst if desired. Where the succinic anhydride and amino groupings are present in a 1:1 molar ratio there is imide/ amide formation. The compound so formed may then be heated with a cis-polyunsaturated fatty acid to promote esterification.
ICICAN 816 ~1624~1 This reaction sequence may be represented as follows:
-_D + ~O (C z)~ ~ (C~2) L~ ,R
O~r ~ O -_ (C~Z~ 0 v ~ L cr~o H
C)--~ O-~C~ C~Z~--O-C~\LZ
wherein L1, L2, R, m and n are as previously defined.
The emulsifying agents of the present invention as described hereinabove, are suitable for use in emulsion explosive compositions. These compositions comprise a continuous water-immiscible, hydrocarbon phase, a discontinuous aqueous salt or eutectic phase and at least one emulsifying agent, wherein the emulsifying agent is as described hereinabove.
Typically the total emulsifier component of the emulsion comprises up to 5% by weight of the emulsion. A
higher proportion of the emulsifier component may be used and may serve as a supplemental fuel for the composition, but in general it is not necessary to add more than 5% by weight of emulsifier component to achieve the desired effect. Stable emulsions can be formed using relatively low levels of emulsifier component and for reasons of economy it is preferable to keep to the minimum amounts of emulsifier necessary to achieve the desired effect. The preferred level of emulsifier component used in the practise of the present invention is preferably in the range of from 0.4 to 3.0% by weight of the emulsion, and more preferably in the range of between 1.5 to 2.5% by weight.
ICICAN 816 21~2~1 The remaining components of the emulsion explosive composition are described in detail in the prior art.
However, the following describes, in general, typical formulation parameters for emulsion explosives.
The oxidizer salt for use in the discontinuous phase of the emulsion is preferably selected from the group consisting of ammonium and alkali and alkaline earth metal nitrates and perchlorates and mixtures thereof. It is particularly preferred that the oxidiser salt is ammonium nitrate or a mixture of ammonium nitrate and sodium nitrate or calcium nitrate.
The oxidiser salt for use in the discontinuous phase of the emulsion may further contain a melting point depressant. Suitable melting point depressants for use with ammonium nitrate in the discontinuous phase include inorganic salts such as lithium nitrate, sodium nitrate, potassium nitrate; alcohols such as methyl alcohol, ethylene glycol, glycerol, mannitol, sorbitol, pentaerythritol; carbohydrates such as sugars, starches and dextrins; aliphatic carboxylic acids and their salts such as formic acid, acetic acid, ammonium formate, sodium formate, sodium acetate, and ammonium acetate; glycine;
chloracetic acid; glycolic acid; succinic acid; tartaric acid; adipic acid; lower aliphatic amides such as formamide, acetamide and urea; urea nitrate; nitrogenous substances such as nitroguanidine, guanidine nitrate, methylamine nitrate, and ethylene diamine dinitrate; and mixtures thereof.
Typically the discontinuous phase of the emulsion comprises 60 to 97% by weight of the emulsion explosive, and preferably 86 to 95% by weight of the emulsion explosive.
The continuous water-immiscible phase of the emulsion comprises an organic fuel. Preferred organic fuels for use in the continuous phase include aliphatic, alicyclic and aromatic compounds and mixtures thereof which are in the liquid state at the formulation temperature. Suitable organic fuels may be chosen from fuel oil, diesel oil, distillate, furnace oil, kerosene, naphtha, waxes (e.g.
microcrystalline wax, paraffin wax and slack wax), paraffin oils, benzene, toluene, xylenes, asphaltic materials, polymeric oils such as the low molecular weight polymers of olefins, animal oils, fish oils, vegetable oils, corn oil and other mineral, hydrocarbon or fatty oils, and mixtures thereof. Preferred organic fuels are liquid hydrocarbons generally referred to as petroleum distillate, such as gasoline, kerosene, fuel oils and paraffin oils.
Typically, the continuous water-immiscible fuel phase of the emulsion (including emulsifier) comprises more than 3 to less than 30% by weight of the emulsion, and preferably from 5 to 15% by weight of the emulsion. For acceptable production properties, however, the total continuous water-immiscible fuel phase of the prior art emulsions typically comprised greater than 5% by weight of the emulsion in order to effectively process the emulsion in a "Jet" mixer commonly used for production.
Because of the improved emulsifying efficiency (the ability of emulsifying agent to form an emulsion) of the emulsifiers of the present invention, however, it is now possible to reduce the emulsifying agent level of the emulsion, and thus lower the level of total fuel phase required for production processing of the emulsion.
Accordingly, with the emulsifiers of the present invention, the amount of fuel oil required for acceptable production properties is reduced, thereby creating emulsions having a lower total fuel oil phase content. This permits the practical production of emulsion explosives which are essentially oxygen balanced (e.g. having less than 5% total fuel oil phase content), or which are not significantly oxygen deficient.
Accordingly, in a preferred embodiment, the emulsion comprises a combined total level of the continuous water-immiscible hydrocarbon phase and the emulsifying agent ofless than or equal to 5% by weight of the emulsion.
If desired, optional additional fuel materials hereinafter referred to as secondary fuels may be mixed into the emulsion. Examples of such secondary fuels include finely divided materials such as: sulphur, aluminium, carbonaceous materials such as gilsonite, comminuted coke or charcoal, carbon black, resin acids such as abietic acid, sugars such as glucose or dextrose and other vegetables products such as starch, nut meal, grain meal and wood pulp; and mixtures thereof.
Typically, the optional secondary fuel component of the emulsion is used in an amount up to 30% by weight based on the weight of the emulsion.
The emulsion may be sensitised to provide an emulsion explosive by combination with a self-explosive compound or composition or by the addition of finely dispersed voiding agents. Voiding agents may also be used to vary the density and/or the sensitivity of an explosive composition.
For example, the explosive composition may comprise a discontinuous gaseous component as a voiding agent.
Methods of incorporating a gaseous component and the enhanced sensitivity of explosive compositions comprising gaseous components are well known to those skilled in the art. The gaseous components may, for example, be incorporated into the explosive composition as fine gas bubbles dispersed through the composition, as hollow particles which are often referred to as microballoons or microspheres, as porous particles of e.g. perlite or mixtures thereof.
A discontinuous phase of fine gas bubbles may be incorporated into the explosive composition by mechanical agitation, injection or bubbling the gas through the composition or by chemical generation of the gas in situ.
