CA1081966A - Detonating cord and process of manufacture - Google Patents
Detonating cord and process of manufactureInfo
- Publication number
- CA1081966A CA1081966A CA258,571A CA258571A CA1081966A CA 1081966 A CA1081966 A CA 1081966A CA 258571 A CA258571 A CA 258571A CA 1081966 A CA1081966 A CA 1081966A
- Authority
- CA
- Canada
- Prior art keywords
- detonating cord
- water
- cord according
- parts
- explosive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06C—DETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
- C06C5/00—Fuses, e.g. fuse cords
- C06C5/04—Detonating fuses
Abstract
ABSTRACT OF THE DISCLOSURE
Detonating cord comprising a detonable core component located within a casing component, the core com-ponent being characterized in that it comprises a mixture of high explosive material, preferably pentaerythritol tetranitrate, and a water bearing medium.
Detonating cord comprising a detonable core component located within a casing component, the core com-ponent being characterized in that it comprises a mixture of high explosive material, preferably pentaerythritol tetranitrate, and a water bearing medium.
Description
Tllis invention relates to ~usecord o~ a kind suitable for the transmission of detonation in blasting and seismic prospecting operations. The invention also includes methods of manufacturing such fusecord.
S Fusecord of this ~ind, commonly and hereinafter referred to as detonating cord, comprises a detonable core component located within a casing component. In one known general form such detonating cord comprises a core consisting of dry high explosive such as for example pentaerythritol tetranitrate (PETN) or cyclotrimethylenetrinitramine (RDX) surrounded by non explosive wrapping materials for example textile yarns and/
or synthetic plastics materials. The core is often encased in an envelope of paper or plastics film. Reinforcing yarns are applied around the envelope and a waterproof sheath o~ thermo-plastic material is applied over the yarns, usually by extrusion.In other forms, for example as described in Australian Patent 221849 (ICI Case 12496), detonating cords may be made by locating dry discrete solid high explosive particles in an encasing thermoplastic tube. Hitherto it has been considered essential that the high explosive component of detonating fusecord should be in a dry condition. Thus in commercial practice the high explosive was often incorporated into the detonating cord in a particulate freeflowing form devoid of water, which process was potentially hazardous and led to an undesirably high cost due to the necessity to invoke working conditions necessary to ':'-. ~ .' ~.
~ .
.. . :. :, . . ~ : ~ . . . . : . , . - . . . . . . . . . . .
''. ,'.''' " ' ' ': ' ' ' ~ ., ' ' ;'' .' ' lO~ifi~;
minimi~e the potential hazard. As an al~ernative procedure-the high explosive component was fed into the partially made detonat-ing cord in a dampened condition after which step the damping agent was removed by evaporation prior to the completion of the manufacture Oe the detona-ting cord. This alternative procedure tended to reduce rates Oe production and thus indirectly added to the cost of the product. Yet again so as to minimize the ingress of mo~sture from the atmosphere to the high explosive it is common, and often regulatory, practice to store such detonating cord in rooms which are kept at a higher temperature and at a lower humidity than the atmosphere external of the storage area, once more adding to the cost of the product prior to use. In addition so as to prevent the ingress of atmospheric moisture to an exposed high explosive core through an exposed end of the cord, additional cost was incurred by the provision of devices to protect and cover such exposed ends. Since the high explosive component of the detonating cord was in the form of finely divided particles capable of free flowing care had to be taken to ensure when using the cord that no accidental spillage of the high explosive component on to the working terrain occurred.
Surprisingly and in contradistinction to the teachings of the prior art it has now been found that the difficulties outlined above may be reduced substantially and sometimes .. . . . . . .
- .: ; ~ ,. ~ . ' . . , . :
, ' ' ' ' , ~l0131~66 eliminated by the provision in a de-tonating cord of a water-bearing core component.
Accordingly in a general form of the invention there is provided a detonating cord comprising a detonable core component S located within a casing component, said core component being characterized in that it comprises a mixture oP high explosive material and water-bearing material. We also provide a process for the manufacture of detonating cord which process comprises locating within an encasing component a detonable composition comprising a mixture of high explosive material and water bearing material. From amongst suitable water bearing materials there may be mentioned water itself which may be provided as a constituent of finely divided water wet high explosive material ;
used in the core component. Other suitable water bearing ~
materials include water bearing explosive compositions, for example explosive compositions commonly referred to as being of the water bearing slurry explosive type. Such slurry explosives are well known and comprise at least one inorganic oxygen releasing salt, water and fuel material. In a more preferred form the water bearing material is a water bearing ~urry ex-plosive comprising a thickening agent which optionally may be crosslinked.
The high explosive component of the core of the detonating cord of the invention is suitably a material which has been used conventionally to form high explosive cores in detonating .
..... . . . . : , . . , . :, . ................... .. .. . . . . ...
.' ' '' . ' ~ . , ' ' ''. ~' ' .' ' ;. " ' , ~0~ 66 s --cords of thc pr:ior art such as cyclotrimethylenetrinitramine (KDX). Other suitable materials include nitrates of carbo-hydrates such as nitrostarch or nitrocellulose, nitrates of polyhydric alcohols such as pentaerythritol tetranitrate ! 5 mannitol hexanitrate or erythrityl tetranitrate~ nitramines such as cyclotetramethylene tetranitramine (HMX), nitroaromatic compounds such as trinitrotoluene or nitroglycols such as ethylene glycol mononitrate. Pentaerythritol tetranitrate (PETN) is a particularly preferred material. If desired, mixturesof high explosive materials may be used as the high explosive component of the core. The high explosive component may be incorporated into the core in a dampened condition, for example as discrete particles or aggregates of particles wetted with water, methanol or a mixture of water and acetone.
Alternatively the high explosive component may be admixed in the form of an aqueous dispersion or paste with the other com-ponents of the core. Yet again the high explosive component may be added in a dry state to the water bearing material and incorporated therein. The size of the particles of the high explosive component suitably may be similar to the size of similar materials used in conventional detonating cords. Thus particles having a surface area of about 400 square centimetres per gram are ueeful. However the efficacy of the detonating cords of the invention is increased as the surface area of the particles is increased and it is preferred that the particles .. ~ ..
.. ~ :: . .. . . .
.; .
:: :
, ' , ' have a surface area of at least about 500 square centimetres per gram and particles having a surface area in the range from lO00 to 6000, for example erom about 2000 to 4000 square centimetres per gram are more preferred for most practical applications. Suitable cores are those comprising from 25% to 95% w/w, preferably ~ram 30% to 60% w/w, of the high water.
explosive component and up to 60Y, preferably up to 15~ w/w, of/
In the instance wherein the water bearing material is an explosive composition of the water bearing slurry type the inorganic oxidizing salt component thereof is suitably a nitrate of ammonium, an alkali metal or an alkaline earth metal. From amongst such salts it is preferred to use one or more salts selected from the group consisting of ammonium nitrate, sodium nitrate and calcium nitrate. If desired, similar salts derived from chloric acid or perchloric acid may be used but such salts are not essential as components of the cores~of the detonating cords of the invention.
Suitably the inorganic oxidizing salt component may constitute from 50 to 90~ w/w of the slurry explosive and amounts which constitute from 65 to 85% w/w of the slurry explosive are preferred. The particle size and shape of the oxygen releas-ing salt is not narrowly critical and is well known from the ~.
art of the manufacture of such salts. Powders and prilled particles are satisfactory.
The proportion of water in the slurry explosive component : .
:
,. , "; -, ,., ~:
.. ': ` `". ~' , '.
': ` ' ', " :
1081~ 6 should be sufficient to d:issolve at least a part oÇ the oxygen releasing salt and at least a part of any water soluble fuel which may be present. Suitably water may constitute from 5 to 35% w/w of the slurry explosive component but the amount presen-t should not be such that it prevents the detonation of the core of the detonating cord. Slurry ex-plosives wherein the amount of water constitutes from 8 to 25~ w/w, for example from 15 to 20~ w/w, of the slurry ex-plosive component are preferred.
The fuel materials in the slurry explosive component can be for example non explosive carbonaceous Çuels, non metallic fuels, metallic fuels or mixtures of such materials.
Such fuels include water soluble materials for example carbo-hydrates such as sugars or molasses, water soluble alcohols such as methanol, or water soluble glycols such as ethylene glycol or glues; water insoluble or sparingly water soluble materials such as mono nitrotoluene, sulphur, aluminium, silicon, ferrosilicon, ferrophosphorus, magnesium, titanium, boron, powdered polymeric material such as polyvinyl isobutyral, polyurethane or polystyrene, finely divided char-coaI, anthracite, gilsonite, asphalt, cellulosic materials such as paper pulp, woodpulp or sawdust, or cereal products such as flours, dextrins or starches. When the fuel material is a metal it is preferably in powdered or granulated form ranging in particle size from coarse, for example retained on '',''' ~'.
