US2783712A - Re-utilisable blasting apparatus assembly applicable for blasting in coal mines - Google Patents

Re-utilisable blasting apparatus assembly applicable for blasting in coal mines Download PDF

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Publication number
US2783712A
US2783712A US352641A US35264153A US2783712A US 2783712 A US2783712 A US 2783712A US 352641 A US352641 A US 352641A US 35264153 A US35264153 A US 35264153A US 2783712 A US2783712 A US 2783712A
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United States
Prior art keywords
blasting
charge
container
threaded
disc
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Expired - Lifetime
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US352641A
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English (en)
Inventor
Kenneth A Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
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Publication date
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
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Publication of US2783712A publication Critical patent/US2783712A/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B3/00—Blasting cartridges, i.e. case and explosive
    • F42B3/04—Blasting cartridges, i.e. case and explosive for producing gas under pressure
    • F42B3/06—Blasting cartridges, i.e. case and explosive for producing gas under pressure with re-utilisable case

Definitions

  • the present invention relates to an improvement in a blasting assembly of the kind comprising apparatus of the kind comprising a pressure resisting charge container portion of tubular metal construction threaded at least at the discharge end, an internally threaded discharge head threaded at one end to engage with the threaded discharge end of said container and an expendable bursting disc adapted to yield at a predetermined pressure seated between the discharge head and the discharge end of said container so as to form a gas-tight seal, a gasgenerating charge of solid material capable when locally heated to the temperature of decomposition of a selfsupporting exothermic gas-generating decomposition in non-detonating manner under rising pressure conditions, and an electrically actuable local heating element for initiating, when itself actuated, the decomposition of said charge.
  • the blasting effect is produced by the discharge of the gases into the borehole through ports or the like in the discharge head when the pressure within the container has built up sufficiently to cause the bursting disc to yield and a passage has been opened up between the container and the discharge head.
  • the time taken for the discharge of the gases from the container into the discharge head and through the ports into the borehole after the yielding of the bursting disc is suflicient to result in a comparatively gentle heaving blasting effect, such as is desirable for such purposes as the production of lump coal.
  • the present invention also relates to blasting apparatus of readily assembled construction and of the kind comprising a pressure resisting charge container portion of tubular metal construction threaded at least at the discharge end, an internally threaded discharge head threaded at one end to engage with the threaded discharge end of said container and an expendable bursting disc adapted to yield at a predetermined pressure seated between the discharge head and the discharge end of said container so as to form a gas-tight seal.
  • the present invention also relates to an assembly comprising an electrically actuable heating element and a bursting disc as aforesaid.
  • both of the electrical connections to the local heating element have hitherto been provided on the threaded closure member of the container at the end remote from the discharge head, so that in assembling the device with its charge each time it was to be used, it was necessary to screw up the threaded joints at both ends of the tubular container, the heating element having previously been attached to the electrical connections provided on said closure member and the charge having been introduced, usually from the discharge head end of the container before the bursting disc has been placed in position and the joint with the discharge head has been screwed up. This circumstance was not conducive to rapidity of reloading,
  • the object of the present invention is to provide a blasting apparatus and a blasting assembly of the kind described adapted to be more expeditiously reloaded with a charge of a solid composition capable on local heating of supporting its own decomposition without flame, and which are free from the hazard aforementioned.
  • a blasting assembly of readily assembled construct-ion comprising apparatus of the kindcomprising a pressure resisting charge container portion of tubular metal construction threaded at least at the discharge end, an internally threaded discharge head threaded at one end to engage with the threaded discharge end of said container and an expendable bursting disc adapted to yield at a predetermined pressure seated between the discharge head and the discharge end of said container so as to form a gas-tight seal, a gas-generating charge of solid material capable when locally heated to the temperature of decomposition of a self-supporting exothermic gas-generating decomposition in non-detonating manner under pressure rising conditions, and an electrically actuable local heating element for initiating, when itself actuated, the decomposition of said charge, is characterised in that at least one of the two electrical lead Wires of said electrically actuable local heating element is insulated and passes through the bursting disc forming with it an insulated gas tight seal and a free end at least of a length to permit it
  • a threaded closure member is provided to engage with said non-discharge end.
  • the bore of the container portion at the bursting disc end is suflicient to enable the charge of the gas-producing composition to be introduced in pre-packed form, which has not hitherto been possible since hitherto the bore at both ends of. the container portion has beenv greatly reduced.
  • the bursting disc which is preferably of. steel, is. provided with a hole, preferably through its, centre, and has attached firmly on one side of it a metal sleeve whose bore is in line with said hole so as to permit at least one insulated electrical lead wire to pass through said hole and boring and to be fixed in said sleeve by a plug of sealing material. If desired one of the insulated electrical conductors may be connected to the sleeve itself, as it will be understood that the sleeve is in electrical connection through the disc with the metal body of the blasting apparatus.
  • the present invention also includes a blasting apparatus of readily assembled construction and of the kind comprising a pressure resisting charge container portion of tubular metal construction threaded at least at the discharge end, an internally threaded discharge head threaded at one end to engage with the threaded discharge end of said container and an expendable bursting disc adapted to yield at a predetermined pressure seated between the discharge head and the discharge end of said container so as to form a gas-tight seal characterised in that said bursting disc has at least one insulated electrical lead Wire of an electrically actuable local heating element passing through it and forming with it an insulated gas tight seal and a free end at least of a length to permit it to be passed through the wall of the discharge head.
  • a thread closure member is provided to engage with said non-discharge end.
  • the bore of the container portion at the bursting disc end is sufficient to enable a charge of gas producing composition to be introduced in pro-packed form.
  • the bursting disc should prefen ably be of steel, should be provided with a hole preferably through its centre, and should have attached firmly on one side a metal sleeve whose bore is in line with said hole so as to permit at least one insulated electrical lead wire to pass through said hole and bore and to be fixed in said sleeve by a plug of sealing material.
  • the present invention also includes an assembly comprising an electrically actuable heating element wherein at least one of its two electrical lead wires is insulated and passes through a bursting disc forming with it an insulated gas-tight seal and a free end.
  • Fig. 1 represents a longitudinal section of a blast-' ing apparatus in accordance with the invention shown with the gas producing charge and heating element in position and assembled ready for the blast.
  • Fig. 2 is a detail of a portion of the expendablepart of. the. apparatus somewhat'difierent inform fromnthatiillustratedin Fig. 1.
  • the tubular container portion of the apparatus 1 is of high tensile steel and its external surface is threaded for some distance at each end, the actual end surfaces being accurately faced.
  • the bore of this portion is cylindrical for the greater part of its length but is somewhat diminished at one end.
  • the steel closure cup 2 is internally threaded for some distance from its open end as shown at 3, and has a reduced thickness of metal extending beyond the closed cup recess pierced by an eye 4. through the reduced thickness of the metal.
  • This eye serves to facilitate the withdrawal of the assembly from the debris after firing, and also providesmeans whereby an earth wire 5 may be expeditiously connected to the blasting assembly from without.
  • 6 is a soft copper gasket seated in the recess of the closure cup 2' so that when the faced narrower end surface of the container portion 1. isxbrought to bear upon it by screwing up the threads 3 a gas-tight sealed joint is formed.
  • 7 is a cylindrical packet containing a charge of a pulverulent composition consisting of 53% to 57% sodium nitrite, 41% to- 44% ammonium chloride and 1% to 3% magnesium oxide, into one end of which there is a recess, the recessed end of the packet facing the discharge end of the assembly.
  • Thepurpose of this recess is to accommodate the ventless electrically actuated local heater 3, which has a copper easing into which there is compressed a heating charge 11 consisting of a mixture of antimony and potassium permanganate.
  • the mouth of the casing of the heater is crimped around a plug of a polymerised chloroprenc composition through which pass insulated conductors 9 and 9 leading to an electric matchhead 10, positioned so that the deflagration of the matchhead composition will initiate the strongly exothermic reaction between the antimony and the potassium permanganate in said mixture.
  • the heat conducted through the copper casing initiates the decomposition of the sodium nitrite-ammonium chloride-magnesium oxide mixture in the recessed portion of the local heater 8, and the decomposition is thereafter rapidly transmitted through the whole of the charge in the packet 7.
  • 12 is a steel venting head in the form of an elongated cup having an internally threaded shouldered counter-bore, the shoulder being cut accurately to form a seating for a steel disc 14 adapted to burst at a predetermined pressure sufficient to produce a blasting effect.
  • This bursting disc14' has a small central perforation drilled through it, and on one side of the disc there is welded co-axially positioned a copper sleeve 15 into the open end of which there is forced a tube made of a polymerised chloroprene composition 16 through which there pass the insulated conductors 9 and 9' from the ventless' electric local heating element 8.
  • One of the conductors 9 facing the plug 16 is bared at its end and soldered or brazed to the sleeve 15, the other conductor passing through the central hole in the disc 14 and outwardly through a small boring 18 in the end wall of the dis-charge head to the live terminal of a firing switch connected to a battery some distance from the scene of the blast.
  • 17 is an annular soft rubber gasket bonded to that surface of the disc 14' hearing the sleeve 15, this gasket 17 assisting the operator to make as gas-tight a joint as possible when the threads of the discharge head 12 are screwed up over those on the exterior surface of the container portion 1.
  • the discharge ports 13 from the interior to the exterior of the discharge head 12 are inclined at such an angle that the reaction to the escape of gas from the interior of the discharge head is away from the threaded end thereof towards the end closed but for the boring 18. It will be understood it is the discharge head end of the assembly that is inserted first into the borehole.
  • the weight of the charge in the packet 7 is sufficient to generate a ga pressure exceeding the pressure at which thedisc 14 will burst.
  • the closure member is pref-- erably firstoscrewed. home against the gasket 6 so-that the closure at the narrower end of the container portion 1 is already gas-tight before it comes to the hands of the shotlayer, who also receives in a completed state an assembly of the bursting disc 14 carrying the sleeve 15 and gasket 16 with the conductors 9 and 9' and the electric local heater 8 attached to it, the greater part of the length of the insulated conductor 9 beyond the plain surface of the disc being coiled up for convenience.
  • the shotfirer first makes a recess in one end of the package containing the charge 7 and inserts local heater 8 into the recess.
  • Fig. 2 the numerals 9, 9, 14, 15 and 17 have the same significance as in Fig. 1, but the polymerised chloroprene composition plug 16 is replaced by a plug of fusible metal 1? poured through the open end of the sleeve.
  • a blasting assembly for use in a reutilisable blasting device comprising a pressure resisting charge container of tubular construction sealed at one end, and a discharge head removably engaged on the other end of said container, said blasting assembly comprising an expendable bursting disc having its peripheral portion sealingly engaged between said discharge head and the discharge end of said container, said disc having an opening therein, a sleeve secured to said disc in surrounding relation to said disc opening, a gas generating charge capable of self-sustained fiameless exothermic decomposition when locally heated, and an electrically actuable heating element, said heating element being arranged in said container with said gas generating charge in a prepackaged form and having electrical lead wires for actuation thereof, at least one of said electrical wires being insulated and passing through the disc opening and said sleeve, and a plug being arranged in said sleeve and cooperating therewith to effect a gas tight seal around the electrical Wire passing through said sleeve.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Resistance Heating (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)
  • Disintegrating Or Milling (AREA)
US352641A 1952-06-23 1953-05-04 Re-utilisable blasting apparatus assembly applicable for blasting in coal mines Expired - Lifetime US2783712A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB15739/52A GB732363A (en) 1952-06-23 1952-06-23 An improvement in or relating to a re-utilisable blasting apparatus assembly applicable for blasting in coalmines

