Plastic and nonmetallic article shaping or treating: processes – Explosive or propellant article shaping or treating – Forming or treating particulate material
Patent
1997-08-01
1999-07-27
Nelson, Peter A.
Plastic and nonmetallic article shaping or treating: processes
Explosive or propellant article shaping or treating
Forming or treating particulate material
264 35, 86 2012, 102288, 102289, C06B 2100, C06B 4500, F42B 300
Patent
active
059285761
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to an explosive composition of the type known as a watergel or a slurry-type composition and to a process for manufacturing this explosive composition.
Watergel or slurry explosives are widely used because they perform well and are relatively safe to make, store and use. The high water content of watergel or slurry explosives has, however, necessitated that they be cartridged in plastic packaging. This has drawbacks in that it has presented difficulties inter alia with the proper loading of the explosive into boreholes.
In South African Patent Application No. 94/2573, an improved watergel or slurry explosive is described which has a sufficiently low water content that it is dry to the touch and can therefore be packaged in standard waxed paper cartridges of the type used for packing dynamite or other nitroglycerine sensitized explosives without causing the paper cartridge to disintegrate. The hydrogel explosive compositions described in South African Patent Application No. 94/2573 are capable of initiation by a number six strength detonator in small diameter cartridges and they are thus said to be "cap sensitive in small diameter" cartridges.
The cap sensitivity of an explosive composition is a measure of the reliability of detonation of the explosive composition in the field. The lower the temperature at which an explosive composition is cap sensitive, the less prone it is to transient desensitisation and the more likely it is to detonate reliably in the field. Also, the smaller the diameter of the cartridge, the more difficult it is to achieve cap sensitivity at a low temperature. A perchlorate salt or pigment aluminium is incorporated into the explosive compositions described in South African Patent Application No. 94/2573 to make them cap sensitive in small diameter at temperatures of 5.degree. C. or less as these components are known to lower the temperature at which an explosive composition is cap sensitive.
While the inclusion of a perchlorate salt or pigment aluminium in an explosive composition improves cap sensitivity of the composition and thus enhances its reliability, there are certain drawbacks to the inclusion of these components.
In certain countries, such as South Africa, perchlorate salts and pigment aluminium are expensive. Perchlorate salts are also very reactive.
Therefore, while the inclusion of a perchlorate salt enhances the cap sensitivity of a composition containing it, it also increases the frictional and impact or shock sensitivity of the composition. This makes the composition relatively less safe to make, store, transport and use. However, it has not been possible to do away with the perchlorate salt or pigment aluminium and still achieve low temperature cap sensitivity in these low water watergel compositions when packaged in small diameter.
SUMMARY OF THE INVENTION
According to the invention a watergel explosive composition is provided which contains an oxidiser salt, a sensitiser, a thickener, a crosslinking agent, a fuel and less than 8%, by mass, of the composition, of water and which is cap sensitive in packages having a diameter of about 26 mm or less at temperatures below about 5.degree. C. when detonated with a standard number six strength detonator, characterised in that it does not require a supplementary sensitiser or a perchlorate salt to achieve this cap sensitivity. The water content is preferably less than 6%, by mass, of the composition. More preferably, the water content is less than 5%, by mass, of the composition.
In the specification what is meant by a "standard number six strength detonator" is a 6D aluminium instantaneous electric detonator manufactured by AECI Explosives Limited, or in international terminology, a "standard number six strength detonator" is a detonator which has about 350 mg of PETN in the base charge.
The oxidiser salt is preferably a nitrate of ammonia or of an alkali or alkaline earth metal, or mixture of these. Although it is not necessary to include a perchlorate salt in the lo
REFERENCES:
patent: 3431155 (1969-03-01), Dunglinson et al.
patent: 3471346 (1969-10-01), Lyerly
patent: 3765964 (1973-10-01), Wade
patent: 3770522 (1973-11-01), Tomic
patent: 4207125 (1980-06-01), Grant
patent: 4380482 (1983-04-01), Sandell
patent: 4486495 (1984-12-01), Matsushita et al.
patent: 4555280 (1985-11-01), Levinthal
patent: 4585495 (1986-04-01), Honeyman et al.
Dantex Explosives (Proprietary) Limited
Nelson Peter A.
LandOfFree
Cap-sensitive watergel explosive composition production process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cap-sensitive watergel explosive composition production process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cap-sensitive watergel explosive composition production process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-875478