' : .
'`- : '':'' :. , ' ' ' ~
:., - . . : . : . ~: . . - :: :
- :
: ~ .
:~ , . ,: ' ~8~966 a 30 mesh ~ritish Standard Sieve, to very fine for example passing through a 300 mesh British Standard Sieve. Such metal may be in the form of discrete re~ular shaped particles, but metallic powders wherein the metal is in the form of irregular shaped particles or in flakes or in the form o~
aggregates of particles or flakes may also be used. ~ pre-ferred metallic fuel is aluminium. Suitably the water soluble fuel may constitute from 0.5 to 20% w/w, preferably from 2 to 15% w/w, of the slurry explosive component, whilst water insoluble or sparingly water soluble non metallic fuels may suitably constitute up to 10% w/w, preferably from 1 to 5% w/w, of the slurry explosive component, and the metallic water insoluble fuels may constitute up to 25% w/w, preferably from 0.5 to 20% w/w of the slurry explosive com-ponent.
In the instance where the slurry explosive componentcomprises a thickening agent, such a thickening~agent may be a naturally occurring material, a modified naturally occurring material or a synthetic material. Such thickening agents include gums of the galactomannan type or a derivative thereof, for example locust bean gum, guar gum or hydroxypropyl guar gum, or a biosynthetic gu~ such as for example the xanthan gums prepared by the microbal transformation of carbohydrate material, which gums are typified by gums prepared from glucose by treatment with micro-organisms of the genus ' ' ' . ~ --- - : -- ~
., . . ~ .
: . - , :
- . - .. .. :
:'': : ~ , ;
;6 _nthomonas ~or example the plant pathogen Xanthomonas campestris. Other suitable thickening agents include synthetic polymers such as polyacrylamide or copolymers such as may be derived from combinations of monomers for example acrylamide and methacryloylace-tone or from N-vinylpyrrolidone and 2-acetoacetoxyethylmethacrylate~ or from acrylamide, acrylonitrile and 2-acetoacetoxyethyl-methacrylate. Such thickening agents when used usually con-stitute from 0.1 to 5% w/w, typically from 0.5 to 3% w/w, of the slurry explosive component. When it is desired that the thickening agent may be crosslinked conventional cross-linking agents may be used. Typical crosslinking agents include materials such as chromium salts for example chromic halides or alkali metal dichrGmates, cerium salts such as ceric ammonium nitrate, or antimony salts such as potassium pyroantimonate. Alternatively a suitable degree of crosslinking may be achieved by means of a two component redox system for example a mixture of an alkali metal di-chromate and potassium antimony tartrate or arsenious oxide.
Such crosslinking agents when used usually constitute from about 0.001% to 0.5~ w/w of the slurry explosive component.
Another suitable water bearing thickener comprises naturally occurring products or derivatives thereof such as starches, dextrins or flours~ in admixture with an amount of water sufficient to form a dispersion, slurry or paste.
~' :
~:. , : - :
: ' "' :' ;'"''`'' ' " ''~ ' :
.: i : . , ~)8'~L9G6 -- 10 _ Such mixtures may iE desired by converted to a gelled form by suitable heat treatment.
The core components of the detonating cords of the invention may be prepared using mixing equipment suitable for handling high explosive materials of the kind typically referred to hereinbefore whereby the high explosive material may be admixed with the water-bearing material.
The order in which the ingredients of the core component are ~ ~ -admixed is not narrowly critical and wlll depend to some extent on the nature of the water bearing material. Thus for example the water bearing material may be prepared and the high explosive material incorporated therein.
Alternatively when the water bearing material is of a gellable type, gelation thereof may be effected prior to or subsequent to the addition of the high explosive material. Similarly when the water bearing material is an explosive material com-prising fuel material such as metallic fuel it is often con-venient to add some of such fuel as a final component of the core which is being prepared.
The casing component in which the core component is enclosed may be formed in situ as the detonating cord is being made, or it may be a preformed component. Thus for example the casing component may be of a type wherein the core is fed to a casing made in situ and comprising an envelope of paper or plastics film around which is applied reinforced ;, ~... . ~ , .
- . . : .: .- , ~ ' ' :
,.................. . ~ :
~o~9~
-yarns and over which i.s thcn extruded an abrasion resistant sheath o~ thermoplastic material. Procedures whereby such casings may be prepared are well ~nown and have been described in the prior art relating to the encasement of non-water-bearing cores used in detonating cords. Alternatively thecasing component may be in the form of a preformed tube which suitably may be of soft metal such as lead or an alloy there-of or of a thermoplastics composition comprising material such as polyamides, for example a nylon, polyolefins such as poly-propylene7 polyethylene or copolymers thereof such as may bederived from ethylene and vinyl esters typically vinyl acetate, polyesters such as polyethylene terephthalateg or polyvinyl-chloride. Rubber compositions derived from natural or synthetic rubbers are also useful. Such tubes iE desired may be of the rigid type for example they may be fabricated from non-plasticized or lightly plasticized polyvinylchloride compositions, but it is preferred that they be reasonably flexible, for example they may be made from plasticized polyvinylchloride compositions.
Flexible tubular casing components made from polyolefins, typically polyethylene or polypropylene are especially preferred.
Suitably the internal diameter of the casing component may be in the range from about 1/8 inch to about one inch~ but casings of an internal diameter beyond this range may be used if desired.
.
. .
... , . , ' ' ' :
~l~8196~
1 ~ --The casing components may have a plain outer surface~
but it is often advantageous to provide them with an exterior braiding or with a foamed exterior or with an exterior wherein the surface is not smooth, for example it may be ribbed or fluted, to provide the casing component with enhancedresistance to abrasion, tear and impact as well as providing the de-tonating cord witll good flexure or knot holding properties.
Dependent to some extent on the flo~ properties of the core component and the nature of the casing component, the core component may be fed to the casing component by pouring, injection or extrusion or by application of suction.
The detonating cords of the invention are advantageous over the detonating cords of the prior art in that the core components are less hazardous than the core components of the prior art. This has attendant advantages in that the cost relating to the maintenance of anti-hazardous conditions in the manufacturing areas may be reduced and the necessity to dry finely divided high explosive material prior to use is also reduced. Still further the costs relating to the storage of the cords of the invention after manufacture are reduced since there is no necessity to prevent the con-tamination of the core component by atmospheric moisture. Yet again the hazard due to accidental spillage of the core com-ponent is minimized. When the core component is in the form of an extrudable gelled composition, such compositions .
' ' ,, -., ~ ..................... ." ' ~ -,: . . ; . . i , .
~8~66 are particularly suitable for use in a preformed tubular casing. Such casings are cheaper than the conventional spun casings ~nd, when used, provide an additional cost saving over the spun detonating cords of the prior art. Since the water-bearing material in the core component is less costly than the high explosive material, the core component oP the invention is therefore cheaper than prior art cores of a similar weight and consistingentirely of high explosive material, thus leading to a reduction in costs in operations lQ wherein the detonating cords are used. The detonating cords of the invention may be used for purposes for which prior art detonating cords were used. Thus for example they may be used as individual cords or as a multiplicity of cords so as to form a shaped explosive, in seismic prospecting operations or in blasting operations such as smooth wall blasting in quarrying or presplitting in mining. By suitable choice of the proportions of the amounts of high explosive material and water-bearing material the velocity of detonation of the detonated core component may be controlled; this leads to savings in the utilization of energy required for any parti-cular detonating operation.
~ Certain of the compositions from which the core com-ponent of the invention is made are new. Whilst in the prior art relating to water bearing slurry explosive compositions comprising inorganic oxidizing salts lt has been proposed to '~ ' ' : . ,., , :
: ' ' ': ' , , .. . ,~: ,:
~8~96G
- 14 - :
use up to 50% w/w of the composition of a high explosive material as a fuel, as far as we are aware it has not been proposed to use such fuels in slurry explosive compositions in proportions in excess of the above value.
Accordingly we provide as a new composition a water-bearing explosive composition comprising at least one inorganic oxygen re].easing salt selected from the group con- .
sisting of the nitrates of ammonium, an alkali metal and an alkaline earth metal; water; and fuel material, said fuel material being characterized in that it comprises from 50%w/w to 95% w/w of the said composition of a high explosive material as hereinbefore described, preferably pentaerythritol tetranitrate.
, , .. ~.. - . , , ~ . .
'':' : . ,,., . , : .
, ' ~ : ' ': ~ : ' :; . .
~(~8 !L9~;6 -- 15 -- .
The invention is now illustrated by, but is in no way limited to, the following examples wherein all parts and percentages are on a weight basis unless otherwise specified.