Suitable chemicals for the in situ generation of gas bubbles include peroxides, such as hydrogen peroxide, nitrites, such as sodium nitrite, nitrosoamines, such as N,N'-dinitrosopentamethylenetetramine, alkali metal borohydrides, such as sodium borohydride, and carbonates, such as sodium carbonate. Preferred chemicals for the in situ generation of gas bubbles are nitrous acid and its salts which decompose under conditions of acid pH to ICICAN 816 2162~1~
produce nitrogen gas bubbles. Preferred nitrous acid salts include alkali metal nitrites, such as sodium nitrite.
These can be incorporated as an aqueous solution, a pre-emulsified aqueous solution in an oil phase or as a water-in-oil micro emulsion comprising oil and nitrite solution.
Catalytic agents such as thiocyanate or thiourea may be used to accelerate the decomposition of a nitrite gassing agent. Suitable small hollow particles include small hollow microspheres of glass or resinous materials, such as phenol-formaldehyde, urea-formaldehyde and copolymers of vinylidene chloride and acrylonitrile. Suitable porous materials include expanded minerals such as perlite and expanded polymers such as polystyrene.
Gas bubbles may also be added to the emulsion as a preformed foam of air, carbon dioxide, nitrogen or nitrous oxide in liquid, preferably an oil phase.
As described hereinabove, preferred emulsion explosive compositions formed using the emulsion of the current invention are preferably oxygen balanced or not significantly oxygen deficient. Additional components may be added to the explosive composition to control the oxygen balance of the explosive composition such as solid particulate ammonium nitrate as powder or porous prill.
The emulsion may also be blended with ANFO.
The emulsions and emulsion explosives of the present invention are, preferably made by preparing a first premix of water and inorganic oxidiser salt and a second premix of fuel/oil and a mixture of the surfactant and co-surfactant (if desired) in accordance with the present invention. The aqueous premix is heated to ensure dissolution of the salts and the fuel premix is heated as may be necessary to provide liquidity. The premixes are blended together and emulsified. Common emulsification methods use a mechanical blade mixer, rotating drum mixer, or a passage through an in-line static mixer. Thereafter, the property modifying materials such as, for example, glass microspheres, may be added along with any auxiliary fuel, e.g. aluminium particles or any desired particulate ammonium nitrate.
Accordingly in further aspect, the present invention provides a method of manufacturing an emulsion explosive comprising emulsifying an oxidiser salt phase into an emulsifier/fuel mixture using the emulsifying agent of the current invention and then adding a sensitising agent.
In a further aspect, the present invention also provides a method of blasting comprising placing an emulsion explosive as described hereinabove in operative contact with an initiating system including a detonator and initiating said detonator and thereby said emulsion explosive.
Examples The emulsifier invention of the current application will now be further explained with reference to the following examples:
Example l Triethanolamine (32 parts by volume) was added to polyiso-butylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Linoleic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C for a further 1 hour until completion of the reaction. Paraffin oil (120 parts by volume) was then added to the reaction to form a 50% active emulsifying agent.
Example 2 Diethanolamine (32 parts by volume) was added to polyiso-butylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Linoleic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C for a further 1 hour until completion of the reaction. Paraffin oil (120 parts by volume) was then added to the reaction to form a 50% active emulsifying agent.
ICICAN 816 21624~1 .
Example 3 Aminopropylene glycol (20 parts by volume) was added to polyisobutylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Linoleic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C for a further 1 hour until completion of the reaction. Paraffin oil (120 parts by volume) was then added to the reaction to form a 50% active emulsifying agent.
Example 4 Triethanolamine (32 parts by volume) was added to polyiso-butylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Linolenic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C
for a further 1 hour until completion of the reaction.
Paraffin oil (120 parts by volume) was then added to the reaction to form a 50% active emulsifying agent.
Comparative Example 5 (CE 5) Triethanolamine (32 parts by volume) was added to polyiso-butylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Oleic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C for a further 1 hour until completion of the reaction. Paraffin oil (120 parts by volume) was then added to the reaction to form a 50% active emulsifying agent.
Comparative Example 6 Triethanolamine (32 parts by volume) was added to polyiso-butylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Stearic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C for a further 1 hour until completion of the reaction. Paraffin oil (120 parts by volume) was then added to the reaction to ICICAN 816 216241 i form a 50% active emulsifying agent.
Example 7 A water-in-oil emulsion was formed by slowly adding the emulsifying agent of Example 1 and fuel oil mixture to an aqueous ammonium nitrate solution. The emulsion formed was of the following composition:
Component Proportion (wt/%) Example 7A Example 7B
ammonium nitrate 79.05 79.05 water 16.20 16.20 emulsifying agent:
as per Example 1 2.30 as per Example 4 2.30 fuel oil 2.45 2.45 ~5 Comparative Example 8 A water-in-oil emulsion was formed by slowly adding the emulsifying agent of Comparative Example 5 and fuel oil mixture to an aqueous ammonium nitrate solution. The emulsion formed was of the following composition:
Component ProPortion (wt/%) ammonium nitrate 79.05 water 16.20 emulsifying agent:
as per CE 5 2.30 fuel oil 2.45 21~2411 Comparative Example 9 A water-in-oil emulsion was formed by slowly adding the emulsifying agent of Comparative Example 6 (CE6) and fuel oil mixture to an aqueous ammonium nitrate solution.
The emulsion formed was of the following composition:
Component Proportion (wt/%) ammonium nitrate 79.05 water 16.20 emulsifying agent 2.30 (as per CE6) fuel oil 2.45 The water-in-oil emulsions of Examples 7A and 7B, and Comparative Examples 8 and 9 were subjected to microscopic and physical examination and the results are recorded in Table 1.
~162~11 Example No.
Criterion 7A 7B CE 8 CE 9 Unsaturation 2 3 1 0 level of L2 in Formula 1 Droplet Size<2 <2 approx >3 (micron) 2 Viscosity 272,000300,000 252,000247,000 (cps) Conductivity<100 <100 >1000 >2000 (pmho/m) Interfacial approx. approx. approx. approx.
Tension16.5 16.5 16.5 16.5 (dynes/cm) Stability2 v. good v. good good poor (at 6 weeks) Stability good at good at fair at poor at with AN36 weeks 6 weeks 4 weeks 1 week Notes: (1 - viscosity measured at 20~C using a number 7 brookfield spindle at 50 rpm) (2 - stability measured by microscopically examining emulsion stored at ambient temperature) (3 - stability of emulsions mixed with 30% by weight ammonium nitrate prill) The emulsions of Examples 7A and 7B comprise emulsifiers having a second lipophilic chain (L2) derived from polyunsaturated fatty acids, having olefinic unsaturation, such as linoleic acid or linolenic acid. The emulsion of Comparative Examples 8 and 9 comprise an emulsifier having a second lipophilic chain (L2) derived from a mono-unsaturated fatty acid (oleic acid) or a saturated fatty acid (stearic acid). The results recorded in Table 1 illustrate the superior storage stability of emulsions of the current invention even though the three examples all have essentially constant interfacial tension.
