Rock ammonium nitrate explosive

No. 2 rock ammonium nitrate explosive (ammonium nitrate TNT wood flour = 83.5-86.5 10.0-12.0 3.5-4.5, mass ratio). 

The addition of aluminium to increase the heat of the explosion and, in consequence, the power of the explosive, as practised for some time, is now believed to be too dangerous. Ammonium nitrate explosives with aluminium are permitted only for rock work in opencast mining (e.g. quarries) or underground, where there is no methane. 

Ammonium nitrate explosives, both rock and permitted types, do not differ from those generally used in Central Europe. 

The simplest and most widely used ammonium nitrate explosive is the ammonium nitrate/fuel oil mixture (ANFO). This material has long been a staple for miners and quarry workers because it is very cheap, and because the low rate of detonation characteristic to it produces a breaking and heaving effect upon the rock in which it is placed. They prefer this result over the great masses of pulverized rock which would be produced had a more brisant explosive been used. 

The proper containers for all ammonium nitrate explosives are plastic, rock, or aluminum. Contact with copper or brass is especially dangerous If a brass detonator is only in contact with the booster charge, this precarious situation may be tolerated in... 

Many plants outside of North America pfill or granulate a mixture of ammonium nitrate and calcium carbonate. Production of this mixture, often called calcium ammonium nitrate, essentially removes any explosion hazard. In many cases calcium nitrate recovered from acidulation of phosphate rock (see Phosphoric acid and the phosphates) is reacted with ammonia and carbon dioxide to give a calcium carbonate—ammonium nitrate mixture containing 21 to 26% nitrogen (23). 

It is strongly recommended that our procedure1 not be used to prepare guanidine nitrate. Mixtures of ammonium nitrate and organic materials not much different from the mixture in the procedure are now used extensively as commercial explosives. The aqueous mixture of Note 101 is similar to some aqueous mixtures used in sizable quantities for rock blasting a confined mixture of this sort is especially hazardous. Only a few laboratories devoted to explosives research have the barricades and remote control devices needed to run this preparation of guanidine nitrate without risk. 

In an operation of this sort, the commonest explosive used is an ammonium nitrate gelatine such as Polar Ammon Gelignite. The wedge holes are likely to contain about 1 kg each of explosive and the other holes less than half this amount. The appropriate charge is usually calculated according to the nature of the rock, varying from 1 to 4 kg per m3 of rock between the softest and the hardest strata. 

In general, improvised explosives are too complicated to prepare or too weak for steel cutting and most other sabotage tasks. However, if the problem is to get a quantity of lower velocity explosive for cratering or moving a large volume of earth or rock, a good simple one can be prepared from ammonium nitrate fertilizer. 

Civil explosives are further sub-divided into permitted or permissible explosives and non-permitted explosives. Two types of civil explosives namely ammonium nitrate-fuel oil (ANFO) and emulsion explosives dominate the rock blasting scene in the USA. 

Type I—dynamites and rock explosives. The chief ingredients of the latter are ammonium nitrate, nitroglycerine and TNT. Their rate of detonation at a density of 1.1 is about 3800m/sec, their transmission distance 6 cm. 

Recently rock explosives mainly for use in opencast mining, composed of ammonium nitrate with fuel oil (as invented in the U.S.A. see p. 482) were introduced in Japan. 

In the U.S.A. in 1956 a new class of rock explosives was tried for the use in opencast mines, based on a patent taken out by Lee and Akre [88]. They are low cost explosives composed of ammonium nitrate and an inexpensive fuel such as carbon black. Rapid development took place in 1957-58 and their use was extended to certain underground operations. Fuel oil was next used as a combustible ingredient (AN-FO) explosives. 

AN-FO explosives are approximately twice as cheap as the usual ammonium nitrate rock explosives and three times cheaper than dynamites. 

Many permitted explosives are ammonium nitrate in powder form or gelatinous explosives with added inert salts such as rock salt or potassium chloride which reduce their explosion temperature. 

Acidic mine drainage from waste rock heaps and residues from ammonium nitrate-fuel oil (ANFO) explosive used for rock blasting... 

Safety explosives for mining are produced from anuuonium nitrate. Owing to its low explosion temperature in mixtures with NaCl, the temperature is not high enough to set off the much-feared firedamp. For greater explosive power, for example, for mining (rock explosives), porous-priUed ammonium nitrate containing approximately 6% diesel oil is used. 

Ammonium nitrate is used commonly in fertilizers in pyrotechniques, herbicides, and insecticides, as well in the manufacture of nitrous oxide. It is used as an absorbent for nitrogen oxides, an ingredient of freezing mixtures, an oxidizer in rocket propellants, and a nutrient for yeast and antibiotics. It is also used in explosives (especially as an oil mixture) for blasting rocks and in types of mining. 

The value for the ratio of burden to hole diameter, for average rock using an explosive such as ammonium nitrate-fuel oil (ANFO), has been suggested as 25 (Hustrulid, 1999). The spacing of the blast holes will be related to burden by an empirical ratio. The Atlas Powder Co. has suggested that the spacing should be between 1.0 and 1.8 times the burden. 

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