How do I detonate ANFO




   

A explosive is a chemical substance or a mixture of chemical substances that react very quickly under certain conditions and release a relatively large amount of energy in the form of a pressure wave (often with heat generation) (detonation). The speed at which the reaction spreads in the explosive is above the speed of sound within the explosive (based on the substance itself). An object that can detonate becomes explosive called. This applies in particular to primers.

The explosives belong together with the Initial explosives, Propellants and explosives (Black powder and gunpowder or propellant powder), Ignition means and pyrotechnic products to the explosive substances (Explosives).

introduction

Modern explosives are mostly based on energetic compounds that contain the chemical elements carbon (C), hydrogen (H), nitrogen (N) and oxygen (O). During the explosion, the oxygen originally weakly bound to nitrogen usually combines with the carbon to form CO and CO2 as well as with the hydrogen to water vapor, while the nitrogen the very stable nitrogen molecule N2 forms. During this conversion, a large amount of heat is normally released within a few microseconds or milliseconds, and the reaction products that arise during the conversion of the explosive are also gaseous due to the heat of several thousand degrees Celsius. The sudden emergence of very hot gases, which take up a lot of space, from a solid or liquid, then results in the pressure wave typical of explosives. The explosive effect is drastically increased by the high temperature of the gases, because the more heat the explosive releases during detonation, the higher the gas pressure. A temperature that is as high as possible thus contributes to the greater explosive effect. However, the pressure also depends on other factors. Oxygen carriers are also added to some explosives, on the one hand to improve the oxygen balance, on the other hand to stretch high-performance explosives and in this way meet a high demand. In Germany, for example, towards the end of the Second World War, the proportions of high-performance explosives in explosives used by the military were continually reduced and replaced by all available saltpeter and low-oxygen substitute explosives. Shortly before the end of the war, explosives containing alkali chloride were even used to fill ammunition.

Both civil and military explosives sometimes still contain metals such as aluminum or zinc. While finely powdered aluminum increases the gas impact effect through higher temperatures, aluminum or zinc grit in anti-aircraft ammunition is used to increase the fire effect in the target.

Detonators are used to initiate explosives. There are electrical, non-electrical, and electronic ignition systems. The world's leading manufacturer of ignition systems for the civil sector is the Orica Group based in Melbourne, Australia. In addition, detonators are occasionally used, which are ignited by means of a safety fuse. If the main charge consists of a very insensitive explosive, an additional boosting charge (booster, impact amplifier) ​​is required between the detonator and the main charge.

history

The first synthetic explosives were glycerin trinitrate in 1847 and cellulose nitrate in 1846, better known under the incorrect names nitroglycerin and nitrocellulose or gun cotton. Since glycerol trinitrate is very sensitive to vibrations and insufficiently neutralized cellulose nitrate tends to self-ignite, for which the cause was initially not recognized, handling was initially very dangerous. In 1862 Alfred Nobel invented the initial spark and in 1867 he succeeded in producing dynamite that is insensitive to vibrations by absorbing glycerol trinitrate in diatomaceous earth. In 1875, Nobel found blasting gelatine, the strongest commercial explosive at the time, by gelatinizing the liquid glycerol trinitrate with 6 to 8% solid cellulose nitrate. Since the blasting gelatine was still quite sensitive to impact and was expensive, so-called "gelatinous explosives" were developed by adding wood flour and nitrates. They are safe to handle and sensitive to detonators. In the meantime, especially in the field of extraction blasting, they are being replaced by ammonium nitrate explosives of the ANC / ANFO type, which have been further developed into blasting sludge and emulsion explosives.

Picric acid and m-trinitro-cresol, whose raw materials were obtained from coal tar, were among the oldest explosive military explosives. However, these had the major disadvantage that they formed shock-sensitive heavy metal picrates on the inner wall of the grenades, which led to gunshots. For this reason, the grenades were painted inside before filling. When petroleum distillation was able to provide enough toluene, TNT replaced its predecessors as a frequently used, very safe to handle, explosive military explosive.

Modern high explosives are often based on hexogen, nitropenta or ethylenedinitramine. Octogen is one of the most explosive explosives, but it is complex and very expensive to manufacture. It is used almost exclusively for special charges, for example shaped charges, when very high explosiveness is required.

Parameters for the characterization of explosives

Oxygen balance

The Oxygen balance indicates whether too much or too little oxygen is available to completely oxidize the explosive. The more balanced the oxygen balance (the closer to zero), the higher the temperature and the stronger the explosive effect. In the case of military uses of explosives, the oxygen balance is irrelevant; in the case of explosives for commercial purposes, it should always be positive in order to avoid the formation of flammable or toxic reaction products. The oxygen balance of explosives, which in their pure form have a negative oxygen balance, can be influenced by adding oxygen carriers (e.g. ammonium nitrate).

