Sciencemadness Discussion Board - ammonium nitrate

ammonium nitrate

Vikascoder - 3-4-2012 at 07:21

hey guys
i have reacted ammonium hydroxide with nitric acid to make ammonium nitrate . but the problem i am facing is to extract it from the solution .i want to ask can ammonium nitrate solution be boiled down to extract ammonium nitrate from it or it will detonate.
i cant wait it to evaporate . please suggest a good way to extract ammonium nitrate from its solution. can boiling work please tell

virgilius1979 - 3-4-2012 at 08:58

Ammonium nitrate decomposes over 200C. I think if you carefully monitor the boiling temperature it shouldn't explode. I don't know the boiling point of the solution, but it should be safe <150C.
By the way, reacting NH4OH with HNO3 should be the way to get pure NH4NO3, but it's a waste of nitric ac. in my oppinion. Reacting Na or K nitrate with NH4Cl or (NH4)2SO4 (better because of lower solubility of Na and K sulfates) should be cheaper.

[Edited on 3-4-2012 by virgilius1979]

Vikascoder - 3-4-2012 at 09:12

Dilute Nitric acid works for this purpose and it is easily available to me than potassium nitrate and ammonium chloride. Getting nitric acid for me is very cheap

Adas - 3-4-2012 at 10:42

Ammonium nitrate itself will not explode, don't worry

AndersHoveland - 3-4-2012 at 10:58

Molten ammonium nitrate that has been heated to just below its decomposition temperature is about as sensitive to initiation as TNT. Perhaps some type of thermite core to first start melting and decomposing the AN, before the thermite burns down to an explosive charge, buried below, to cause detonation of the molten AN.

barley81 - 3-4-2012 at 11:01

To build off of Anders's point, I suggest reading the following web page:
http://en.wikipedia.org/wiki/Ammonium_nitrate_disasters
Use temperature regulation while heating the solution.

AndersHoveland - 3-4-2012 at 12:15

Boiling down a solution of ammonium nitrate will not have any danger of explosion. But if one forgets about it, and lets it boil dry, it will create a big cloud of fumes (mostly nitrous oxide, but also some traces of poisonous other oxides of nitrogen), and this could possibly start a fire. Best to do this on a hot plate outside.

Ammonium nitrate is a very stable compound. For most chemistry uses there is no explosive dangers. The only danger are when very large quanties are in an intense fire, or when several kilograms are detonated by another explosive.

[Edited on 3-4-2012 by AndersHoveland]

dann2 - 3-4-2012 at 14:32

I once read (in the bowles of the Interwebs) that the reason AN is so sensitive when held just at it's decompositon temperature is that all the gas bubbles being created throughout its mass, cause the melt to have a favourable density for explosion.
The melt would all have to be at a similar temperature I guess.

[Edited on 4-4-2012 by dann2]

caterpillar - 3-4-2012 at 14:33

Quote: Originally posted by AndersHoveland

Boiling down a solution of ammonium nitrate will not have any danger of explosion. But if one forgets about it, and lets it boil dry, it will create a big cloud of fumes (mostly nitrous oxide, but also some traces of poisonous other oxides of nitrogen), and this could possibly start a fire. Best to do this on a hot plate outside.

Ammonium nitrate is a very stable compound. For most chemistry uses there is no explosive dangers. The only danger are when very large quanties are in an intense fire, or when several kilograms are detonated by another explosive.

[Edited on 3-4-2012 by AndersHoveland]

That's true. I can only add something. I got AN as a fertilizer- it was granulated AN. To increase its sensitivity I melted carefully it and when portion of AN had been melted, I stopped heating and began to stir it. During intense stirring viscous liquid transformed to heap of crystals. Same op can be performed with Al if one wants to get powder- but it is not so easy.

Vikascoder - 3-4-2012 at 20:05

So means boiling on medium temperature will work without any problem thanks everyone .

Fossil - 4-4-2012 at 12:20

Quote: Originally posted by Adas

Ammonium nitrate itself will not explode, don't worry

Ammonium nitrate will deflagrate at roughly 200 degrees Celsius so there is cause to worry.

Berrilium - 4-4-2012 at 13:04

I recently boiled down about 250 ml saturated solution AN, it works best for me to boil it down until it is about the same colour as milk, then cool to 0 degrees C and removing solid AN (lots of it).

Vikascoder - 4-4-2012 at 19:02

Oh thanks everyone i was getting woried whether boiling it can destroy everything near it.

