CA2127302C - Low density ammonium nitrate emulsion explosive - Google Patents
Low density ammonium nitrate emulsion explosiveInfo
- Publication number
- CA2127302C CA2127302C CA002127302A CA2127302A CA2127302C CA 2127302 C CA2127302 C CA 2127302C CA 002127302 A CA002127302 A CA 002127302A CA 2127302 A CA2127302 A CA 2127302A CA 2127302 C CA2127302 C CA 2127302C
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- CA
- Canada
- Prior art keywords
- weight
- explosive
- ammonium nitrate
- emulsion
- low density
- 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.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B31/00—Compositions containing an inorganic nitrogen-oxygen salt
- C06B31/28—Compositions containing an inorganic nitrogen-oxygen salt the salt being ammonium nitrate
- C06B31/30—Compositions containing an inorganic nitrogen-oxygen salt the salt being ammonium nitrate with vegetable matter; with resin; with rubber
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Liquid Carbonaceous Fuels (AREA)
Abstract
A low density explosive is provided which is comprised of a mixture of particles of an oxidizer salt, such as ammonium nitrate prills, an emulsion explosive matrix, and particles of a low density material such as perlite or foamed polystyrene. The explosives of the present invention provide a lower density material than comparable ANFO or Heavy ANFO type explosives.
Description
Low Density Ammonium Nitrate Emulsion Explosive Field of the Invention This invention relates to the explosives art, and in particular, to the production and use of low density ammonium nitrate-emulsion type explosives.
Description of the Related Art Various explosive products, such as ANFO (ammonium nitrate-fuel oil), are widely used in the explosives industry as a readily available and relatively inexpensive bulk explosive, and generally comprise a mixture of about 95% (by weight) porous ammonium nitrate prills with about 5% (by weight) of a generally liquid, or liquefiable, hydrocarbon, such as fuel oil. Other oxidizing salts, such as sodium nitrate, calcium nitrate and the like may be substituted for a portion of the ammonium nitrate, and various fuel oils, waxes and the like may be used for the hydrocarbon component.
In order to modify the handling or performance properties of an ANFO explosive, and/or to provide water resistance to ANFO explosives, it is common in the explosives art to combine ANFO with other materials, such as, for example, an emulsion explosive to produce an explosive termed in the industry as Heavy ANFO. Heavy ANFO is normally used to produce explosives having a higher loading density than is possible using poured ANFO
alone.
Similarly, ammonium nitrate prills can also be combined with an emulsion explosive to create a doped emulsion. The doped emulsion provides a method for modifying the explosive properties of an emulsion alone.
In order to further control the handling and performance properties of these types of materials, the explosives industry is constantly searching for different B
means to control density and product performance for Ammonium Nitrate (AN)-containing explosive materials.
Summary of the Invention Accordingly, the present invention provides an S explosive composition comprising: i) an oxidizer salt such as ammonium nitrate, optionally in combination with a fuel oil suitable for producing an ANFO type explosive;
ii) an emulsion explosive matrix; and iii) sufficient low density material to lower the density of the explosive, wherein said ammonium nitrate prills are uncoated or have been pre-coated with up to 2% of a fuel phase by weight of the formulation.
The low density material is preferably a solid low density material such as foamed perlite, or a foamed polymeric material such as foamed polystyrene.
Preferably, the level of the low density material is less than 50%, by weight, of the total formulation, and more preferably, is between l and 30%, by weight. More preferably still, the level of low density material is between 3 and 15% and even more preferably, between 3 and 7% by weight of the total formulation.
The fuel oil (when present) utilized in the preparation of the ANFO may be any of the liquid or liquefiable hydrocarbons generally used in this art. The amount of fuel oil may, however, vary from standard ANFO
formulation levels in order to adjust the oxygen balance of the total explosive composition. The level of fuel oil, when added, is preferably less than 10%, and more preferably is between l to 6%, by weight of ammonium nitrate and fuel oil.
The oxidizer salt may, however, be added to the formulation as a dry particle, preferably in the form of prills. Most preferably, the oxidizer salt is ammonium nitrate (AN) in prill form, and in particular, is a porous, explosives-grade ammonium nitrate (EGAN) prill.