Examples 1 to 6 inclusive A gelled explosive composition of a water-bearing slurry type was prepared by conventional means from the materials set out below.
Ammonium nitrate368 parts Calcium nitrate460 parts Ethylene glycol162 parts Water 306 parts Guar gum 10 parts Sodium dichromate 2 parts 15 to form a stock water-bearing material.
Portions of this stock water-bearing material were ad-mixed with varying amounts of dry pentaerythritol tetranitrate (PETN) which had a surface area as determined by an air permeability method of about 2500 square centimetres per gram ~to provide a gelled core component suitable for use in de-tonatis~g cord and in which the PETN was dispersed uniformly.
The resultant core material was extruded into a multiplicity of cylindrical tubes made from a thermoplastic composition and being three feet long and of differing internal diameters. ~ ~;
The resultant detonating cords were then detonated by means '~ . . ' ". : ~ ,. : .,. ~:
~8~66 o~ a No 8 aluminium detonator. The results obtained are shown in Table 1 which shows the ratio on a weight basis of stock water-bearing material to PETN in the core component, the type of thermoplastic composition from which the tube was made, the internal diameter of the tube expressed in inches, and the velocity of detonation (VOD) obtained and expressed as kilometres p0r second.
TABLE I
i __ . ~ .
Core Component Tube Exa~ple ~ VOD
Stock : PETN Composition Diameter . _ _ _ 1 1 : 1 Polyvinyl 3~16 6.7 chloride
S Fusecord of this ~ind, commonly and hereinafter referred to as detonating cord, comprises a detonable core component located within a casing component. In one known general form such detonating cord comprises a core consisting of dry high explosive such as for example pentaerythritol tetranitrate (PETN) or cyclotrimethylenetrinitramine (RDX) surrounded by non explosive wrapping materials for example textile yarns and/
or synthetic plastics materials. The core is often encased in an envelope of paper or plastics film. Reinforcing yarns are applied around the envelope and a waterproof sheath o~ thermo-plastic material is applied over the yarns, usually by extrusion.In other forms, for example as described in Australian Patent 221849 (ICI Case 12496), detonating cords may be made by locating dry discrete solid high explosive particles in an encasing thermoplastic tube. Hitherto it has been considered essential that the high explosive component of detonating fusecord should be in a dry condition. Thus in commercial practice the high explosive was often incorporated into the detonating cord in a particulate freeflowing form devoid of water, which process was potentially hazardous and led to an undesirably high cost due to the necessity to invoke working conditions necessary to ':'-. ~ .' ~.
~ .
.. . :. :, . . ~ : ~ . . . . : . , . - . . . . . . . . . . .
''. ,'.''' " ' ' ': ' ' ' ~ ., ' ' ;'' .' ' lO~ifi~;
minimi~e the potential hazard. As an al~ernative procedure-the high explosive component was fed into the partially made detonat-ing cord in a dampened condition after which step the damping agent was removed by evaporation prior to the completion of the manufacture Oe the detona-ting cord. This alternative procedure tended to reduce rates Oe production and thus indirectly added to the cost of the product. Yet again so as to minimize the ingress of mo~sture from the atmosphere to the high explosive it is common, and often regulatory, practice to store such detonating cord in rooms which are kept at a higher temperature and at a lower humidity than the atmosphere external of the storage area, once more adding to the cost of the product prior to use. In addition so as to prevent the ingress of atmospheric moisture to an exposed high explosive core through an exposed end of the cord, additional cost was incurred by the provision of devices to protect and cover such exposed ends. Since the high explosive component of the detonating cord was in the form of finely divided particles capable of free flowing care had to be taken to ensure when using the cord that no accidental spillage of the high explosive component on to the working terrain occurred.
Surprisingly and in contradistinction to the teachings of the prior art it has now been found that the difficulties outlined above may be reduced substantially and sometimes .. . . . . . .
- .: ; ~ ,. ~ . ' . . , . :
, ' ' ' ' , ~l0131~66 eliminated by the provision in a de-tonating cord of a water-bearing core component.
Accordingly in a general form of the invention there is provided a detonating cord comprising a detonable core component S located within a casing component, said core component being characterized in that it comprises a mixture oP high explosive material and water-bearing material. We also provide a process for the manufacture of detonating cord which process comprises locating within an encasing component a detonable composition comprising a mixture of high explosive material and water bearing material. From amongst suitable water bearing materials there may be mentioned water itself which may be provided as a constituent of finely divided water wet high explosive material ;
used in the core component. Other suitable water bearing ~
materials include water bearing explosive compositions, for example explosive compositions commonly referred to as being of the water bearing slurry explosive type. Such slurry explosives are well known and comprise at least one inorganic oxygen releasing salt, water and fuel material. In a more preferred form the water bearing material is a water bearing ~urry ex-plosive comprising a thickening agent which optionally may be crosslinked.
The high explosive component of the core of the detonating cord of the invention is suitably a material which has been used conventionally to form high explosive cores in detonating .
..... . . . . : , . . , . :, . ................... .. .. . . . . ...
.' ' '' . ' ~ . , ' ' ''. ~' ' .' ' ;. " ' , ~0~ 66 s --cords of thc pr:ior art such as cyclotrimethylenetrinitramine (KDX). Other suitable materials include nitrates of carbo-hydrates such as nitrostarch or nitrocellulose, nitrates of polyhydric alcohols such as pentaerythritol tetranitrate ! 5 mannitol hexanitrate or erythrityl tetranitrate~ nitramines such as cyclotetramethylene tetranitramine (HMX), nitroaromatic compounds such as trinitrotoluene or nitroglycols such as ethylene glycol mononitrate. Pentaerythritol tetranitrate (PETN) is a particularly preferred material. If desired, mixturesof high explosive materials may be used as the high explosive component of the core. The high explosive component may be incorporated into the core in a dampened condition, for example as discrete particles or aggregates of particles wetted with water, methanol or a mixture of water and acetone.
Alternatively the high explosive component may be admixed in the form of an aqueous dispersion or paste with the other com-ponents of the core. Yet again the high explosive component may be added in a dry state to the water bearing material and incorporated therein. The size of the particles of the high explosive component suitably may be similar to the size of similar materials used in conventional detonating cords. Thus particles having a surface area of about 400 square centimetres per gram are ueeful. However the efficacy of the detonating cords of the invention is increased as the surface area of the particles is increased and it is preferred that the particles .. ~ ..
.. ~ :: . .. . . .
.; .
:: :
, ' , ' have a surface area of at least about 500 square centimetres per gram and particles having a surface area in the range from lO00 to 6000, for example erom about 2000 to 4000 square centimetres per gram are more preferred for most practical applications. Suitable cores are those comprising from 25% to 95% w/w, preferably ~ram 30% to 60% w/w, of the high water.
explosive component and up to 60Y, preferably up to 15~ w/w, of/
In the instance wherein the water bearing material is an explosive composition of the water bearing slurry type the inorganic oxidizing salt component thereof is suitably a nitrate of ammonium, an alkali metal or an alkaline earth metal. From amongst such salts it is preferred to use one or more salts selected from the group consisting of ammonium nitrate, sodium nitrate and calcium nitrate. If desired, similar salts derived from chloric acid or perchloric acid may be used but such salts are not essential as components of the cores~of the detonating cords of the invention.
Suitably the inorganic oxidizing salt component may constitute from 50 to 90~ w/w of the slurry explosive and amounts which constitute from 65 to 85% w/w of the slurry explosive are preferred. The particle size and shape of the oxygen releas-ing salt is not narrowly critical and is well known from the ~.
art of the manufacture of such salts. Powders and prilled particles are satisfactory.
The proportion of water in the slurry explosive component : .
:
,. , "; -, ,., ~:
.. ': ` `". ~' , '.
': ` ' ', " :
1081~ 6 should be sufficient to d:issolve at least a part oÇ the oxygen releasing salt and at least a part of any water soluble fuel which may be present. Suitably water may constitute from 5 to 35% w/w of the slurry explosive component but the amount presen-t should not be such that it prevents the detonation of the core of the detonating cord. Slurry ex-plosives wherein the amount of water constitutes from 8 to 25~ w/w, for example from 15 to 20~ w/w, of the slurry ex-plosive component are preferred.
The fuel materials in the slurry explosive component can be for example non explosive carbonaceous Çuels, non metallic fuels, metallic fuels or mixtures of such materials.
