Ammonium nitrate mining explosives

The density of nitropolystyrene is very low, due to its fluffiness . Medard suggested its use in the manufacture of ammonium nitrate mining explosives of low density, hence of a relatively low power. The following figures give some idea of such mixtures ... 

The hygroscopicity of ammonium nitrate is its great drawback. The probleir. occurred particularly with the use of ammonium nitrate mining explosives their storage and use in damp places. Tlic usual method of reducing hygroscopicity consists in incorporating small proportions of calcium, zinc and iron salts of fatty acids, usually stearic acid. 

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). 

Inorganic oxidizers are widely used as blasting agents in mining and construction explosives and also in improvised explosive devices utilized by terrorists. Ammonium-nitrate-based explosives (e.g., ammonium nitrate and fuel oil — ANFO) have almost completely replaced the majority of dynamites. In addition, slurry and emulsion explosives, which contain mosdy ammonium nitrate and a small amount of other oxidizers, have become widely used. 

Ammonium nitrate based explosives are generally used for quarrying, tunnelling and mining. They are mixtures of ammonium nitrate, carbon carriers such as wood meal, oils or coal, and sensitizers such as nitro-glycol, TNT and dinitrotoluene. These compositions may also contain aluminium powder to improve their performance. 

Many expls described under BLASTING EXPLOSIVES Vol 1, pp B202ff of this Encycl, can be used in coal mining LSee also AMMONIUM NITRATE BLASTING EXPLOSIVES in Vol 1, pp A34lff AMMONIUM NITRATE DYNAMITE in Vol 1, pp A355 ... 

All the above considerations lead to imposing a limited storage time on mining explosives. In Poland ammonium nitrate permitted explosives should be used within 114-3 months from the production date. Non-permillcd ammonites... 

The main factors leading to spontaneous explosions of blasting explosives in sulfide ore mines are identified as presence of ammonium nitrate, presence of pyrites and their weathering products, as well as the pH and temperature. At pH below 2, the critical temperature for spontaneous explosion may be lower than 40°... 

VanDolah et al, "Explosion Hazards of Ammonium Nitrate Under Fire Exposure , USBur-Mines Report of Investigation R1 6773(1966)... 

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)... 

A mixture of ammonium nitrate/TNT/aluminum powder/charcoal (65/15/17/3) called Ammonal had been used in World War I for mining, demolition and in bombs and grenades. However, in World War II, shortage of aluminum powder restricted its use for such HE formulations. The effect of addition of aluminum powder to high explosive fillings of bombs and shells had been found to be of advantage which is evident from the data given in Table 3.3. 

In mining, a No. 8 detonator is used for ammonium nitrate explosives, No. 6 and No. 3 for nitroglycerine explosives. 

Ohlsson and Norrbin [46] suggested another type of ammonium nitrate explosive for mining purposes (see p. 395). 

The preparation of infusible (loose powder) ammonium nitrate mixtures is usually carried out in the same way as the manufacture of composite mining explosives. Since the military explosives are not very sensitive to mechanical stimulants, and it is important to obtain a high density, mixing is usually performed by edge runner mills. 

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