However, a portion of the ammonium nitrate might also be replaced by other oxidizing salts known in the industry, such as sodium nitrate, calcium nitrate and the like. The level of AN prills in the final explosive composition is preferably up to 90% by weight. More preferably, the level of AN is between 60 to 90%, and most preferably between 70 to 90% by weight.
The emulsion explosive may be any of the emulsion explosives known in the industry and generally comprises a discontinuous phase of an oxidizer salt which has been emulsified into a continuous fuel phase. The level of emulsion explosive may vary depending on the desired properties of the final composition, but is preferably between 3 and 60% by weight of the total composition, and more preferably, is between 3 and 25%, by weight. More preferable still, the emulsion explosive comprises between 5 and 20% by weight, and most preferably, the composition comprises between 5 to 12% emulsion explosive, by weight. While the emulsion explosive acts as a low density blasting agent, it also acts as a binding agent to aid in through mixing of the AN prills and the low density material.
The oxidizer salt for use in the discontinuous phase of the emulsion is preferably selected from the group consisting of alkali and alkaline earth metal nitrates, chlorates and perchlorates, ammonium nitrate, ammonium chlorates, ammonium perchlorate and mixtures thereof. It is particularly preferred that the oxidizer salt is ammonium nitrate, or a mixture of ammonium and sodium nitrate. A preferred oxidizer salt mixture comprises a solution of 77% ammonium nitrate, 11% sodium nitrate and 12% water, by weight.
The oxidizer salt in the emulsion is typically a concentrated aqueous solution of the salt or mixture of salts. However, the oxidizer salt may also be a liquefied, melted solution of'the oxidizer salt where a lower water content is desired. It is particularly D
preferred that the discontinuous phase of the emulsion explosive be a eutectic composition. By eutectic composition it is meant that the melting point of the composition is either at the eutectic or in the region of the eutectic or the components of the composition.
The oxidizer salt for use in the discontinuous phase of the emulsion may further comprise a melting point depressant. Suitable melting point depressants for use with ammonium nitrate in the discontinuous phase include inorganic salts such as lithium nitrate, silver nitrate, lead 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, 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 organic fuel phase of the emulsion explosive comprises an organic fuel.
Suitable 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, (eg. microcrystalline wax, paraffin wax and slack wax), paraffin oils, benzene, toluene, xylenes, asphaltic materials, polymeric oils '.
'.
Description of the Related Art Various explosive products, such as ANFO (ammonium nitrate-fuel oil), are widely used in the explosives industry as a readily available and relatively inexpensive bulk explosive, and generally comprise a mixture of about 95% (by weight) porous ammonium nitrate prills with about 5% (by weight) of a generally liquid, or liquefiable, hydrocarbon, such as fuel oil. Other oxidizing salts, such as sodium nitrate, calcium nitrate and the like may be substituted for a portion of the ammonium nitrate, and various fuel oils, waxes and the like may be used for the hydrocarbon component.
In order to modify the handling or performance properties of an ANFO explosive, and/or to provide water resistance to ANFO explosives, it is common in the explosives art to combine ANFO with other materials, such as, for example, an emulsion explosive to produce an explosive termed in the industry as Heavy ANFO. Heavy ANFO is normally used to produce explosives having a higher loading density than is possible using poured ANFO
alone.
Similarly, ammonium nitrate prills can also be combined with an emulsion explosive to create a doped emulsion. The doped emulsion provides a method for modifying the explosive properties of an emulsion alone.
In order to further control the handling and performance properties of these types of materials, the explosives industry is constantly searching for different B
means to control density and product performance for Ammonium Nitrate (AN)-containing explosive materials.
Summary of the Invention Accordingly, the present invention provides an S explosive composition comprising: i) an oxidizer salt such as ammonium nitrate, optionally in combination with a fuel oil suitable for producing an ANFO type explosive;
ii) an emulsion explosive matrix; and iii) sufficient low density material to lower the density of the explosive, wherein said ammonium nitrate prills are uncoated or have been pre-coated with up to 2% of a fuel phase by weight of the formulation.
