Tovex

Tovex (also known as Threnchrite, Seismogel, and Seismopac) is a water gel explosive that has several advantages over traditional dynamite. Tovex has almost entirely replaced dynamite. Tovex enjoys a number of advantages over nitroglycerin based dynamite in that Tovex is less toxic and is less hazardous to manufacture, transport, and store. [ [http://www.explomo.com/commer.htm Explomo Tovex Brochure] ] Tovex is used by 80% of international oil companies for seismic exploration. [ [http://www.biafo.com/profile.htm Biafo Tovex Brochure] ] There are numerous versions ranging from shearing charges to aluminized common blasting agents.

History

Tovex was developed by E. I. du Pont de Nemours & Company, Inc., DuPont in the mid-to-late 1960s when pelletized TNT was included in aqueous gels to create a slurry form of ANFO that displayed water-resistant properties in wet bore holes. TNT sensitized water gels ("Tovex") were commercially successful, yet the TNT led to problems with oxygen balance: namely elevated amounts of combustion by-products such as carbon monoxide and nitrogen-dioxide complexes. Not only was TNT "dirty," but it was also expensive. TNT was eliminated through the work of DuPont chemists Colin Dunglinson and William Lyerly and a team of others at DuPont's Potomac River Development Laboratory (PRDL) at Falling Waters, West Virginia, and at DuPont's Eastern Laboratories (EL) at Gibbstown, New Jersey. These chemists and engineers formulated a series of water gel-base products that replaced the TNT with methyl ammonium nitrate, also known as mono-methylamine nitrate, or PR-M, (which stands for "Potomac River - monomethylamine nitrate") creating the "Tovex" "Extra" product line.

In late 1973, DuPont declared "the last days of dynamite" and switched to the new Tovex. The "Tovex" (that replaced nitroglycerin-based dynamite) had evolved into a cap-sensitive product. Even though it bore the same name as the earlier "Tovex," it was quite different from the precursors which could only be initiated with a one pound TNT booster in large diameter (5-inches). The new Tovex of the mid-to-late 1970s could be detonated in (critical) diameters much smaller than 5-inches by utilizing DuPont's Detaflex, thus making the new Tovex a realistic replacement for dynamite.

Until then, only nitroglycerin based explosives were commercially feasible for blasters who wanted cap-sensitive explosives that could be initiated with a #6 blasting cap in bore holes as small as 3/4 of an inch in diameter, sometimes less. The new Tovex satisfied that requirement.

Atlas, Hercules, IRECO, Trojan-US Powder and several other explosives manufacturing firms of the era created emulsions, gels and slurries which accomplished the same end, but it was the DuPont patent of PR-M based explosives (U.S. Patent 3,431,155) that gave the DuPont Company a competitive edge.

As of this writing, explosives sold under DuPont's original "Tovex" trade name are distributed in Europe by Societe Suisse des Explosifs, Brigue, in Switzerland.

Properties

Tovex is a 50/50 aqueous solution of ammonium nitrate and methyl ammonium nitrate (sometimes also called mono methylamine nitrate, or PR-M), sensitized fuels and other ingredients including sodium nitrate prills, finely divided (paint-grade) aluminum, finely divided coal, and proprietary materials to make some grades cap sensitive, and thickening agents to enhance water resistance and that act as crystal modifiers. [ [http://www.ncjrs.gov/txtfiles1/nij/178913.txt Guide for the Selection of Commercial Explosives Detection] ] The detonation Velocity of Tovex is around 4,000 to 5,500 mps. The specific gravity is 0.8-1.4. Tovex looks like a white to black fluid gel. [ [http://www2.hazard.com/msds/f2/bnr/bnrwt.html MSDS] ]

Ingredients

*sodium nitrate
*ammonium nitrate
*methyl ammonium nitrate (sometimes called "Monomethylamine Nitrate")
*calcium nitrate
*aluminum
*fuel oil No.2
*carbonaceous Fuel
*perlite
*silica (fibrous glass)
*ethylene glycol
*guar gum

Uses

Tovex Avalanche is used in mountain regions for avalanche release.
* blasting for road construction
* mining for minerals
* quarries for the construction and building industry
* seismic exploration
* tunneling

Features

* cap sensitive
* wide range of bore hole densities
* improved flexibility in loading
* water-resistance
* no nitroglycerin and noxious fumes
* reduced handling, transportation and storage hazards
* high bubble energy (underwater explosion)
* reduced sound levels and better control on vibrations

References