Such fuels include water soluble materials for example carbo-hydrates such as sugars or molasses, water soluble alcohols such as methanol, or water soluble glycols such as ethylene glycol or glues; water insoluble or sparingly water soluble materials such as mono nitrotoluene, sulphur, aluminium, silicon, ferrosilicon, ferrophosphorus, magnesium, titanium, boron, powdered polymeric material such as polyvinyl isobutyral, polyurethane or polystyrene, finely divided char-coaI, anthracite, gilsonite, asphalt, cellulosic materials such as paper pulp, woodpulp or sawdust, or cereal products such as flours, dextrins or starches. When the fuel material is a metal it is preferably in powdered or granulated form ranging in particle size from coarse, for example retained on '',''' ~'.
' : .
'`- : '':'' :. , ' ' ' ~
:., - . . : . : . ~: . . - :: :
- :
: ~ .
:~ , . ,: ' ~8~966 a 30 mesh ~ritish Standard Sieve, to very fine for example passing through a 300 mesh British Standard Sieve. Such metal may be in the form of discrete re~ular shaped particles, but metallic powders wherein the metal is in the form of irregular shaped particles or in flakes or in the form o~
aggregates of particles or flakes may also be used. ~ pre-ferred metallic fuel is aluminium. Suitably the water soluble fuel may constitute from 0.5 to 20% w/w, preferably from 2 to 15% w/w, of the slurry explosive component, whilst water insoluble or sparingly water soluble non metallic fuels may suitably constitute up to 10% w/w, preferably from 1 to 5% w/w, of the slurry explosive component, and the metallic water insoluble fuels may constitute up to 25% w/w, preferably from 0.5 to 20% w/w of the slurry explosive com-ponent.
In the instance where the slurry explosive componentcomprises a thickening agent, such a thickening~agent may be a naturally occurring material, a modified naturally occurring material or a synthetic material. Such thickening agents include gums of the galactomannan type or a derivative thereof, for example locust bean gum, guar gum or hydroxypropyl guar gum, or a biosynthetic gu~ such as for example the xanthan gums prepared by the microbal transformation of carbohydrate material, which gums are typified by gums prepared from glucose by treatment with micro-organisms of the genus ' ' ' . ~ --- - : -- ~
., . . ~ .
: . - , :
- . - .. .. :
:'': : ~ , ;
;6 _nthomonas ~or example the plant pathogen Xanthomonas campestris. Other suitable thickening agents include synthetic polymers such as polyacrylamide or copolymers such as may be derived from combinations of monomers for example acrylamide and methacryloylace-tone or from N-vinylpyrrolidone and 2-acetoacetoxyethylmethacrylate~ or from acrylamide, acrylonitrile and 2-acetoacetoxyethyl-methacrylate. Such thickening agents when used usually con-stitute from 0.1 to 5% w/w, typically from 0.5 to 3% w/w, of the slurry explosive component. When it is desired that the thickening agent may be crosslinked conventional cross-linking agents may be used. Typical crosslinking agents include materials such as chromium salts for example chromic halides or alkali metal dichrGmates, cerium salts such as ceric ammonium nitrate, or antimony salts such as potassium pyroantimonate. Alternatively a suitable degree of crosslinking may be achieved by means of a two component redox system for example a mixture of an alkali metal di-chromate and potassium antimony tartrate or arsenious oxide.
Such crosslinking agents when used usually constitute from about 0.001% to 0.5~ w/w of the slurry explosive component.
Another suitable water bearing thickener comprises naturally occurring products or derivatives thereof such as starches, dextrins or flours~ in admixture with an amount of water sufficient to form a dispersion, slurry or paste.
~' :
~:. , : - :
: ' "' :' ;'"''`'' ' " ''~ ' :
.: i : . , ~)8'~L9G6 -- 10 _ Such mixtures may iE desired by converted to a gelled form by suitable heat treatment.
The core components of the detonating cords of the invention may be prepared using mixing equipment suitable for handling high explosive materials of the kind typically referred to hereinbefore whereby the high explosive material may be admixed with the water-bearing material.
The order in which the ingredients of the core component are ~ ~ -admixed is not narrowly critical and wlll depend to some extent on the nature of the water bearing material. Thus for example the water bearing material may be prepared and the high explosive material incorporated therein.
Alternatively when the water bearing material is of a gellable type, gelation thereof may be effected prior to or subsequent to the addition of the high explosive material. Similarly when the water bearing material is an explosive material com-prising fuel material such as metallic fuel it is often con-venient to add some of such fuel as a final component of the core which is being prepared.
The casing component in which the core component is enclosed may be formed in situ as the detonating cord is being made, or it may be a preformed component. Thus for example the casing component may be of a type wherein the core is fed to a casing made in situ and comprising an envelope of paper or plastics film around which is applied reinforced ;, ~... . ~ , .
- . . : .: .- , ~ ' ' :
,.................. . ~ :
~o~9~
-yarns and over which i.s thcn extruded an abrasion resistant sheath o~ thermoplastic material. Procedures whereby such casings may be prepared are well ~nown and have been described in the prior art relating to the encasement of non-water-bearing cores used in detonating cords. Alternatively thecasing component may be in the form of a preformed tube which suitably may be of soft metal such as lead or an alloy there-of or of a thermoplastics composition comprising material such as polyamides, for example a nylon, polyolefins such as poly-propylene7 polyethylene or copolymers thereof such as may bederived from ethylene and vinyl esters typically vinyl acetate, polyesters such as polyethylene terephthalateg or polyvinyl-chloride. Rubber compositions derived from natural or synthetic rubbers are also useful. Such tubes iE desired may be of the rigid type for example they may be fabricated from non-plasticized or lightly plasticized polyvinylchloride compositions, but it is preferred that they be reasonably flexible, for example they may be made from plasticized polyvinylchloride compositions.
Flexible tubular casing components made from polyolefins, typically polyethylene or polypropylene are especially preferred.
Suitably the internal diameter of the casing component may be in the range from about 1/8 inch to about one inch~ but casings of an internal diameter beyond this range may be used if desired.
.
. .
... , . , ' ' ' :
~l~8196~
1 ~ --The casing components may have a plain outer surface~
but it is often advantageous to provide them with an exterior braiding or with a foamed exterior or with an exterior wherein the surface is not smooth, for example it may be ribbed or fluted, to provide the casing component with enhancedresistance to abrasion, tear and impact as well as providing the de-tonating cord witll good flexure or knot holding properties.
Dependent to some extent on the flo~ properties of the core component and the nature of the casing component, the core component may be fed to the casing component by pouring, injection or extrusion or by application of suction.
The detonating cords of the invention are advantageous over the detonating cords of the prior art in that the core components are less hazardous than the core components of the prior art. This has attendant advantages in that the cost relating to the maintenance of anti-hazardous conditions in the manufacturing areas may be reduced and the necessity to dry finely divided high explosive material prior to use is also reduced. Still further the costs relating to the storage of the cords of the invention after manufacture are reduced since there is no necessity to prevent the con-tamination of the core component by atmospheric moisture. Yet again the hazard due to accidental spillage of the core com-ponent is minimized. When the core component is in the form of an extrudable gelled composition, such compositions .
' ' ,, -., ~ ..................... ." ' ~ -,: . . ; . . i , .
~8~66 are particularly suitable for use in a preformed tubular casing. Such casings are cheaper than the conventional spun casings ~nd, when used, provide an additional cost saving over the spun detonating cords of the prior art. Since the water-bearing material in the core component is less costly than the high explosive material, the core component oP the invention is therefore cheaper than prior art cores of a similar weight and consistingentirely of high explosive material, thus leading to a reduction in costs in operations lQ wherein the detonating cords are used. The detonating cords of the invention may be used for purposes for which prior art detonating cords were used. Thus for example they may be used as individual cords or as a multiplicity of cords so as to form a shaped explosive, in seismic prospecting operations or in blasting operations such as smooth wall blasting in quarrying or presplitting in mining. By suitable choice of the proportions of the amounts of high explosive material and water-bearing material the velocity of detonation of the detonated core component may be controlled; this leads to savings in the utilization of energy required for any parti-cular detonating operation.
~ Certain of the compositions from which the core com-ponent of the invention is made are new. Whilst in the prior art relating to water bearing slurry explosive compositions comprising inorganic oxidizing salts lt has been proposed to '~ ' ' : . ,., , :
: ' ' ': ' , , .. . ,~: ,:
~8~96G
- 14 - :
use up to 50% w/w of the composition of a high explosive material as a fuel, as far as we are aware it has not been proposed to use such fuels in slurry explosive compositions in proportions in excess of the above value.
Accordingly we provide as a new composition a water-bearing explosive composition comprising at least one inorganic oxygen re].easing salt selected from the group con- .
sisting of the nitrates of ammonium, an alkali metal and an alkaline earth metal; water; and fuel material, said fuel material being characterized in that it comprises from 50%w/w to 95% w/w of the said composition of a high explosive material as hereinbefore described, preferably pentaerythritol tetranitrate.
, , .. ~.. - . , , ~ . .
