Crystaline AN.

[DBSP]

I think I've read something about this but I can't find it, I've looked in both the archive and on the forum.

Anyway I decided to see how much contaminents there was in my FGAN.
I turned out as I thought, lots of shit. I tried filtering the magnesium carbonate and the other additives away but the filter got useles in a few seconds since the sludge stopped the pores from letting the liguid through.

I let it stand untill the contaminents had setteled and then poured the liquid inta a boiler and started boiling the water off. I remembered something about recrystalizing the AN by cooling and filled a shotgun shell with the quite concentrated AN-liguid and put it in the freezer. When I had a look at it the shell was full of long beatiful needle crytals. I instantly fell in love with them :) .

If I remember correctly prills are better than powder and crystaline AN is better than prills. What kind off compositions are the cryst. AN best suited for? They seem to withstand moisture better than normal AN since the cystals dried by them selves.

What is the best way to get cryst. AN? I tried recrystalizing from ethanol but the result wasn't as good as with water. Since the density of the crystals is lower than the other forms of AN it shuld be more sensitive.

I appologise if this has allready been covered but I couldn't find anything but a few lines in a AN topic. BTW I couldn't access some of the archives.

[10fingers]

Crystallization from methanol works pretty good.

[CyclonitePyro]

I don't know the whole purpose of putting it in a shotgun shell. I only use AN in crystaline form for ANNM and other AN mixtures. I take my prilled AN from pyrotek, even though I specified on the phone for powdered. I powder the prills with a coffee grinder so that it dissolves faster. I put hot water in a large plastic container and dissolve the AN in it. Then I put the container in a food dehydrator, just a type of enclosed plastic case with a heating element on the bottom, and wait a couple of days and break up the crystals every once in a while. This seems to make much more sensitive ANNM.

For ANNM and related explosives, not ANFO, powder is better than prills and crystals are better than powder. Prills are good for ANFO, and ANSOY.

[Polverone]

Since my NH4NO3 came as a large, cheap sack of prills, I don't worry too much about losing some in the purification stage. Just make a hot saturated solution and let what crystallizes come out... They are pretty pure, these prills, certainly good enough for explosives. But they have just a little bit of greasy/oily contaminant that I can get rid of by recrystallization, and that's what I do for the stuff I'm going to use in the lab (as opposed to just in explosives/pyro).

Speaking of Pyrotek, they seem kind of incompetent, even if their shipping/sales policies are among the friendliest around. I ordered (among other things) a pound of sodium nitrite from them and they sent me sodium nitrate instead, but still charged the higher sodium nitrite price. They labeled the ziploc it came in as "sod nit". If they use 3 letters from each word in a chemical's name, no wonder they screw things up. At least it was easy to tell what the "pot perc" was. If it's really a pain to write full names they should just put the chemical formula on each bag.

[CyclonitePyro]

I just bought a 50lb bag of ammonium nitrate for $10 and another 50lb bag of potassium nitrate for 14. :D Both seem to be pure, after dissolving there is almost no powder in the solution not dissolved, I called the KNO3 company and some lady told me there is a 0.6% chlorine content, I guess that is the small amount of undissolved powder. I now pour the water as the solvent into a glass baking dish, it's my mom's, I guess for cakes, then add the KNO3 or NH4NO3, and put it on my hotplate and evaporate most of the water until I get a wet mass of crystals then I put those into my dehydrator. Tonight I let a half kilo of the NH4NO3 dissolved in 500ml of water evaporate on the hotplate too long and when I checked on it the basement slightly cloudy from some sort of smoke or mist that was odorless. This happened before with NH4NO3 to me. My hotplate only gets to a little hotter than 100C, how can it decompose then? What is the mist, or smoke? N2O? :)

[kingspaz]

the chlorine content would be soluble chloride impurities such as KCl and NaCl.

[CyclonitePyro]

Thanks for the info. I think my hotplate gets a lot hotter than the 100 C I thought it did.

