Ammonium nitrate/fuel oil

S. R. Brinkley and W. E. Gordon, "Explosive Properties of the Ammonium Nitrate-Fuel Oil System," in Proceedings of 31st Inst. Congress of Industrial Chemisty, Liege, Belg., 1958. 

Ammonium nitrate-fuel oil mixtures (ANFO) and ammonium nitrate-base water gels marked... 

Special authorisations are available for manufacture at the site of use of ammonium nitrate/fuel oil and certain slurry explosives provided that the equipment used and its position on the site are suitable. 

Ammonium nitrate-fuel oil (ANFO) mixture, in salt mining, 22 806 Ammonium nitrate limestone, 2 726 Ammonium nitrate sulfate, 2 724-725... 

Ammonium nitrate (AN NH4NO3) is a white, crystalline material, the crystal structure of which varies with temperature.melting point is 442 K and its heat of fusion is 71.4 kj kg . Though the mass fraction of oxygen of AN is 0.5996, it is highly hygroscopic and absorbs moisture from the atmosphere to form liquid AN acid. This limits its application in propellants and pyrolants. However, AN is widely used as an oxidizer of explosives such as slurry explosives and ANFO (ammonium nitrate fuel oil) explosives. 

The physicochemical properties of explosives are fundamentally equivalent to those of propellants. Explosives are also made of energetic materials such as nitropolymers and composite materials composed of crystalline particles and polymeric materials. TNT, RDX, and HMX are typical energetic crystalline materials used as explosives. Furthermore, when ammonium nitrate (AN) particles are mixed with an oil, an energetic explosive named ANFO (ammonium nitrate fuel oil) is formed. AN with water is also an explosive, named slurry explosive, used in industrial and civil engineering. A difference between the materials used as explosives and propellants is not readily evident. Propellants can be detonated when they are subjected to excess heat energy or mechanical shock. Explosives can be deflagrated steadily without a detonation wave when they are gently heated without mechanical shock. 

Before anything else can be said about IEs, some rudimentary chemistry is needed. From a cookbook perspective, all explosives (be they military, commercial, or improvised) require the same chemical building blocks, which consist of a fuel and an oxidizer. Some explosives have the fuel and oxidizer as part of the same molecule, such as trinitrotoluene (TNT), and some explosives are comprised of mixtures of separate fuels and oxidizers, such as ammonium nitrate-fuel oil (ANFO). The oxidizer employed by the vast majority of explosives tends to be the NO2 (nitro) group. It is so predominant as an explosive ingredient that the primary focus of detection methods traditionally has been to look for nitro-derived properties. IEs tend to utilize a more diverse range of oxidizers. Table 3.1 gives a list of the numerous oxidizer possibilities. 

In actual field use explosion product fumes can be hazardous, eg Ammonium Nitrate-fuel oil mixtures (ANFO) are not recommended for underground blasting because they produce toxic fumes (Ref 3). Highly toxic NO is often found in explosion fumes. The oxidation of NO to the less dangerous N02 was found to be less rapid under mining conditions than was previously believed (Ref 4)... 

This distinction is more in kind than in degree. Small quantities of primary or initiating explosives usually detonate when exposed to flames or high temperatures whiie secondary explosives usually burn or deflagrate under these conditions. However under slightly altered conditions primary explosives can be made to deflagrate and secondary explosives can be made to detonate. Examples of primary explosives are Lead Azide, Mercury Fulminate, DDNP, etc Examples of secondary explosives are PETN, RDX, HMX, Tetryl, TNT, as single HE compns and Comp B, Comp C, PBX 9404, Dynamite ANFO (Ammonium Nitrate/Fuel Oil) as HE mixtures... 

AN—FO (Ammonium Nitrate—Fuel Oil), called in Italy NA-OC (Nitrato ammonico—Olio combustibili). Belgrano (Ref 31, pp 318—19) gives a standard compn consisting of prilled ... 

Y.N. Tsuchiya, Crystal Habit Modification of Ammonium Nitrate. III. Application to Ammonium Nitrate-Fuel Oil Explosives , KKK 23, 78-83 (1962) (in Engl) CA 58,... 

Figure B.36 Sack of ammonium nitrate fuel oil (ANFO).

Explosives Sensitivity Data. Card-gap and projectile sensitivity, data are presented by Watson (Ref 1) for a wide variety of expl compns tested at the USBurMines laboratories in more or less standard test geometries. The results of both tests are in good agreement in that they provide the same sensitivity ordering fbr different subclasses of expls. Least sensitive were homogeneous liquids that did not exhibit a tendency, to undergo low-velocity detonation, AN-FO (Ammonium Nitrate-Fuel Oil), and most cast military expls. Of intermediate sensitivity were pressed and powdered military expls, cast Pentolite, permissible and nonpetmissible water-based expls, and one commercial two-component expl. The most sensitive were permissible and nonpermissible Dynamites and expls susceptible to low-velocity detonations Refs I) R.W. Watson, 1 Card-Gap and Projectile Impact Sensitivity Measurements, A Compilation , USBurMines Information Circular 1C 8605(1973)... 

MFurther Srudies on Ammonium Nitrate—Fuel Oil Compositions , SthAnnSynp on Mining Research, Nov 19—20(1959), UnivMissouriSchool-Mifling 4) CondChemDiet(1961), 517-R St 8th Edit (1971), 403-R 3) US Spec W-F-815C... 

Civil explosives are further sub-divided into permitted or permissible explosives and non-permitted explosives. Two types of civil explosives namely ammonium nitrate-fuel oil (ANFO) and emulsion explosives dominate the rock blasting scene in the USA. 

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