'':' : . ,,., . , : .
, ' ~ : ' ': ~ : ' :; . .
~(~8 !L9~;6 -- 15 -- .
The invention is now illustrated by, but is in no way limited to, the following examples wherein all parts and percentages are on a weight basis unless otherwise specified.
Examples 1 to 6 inclusive A gelled explosive composition of a water-bearing slurry type was prepared by conventional means from the materials set out below.
Ammonium nitrate368 parts Calcium nitrate460 parts Ethylene glycol162 parts Water 306 parts Guar gum 10 parts Sodium dichromate 2 parts 15 to form a stock water-bearing material.
Portions of this stock water-bearing material were ad-mixed with varying amounts of dry pentaerythritol tetranitrate (PETN) which had a surface area as determined by an air permeability method of about 2500 square centimetres per gram ~to provide a gelled core component suitable for use in de-tonatis~g cord and in which the PETN was dispersed uniformly.
The resultant core material was extruded into a multiplicity of cylindrical tubes made from a thermoplastic composition and being three feet long and of differing internal diameters. ~ ~;
The resultant detonating cords were then detonated by means '~ . . ' ". : ~ ,. : .,. ~:
~8~66 o~ a No 8 aluminium detonator. The results obtained are shown in Table 1 which shows the ratio on a weight basis of stock water-bearing material to PETN in the core component, the type of thermoplastic composition from which the tube was made, the internal diameter of the tube expressed in inches, and the velocity of detonation (VOD) obtained and expressed as kilometres p0r second.
TABLE I
i __ . ~ .
Core Component Tube Exa~ple ~ VOD
Stock : PETN Composition Diameter . _ _ _ 1 1 : 1 Polyvinyl 3~16 6.7 chloride
2 1 : 1 Polyvinyl 3/8 6.6 chloride
3 3 2 Polyethylene 5/16 5.2
4 3 : 2 Polypropylen l/4 5.8 7 : 3 Polyvinyl 3/8 5.5 chloride 6 1 : 1 Polyvinyl 1/8 *
chloride ;
. ~, , _ . . ' * In Example 6 the Iength of tube was~reduced to two feet. A
detonation was propagated but no numerical value of the VOD was determined.
Exam~le 7 An explosive stock water-bearing material was prepared as described in Examples 1 to 6 except that in the present example the ethylene glyco~ ingredient of those examples was ,. : . : . - .
, ,. ' , . . .
replaced by 162 parts of methanol. Equal parts of this stock water-bearing material and the dry PETN used in Examples 1 to 6 were mixed and used to form a detonating cord by ex-truding the gelled mixture into a polyethylene tube having an internal diameter of 1/4 inch. When the cord was detonated by conventional means the velocity of detonation was 7.7 kilometres per second.
Example 8 An explosive mixture was prepared from Ammonium nitrate prills300 parts Ammonium nitrate powder292 parts Sodium nitrate 120 parts Sugar 40 parts Water 120 parts Ethylene glycol 9 parts Gilsonite 8 parts Aluminium powder *90 parts Aluminlum powder **10 parts Guar gu~ 4-5 parts Potassium antimony tartrate 0.5 part * The bul~ of this powder was capable of passing through a 200 mesh British S~andard Sieve.
*~ The bulk of this powder was capable of passing through a 300 mesh British Standard Sieve.
To this mixture there was added with stirring 3400 parts of ' : . . ~ :
' , ' '' ~ : ,' ' . :
.
', '' :
.
6~;
, , PETN havin~ a surace area of about 2000 square centimetres per gram and which was wetted with 600 parts of water. To the composition so obtained there was added with stirring a solution containing 0.2 part of sodium dichromate and 5 1 5 parts of water. The resultant gelled core material was then located in a tube having an internal diameter of 1/2 inch.
The tube had been made by extruding a foamable composition comprising a copolymer of ethylene and vinyl acetate con-taining about 18~ w/w of vinyl acetate units. The die through which the tube had been extruded had a cross-sectioned profile such that the foamed wall of the tube was ribbed and fluted on its exterior. The detonating cord so produced was stored for one week at ambient temperature and humidity and thereafter several lengths were cut therefrom and detonated by conventional means. -;
Example 9 A gelled explosive composition consisting of A~monium nitrate720 parts 5ugar 50 parts Sulphur~ 30 parts Coarse atomized aluminium powder 50 parts Paint fine aluminium powder 20 parts Water 125 parts "Biopolymer" XB23~5 parts - :: - . :
was prepared in a manner conventionally used for the pre-paration of gelled water-bearing explosive slurries.
~ ~Biopolymer" XB23 is a registered trade name for a bio-polymeric gum produced by a process comprising the trans-formation of carbohydrate material by treatment with themicroorganism Xanthomonas campestris.
500 parts of this composition was admixed with 9500 parts of dry PETN which had a surface area of about 400 square centimetres per gram. The resultant gelled core material was fed to a polyethylene tube having an internal diameter of 1/2 inch and the detonating cord so obtained was detonated by conventional means.
Example 10 6 parts of thiourea was dissolved in 40 parts of water and added to 60 parts of an aqueous 5~ solution of a copolymer derived from acrylamide and 2-acetoacetoxyethylmethacrylate in a molar percentage of 99.5:0.5. To the solution so formed there was added 320 parts of ammonium nitrate, 110 parts of sodium nitrate and the resultant mixture was heated at 60C
until solution of the components was effected. Theré was then admixed into the solution so obtained 310 parts of ammonium nitrate, 75 parts of an atomized aluminium powder the bulk of which was capable of passing through a No 200 mesh British Standard Sieve, 25 parts of woodmeal and 1000 parts of dry PETN which had a surface area of about 2500 square centimetres :
' ''',' ' : ' ' ,"' .
1~8~ ;6 . .
per gram. When the mixture was homogeneous a solution of 2.5 parts of sodium dichromate in 3 parts of water wasadded and mixing was continued for -five minutes after which time 25 parts of paint fine aluminium powder the bulk nf which was capable of passing through a No 300 mesh ~ritish Standard Sieve was added and mixing was continued for one minute.
There was thus obtained a water-bearing friable composition suitable for use as a core component for a detonating cord.
The core component so obtained was loaded at a rate of 40 grams per metre into a pol~propylene tube 8 mm in diameter which was formed from a tape wrapped around the core so that its edges overlapped. The core contained yarn material to assist the ~low of the core component of the invention from a die, the yarn material consisting of two yarns of twis~ed cotton. The~polypropylene tube was surrounded by a spun layer of strands of nylon yarn and a countering layer of strands of the same nylon yarn. The countering layer was surrounded by a foamed sheath of a foamable polyethylene composition which ~ ~ was ln the form of a foamed annulus which had been extruded ~;~
from~a circular die in~a conrentional manner. ~There wàs thus obtained a detonating cord w~ich exhibited excellent resistance to abrasion, tear and impact, and had excellent flexure and knot holding properties.
A d~tonating compo~Ltion was prepared by m;xlng 53 `~ ' ' , ':
'::
.. ',.' ' '' : ' '," ".',," ' '', '' , ':, .''. ~.,'''~ ' ' ; ,'' - ~: "' ' ' ' ' : ' : ", ' : , ' ~ ' ' : ' ' ~ :
~,, :.': ' ', '' ' ' "
,' , . .
36~ :
_ 21 -parts o~ water with 47 parts o~ dry PETN which had a surface area ~f 4000 square centimetres per gram. The re-sultant core material was fed into a cylindrical tube made from a polyvinylchloride composition and having an internal diameter of 13 millimetres to form a detonating cord. The cord was detonated by means of a No 6 aluminium detonator.
The velocity of detonation was 5.4 kilometres per second.
Example 12 105 parts of sugar were dissvlved in a mixture of 345 parts of ammonium nitrate, 575 parts of calcium nitrate amd 210 parts of water. There was dispersed in the above composition 720 parts of dry PETN which had a surface area of 4000 square centimetres per gram, and then 100 parts of pre-gelled starch were added to the resultant product to provide a core material. The core material so obtained was placed into a cyllndrical tube having a diameter of 1/2 inch and fabricated from a composition comprising poly(ethylene tere-phthalate). The detonating cord thus obtained was detonated by conventional means.
~ Ll~_a~
A core material was prepared by the general procedure of Example 12 except that the PETN of that example was re-placed by 720 parts of a c~mposition having a surface area of 2000 square centimetres per gram and containing PETN and trinitrotoluene in a weigh~ ratio of 3:2. A detonating cord -i ' ~ .
.;
' ~,' : "' ~
.:
:: . . . . . .
~' '' ' . , ' ~ .
. .
~(1 8~ ?6~
- 22 _ was made by placing the core material in a cylindrical tube having a diameter oE 5/8 inch and fabricated from a nylon composition, and it was then detonated by conventional means.
