CA1330397C - Emulsion explosive containing particulate insoluble bentonite - Google Patents
Emulsion explosive containing particulate insoluble bentoniteInfo
- Publication number
- CA1330397C CA1330397C CA000568451A CA568451A CA1330397C CA 1330397 C CA1330397 C CA 1330397C CA 000568451 A CA000568451 A CA 000568451A CA 568451 A CA568451 A CA 568451A CA 1330397 C CA1330397 C CA 1330397C
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- CA
- Canada
- Prior art keywords
- emulsion
- bentonite
- fuel
- group
- mass
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
- C06B23/001—Fillers, gelling and thickening agents (e.g. fibres), absorbents for nitroglycerine
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Colloid Chemistry (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
- Medicinal Preparation (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
Abstract
ABSTRACT
"Emulsion Explosive Containing Particulate Insoluble Bentonite"
In the manufacture of an emulsion explosive comprising a discontinuous phase which forms an oxidizing salt-containing component and a continuous phase which is immiscible with the discontinuous phase and which forms a fuel component, a method of thickening or increasing the viscosity of the emulsion which comprises dispersing insoluble particulate bentonite in at least one of the components of the emulsion.
"Emulsion Explosive Containing Particulate Insoluble Bentonite"
In the manufacture of an emulsion explosive comprising a discontinuous phase which forms an oxidizing salt-containing component and a continuous phase which is immiscible with the discontinuous phase and which forms a fuel component, a method of thickening or increasing the viscosity of the emulsion which comprises dispersing insoluble particulate bentonite in at least one of the components of the emulsion.
Description
~33~7 ~ -"Emulsion Explosive ContaLning Particulate Insoluble Bentonite" ~
. ~
THIS INVENTION relates to an explosive. lt relates in particular to the manufacture of an emulsion explosive comprising a discontinuous phase which forms an oxidizing salt-containing component and a continuous 5 phase which is immiscible with the discontinuous phase and which forms a fuel component.
'""''':
Such explosives, when the oxidizing salt-containing component contains water and is in the form of an aqueous solution, are known as 'water-in-fuel' emulsions, and when Ihe oxidizirg salt component 10 contains little or no water, they can be regarded as 'm;it-in-fuel' emulsions.
' .;
According to the invention, in the manufacture of an emulsion explosive `~
comprising a discontinuous phase which for2s an oxidizing salt-containing component and a continuous phase ~ich is immiscible ;
15 witll the discontinuous phase and which forms a fuel component, there is 5 provided a method of thickening or increasing the viscosity of the emulsion which comprises dispersing insoluble parti~ulate benton]te in ;
at least o~e of the components of the emulsion.
The bentonite may be added to the emulsion formed after admixture of 20 s~id components, in a proportion o~ from about 1,0 tc about 5,0% by mass ` -~
- ~33~ J
based on the emulsion mass. The Applicant has found that the bentonite is thereby dispersed through the emulsion withou~ dissolving in eit~er of ~he c~nponents, and without causing crystallization.
The bentonite may be swellable sodium bentoni~e which is composed largely of the mineral montmorillonite. It may be of the so-called USA
tight-spec type having a degree of dry particle fineness as follows:
90% by mass minimu~ finer than US Sieve No. 40 and 10% by mass maximum finer than US Sieve No 200. In other words, at least 90~ by mass of the bentonite particles may have a particle size less than 425 microns and 15 at the most 10% by mass of the bentoni~e Farticles may have a particle size less than 75 microns. The average particle size of the bentonite particles may be from about î5 microns to about 425 microns, preferably from about 75 microns to abou-t 350 microns.
The sodium bentonite may be that which is commercially aYailable in powder form under the trade name h~-80*VOLCLAY h~STERN BENTONITE-l~T
from The AmeTican Colloid Company, and which has a water content of between 5 and 10~ by mass, a dry particle fineness of 10% by mass maximum retained on US Sieve No. 40 and 10% by mass maximum passing US
Sieve No. 200, and a wet particle ~ineness of at least 94% by mass being finer than US Sieve No. 20~ and at least 92% by mass being finer than US
Sieve No. 325.
The bentonite may be dispersed in the emulsion by admixture of the powder with the emulsion in a low shear blender.
.
The discontinuous phase may comprise at least one oxidizing salt ; 30 selected from the group cons;sting of ammonium nitrate, al~ali me~al f * Trade Mark :; .
. -3-~3~
nitTates, alkaline earth metal nitrates, ammonium perchlora~e, alkali metal perchlorates, and alkaline earth metal perchlora~es.
