Ammunition and explosives – Igniting devices and systems – Holders for fuse or fuse cord to blasting cartridge,...
Patent
1997-07-18
2000-09-05
Jordan, Charles T.
Ammunition and explosives
Igniting devices and systems
Holders for fuse or fuse cord to blasting cartridge,...
102318, C06C 506
Patent
active
061126667
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an explosives primer and booster.
DESCRIPTION OF THE RELATED ART
Civilian blasting operations require detonation of explosive charges at a controlled time. In mining operations this commonly requires the detonation of a number of blastholes, each filled with a large explosive charge, the blastholes being detonated at a controlled time and in a controlled sequence. This is achieved by devices referred to as "initiating explosives" which transmit signals from one place to another using electrical or chemical (non-electric) energy. Initiation sequences can be controlled by using electrical timing systems or chemical delay elements. Initiating explosives systems incorporate various explosive and inert components which may be wholly or partly consumed in the blast.
Non-electric initiation systems utilise chemical reactions, which can range from rapid burning to violent detonation, to initiate explosive charges either directly or via non-electric detonators. Electric initiation systems require a device which can generate or store electrical energy that is transmitted to electric detonators by a circuit of insulated conductors. A combination of electric and non-electric initiating explosives can be used to initiate blasts but there is a general trend to the use of completely non-electric systems in Australian mines. Non-electric systems cause little disruption to surroundings as they function and provide a high level of safety against accidental initiation by static electricity, stray electrical currents and radio frequency energy.
One of the key components in non-electric initiating systems is non-electric tubing - plastic tubing coated on the inside with a reactive powder. Non-electric tubing or signal tube is commonly attached at one end to a non-electric detonator to form a "detonating assembly". Signal tube has the particular advantage that it cannot be initiated by flame, friction or impact normally encountered in mining operations.
Another commonly used initiating explosive device utilised in blasting is the non-electric primer. A non-electric primer is formed when the non-electric detonator of a detonator assembly is located within a booster--a body of high explosive of tremendous brisance.
In mining applications, the primer is placed in a blasthole which is then filled with packaged or bulk explosives. An initiation signal is triggered from a remote location and passes along the non-electric tubing to the detonator. A small charge of high explosive in the detonator is initiated and explodes, detonating the booster, which in turn causes the larger body of explosive in the blasthole to explode.
Examples of primer systems currently in use include those which use ANZOMEX primers in combination with PRIMADET detonators and EXEL signal tube. (ANZOMEX and EXEL are registered trade marks of ICI Australia Operations Proprietary Limited; PRIMADET is a trade mark of the Ensign Bickford Company). ANZOMEX primers consist of a cylinder of hard explosive, cast to include two passages or wells. The detonator assembly is looped through these passages.
Another related system utilises a slip on booster (SOB) from North American Explosives. (SOB is a U.S. registered trade mark of the Ensign-Bickford Company.) The booster comprises an open cup containing plasticised, soft explosive and a detonator is pressed into the soft matrix. A very similar product is the NOBEL PRIME primer. NOBEL PRIME primers contain a soft, gel-like explosive called PRIMEX, which comprises nitroglycerine
itroglycol and nitrocellulose in which pentyl and ammonium nitrate are mixed. (NOBEL PRIME and PRIMEX are registered trade marks of Dyno Wesfarmers Ltd.) The soft booster composition partly fills a cylindrical canister up to 100 millameters or more in length and a detonator is pushed through a disk which is formed by an almost complete circle of perforations in the end of the canister. The disk does not break away completely but hinges inward and partly helps to keep the detonator in place.
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Courtley Steven Richard
Murray Christopher Charles
Buckley Denise J
Jordan Charles T.
Orica Explosives Technology Pty. Ltd.
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