The low density material is preferably a solid low density material such as foamed perlite, or a foamed polymeric material such as foamed polystyrene.
Preferably, the level of the low density material is less than 50%, by weight, of the total formulation, and more preferably, is between l and 30%, by weight. More preferably still, the level of low density material is between 3 and 15% and even more preferably, between 3 and 7% by weight of the total formulation.
The fuel oil (when present) utilized in the preparation of the ANFO may be any of the liquid or liquefiable hydrocarbons generally used in this art. The amount of fuel oil may, however, vary from standard ANFO
formulation levels in order to adjust the oxygen balance of the total explosive composition. The level of fuel oil, when added, is preferably less than 10%, and more preferably is between l to 6%, by weight of ammonium nitrate and fuel oil.
The oxidizer salt may, however, be added to the formulation as a dry particle, preferably in the form of prills. Most preferably, the oxidizer salt is ammonium nitrate (AN) in prill form, and in particular, is a porous, explosives-grade ammonium nitrate (EGAN) prill.
However, a portion of the ammonium nitrate might also be replaced by other oxidizing salts known in the industry, such as sodium nitrate, calcium nitrate and the like. The level of AN prills in the final explosive composition is preferably up to 90% by weight. More preferably, the level of AN is between 60 to 90%, and most preferably between 70 to 90% by weight.
The emulsion explosive may be any of the emulsion explosives known in the industry and generally comprises a discontinuous phase of an oxidizer salt which has been emulsified into a continuous fuel phase. The level of emulsion explosive may vary depending on the desired properties of the final composition, but is preferably between 3 and 60% by weight of the total composition, and more preferably, is between 3 and 25%, by weight. More preferable still, the emulsion explosive comprises between 5 and 20% by weight, and most preferably, the composition comprises between 5 to 12% emulsion explosive, by weight. While the emulsion explosive acts as a low density blasting agent, it also acts as a binding agent to aid in through mixing of the AN prills and the low density material.
The oxidizer salt for use in the discontinuous phase of the emulsion is preferably selected from the group consisting of alkali and alkaline earth metal nitrates, chlorates and perchlorates, ammonium nitrate, ammonium chlorates, ammonium perchlorate and mixtures thereof. It is particularly preferred that the oxidizer salt is ammonium nitrate, or a mixture of ammonium and sodium nitrate. A preferred oxidizer salt mixture comprises a solution of 77% ammonium nitrate, 11% sodium nitrate and 12% water, by weight.
The oxidizer salt in the emulsion is typically a concentrated aqueous solution of the salt or mixture of salts. However, the oxidizer salt may also be a liquefied, melted solution of'the oxidizer salt where a lower water content is desired. It is particularly D
preferred that the discontinuous phase of the emulsion explosive be a eutectic composition. By eutectic composition it is meant that the melting point of the composition is either at the eutectic or in the region of the eutectic or the components of the composition.
The oxidizer salt for use in the discontinuous phase of the emulsion may further comprise a melting point depressant. Suitable melting point depressants for use with ammonium nitrate in the discontinuous phase include inorganic salts such as lithium nitrate, silver nitrate, lead 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, 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 organic fuel phase of the emulsion explosive comprises an organic fuel.
Suitable 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, (eg. 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, 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. More preferably the organic fuel is paraffin oil.
Typically, the continuous water-immiscible organic fuel phase of the emulsion explosive comprises 3 to 30%
by weight of the emulsion explosive, and preferably 5 to 15% by weight of the emulsion explosive. This level of the fuel phase may be in excess of the amount generally used for emulsion explosives only, but may be present in order to provide fuel for absorption into the AN prills, where necessary to produce ANFO.
The emulsion explosive also comprises an emulsifier component to aid in the formation to the emulsion, and to improve the stability of the emulsion. The emulsifier component may be chosen from the wide range of emulsifying agents known in the art to be suitable for the preparation of emulsion explosive compositions.