The discontinuous phase may comprise ammonium nitrate with at least one further compound selected from the group consisting of oxygen-releasing salts and fuels which, together with the ammonium nitrate, forms a melt which has a melting point which is lower than that of the ammonium nitrate. Said further compound may be sodium nitrate, calcium nitrate, urea, urea derivati~es such as thiourea, or the like. The discontinuous phase may in certain cases comprise water, which is kept to a minimum to avoid wasted energy arising from steam generation, but which is employed to facilitate melting/dissolving of the oxidi~ing salt component to avoid excessive high processing temperatures during formation of the base emulsion.
The fuel component of the emulsion may fonn from 2 tO 25% by mass of the emulsion, preferably about 3 to 12% by mass.
The fuel of the fuel component will be immiscible with and insoluble in water. Preferably, the fuel of the fuel component is non-self-explosive and is selected from at least one member of the group consisting of hydrocarbons, halogenated hydrocarbons and nitrated hydrocarbons.
Typically, said fuel comprises at least one wax selected from the group consisting of paraffin waxes, microcrystalline waxes and slack waxes, and it may comprise at least one member of the group consisting of mineral oils, fuel oils, lubricating oils, liquid paraffin, xylene, toluene, petrolatum and dinitrotoluene.
~33~7 The fuel may comprise an emulsifier or a mixture of suitable emulsifiers. The fuel component may thus comprise at least one elnulsifier selected from the group consisting of sorbitan sesquioleate, sorbitan monooleate, sorbitan monopalmitate~ sodium monostearate, sodium tristearate, the mono- and diglycerides of ~at-forming fatty acids, soya bean lecithin, derivatives of lanolin, alkyl benzene sulphonates, oleyl acid phosphate, laurylamine acetate, decaglycerol decaoleate, decaglycerol decastearate, 2-oleyl-4,4'-bis(hydroxymethyl~-2-oxazoline, polymeric emulsifiers containing polyethylene glycol backbones with fatty acid side chains and derivatives of polyisobutylene succinic anhydride.
The emulsifiers act as surfactants and stabilizers to promote the - formation of the emulsion and to resist crystallization and/or coalescence of the discontinuous phase.
The method may include the step of dispersing a density-reducing agent in the emulsion to form an emulsion having a densi~y of from 1,10 to 1,15 g/cm3 at 25C.
The density-reducing agent may be selected from the group consisting of microballoons, microspheres and gas bubbles. ln one embodiment, the eventual emulsion may thus include glass microballoons, microspheres of polymeric material or another form of density-reducing agent, to provide the emulsion with the final density of 1,10 to 1,15 g/cm3 at 25C. The emulsion may then comprise up to about 1~% by mass of glass microballoons (eg C15/250*glass microballoons available from 3M South Africa (Pty) Limited) or microspheres of a polymeric materi~l (eg EXPANCEL 642 DE*microspheres available from KemaNord AB, Sweden) 9 which ,~ * Trade Mark .
~3~3~
can further act to sensitize the explosive. Al~hough the mass of microballoons or microspheres included may be up to 10%, it is preferably less than 4,5~ by mass, based on the mass of the emulsion to which they are added. In anot~ler embodiment, the density-reducing agent may comprise air bubbles in the emulsion. The bubbles can then be mechanically induced eg by physical mixing or blowing, and/or chemically induced, eg by a chemical ~oaming agent such as sodium nitrite added to the emulsion.
, The inYention extellds to an emulsion explosive whenever m~nufactured ~ ~;
accordin~ to the method déscriDed above. ~- -' . ~
The invention will now be described by way of example, with reference to the following non-limiting Examples.
