Dynamite

Diagram of dynamite.
A. Sawdust (or any other type of absorbent material) soaked in nitroglycerin.
B. Protective coating surrounding the explosive material.
C. Blasting cap.
D. Electrical cable connected to the blasting cap.

Dynamite is an explosive material based on the explosive potential of nitroglycerin, initially using diatomaceous earth (kieselgur: United States spelling; kieselguhr: UK spelling) or another absorbent substance such as sawdust as an absorbent. It was invented by Swedish chemist and engineer Alfred Nobel in Krümmel (Geesthacht, Schleswig-Holstein, Germany), and patented in 1867.

It is usually sold in the form of a stick 20 centimetres (roughly 8 inches) long and 2.5 centimetres (1 inch) in diameter, with a weight of about 1/4 kg (roughly 1/2 lb). Other sizes also exist. Dynamite is considered a high explosive, which means it detonates rather than deflagrates. While TNT is used as the standard for gauging explosive power, dynamite actually has more than 60% greater energy density than TNT.

Another form of dynamite consists of nitroglycerin dissolved in nitrocellulose and a small amount of ketone. This form of dynamite is similar to cordite, and is much safer than the simple mix of nitroglycerin and diatomaceous earth. Military dynamite achieves greater stability by avoiding nitroglycerin.[1]

Contents

Uses

Preparation of dynamite during the construction of the Douglas Dam, 1942.

Dynamite is mainly used in the mining, quarrying, and construction industries and has had historical use in warfare, but the unstable nature of nitroglycerin, especially if subjected to freezing, has rendered it obsolete for modern military use.

History

Alfred Nobel's 1864 patent application for nitroglycerin.
"Nobel's Extra Dynamite" manufactured by Nobel's old company, Nitroglycerin Aktiebolaget.

Dynamite was invented by Alfred Nobel and was the first safely manageable explosive stronger than black powder. Nobel obtained patents for his invention: in England on 7 May 1867 and in Sweden on 19 October 1867.[2] He originally sold dynamite as "Nobel's Blasting Powder". After its introduction, dynamite rapidly gained popularity as a safe alternative to gunpowder and nitroglycerin. Nobel tightly controlled the patent, and unlicensed duplicators were quickly shut down. However, a few American businessmen got around the patent by using a slightly different formula.[3]

Manufacture

An old Dynamite storage magazine at Ladyha' Colliery ruins, Ayrshire, Scotland.
Diatomaceous earth as viewed under bright field illumination on a light microscope. Diatomaceous earth is a soft, siliceous, sedimentary rock made up of the cell walls/shells of single cell diatoms and readily crumbles to a fine powder, it is extremely absorbent. This image of diatomaceous earth particles in water is at a scale of 6.236 pixels/μm, the entire image covers a region of approximately 1.13 by 0.69 mm.

Classic dynamite consists of three parts nitroglycerin, one part diatomaceous earth and a small admixture of sodium carbonate. This mixture is formed into short sticks and wrapped in paper. Nitroglycerin by itself is a very strong explosive, and in its pure form it is shock-sensitive (physical shock can cause it to explode), degrading over time to even more unstable forms. This makes it highly dangerous to transport or use in its pure form. Absorbed onto diatomaceous earth or more commonly sawdust, nitroglycerin is less shock-sensitive. Over time, the dynamite will "weep" or "sweat" its nitroglycerin, which can then pool in the bottom of the box or storage area. (For that reason, explosive manuals recommend turning boxes of dynamite in storage.) Crystals will form on the outside of the sticks. This creates a very dangerous situation. While the actual possibility of explosion without a blasting cap is minimal, old dynamite is still dangerous.

South Africa

For several decades from the 1940s, the biggest producer of dynamite in the world was the Republic of South Africa, where De Beers established a factory in 1902 at Somerset West. The explosives factory was later operated by AECI (African Explosives and Chemical Industries). The demand for the product came mainly from the country's vast gold mines, centered on the Witwatersrand. The factory at Somerset West was in operation in 1903 and by 1907 was already producing 340,000 cases (22 kilograms (50 lb) each) annually. In addition, a rival factory at Modderfontein was producing another 200,000 cases per year.[4]

One of the drawbacks of dynamite was that it was dangerous to manufacture. There were two large explosions at the Somerset West plant in the 1960s. Some workers died, but loss of life was limited by the modular design of the factory and earth works and plantations of trees that directed the blasts upwards. There were also several less notable but nonetheless still newsworthy explosions at the Modderfontein factory. Pressure from trade unions forced AECI, after 1985, to phase out production of dynamite. The factory then went on to solely supply ammonium nitrate emulsion based explosives that are far safer to manufacture.[5]

United States

Advertisement for the Aetna Explosives Company of New York.

In the United States, in 1885, chemist Russell S. Penniman invented ammonium dynamite, a form which used ammonium nitrate in addition to the more costly nitroglycerin. These dynamites were marketed with the trade name "Extra". Ammonium nitrate has 85% of the energy of "straight" nitroglycerin. Dynamite was manufactured by the E. I. du Pont de Nemours & Company, Inc. until the mid-1970s. Other U.S. dynamite makers of the era included California Powder Works in the California town (now city) of Hercules, Atlas, Trojan-US Powder, Austin, and several other smaller firms. Dynamite was eventually phased out in favor of water gel explosives, which are cheaper to manufacture and in many ways safer to handle.[6]

Difference from TNT

It is a common misconception that TNT and dynamite are the same thing, or that dynamite contains TNT.[7] Though both are high explosives, there is no other similarity between them. While dynamite is an absorbent mixture soaked in nitroglycerin, then compacted into a cylindrical shape and wrapped in paper, TNT is a specific chemical compound called 2,4,6-trinitrotoluene.

A stick of dynamite contains roughly 2.1 MJ of energy.[8] The energy density (joules/kilogram or J/kg) of dynamite is approximately 7.5 MJ/kg, compared to 4.6 MJ/kg of TNT.

See also

Patent

Metaphorical usage

Public knowledge of dynamite let to metaphoric uses, such as saying that a particular issue "is political dynamite" (for example at this link).

References

Notes

  1. ↑ Ledgard, Jared (2007), A Soldiers Handbook, Volume 1: Explosives Operations, ISBN 0615147941, http://books.google.com/books?id=U6f-Qlmm6zIC&pg=PA498&lpg=PA498&dq=Military+dynamite+TNT&source=bl&ots=8lPSEJUxeU&sig=eL5eVSNqZrtI81fjIXfu-0ckFc4&hl=en&ei=4rU6SqPBD4evtwfM4-XRDA&sa=X&oi=book_result&ct=result&resnum=5 
  2. ↑ Schück & Sohlman (1929), p. 101.
  3. ↑ US Patent 234489 issued to Morse 16 November 1880
  4. ↑ An MBendi Profile: South Africa - History of the Chemical Industry.
  5. ↑ Historical Highlights 1980's.
  6. ↑ DuPont Heritage: Explosives.
  7. ↑ http://lyricwiki.org/AC/DC:TNT
  8. ↑ Classroom Energy.

Sources

External links