Comparative Example 10 A water-in-oil emulsion was formed by slowly adding an emulsifying agent of the prior art and fuel oil mixture to an aqueous ammonium nitrate solution. The emulsifying agent of the prior art comprised a condensation product of the reaction of succinic anhydride with an alpha-olefin mixed with sorbitan mono-oleate. The emulsion formed was of the following composition:
ComponentProportion (wt/%) ammonium nitrate76.20 water 19.05 emulsifying agent 2.30 fuel oil 2.45 Comparative Example 11 A water-in-oil emulsion was formed by slowly adding an emulsifying agent of the prior art comprising a condensation product of the reaction of succinic anhydride with an alpha-olefin and fuel oil mixture to an aqueous ammonium nitrate solution. The emulsion formed was of the following composition:
ICICAN 816 ~16~;41~
ComponentProportion (wt/%
ammonium nitrate 73.90 water 18.50 emulsifying agent 2.30 fuel oil 5.30 The emulsion of Example 7A which comprises the emulsifying agent of the current invention were compared with the emulsions of Comparative Examples CE10 and CE11 which comprise emulsifying agents of the prior art. The emulsions were hand mixed with ammonium nitrate prills and then subjected to a higher shear stress by mixing at about 60 rpm in a Hobart mixer at 60~C for 5 minutes. The mixed material was stored at ambient temperature and periodically subjected to photomicroscopic examination. The results are shown in Table 2. It can be seen that the emulsion of Example 7 showed greater stability than the emulsion of either CE10 or CEll.
Table 2: Stability with Ammonium Nitrate Rate of Emulsion Formulation*
Crystallization**
Ex. 7 CE 10 CE 11 Time: 2 days 1 4.5 1.5 1 week 1.5 5 1.5 2 weeks 1.5 5 2 * - Photomicroscopically examined emulsion mixed with 30% by weight ammonium nitrate prill ** - Rate of Crystallization (0 = no crystallization, 5 = completely crystallized) Having described specific embodiments of the present invention, it will be understood that modifications thereof may be suggested to those skilled in the art, and it is intended to cover all such modifications as fall within the scope of the appended claims.
Description of the Related Art Water-in-fuel and melt-in-fuel emulsion explosives are well known in the explosives industry and are routinely used in civilian excavation, mining and quarrying. Water-in-fuel emulsions comprise a discontinuous phase of droplets of an oxygen supplying component such as an aqueous oxidiser salt solution dispersed in a continuous phase of oils and/or waxes in the presence of one or more emulsifying agents. The oxygen-supplying discontinuous phase of a melt-in-fuel emulsion comprises only a small proportion of water or adventitious water only. The discontinuous phase may be a eutectic composition, that is the melting point of the composition is either at the eutectic or in the region of the eutectic of the component salts of the discontinuous phase. Where used herein the term emulsion refers to both water-in-fuel and melt-in-fuel emulsions.
In general the emulsions suitable for use in emulsion explosives are relatively inert until mixed with sensitizing agents such as self-detonable compounds (e.g.
nitroglycerine) or void material such as glass microballoons, gas bubbles or the like.
Water-in-fuel emulsion explosives compositions were first disclosed by Bluhm in United States Patent 3,447,978 and comprise (a) a discontinuous aqueous phase comprising -21~2~11 discrete droplets of an aqueous solution of inorganic oxygen-releasing salts; (b) a continuous water-immiscible organic phase throughout which the droplets are dispersed and (c) an emulsifier which forms an emulsion of the S droplets of oxidizer salt solution throughout the continuous organic phase. They may also include sensitizing agents such as a discontinuous gaseous phase.
Subsequently, numerous documents have been published which provide modifications and/or improvements over the formulations originally described by Bluhm.
A key component in the formulation of an emulsion explosive composition is the selection of the proper emulsifying agent. The type of emulsifying agent chosen will have an effect on many properties of the emulsion including, for example, the ease of formation of the emulsion, the discontinuous phase droplet size and the tendency of the droplets to crystallise or coalesce. These properties are particularly relevant to the storage stability of the emulsion and ultimately, the performance of the composition as an explosive.
Australian patent application no. 40006/85 (Cooper &
Baker) discloses emulsion explosive compositions in which the emulsifier is a reaction product of a poly[alk(en)yl]
species (e.g. an alkylated succinic anhydride) and amines such as ethylene diamine, diethylene triamine and mono- and di-ethanolamines.
McKenzie in US patent No. 4,931,110 describes the use of a bis(alkanolamine or polyol) amide and/or ester derivatives of, for example, polyalk(en)yl succinic anhydride compounds as suitable emulsifying agents.
Polyalk(en)yl succinic anhydride compounds are described by Baker in Canadian patent No. 1,244,463.
Forsberg et al. in US patent No. 4,840,687 describe an emulsion explosive composition wherein the emulsifier is a nitrogen-containing emulsifier derived from at least one carboxylic acylating agent, a polyamine and an acidic compound.
-Additionally, Chattopadhyay, in Canadian patent application No. 2,076,987 describes the use of a mixed emulsifying agent system for emulsion explosives comprising a surfactant and co-surfactant, each having branched chain hydrocarbon tails.
However, the identification of additional emulsifying agents is still desirable in order to lead to improved emulsifying agent or emulsion properties.
Emulsifying agents perform several functions during the formation and subsequent stabilisation of an emulsion explosive composition. As an emulsion is being formed the emulsifying agent must be able to lower the interfacial tension between the discontinuous and continuous phases and thus stabilize the interfaces between the oxidiser salt droplets and the fuel. The emulsifying agent must also form a structured bilayer at the interface to aid suppression of droplet coalescence and inhibit the crystallisation of salts in the droplets. It is also important that the emulsifying agent be able to preserve bilayer integrity dynamically when an emulsion explosive is subjected to shear stress, such as the shear stress which occurs during pumping.