. :
Cartridged water-in-oil emulsion explosives were prepared having the following compositions, in which all units are expressed as percentages or. a mass basis:
Constitue~lt Sample 1 Sample 2 Ammonium nitrate 68,60 65,98 Sodium nitrate 12,81 12,32 Thiourea 0,1 -l~ater 10,11 9,73 P9S*Oil 0,97 0,93 Crill 4*(sorbitan monooleate emulsifier) 1,36 1,31 Paraffin Wax (Aristo~ ~ 1,98 1,90 Microcrystalline Wax (BE SQUARE Amber)* 1,9g 1,90 Bentonite 2,00 2,00 Sodium nitrit~ ~20% m/m aqueous solution) 0,09 3M B23/500*Microballoons ^ 3,93 TOTAL 10G,00 100,00 Cold Density (g/cm3) 1,15 1,15 * Trade Mark 1 330~7 The P95* (trade name) mineral oil was obtained from BP South Africa (Proprietary) Limited, and the Crill 4* (trade name) from Croda Chemicals South Africa (Proprietary) Limited. The paraffin wax was Aristo* (trade name) wax obtained from Sasol Chemicals (Proprietary) Limited, and the microcrystalline wax was BE SQUARE Amber 175* (trade name) obtained from Bareco Inc. USA. The microballoons were 3M B23/500* (trade name) glass microballoons obtained from 3M South Africa (Proprietary) Limited. The bentonite was MX-80*VOLCL~Y
WESTERN BENTONITE-13T (trade name) obtained from American Colloid Company, and typically having the following chemical analysis: Si02 60,0-62,0~ m/m; Al2 03 21,0-23,0% m/m; Fe2 3 3,0-4,0% m/m; MgO 2,0-3,0% m/m; Na20 2,0-3,0% m/m; GaO ~-0,1-0,7% m/m; X20 0,4-0,5% m/m; and having a pH value of 8,5-10~0.
The amount of water given includes the water used to make up the sodium nitrite solution.
The emulsion explosives were prepared by forming a premix o~
water, ammonium nitrate, sodium nitrate, and thiourea at about 80 to 90C, and a second premix of the microcrystalline wax, paraffin wax, P95 oil and Crill 4 at about 70 to 80C. The first premix was then slowly added to the second premix with agitation to form a base emulsion. The bentonite was therea~ter admixed with the base emulsion in a low shear blender for about 1 minute to provide a thickened emulsion.
Samples 1 and 2 were prepared by respectively dispersing the sodium nitrite or the microballoons in the base emulsion in a blender at normal elevated working temperatures, followed by cartridging and rapid cooling. Comparative samples, identical ; ~
30 to Samples 1 and 2 save that they did not contain bentonite, ~`
were also made up.
*Trade Mark .
"_ Samples 1 and 2, with and without the bentonite, were tested according to the Stanhope cone penetrometer method (with 150 g cone), and the results obtained are set out in Table I.
TABLE I :~
LE - PENETRAlI~ -without bentonite ~ with benton (i) Temperature 30UC
Sample 1 22,5 18,0 Sample 2 13,5 7,8 ~ii.) Teme~ ature 50C
Sample 2 19,4 16,4 ~ :
(iii) Temperature 60C
Sample 2 23,4 17,3 The viscosi~y of Sample 2, with and without the bentonite, was measured at elevated temperatures, and the results are set out in Table II.
TABLE II
Temperature Viscosity ~ample 2 without Sample 2 with bentonite .bentonite Sample 2, with and without the bentonite, was also tested for minimun initiation ~MI) and velocity of detonation CVOD) at 40C, and the results are set out in Table III. Table III also sets out the results of tests for MI and VOD at 40C of a further sample ~ermed Sample ~, , . . .
; . .. . .
f. ~ ~
,~. :- ` , ` .
~, ~ : , . ,, . `
, ~ 3 ~
which is a formulation essentially similar to Sample 2 but which contains 4% by mass of the bentonite based on ~he mass of the emulsion.
In Table III, ~M' indicates a misfire, and '3D', '4D' and 'SD' indicate that the explosive could be detonated with a detonator containing 45mg, 90mg, and 180mg pentaethyritol tetranitrate respectively.
TABLE III
SAMPLE Detonation Characteristics at 40C
Initial After 4 months A~`ter 6 months Ml VOD MI V~ MI VO~
~km/s) ~km/s) ~km/s) Sample 2 3D 4,9 SD4,7 M8D
(without ` - bentonite) - - - -Sample 2 3D 4,7 4D` 4,7 5D 4,9 (with 2%
bentonite) Sample 3 3D 4,8 SD4,7 M8D
(4~ bentonite) -Sample 2, with and withcut bentonite, was tested for susceptibility to shock crystallization, and the results are set out in Table IV
(Temperature Rise on Shocking) and Table V ~Bubble Energy after ShocXing). Temperature rise on shocking was measured by placing a thermocouple in the centre of a cartridge suspended vertically at 6,7 m below the surface of water. A 150g booster was fired at the same depth at a distance of 2,8m from the cartridge and the ~esultant temperature 1 rise due to crystallisàtion was recorded. The average of three results is given in Table IV . Bubble energy after shocXing was measured by firing a 150g booster at varying distances from five cartridges ~ 3 ~ J
suspended vertically at a wa~er dep~h of 6,7m The cartridges were detonated 13 seconds later ~ld their bubble energy recorded as given in Table V. ~he same method of shocking was use~ ~or Sample 2 ~without bentonite) and Sample 2 ~wi~h bentonite).