Examples of such emulsifying agents include alcohol alkoxylates, phenol alkoxylates, poly(oxyalkylene) glycols, poly(oxyalkylene) fatty acid esters, amine alkoxylates, fatty acid esters of sorbitol and glycerol, fatty acid salts, sorbitan esters, poly(oxyalkylene) sorbitan esters, fatty amine alkoxylates, poly(oxyalkylene)glycol esters, fatty acid amides, fatty acid amide alkoxylates, fatty amine, quaternary amines, alkyloxazolines, alkenyloxazolines, imidazolines, alkyl-sulfonates, alkylarylsulfonates, alkylsulfosuccinates, alkylphosphates, alkenylphosphates, phosphate esters, lecithin, copolymers of poly(oxyalkylene) glycols and poly(12-hydroxystearic acid), condensation products of compounds comprising at least one primary amine and poly[alk(en)yl]succinic acid or anhydride, and mixtures thereof.
'O
p Among the preferred emulsifying agents are the 2-alkyl- and 2-alkenyl-4,4'-bis(hydroxymethyl)oxazolines, the fatty acid esters of sorbitol, lecithin, copolymers of poly(oxyalkylene)glycols and poly(12-hydroxystearic acid), condensation products of compounds comprising at least one primary amine and poly[alk(en)yl]succinic acid or anhydride, and mixtures thereof.
More preferably the emulsifier component comprises a condensation product of a compound comprising at least one primary amine and a poly[alk(en)yl]succinic acid or anhydride. A preferred emulsifier is a polyisobutylene succinic anhydride (PIBSA) based surfactant, which surfactants are described in Canadian Patent No.
1,244,463 (Baker). U.S. Patent No. 4,822,433 (Cooper and Baker) discloses emulsion explosive compositions in which the emulsifier is a condensation product of a poly[alk(en)yl]succinic anhydride and an amine such as ethylene diamine, diethylene triamine and ethanolamine.
Further examples of preferred condensation products may be found in European Patent Publication No. 0,331,306 (published September 9, 1989) and U.S. Patent No.
4,999,062.
Typically, the emulsifier component of the emulsion explosive comprises up to 5% by weight of the emulsion explosive composition. Higher proportions 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 is in the range of from 0.4 to 3.0~ by weight of the emulsion explosive.
If desired, other optional fuel materials, hereinafter referred to as secondary fuels, may be incorporated into the emulsion explosives. Examples of such secondary fuels include finely divided solids. Examples of solid secondary fuels include finely divided materials such as:
sulfuri aluminum; 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 vegetable products such as starch, nut meal, grain meal and wood pulp; and mixtures thereof.
Typically, the optional secondary fuel component of the emulsion explosive comprises from 0 to 30% by weight of the emulsion explosive.
The emulsion portion, or more generally, the complete explosive composition is preferably oxygen balanced. This may be achieved by providing a blend of components which are themselves oxygen balanced or by providing a blend which, while having a net oxygen balance, comprises components which are not themselves oxygen balanced. This provides a more efficient explosive composition which, when detonated, leaves fewer unreacted components.
Additional components may be added to the explosive composition to control the oxygen balance of the explosive composition.
The emulsion explosive component may additionally comprise a discontinuous gaseous component which gaseous component can be utilized to vary the density and/or the sensitivity of the explosive composition.
The methods of incorporating a gaseous component and the enhanced sensitivity of emulsion explosives comprising gaseous components are well known to those skilled in the art. The gaseous components may, for example, be incorporated into the emulsion explosive as fine gas bubbles dispersed through the composition, as hollow particles which are often referred to as microballoons or as microspheres, as porous particles, or mixtures thereof.
B~
ICICAN 808 2 ~ 2~302 A discontinuous phase of fine gas bubbles may be incorporated into the emulsion explosive by mechanical agitation, injection or bubbling the gas through the emulsion, or by chemical generation of the gas ln situ.
Suitable chemicals for the ln situ generation of gas bubbles include peroxides, such as hydrogen peroxide, nitrates, such as sodium nitrate, nitrosoamines, such as N,N'-dinitrosopentamethylenetetramine, alkali metal borohydrides, such as sodium borohydride, and carbonates, such as sodium carbonate. Preferred chemical for the in situ generation of gas bubbles are nitrous acid and its salts which decompose under conditions of acid pH to produce gas bubbles. Preferred nitrous acid salts include alkali metal nitrites, such as sodium nitrite. Catalytic agents such as thiocyanate or thiourea may be used to accelerate the decomposition of a nitrite gassing agent.
