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ANFO (or AN/FO, for ammonium nitrate/fuel oil) is a widely used bulk industrial explosive mixture. It consists of 94% porous prilled ammonium nitrate (NH4NO3) (AN) that acts as the oxidizing agent and absorbent for the fuel and 6% number 2 fuel oil (FO). ANFO has found wide use in coal mining, quarrying, metal mining, and civil construction in undemanding applications where the advantages of ANFO's low cost and ease of use matter more than the benefits offered by conventional industrial explosives, such as water resistance, oxygen balance, high detonation velocity, and performance in small diameters. It accounts for an estimated 80% of the of explosives used annually in North America.〔〕 The press and other media have used the term ANFO loosely and imprecisely in describing IEDs, in cases of fertilizer bombs. The use of ANFO originated in the 1950s.〔(Encyclopædia Britannica )〕 ==Chemistry== ANFO under most conditions is blasting cap-insensitive, so it is classified as a blasting agent and not a high explosive;〔(【引用サイトリンク】title=Explosives and blasting agents )〕 it decomposes through detonation rather than deflagration with a moderate velocity of about 3,200 m/s in diameter, unconfined, at ambient temperature. It is a tertiary explosive consisting of distinct fuel and oxidizer phases, and requires confinement for efficient detonation and brisance. Because it is cap-insensitive, it generally requires a primer, also known as a booster (e.g., one or two sticks of dynamite is historically used, or in more recent times Tovex or cast boosters of pentolite (TNT)/PETN or similar compositions) to ensure continuation of the detonation wave-train.〔(【引用サイトリンク】title=Explosives - ANFO (Ammonium Nitrate - Fuel Oil) )〕 The chemistry of ANFO detonation is the reaction of ammonium nitrate with a long-chain alkane (CnH2n+2) to form nitrogen, carbon dioxide, and water. In an ideal stoichiometrically balanced reaction, ANFO is composed of about 94.3% AN and 5.7% FO by weight. The normal ratio recommended is 2 U.S. quarts of fuel oil per 50 pounds of ammonium nitrate (80 ml/kg). In practice, a slight excess of fuel oil is added, i.e., 2.5 to 3 quarts of fuel oil per 50 pounds of ammonium nitrate, as underdosing results in reduced performance while overdosing merely results in more post-blast fumes.〔 When detonation conditions are optimal, the aforementioned gases are the only products. In practical use, such conditions are impossible to attain, and blasts produce moderate amounts of toxic gases such as carbon monoxide and nitrogen oxides (NOx). Variants of ANFO using diesel fuel, kerosene, coal dust, racing fuel, or even molasses in place of the red diesel (Nº 2 fuel oil) have been used as a source of carbon, and finely powdered aluminium in the mixture will sensitise it to detonate more readily. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ANFO」の詳細全文を読む スポンサード リンク
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