TABLE IV :~ :
TEMPERATURE RISE ON SH0CKING -~
SAM~L~ Iemperature RlseI`ime taken to Keach (C) hlaximum Temperature ~S) ' ' Sample 2 2'~,3 360 (without bentonite) Sample 2 21,0 360 :-.~with bentonite) ., .
- TABLE V - . -;
BUBBLE ENER~Y AFTER SH0CKING
SAMPL~ Dist~ce from Booster~ubble Energy ::~
(m) ~MJ/kg) Sample 2 - 2,10 (without bentonite3 5 1 50 2 1,45 1,8 - 1?40 1,75 Mlsfire Sample 2 - 2,10 . ~
(with bentonite) 5 1,55 ~ :
2 1,45 1,8 1,40 : : `
1,75 Misfire ~ ~
.' ~;`.'.',''''~"~
~33~
Without wishing to be bound by theory, the Applicant believes ~hat thie desired increase in viscosity on addition of bent~nite to emulsion explosives is obtamed by the bentonite acting on components sudl as the wax on cooling, thereby causing swelling of these camponents (indicating modification of the cTys~al structure thereof) and hence thickening of the emulsion.
The increased emulsion viscosity pro~ides advantages such as higher degree of gas or air bubble retention and hence longer shelf life.
The addition of bentonite to emulsion explosives causes an increase in rigidity at all temperatures, but the resistance to softening at high temperatures is increased considerably, as seen from the ~iscosity (see Table II)-and cone penetration values (see Table I).
. ~
THIS INVENTION relates to an explosive. lt relates in particular to the manufacture of an emulsion explosive comprising a discontinuous phase which forms an oxidizing salt-containing component and a continuous 5 phase which is immiscible with the discontinuous phase and which forms a fuel component.
'""''':
Such explosives, when the oxidizing salt-containing component contains water and is in the form of an aqueous solution, are known as 'water-in-fuel' emulsions, and when Ihe oxidizirg salt component 10 contains little or no water, they can be regarded as 'm;it-in-fuel' emulsions.
' .;
According to the invention, in the manufacture of an emulsion explosive `~
comprising a discontinuous phase which for2s an oxidizing salt-containing component and a continuous phase ~ich is immiscible ;
15 witll the discontinuous phase and which forms a fuel component, there is 5 provided a method of thickening or increasing the viscosity of the emulsion which comprises dispersing insoluble parti~ulate benton]te in ;
at least o~e of the components of the emulsion.
The bentonite may be added to the emulsion formed after admixture of 20 s~id components, in a proportion o~ from about 1,0 tc about 5,0% by mass ` -~
- ~33~ J
based on the emulsion mass. The Applicant has found that the bentonite is thereby dispersed through the emulsion withou~ dissolving in eit~er of ~he c~nponents, and without causing crystallization.
The bentonite may be swellable sodium bentoni~e which is composed largely of the mineral montmorillonite. It may be of the so-called USA
tight-spec type having a degree of dry particle fineness as follows:
90% by mass minimu~ finer than US Sieve No. 40 and 10% by mass maximum finer than US Sieve No 200. In other words, at least 90~ by mass of the bentonite particles may have a particle size less than 425 microns and 15 at the most 10% by mass of the bentoni~e Farticles may have a particle size less than 75 microns. The average particle size of the bentonite particles may be from about î5 microns to about 425 microns, preferably from about 75 microns to abou-t 350 microns.
The sodium bentonite may be that which is commercially aYailable in powder form under the trade name h~-80*VOLCLAY h~STERN BENTONITE-l~T
from The AmeTican Colloid Company, and which has a water content of between 5 and 10~ by mass, a dry particle fineness of 10% by mass maximum retained on US Sieve No. 40 and 10% by mass maximum passing US
Sieve No. 200, and a wet particle ~ineness of at least 94% by mass being finer than US Sieve No. 20~ and at least 92% by mass being finer than US
Sieve No. 325.
The bentonite may be dispersed in the emulsion by admixture of the powder with the emulsion in a low shear blender.
.
The discontinuous phase may comprise at least one oxidizing salt ; 30 selected from the group cons;sting of ammonium nitrate, al~ali me~al f * Trade Mark :; .
. -3-~3~
nitTates, alkaline earth metal nitrates, ammonium perchlora~e, alkali metal perchlorates, and alkaline earth metal perchlora~es.
