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Brightthermite
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Drying Chems without desiccator
I have been trying to dry around 200 grams of ammonium nitrate for going on 3 days now. I've been putting it in the oven in two separate glass dishes
at around 200 F with the door left cracked. I was driving water off for around 4 hours each day with no sign of it slowing down. I have around 5
pounds I need to re-crys and dry and in need of some help on how to go about this, the oven just is not working!
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B(a)P
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Get a large airtight container and place your product in there on a tray and next to it some anhydrous calcium chloride.
Edit - I assumed you meant without a desiccator because you did not want to buy a purpose built glass (expensive) desiccator. My point is you can make
one very cheaply with plastic storage containers and a product like DampRid or similar.
[Edited on 14-7-2020 by B(a)P]
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Brightthermite
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Quote: Originally posted by B(a)P  | Get a large airtight container and place your product in there on a tray and next to it some anhydrous calcium chloride.
Edit - I assumed you meant without a desiccator because you did not want to buy a purpose built glass (expensive) desiccator. My point is you can make
one very cheaply with plastic storage containers and a product like DampRid or similar.
[Edited on 14-7-2020 by B(a)P] |
Well I said no desiccator because I would like to dry it out within the day. However I may very well have to do what you suggested.
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Eddie Current
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I would personally caution against drying ammonium nitrate in an oven, and it is typically prepared by hot air tumble drying, so you need good air
circulation and agitation in this set up.
If you cant find a vacuum desiccator and it is suitable for your purposes then "Preparation of Ammonium Nitrate for Use as a Fertilizer" reports a
process where 95% NH4NO3 was blended with 5% CaSO4*0.5H2O (plaster or paris) resulting in a 95% decrease NH4NO3 moisture content.
https://naldc.nal.usda.gov/download/CAT86200904/PDF
The generic CaSO4*2H2O (gypsum) can be prepared by grinding it in to a fine powder then heating it in an oven to 150C (~300F), then blending it with
the NH4NO3.
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Brightthermite
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| Quote: Originally posted by Eddie Current | I would personally caution against drying ammonium nitrate in an oven, and it is typically prepared by hot air tumble drying, so you need good air
circulation and agitation in this set up.
If you cant find a vacuum desiccator and it is suitable for your purposes then "Preparation of Ammonium Nitrate for Use as a Fertilizer" reports a
process where 95% NH4NO3 was blended with 5% CaSO4*0.5H2O (plaster or paris) resulting in a 95% decrease NH4NO3 moisture content.
https://naldc.nal.usda.gov/download/CAT86200904/PDF
The generic CaSO4*2H2O (gypsum) can be prepared by grinding it in to a fine powder then heating it in an oven to 150C (~300F), then blending it with
the NH4NO3. |
I would like to keep my AN without contaminate, however I was not aware plaster of paris is so moister hungry, I have a lot of that lying around and
my use it in a desiccator set up. My I ask why you caution against oven drying besides the obvious of it getting to hot?
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Eddie Current
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It's just not a very efficient way to do it, and there are potentially dangerous aspects. In my experience, if people without proper training
continually take procedural short cuts, then they get more and more confident over time until finally something goes very wrong. I am an uber safety
person.
It appears from the literature that the NH4NO3 is difficult to dry in bulk amounts, at least that's my reasoning for the agitation in the commercial
drying systems, so if you're going to utilise a desiccator, then I would spread the salt out in a thin layer, dry it, store it sealed from atmospheric
moisture with a suitable desiccant, then continue doing these smaller batches until you have dried all of your salt.
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Belowzero
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I've had some success with ethanol.
Drying this material is a pain indeed, when the temp reaches above a certain point it becomes so soluable that it will dissolve itself even in tiny
traces of water , the effect is really pretty as it returns from solid to liquid in a flashing almost instant manner.
Of course the decomposition temp is so close that it will decompose even before the last water is driven off.
I figured alcohol could be useful to assist in driving off the remaining water.
The AN was placed in a steel container and slowly heated to roughly 100 degrees C.