[wrench352]

I tried last night to crystalize some AN.I took 3lbs AN,added 500ml water and heated to 175C.The AN were prills from ice packs I presume to be 100% AN.After a short while the prills turned to complete solution and steamed profusely.I let this go on for about 4hrs the solution began to darken,and maybe(eek)smoke alittle.At this point I turned off the oven,vented heat to 125C and went to bed.In the morning I had a 13 x9 3/4 brick of AN.On intialial inspection I felt as thoght the interior was "striated"(the presence of crystals)but now under closer examination it seems very similar to chalk.Okay,under close examination at one angle the an appears chalky,at slightly different angle,striated(wishful thinkin?).It is very similar in hardness and appearance to chalk.I broke the brick up into chunks and cuisinarted this to a fine powder.Any comments?

[ALENGOSVIG1]

You heated all the water off, and melted the AN. Not exactly recrystallization...

[wrench352]

Ok,for anyone interested melting point of AN= 169 C.Im gonna try this again at 75C on a coffee pot heater.

[wrench352]

Well after several tries I have come to the conclusion that,I personally cannot crystallize AN via heating.Every time I tried, I managed to melt it.I had read somewhere that someone had luck using a hair dryer.After giving this a go,it was a time consuming process and I was just not happy with the results,fluffy,white granules probably from the hairdryer interrupting the crystalization process.Im too much a stickler for esthetics soooooooo.
During the hairdryer experiment,my ol lady brought up the food dehydrator aspect,but Im chaeap and its too close to Christmas.BUT
In my smaller bathroom on top of the toilet I put a 1500watt heater,next to that on the sink a small oscillating fan (12in) and barely runnin,but good enough to circulate the air.A very small trial produced the needle crystalls in minutes,yes thats right minuits.Yee fuckin Haw!!!!!
Also for those interested this would also be a good way to dry your weed,this is where we basically got the idea,so mad props to my great ol lady and High Times.

[matjaz]

If you're happy with around 80% yield, try "my" method: The drastic temperature dependence of AN solubility in water helps a lot.

I pour 500ml of water into a 1l dish, fill with fertilizer prills to the top. Heat while stirring until the temp. is ~90C. Heating just beforehand is not enough since dissolving cools down the solution a lot. Keep it hot and let most of the mud settle to the bottom (takes a few minutes). Pour the solution into another dish. Typically, one or two more iterations will be needed to saturate. You're done when the prills don't dissolve anymore at 90C. Let it settle again and decant the (still hot) liquid thru a cloth. (You can use the microwave for heating, just stop it every minute or two and stir well to get the prills in touch with the less saturated part of the solution.) A little bit of ammonia gas will form while dissolving - air your room.

In winter time, just put the liquor outside. Otherwise, let the solution cool to room temp then put it in the freezer for a half an hour. The dish will be full of long needle-like crystals, just pour off the weak solution while still cold. You're left with 500-800g of AN. Put it on a hot something to dry. I get a beautiful snow white product by this method.

[CommonScientist]

CyclonitePyro - "I just bought a 50lb bag of ammonium nitrate for $10 and another 50lb bag of potassium nitrate for 14. "

I am extremely jealous of you! lol, I got about $25 and I think I should have someone else buy/obtain my AN for me, I know some farmer friends, and its a lot easier to "obtain" a 50lbs. bag of AN fert, than to buy a shitload of coldpacks. Although, The coldpacks I use have crystal form AN in them. Hmmm. I guess I will be needing my map soon : )

[Mendeleev]

I am trying to purify ammoniun nitrate fertilizer, the home depot 34-0-0 "All Purpose". I don't care about all the salt and wax impurities they are minimal and insignificant, however the fertilizer is full of small stones, and these are a pain in the ass. I don't really care about recrystallization, I just need pure AN, so I dissolved it in hot water, filtered through an old tee-shirt, discarded the stones and proceeded to boild of the water on a hot plate. I dissolved about 10kg of AN, so I have a lot of water to boil off, but it seems to be working, except I am noticing a slight ammonia smell. This tells me that my ammonium nitrate is decomposing, which it shouldn't be, because there is still a shitload of water and my hot plate is on relatively low power, could anyone tell me what the hell's going on?

[Kriegsminister]

I experienced this the same thing when I left the AN solution on the plate for too long. Except that the solution had already turned somewhat brownish and the kitchen was filled with white smoke.
Now I usually pour the AN solution into a shallow dish and place it on the radiator. It'll take some time but after a few day the AN will start crystalizing. I then use a heating fan to completely dry the AN. The advantage of this method is that you don't have to constantly watch the heating of the AN solution. Just let it sit and wait a few days...

[Mendeleev]

If I proceed to boil down the water anyway, despite the ammonia smell, will I get significant losses in ammoniun nitrate? Also, how high will the yields be if I decide to recrystallize? I have sort of a large batch, about 10 kg, so I am hesistant to try anything for fear of losing my AN. Also does anybody know why it's decomposing, It's probably no more that 100 degrees Celsius, and even so its in solution. I am confused.

[tmp]

The method I use is similar to Matjaz's. It takes advantage of the wide range
of NH4NO3's solubility. Solubility in 100 ml water: 118.3 grams at 0C,
871 grams at 100C. This according to CRC 52nd Edition 1971-1972. I put my
AN in boiling water until no more dissolves. Filter hot and place in the freezer.
The needle like crystals form almost immediately as the temperature drops.

[matjaz]

Mendeleev,

BOILING
it down doesn't work well. The solution doesn't boil at 100~C like water, I have measured temperatures over 120~C then trying this. The worst part is that the boiling solution will make a very smooth transition to molten AN with little water, eventually reaching 200~C, with hotter spots on the bottom of the pot, and in this state will eventually decompose if heated further. It can even detonate spontaneously when this hot.

TEMPERATURE
If you don't have a thermometer, blow gently over the surface of the solution (wear safety goggles here!). If you can see a gentle crystalline skin forming on the surface, you're more or less done heating. Another option: HDPE (film cans) melts at 130~C. Make a tiny cup out of Al foil, put a piece of HDPE in it, hold with pliers and touch to AN solution surface to see if HDPE melts.

YIELD
If you decide to recrystallise, the yield can be derived from the previous post (by tmp). 100g of water will dissolve 871g of AN at 100~C. Chill down to 0~C and only 118g of AN remain in solution, dumping 871g-118g=753g of crystals. That's 86% yield. You can do even better since you can heat this solution over 100 and chill it below 0.

AMMONIA
As for the ammonia smell... even in a cold solution you can smell it. That's OK. AN solution is just a lot of NH4+ ions and NO3- ions in water. Every now and then, an ammonia ion on the surface decides to rid itself of a proton and fly into the air. So in a way it "decomposes" already when dissolving.

[nbk2000]

I used to purify the prills by first swishing with water to remove the clay coating, using enough water to just cover the prills and letting it sit for a bit to settle, and scooping out the clean prills from the sludge on the bottom.

The water will get very cold while this is happening.

Then the cleaned prills would be dissolved into boiling water and the solution reduced till a crust formed. The still hot solution was poured into a pre-heated pyrex dish and set into an oven at 300°F, and left till it formed a powder. It would release faint white fumes at the end of the heating.

Occassional stirring of the heated powder in the oven was required to prevent clumping.

Once sufficiently dried, the oven was turned off and the powder left to cool slowly in the oven, being stir frequently while cooling and, while still hot, put up into a pre-warmed glass container and sealed up.

I reduced a kilo or so of AN in about 12 hours this way (mostly waiting), and it was flour fine and snow white. Even after months, it still stayed fluffy. :)

[Wild Catmage]

From what I've been taught, a mixture of two miscible liquids e.g. water and alcohol will boil at the average of the boiling points of its components. However the component with the lowest boiling point will start evaporating before the combined temperature is reached.

