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US3713384A - Blasting method - Google Patents

Blasting method Download PDF

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Publication number
US3713384A
US3713384A US00021904A US3713384DA US3713384A US 3713384 A US3713384 A US 3713384A US 00021904 A US00021904 A US 00021904A US 3713384D A US3713384D A US 3713384DA US 3713384 A US3713384 A US 3713384A
Authority
US
United States
Prior art keywords
downline
detonating cord
primer
connecting length
primer assembly
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 - Lifetime
Application number
US00021904A
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English (en)
Inventor
B Turnbull
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
Original Assignee
Imperial Chemical Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
Application granted granted Critical
Publication of US3713384A publication Critical patent/US3713384A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/04—Arrangements for ignition

Definitions

  • ABSTRACT A blasting method and primer assembly for blasting agents wherein the primer assembly comprises a high explosive priming charge, a connector and an intermediate length of detonating cord, the connector being adapted to hold the detonating cord in close lengthwise proximity to and slidably movable along a downline of detonating cord.
  • This invention relates to blasting and to a primer assembly for initiating blasting explosives of low sensitivity in blasting.
  • blasting agent is applied to an explosive composition which is insensitive to initiating by a No. 6 detonator (base charge 0.24 g. PETN) and hereinafter refers to such an explosive composition.
  • Blasting agents include compositions containing no self-explosive ingredient and which on the North American continent are classified as NCN (nitrocarbonitrate) explosives, together with other explosives containing self-explosive ingredients (such as slurry explosives containing TNT), provided that the final product is not sensitive to initiation by a No. 6 detonator.
  • NCN nitrogenitrate
  • the primer may be a cartridge of a nitroglycerine gelatine explosive such as Polar Ammon. Gelatine Dynamite or Opencast Gelignite, or alternatively it may be cast or pressed Pentolite primer. It has been found that, generally, an explosive of very high velocity of detonation, such as cast Pentolite primer, is the most effective initiator for blasting agents, and that detonation of the blasting agent is effected by a smaller weight of pentolite if the primer is an elongated primer initiated at one end.
  • each primer being placed in position as the blasting agent is loaded.
  • the primers are initiated by means of detonating cord leading from a detonator outside the shothole.
  • each primer may be provided with a downline of detonating cord but it is obviously more economical to employ a single downline with the primers threaded thereon.
  • a cast primer having a passage cast therein to permit the primer to be threaded on the downline and to be pushed down the line into the shothole must be used, and, because some clearance between the primer and detonating cord is necessary, the desired initiation of the primer from the detonating cord does not always occur.
  • a method of blasting in accordance with the invention comprises positioning a downline of detonating cord in a shothole, loading a blasting agent as hereinbefore defined into the shothole, and, at selected stages of the loading, slidably connecting to the downline in detonation transmission relationship a high explosive primer and an intermediate connecting length of detonating cord, by connecting means which holds an end portion of the said intermediate length of detonating cord in close lengthwise proximity to the downline while permitting it to be slidably moved along the downline, and moving the primer into the desired position in the shothole.
  • the invention also includes a primer assembly for initiating a blasting agent which comprises a priming charge of high explosive, a connecting length of detonating cord attached at one end in detonation transmission relationship to the said explosive charge, and a connector attached to the other end of the length of detonating cord, the said connector being adapted to hold the detonating cord in close lengthwise proximity to a downline of detonating cord while permitting it to be slidably moved along the said downline.
  • a primer assembly for initiating a blasting agent which comprises a priming charge of high explosive, a connecting length of detonating cord attached at one end in detonation transmission relationship to the said explosive charge, and a connector attached to the other end of the length of detonating cord, the said connector being adapted to hold the detonating cord in close lengthwise proximity to a downline of detonating cord while permitting it to be slidably moved along the said downline.
  • One end of the connecting length of detonating cord is preferably immersed in the priming charge and, when the priming charge is a castable explosive, for example TNT or Pentolite (TNT/PETN), the priming charge may conveniently be cast around the detonating cord.
  • a castable explosive for example TNT or Pentolite (TNT/PETN)
  • TNT/PETN Pentolite
  • the end of the detonating cord intended for connection to the downline is preferably covered by a waterproofing composition, for example silicone rubber and/or a metal end-cap.
  • the preferred primer has a length to maximum crosssectional dimension ratio of not less than 3:1 and preferably greater than 5:1 and the connecting length of detonating cord is preferably attached near to one end of the primer.
  • the primer may conveniently be circular or rectangular but other cross-sectional shapes may be used. It will be understood that the primer may consist of several smaller charges placed in end-to-end contact.
  • FIG. 1 shows diagrammatically a perspective view of a primer assembly of the invention connected to a downline of detonating cord;
  • FIG. 2 shows a section of the connector shown in FIG. 1 on the line Il-II of FIG. 1;
  • FIG. 3 shows diagrammatically the disposition of primer assemblies as shown in FIG. 1 in a shothole.
  • a priming explosive composition 11 is cast in a polyethylene container 12 around the knotted end of a connecting length of detonating cord 13, the container being closed by a lid 14.
  • the other end of cord 13 is threaded as a sliding fit through a bore 15 in a polyethylene connector 16, doubled back and threaded through a bore 17 in connector 16 and is covered by a silicone waterproofing composition 18 (Silcoset, Registered Trade Mark, RTV rubber) and a tubular aluminum end-cap 19.
  • the connector 16 has a bore 20 which overlaps bore 17 and in use the connector 16 is sleeved on a downline 21 of detonating cord by threading the downline through bore 20.
  • a downline 21 having a priming composition 11 in a container 12 is lowered down a shothole 22, as shown in FIG. 3.
  • Blasting agent 23 is loaded into the shothole 22 up to the level a.
  • the connector 16 of a primer assembly as shown in FIG. 1 is sleeved on downline 21 and the assembly is allowed to slide down the shothole to level a.
  • the loading of blasting agent is continued until the shothole is filled to level b, when a further primer assembly is connected to the downline 21 and allowed to slide down the shothole to level b.
  • Charging of blasting agent and primers is continued in this manner until the shothole is charged to the desired level.
  • the top portion of the shothole is then filled with stemming material 24 and the explosive is detonated by means of a detonator 25 connected to the downline 21.
  • a primer assembly for initiating a blasting agent which comprises a priming charge of high explosive, a connecting length of detonating cord attached at one end in detonation transmission relationship to the said explosive charge, and a connector attached to the other end of said connecting length for slidably connecting the assembly of priming charge and connecting length to a downline of detonating cord, said connector comprising a body member having bore means therethrough which surround a portion of said connecting length, the bore means having a longitudinal wall portion adapted to slidably engage a downline of detonating cord when the latter is inserted through said bore means and said bore means having a further longitudinal wall portion firmly holding said connecting length and positioning the same in parallel detonating relationship with the downline when the latter has been inserted through the bore means.
  • a primer assembly as claimed in claim 1 wherein the priming composition comprises cast or pressed Pentolite consisting of PETN and TNT in a ratio of 40:60 to 60:40 by weight tetryl, cyclotrimethylenetrinitramine or mixtures of cyclotrimethyIenetrinitramine and TNT.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Drilling And Exploitation, And Mining Machines And Methods (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)
  • Connections Effected By Soldering, Adhesion, Or Permanent Deformation (AREA)
  • Manufacturing Of Electrical Connectors (AREA)
  • Air Bags (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
US00021904A 1969-03-31 1970-03-23 Blasting method Expired - Lifetime US3713384A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1661569 1969-03-31

Publications (1)

Publication Number Publication Date
US3713384A true US3713384A (en) 1973-01-30

Family

ID=10080517

Family Applications (1)

Application Number Title Priority Date Filing Date
US00021904A Expired - Lifetime US3713384A (en) 1969-03-31 1970-03-23 Blasting method

Country Status (7)

Country Link
US (1) US3713384A (fi)
CA (1) CA932583A (fi)
DE (1) DE2015286C3 (fi)
FR (1) FR2036008B1 (fi)
GB (1) GB1233138A (fi)
NO (1) NO121589B (fi)
OA (1) OA03245A (fi)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3878785A (en) * 1971-12-01 1975-04-22 Nitro Nobel Ab Propagation device and initiation system for low energy fuses
US3880080A (en) * 1973-04-06 1975-04-29 Ireco Chemicals Booster for explosive blasting agents
US4098189A (en) * 1976-09-28 1978-07-04 Harry Holm Method and apparatus for preparing an explosive charge
US4133247A (en) * 1976-11-11 1979-01-09 Austin Powder Company Carrier for explosive primer and method of using same
US4141296A (en) * 1976-11-11 1979-02-27 Austin Powder Company Carrier for explosive primer and method of using same
USRE30621E (en) * 1980-04-16 1981-05-26 Austin Powder Company Carrier for explosive primer and method of using same
USRE31953E (en) * 1976-11-11 1985-07-23 Austin Powder Company Method of charging a borehole
US4714018A (en) * 1985-07-01 1987-12-22 Nitro Nobel Ab Method and means for connecting fuses
US4716832A (en) * 1986-09-18 1988-01-05 Halliburton Company High temperature high pressure detonator
US4821645A (en) * 1987-07-13 1989-04-18 Atlas Powder Company Multi-directional signal transmission in a blast initiation system
US4953464A (en) * 1987-07-13 1990-09-04 Atlas Powder Company Multi-directional signal transmission in a blast initiation system
US5069135A (en) * 1988-12-08 1991-12-03 Aktiebolaget Bofors Ignition system
US5086702A (en) * 1990-04-12 1992-02-11 Atlas Powder Company Modular blasting system
US5162606A (en) * 1990-04-12 1992-11-10 Atlas Powder Company Modular blasting system
US5171935A (en) * 1992-11-05 1992-12-15 The Ensign-Bickford Company Low-energy blasting initiation system method and surface connection thereof
US5204492A (en) * 1991-10-30 1993-04-20 Ici Explosives Usa Inc. Low noise, low shrapnel detonator assembly for initiating signal transmission lines
US5398611A (en) * 1990-11-05 1995-03-21 The Ensign-Bickford Company Low energy blasting initiation system, method and surface connection therefor
WO1999053264A1 (en) * 1998-04-09 1999-10-21 Ensign-Bickford (South Africa) (Proprietary) Limited Explosives booster
WO2002037050A1 (en) * 2000-11-02 2002-05-10 Zaklady Tworzyw Sztucznych Nitron S.A. Detonating cord-booster

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3878785A (en) * 1971-12-01 1975-04-22 Nitro Nobel Ab Propagation device and initiation system for low energy fuses
US3880080A (en) * 1973-04-06 1975-04-29 Ireco Chemicals Booster for explosive blasting agents
US4098189A (en) * 1976-09-28 1978-07-04 Harry Holm Method and apparatus for preparing an explosive charge
US4133247A (en) * 1976-11-11 1979-01-09 Austin Powder Company Carrier for explosive primer and method of using same
US4141296A (en) * 1976-11-11 1979-02-27 Austin Powder Company Carrier for explosive primer and method of using same
USRE31953E (en) * 1976-11-11 1985-07-23 Austin Powder Company Method of charging a borehole
USRE30621E (en) * 1980-04-16 1981-05-26 Austin Powder Company Carrier for explosive primer and method of using same
US4714018A (en) * 1985-07-01 1987-12-22 Nitro Nobel Ab Method and means for connecting fuses
US4716832A (en) * 1986-09-18 1988-01-05 Halliburton Company High temperature high pressure detonator
US4953464A (en) * 1987-07-13 1990-09-04 Atlas Powder Company Multi-directional signal transmission in a blast initiation system
US4821645A (en) * 1987-07-13 1989-04-18 Atlas Powder Company Multi-directional signal transmission in a blast initiation system
US5069135A (en) * 1988-12-08 1991-12-03 Aktiebolaget Bofors Ignition system
US5086702A (en) * 1990-04-12 1992-02-11 Atlas Powder Company Modular blasting system
US5162606A (en) * 1990-04-12 1992-11-10 Atlas Powder Company Modular blasting system
US5398611A (en) * 1990-11-05 1995-03-21 The Ensign-Bickford Company Low energy blasting initiation system, method and surface connection therefor
US5204492A (en) * 1991-10-30 1993-04-20 Ici Explosives Usa Inc. Low noise, low shrapnel detonator assembly for initiating signal transmission lines
US6123025A (en) * 1991-10-30 2000-09-26 Orica Explosives Technology Pty Ltd. Low noise, low shrapnel detonator assembly for initiating signal transmission lines
US5171935A (en) * 1992-11-05 1992-12-15 The Ensign-Bickford Company Low-energy blasting initiation system method and surface connection thereof
WO1999053264A1 (en) * 1998-04-09 1999-10-21 Ensign-Bickford (South Africa) (Proprietary) Limited Explosives booster
US6186069B1 (en) 1998-04-09 2001-02-13 Ensign-Bickford (South Africa Proprietary) Limited Explosives booster
WO2002037050A1 (en) * 2000-11-02 2002-05-10 Zaklady Tworzyw Sztucznych Nitron S.A. Detonating cord-booster

Also Published As

Publication number Publication date
FR2036008A1 (fi) 1970-12-24
DE2015286A1 (de) 1971-01-28
NO121589B (fi) 1971-03-15
DE2015286C3 (de) 1973-01-04
OA03245A (fr) 1970-12-15
CA932583A (en) 1973-08-28
FR2036008B1 (fi) 1976-01-16
GB1233138A (fi) 1971-05-26

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