Providing a single emulsifying agent which satisfies all these criteria is not straightforward. Accordingly, an emulsifier system is often employed which contains a mixture of emulsifying agents; each of which satisfies different criteria. A particularly preferred mixed emulsifier system of the prior art is described in the aforementioned Cooper & Baker and Chattopadhyay references and by Yates et al. in US patent No. 4,710,248 which describes the use of a derivatized polyisobutene succinic anhydride surfactant in combination with a co-surfactant such as sorbitan monooleate. The emulsifying agents of the prior art are relatively effective in performing some functions but improvements are still sought.
For example, it has proved particularly difficult to identify suitable emulsifying agents for certain types of emulsions for use in emulsion explosives compositions. In particular, emulsifying agents of the prior art have proved inadequate for the formation of emulsions which can be formed into stable, oxygen balanced emulsion explosives compositions. In the field of emulsion explosives, a S composition is said to be oxygen balanced at the point at which adequate oxygen from the components is made available for the explosive detonation to go to completion, leaving no unreacted material. Oxygen balanced compositions are particularly desirable because they provide maximum energy and minimum fume.
Many emulsion explosive compositions currently in use are oxygen negative, that is there is insufficient oxidizer salt present to achieve total reaction of all materials. In these oxygen negative formulations, the ratio of oxidiser phase to fuel oil phase is commonly between 90:10 and 94:6 and the detonation of these materials tends to produce toxic NOX fumes. Ideally, maximum energy release and minimum fume would be provided by an oxygen balanced composition. Typically, these oxygen balanced compositions have an oxidiser phase:fuel oil phase ratio of between about 95:5 and 96:4. However oxygen balanced compositions can be difficult to prepare, in practice, because of the lack of suitable emulsifying agents which can stabilize such low fuel phase-content compositions.
It is thus an object of the present invention to provide an improved emulsifying agent capable of providing the desired properties described hereinabove.
Summary of the Invention It has now been found that a particular class of emulsifier is particularly suitable for use in emulsion explosive compositions, and in particular, for use in oxygen balanced emulsion explosive compositions.
Accordingly, the present invention provides an emulsifying agent suitable for use in an emulsion explosive composition comprising a hydrophilic species, a first lipophilic chain ICICAN 816 ~ 4 ~ ~
-which is attached to said hydrophilic species by a first linking moiety, and a second lipophilic chain which is attached to said hydrophilic species by a second linking moiety, and wherein said second lipophilic chain has more than one olefinic unsaturated bond in its hydrocarbon chain.
As is known by those skilled in the art, the degree of olefinic unsaturation for the second lipophilic chain may be an average value for the individual lipophilic molecules. Accordingly, the level of unsaturation of the second lipophilic chain may approach the value of 1, but preferably, the second lipophilic chain comprises at least two olefinic unsaturated bonds in its hydrocarbon chain, and preferably these two unsaturated bonds are separated by at least one saturated carbon bond (e.g. -CH2-).
Further, the current invention also provides an emulsion suitable for use in an emulsion explosive composition having a continuous hydrocarbon phase, a discontinuous aqueous salt or eutectic phase, and at least one emulsifying agent, wherein said emulsifying agent is an emulsifying agent as described hereinabove with respect to the present invention.
Description of the Preferred Embodiments In a particularly preferred embodiment the emulsifying agent is as described hereinabove with respect to the current invention, and has the structure shown for formula I;
L1 \ /Rx M1 ~ N Formula I
\(CHz)m - M2 L2 wherein L1 is a first lipophilic chain, L2 is a second, unsaturated lipophilic chain having an olefinic unsaturated level greater 21~2411 than 1, R is hydrogen or a hydrophilic group, or a direct bond to M1 when x is 0, M1 is an ester, amide or imide linkage, M2 is an ester linkage, and m is 2 O, and x is O or 1.
The first lipophilic chain (L1) may be either monomeric or polymeric in nature. The chain structure should incorporate a backbone sequence of at least 10 and preferably not more than 500 linked atoms. These linked atoms may be entirely carbon atoms or they may be predominantly carbon atoms interrupted by hetero atoms such as oxygen or nitrogen. A preferred type of first lipophilic chain is a saturated or unsaturated hydrocarbon chain derived, for example, from a polymer of a mono-olefin wherein the polymer chain contains from 40 to 500 carbon atoms. Suitable polyolefins include those derived from olefins containing from 2 to 6 carbon atoms, in particular ethylene, propylene, butene-l and isoprene, but especially isobutene.
It has been observed, that during selection of the second lipophilic chain, a higher degree of olefinic unsaturation generally results in an increasing stability of the emulsion formed, and generally leads to a smaller droplet size in the emulsion. Accordingly, it is preferred that the second lipophilic chain (L2) be preferably a hydrocarbon chain comprising greater than 1, and more preferably greater than 2 or more preferably 3, olefenic unsaturated bonds. It is also preferred that the second lipophilic chain comprise a long chain hydrocarbon comprising between 8 - 36 carbon atoms, preferably 10 - 26 carbon atoms and most preferably between 16 and 22 carbon atoms. A preferred material of use as the second lipophilic chain is based on the residual of a polyunsaturated fatty acid. Polyunsaturated fatty acids include fatty acids having an average olefinic unsaturation level of greater than 1 (e.g. 1.1), and can include mixtures of fatty acids.
Examples of these fatty acids include linoleic acid (cis,cis-9,12-octadecadienoic acid), linolenic acid (cis,cis,cis-9,12,14-octadecatrienoic acid), or mixtures thereof and therebetween, and rusic acid.
Further, it is preferred that the second lipophilic chain be an aliphatic chain, which preferably is not significantly branched.
The hydrophilic species (R) of the preferred emulsifying agent of the current invention is hydrogen or a hydrophilic group. However, when x is 0, R may be a second direct link to M1. When R is a hydrophilic group, it is preferred that the group be polar in character and suitably comprise an organic residue having a molecular weight not exceeding 450 and preferably not exceeding 200. In determining the aforementioned molecular weights any contribution from an ionic moiety is to be disregarded.
The organic residue is desirably monomeric although oligomeric groupings - containing, for example, not more than about 10 repeat units - may be employed provided that the molecular weight thereof is within the aforementioned limit. In a preferred embodiment suitable monomeric groupings may be chosen from the group comprising hydroxyl, amino hydroxyl, alkyl hydroxy pyridine, alkyl hydroxy pyrimidine and polyhydroxy carboxylic acid.
A preferred formula for R is -(CH2)jOH wherein j is 1, 2 or 3.
Preferably, either of the two linking moieties (M1 or MZ) may comprise hydroxyl, amino, carboxylic acid or carboxylic acid anhydride groups, and each acts to link either the first and second lipophilic chains to the hydrophilic moiety.