The discontinuous phase may comprise ammonium nitrate with at least one further compound selected from the group consisting of oxygen-releasing salts and fuels which, together with the ammonium nitrate, forms a melt which has a melting point which is lower than that of the ammonium nitrate. Said further compound may be sodium nitrate, calcium nitrate, urea, urea derivati~es such as thiourea, or the like. The discontinuous phase may in certain cases comprise water, which is kept to a minimum to avoid wasted energy arising from steam generation, but which is employed to facilitate melting/dissolving of the oxidi~ing salt component to avoid excessive high processing temperatures during formation of the base emulsion.
The fuel component of the emulsion may fonn from 2 tO 25% by mass of the emulsion, preferably about 3 to 12% by mass.
The fuel of the fuel component will be immiscible with and insoluble in water. Preferably, the fuel of the fuel component is non-self-explosive and is selected from at least one member of the group consisting of hydrocarbons, halogenated hydrocarbons and nitrated hydrocarbons.
Typically, said fuel comprises at least one wax selected from the group consisting of paraffin waxes, microcrystalline waxes and slack waxes, and it may comprise at least one member of the group consisting of mineral oils, fuel oils, lubricating oils, liquid paraffin, xylene, toluene, petrolatum and dinitrotoluene.
~33~7 The fuel may comprise an emulsifier or a mixture of suitable emulsifiers. The fuel component may thus comprise at least one elnulsifier selected from the group consisting of sorbitan sesquioleate, sorbitan monooleate, sorbitan monopalmitate~ sodium monostearate, sodium tristearate, the mono- and diglycerides of ~at-forming fatty acids, soya bean lecithin, derivatives of lanolin, alkyl benzene sulphonates, oleyl acid phosphate, laurylamine acetate, decaglycerol decaoleate, decaglycerol decastearate, 2-oleyl-4,4'-bis(hydroxymethyl~-2-oxazoline, polymeric emulsifiers containing polyethylene glycol backbones with fatty acid side chains and derivatives of polyisobutylene succinic anhydride.
The emulsifiers act as surfactants and stabilizers to promote the - formation of the emulsion and to resist crystallization and/or coalescence of the discontinuous phase.
The method may include the step of dispersing a density-reducing agent in the emulsion to form an emulsion having a densi~y of from 1,10 to 1,15 g/cm3 at 25C.
The density-reducing agent may be selected from the group consisting of microballoons, microspheres and gas bubbles. ln one embodiment, the eventual emulsion may thus include glass microballoons, microspheres of polymeric material or another form of density-reducing agent, to provide the emulsion with the final density of 1,10 to 1,15 g/cm3 at 25C. The emulsion may then comprise up to about 1~% by mass of glass microballoons (eg C15/250*glass microballoons available from 3M South Africa (Pty) Limited) or microspheres of a polymeric materi~l (eg EXPANCEL 642 DE*microspheres available from KemaNord AB, Sweden) 9 which ,~ * Trade Mark .
~3~3~
can further act to sensitize the explosive. Al~hough the mass of microballoons or microspheres included may be up to 10%, it is preferably less than 4,5~ by mass, based on the mass of the emulsion to which they are added. In anot~ler embodiment, the density-reducing agent may comprise air bubbles in the emulsion. The bubbles can then be mechanically induced eg by physical mixing or blowing, and/or chemically induced, eg by a chemical ~oaming agent such as sodium nitrite added to the emulsion.
, The inYention extellds to an emulsion explosive whenever m~nufactured ~ ~;
accordin~ to the method déscriDed above. ~- -' . ~
The invention will now be described by way of example, with reference to the following non-limiting Examples.
. :
Cartridged water-in-oil emulsion explosives were prepared having the following compositions, in which all units are expressed as percentages or. a mass basis:
Constitue~lt Sample 1 Sample 2 Ammonium nitrate 68,60 65,98 Sodium nitrate 12,81 12,32 Thiourea 0,1 -l~ater 10,11 9,73 P9S*Oil 0,97 0,93 Crill 4*(sorbitan monooleate emulsifier) 1,36 1,31 Paraffin Wax (Aristo~ ~ 1,98 1,90 Microcrystalline Wax (BE SQUARE Amber)* 1,9g 1,90 Bentonite 2,00 2,00 Sodium nitrit~ ~20% m/m aqueous solution) 0,09 3M B23/500*Microballoons ^ 3,93 TOTAL 10G,00 100,00 Cold Density (g/cm3) 1,15 1,15 * Trade Mark 1 330~7 The P95* (trade name) mineral oil was obtained from BP South Africa (Proprietary) Limited, and the Crill 4* (trade name) from Croda Chemicals South Africa (Proprietary) Limited. The paraffin wax was Aristo* (trade name) wax obtained from Sasol Chemicals (Proprietary) Limited, and the microcrystalline wax was BE SQUARE Amber 175* (trade name) obtained from Bareco Inc. USA. The microballoons were 3M B23/500* (trade name) glass microballoons obtained from 3M South Africa (Proprietary) Limited. The bentonite was MX-80*VOLCL~Y
WESTERN BENTONITE-13T (trade name) obtained from American Colloid Company, and typically having the following chemical analysis: Si02 60,0-62,0~ m/m; Al2 03 21,0-23,0% m/m; Fe2 3 3,0-4,0% m/m; MgO 2,0-3,0% m/m; Na20 2,0-3,0% m/m; GaO ~-0,1-0,7% m/m; X20 0,4-0,5% m/m; and having a pH value of 8,5-10~0.