With the remaining water present this turns into a thick liquid.
Ethanol was added in small portions which obviously instantly boils and forces the AN to crystalize upon contact.
While the AN was still slightly wet with alcohol the container was taken off the heat and placed under a high watt lightbulb covered with some
aluminium foil.
After a few hours the material was nearly dry and placed in an desiccator, overnight the material was perfectly dry.
This might not be the safest, especially the instant boil/crashing of the AN is violent , sending a mist of AN/water and ethanol into the air.
Take proper precautions.
I realize that mixing a hot oxidizer with a fuel is a bad idea from a theoretical point of view however I do not believe that this is actually likely
to lead to an explosion or combustion.
Bio ethanol comes quite cheap here, making this an affordable method.
In the past I used my car for drying materials, as funny as this may sound it was very effective, as you know a car in the sun can reach temp of 50
degrees C and beyond and with one window left open there is plenty of vapor pressure, also there is a relatively small amount of airborn dust. The
energy involved is remarkable and free.
[Edited on 15-7-2020 by Belowzero]
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Brightthermite
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| Quote: Originally posted by Belowzero | I've had some success with ethanol.
Drying this material is a pain indeed, when the temp reaches above a certain point it becomes so soluable that it will dissolve itself even in tiny
traces of water , the effect is really pretty as it returns from solid to liquid in a flashing almost instant manner.
Of course the decomposition temp is so close that it will decompose even before the last water is driven off.
I figured alcohol could be useful to assist in driving off the remaining water.
The AN was placed in a steel container and slowly heated to roughly 100 degrees C.
With the remaining water present this turns into a thick liquid.
Ethanol was added in small portions which obviously instantly boils and forces the AN to crystalize upon contact.
While the AN was still slightly wet with alcohol the container was taken off the heat and placed under a high watt lightbulb covered with some
aluminium foil.
After a few hours the material was nearly dry and placed in an desiccator, overnight the material was perfectly dry.
This might not be the safest, especially the instant boil/crashing of the AN is violent , sending a mist of AN/water and ethanol into the air.
Take proper precautions.
I realize that mixing a hot oxidizer with a fuel is a bad idea from a theoretical point of view however I do not believe that this is actually likely
to lead to an explosion or combustion.
Bio ethanol comes quite cheap here, making this an affordable method.
In the past I used my car for drying materials, as funny as this may sound it was very effective, as you know a car in the sun can reach temp of 50
degrees C and beyond and with one window left open there is plenty of vapor pressure, also there is a relatively small amount of airborn dust. The
energy involved is remarkable and free.
[Edited on 15-7-2020 by Belowzero] |
Its amazing to see just how much water is left in what appear to be dry AN!
Funny you mention the car, that is what my father suggested. Ill try that tomorrow. So far keeping my oven at 200 F there has been no noticeable
decomposition. I am going to try the ethanol approach as well. I believe I will dry during the day and place it in a desiccator over night.
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Tsjerk
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You can easily crank up the heat of the oven, and leave the door closed. Most ovens have air circulation so water will be driven off anyway.
Ammonium nitrate melts at 167 degrees Celsius and decomposes at 210. I remember oven drying it at around 120. First it will probably dissolve in its
own water, but when it solidifies again you know it is dry.
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Junk_Enginerd
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I've managed to dry AN quite well. I can't say for certain how much moisture was left since it wasn't critical for me, but it stopped being liquid
when heated, and burned decently when mixed with sugar, so that should say something.
I put it on the stove and kept it at roughly 150°C, as a liquid, and had a desk fan pointed at it. Eventually it solidifed and then I was happy. A
temperature regulated hotplate is of course preferable.
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Refinery
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How much faster is a vacuum desiccator compared to an NTP desiccator bag?
Does vacuum desiccation allow to remove hydrate water without heating?