Conveniently, the first linking moiety (M1) and the first lipophilic chain (L1) may be present in the same species. For example, the first linking moiety and the first lipophilic chain may both be a poly[alk(en)yl]
succinic anhydride based compound (or its acid form) in which a lipophilic carbon chain is terminated by a succinic anhydride linking moiety. A preferred material of use in ~1~2~1 this embodiment is a polyisobutylene succinic anhydride based material.
Similarly, the second linking moiety (M2) and the hydrophilic species may be combined into a common species.
For example, the second linking moiety and the hydrophilic species may form a material, such as, a dialkanolamine.
It is preferred that the emulsifying agent of the current invention comprises ester linkages between the second linking moiety (M2) and the second lipophilic chain (L2). It is also preferred that the emulsifying agent comprises ester, amide or imide linkages between the first linking moiety (M1) and the first lipophilic chain (L1).
Preferably, M1 has one of the following formulas:
=~ \ _ O -- ( CH2 ) n OH O
when x is 0 ~ O in Formula I
or o OH O
Preferably, M2 has the formula:
-- O -- C
\
One particularly preferred emulsifying agent has the formula IA:
L1 Formula IA
~ R
O=\ \j~ O ~ ( CH2 ) n ~ N /O
OH O (CH2) m ~ O ~ C
216~
g where L1, L2 and R are as defined hereinabove, and n is 2 1, and m 2 0.
Further, one particularly preferred emulsifying agent has the formula IA shown above, wherein L1 and M1 combined are the residual of polyisobutylene succinic anhydride having a backbone structure of less than 500 carbon atoms in the polyisobutylene portion, n and m are 1, R is hydrogen or -(CH2)jOH wherein j is 1, 2 or 3, and L2 is linoleic acid or linolenic acid, or mixtures thereof, or rusic acid.
Formation of the emulsifying agent of the current invention may be effected by conventional procedures depending upon the chemical nature of the lipophilic chains and hydrophilic species involved. Commonly this would involve (1) reaction of the first lipophilic chain with the first linking moiety, (2) condensation of the hydrophilic species containing the second linking moiety, with the first linking moiety and (3) derivatization of the second lipophilic chain with the second linking moiety.
For example where the first lipophilic chain and first linking moiety together comprise a poly[alk(en)yl] succinic anhydride based compound and the hydrophilic species/second linking moiety together are a diaIkanolamine the anhydride group can be caused to react with the hydroxyl or amino group by heating the two components together in a suitable solvent, in the presence of a catalyst if desired. Where the succinic anhydride and amino groupings are present in a 1:1 molar ratio there is imide/ amide formation. The compound so formed may then be heated with a cis-polyunsaturated fatty acid to promote esterification.
ICICAN 816 ~1624~1 This reaction sequence may be represented as follows:
-_D + ~O (C z)~ ~ (C~2) L~ ,R
O~r ~ O -_ (C~Z~ 0 v ~ L cr~o H
C)--~ O-~C~ C~Z~--O-C~\LZ
wherein L1, L2, R, m and n are as previously defined.
The emulsifying agents of the present invention as described hereinabove, are suitable for use in emulsion explosive compositions. These compositions comprise a continuous water-immiscible, hydrocarbon phase, a discontinuous aqueous salt or eutectic phase and at least one emulsifying agent, wherein the emulsifying agent is as described hereinabove.
Typically the total emulsifier component of the emulsion comprises up to 5% by weight of the emulsion. A
higher proportion of the emulsifier component may be used and may serve as a supplemental fuel for the composition, but in general it is not necessary to add more than 5% by weight of emulsifier component to achieve the desired effect. Stable emulsions can be formed using relatively low levels of emulsifier component and for reasons of economy it is preferable to keep to the minimum amounts of emulsifier necessary to achieve the desired effect. The preferred level of emulsifier component used in the practise of the present invention is preferably in the range of from 0.4 to 3.0% by weight of the emulsion, and more preferably in the range of between 1.5 to 2.5% by weight.
ICICAN 816 21~2~1 The remaining components of the emulsion explosive composition are described in detail in the prior art.
However, the following describes, in general, typical formulation parameters for emulsion explosives.
The oxidizer salt for use in the discontinuous phase of the emulsion is preferably selected from the group consisting of ammonium and alkali and alkaline earth metal nitrates and perchlorates and mixtures thereof. It is particularly preferred that the oxidiser salt is ammonium nitrate or a mixture of ammonium nitrate and sodium nitrate or calcium nitrate.
The oxidiser salt for use in the discontinuous phase of the emulsion may further contain a melting point depressant. Suitable melting point depressants for use with ammonium nitrate in the discontinuous phase include inorganic salts such as lithium nitrate, sodium nitrate, potassium nitrate; alcohols such as methyl alcohol, ethylene glycol, glycerol, mannitol, sorbitol, pentaerythritol; carbohydrates such as sugars, starches and dextrins; aliphatic carboxylic acids and their salts such as formic acid, acetic acid, ammonium formate, sodium formate, sodium acetate, and ammonium acetate; glycine;
chloracetic acid; glycolic acid; succinic acid; tartaric acid; adipic acid; lower aliphatic amides such as formamide, acetamide and urea; urea nitrate; nitrogenous substances such as nitroguanidine, guanidine nitrate, methylamine nitrate, and ethylene diamine dinitrate; and mixtures thereof.
Typically the discontinuous phase of the emulsion comprises 60 to 97% by weight of the emulsion explosive, and preferably 86 to 95% by weight of the emulsion explosive.
The continuous water-immiscible phase of the emulsion comprises an organic fuel. Preferred organic fuels for use in the continuous phase include aliphatic, alicyclic and aromatic compounds and mixtures thereof which are in the liquid state at the formulation temperature. Suitable organic fuels may be chosen from fuel oil, diesel oil, distillate, furnace oil, kerosene, naphtha, waxes (e.g.
microcrystalline wax, paraffin wax and slack wax), paraffin oils, benzene, toluene, xylenes, asphaltic materials, polymeric oils such as the low molecular weight polymers of olefins, animal oils, fish oils, vegetable oils, corn oil and other mineral, hydrocarbon or fatty oils, and mixtures thereof. Preferred organic fuels are liquid hydrocarbons generally referred to as petroleum distillate, such as gasoline, kerosene, fuel oils and paraffin oils.
