Water gel explosive

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Tovex, a form of water gel explosive. FredricRiceTovex.jpg
Tovex, a form of water gel explosive.

A water-gel explosive is a fuel-sensitized explosive mixture consisting of an aqueous ammonium nitrate solution that acts as the oxidizer. [1] Water gels that are cap-insensitive are referred to under United States safety regulations as blasting agents. Water gel explosives have a jelly-like consistency and come in sausage-like packing stapled shut on both sides. [2]

Contents

Water-gel explosives have almost completely displaced dynamite,[ citation needed ] becoming the most-used civil blasting agents.

Composition

Water gels usually have many different ingredients. They contain a gelatinizing agent, also known as a thickener, that modifies their consistency, ranging from easily pourable gels to hard solids. Polyvinyl alcohol, guar gum, dextran gums, and urea-formaldehyde resins are the typical gelling agents. Guar, specifically, is a gelling agent used for the aqueous portion of the water gel explosives. [3] The primary component of water gels is methylamine nitrate. Methylamine nitrate is the salt formed by the neutralization of methylamine with nitric acid. [4] Water gel explosives are also made of ammonium nitrate, calcium nitrate, aluminum, ethylene glycol and TNT. The proportions of these components vary depending on the desired explosiveness of the water gel. [5]

Preparation

Water gel explosives are produced by combining nitroparaffins, usually nitromethane, with an aqueous salt solution and a gelling agent. These nitroparaffins typically make up most of the water gel explosive. Different types of gelling agents are used to create the water gel explosive. One agent is insoluble in water, but able to gel with nitromethane. The gel used for nitromethane is cyanoethylether, a derivative of galactomannan gum. Other agents are water-soluble and are used for the aqueous salt solution. As mentioned above, water-soluble gums and gel modifiers (like guar) can be used for the gelling of aqueous solutions. When the salt solution and nitroparaffin are gelled, the entire mixture is combined and mixed together until the desired consistency is achieved. One characteristic that allows the explosive to work so well is the insoluble nature of the nitroparaffin. The effectiveness of the water gels is dependent on the dissemination of salts in the salt solution. The particles need to be very small and fine so that they can be dispersed well throughout the solution. Some salts that are commonly used include: ammonium nitrate, sodium nitrate, sodium perchlorate and potassium chlorate. The sensitivity of the explosive must be increased in order to improve the initiation of the detonation of the explosive. There are different techniques for increasing the sensitivity. Aluminum or other powdered metals can help increase the sensitivity of the water gel, but increasing the sensitivity also means that the explosives are more combustible. [6] Powdered metals have not proven to be completely effective in increasing the sensitivity of the explosive because they do not uniformly mix through the solution. They also lose sensitivity as storage time increases. Liquid non-self-explosive sensitizers like nitrobenzene and liquid nitrotoluene have not worked well either because they are difficult to hold in suspension. Liquid aliphatic mononitrates have been found to work very effectively as sensitizers when they are well mixed in the water gel. [7]

Advantages and uses

Water gel explosives tend to be less toxic and are less hazardous than dynamite to manufacture, transport, and store. [8] Water gels are also less expensive than conventional explosives. Because they are relatively safe and easy to use, they are often used in the mining industry. [9] There are many different types of water gel explosives for use in different situations. One type, a small diameter slurry explosive, can be used specifically for blasting in coal undercut, midcut, and depillaring areas. They are preferable to nitroglycerin-based explosives like dynamite because they produce less noxious fumes. [10] Detagel, which is very high in strength, is a specific example of a small diameter water gel explosive that is used for mining activities.[ citation needed ]

Water gel explosives are frequently used as cartridge explosives because they are much easier to load into large casings. With water gel explosives, the slurry material can simply be poured into the casing. Traditional explosives are cast into the casing. This process is laborious and the charge may begin to shrink, creating multiple voids.[ citation needed ] A final advantage of slurry is that it can be stored in non-explosive component form and sensitized into field-manufactured explosive as it is needed. The explosive may be sensitized by the addition of gas, metal powder, or another explosive such as TNT, RDX, HMX, or PETN. The water in water gel explosives is converted into a reactant by the addition of large amounts of aluminum.

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<span class="mw-page-title-main">Nitroglycerin</span> Chemical compound

Nitroglycerin (NG), also known as trinitroglycerol (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless or pale yellow, oily, explosive liquid most commonly produced by nitrating glycerol with white fuming nitric acid under conditions appropriate to the formation of the nitric acid ester. Chemically, the substance is an organic nitrate compound rather than a nitro compound, but the traditional name is retained. Discovered in 1846 by Ascanio Sobrero, nitroglycerin has been used as an active ingredient in the manufacture of explosives, namely dynamite, and as such it is employed in the construction, demolition, and mining industries. It is combined with nitrocellulose to form double-based smokeless powder, used as a propellant in artillery and firearms since the 1880s.

