Grinding method 1

How to pulverize large quantities of ammonium nitrate prills/granules

Size of prills matter

Mixing AN with fuel

A more common and almost as effective method of mixing is by uniformly soaking prills in opened bags with 8 to 1O percent of their weight of oil. After draining for at least a half hour the prills will have retained about the correct amount of fuel oil.

The fuel will disperse relatively rapidly and uniformly. Inadequate priming imparts a low initial detonation velocity to a blasting agent, and the reaction may die out and cause a misfire. So ensure a large enough booster/blasting cap.

Place the AN into the waterproof container. Sprinkle the diesel fuel onto the AN. Do not “stir” these materials, as that will cause them to pack together. Let stand for 1 hour. Seal the waterproof container.

Note: if powdered AN is being used and it becomes packed, it may be fluffed by ruffing a handful back and forth across a piece of screen or a cheese grater. If AN prills are used (compared to powdered AN) a larger booster charge must be used. Finally, ANFO charges must be at least 5 cm in diameter or they will not detonate properly.

However, there is usually little you can do about this fact, with the exception of choosing to powder the AN. In the mining industry, the term ANFO specifically describes a mixture of solid ammonium nitrate prills and No. 2 fuel oil (heating oil.) In this form, it has a bulk density of approximately 840 kg/m3. The density of individual prills is about 1300 kg/m3, while the density of pure crystalline ammonium nitrate is 1700 kg/m3. It is notable that AN prills used for explosive applications are physically different from fertilizer prills; the former contain approximately 20% air. These versions of ANFO which use prills are generally called explosives grade, low density, or industrial grade ammonium nitrate. These voids are necessary to sensitize ANFO: they create so-called "hot spots".

For small quantities you may simply use a wood roller, the wooden kitchen tool used for rolling dough, on a wood base. However, if you want to pulverize large amounts of AN, 100 kg+, you want to use more advanced methods.

Commercial coffee grinders: dedicate one grinder for use on oxidizers. We don't want fires or explosions when we're grinding chemicals. Never grind complete or mixed compositions such as black powder in a coffee grinder. The AN should not react with any material in the grinder as long as you use steel blades.

I have found two kinds of coffee grinders: blade-grinders and burr-mills. Don't get a burr-mill; they don't work as well as blade-grinders (at least not for coffee beans, perhaps for AN prills). The blade-grinders have a stainless steel blender type blade that spins at high speeds in the bottom of the material cup, pulverizing the material in the process. When evaluating whether to use a smaller, less expensive, blade-type coffee grinders; know that they really don't last too long if you mill chemicals for a minute or two at a time. To use them, mill your chemicals in pulses of a few seconds at a time. Shaking them while pulse-grinding can give you even faster results. There are different types of coffee grinders. You may want to choose an espresso variant as it will produce a finer powder. However, expect this factor to result in a doubled grinding time.

Be careful of heat buildup. Avoid aluminium blades, use steel blades (it’s usually steel as default). Avoid sparks. Quickly put in airtight container as powdered AN absorb water from air.

Grinding speed; depends on grinder. I did find an example from a commercial espresso grinder:

57 g in 20 seconds which equals 171 g per minute, 10,26 kg per hour. With this speed it would take 97,5 hours to grind 1000 kg of AN prills/granules. However, if you use a grinder constantly then expect it to only last a few hours. So you will probably need up to 10 grinders for 1000 kg prills. Expect the total amount of hours to exceed 200 hours as you don’t want the grinder to overheat. I heard that Baader, the Marxist scumbag from Red Army Fraction bought tens of grinders as they regularly broke down. He even bought a really expensive one but that one broke down as well. They ended up using wood rollers resulting in limited amounts of end product.

Prices range from 30 Euro up to 800 Euro.

Дата добавления: 2015-05-31