S Example 14 The general procedure of Example 12 was repeated except that the sugar of that Example was replaced by 200 parts of methanol, the amount of PETN was reduced to 570 parts and the core material so produced was placed in a cylindrical tube of 1/4" diameter and fabricated from a polyethylene com-position. The detonating cord so produced was detonated by conventional means.
Exam~le 1~
Into a first hopper of a co-extrusion machine there was placed a quantity of granules of a copolymer of ethylene and vinyl acetate having a vinyl acetate content of 28% and a melt flow index of S. The granules were con~erted to a tubular form by extrusion in a conventional manner at a rate of 27 metres per minute, the temperature at the throat of the extruder being 80C and increasing to a head and die temperature of 105C. A detonable composition was prepared from ammonium nitrate 150 parts, calcium nitrate 260 parts, sugar 75 parts~ ethylene glycol 10 parts~ water 98 parts, guar gum 5 parts, sodium dichromate 2 parts and PETN having a surface area of 4000 square centimetres per gram 257 parts.
.- , . .
.
, . ,, ' . .' ~
:
10~1~66 ' .
This wa~er-bearing gelled composition was located in a second feed hopper of the co-extrusion machine and pumped to the head of the extruder and co-extruded into the plastic tube at a rate of 78 grams per metre of length of tube which S had an internal diameter of 13 millimetres. The flexible detonating cord so produced was detonated by conventional means, and the velocity of detonat;on was 4.7 kilometres per second.
Example 16 The general procedure of Example 15 was repeated except that in the present example a second hollow cylindrica;l tube extruded from the copolymer of Example 15 and having an internal diameter of 2 millimetres was introduced concurrently with the detonable composition into the tube of Example 15.
The second tube was located substantially centrally within the tube of Example 15 and the longitudinal axes of the two tubes were substantially parallel. The velocity of detonation ,~ ;
of the detonating cord so produced was 6.1 kilometres per second.
Example 17 Into a cylindrical tube having an internal diameter of 20 mm and fabricated from a trans polyisoprene composition there was placed a detonahle composition described in Example 1 to form a core material at the rate of 40 grams/metre of length of tube. A load was applied eO the detonating cord - ~ ', .. ' -' -,; "' '' . ~.
.: . , - . ., ~
'' ., ~ :,' , . ~ . . , ': : ' ' : - . . . . .
.. , . ., : ~ .
~L081~66 so produced so as to cold draw the cord in a manner such that 100 units of length were increased to 250 units of length and the internal diameter of the tube was reduced to 16 mm. By this procedure there was obtained a detonating S cord containing 16 grams of core per metre oP length and having enhanced toughness and strength characteristics in comparison with the undrawn product.
Example 18 The general procedure of Example 15 was repeated `
except that in the present example the diameter and wall thickness of the tube component of the detonating cord were varied from time to time during the extrusion process by varying the draw speed of the extrusion line. There was thus obtained within a detonating cord a multipIicity of lengths in which a length varied from an adjolning length in characteristics of detonation.
ExamPle 12 The general procedure of Example 2 was repeated except that in the present example no sodium dichromate was present in the stock water-bearing material. The detonating ~ -cord so produced was detonated by conventional means.
~ ' A detonable core CQmponent was made by mixing 2025 parts of ammonium nitrate, 3374 Parts of calcium nitrate~
1256 parts of water and 845 parts of hexamine, and to the .
.
~, . .
: ' ;. ~ " ' ' ~ ' ~08~!9fi6 - 25 _ mixture so obtained there was added 2500 parts of PETN
having a surface area of 4000 square centimetres per gram. ?
A detonating cord was made hy placing the core component in a cylindrical tube fabricated from a polyethylene S composition and having an internal diameter of 5 millimetres.
The cord was detonated by means of a No 6 aluminium detonator.
Example 21 A detonable core component was made by mixing 1804 parts of ammonium nitrate, 3006 parts of calcium nitrate, 1119 parts of water and 1071 parts of sugar and to the mixture so obtained there was added 3000 parts of PETN having a sur~ ;
face area of 4000 square centimetres per gram. This core component was loaded into a cylindrical tube fabricated from `
a polyethylene composition and having an internal diameter f 4 millimetres. A velocity of detonation of 3.8 kilometres per second was obtained when the cord was detonated by means of a No 6 aluminium detonator.
Exam~
The general procedure of Example 5 was repeated except ....
that the PETN of that example was replaced by PETN having a surface area of 4700 square centimetres per gram. The velocity . ..
of detonation which was obtained was 5.7 kilometres per second.
Example 23 A detonable core component was made by mixing 1620 parts of ammonium nitrate, 2700 parts of calcium nibrate, 1005 parts ,,~. ' '~ .
.,.~ .
;~', '.
`. . - : - . :, . .
' " " ' ' " '' ~081~66 .
of water and 675 parts of hexamine, and to the mixture so obtained there was added 4000 parts of RDX having a surface area of 3000 square centimetres per gram. A detonating cord was made by placing the core component in a cylindrical tube S fabricated from a polyethylene composition and having an internal diameter of 13 millimetres. The cord was detonated by means o a No 8 ~lw inium det~nator.
;:
' ' "
' ' - '` ' '; ' ' . `:
.. .
- , - ; -- ~
:
chloride ;
. ~, , _ . . ' * In Example 6 the Iength of tube was~reduced to two feet. A
detonation was propagated but no numerical value of the VOD was determined.
Exam~le 7 An explosive stock water-bearing material was prepared as described in Examples 1 to 6 except that in the present example the ethylene glyco~ ingredient of those examples was ,. : . : . - .
, ,. ' , . . .
replaced by 162 parts of methanol. Equal parts of this stock water-bearing material and the dry PETN used in Examples 1 to 6 were mixed and used to form a detonating cord by ex-truding the gelled mixture into a polyethylene tube having an internal diameter of 1/4 inch. When the cord was detonated by conventional means the velocity of detonation was 7.7 kilometres per second.
Example 8 An explosive mixture was prepared from Ammonium nitrate prills300 parts Ammonium nitrate powder292 parts Sodium nitrate 120 parts Sugar 40 parts Water 120 parts Ethylene glycol 9 parts Gilsonite 8 parts Aluminium powder *90 parts Aluminlum powder **10 parts Guar gu~ 4-5 parts Potassium antimony tartrate 0.5 part * The bul~ of this powder was capable of passing through a 200 mesh British S~andard Sieve.
*~ The bulk of this powder was capable of passing through a 300 mesh British Standard Sieve.
To this mixture there was added with stirring 3400 parts of ' : . . ~ :
' , ' '' ~ : ,' ' . :
.
', '' :
.
6~;
, , PETN havin~ a surace area of about 2000 square centimetres per gram and which was wetted with 600 parts of water. To the composition so obtained there was added with stirring a solution containing 0.2 part of sodium dichromate and 5 1 5 parts of water. The resultant gelled core material was then located in a tube having an internal diameter of 1/2 inch.
The tube had been made by extruding a foamable composition comprising a copolymer of ethylene and vinyl acetate con-taining about 18~ w/w of vinyl acetate units. The die through which the tube had been extruded had a cross-sectioned profile such that the foamed wall of the tube was ribbed and fluted on its exterior. The detonating cord so produced was stored for one week at ambient temperature and humidity and thereafter several lengths were cut therefrom and detonated by conventional means. -;
Example 9 A gelled explosive composition consisting of A~monium nitrate720 parts 5ugar 50 parts Sulphur~ 30 parts Coarse atomized aluminium powder 50 parts Paint fine aluminium powder 20 parts Water 125 parts "Biopolymer" XB23~5 parts - :: - . :
was prepared in a manner conventionally used for the pre-paration of gelled water-bearing explosive slurries.
~ ~Biopolymer" XB23 is a registered trade name for a bio-polymeric gum produced by a process comprising the trans-formation of carbohydrate material by treatment with themicroorganism Xanthomonas campestris.
500 parts of this composition was admixed with 9500 parts of dry PETN which had a surface area of about 400 square centimetres per gram. The resultant gelled core material was fed to a polyethylene tube having an internal diameter of 1/2 inch and the detonating cord so obtained was detonated by conventional means.
Example 10 6 parts of thiourea was dissolved in 40 parts of water and added to 60 parts of an aqueous 5~ solution of a copolymer derived from acrylamide and 2-acetoacetoxyethylmethacrylate in a molar percentage of 99.5:0.5. To the solution so formed there was added 320 parts of ammonium nitrate, 110 parts of sodium nitrate and the resultant mixture was heated at 60C
until solution of the components was effected. Theré was then admixed into the solution so obtained 310 parts of ammonium nitrate, 75 parts of an atomized aluminium powder the bulk of which was capable of passing through a No 200 mesh British Standard Sieve, 25 parts of woodmeal and 1000 parts of dry PETN which had a surface area of about 2500 square centimetres :
' ''',' ' : ' ' ,"' .
