Water gel explosive

Rhenium Diboride

Nitrobenzene-balls

FredricRiceTovex

A water-gel explosive or or a slurry is a fuel sensitized explosive mixture consisting of an aqueous ammonium nitrate solution that acts as the oxidizer. Water gels that are cap-insensitive are not strictly explosives and are referred to as blasting agents. Water gel explosives have a jelly-like consistency and come in sausage-like packing and are stapled shut on both sides.

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, urea-formaldehyde resins are the typical gelling agents. Guar, specifically, is a gelling agent used for the aqueous portion of the water gel explosives. The primary component of water gels is monomethylamine nitrate. Monomethylamine nitrate is made of methyl methacrylate or MMA, formaldehyde and ammonium nitrate. 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.

How the Gel is Made

The water gel is made by combining nitro paraffin, usually nitromethane (which can be toxic if inhaled), with an aqueous salt solution. Nitro paraffins usually make up most of the water gel explosive. This mixing is done in the presence of a gelling agent. There are different types of gelling agents that are used to create the water gel explosive. One agent is insoluble in water, but able to gel with nitro methane.The gel used for nitro methane is cyanoethylether, a derivative of gallactomannan gum. Other agents are water soluble and are used for the aqueous salt solution. As referenced in the first paragraph, water-soluble gums and gel modifiers like guar can be used for the gelling of aqueous solutions. When the salt solution and nitro paraffin 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 nitro paraffin. 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. One way to do this is to increasing 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. 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 become lose sensitivity as storage time increases. Liquid non- self-explosive sensitizers like nitrobenzene and liquid nitroluene have not worked as 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.

Advantages and uses

They tend to be less toxic and are less hazardous than dynamite to manufacture, transport, and store. Water gels are also less expensive compared to conventional explosives. Because they are relatively safe and easy to use, they are often times used in the mining industry. There are many different types of water gel explosives and each type of explosive can be used 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 more favorable than nitroglycerin based explosives like dynamite because they produce less noxious fumes. Detagel, which is very high in strength, is a specific example of a small diameter water gel explosive that is used for mining activities.

They are frequently used as cartridge explosives because they are much easier to load into large casings. With water gel explosives, filling a bomb is merely a matter of pouring the material into the casing. Traditionally explosives are ordinarily cast into the casing. This process is laborious and the charge may begin to shrink creating multiple voids. 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 amount of aluminum. Water-gel explosives represent the majority of the blasting agents used in the commercial market and have almost completely displaced dynamite.