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Author: Subject: Ammonium nitrate anti cake for milling
Gargamel
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[*] posted on 6-6-2015 at 08:24
Ammonium nitrate anti cake for milling


My experience with milling AN is that it tends to cake when it is milled down.

Some lumps always avoid the blades of coffee grinders or kitchen blenders employed for the task, or stick to the ballmills walls.

Especially when it's not 100% dry, or the prills are waxed.


I found that with certain other crystalline materials anti cake helps a lot.
How about AN, what is your experience, what do you use and how much?

(I've got Silicon dioxide powder and I'd start with 0,5%)

[Edited on 6-6-2015 by Gargamel]
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MineMan
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[*] posted on 6-6-2015 at 08:33


Gargamel

You are awesome... because I was going to ask this question myself... so I am looking forward to answers everyone!

Even when I use a coffee grinder to grind Activated AN it still cakes.
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blogfast25
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[*] posted on 6-6-2015 at 08:44


MgO is often used as an anti-caking agent. Cheap, quite inert and non-hygroscopic.

Talcum powder is another. Very OTC.

[Edited on 6-6-2015 by blogfast25]




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Fulmen
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[*] posted on 6-6-2015 at 14:43


My experience is that many if not all dry, non-caking powders have an effect. Fumed silica (cab-o-sil or whatever) are often used, but anything that's compatible can be used. FOr instance KNO3 kan often be milled with a pinch of airfloat charcoal if it's to be used for pyrotechnics, and it really improves milling. Things like MgO might affect pH and/or reactivity, so first you should consider the final application. Anything inert should be fine of course unless you're looking for pure colors, in that case solids might cause them to wash out somewhat. .



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Rosco Bodine
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[*] posted on 7-6-2015 at 05:57


MgO will react with NH4NO3 to form Mg(NO3)2 accompanied by evolution of ammonia. At low moisture content it could work well as an anti-caking agent, but probably only up to a point of increasing moisture absorbed where it could cake again and maybe worse than would occur for the NH4NO3 alone.

One of the most interesting things I have found is the possibility of mixed nitrate eutectics which can form a melt at reasonably low temperature that can completely dehydrate as a eutectic mixture the usual highly hydrated nitrates that alone almost defy complete dehydration by heating even assisted by vacuum. Some of those eutectic melts will dehydrate completely but when cooled will set up as a solid monolithic glass. But there are variations on such compositions which will instead on cooling crystallize as a fine microcrystalline loose powder so that the result is a nitrate mixture having zero moisture that was "self milling" to produce a fine mesh anhydrous mixture of nitrates that is homogenous. Such mixtures could be useful as oxidizers in propellants or pyrotechnics, or could be useful in nitration schemes.
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Fulmen
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[*] posted on 7-6-2015 at 09:25


You are right, MgO is not well suited. I remember trying a mixture of AN and Mg/MgO/Mg(OH)2 once, it started reeking of ammonia pretty quickly. This was magnesium dust collected from a wet dust-collector connected to a belt sander for Mg-alloys...



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Gargamel
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[*] posted on 11-6-2015 at 10:37


Well, I've got some prilled fertilizer here, and it milled fine even without additional anti-cake.

Trying a second batch with added silicon dioxide behaved identically. What leads me to believe there already is something in there...

I dissolved some, result:
-very few white flakes swimming on top - paraffine or something.
-everything else is soluble
-no smell at all.

The supplier mentions there is Magnesium nitrate in there, and that this is for anti-cake purposes. So I think I got what is called "stabilized" AN.

I'll see how the milled powder behaves over time, would be really great if this actually keeps the powder shape in storage.
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[*] posted on 11-6-2015 at 12:47


http://www.ebay.co.uk/itm/Excalibur-E072-Food-Dehydrator-Sol...

What is a food dehydrator and could it be used for drying salts etc?
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Amos
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[*] posted on 11-6-2015 at 13:02


Quote: Originally posted by jock88  
http://www.ebay.co.uk/itm/Excalibur-E072-Food-Dehydrator-Sol...

What is a food dehydrator and could it be used for drying salts etc?


I think you answered the first question just by naming the device. It uses a stream of heated air to dry food. I actually have a cheap (~$35) one that I use all the time for chemistry. It's great for drying filter residues and crystals.




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