AndersHoveland - 7-4-2012 at 16:02

Quote: Originally posted by dann2

I once read (in the bowles of the Interwebs) that the reason AN is so sensitive when held just at it's decompositon temperature is that all the gas bubbles being created throughout its mass,

Perhaps, but another important reason is that ammonium nitrate is more of an entropic explosive, meaning that much of the explosive energy does not come from heat being produced, but rather from the decomposition products taking up a greater gas volume than the original solid. Pre-heating the ammonium nitrate to just below its decomposition point means less (additional) activation energy is required to make it decompose (or detonate). The additional heat could also help the decomposition gases expand, potentially making the explosion more powerful to some extent.

A truely pure entropic explosive would theoretically be unable to explode below the temperature that was the boiling point for its decomposition gases, for example if it was pre-cooled in liquid nitrogen. From one perspective, an entropic explosive can derive energy from the room-temperature heat contained within the initial solid.

Quote: Originally posted by Fossil

Ammonium nitrate will deflagrate at roughly 200 degrees Celsius so there is cause to worry.

Perhaps you meant "decompose" ?
Pure ammonium nitrate cannot deflagrate. Even mixtures of ammonium nitrate with fuels generally only burn with difficulty, this could hardly be called "deflagrate". Ammonium nitrate is one of those substances that can be detonated, but does not burn very well when it is acting as the oxidizer is normal combustion. Even potassium nitrate burns much better in deflagrating compositions. AN acts as a poor pyrotechnic oxidizer for two reasons, it absorbs a large quantity of heat before it can melt/decompose, which it must do before it can act as an oxidizer, and the oxidation of the ammonia in AN releases less energy than the oxidation of other typical fuels. So AN compositions are less energetic than potassium nitrate compositions, but AN contains the fuel and oxidizer in the same molecule, which is why AN can detonate, but generally potassium nitrate compositions cannot (this relates to surface area and reaction rate).

[Edited on 8-4-2012 by AndersHoveland]

Fulmen - 26-6-2012 at 23:53

Quote: Originally posted by AndersHoveland

So AN compositions are less energetic than potassium nitrate compositions

This is incorrect, AN-compositions are far more energetic than KN. The reason is simple, 40% of potassium nitrate is the inert potassium, so even with the reduced fuel value of ammonia AN still comes out far ahead. Then you have to consider the amount of solids produced by KN, while this doesn't detract from the energy content it reduces performance significantly.

AN-compositions are usually slow burning, but this is partly due to the high pressure exponent. Consider ammonpulver (AN/charcoal) which is claimed to perform almost as well as smokeless powder in high pressure rounds. Burn rate is also reported to be higher.

Ral123 - 27-6-2012 at 02:42

I often heat quantities of like 100g an to get N2O. The process is exotermic and I think AN can deflagrate at certain density under sertain pressure. I'm actioally wondering why AN compositions are so low on energy, volume based one liter of AN composition have as much HNO3 as MeNO3. AN is a big Choking Hazard and you should handle only in presence of adults.

Fulmen - 28-6-2012 at 02:13

Quote: Originally posted by Ral123

I'm actioally wondering why AN compositions are so low on energy

They're not. Of course it depends on what you're comparing it to, but the heat of explosion of ANFO is roughly 90% of TNT.

As for deflagration of AN, I believe it can happen in the molten state. In solids I doubt the energy of pure AN is enough to cause a runaway reaction.

AndersHoveland - 28-6-2012 at 05:07

Quote: Originally posted by Ral123

I'm actually wondering why AN compositions are so low on energy,

N-H bonds are stronger than C-H bonds, and the ammonium ion is even more stable. The nitrate ion is also very stable. If one looks at the resonance structure of the nitrate ion there are two negetive charges distributed around the three oxygen atoms (the central nitrogen atom has a positive charge).

If you want to think of it this way, a significant quantity of energy is released when ammonia is neutralised with nitric acid (in an acid-base reaction). So naturally there will be less energy available when the resulting ammonium nitrate salt later decomposes.

Goorlap - 28-6-2012 at 15:35

It's better to evaporate the water at low temperature, around 80° C for example

MR AZIDE - 28-6-2012 at 16:10

Last time I made AN, it was better to allow it to evaporate slowly-ish, using the low heat generated from a tea-light candle, in a large evaporating basin.
This was to maximize the surface area of the liquid to be evaporated while minimizing the depth of the solution to be evaporated, as opposed to trying to evaporate it in a small evaporating basin, which was barely big enough to contain all the solution.

Once most of the water is evaporated, the remaining specific heat capacity of the basin is usually enough to allow the evaporation to dryness, once the heat source is taken away.