Typically, the continuous water-immiscible fuel phase of the emulsion (including emulsifier) comprises more than 3 to less than 30% by weight of the emulsion, and preferably from 5 to 15% by weight of the emulsion. For acceptable production properties, however, the total continuous water-immiscible fuel phase of the prior art emulsions typically comprised greater than 5% by weight of the emulsion in order to effectively process the emulsion in a "Jet" mixer commonly used for production.
Because of the improved emulsifying efficiency (the ability of emulsifying agent to form an emulsion) of the emulsifiers of the present invention, however, it is now possible to reduce the emulsifying agent level of the emulsion, and thus lower the level of total fuel phase required for production processing of the emulsion.
Accordingly, with the emulsifiers of the present invention, the amount of fuel oil required for acceptable production properties is reduced, thereby creating emulsions having a lower total fuel oil phase content. This permits the practical production of emulsion explosives which are essentially oxygen balanced (e.g. having less than 5% total fuel oil phase content), or which are not significantly oxygen deficient.
Accordingly, in a preferred embodiment, the emulsion comprises a combined total level of the continuous water-immiscible hydrocarbon phase and the emulsifying agent ofless than or equal to 5% by weight of the emulsion.
If desired, optional additional fuel materials hereinafter referred to as secondary fuels may be mixed into the emulsion. Examples of such secondary fuels include finely divided materials such as: sulphur, aluminium, carbonaceous materials such as gilsonite, comminuted coke or charcoal, carbon black, resin acids such as abietic acid, sugars such as glucose or dextrose and other vegetables products such as starch, nut meal, grain meal and wood pulp; and mixtures thereof.
Typically, the optional secondary fuel component of the emulsion is used in an amount up to 30% by weight based on the weight of the emulsion.
The emulsion may be sensitised to provide an emulsion explosive by combination with a self-explosive compound or composition or by the addition of finely dispersed voiding agents. Voiding agents may also be used to vary the density and/or the sensitivity of an explosive composition.
For example, the explosive composition may comprise a discontinuous gaseous component as a voiding agent.
Methods of incorporating a gaseous component and the enhanced sensitivity of explosive compositions comprising gaseous components are well known to those skilled in the art. The gaseous components may, for example, be incorporated into the explosive composition as fine gas bubbles dispersed through the composition, as hollow particles which are often referred to as microballoons or microspheres, as porous particles of e.g. perlite or mixtures thereof.
A discontinuous phase of fine gas bubbles may be incorporated into the explosive composition by mechanical agitation, injection or bubbling the gas through the composition or by chemical generation of the gas in situ.
Suitable chemicals for the in situ generation of gas bubbles include peroxides, such as hydrogen peroxide, nitrites, such as sodium nitrite, nitrosoamines, such as N,N'-dinitrosopentamethylenetetramine, alkali metal borohydrides, such as sodium borohydride, and carbonates, such as sodium carbonate. Preferred chemicals for the in situ generation of gas bubbles are nitrous acid and its salts which decompose under conditions of acid pH to ICICAN 816 2162~1~
produce nitrogen gas bubbles. Preferred nitrous acid salts include alkali metal nitrites, such as sodium nitrite.
These can be incorporated as an aqueous solution, a pre-emulsified aqueous solution in an oil phase or as a water-in-oil micro emulsion comprising oil and nitrite solution.
Catalytic agents such as thiocyanate or thiourea may be used to accelerate the decomposition of a nitrite gassing agent. Suitable small hollow particles include small hollow microspheres of glass or resinous materials, such as phenol-formaldehyde, urea-formaldehyde and copolymers of vinylidene chloride and acrylonitrile. Suitable porous materials include expanded minerals such as perlite and expanded polymers such as polystyrene.
Gas bubbles may also be added to the emulsion as a preformed foam of air, carbon dioxide, nitrogen or nitrous oxide in liquid, preferably an oil phase.
As described hereinabove, preferred emulsion explosive compositions formed using the emulsion of the current invention are preferably oxygen balanced or not significantly oxygen deficient. Additional components may be added to the explosive composition to control the oxygen balance of the explosive composition such as solid particulate ammonium nitrate as powder or porous prill.
The emulsion may also be blended with ANFO.
The emulsions and emulsion explosives of the present invention are, preferably made by preparing a first premix of water and inorganic oxidiser salt and a second premix of fuel/oil and a mixture of the surfactant and co-surfactant (if desired) in accordance with the present invention. The aqueous premix is heated to ensure dissolution of the salts and the fuel premix is heated as may be necessary to provide liquidity. The premixes are blended together and emulsified. Common emulsification methods use a mechanical blade mixer, rotating drum mixer, or a passage through an in-line static mixer. Thereafter, the property modifying materials such as, for example, glass microspheres, may be added along with any auxiliary fuel, e.g. aluminium particles or any desired particulate ammonium nitrate.
Accordingly in further aspect, the present invention provides a method of manufacturing an emulsion explosive comprising emulsifying an oxidiser salt phase into an emulsifier/fuel mixture using the emulsifying agent of the current invention and then adding a sensitising agent.
In a further aspect, the present invention also provides a method of blasting comprising placing an emulsion explosive as described hereinabove in operative contact with an initiating system including a detonator and initiating said detonator and thereby said emulsion explosive.
Examples The emulsifier invention of the current application will now be further explained with reference to the following examples:
Example l Triethanolamine (32 parts by volume) was added to polyiso-butylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Linoleic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C for a further 1 hour until completion of the reaction. Paraffin oil (120 parts by volume) was then added to the reaction to form a 50% active emulsifying agent.
Example 2 Diethanolamine (32 parts by volume) was added to polyiso-butylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Linoleic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C for a further 1 hour until completion of the reaction. Paraffin oil (120 parts by volume) was then added to the reaction to form a 50% active emulsifying agent.
ICICAN 816 21624~1 .
Example 3 Aminopropylene glycol (20 parts by volume) was added to polyisobutylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Linoleic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C for a further 1 hour until completion of the reaction. Paraffin oil (120 parts by volume) was then added to the reaction to form a 50% active emulsifying agent.
Example 4 Triethanolamine (32 parts by volume) was added to polyiso-butylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Linolenic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C
for a further 1 hour until completion of the reaction.
Paraffin oil (120 parts by volume) was then added to the reaction to form a 50% active emulsifying agent.
Comparative Example 5 (CE 5) Triethanolamine (32 parts by volume) was added to polyiso-butylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Oleic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C for a further 1 hour until completion of the reaction. Paraffin oil (120 parts by volume) was then added to the reaction to form a 50% active emulsifying agent.
