Chlorate explosives

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Chlorate explosives (also chloratites ) are non-homogeneous explosives based on chlorates . Mixtures of chlorates of the alkali metals sodium and potassium with carbon-rich organic compounds such as. B. wood flour , petroleum, oils, fats or nitro derivatives of benzene , toluene or naphthalene . Chlorate explosives have not been manufactured in Germany since the end of the Second World War .

history

In 1786, the French chemist Claude-Louis Berthollet obtained a previously unknown salt, potassium chlorate , by introducing chlorine into a hot potassium hydroxide solution in addition to potassium chloride , which easily gave off oxygen when heated . Berthollet called the new salt "over-oxidized hydrochloric potash" . He soon had the idea of using chlorate as a substitute for potassium nitrate to make a new gunpowder , since a product made with potassium chlorate was much more explosive than the conventional one. First attempts together with de Lavoisier in a state powder factory in Corbeil led to several fatal accidents because of the high impact sensitivity of the chlorate. To produce a less dangerous chlorate explosive, the sulfur was initially omitted and later other components such as starch , rosin or sugar were introduced as a substitute for the charcoal powder. Due to negative effects on firearms, such as corrosion , the use as gunpowder was soon abandoned. From 1870 the chemists PA Blake and Hermann Sprengel adopted the principle of initial ignition using fumed mercury for chlorate explosives, which is why some chlorates were also referred to as " Sprengel explosives ". In addition to chlorate, Sprengel first used various - mostly liquid - organic nitro compounds such as nitrobenzene , nitronaphthalene and picric acid as components .

Properties and types

Chlorate explosives are non-homogeneous explosives, i. This means that they consist of at least two components: a strong oxidizing agent (chlorate) and an oxidizable substance . With the first types as a gunpowder substitute, the potassium chlorate was mixed with sulfur and charcoal, creating a mixture that was explosive but also extremely sensitive to impact and friction. All later chlorate explosives contained other oxidizable substances instead of coal and sulfur; these were initially simple organic mixtures such as starch, flour or sugar. Later, liquid organic solvents - such as liquid hydrocarbons - were added; the resulting mixtures were called chloratites . PA Blake, Hermann Sprengel and EAG Street used more viscous oils and additional organic nitro compounds , which increased the strength of the explosion and at the same time reduced the sensitivity to friction. When using viscous solvents, the chlorate explosives are called cheddite . The United States Dept. of the Army reported in 1992 on the production of gelatine cheddite as a plastic explosive for military purposes in Switzerland .

Chloratites

Chloratit 1 and Chloratit 2 consist of 70–80% or 70–85% potassium or sodium chlorate , 12–20 or 10–20% organic nitro compounds, 1–5% vegetable meal and 3–5% hydrocarbons, oils or fats . For Chloratit 1, 2-6% nitroglycerin was added. Chloratit 3 contains 88–91% potassium or sodium chlorate, 9–12% organic hydrocarbons and an addition of wood flour. The detonation speed in the explosion is only 3.35 km / s −1 for Chloratite 3 , but its explosive power is ~ 1 TNT equivalent (explosive power in relation to that of TNT). These friction-sensitive mixtures have been largely replaced by handling-safe explosives.

Cheddite

Explosive mixtures of chlorates with binders / solvents such as oils, resins or nitrocellulose with the addition of nitro compounds are called cheddites . These are usually much tougher than the chloratites and most closely resemble chloratite 2.

Explosive mixes

Mixtures with easily oxidizable substances such as sulfur , phosphorus , iodine and carbon , which can explode through friction, impact or impact, are very explosive . The most explosive mixtures are with red phosphorus and are considered dynamite-like (" Armstrong mixture ") when mixed finely . In technology, quantities in the single-digit milligram range are therefore only mixed wet and used with binding agent for popping corks and ignition leaflets. Mixing the dry components with a bird's feather used in lecture experiments is too dangerous and unnecessary, since, according to A. Stettbacher, the mixture can be done safely in 96 percent ethanol and only takes place after the alcohol has evaporated under pressure. This also occurs when the chlorate is mixed with organic substances, e.g. B. wood flour or kerosene after friction, impact or initial ignition . This has often resulted in accidents.

Use restriction

In the EU , chlorate explosives with a chlorate content of over 85% may only be used in salt mining .

literature

Individual evidence

  1. ↑ a b Wissenschaft-Online-Lexika: Entry on chlorate explosives in the Lexikon der Chemie, accessed on August 6, 2009
  2. ↑ Annales di Chimie. Vol. IX, p. 22
  3. ↑ Journal de Paris of October 31, 1788
  4. ↑ F. Wolff: Instructions to prepare the gunpowder. Berlin, 1816
  5. ↑ J. Chem. Soc. 796 (1873).
  6. ↑ United States Dept. of the Army: Military explosives. Headquarters Dept. of the Army, 1992
  7. ↑ Moritz Ferdinand Gaetzschmann: Complete Guide to Mining Art , Volume 3. JG Engelhardt, 1846, p. 221
  8. ^ Hermann Römpp: Chemie Lexikon, Volume 1. 3rd edition, Franckh-Verlag, 1952, p. 331
  9. ↑ Entry on chlorate explosives. In: Römpp Online . Georg Thieme Verlag, accessed on July 25, 2015.
  10. ↑ A. Stettbacher: Spreng- und Schießstoffe , Zurich 1948