Suitable small hollow particles for use in the emulsion explosive, or as the low density material, 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.
In a preferred embodiment, the explosive compositions of the present invention are formulated using polystyrene, and preferably, polystyrene which has been overexpanded in order to have a bulk density of less than 0.04 g/cc. When polystyrene is utilized, it is particularly desirable that any fuel oil added to the ammonium nitrate prills, or used in the production of the emulsion, be compatible with the polystyrene, and not dissolve the structure of the polystyrene material. For this application, it is preferable that the explosive composition be free of fuel oil added to the ammonium nitrate, and that the emulsion explosive be based on a vegetable oil, as is described in U.S. Patent No.
5,322,576 issued June 21, 1994. Accordingly, in a B
preferred embodiment, the present invention provides an explosive composition comprising:i) 70 to 90% by weight, of ammonium nitrate prills; ii) 5 to 20% by weight of an emulsion explosive matrix, wherein said emulsion S explosive matrix comprises vegetable oil as the continuous fuel phase of the emulsion; and iii) 3 to 15%
by weight of a low density material, which is preferably foamed polystyrene having a bulk density of less than 0.0~ g/cc, in order to lower the density of the explosive.
In a further aspect, the present invention also provides a method for the production of an explosive comprising mixing of solid particles of an oxidizer salt, such as porous prills of ammonium nitrate which have been optionally treated with a fuel oil to produce an ANFO
type material, an emulsion explosive which optionally contains excess fuel oil, and a low density material such as perlite and/or foamed polystyrene.
Examples The invention will now be demonstrated, by way of example only, by reference to the following examples.
A series of explosive compositions made in accordance with the present invention were prepared by mixing together an emulsion explosive, ammonium nitrate, and a low density material as indicated. The properties of the resultant explosive were measured, and are presented in Table 1.
~.' Table 1 Test No. 1 2 3 Formulation % (by weight): 83 75 84 AN prills Fuel Oil 2 5 0 Emulsion Expl (a) 10 10 10 Polystyrene 5 - 6 Perlite - 10 Density of AN or ANFO/emulsion0.88 0.9 0.88 mix onl~ (g/cc) Density with Perlite or 0.5 0.6 0.4 Polystyrene (g/cc) Velocity of Detonation (VOD) in m/sec:
0.65cm cartridge - - 2500 15cm cartridge 2,083 1,644 15cm 1,995 Fail 13cm 1,875 (a) - Emulsion explosive comprising:
Examples 1 & 2 - A 70/15/15 mixture by weight of AN/SN/water as aqueous phase, mixed in a weight ratio of 93.5 to 6.5 with a mixture of isopar oil and sorbitan monooleate.
Example 3 - A 69/15/16 mixture by weight of AN/SN/water as aqueous phase, mixed in a weight ratio of 91 to 9 with a mixture of vegetable oil (corn oil) and a PIBSA-based surfactant.
The results shown in Table 1 demonstrate that usable explosive compositions can be prepared having reduced densities over prior art formulations.
Having described specific embodiments of the present S 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.
Typically, the continuous water-immiscible organic fuel phase of the emulsion explosive comprises 3 to 30%
by weight of the emulsion explosive, and preferably 5 to 15% by weight of the emulsion explosive. This level of the fuel phase may be in excess of the amount generally used for emulsion explosives only, but may be present in order to provide fuel for absorption into the AN prills, where necessary to produce ANFO.
The emulsion explosive also comprises an emulsifier component to aid in the formation to the emulsion, and to improve the stability of the emulsion. The emulsifier component may be chosen from the wide range of emulsifying agents known in the art to be suitable for the preparation of emulsion explosive compositions.