Comparative Example 6 Triethanolamine (32 parts by volume) was added to polyiso-butylene succinic anhydride (300 parts by volume;
ex-Mobil) at 100~C and the components stirred together for one hour. Stearic acid (55 parts) was slowly added to the hot reaction mixture and stirring continued at 100~C for a further 1 hour until completion of the reaction. Paraffin oil (120 parts by volume) was then added to the reaction to ICICAN 816 216241 i form a 50% active emulsifying agent.
Example 7 A water-in-oil emulsion was formed by slowly adding the emulsifying agent of Example 1 and fuel oil mixture to an aqueous ammonium nitrate solution. The emulsion formed was of the following composition:
Component Proportion (wt/%) Example 7A Example 7B
ammonium nitrate 79.05 79.05 water 16.20 16.20 emulsifying agent:
as per Example 1 2.30 as per Example 4 2.30 fuel oil 2.45 2.45 ~5 Comparative Example 8 A water-in-oil emulsion was formed by slowly adding the emulsifying agent of Comparative Example 5 and fuel oil mixture to an aqueous ammonium nitrate solution. The emulsion formed was of the following composition:
Component ProPortion (wt/%) ammonium nitrate 79.05 water 16.20 emulsifying agent:
as per CE 5 2.30 fuel oil 2.45 21~2411 Comparative Example 9 A water-in-oil emulsion was formed by slowly adding the emulsifying agent of Comparative Example 6 (CE6) and fuel oil mixture to an aqueous ammonium nitrate solution.
The emulsion formed was of the following composition:
Component Proportion (wt/%) ammonium nitrate 79.05 water 16.20 emulsifying agent 2.30 (as per CE6) fuel oil 2.45 The water-in-oil emulsions of Examples 7A and 7B, and Comparative Examples 8 and 9 were subjected to microscopic and physical examination and the results are recorded in Table 1.
~162~11 Example No.
Criterion 7A 7B CE 8 CE 9 Unsaturation 2 3 1 0 level of L2 in Formula 1 Droplet Size<2 <2 approx >3 (micron) 2 Viscosity 272,000300,000 252,000247,000 (cps) Conductivity<100 <100 >1000 >2000 (pmho/m) Interfacial approx. approx. approx. approx.
Tension16.5 16.5 16.5 16.5 (dynes/cm) Stability2 v. good v. good good poor (at 6 weeks) Stability good at good at fair at poor at with AN36 weeks 6 weeks 4 weeks 1 week Notes: (1 - viscosity measured at 20~C using a number 7 brookfield spindle at 50 rpm) (2 - stability measured by microscopically examining emulsion stored at ambient temperature) (3 - stability of emulsions mixed with 30% by weight ammonium nitrate prill) The emulsions of Examples 7A and 7B comprise emulsifiers having a second lipophilic chain (L2) derived from polyunsaturated fatty acids, having olefinic unsaturation, such as linoleic acid or linolenic acid. The emulsion of Comparative Examples 8 and 9 comprise an emulsifier having a second lipophilic chain (L2) derived from a mono-unsaturated fatty acid (oleic acid) or a saturated fatty acid (stearic acid). The results recorded in Table 1 illustrate the superior storage stability of emulsions of the current invention even though the three examples all have essentially constant interfacial tension.
Comparative Example 10 A water-in-oil emulsion was formed by slowly adding an emulsifying agent of the prior art and fuel oil mixture to an aqueous ammonium nitrate solution. The emulsifying agent of the prior art comprised a condensation product of the reaction of succinic anhydride with an alpha-olefin mixed with sorbitan mono-oleate. The emulsion formed was of the following composition:
ComponentProportion (wt/%) ammonium nitrate76.20 water 19.05 emulsifying agent 2.30 fuel oil 2.45 Comparative Example 11 A water-in-oil emulsion was formed by slowly adding an emulsifying agent of the prior art comprising a condensation product of the reaction of succinic anhydride with an alpha-olefin and fuel oil mixture to an aqueous ammonium nitrate solution. The emulsion formed was of the following composition:
ICICAN 816 ~16~;41~
ComponentProportion (wt/%
ammonium nitrate 73.90 water 18.50 emulsifying agent 2.30 fuel oil 5.30 The emulsion of Example 7A which comprises the emulsifying agent of the current invention were compared with the emulsions of Comparative Examples CE10 and CE11 which comprise emulsifying agents of the prior art. The emulsions were hand mixed with ammonium nitrate prills and then subjected to a higher shear stress by mixing at about 60 rpm in a Hobart mixer at 60~C for 5 minutes. The mixed material was stored at ambient temperature and periodically subjected to photomicroscopic examination. The results are shown in Table 2. It can be seen that the emulsion of Example 7 showed greater stability than the emulsion of either CE10 or CEll.
Table 2: Stability with Ammonium Nitrate Rate of Emulsion Formulation*
Crystallization**
Ex. 7 CE 10 CE 11 Time: 2 days 1 4.5 1.5 1 week 1.5 5 1.5 2 weeks 1.5 5 2 * - Photomicroscopically examined emulsion mixed with 30% by weight ammonium nitrate prill ** - Rate of Crystallization (0 = no crystallization, 5 = completely crystallized) Having described specific embodiments of the present invention, it will be understood that modifications thereof may be suggested to those skilled in the art, and it is intended to cover all such modifications as fall within the scope of the appended claims.
Claims (27)
1. An emulsifying agent suitable for use in an emulsion explosive composition comprising a hydrophilic species, a first lipophilic chain which is attached to said hydrophilic species by a first linking moiety, and a second lipophilic chain which is attached to said hydrophilic species by a second linking moiety, and wherein said second lipophilic chain has more than one olefinic unsaturated bond in its hydrocarbon chain.
2. An emulsifying agent as claimed in claim 1 wherein said second lipophilic chain comprises at least two olefinic unsaturated bonds in its hydrocarbon chain, which unsaturated bonds are separated by at least one saturated carbon bond.
3. An emulsifying agent according to claim 1 wherein said second linking moiety comprises an ester linkage.
4. An emulsifying agent according to claim 1 wherein said first linking moiety comprises an ester, imide or amide linkage.
5. An emulsifying agent according to claim 1 wherein said emulsifying agent is of formula I:
Formula I
wherein L1 is a first lipophilic chain, L~ is a second, unsaturated lipophilic chain having an olefinic unsaturated level greater than 1, R is hydrogen or a hydrophilic group, or a direct bond to M1 when x is 0, M1 is an ester, amide or imide linkage, M~ is an ester linkage, and m is ~ 0, and x is 0 or 1.
