Dynamite is an explosive made of nitroglycerin, sorbents (such as powdered shells or clay) and stabilizers. It was invented by the Swedish chemist and engineer Alfred Nobel in Geesthacht, and patented in 1867. It rapidly gained wide-scale use as a safer alternative to gun powder and nitroglycerin.
Invention, purpose, and use
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, in Sweden on 19 October 1867. After its introduction, dynamite rapidly gained wide-scale use as a safe alternative to black powder and nitroglycerin. Nobel tightly controlled the patents, and unlicensed duplicating companies were quickly shut down. However, a few American businessmen got around the patent by using a slightly different formula.
Nobel originally sold dynamite as "Nobel's Blasting Powder" but decided to change the name to dynamite, from the Ancient Greek word δύναμις dýnamis, meaning "power".
An industrialist, engineer, and inventor, Alfred Nobel's father, Immanuel Nobel, built bridges and buildings in Stockholm. His construction work inspired him to research new methods of blasting rock. Immanuel's work with explosives later on inspired Alfred to make explosives safer and more effective. Today dynamite is mainly used in the mining, quarrying, construction, and demolition industries. Dynamite is still the product of choice for trenching applications, and as a cost-effective alternative to cast boosters. Dynamite is occasionally used as an initiator or booster for AN and ANFO explosive charges.
Nitroglycerin by itself is a very strong explosive, but is extremely shock-sensitive (that is, physical shock can cause it to explode), and degrades over time to even more unstable forms, which makes it highly dangerous to transport or use. Dynamite combines nitroglycerin with adsorbents and stabilizers, rendering it safe to use, but retaining the powerful explosive properties of nitroglycerin.
The original composition of dynamite consisted of three parts "Explosive Oil" (nitroglycerin), one part diatomaceous earth as the absorbent, and a small admixture of sodium carbonate antacid as the stabilizer. Ethylene glycol dinitrate was later added to the nitroglycerin to lower its freezing point and keep it from freezing into a slush at low temperatures, which made it unstable, or from sweating out when it thawed. Diatomaceous earth is not usually used today as an absorbent medium and it has been replaced by cheaper media like sawdust, wood pulp, flour, or starch. Other stabilizers like calcium carbonate or zinc oxide can be used in the place of sodium carbonate. Sodium nitrate is added to the medium as an oxidizer that improves the dynamite's brisance.
Dynamite is usually sold in the form of cardboard cylinders about 20 cm (8 in) long and about 3.2 cm (1.25 in) in diameter, with a weight of about 190 grams (1⁄2 troy pound). A stick of dynamite thus produced contains roughly 1 MJ of energy. Other sizes also exist, rated by either portion (Quarter-Stick or Half-Stick) or by weight.
Dynamite is usually rated by "weight strength" (the amount of nitroglycerin it contains), usually from 20% to 60%. For example, 40% dynamite is composed of 40% nitroglycerin and 60% "dope" (the absorbent storage medium mixed with the stabilizer and any additives).
The maximum shelf life of nitroglycerin-based dynamite is recommended as one year from the date of manufacture under good storage conditions.
Over time, regardless of the sorbent used, sticks of dynamite will "weep" or "sweat" nitroglycerin, which can then pool in the bottom of the box or storage area. For that reason, explosive manuals recommend the repeated turning over of boxes of dynamite in storage. Crystals will form on the outside of the sticks causing them to be even more shock, friction, and temperature sensitive. This creates a very dangerous situation. While the risk of an explosion without the use of a blasting cap is minimal for fresh dynamite, old dynamite is dangerous. Modern packaging helps eliminate this by placing the dynamite into sealed plastic bags, and using wax coated cardboard.
Dynamite is moderately sensitive to shock. Shock resistance tests are usually carried out with a drop-hammer: about 100 mg of explosive is placed on an anvil, upon which a weight of between 0.5 and 10 kg is dropped from different heights until detonation is achieved. With a hammer of 2 kg, mercury fulminate detonates with a drop distance of 1 to 2 cm, nitroglycerin with 4 to 5 cm, dynamite with 15 to 30 cm, and ammoniacal explosives with 40 to 50 cm.
For several decades beginning in the 1940s, the largest producer of dynamite in the world was the Union of South Africa. There the De Beers company 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 it was already producing 340,000 cases, 23 kilograms (50 lb) each, annually. A rival factory at Modderfontein was producing another 200,000 cases per year.
There were two large explosions at the Somerset West plant during the 1960s. Some workers died, but the loss of life was limited by the modular design of the factory and its earth works, and the planting of trees that directed the blasts upward. There were several other explosions at the Modderfontein factory. After 1985, pressure from trade unions forced AECI to phase out the production of dynamite. The factory then went on to produce ammonium nitrate emulsion-based explosives that are safer to manufacture and handle.
Dynamite was manufactured by the E. I. du Pont de Nemours Company until the mid-1970s. Other American dynamite makers of that time period included the Hercules Corporation, Atlas, Trojan US Powder, Austin, and several other smaller firms.
Currently only Dyno Nobel manufactures dynamite in the US. The only facility producing it is located in Carthage, Missouri, but the material is purchased from Dyno Nobel by other manufacturers, who put their label on the dynamite and boxes.
Other explosives are often referred to or confused with dynamite:
Though both TNT and dynamite are high explosives, there is little similarity between them. Dynamite is a stabilized form of nitroglycerin while TNT is the chemical compound trinitrotoluene. The energy density (measured in units of joules per kilogram, symbol J/kg) of dynamite is approximately 125% that of TNT: 5.0 MJ/kg for dynamite vs 4.0 MJ/kg of TNT.
In the United States, in 1885, the chemist Russell S. Penniman invented "ammonium dynamite", a form of explosive that used ammonium nitrate as a substitute for the more costly nitroglycerin. Ammonium nitrate has only 85% of the chemical energy of nitroglycerin.
It is rated by either "weight strength" (the amount of ammonium nitrate in the medium) or "cartridge strength" (the potential explosive strength generated by an amount of explosive of a certain density and grain size used in comparison to the explosive strength generated by an equivalent density and grain size of a standard explosive). For example, high-explosive 65% Extra Dynamite has a weight strength of 65% ammonium nitrate and 35% "dope" (the absorbent medium mixed with the stabilizers and additives). Its "cartridge strength" would be its weight in pounds times its strength in relation to an equal amount of ANFO (the civilian baseline standard) or TNT (the military baseline standard). For example, 65% ammonium dynamite with a 20% cartridge strength would mean the stick was equal to an equivalent weight strength of 20% ANFO.
"Military dynamite" is a dynamite substitute, formulated without nitroglycerin. It contains 75% RDX, 15% TNT, 5% SAE 10 motor oil, and 5% cornstarch, but much safer to store and handle for long periods than Nobel's dynamite. Military dynamite achieves greater stability by avoiding the use of nitroglycerin and uses much more stable chemicals.
Various countries around the world have enacted explosives laws and require licenses to manufacture, distribute, store, use, possess explosives or ingredients.
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- Carlos López Jimeno, Emilio López Jimeno, Francisco Javier Ayala-Carcedo, Drilling and Blasting of Rocks, translated by Yvonne Visser de Ramiro from Manual de perforación y voladura de rocas (1987), Geomining Technological Institute of Spain (Instituto Tecnológico Geominero de Espan~a), Taylor & Francis, London and New York, 1995, ISBN 90-5410-199-7
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|Look up dynamite in Wiktionary, the free dictionary.|
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- US patent 78317, Alfred Nobel, "Improved explosive compound", issued 1868-05-26
- Dynamite and TNT at The Periodic Table of Videos (University of Nottingham)