Dynammons

(in Russian, dinamony), secondary explosives that consist of a mixture of ammonium nitrate (the oxidizer) with powdered or liquid fuels (wood shavings, peat, carbon black, powdered aluminum or ferrosilicon, paraffin, mazut, or other materials). The explosive characteristics of dynammons, such as the rate and the critical diameter of the detonation, vary within wide limits depending on the degree of particle size reduction and on the thoroughness of mixing of the components.

Dynammons were invented as early as the 19th century, but their practical application did not begin until the 1930’s. Because of a shortage of explosives during World War II (1939-45), dynammons were used almost exclusively in blasting operations in the mining industry and other industries. They were also used for arming ammunition. Dynammons were particularly widely used during the 1950’s in connection with the use of granulated or flaked ammonium nitrate (usually used as fertilizer) for their manufacture. Dynammons prepared even by relatively rapid mixing (sometimes even at the site of their application as explosives) of these forms of ammonium nitrate with liquid petroleum products (solar oils, ligroin, and other materials) acquire adequate explosive power and detonate in charges with the diameters of 10-20 cm. In this case, the detonation is initiated by a charge of a powerful explosive (pentolite, dynamite, or a similar material). Particularly good results are obtained by using microporous ammonium nitrate, which readily absorbs liquid fuels. In this case, the explosion may be initiated by an ordinary detonating cap. The maximum heat of explosion (~4,200 kilojoules per kilogram, or 1,000 kilocalories per kilogram) may be achieved with a fuel content of only 6 percent. Abroad, these dynammons are called AN-FO (ammonium nitratefuel oil) mixtures; in the USSR they are called igdanity. They are several times less expensive than the ordinary industrial explosives and are simple to produce and safe to handle. Hundreds of thousands of tons of AN-FO mixtures are used annually in the USA and Canada. Industrial dynammons used in the USSR are based on granulated (so-called granulity) or crystalline ammonium nitrate and contain wood shavings or aluminum power in addition to petroleum products.

The main disadvantage of dynammons is low physical stability, which is linked to the hygroscopicity of ammonium nitrate and its high solubility in water.