1~8~ ;6 . .
per gram. When the mixture was homogeneous a solution of 2.5 parts of sodium dichromate in 3 parts of water wasadded and mixing was continued for -five minutes after which time 25 parts of paint fine aluminium powder the bulk nf which was capable of passing through a No 300 mesh ~ritish Standard Sieve was added and mixing was continued for one minute.
There was thus obtained a water-bearing friable composition suitable for use as a core component for a detonating cord.
The core component so obtained was loaded at a rate of 40 grams per metre into a pol~propylene tube 8 mm in diameter which was formed from a tape wrapped around the core so that its edges overlapped. The core contained yarn material to assist the ~low of the core component of the invention from a die, the yarn material consisting of two yarns of twis~ed cotton. The~polypropylene tube was surrounded by a spun layer of strands of nylon yarn and a countering layer of strands of the same nylon yarn. The countering layer was surrounded by a foamed sheath of a foamable polyethylene composition which ~ ~ was ln the form of a foamed annulus which had been extruded ~;~
from~a circular die in~a conrentional manner. ~There wàs thus obtained a detonating cord w~ich exhibited excellent resistance to abrasion, tear and impact, and had excellent flexure and knot holding properties.
A d~tonating compo~Ltion was prepared by m;xlng 53 `~ ' ' , ':
'::
.. ',.' ' '' : ' '," ".',," ' '', '' , ':, .''. ~.,'''~ ' ' ; ,'' - ~: "' ' ' ' ' : ' : ", ' : , ' ~ ' ' : ' ' ~ :
~,, :.': ' ', '' ' ' "
,' , . .
36~ :
_ 21 -parts o~ water with 47 parts o~ dry PETN which had a surface area ~f 4000 square centimetres per gram. The re-sultant core material was fed into a cylindrical tube made from a polyvinylchloride composition and having an internal diameter of 13 millimetres to form a detonating cord. The cord was detonated by means of a No 6 aluminium detonator.
The velocity of detonation was 5.4 kilometres per second.
Example 12 105 parts of sugar were dissvlved in a mixture of 345 parts of ammonium nitrate, 575 parts of calcium nitrate amd 210 parts of water. There was dispersed in the above composition 720 parts of dry PETN which had a surface area of 4000 square centimetres per gram, and then 100 parts of pre-gelled starch were added to the resultant product to provide a core material. The core material so obtained was placed into a cyllndrical tube having a diameter of 1/2 inch and fabricated from a composition comprising poly(ethylene tere-phthalate). The detonating cord thus obtained was detonated by conventional means.
~ Ll~_a~
A core material was prepared by the general procedure of Example 12 except that the PETN of that example was re-placed by 720 parts of a c~mposition having a surface area of 2000 square centimetres per gram and containing PETN and trinitrotoluene in a weigh~ ratio of 3:2. A detonating cord -i ' ~ .
.;
' ~,' : "' ~
.:
:: . . . . . .
~' '' ' . , ' ~ .
. .
~(1 8~ ?6~
- 22 _ was made by placing the core material in a cylindrical tube having a diameter oE 5/8 inch and fabricated from a nylon composition, and it was then detonated by conventional means.
S Example 14 The general procedure of Example 12 was repeated except that the sugar of that Example was replaced by 200 parts of methanol, the amount of PETN was reduced to 570 parts and the core material so produced was placed in a cylindrical tube of 1/4" diameter and fabricated from a polyethylene com-position. The detonating cord so produced was detonated by conventional means.
Exam~le 1~
Into a first hopper of a co-extrusion machine there was placed a quantity of granules of a copolymer of ethylene and vinyl acetate having a vinyl acetate content of 28% and a melt flow index of S. The granules were con~erted to a tubular form by extrusion in a conventional manner at a rate of 27 metres per minute, the temperature at the throat of the extruder being 80C and increasing to a head and die temperature of 105C. A detonable composition was prepared from ammonium nitrate 150 parts, calcium nitrate 260 parts, sugar 75 parts~ ethylene glycol 10 parts~ water 98 parts, guar gum 5 parts, sodium dichromate 2 parts and PETN having a surface area of 4000 square centimetres per gram 257 parts.
.- , . .
.
, . ,, ' . .' ~
:
10~1~66 ' .
This wa~er-bearing gelled composition was located in a second feed hopper of the co-extrusion machine and pumped to the head of the extruder and co-extruded into the plastic tube at a rate of 78 grams per metre of length of tube which S had an internal diameter of 13 millimetres. The flexible detonating cord so produced was detonated by conventional means, and the velocity of detonat;on was 4.7 kilometres per second.
Example 16 The general procedure of Example 15 was repeated except that in the present example a second hollow cylindrica;l tube extruded from the copolymer of Example 15 and having an internal diameter of 2 millimetres was introduced concurrently with the detonable composition into the tube of Example 15.
The second tube was located substantially centrally within the tube of Example 15 and the longitudinal axes of the two tubes were substantially parallel. The velocity of detonation ,~ ;
of the detonating cord so produced was 6.1 kilometres per second.
Example 17 Into a cylindrical tube having an internal diameter of 20 mm and fabricated from a trans polyisoprene composition there was placed a detonahle composition described in Example 1 to form a core material at the rate of 40 grams/metre of length of tube. A load was applied eO the detonating cord - ~ ', .. ' -' -,; "' '' . ~.
.: . , - . ., ~
'' ., ~ :,' , . ~ . . , ': : ' ' : - . . . . .
.. , . ., : ~ .
~L081~66 so produced so as to cold draw the cord in a manner such that 100 units of length were increased to 250 units of length and the internal diameter of the tube was reduced to 16 mm. By this procedure there was obtained a detonating S cord containing 16 grams of core per metre oP length and having enhanced toughness and strength characteristics in comparison with the undrawn product.
Example 18 The general procedure of Example 15 was repeated `
except that in the present example the diameter and wall thickness of the tube component of the detonating cord were varied from time to time during the extrusion process by varying the draw speed of the extrusion line. There was thus obtained within a detonating cord a multipIicity of lengths in which a length varied from an adjolning length in characteristics of detonation.
ExamPle 12 The general procedure of Example 2 was repeated except that in the present example no sodium dichromate was present in the stock water-bearing material. The detonating ~ -cord so produced was detonated by conventional means.
~ ' A detonable core CQmponent was made by mixing 2025 parts of ammonium nitrate, 3374 Parts of calcium nitrate~
1256 parts of water and 845 parts of hexamine, and to the .
.
~, . .
: ' ;. ~ " ' ' ~ ' ~08~!9fi6 - 25 _ mixture so obtained there was added 2500 parts of PETN
having a surface area of 4000 square centimetres per gram. ?
A detonating cord was made hy placing the core component in a cylindrical tube fabricated from a polyethylene S composition and having an internal diameter of 5 millimetres.
The cord was detonated by means of a No 6 aluminium detonator.
Example 21 A detonable core component was made by mixing 1804 parts of ammonium nitrate, 3006 parts of calcium nitrate, 1119 parts of water and 1071 parts of sugar and to the mixture so obtained there was added 3000 parts of PETN having a sur~ ;
face area of 4000 square centimetres per gram. This core component was loaded into a cylindrical tube fabricated from `
a polyethylene composition and having an internal diameter f 4 millimetres. A velocity of detonation of 3.8 kilometres per second was obtained when the cord was detonated by means of a No 6 aluminium detonator.
Exam~
The general procedure of Example 5 was repeated except ....
that the PETN of that example was replaced by PETN having a surface area of 4700 square centimetres per gram. The velocity . ..
of detonation which was obtained was 5.7 kilometres per second.
Example 23 A detonable core component was made by mixing 1620 parts of ammonium nitrate, 2700 parts of calcium nibrate, 1005 parts ,,~. ' '~ .
.,.~ .
;~', '.
`. . - : - . :, . .
' " " ' ' " '' ~081~66 .
of water and 675 parts of hexamine, and to the mixture so obtained there was added 4000 parts of RDX having a surface area of 3000 square centimetres per gram. A detonating cord was made by placing the core component in a cylindrical tube S fabricated from a polyethylene composition and having an internal diameter of 13 millimetres. The cord was detonated by means o a No 8 ~lw inium det~nator.
;:
' ' "
' ' - '` ' '; ' ' . `:
.. .
- , - ; -- ~
:
Claims (26)
1. A detonating cord comprising a detonable core com-ponent located within a casing component, said core component being characterized in that it comprises a mixture of high explosive material and water bearing material.