Examples of such emulsifying agents include alcohol alkoxylates, phenol alkoxylates, poly(oxyalkylene) glycols, poly(oxyalkylene) fatty acid esters, amine alkoxylates, fatty acid esters of sorbitol and glycerol, fatty acid salts, sorbitan esters, poly(oxyalkylene) sorbitan esters, fatty amine alkoxylates, poly(oxyalkylene)glycol esters, fatty acid amides, fatty acid amide alkoxylates, fatty amine, quaternary amines, alkyloxazolines, alkenyloxazolines, imidazolines, alkyl-sulfonates, alkylarylsulfonates, alkylsulfosuccinates, alkylphosphates, alkenylphosphates, phosphate esters, lecithin, copolymers of poly(oxyalkylene) glycols and poly(12-hydroxystearic acid), condensation products of compounds comprising at least one primary amine and poly[alk(en)yl]succinic acid or anhydride, and mixtures thereof.
'O
p Among the preferred emulsifying agents are the 2-alkyl- and 2-alkenyl-4,4'-bis(hydroxymethyl)oxazolines, the fatty acid esters of sorbitol, lecithin, copolymers of poly(oxyalkylene)glycols and poly(12-hydroxystearic acid), condensation products of compounds comprising at least one primary amine and poly[alk(en)yl]succinic acid or anhydride, and mixtures thereof.
More preferably the emulsifier component comprises a condensation product of a compound comprising at least one primary amine and a poly[alk(en)yl]succinic acid or anhydride. A preferred emulsifier is a polyisobutylene succinic anhydride (PIBSA) based surfactant, which surfactants are described in Canadian Patent No.
1,244,463 (Baker). U.S. Patent No. 4,822,433 (Cooper and Baker) discloses emulsion explosive compositions in which the emulsifier is a condensation product of a poly[alk(en)yl]succinic anhydride and an amine such as ethylene diamine, diethylene triamine and ethanolamine.
Further examples of preferred condensation products may be found in European Patent Publication No. 0,331,306 (published September 9, 1989) and U.S. Patent No.
4,999,062.
Typically, the emulsifier component of the emulsion explosive comprises up to 5% by weight of the emulsion explosive composition. Higher proportions 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 is in the range of from 0.4 to 3.0~ by weight of the emulsion explosive.
If desired, other optional fuel materials, hereinafter referred to as secondary fuels, may be incorporated into the emulsion explosives. Examples of such secondary fuels include finely divided solids. Examples of solid secondary fuels include finely divided materials such as:
sulfuri aluminum; 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 vegetable products such as starch, nut meal, grain meal and wood pulp; and mixtures thereof.
Typically, the optional secondary fuel component of the emulsion explosive comprises from 0 to 30% by weight of the emulsion explosive.
The emulsion portion, or more generally, the complete explosive composition is preferably oxygen balanced. This may be achieved by providing a blend of components which are themselves oxygen balanced or by providing a blend which, while having a net oxygen balance, comprises components which are not themselves oxygen balanced. This provides a more efficient explosive composition which, when detonated, leaves fewer unreacted components.
Additional components may be added to the explosive composition to control the oxygen balance of the explosive composition.
The emulsion explosive component may additionally comprise a discontinuous gaseous component which gaseous component can be utilized to vary the density and/or the sensitivity of the explosive composition.
The methods of incorporating a gaseous component and the enhanced sensitivity of emulsion explosives comprising gaseous components are well known to those skilled in the art. The gaseous components may, for example, be incorporated into the emulsion explosive as fine gas bubbles dispersed through the composition, as hollow particles which are often referred to as microballoons or as microspheres, as porous particles, or mixtures thereof.
B~
ICICAN 808 2 ~ 2~302 A discontinuous phase of fine gas bubbles may be incorporated into the emulsion explosive by mechanical agitation, injection or bubbling the gas through the emulsion, or by chemical generation of the gas ln situ.
Suitable chemicals for the ln situ generation of gas bubbles include peroxides, such as hydrogen peroxide, nitrates, such as sodium nitrate, nitrosoamines, such as N,N'-dinitrosopentamethylenetetramine, alkali metal borohydrides, such as sodium borohydride, and carbonates, such as sodium carbonate. Preferred chemical for the in situ generation of gas bubbles are nitrous acid and its salts which decompose under conditions of acid pH to produce gas bubbles. Preferred nitrous acid salts include alkali metal nitrites, such as sodium nitrite. Catalytic agents such as thiocyanate or thiourea may be used to accelerate the decomposition of a nitrite gassing agent.
