ANFO

Table 19. Cratering Characteristics of ANFO, Slurry Explosives, and TNT ...

Most limestone quarries use either 100% ammonium nitrate [6484-52-2] (fertilizer grade) and fuel oil (ANFO), or a combination of ANFO and ammonium or gelatin dynamite, for blasting (see Explosives and propellants, explosives). After blasting, oversized boulders usually are reduced to manageable sizes by drop ball cranes. 

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

In 1955 it was discovered that mixtures of ammonium nitrate and fine coal dust have satisfactory blasting capabilities in large (9 inch) holes used in open-pit coal mines to remove the rock and soil covering the coal. Polyethylene bags containing this material deform to fit the hole and provide moderate water resistance. ANFO is used in open-pit iron and copper mines and for construction such as road building. The mixture is air blown into 2-inch holes or less m maiiv underground mines. 

In recent years the most commonly used expl in mining has been ANFO (94/6 AN/Fuel Oil). Ref 16 quotes 55 < PCJ 61 kbar for very large charges of ANFO... 

The simplest explosive to design is ANFO, or ammonium nitrate mixed with fuel oil. The choices to be made here are the grades of ammonium nitrate and oil and the proportion in which they are mixed. 

In many ways slurries may be considered as intermediate between ANFO and nitroglycerine explosives. They are more expensive than ANFO but can be used in wet conditions they are often cheaper and safer than nitroglycerine explosives but are more critical of conditions of use if misfires are to be avoided. 

Further properties which a detonating fuse should have are the ability to initiate blasting explosives (tested with suitable relatively insensitive mixtures usually of TNT and ammonium nitrate) resistance to low temperatures without cracking on flexing and to hot storage without desensitisation and toughness to prevent damage from stones, etc. The fuse must always be waterproof and must often withstand diesel oil, which can separate from ANFO. 

Zimmermann, R. Die Abhangigkeit des Arbeitsvermogens der ANFO-Sprengstoffe von der Zundweise, FldT-Seminar Fels- und Gewinnungs-sprengtechniktage", Essen 1983. 

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