2. A detonating cord according to Claim 1 wherein said water bearing material is water.
3. A detonating cord according to Claim 1 wherein said water bearing material is a water bearing explosive composition.
4. A detonating cord according to Claim 3 wherein the said explosive composition is a water bearing explosive com-prising at least one inorganic oxygen releasing salt, water and fuel material.
5. A detonating cord according to Claim 4 wherein the said explosive composition comprises firstly at least one oxygen releasing salt selected from the group of the nitrate, chlorate and perchlorate of ammonium, alkali metals and alkaline earth metals present in an amount from 50 to 90 parts;
secondly water present in an amount from 5 to 35 parts;
thirdly at least one fuel material selected from the group consisting of water soluble fuel present in an amount from 0.5 to 20 parts, non-metallic sparingly water soluble fuel and non-metallic water insoluble fuel present in an amount up to 10 parts and metallic water insoluble fuel present in an amount up to 25 parts, all parts being by weight per 100 parts by weight of the said composition.
secondly water present in an amount from 5 to 35 parts;
thirdly at least one fuel material selected from the group consisting of water soluble fuel present in an amount from 0.5 to 20 parts, non-metallic sparingly water soluble fuel and non-metallic water insoluble fuel present in an amount up to 10 parts and metallic water insoluble fuel present in an amount up to 25 parts, all parts being by weight per 100 parts by weight of the said composition.
6. A detonating cord according to Claim 4 wherein the said explosive composition comprises a thickening agent.
7. A detonating cord according to Claim 6 wherein the said thickening agent is selected from the group consisting of galactomannan gums, xanthan gums and synthetic polymeric materials derived from acrylamide.
8. A detonating cord according to Claim 7 wherein the said thickening agent is selected from the group consisting of guar gum, biosynthetic gum which has been derived from a carbohydrate which has been reacted with Xanthomonas campestris, and copolymeric material containing mer units of acrylamide and 2-acetoacetoxyethylmethacrylate.
9. A detonating cord according to Claim 7 wherein the said thickening agent constitutes from 0.1 to 5% w/w of the said explosive composition.
10. A detonating cord according to Claim 7 wherein said explosive composition comprises at least one agent which crosslinks said thickening agent.
11. A detonating cord according to Claim 10 wherein the said agent constitutes from 0.001 to 0.5% w/w of the said explosive composition.
12. A detonating cord according to Claim 4 wherein the said oxygen releasing salt is selected from the group con-sisting of ammonium nitrate, calcium nitrate and sodium nitrate.
13 A detonating cord according to Claim 4 wherein water constitutes from 8 to 25% w/w of the said explosive composition.
14. A detonating cord according to Claim 1 wherein the said high explosive material is selected from the group consisting of nitrates of polyhydric alcohols, nitramines and nitro-aromatic compounds.
15. A detonating cord according to Claim 14 wherein the said high explosive material comprises pentaerythritol tetranitrate.
16. A detonating cord according to Claim 14 wherein the said high explosive material comprises trinitrotoluene.
17. A detonating cord according to Claim 14 wherein the said high explosive material comprises cyclotrimethylene-trinitramine,
18. A detonating cord according to Claim 1 wherein the said high explosive material has a surface area in the range from 400 to 6000 square centimetres per gram.
19. A detonating cord according to Claim 1 wherein the said high explosive material has a surface area in the range from 2000 to 4000 square centimetres per gram.
20. A detonating cord according to Claim 1 wherein the said high explosive material constitutes from 25% to 95%
w/w of the said core component.
w/w of the said core component.
21. A detonating cord according to Claim 1 wherein the said high explosive material constitutes from 30% to 60% w/w of the said core component.
22. A detonating cord according to Claim 1 wherein water constitutes up to 60% w/w of the said core component.
23. A detonating cord according to Claim 1 wherein water constitutes up to 15% w/w of the said core component.
24. A process for the manufacture of a detonating cord which process comprises locating within an encasing component a detonable composition comprising a mixture of high explosive material and water bearing material.
25. A detonating cord as claimed in Claim 1 wherein the mixture of high explosive material and water bearing material comprises at least one inorganic oxygen releasing salt selected from the group consisting of the nitrates of ammonium, and alkali metal and an alkaline earth metal; water; and fuel material, said fuel material being characterized in that it comprises from 50% to 95% w/w of the said composition of a high explosive.
26. A detonating cord according to Claim 25 wherein the said high explosive is pentaerythritol tetranitrate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPC.2690 | 1975-08-07 | ||
| AUPC269075 | 1975-08-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1081966A true CA1081966A (en) | 1980-07-22 |
Family
ID=3766313
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA258,571A Expired CA1081966A (en) | 1975-08-07 | 1976-08-06 | Detonating cord and process of manufacture |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5234910A (en) |
| AU (1) | AU1598476A (en) |
| BR (1) | BR7604914A (en) |
| CA (1) | CA1081966A (en) |
| DE (1) | DE2635479A1 (en) |
| FR (1) | FR2320521A1 (en) |
| ZA (1) | ZA764346B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4322719C1 (en) * | 1993-07-08 | 1994-10-13 | Gnaschwitz Sprengstoffwerk | Process for producing a detonating cord having a reduced adjustable detonation velocity |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL121244C (en) * | 1900-01-01 | |||
| FR1223343A (en) * | 1957-11-21 | 1960-06-16 | Explosive composition | |
| FR1299973A (en) * | 1961-09-11 | 1962-07-27 | Hirschmann Radiotechnik | Terminal button for retractable telescopic antennas |
| CA882848A (en) * | 1969-11-10 | 1971-10-05 | M. Welsh David | Composite detonating cord |
| US3765967A (en) * | 1972-03-23 | 1973-10-16 | Iresco Chemicals | Liquid and slurry explosives of controlled high sensitivity |
| US3912560A (en) * | 1974-01-31 | 1975-10-14 | Teledyne Mccormick Sleph | Thin layer propagating slurry explosive |
-
1975
- 1975-08-07 AU AU15984/76A patent/AU1598476A/en not_active Expired
-
1976
- 1976-07-21 ZA ZA00764346A patent/ZA764346B/en unknown
- 1976-07-28 BR BR7604914A patent/BR7604914A/en unknown
- 1976-08-05 JP JP51092843A patent/JPS5234910A/en active Pending
- 1976-08-06 FR FR7624143A patent/FR2320521A1/en not_active Withdrawn
- 1976-08-06 CA CA258,571A patent/CA1081966A/en not_active Expired
- 1976-08-06 DE DE19762635479 patent/DE2635479A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| AU1598476A (en) | 1978-01-19 |
| ZA764346B (en) | 1978-03-29 |
| FR2320521A1 (en) | 1977-03-04 |
| BR7604914A (en) | 1977-08-09 |
| JPS5234910A (en) | 1977-03-17 |
| DE2635479A1 (en) | 1977-02-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US2982210A (en) | Connecting cord | |
| CA1146807A (en) | Device for transmitting an explosive signal including a self-oxidizing material within an elongated tube | |
| CA2087444C (en) | Polymer mixture for producing films | |
| US3455749A (en) | Particulate explosive coated with discrete particles of polytetrafluoroethylene | |
| JPH08225388A (en) | Method of continuously producing pyrowork charge and composition obtained thereby | |
| US4033264A (en) | Explosive cartridge | |
| NZ206983A (en) | Dynamite explosive composition | |
| US3297502A (en) | Explosive composition containing coated metallic fuel | |
| US4230041A (en) | Explosive fuze cord | |
| CA1081966A (en) | Detonating cord and process of manufacture | |
| US4693763A (en) | Wet loading explosive | |
| US3097121A (en) | Powdered ammonium nitrate explosive containing polyacrylamide and an inorganic cross-linking agent | |
| WO2003053884A1 (en) | Explosive | |
| US3586551A (en) | Water-degradable cap-sensitive selfsupporting explosive | |
| US3726216A (en) | Detonation device and method for making the same | |
| CA1110852A (en) | Slurry explosive compositions | |
| US3457126A (en) | Aqueous explosive composition containing a porous water insoluble synthetic organic polymeric cellular material | |
| CA1197688A (en) | Perchlorate slurry explosive | |
| US8061273B2 (en) | Tubular signal transmission device and method of manufacture | |
| CA1069312A (en) | Blasting composition containing calcium nitrate and sulfur | |
| US3784421A (en) | Slurry explosives cross-linked with a compound of tellurium vi | |
| CA2240617C (en) | Cast explosive composition with microballoons | |
| US3442729A (en) | Aqueous inorganic oxidizer salt explosives and acrylamide polymers as thickener therefor | |
| US3940297A (en) | Gelled explosive composition and process | |
| AU688000B2 (en) | A fuse and a method of manufacturing it |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |