Ammonium nitrate prills

Frilling towers convert molten materials into droplets and allow them to solidify in contact with an air stream. Towers as high as 60 m are used. Economically the process becomes competitive with other granulation processes when a capacity of 200- 400 tons/day is reached. Ammonium nitrate prills, for example, are 1.6-3.5 mm dia in the 5-95% range. 

Ammonium Nitrate Prill and Fuel Oil Mixtures (AN/FO) available in 50- and 80-pound multiwall paper bags, packages from 5 to 12 inches in diameter, and in bulk deliveries to field storage bins or direct to the blasthole ... 

Ammonium nitrate prills are often mixed with fuel oil (liquid hydrocarbons) to produce a commercial explosive mixture known as ANFO which is used in quarrying. ANFO can be prepared in a factory by mixing both ingredients in a rotating container and dispensing the product into polyethylene or cardboard tubes. The tubes are then sealed and transported to the place of use. ANFO can also be prepared at the site where the explosive composition is to be used. Fuel oil is poured into a polyethylene bag containing ammonium nitrate and left for some time to allow the oil to soak into the ammonium nitrate. The ANFO mixture is then poured from the polyethylene bag into the hole (i.e. shot-hole) where the explosive mixture is detonated. 

EGDN — Ethylene Glycol Dinitrate MM AN — Mono Methyl Amine Nitrate AN — Ammonium Nitrate Prills FO — Fuel Oil No 1... 

Fertilizer grade ammonium nitrate prilled with fuel oil is generally used in the U.S.A. for making explosives other than permitted types (see Vol. HI). 

The density of the prills is reduced substantially when much evaporation occurs with 0.2-0.5% water in the feed, ammonium nitrate prills have a specific gravity of 0.95, but with 3-5% water it falls to 0.75. Prilled granules usually are less dense than those made by layering growth in drum or fluidized bed granulators. The latter processes also can make larger prills economically. To make large prills, a tall tower is needed to ensure solidification before the bottom is reached. The size distribution depends very much on the character of the atomization but can be made moderately uniform. Some commercial data of cumulative % less than size are ... 

PRILLS. Small, round, or adcular aggregates of a material, usually a fertilizer, that are artificially prepared, In tlie explosives field, prills-and-oil consists of 94% coarse, porous ammonium nitrate prills and 6% fuel oil,... 

One of the more critical feed properties in the case of ammonium nitrate prilling is the moisture content of the melt. Evaporation of the melt to nearly 100% solids produces hard, non-porous prills. Larger water contents yield porous, less dense prills. 

Mixtures of porous ammonium nitrate prills with liquid hydrocarbons, loaded uncartridged by free pouring or by means of -+ Air Loaders are extensively used under the name ANFO blasting agents. 

Two modern methods developed by Nitro Nobel in Sweden arc depicted in Figs 107 and 108. Portanol (Fig. 107) is a pneumatic ejector developed for the efficient charging of AN-FO made from ammonium nitrate prills. It is based on the ejector principle, that is. the blasting agent is sucked from the container and blown tluougJi a hose into the bore-hole,... 

The (hygroscopic) ammonium nitrate prills have to be posttreated to avoid caking... 

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