Formula I
wherein L1 is a first lipophilic chain, L~ is a second, unsaturated lipophilic chain having an olefinic unsaturated level greater than 1, R is hydrogen or a hydrophilic group, or a direct bond to M1 when x is 0, M1 is an ester, amide or imide linkage, M~ is an ester linkage, and m is ~ 0, and x is 0 or 1.
6. An emulsifying agent as claimed in claim 5 wherein:
M1 is , when x is 0 or , M~ is and, n is ~ 1, and m ~ 0.
M1 is , when x is 0 or , M~ is and, n is ~ 1, and m ~ 0.
7. An emulsifying agent as claimed in claim 5 wherein R
is -(CH2)jOH wherein j is 1, 2 or 3, when x is 1.
is -(CH2)jOH wherein j is 1, 2 or 3, when x is 1.
8. An emulsifying agent as claimed in claim 5 wherein said emulsifying agent is of formula IA:
Formula IA
where L1, L~ and R are as defined in Claim 5, and n is ~ 1, and m ~ 0.
Formula IA
where L1, L~ and R are as defined in Claim 5, and n is ~ 1, and m ~ 0.
9. An emulsifying agent according to any one of claims 1 to 8 wherein said hydrophilic species is polar in character and comprises an organic residue having a molecular weight not exceeding 450.
10. An emulsifying agent according to claim 9 wherein the hydrophilic species comprises components selected from the group consisting of hydroxyl, aminohydroxyl, alkyl hydroxy pyridine, or polyhydroxy carboxylic acid groups.
11. An emulsifying agent according to any one of claims 1 to 8 wherein the first lipophilic chain is either monomeric or polymeric in nature, and has a chain structure incorporating a backbone sequence of at least 10 and not more than 500 linked atoms.
12. An emulsifying agent according to claim 11 wherein the first lipophilic chain is a saturated or unsaturated hydrocarbon chain derived from a polymer of a mono-olefin, and wherein the polymer chain contains from 40 to 500 carbon atoms.
13. An emulsifying agent according to any one of claims 1 to 8 wherein either said first or said second linking moieties may comprise functional groups selected from the group consisting of hydroxyl, amino or carboxylic acid groups.
14. An emulsifying agent according to claim 13 wherein the first linking moiety and the first lipophilic chain are present in the same species.
15. An emulsifying agent according to claim 14 wherein the first linking moiety and the first lipophilic moiety are present in a poly[alk(en)yl] succinic anhydride based compound or its acid form.
16. An emulsifying agent according to claim 15 wherein the first linking moiety and the first lipophilic moiety are present in the form of the residual of polyisobutylene succinic anhydride.
17. An emulsifying agent according to any one of claims 1 to 8 wherein the second lipophilic chain is derived from a polyunsaturated fatty acid.
18. An emulsifying agent according to claim 17 wherein the second lipophilic chain is linoleic acid or linolenic acid, or mixtures thereof, or rusic acid.
19. An emulsifying agent according to claim 8 wherein L1 and M1 combined are the residual of polyisobutylene succinic anhydride having a backbone structure of less than 500 carbon atoms in the polyisobutylene portion, n and m are 1, R is hydrogen or -(CH2)jOH wherein j is 1, 2 or 3, and L2 is linoleic acid or linolenic acid, or mixtures thereof, or rusic acid.
20. A process for producing an emulsion suitable for use in an emulsion explosives composition comprising emulsifying an oxygen-supplying component and a fuel to form an emulsion in which the oxygen-supplying component forms at least part of the discontinuous phase and the fuel forms at least part of the continuous phase wherein the emulsification is effected in the presence of the emulsifying agent of any one of claims 1 to 19.
21. An emulsion suitable for use in an emulsion explosive composition having a continuous water-immiscible hydrocarbon phase, a discontinuous aqueous salt or eutectic phase and at least one emulsifying agents, wherein said emulsifying agent is an emulsifying agent as claimed in any one of claims 1 to 19.
22. An emulsion according to claim 21 wherein the total emulsifier component of the emulsion comprises up to 5% by weight of the emulsion explosive composition, the discontinuous phase of the emulsion comprises 60 to 97% by weight of emulsion, and the continuous water-immiscible hydrocarbon phase of the emulsion comprises 3 to 30% by weight of the emulsion.
23. An emulsion according to claim 21 wherein the combined total level of said continuous water-immiscible hydrocarbon phase and said emulsifying agent is less than or equal to 5% by weight of the emulsion.
24. An emulsion explosive composition formed by combining the emulsion of any one of claims 21 to 23 with a self-explosive compound or with voiding agents.
25. An emulsion explosive composition according to claim 24 wherein the emulsion explosives composition comprises a discontinuous gaseous component as a voiding agent.
26. An emulsion explosive composition according to claim 24 wherein the composition is essentially oxygen balanced or not significantly oxygen deficient.
27. A method of blasting comprising placing the emulsion explosives composition of any one of claims 24 to 26 in operative contact with an initiating system including a detonator and initiating said detonator and said emulsion explosive.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002162411A CA2162411A1 (en) | 1995-11-08 | 1995-11-08 | Emulsifying agent for use in explosive compositions |
| ZA969224A ZA969224B (en) | 1995-11-08 | 1996-11-01 | Emulsifying agent for use in explosive compositions |
| MXPA/A/1996/005438A MXPA96005438A (en) | 1995-11-08 | 1996-11-07 | Emulsifying agent for use in explosi compositions |
| AU70687/96A AU7068796A (en) | 1995-11-08 | 1996-11-08 | Emulsifying agent for use in explosive compositions |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002162411A CA2162411A1 (en) | 1995-11-08 | 1995-11-08 | Emulsifying agent for use in explosive compositions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2162411A1 true CA2162411A1 (en) | 1997-05-09 |
Family
ID=4156927
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002162411A Abandoned CA2162411A1 (en) | 1995-11-08 | 1995-11-08 | Emulsifying agent for use in explosive compositions |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU7068796A (en) |
| CA (1) | CA2162411A1 (en) |
| ZA (1) | ZA969224B (en) |
-
1995
- 1995-11-08 CA CA002162411A patent/CA2162411A1/en not_active Abandoned
-
1996
- 1996-11-01 ZA ZA969224A patent/ZA969224B/en unknown
- 1996-11-08 AU AU70687/96A patent/AU7068796A/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| MX9605438A (en) | 1997-10-31 |
| AU7068796A (en) | 1997-05-15 |
| ZA969224B (en) | 1997-06-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |
Effective date: 19991108 |