Suitable small hollow particles for use in the emulsion explosive, or as the low density material, 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.
In a preferred embodiment, the explosive compositions of the present invention are formulated using polystyrene, and preferably, polystyrene which has been overexpanded in order to have a bulk density of less than 0.04 g/cc. When polystyrene is utilized, it is particularly desirable that any fuel oil added to the ammonium nitrate prills, or used in the production of the emulsion, be compatible with the polystyrene, and not dissolve the structure of the polystyrene material. For this application, it is preferable that the explosive composition be free of fuel oil added to the ammonium nitrate, and that the emulsion explosive be based on a vegetable oil, as is described in U.S. Patent No.
5,322,576 issued June 21, 1994. Accordingly, in a B
preferred embodiment, the present invention provides an explosive composition comprising:i) 70 to 90% by weight, of ammonium nitrate prills; ii) 5 to 20% by weight of an emulsion explosive matrix, wherein said emulsion S explosive matrix comprises vegetable oil as the continuous fuel phase of the emulsion; and iii) 3 to 15%
by weight of a low density material, which is preferably foamed polystyrene having a bulk density of less than 0.0~ g/cc, in order to lower the density of the explosive.
In a further aspect, the present invention also provides a method for the production of an explosive comprising mixing of solid particles of an oxidizer salt, such as porous prills of ammonium nitrate which have been optionally treated with a fuel oil to produce an ANFO
type material, an emulsion explosive which optionally contains excess fuel oil, and a low density material such as perlite and/or foamed polystyrene.
Examples The invention will now be demonstrated, by way of example only, by reference to the following examples.
A series of explosive compositions made in accordance with the present invention were prepared by mixing together an emulsion explosive, ammonium nitrate, and a low density material as indicated. The properties of the resultant explosive were measured, and are presented in Table 1.
~.' Table 1 Test No. 1 2 3 Formulation % (by weight): 83 75 84 AN prills Fuel Oil 2 5 0 Emulsion Expl (a) 10 10 10 Polystyrene 5 - 6 Perlite - 10 Density of AN or ANFO/emulsion0.88 0.9 0.88 mix onl~ (g/cc) Density with Perlite or 0.5 0.6 0.4 Polystyrene (g/cc) Velocity of Detonation (VOD) in m/sec:
0.65cm cartridge - - 2500 15cm cartridge 2,083 1,644 15cm 1,995 Fail 13cm 1,875 (a) - Emulsion explosive comprising:
Examples 1 & 2 - A 70/15/15 mixture by weight of AN/SN/water as aqueous phase, mixed in a weight ratio of 93.5 to 6.5 with a mixture of isopar oil and sorbitan monooleate.
Example 3 - A 69/15/16 mixture by weight of AN/SN/water as aqueous phase, mixed in a weight ratio of 91 to 9 with a mixture of vegetable oil (corn oil) and a PIBSA-based surfactant.
The results shown in Table 1 demonstrate that usable explosive compositions can be prepared having reduced densities over prior art formulations.
Having described specific embodiments of the present S 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 (8)
1. An explosive composition comprising: i) 70 to 90%
by weight, of ammonium nitrate prills; ii) 5 to 20% by weight of an emulsion explosive matrix; and iii) 3 to 15%
by weight of a low density material to lower the density of the explosive, wherein said ammonium nitrate prills are uncoated or have been pre-coated with up to 2% of a fuel phase by weight of the formulation.
by weight, of ammonium nitrate prills; ii) 5 to 20% by weight of an emulsion explosive matrix; and iii) 3 to 15%
by weight of a low density material to lower the density of the explosive, wherein said ammonium nitrate prills are uncoated or have been pre-coated with up to 2% of a fuel phase by weight of the formulation.
2. An explosive composition as claimed in Claim 1 wherein said low density material is foamed perlite or foamed polystyrene.
3. An explosive composition as claimed in any one of Claims 1 or 2 wherein said emulsion explosive comprises a discontinuous oxidizer salt phase, a continuous fuel phase, and a PIBSA-based surfactant as an emulsifier.
4. An explosive composition as claimed in Claim 3 wherein said fuel phase comprises a vegetable oil.
5. An explosive composition comprising: i) 70 to 90%
by weight, of ammonium nitrate prills; ii) 5 to 20% by weight of an emulsion explosive matrix, wherein said emulsion explosive matrix comprises vegetable oil as the continuous fuel phase of the emulsion; and iii) 3 to 15%
by weight of a low density material, wherein said ammonium nitrate prills are uncoated or have been pre-coated with up to 2% of a fuel phase by weight of the total formulation.
by weight, of ammonium nitrate prills; ii) 5 to 20% by weight of an emulsion explosive matrix, wherein said emulsion explosive matrix comprises vegetable oil as the continuous fuel phase of the emulsion; and iii) 3 to 15%
by weight of a low density material, wherein said ammonium nitrate prills are uncoated or have been pre-coated with up to 2% of a fuel phase by weight of the total formulation.
6. An explosive composition as claimed in Claim 5 wherein said low density material is foamed polystyrene having a bulk density of less than 0.04 g/cc.
7. An explosive composition as claimed in Claim 1 or Claim 2 wherein said ammonium nitrate prills have been pre-coated with 1 to 6% fuel oil (by weight of AN and fuel oil).
8. A method for preparing an explosive composition comprising mixing 70 to 90% by weight of ammonium nitrate prills, 5 to 12% by weight of an emulsion explosive matrix, and 3 to 7% by weight of a low density material;
wherein said ammonium nitrate prills are uncoated or have been pre-coated with up to 2% of a fuel phase by weight of the total formulation.
wherein said ammonium nitrate prills are uncoated or have been pre-coated with up to 2% of a fuel phase by weight of the total formulation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002127302A CA2127302C (en) | 1994-07-04 | 1994-07-04 | Low density ammonium nitrate emulsion explosive |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002127302A CA2127302C (en) | 1994-07-04 | 1994-07-04 | Low density ammonium nitrate emulsion explosive |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2127302A1 CA2127302A1 (en) | 1996-01-05 |
| CA2127302C true CA2127302C (en) | 1998-07-14 |
Family
ID=4153944
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002127302A Expired - Fee Related CA2127302C (en) | 1994-07-04 | 1994-07-04 | Low density ammonium nitrate emulsion explosive |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2127302C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8696837B2 (en) | 2005-10-10 | 2014-04-15 | Kevin H. Waldock | Heavy ANFO and a tailored expanded polymeric density control agent |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CL2009000278A1 (en) * | 2009-02-06 | 2011-01-21 | Enaex Servicios S A | Low density granular blasting agent consisting of expanded perlite with particle size range between 0.5 and 15 mm and with density between 0.05 and 0.35 g / cm3, ammonium nitrate crystals in pores and surface area the perlite and liquid fuel type was oil; preparation process, intermediate compound; and use. |
| WO2013102364A1 (en) * | 2012-01-05 | 2013-07-11 | Xue Shizhong | Preparation method for different density explosives and different density explosives |
| US10138720B2 (en) | 2017-03-17 | 2018-11-27 | Energy Technology Group | Method and system for perforating and fragmenting sediments using blasting material |
-
1994
- 1994-07-04 CA CA002127302A patent/CA2127302C/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8696837B2 (en) | 2005-10-10 | 2014-04-15 | Kevin H. Waldock | Heavy ANFO and a tailored expanded polymeric density control agent |
| US9290418B2 (en) | 2005-10-10 | 2016-03-22 | Lde Corporation | Heavy ANFO and a tailored expanded polymeric density control agent |
| US9611184B2 (en) | 2005-10-10 | 2017-04-04 | Lde Corporation | Heavy ANFO and a tailored expanded polymeric density control agent |
| US10202315B2 (en) | 2005-10-10 | 2019-02-12 | Lde Corporation | Heavy ANFO and a tailored expanded polymeric density control agent |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2127302A1 (en) | 1996-01-05 |
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