The most notable properties of emulsions are water resistance and higher bulk density. They differ from ANFO in the physical form the reactants take. Other explosives based on the ANFO chemistry exist the most commonly used are emulsions. In the mining industry, the term ANFO specifically describes a mixture of solid ammonium nitrate prills and diesel fuel. Industrial use Charging a hole with ANFO for rock blasting It is described as a non-ideal high explosive, as its explosive velocity is far from the thermodynamic ideal due to its porosity and the phase separation of its two components. ANFO has a moderate velocity compared to other industrial explosives, measuring 3,200 m/s in 130 mm (5 in) diameter, unconfined, at ambient temperature. ĪNFO is technically a high explosive in that it decomposes through detonation rather than deflagration at a velocity higher than the speed of sound in the material, but the low sensitivity means that it is not generally regulated as such. One or two sticks of dynamite were historically used current practice is to use Tovex or cast boosters of pentolite (TNT/ PETN or similar compositions). A larger quantity of secondary explosive, known as a primer or a booster, must be used. 8) blasting cap with the small amount of primary explosives within.
Without a sensitizer, it cannot be detonated by a typical (such as No. Explosive properties ĪNFO is highly insensitive, making it a tertiary explosive (or a "blasting agent"). Finely powdered aluminium in the mixture will sensitise it to detonate more readily. The fuel component of ANFO is typically diesel, but kerosene, coal dust, racing fuel, or even molasses have been used instead. In practical use, such conditions are impossible to attain, and blasts produce moderate amounts of toxic gases such as carbon monoxide and nitrogen oxides ( NO x). When detonation conditions are optimal, the aforementioned gases are the only products. In practice, a slight excess of fuel oil is added, as underdosing results in reduced performance while overdosing merely results in more post-blast fumes. In an ideal stoichiometrically balanced reaction, ANFO is composed of about 94.5% AN and 5.5% FO by weight. The chemistry of ANFO detonation is the reaction of ammonium nitrate with a long-chain alkane (C nH 2n+2) to form nitrogen, carbon dioxide, and water. ANFO is also widely used in avalanche hazard mitigation. It has found wide use in coal mining, quarrying, metal ore mining, and civil construction in applications where its low cost and ease of use may outweigh the benefits of other explosives, such as water resistance, oxygen balance, higher detonation velocity, or performance in small-diameter columns. ĪNFO accounts for an estimated 90% of the 2.7 million tonnes (6 billion pounds) of explosives used annually in North America. It consists of 94% porous prilled ammonium nitrate (NH 4NO 3) (AN), which acts as the oxidizing agent and absorbent for the fuel, and 6% number 2 fuel oil (FO). 25 kg (55 lb) sacks containing ANFOĪNFO ( / ˈ æ n f oʊ/ AN-foh) (or AN/FO, for ammonium nitrate/fuel oil) is a widely used bulk industrial explosive.
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