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outer_limits
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According to this: https://www.tandfonline.com/doi/pdf/10.1081/JFP-100108655
Equlibrium in vaccum dessicator is established after 2-3 days instead of 2-3 weeks. Probably it doesn't fit to each case but vacuum dessication should
be much faster than performed at normal pressure
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Brightthermite
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Ive continued oven drying while I make the time to go pick up some DampRid and my AN has picked up some strange dark spots. I check the top of the
oven and nothing is dripping down on it. Any ideas?
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Belowzero
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| Quote: Originally posted by Brightthermite | | Ive continued oven drying while I make the time to go pick up some DampRid and my AN has picked up some strange dark spots. I check the top of the
oven and nothing is dripping down on it. Any ideas? |
My first guess would be decomposition of contamination.
In simpler terms; charring
How pure is your source and what did you do to purify ?
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Brightthermite
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| Quote: Originally posted by Belowzero | | Quote: Originally posted by Brightthermite | | Ive continued oven drying while I make the time to go pick up some DampRid and my AN has picked up some strange dark spots. I check the top of the
oven and nothing is dripping down on it. Any ideas? |
My first guess would be decomposition of contamination.
In simpler terms; charring
How pure is your source and what did you do to purify ? |
I cant speak for how pure my source is. It was purchased as "cold pack refills". Pretty sure its intended for exploding targets so I would say its
definitely not lab grade. I purified by dissolving and filter.
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Brightthermite
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This was what the bottom of the salt chunk looked like when removed from the glass dish. I am dissolving it in water now and going to re-crys it. It
is already developing a brown sediment covered foam. However if the contaminate is something other than just dirt any ideas how to remove it?
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Belowzero
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You could take advantage of the fact that AN is so soluable.
Use a minimum amount of water to dissolve it and filter.
Most other substances are not likely to dissolve so easily.
Washing with aceton or ethanol could improve purity since AN does not dissolve well in those and your contaminations might, since we do not know what
is in there this is just a guess.
For fertilizers they use some sort of clay perhaps to assist the creation of prills.
Since coldpacks are a bulk product too it is not unlikey they use the same supply chain.
It's a pain in the ass to filter as the clay/sand likes to clog up filters.
I did 2 rounds of crystalization to get a relatively pure product, this was fertilizer, probably worse than what you have.
You could also try to dissolve it and leave it to stand for a day or 2.
A layer of gunk may seperate which can be decanted or sucked out.
Makes filtering a lot easier too.
Also wet AN does seem to have a slight off-white appearance.
[Edited on 17-7-2020 by Belowzero]
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Brightthermite
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| Quote: Originally posted by Belowzero | You could take advantage of the fact that AN is so soluable.
Use a minimum amount of water to dissolve it and filter.
Most other substances are not likely to dissolve so easily.
Washing with aceton or ethanol could improve purity since AN does not dissolve well in those and your contaminations might, since we do not know what
is in there this is just a guess.
For fertilizers they use some sort of clay perhaps to assist the creation of prills.
Since coldpacks are a bulk product too it is not unlikey they use the same supply chain.
It's a pain in the ass to filter as the clay/sand likes to clog up filters.
I did 2 rounds of crystalization to get a relatively pure product, this was fertilizer, probably worse than what you have.
You could also try to dissolve it and leave it to stand for a day or 2.
A layer of gunk may seperate which can be decanted or sucked out.
Makes filtering a lot easier too.
Also wet AN does seem to have a slight off-white appearance.
[Edited on 17-7-2020 by Belowzero] |
Yeah that's how you can tell if it is truly dry, its bone white and looks like it will crumble. Im pretty sure those impurities are from using well
water instead of distilled.
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Psytophisque
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This might be overkill but could potentially solve your problem. Dissolve the AN in hot water and filter out the gross. Evaporate the water then add
the resulting solids to toluene and dry with a dean stark or clevenger (if you have these obviously though I am sure it can be done without the
specific glassware). AN isn't soluble in toluene but the boiling should still pull off the water and most organic contaminants will likely dissovle in
the toluene which you can (and should) distill to recycle anyway. Once no more water is coming off vacuum filter and pump dry or gravity filter and
fan dry before overnight dessication in a plastic food container with your favorite dessicant (I use two smaller containers in a larger one with NaOH
in one and CaCl2 in the other) just to be sure the last of the water is gone and also to keep it dry until you are ready for it. I haven't tried this
but I imagine it might work, good luck!
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Brightthermite
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| Quote: Originally posted by Psytophisque | | This might be overkill but could potentially solve your problem. Dissolve the AN in hot water and filter out the gross. Evaporate the water then add
the resulting solids to toluene and dry with a dean stark or clevenger (if you have these obviously though I am sure it can be done without the
specific glassware). AN isn't soluble in toluene but the boiling should still pull off the water and most organic contaminants will likely dissovle in
the toluene which you can (and should) distill to recycle anyway. Once no more water is coming off vacuum filter and pump dry or gravity filter and
fan dry before overnight dessication in a plastic food container with your favorite dessicant (I use two smaller containers in a larger one with NaOH
in one and CaCl2 in the other) just to be sure the last of the water is gone and also to keep it dry until you are ready for it. I haven't tried this
but I imagine it might work, good luck! |
Thank you for the idea! Once my proper glassware arrives I am going to try something just like this. Ive put the whole process on hold as it was to
humid to use my car to dry it (It came out more soaked then when I put it in there!). Does anyone have any experiences using a jerky dehydrator to dry
things?
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Fyndium
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Someone mentioned CaCl2 absorbs also ethanol and acetone. Does this apply and can it be used to dry reagents from other solvents too, apart from water
content?
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Fyndium
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I thought how could I heat a desiccator bag setup.
I took the infamous blue coffin of the deschem which is made of urethane, an excellent insulator and put a trash bag in it and filled it with hot
water and placed the plate inside a transparent trash bag over the box with CaCl2 desiccant. It gently heats up the moist powder and evaporates the
water and ethanol a lot faster than in ambient temp.
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TriiodideFrog
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You can simply put the ammonia nitrate in a bowl in a large ziploc and place anhydrous calcium chloride, silica gel or sodium hydroxide around it.
This method worked when my desiccator broke.
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Fery
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If you obtain NH4NO3 from fertilizer where it is mixed with CaCO3/MgCO3 then it is contaminated with Ca(NO3)2 and Mg(NO3)2 - both are much more
hygroscopic than NH4NO3.
Did someone observe that already dry NH4NO3 absorbed moist from the air due to Ca/Mg contamination?
It could be get rid of Ca/Mg contaminants by adding little of (NH4)2CO3 or few drops of aqueous NH3 and there is always some CO2 in water absorbed
from air and finally filtering the CaCO3/MgCO3 precipitate.
My second idea was drying NH4NO3 and then recrystallization from ethanol (only theoretical idea, never tried it practically).
http://periodic-table-of-elements.org/SOLUBILITY/ammonium_ni...
solubility in ethanol: 2,5 (20 °C), 5 (40 °C), 7,5 (60 °C)
I would very probably cool down to 0 C but I did not find solubility at such low temperature, and of course I wouldn't waste anhydrous ethanol for
that and use 96% in which the solubility would be very likely somewhat higher.
http://www.sciencemadness.org/smwiki/index.php/Calcium_nitra...
Solubility in ethanol:
51.4 g/100 g (20 °C)
62.9 g/100 g (40 °C)
I remember from old cz pyro forum that one guy (IIRC he used there a nick Cyano?) dissolved granules of fertilizer in water and let it to sit in PET
bottle for few days to settle the fine dust of CaCO3/MgCO3 and then used hot nail to make a small hole in the side wall of the flask at slightly
higher position than the border of the settled dust and let the clear liquid to flow out as filtering the fine dust from fertilizer was painful.
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chemist1243
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Have you tried a food dehydrator? I have one I use a lot to dry small amounts of chemicals very quickly, but i bet you could fit a few hundred grams
of material in one and dry it out in a few hours. I havent tried it on ammonium nitrate, but I dont see why it wouldnt work.
[Edited on 10-3-2021 by chemist1243]
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