Ammonium nitrate detonation rate

Medard [20], for instance, recommends a mixture of 62% ammonium nitrate and 38 % trimethylolpropane trinitrate. Such a mixture has on oxygen balance corresponding to complete combustion. A charge with a diameter of 30 mm and a density of 1.50 detonates with a rate of 6150 m/sec, and a charge with a density of 1.10 detonates with a rate of 4230 m/sec. Its lead block expansion is 127.5 (taking picric acid as 100). 

A mixture of 40% ammonium nitrate and 60% trimethylolpropane trinitrate may be melted at 60°C and used as a poured filling for shells. The substance solidifies into a mass with a density of 1.36, giving a rate of detonation of 5200 m/sec. 

The explosive properties of mixtures with ammonium nitrate depend on the quantitative relationship between the oxidizing agent and the explosive or combustible substance. According to Parisot and Laffitte s [9, 47] investigations the explosive properties of mixtures of aromatic nitro compounds with ammonium nitrate vary with the change in composition of the system in an almost rectilinear manner. The graph in Fig. 69 shows how the rate of detonation depends on the composition of mixtures of tetryl or picric acid with ammonium nitrate. T. Urbanski et al. [48] also obtained a rectilinear relationship for nitrostarch mixtures with ammonium or sodium nitrate (Fig. 71, p. 265). 

Fig. 69. The relation between the rate of detonation and the composition of tetryl or picric acid mixtures with ammonium nitrate (Parisot and Laffitte [9]).

The explosive properties of nitrostarch mixtures (containing 12.7% of nitrogen) with ammonium or sodium nitrates have been studied by T. Urbanski et al. [48]. Values for rate of detonation of mixtures with a density of 1.0 are given in Fig. 71. They conform to Laffitte s rule that the variation in rate of detonation with the composition of mixtures with ammonium nitrate is almost rectilinear. 

Fig. 148. Change in the rate of detonation of explosives on storage [71] /—ammonia gelatin, iron tube 1 in. (25 mm) dia., type B with 35% NG //—ammonium nitrate explosive, iron tube 1 in. (25 mm) dia., type II with 6% NG and 76% NH4NO3 ///—ammonium gelatine, cardboard tube 1 in. (40 mm) dia., type B with 35% NG.

Type I—dynamites and rock explosives. The chief ingredients of the latter are ammonium nitrate, nitroglycerine and TNT. Their rate of detonation at a density of 1.1 is about 3800m/sec, their transmission distance 6 cm. 

A modified type of AN-FO explosive has been suggested in the U.S.A., made by mixing ammonium nitrate with nitromethane (ca. 5%)which is itself explosive. They have a higher rate of detonation than AN-FO (e.g. 3900 m/sec). However, they have not been widely used because of their higher price. 

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. 

Class IV. Nongelatinous (powdery) Nitro-gIycerin-Ammonium Nitrate Explosives, known as Ammonium Nitrate Dynamites or Ammonia Dynamites. They contain sub stantial amounts of AN which usually replaces part of NG and of Na nitrate. The replacement of part of Na nitrate by AN increases the volume of gas produced on detonation. They have approximately the same explosive-strength values as do the Gelatin Dynamites, but have lower rate of detonation and brisance values (Ref 62, p640)... 

The rate of detonation of low-density ammonium nitrate was also determined by Fukuyama [36] (Table 113) at different temperatures in steel pipes of 35/40.4 mm dia. The initiation was by a No. 6 detonator. 

Fukuyama also studied the sensitiveness and the rate of detonation of ammonium nitrate containing water. 

He found that ammonium nitrate containing 5-8% of water at a loading density 0.5 can be brought to detonation by a very strong initiator such as a No. 6 detonator with 15 g of TNT. With a 60 g TNT detonator, ammonium nitrate of even 10% water content can detonate in a 35/40.4 mm steel tube at a rate of 1900 m/sec. 

The rate of detonation of ammonium nitrate depends to a large extent on the degree of fineness, the initiator, the density, and the confinement of the charge. It varies within wide limits, from 1100 to 2700 m/sec. 

This was confirmed by Van Dolah [39]. The latter also determined the rate of detonation of paper cartridges of prilled ammonium nitrate with 4% fuel oil at a density of 0.95 ... 

A double salt of ammonium nitrate and sulphate, defined by the formula 2NH4N03-(NH4)2S04, is capable of detonating with a rate of 1000-1400 m/sec... 

Urea nitrate is insensitive to friction and to impact. The density of the substance subjected to a pressure of 1500 kg/cm3 is 1.59 g/cm3. In the lead block test it caused an expansion of 260 (Kast) or 270 cm3 (T. Urbanski, Kapuscinski, Wojcie-chowski [59]). It detonates somewhat better than ammonium nitrate and guanidine nitrate, but a No. 8 detonator did not provoke complete detonation. Medard [59a] reported that urea nitrate gives a relative figure of the lead block expansion 79.6 (picric acid = 100) and the rate of detonation of 30 mm dia. charges is ... 

Application. A mixture of the dinitronaphthalene isomers is used in explosive compositions with picric acid and ammonium nitrate for military and mining explosives (Vol. III). The mixture is often referred to as Dinal . It is also designated by the symbols DN or DNN. It is an explosive very difficult to detonate. The highest rate of detonation of Dinal, when using a very powerful detonator, is about 5100 m/sec (Calvet [32]). 

The ammonium nitrate permissible explosives contain relatively litde nitroglycerin and relatively large proportions of ammonium nitrate. The latter is an explosive but one less sensitive to impact, sparks, and flames than nitroglycerin. This type of permissible explosive is now used extensively, as it has a rather wide range of strength, rate of detonation, density, size of cartridge, etc., and can be utilized not only in dry but also to some extent in fairly wet holes if charged carefully and fired promptly. 

Grubb [62J drew attention to the importance of the intimacy of mixing ammonium nitrate with fuel oil by using fine and porous particles of ammonium nitrate and Clark et al. [63] described the use of micro-prilled ammonium nitrate of less than 20 mesh size. They found the AN -FO made of such ammonium nitrate can readily detonate but the rate of detonation is limited by characteristic low bulk density — the consequence of micro-prills. 

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