The amount of water given includes the water used to make up the sodium nitrite solution.
The emulsion explosives were prepared by forming a premix o~
water, ammonium nitrate, sodium nitrate, and thiourea at about 80 to 90C, and a second premix of the microcrystalline wax, paraffin wax, P95 oil and Crill 4 at about 70 to 80C. The first premix was then slowly added to the second premix with agitation to form a base emulsion. The bentonite was therea~ter admixed with the base emulsion in a low shear blender for about 1 minute to provide a thickened emulsion.
Samples 1 and 2 were prepared by respectively dispersing the sodium nitrite or the microballoons in the base emulsion in a blender at normal elevated working temperatures, followed by cartridging and rapid cooling. Comparative samples, identical ; ~
30 to Samples 1 and 2 save that they did not contain bentonite, ~`
were also made up.
*Trade Mark .
"_ Samples 1 and 2, with and without the bentonite, were tested according to the Stanhope cone penetrometer method (with 150 g cone), and the results obtained are set out in Table I.
TABLE I :~
LE - PENETRAlI~ -without bentonite ~ with benton (i) Temperature 30UC
Sample 1 22,5 18,0 Sample 2 13,5 7,8 ~ii.) Teme~ ature 50C
Sample 2 19,4 16,4 ~ :
(iii) Temperature 60C
Sample 2 23,4 17,3 The viscosi~y of Sample 2, with and without the bentonite, was measured at elevated temperatures, and the results are set out in Table II.
TABLE II
Temperature Viscosity ~ample 2 without Sample 2 with bentonite .bentonite Sample 2, with and without the bentonite, was also tested for minimun initiation ~MI) and velocity of detonation CVOD) at 40C, and the results are set out in Table III. Table III also sets out the results of tests for MI and VOD at 40C of a further sample ~ermed Sample ~, , . . .
; . .. . .
f. ~ ~
,~. :- ` , ` .
~, ~ : , . ,, . `
, ~ 3 ~
which is a formulation essentially similar to Sample 2 but which contains 4% by mass of the bentonite based on ~he mass of the emulsion.
In Table III, ~M' indicates a misfire, and '3D', '4D' and 'SD' indicate that the explosive could be detonated with a detonator containing 45mg, 90mg, and 180mg pentaethyritol tetranitrate respectively.
TABLE III
SAMPLE Detonation Characteristics at 40C
Initial After 4 months A~`ter 6 months Ml VOD MI V~ MI VO~
~km/s) ~km/s) ~km/s) Sample 2 3D 4,9 SD4,7 M8D
(without ` - bentonite) - - - -Sample 2 3D 4,7 4D` 4,7 5D 4,9 (with 2%
bentonite) Sample 3 3D 4,8 SD4,7 M8D
(4~ bentonite) -Sample 2, with and withcut bentonite, was tested for susceptibility to shock crystallization, and the results are set out in Table IV
(Temperature Rise on Shocking) and Table V ~Bubble Energy after ShocXing). Temperature rise on shocking was measured by placing a thermocouple in the centre of a cartridge suspended vertically at 6,7 m below the surface of water. A 150g booster was fired at the same depth at a distance of 2,8m from the cartridge and the ~esultant temperature 1 rise due to crystallisàtion was recorded. The average of three results is given in Table IV . Bubble energy after shocXing was measured by firing a 150g booster at varying distances from five cartridges ~ 3 ~ J
suspended vertically at a wa~er dep~h of 6,7m The cartridges were detonated 13 seconds later ~ld their bubble energy recorded as given in Table V. ~he same method of shocking was use~ ~or Sample 2 ~without bentonite) and Sample 2 ~wi~h bentonite).