<span class="mw-page-title-main">Guar</span> Species of flowering plant in the bean family Fabaceae

The guar or cluster bean, with the botanical name Cyamopsis tetragonoloba, is an annual legume and the source of guar gum. It is also known as gavar, gawar, or guvar bean. The genus name Cyamopsis means bean-like. The specific name is from Latin: tetragōnoloba meaning four-lobed.

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Guar gum, also called guaran, is a galactomannan polysaccharide extracted from guar beans that has thickening and stabilizing properties useful in food, feed, and industrial applications. The guar seeds are mechanically dehusked, hydrated, milled and screened according to application. It is typically produced as a free-flowing, off-white powder.

<span class="mw-page-title-main">Ammonium nitrate</span> Chemical compound with formula NH4NO3

Ammonium nitrate is a chemical compound with the formula NH4NO3. It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is predominantly used in agriculture as a high-nitrogen fertilizer.

<span class="mw-page-title-main">ANFO</span> Explosive

ANFO ( AN-foh) (or AN/FO, for ammonium nitrate/fuel oil) is a widely used bulk industrial high explosive. It consists of 94% porous prilled ammonium nitrate (NH4NO3) (AN), which acts as the oxidizing agent and absorbent for the fuel, and 6% number 2 fuel oil (FO). The use of ANFO originated in the 1950s.

Nitromethane, sometimes shortened to simply "nitro", is an organic compound with the chemical formula CH
3NO
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Copper(II) nitrate describes any member of the family of inorganic compounds with the formula Cu(NO3)2(H2O)x. The hydrates are blue solids. Anhydrous copper nitrate forms blue-green crystals and sublimes in a vacuum at 150-200 °C. Common hydrates are the hemipentahydrate and trihydrate.

<span class="mw-page-title-main">Ammonium sulfate</span> Chemical compound

Ammonium sulfate (American English and international scientific usage; ammonium sulphate in British English); (NH4)2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen and 24% sulfur.

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<span class="mw-page-title-main">Tovex</span> Water-gel explosive

Tovex is a water-gel explosive composed of ammonium nitrate and methylammonium nitrate that has several advantages over traditional dynamite, including lower toxicity and safer manufacture, transport, and storage. It has thus almost entirely replaced dynamite. There are numerous versions ranging from shearing charges to aluminized common blasting agents. Tovex is used by 80% of international oil companies for seismic exploration.

<span class="mw-page-title-main">Urea nitrate</span> Chemical compound

Urea nitrate is a fertilizer-based high explosive that has been used in improvised explosive devices in Afghanistan, Pakistan, Iraq, and various terrorist acts elsewhere in the world such as in the 1993 World Trade Center bombings. It has a destructive power similar to better-known ammonium nitrate explosives, with a velocity of detonation between 3,400 m/s (11,155 ft/s) and 4,700 m/s (15,420 ft/s). It has chemical formula of CH5N3O4 or (NH2)2COHNO3.

<span class="mw-page-title-main">Methylammonium nitrate</span> Chemical compound

Methylammonium nitrate is an explosive chemical with the molecular formula CH6N2O3, alternately CH3NH3+NO3−. It is the salt formed by the neutralization of methylamine with nitric acid. This substance is also known as methylamine nitrate and monomethylamine nitrate, not to be confused with methyl nitramine or monomethyl nitramine.

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<span class="mw-page-title-main">Nickel hydrazine nitrate</span> Chemical compound

Nickel hydrazine nitrate (NHN), (chemical formula: [Ni(N2H4)3](NO3)2 is an energetic material having explosive properties in between that of primary explosive and a secondary explosive. It is a salt of a coordination compound of nickel with a reaction equation of 3N2H4·H2O + Ni(NO3)2 →〔Ni(N2H4)3〕(NO3)2 ＋ 3H2O

References

  1. ↑ Cook, Melvin A. The Science of Industrial Explosives. (c)1974, page 14.
  2. ↑ "Securesearch Inc - Realistic Inert Explosives Products, Inert IED Training Aids, Exact Replica Ordnances, Anti-Terrorism Awareness Products, IED Posters, Anti-Personnel Mines and Bomb Training Products for Military, Law Enforcement and Security Agencies :: Water Gel Explosives—Inert Simulants".
  3. ↑ "WATER GEL EXPLOSIVE (EDUCATIONAL)". www.freewebs.com. Archived from the original on 2014-03-11.
  4. ↑ "Water Gel Explosives". Archived from the original on 2013-04-09. Retrieved 2013-04-20.
  5. ↑ "Chemistry". 18 December 2007.
  6. ↑ "WATER GEL EXPLOSIVE (EDUCATIONAL)". www.freewebs.com. Archived from the original on 2014-03-11.
  7. ↑ http://www.skk-banjaluckapivara.com/invent/stationary_exercise_bicycle/slurry_explosive_composition.html [ dead link ]
  8. ↑ Explomo Tovex Brochure
  9. ↑ "Water Gel Explosives". Archived from the original on 2013-04-09. Retrieved 2013-04-20.
  10. ↑ "Toxic Fume Comparison of a Few Explosives Used in Trench Blasting" (PDF). www.cdc.gov. Retrieved 2018-12-08.
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