AN boils at 210 ºC and water at 100 ºC, so a mixture of both should boil at 155 ºC. However, as the water is lost during heating, the temperature will rise as the remaining solution becomes saturated and pure AN is left behind (there may be a flaw in this explanation).

A mixture of two immiscible liquids e.g. water and oil will boil at a temperature lower than the boiling point of the most volatile component.

[Mendeleev]

Wow, nbk that seems like really good method for high quality powder AN, however 1 kilo in 12 hours is bit to much wait for me. I decided to take the advice on recrystallizaiton yesterday and dumped the remnants of the fertilizer bag into the stockpot, which was heated to 95-100 Celsius. The bag claimed 18 kg of fertilizer, about one third of the weight was small stones, so that leaves me with about 12 kilos, given my losses and imperfect procedure I am estimating I extracted about 10 kg of ammonium nitrate. Last night it was kind of funny, my entire freezer was full of pots with super-saturated ammonium nitrate solution. This morning, they were crystallized cakes and I have just dumped all of the water out of the cakes, and am waiting for them to dry. The coolest one was in the shallow frying pan it looks like a 40 cm apirin tablet except with lots of striations. I took pictures, however I am on a bad computer right now, so I may try uploading them in a couple of days.

[ikbendirk]

i can't understand why everyone is making such a problem about recrystallising AN;

my method works as follows:

I dissolve the fertiliser prills (MgCO3,NH4NO3) in water.
i filter the MgCO3 off, and repeat this a while. Do not forget that AN is one of the most sulable salts in water: 100ml water can solute up to 215 grams of AN, so don't use too much water.
after that, filter the final remainder of the MgCO3, and you'll have a clear AN-solution

now this is where the magic takes place:

i put the solution on the radiator and let it sit a day or two for the water to evaporate, et voila :)
nice, rather big crystals with a nice odeur.

The package told me that the fertiliser only contained MgCo3 and NH4NO3, and some additional minor contaminents, but no significant amounts.
so i guess it should be quite pure AN now :)

[vulture]

From what I've been taught, a mixture of two miscible liquids e.g. water and alcohol will boil at the average of the boiling points of its components. However the component with the lowest boiling point will start evaporating before the combined temperature is reached.

AN boils at 210 ºC and water at 100 ºC, so a mixture of both should boil at 155 ºC. However, as the water is lost during heating, the temperature will rise as the remaining solution becomes saturated and pure AN is left behind (there may be a flaw in this explanation).


Since when is AN a liquid? A solution of a solid in a solvent will always have a higher boiling point and a lower freezing point than the pure solvent.
The solid will not evaporate as it is not volatile.

Even for a mixture of 2 liquids this is not always true. Many compounds form negative or positive azeotropes.

A mixture of two immiscible liquids e.g. water and oil will boil at a temperature lower than the boiling point of the most volatile component.

No, they'll behave as 2 pure liquids, eg the oil will boil at its normal boiling point and the water will boil at its normal boiling point.

[Mendeleev]

Allright, I finally got to a good computer with good photo software. This is the pick of one of the AN cakes I recrystallized from the 18 kg fertilizer bag, only 12 kg of which was AN. There were three more cakes at least as big if not bigger than this one :).

[Marvin]

Quote:
A mixture of two immiscible liquids e.g. water and oil will boil at a temperature lower than the boiling point of the most volatile component.


No, they'll behave as 2 pure liquids, eg the oil will boil at its normal boiling point and the water will boil at its normal boiling point.


Actually vulture he was right. For immiscable liquids the vapour pressures behave seperatly, but that doesnt mean the boiling points do. Becuase they behave seperatly, the vapour presures add (because one is not dependant on the other). This makes the total vapour pressure higher than it would be individually, and boiling happens when the total vapour pressure exceeds atmospheric. So the boiling point is lower, and the proportion of each chemical in the vapour/condensate is the same as the ratio between the vapour pressures of the substances in the pure state at the same temperature.

The same effect is what makes steam distillation work in organic chemistry.