Properties of Ammonium Nitrate

Ammonium nitrate-based explosives account for about 97% of total U.S. industrial explosive consumption. Coal mining in the United States formed about 65—68% of the demand for explosives in 1991. The remaining uses were quarrying and nonmetal mining, 15% metal mining, 10% constmction, 7% miscellaneous uses, 3—4%. The properties of ammonium nitrate are given in Table 18 (173,239—242). 

Fig. 156. Explosive properties of ammonium nitrate-mineral oil mixtures as a function of mineral oil content [71],...

Medard and Le Roux [1] examined the influence of various methods of mixing on the properties of ammonium nitrate explosives ( Explosifs du type N ). They found that mixing in heavy (5 ton) edge-runners gives explosives of higher sensitiveness and rate of detonation than the same explosives mixed in kneaders of the Werner-Pfleiderer type. 

Numerous shipments were made without trouble prior to 16 and 17 April 1947, when a terrible explosion occurred. The SS Grandchamp and the SS Highflyer, both moored in the harbour of Texas City and loaded with FGAN, blew up. As a consequence of these disasters, a series of investigations was started in the USA in an attempt to determine the possible causes of the explosions. At the same time a more thorough study of the explosive properties of ammonium nitrate and its mixtures with organic and inorganic materials was also conducted. The explosion at Texas City had barely taken place when a similar one aboard the SS Ocean Liberty shook the harbour of Brest in France on 28 July 1947. 

There are many other ingredients that are added to explosive compositions which in themselves are not explosive but can enhance the power of explosives, reduce the sensitivity, and aid processing. Aluminium powder is frequently added to explosive and propellant compositions to improve their efficiency. Ammonium nitrate (NH4N03) is used extensively in commercial explosives and propellants. It is the most important raw material in the manufacture of commercial explosives and it also provides oxygen in rocket propellant compositions. Some of the properties of ammonium nitrate are presented in Table 2.22. 

Attention was paid to the explosive properties of ammonium nitrate as early as 1883 by Berthelot [10] who first formulated the equation of decomposition, and gave the numerical data for the heat of explosion, heat of formation, the volume of gases evolved and the temperature of explosion. 

This accident caused a re-investigation of the explosive properties of ammonium nitrate mixed with fuel oil. A considerable amount of work was done by several authors particularly in the Explosives Research Laboratories, U.S. Bureau of Mines. 

Some of the physical and chemical properties of ammonium nitrate are given in Table 10.2103. 

Covering particles of ammonium nitrate with non-hygroscopic layers of polymers, such as polyvinyl compounds. This however should be Uiniied to substances which could not produce harmful influence on the explosive properties of ammonium nitrate and (for underground work) would not give harmful products after detonation, such as chlorine compounds from polyvinyl chloride. 

A5 is wc]J known ammonium nitrate is the most popular oxygen carrier in explosive mixtures which is also widely used as a fertilizer. Subsequently there is voluminous literature on the properties of ammonium nitrate. Among the greatest problems is its caking. It continues to raise interest and an excellent review has appeared recently [1). 

Ammonium nitrate (NH4NO3) is used extensively in commercial explosives and propellants. It is the most important raw material in the manufacture of commercial explosives and it also provides oxygen in rocket propellant compositions. Some of the properties of ammonium nitrate are presented in Table 2.27. 

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