Although some confusion can be had, if all the water has been driven off, and any of the AN melts.......this gives the appearance of the last bit of water still remaining, untill you realize the noxious fumes is the salt decomposing.

hyfalcon - 29-6-2012 at 03:25

My oven will go down to 170 F. That should be slow enough I would think.

bahamuth - 29-6-2012 at 05:50

Safest way is to evaporate in in a dish over steam from boiling water, takes time but won't decompose even if you fall asleep ,I did

. Additionally, it will stop to evaporate at some point since NH4NO3 is hydroscopic/deliquescent. At this point just cool down and needle like crystals will appear, and after a while the whole dish is solidified. The suction filter until dry, and if you wish or have the equipment, dry under high vacuum in a hot waterbath to get free flowing crystals. One may have to do some additional evaporating directly on the hot plate but very little and keep an watchful eye on the evaporating dish. This will give you less yield than total evaporation but of superior purity and of excellent crystalline structure.

Start of needle crystals of ammonium nitrate

More ammonium nitrate needles (got impatient so stirred the solution to induce more seeds for crystal formation).

Ammonium nitrate cystals after suction filtering until dry.

Never dry in an enclosed oven until dry as almost everything tend to sublimate more or less or fume when dry, additionally if you evaporate until dry you get every impurity with you, crystallization is way better. Total evaporation directly on a hotplate is also very bad even a thermo controlled one as one might get charring. I speak very generally of course, not just about ammonium nitrate.

siegfried - 11-9-2012 at 15:04

82g Ammonium Sulfate + 164g Barium Nitrate = 100g Ammonium Nitrate (theoretically)

(NH4)2SO4 can be bought on Ebay 500g (ACS) shipped $22, 1kg Reagent shipped $46 and 5 lbs Lab grade shipped $88

Ba(NO3)2 can be bought from Rolling Thunder Pyro for $5 a pound plus shipping. Evaporate the Ammonium Nitrate solution

A kilo of nitrate should work out to a cost of about $50. Surely it's available for less cost but a can't find a source

Kalium - 11-9-2012 at 15:32

Quote: Originally posted by siegfried

82g Ammonium Sulfate + 164g Barium Nitrate = 100g Ammonium Nitrate (theoretically)

(NH4)2SO4 can be bought on Ebay 500g (ACS) shipped $22, 1kg Reagent shipped $46 and 5 lbs Lab grade shipped $88

Ba(NO3)2 can be bought from Rolling Thunder Pyro for $5 a pound plus shipping. Evaporate the Ammonium Nitrate solution

A kilo of nitrate should work out to a cost of about $50. Surely it's available for less cost but a can't find a source

Instant cold packs are still a viable source. 1kg costs around $10. Some companies use ammonium nitrate that is almost pure and ready to detonate in prill form. However, you'd need to buy a few brands and test the contents as most have been forced to switch to urea.

NedsHead - 19-1-2016 at 04:59

Batch #2 of ammonium nitrate, HNO3 + NH4OH method.

[Edited on 19-1-2016 by NedsHead]

hissingnoise - 19-1-2016 at 05:45

Nice! Filtering the old CAN fertiliser was time-consuming and messier but the product was about the same!

Its cost, though, was altogether different . . .

NedsHead - 19-1-2016 at 06:07

I wish I had the option to to just grab a bag of CAN and filter it, I would even settle for a supply of nitric acid. I currently have to first make the nitric so I can then make the ammonium nitrate but it's also very time consuming.

I think I'll look for some other processes with OTC chems

Bert - 19-1-2016 at 07:17

Dedication...

Could you estimate hours of your time spent & actual materials cost per kg of finished AN?

Granted, equipment for making nitric acid and performing the metathesis reaction is minimal, but I have to think amateurs in a few countries WOULD be ahead to improvise a small Haber-Bosch plant- Bet THAT would surprise hell out of the judges at your local high school science fair!

Whip out your collection of Raspberry Pi and PID bits for process control and start fabbing. You'll need the school's art dept. ceramics kiln for firing the porous ceramic catalysts, and a bit of time in the metal shop for assembling the rest of the process equipment.

A school year should be enough? Then just wheel the unit into the science fair exhibition hall, plug the unit in, turn on the air compressor and natural gas supply. Stand back.

Anything worth doing is worth OVER doing!

NedsHead - 19-1-2016 at 15:24

Maybe I'll stop complaining and continue concentrating battery acid and distilling the nitric acid

it is a pain but I'm rewarded in the end. I'm considering buying a larger RBF so I can produce larger batches at one time, the largest RBF I own at the moment is only 1000ml and foaming prevents me from using its full capacity.

I haven't calculated the actual cost in materials, I buy in bulk so the costs are quite low.