Specific vapor volume (normal gas volume)

The Specific vapor volume is the volume of gas under normal conditions that is created when 1 kg of explosive is completely converted.

From the number of moles N of the gaseous detonation products (vapor) per gram of explosive, the specific vapor volume results in:

Specific energy

The Specific energy indicates the pressure (in megapascals) that one kilogram of an explosive in a closed volume of one liter would generate in the event of an explosion. This parameter depends on the specific vapor volume and the explosion temperature.

Loading density

Ratio of the weight of the explosive to the volume of the explosion space. The speed of detonation depends on the charge density.

Sensitivity to impact

The sensitivity of explosives against mechanical impact (impact, impact) can be reduced by adding phlegmatizing substances such as paraffin. The phlegmatization of explosive mixtures is called inerting. The sensitivity can also be increased by adding so-called sensitizers.

Some explosives data

Characteristics of some selected explosives, as they are usually determined empirically from standardized experiments such as the lead block bulge:

Gunpowder Propanetriol
trinitrate (nitroglycerin)
Ethanediol
dinitrate (glycol dinitrate)
Shooting
cotton
Pentaerythritol
tetranitrate
Trinitrotoluene (TNT)
Melting
temperature
° C
-- 13,5 -22 decomposes at 180 141 81
density

g / cm³
1,1 1,6 1,49 1,67 1,77 1,65
Oxygen-
balance sheet
%
-18 +3,5 ±0 -29,6 -10,1 -74,0
Explosive
warmth
kJ / kg
2784 6238 6615 4396 5862 3977
Swath
volume
l / kg
337 740 737 869 780 740
Specific energy
(l * MPa) / kg
285 1337 1389 1003 1327 821
Detonation
speed
m / s
400 7600 7300 6800 8400 6900
Explosive
temperature
K
2380 4600 4700 3150 4200 2820
according to Ammedick[1]

use

Civil explosives are mostly used for the extraction of rock in open-cast mines (quarries: basalt, granite, diabase, lime etc.), for stone extraction and in mining (hard coal, potash & salt, gypsum, ore mining, etc.). They are also used in traffic route construction, tunnel construction, demolition, seismic explosions and pyrotechnics (fireworks). The production of commercial explosives in Germany in 2004 was around 65,000 tons. ANC explosives accounted for approx. 36,000 tons, gelatinous explosives based on NG approx. 10,000 tons, and pumped and cartridged emulsion explosives for approx. 16,000 tons. The remaining amount is divided into weather explosives for coal mining and black powder for stone extraction. Leading manufacturers of industrial explosives in Germany are Orica, Troisdorf, Westspreng, Finnentrop, ACF, Gnaschwitz and WASAG AG, Sythen.

Military explosives are used as fillers for grenades, bombs, mines, warheads for missiles and torpedoes, and as components of propellants. They are also used in various pyrotechnic charges. A special point is the use in nuclear weapons to initiate a chain reaction.

For terrorist purposes, both military and civil explosives as well as substances and mixtures that can be produced from easily accessible chemicals (so-called self-laboratories) are used. Examples are the mixture of powdered sugar and a weed killer containing chlorate or mixtures based on ammonium nitrate. Mixing such explosives is very dangerous as it can detonate unpredictably.

Legal

Handling, including manufacturing, processing, processing, using, moving, transporting and leaving the premises, recovering and destroying, traffic (trade) and import are regulated in explosives law due to the possible risk.

See also: Ammunition depot

Types of explosives

Technically used explosives are usually mixtures of energetic chemical compounds, binders, plasticators and other additives. They are divided into the following groups:

According to DIN 20163, explosives are divided into:

Examples:

  • Gunpowder (the oldest known explosive) is called Explosive powder, depending on the use, assigned to explosives or explosives or pyrotechnic chemicals.
  • Chlorate explosives consist of alkali and alkaline earth chlorates in combination with organic substances such as waxes, oils, wood flour or substitute explosives (dinitroaromatics). After their development at the end of the 19th century, they were widely used, but fell out of use because of their high sensitivity to friction.
  • To Dynamites includes both the kieselgurdynamite developed by Alfred Nobel and the “gelatine dynamite” developed from explosive gelatine.
  • Gelatinous explosives consist of explosive oils such as glycerol trinitrate, ethylene glycol dinitrate or diethylene glycol dinitrate or mixtures thereof which are gelatinized with 6 to 8% cellulose nitrate or collodion wool to reduce impact sensitivity.
  • Powder explosives (Ammonium nitrate/Carbones) are particularly safe as they require a booster to ignite. They consist of ammonium nitrate and carbon carriers such as coal powder, naphthalene or wood flour. The ammonals also contain aluminum powder.
  • ANFO (Ammonium nitrate/Fuel oil) consist in the simplest case of 94.5% ammonium nitrate and 5.5% heating oil. They are a subset of the ANC explosives.
  • HAPAN
  • To Blasting sludgeWhat counts today is primarily mixtures of concentrated aqueous ammonium nitrate solutions with a low proportion of explosive substances, which are characterized by particularly high processing and transport safety. They are only manufactured with mixed-load vehicles shortly before use, i.e. when they are poured into a borehole. During the transport to the blasting site, the individual components are housed separately from each other in tanks. This means that the transport does not fall into class 1 of the ADR.
  • Emulsion explosives consist of concentrated aqueous ammonium nitrate solutions with mineral oil emulsified in them.
  • Specific Weather explosivesare used underground in coal mining. Due to the addition of alkali chlorides, their explosion temperature is not sufficient to trigger dust or methane gas explosions (heavy weather).
  • Oxyliquite consist of absorbent materials such as wood or cork flour, which are immersed in liquid air or liquid oxygen shortly before use. Since these evaporate again, they have to be ignited shortly afterwards. For this reason, Oxyliquites are not suitable for large-scale blasting. Their advantage is that charges that have not been ignited are absolutely harmless after the oxidizer has evaporated.
  • The Picric acid is one of the longest known explosive explosives, but was later largely used by the TNT replaced. Modern explosives often contain the more explosive hexogen, ethylenedinitramine or nitropenta.
  • The malleable explosives used by the military (Plastic explosives) such as C4 or Semtex contain Nitropenta, Hexogen and plasticizers. They are primarily used for pioneering purposes, but are also popular with terrorists because they are easy to bring into inconspicuous form.
  • High explosives
  • Polymer-bound explosives (PBX): Panclastit consists of 70% dinitrogen tetroxide and 30% nitrobenzene, which are only mixed shortly before use. A similar mixture of 86.5% tetranitromethane and 13.5% toluene achieves a detonation speed of 9300 m / sec
  • dibasic liquid explosives

   

Basic substances for explosives of practical importance

Basic substances for explosives of less importance

Basic substances for substitute explosives

Oxygen carriers for mixed explosives

Basic substances in the experimental stage

literature

  • Manuel Baetz: Black powder for survival. Improvisation of black powder and similar mixtures. Survival Press, Radolfzell 2005, ISBN 3937933077.
  • Rudolf Biedermann: The explosives - their chemistry and technology. Reprint 2000 edition. Survival Press, Radolfzell 1918, ISBN 3898118398.
  • Richard Escales: The explosives. In: Initial explosives. Reprint 2002 edition. 7th volume, Survival Press, Radolfzell 1917, ISBN 3831139393.
  • Jochen Gartz: From Greek fire to dynamite. A cultural history of explosives. IT. Mittler & Sohn, Hamburg 2007, ISBN 978-3-8132-0867-2
  • Oscar Guttmann: Handbook of Blasting Work. Survival Press, Radolfzell 1899, Reprint 2001, ISBN 3831130957
  • Fritz Hahn: Weapons and secret weapons of the German army 1933-1945. Bernard & Graefe, 1998, ISBN 3763759158
  • R. Knoll: The fatal mercury and similar explosives. Survival Press, Radolfzell 1917, Reprint 2001, ISBN 3831128766
  • A. Langhans: Explosives in the chemical laboratory - explosions you don't expect. Survival Press, Radolfzell 1930, Reprint 2006, ISBN 978-3-937933-18-4
  • S.J. from Romocki: History of explosives. Part 1. Explosives chemistry, blasting technology and torpedo beings. Survival Press, Radolfzell 1895, Reprint 2003, ISBN 3833007028
  • S.J. from Romocki: History of explosives. Volume 2. The low-smoke powder in its development up to the present. Survival Press, Radolfzell 1896, Reprint 2004, ISBN 393793300X

Legislation and standards:

  • Germany: Explosives Act - Bavarian State Office for Occupational Safety, Health and Safety Technology
  • Austria: Guns and Explosives Act - in RIS.BKA as a search term
  • Switzerland: Federal Act on Explosive Substances (Explosives Act) - admin.ch
  • Switzerland: Ordinance on explosive substances (Explosives Ordinance, SprstV) - admin.ch

Individual evidence

  1. Erich Ammedick: Military chemistry. An introduction. In: Building blocks of chemistry. 4th edition. VEB German publishing house for basic industry, Leipzig 1980, ISBN 978-3342000372.
  2. The explosive made of sand, Jeanne Rubner - scan of the article, Physics Department, TU Munich
  3. Koch, Ernst-Christian; Clément, Dominik: Special Materials in Pyrotechnics: VI. Silicon - An Old Fuel with New Perspectives. In: Propellants Explosives Pyrotechnics 32 (2007), No. 3, pp. 205–212 [1]

Category: Explosives