From: AHAHMA%kontu.utu.fi@ssyx.ucsc.edu Subject: ANFO Date: 30 May 90 16:15:12 GMT >I have not dome any work don sintering/melting explosives. Does anyone have >experience with AN/FO mixtures, especially in confinement and initiation? ANFO must be either very tightly confined or used in big amounts to function properly. If not confined, the critical diameter for fertilizer (80 % AN) is about 5 to 7 cm. That means you have to take at least a sphere of 10 to 15 cm in diameter and place the detonator in the middle. In practice it means only charges over one kilogram work. And the detonator must be 20 grams of TNT or some more brisant explosive. If the ANFO is confined, the critical diameter is smaller and even charges under 0,5 kg can be detonated completely. Also the grade of the AN affects the initiation. The best is prilled (spray dried) AN, which has a large surface area and a lot of pores in the prills. If the AN is ground or dense particles, it will be much more difficult to ignite - like the fertilizer. The sensitivity can be increased with additives, such as nitroglycol, TNT, aluminum dust, other high explosives. Adding 4 % of EGDN will make any AN cap sensitive; the excess oxygen released can be used up by adding a solid fuel, for example carbon black or sugar. However, these mixtures are closer to dynamites than ANFO. ArNO 2