Publications (1)

Publication Number Publication Date
US2783712A true US2783712A (en) 1957-03-05

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Application Number Title Priority Date Filing Date
US352641A Expired - Lifetime US2783712A (en) 1952-06-23 1953-05-04 Re-utilisable blasting apparatus assembly applicable for blasting in coal mines

Country Status (5)

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US (1) US2783712A (da)
BE (1) BE520882A (da)
DE (1) DE942012C (da)
FR (1) FR1080935A (da)
GB (1) GB732363A (da)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2924147A (en) * 1957-08-05 1960-02-09 Leland S Bohl Blast-free explosive line cutter
US3261163A (en) * 1961-06-19 1966-07-19 Aerojet General Co Rocket motor testing apparatus
CN116398679A (zh) * 2023-04-23 2023-07-07 江苏民诺特种设备有限公司 一种泄压阀及带有该泄压阀的钢瓶

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1632887A (en) * 1924-05-03 1927-06-21 Safety Pressure Mining & Equip Blasting cartridge
US2207191A (en) * 1937-12-27 1940-07-09 Cardox Corp Apparatus for blasting coal

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1632887A (en) * 1924-05-03 1927-06-21 Safety Pressure Mining & Equip Blasting cartridge
US2207191A (en) * 1937-12-27 1940-07-09 Cardox Corp Apparatus for blasting coal

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2924147A (en) * 1957-08-05 1960-02-09 Leland S Bohl Blast-free explosive line cutter
US3261163A (en) * 1961-06-19 1966-07-19 Aerojet General Co Rocket motor testing apparatus
CN116398679A (zh) * 2023-04-23 2023-07-07 江苏民诺特种设备有限公司 一种泄压阀及带有该泄压阀的钢瓶

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Publication number Publication date
GB732363A (en) 1955-06-22
DE942012C (de) 1956-04-26
FR1080935A (fr) 1954-12-14
BE520882A (da)

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