TABLE IV :~ :
TEMPERATURE RISE ON SH0CKING -~
SAM~L~ Iemperature RlseI`ime taken to Keach (C) hlaximum Temperature ~S) ' ' Sample 2 2'~,3 360 (without bentonite) Sample 2 21,0 360 :-.~with bentonite) ., .
- TABLE V - . -;
BUBBLE ENER~Y AFTER SH0CKING
SAMPL~ Dist~ce from Booster~ubble Energy ::~
(m) ~MJ/kg) Sample 2 - 2,10 (without bentonite3 5 1 50 2 1,45 1,8 - 1?40 1,75 Mlsfire Sample 2 - 2,10 . ~
(with bentonite) 5 1,55 ~ :
2 1,45 1,8 1,40 : : `
1,75 Misfire ~ ~
.' ~;`.'.',''''~"~
~33~
Without wishing to be bound by theory, the Applicant believes ~hat thie desired increase in viscosity on addition of bent~nite to emulsion explosives is obtamed by the bentonite acting on components sudl as the wax on cooling, thereby causing swelling of these camponents (indicating modification of the cTys~al structure thereof) and hence thickening of the emulsion.
The increased emulsion viscosity pro~ides advantages such as higher degree of gas or air bubble retention and hence longer shelf life.
The addition of bentonite to emulsion explosives causes an increase in rigidity at all temperatures, but the resistance to softening at high temperatures is increased considerably, as seen from the ~iscosity (see Table II)-and cone penetration values (see Table I).
Claims (15)
1. In the manufacture of an emulsion explosive comprising a discontinuous phase which forms an oxidizing salt-containing component and a continuous phase which is immiscible with the discontinuous phase and which forms a fuel component, a method of thickening or increasing the viscosity of the emulsion which comprises dispersing insoluble particulate bentonite in at least one of the components of the emulsion.
2. A method as claimed in Claim 1, in which the added to the emulsion formed after admixture of said components, in a proportion of from about 1,0 to about 5,0% by mass based on the emulsion mass.
3. A method as claimed in Claim 1 in which the bentonite is swellable sodium bentonite.
4. A method as claimed in Claim 1, Claim 2 or Claim 3, in which at least 90% by mass of the bentonite particles have a particle size less than 425 microns and at the most 10% by mass of the bentonite particles have a particle size less than 75 microns.
5. A method as claimed in Claim 4, in which the average particle size of the bentonite particles is from about 75 microns to about 425 microns.
6. A method as claimed in any one of Claims 1 to 3, in which the discontinuous phase comprises at least one oxidizing salt selected from the group consisting of ammonium nitrate, alkali metal nitrates, alkaline earth metal nitrates, ammonium perchlorate, alkali metal perchlorates, and alkaline earth metal perchlorates.
7. A method as claimed in Claim 6, in which the discontinuous phase comprises ammonium nitrate with at least one further compound selected from the group consisting of oxygen-releasing salts and fuels which, together with the ammonium nitrate, form a melt which has a melting point which is lower than that of the ammonium nitrate.
8. A method as claimed in any one of Claims 1 to 3, in which the fuel component forms from 2 to 25% by mass of the emulsion.
9. A method as claimed in any one of Claims 1 to 3, in which the fuel of the fuel component is non-self-explosive and is selected from the group consisting of hydrocarbons, halogenated hydrocarbons and nitrated hydrocarbons.
10. A method as claimed in Claim 9, in which said fuel comprises at least one wax selected from the group consisting of paraffin waxes, microcrystalline waxes and slack waxes.
11. A method as claimed in Claim 9 , in which the fuel of the fuel component comprises at least one member of the group consisting of mineral oils, fuel oils, lubricating oils, liquid paraffin, xylene, toluene, petrolatum and dinitrotoluene.
12. A method as claimed in any one of Claims 1 to 3, in which the fuel component comprises at least one emulsifier selected from the group consisting of sorbitan sesquioleate, sorbitan monooleate, sorbitan monopalmitate, sodium monostearate, sodium tristearate, the mono- and diglycerides of fat-forming fatty acids, soya bean lecithin, derivatives of lanolin, alkyl benzene sulphonates, oleyl acid phosphate, laurylamine acetate, decaglycerol decaoleate, decaglycerol decastearate, 2-oleyl-4,4'-bis(hydroxymethyl)-2-oxazoline, polymeric emulsifiers containing polyethylene glycol backbones with fatty acid side chains and derivatives of polyisobutylene succinic anhydride.
13. A method as claimed in any one of Claims l to 3, which includes the step of dispersing a density-reducing agent in the emulsion to form an emulsion having a density of from 1,10 to 1,15 g/cm3 at 25°C.
14. A method as claimed in Claim 13, in which the density-reducing agent is selected from the group consisting of microballoons, microspheres and gas bubbles.
15. An emulsion explosive whenever manufactured according to the method of any one of Claims 1 to 3.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA87/4690 | 1987-06-29 | ||
| ZA874690 | 1987-06-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1330397C true CA1330397C (en) | 1994-06-28 |
Family
ID=25578896
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000568451A Expired - Fee Related CA1330397C (en) | 1987-06-29 | 1988-06-02 | Emulsion explosive containing particulate insoluble bentonite |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0297740A3 (en) |
| AU (1) | AU616892B2 (en) |
| CA (1) | CA1330397C (en) |
| GB (1) | GB2206574B (en) |
| MW (1) | MW1888A1 (en) |
| NO (1) | NO882865L (en) |
| NZ (1) | NZ225094A (en) |
| ZW (1) | ZW8688A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ZA89991B (en) * | 1988-02-23 | 1989-10-25 | Ici Australia Operations | Explosive composition |
| NZ227918A (en) * | 1988-02-23 | 1992-03-26 | Ici Australia Operations | Emulsion explosive composition containing primary amine-poly(alk(en)yl)succinic acid condensate as emulsifier |
| US5389146A (en) * | 1993-04-12 | 1995-02-14 | Baroid Technology, Inc. | Grouting composition and method |
| AUPO679297A0 (en) * | 1997-05-15 | 1997-06-05 | Ici Australia Operations Proprietary Limited | Rheology modification and modifiers |
| CN108689784A (en) * | 2018-06-15 | 2018-10-23 | 中国矿业大学 | A kind of high density high-energy emulsion and preparation method thereof |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3126701A (en) * | 1964-03-31 | Process for generating gases | ||
| US2984556A (en) * | 1954-03-19 | 1961-05-16 | Shell Oil Co | Fuel composition and process for its manufacture |
| GB1306546A (en) * | 1970-06-09 | 1973-02-14 | Explosives & Chem Prod | Blasting explosive composition |
| GB1602187A (en) * | 1977-11-30 | 1981-11-11 | Nl Industries Inc | Method of increasing the viscosity of liquid organic systems and organophilic clay having enhanced dispersibility therein |
| US4426238A (en) * | 1979-09-14 | 1984-01-17 | Ireco Chemicals | Blasting composition containing particulate oxidizer salts |
| ATE45135T1 (en) * | 1983-03-18 | 1989-08-15 | Prb Nobel Explosifs Societe An | COMPOSITIONS OF THE ''EMULSION EXPLOSIVE'' TYPE, PROCESS FOR THEIR PREPARATION AND USE OF THESE COMPOSITIONS. |
| IE59303B1 (en) * | 1985-08-21 | 1994-02-09 | Ici Australia Ltd | Composition |
| US4678524A (en) * | 1986-06-18 | 1987-07-07 | Ireco Incorporated | Cast explosive composition and method |
| IN168892B (en) * | 1986-12-12 | 1991-07-06 | Ici India Ltd |
-
1988
- 1988-05-30 MW MW18/88A patent/MW1888A1/en unknown
- 1988-06-02 CA CA000568451A patent/CA1330397C/en not_active Expired - Fee Related
- 1988-06-08 GB GB8813578A patent/GB2206574B/en not_active Expired - Fee Related
- 1988-06-08 EP EP88305235A patent/EP0297740A3/en not_active Withdrawn
- 1988-06-20 NZ NZ225094A patent/NZ225094A/en unknown
- 1988-06-23 AU AU18319/88A patent/AU616892B2/en not_active Ceased
- 1988-06-27 ZW ZW86/88A patent/ZW8688A1/en unknown
- 1988-06-28 NO NO882865A patent/NO882865L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| NZ225094A (en) | 1990-12-21 |
| EP0297740A2 (en) | 1989-01-04 |
| GB2206574A (en) | 1989-01-11 |
| AU1831988A (en) | 1989-01-05 |
| GB2206574B (en) | 1990-10-03 |
| ZW8688A1 (en) | 1989-03-08 |
| NO882865L (en) | 1988-12-30 |
| AU616892B2 (en) | 1991-11-14 |
| NO882865D0 (en) | 1988-06-28 |
| MW1888A1 (en) | 1989-03-08 |
| GB8813578D0 (en) | 1988-07-13 |
| EP0297740A3 (en) | 1989-04-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |