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Author: Subject: Calcium Ammonium Nitrate to Sodium Nitrate to Nitric Acid
artemov
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[*] posted on 28-10-2019 at 01:28
Calcium Ammonium Nitrate to Sodium Nitrate to Nitric Acid


I want to make azeotropic nitric acid by using calcium ammonium nitrate (15.5-0-0 fertilizer, the seller claims it's pure calcium nitrate however).

I intend to convert the calcium nitrate part to sodium nitrate first using sodium carbonate (converted baking soda)

5Ca(NO3)2.NH4NO3.10H2O + 5Na2CO3 -> 5CaCO3 + 10NaNO3 + NH4NO3

How should I deal with the ammonium nitrate part? Should I leave it be, or convert it to ammonia using NaOH or Na2CO3, before converting the whole lot to nitric acid using sulphuric acid?

How would aqueous ammonium nitrate behave/decompose under heating if I want to boil down my sodium nitrate solution, or when I do a distillation of the nitric acid reaction mixture?

I am worried about ammonium nitrate exploding, or any ammonia formed neutralizing my nitric acid.

Or should I just use calcium ammonium nitrate directly (zhmapper video) and deal with the calcium sulphate?

Cheers.

[Edited on 28-10-2019 by artemov]
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[*] posted on 28-10-2019 at 02:57


i'm doing pretty much the same thing you want to do. i bought a 5kg bag of calcium nitrate (the only nitrate source they still sell here in garden centers), but once home i noticed it mentioned in the NPK description that it had some ammoniacal nitrogen, aka ammonium nitrate.
my process involves adding sodium hydroxide to a saturated solution of calcium nitrate/ammonium nitrate fertilizer (i'm using sodium hydroxide as i have 1kg of very old and carbonated hydroxide, not usable for many things anymore). ammonia did develope while adding the sodium hydroxide, but it was a small quantity, just a light smell. next, once the solution was neutral to slightly basic i decanted and then filtered it to remove the calcium hydroxide/carbonate, and then i boiled down the solution. there aren't any dangers in doing so as any ammonium nitrate reacted with the hydroxide or the carbonate to form ammonium hydroxide (that escapes during boiling) and ammonium carbonate (that easily decomposes to CO2 and NH3 during boiling).
i'm storing the sodium nitrate i made until the day i decide to go on to the production of nitric acid.

in your case by using sodium carbonate you get ammonium carbonate, that decomposes during boiling, so don't worry about ammonium nitrate exploding while heating to dryness, just be sure to add enough carbonate to react all the ammonium nitrate.





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TheMrbunGee
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[*] posted on 28-10-2019 at 06:07


I did a video on calcium nitrate=>sodium nitrate. Actually ended up converting it to nitric acid, but did not film that.

Here is the link

I did not convert my bicarbonate. An as I learned later on- my Ca nitrate eas also mixed nitrates, not pure stuff. Yield was 76% and that is with wrong stoichiometry. Ammounts in video are for pure calcium nitrate. Hope it helps some way.

[Edited on 28-10-2019 by TheMrbunGee]




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[*] posted on 28-10-2019 at 06:31


Quote: Originally posted by TheMrbunGee  
I did a video on calcium nitrate=>sodium nitrate. Actually ended up converting it to nitric acid, but did not film that.

Here is the link

I did not convert my bicarbonate. An as I learned later on- my Ca nitrate eas also mixed nitrates, not pure stuff. Yield was 76% and that is with wrong stoichiometry. Ammounts in video are for pure calcium nitrate. Hope it helps some way.

[Edited on 28-10-2019 by TheMrbunGee]


Thanks Ubya and TheMrbunGee.

Why are there so much gas evolved when the calcium nitrate solution are added to the resulting carbonate solution?

If ammonium nitrate is present, the resulting ammonium carbonate would decompose into NH3 and CO2, this would give lotsa ammonia, not just "some ammonia". If no ammonium nitrate is present, there won't be any gas evolve right?

[Edited on 28-10-2019 by artemov]

[Edited on 28-10-2019 by artemov]
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[*] posted on 28-10-2019 at 07:13


if you add the carbonate to a cold solution (or RT) of calcium/ammonium nitrate, the ammonium carbonate formed is unstable but not that much, so there will be formation of bubbles but not that much, when you boil the solution the evolution of gas will be buch more, so to destroy the ammonium carbonate you should boil the solution anyway




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artemov
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[*] posted on 28-10-2019 at 08:04


Thanks Ubya.
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[*] posted on 30-10-2019 at 00:46


Any form of ammonium can be destroyed by heating in solution with Na2CO3 or K2CO3. Yesterday I did a (NH4)2S2O8 to K2S2O8 reaction by gently heating the solution containing (NH4)2S2O8 and K2CO3 and trapping the evolving ammonia in a flask with water (I needed that ammonia, otherwise I would just do the reaction in cold solution, utilizing the lower solubility of K2S2O8).

The yield was less than satisfactory (I guess, some of the S2O82- anion decomposed on heating), but I've got a decent amount of K2S2O8 crystals.




Smells like ammonia....
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[*] posted on 30-10-2019 at 02:07


Quote: Originally posted by ave369  
Any form of ammonium can be destroyed by heating in solution with Na2CO3 or K2CO3. Yesterday I did a (NH4)2S2O8 to K2S2O8 reaction by gently heating the solution containing (NH4)2S2O8 and K2CO3 and trapping the evolving ammonia in a flask with water (I needed that ammonia, otherwise I would just do the reaction in cold solution, utilizing the lower solubility of K2S2O8).

The yield was less than satisfactory (I guess, some of the S2O82- anion decomposed on heating), but I've got a decent amount of K2S2O8 crystals.


I am also thinking about trapping the evolved ammonia to make some ammonia solution for future use. But wouldn't CO2 be also evolved thus making ammonia bicarbonate in the trap?
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[*] posted on 30-10-2019 at 12:29


CO2 is much less soluble than ammonia. Ammonia readily dissolves when the tube does not touch the water. CO2 needs bubbling to dissolve.



Smells like ammonia....
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[*] posted on 30-10-2019 at 12:48


The calcium sulfate isn't really that much of a problem. You'll need to distill twice to get azeotropic anyway, which negates the issue of ammonium nitrate in the acid on the first pass. The explosion risk is zero on the first pass because CAN has a very low proportion of ammonical nitrogen, consisting mostly of calcium nitrate (and later, calcium sulfate). On the second pass, there is zero risk of explosion unless you heat the flask to dryness (which is bad practice anyway), and in any case actually getting the tiny amount of residual AN to detonate would be very very unlikely even if you deliberately tried.

AN is very difficult to set off. The fertilizer industry used to use dynamite to free caked AN from silos regularly without issue until a series of devastating explosions were linked to the practice. The NOx and acid vapors are far more of a safety hazard in this case, since your energy inputs are nowhere near what dynamite could do.

I am zhmapper, BTW.
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[*] posted on 31-10-2019 at 02:46


Thanks milady, and hi zhmapper!

In your vid you have a solid chunk of calcium sulphate left, did you heat it to dryness, and how did you clean out the flask after? Cheers.
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[*] posted on 31-10-2019 at 03:26


i had the same thought but my local seller only sell 50 Kg bags.it's about 60$ and i don't need that much, plus ones i open the bag (actually it's two bags one inside of the other) i cant store it becouse its hygroscopic nature.it's much safe and cheap to buy 70% HNO3 .(1 Kg=1$)

[Edited on 31-10-2019 by rockyit98]




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[*] posted on 23-1-2021 at 11:05


Please explain me, because I'm just too stupid to figure it out. Is calcium ammonium nitrate a mixture of calcium and ammonium nitrate, or is it a separate complex that is formed under ?what? conditions, and does it break when it is dissolved (in water)?

Apparently it forms a double salt of 5Ca(NO3)2•NH4NO3•10H2O. What this does do if it's heated to evaporate water? Would the AN dissolve out of the Ca nitrate if washed with a solvent that does not dissolve it but does the AN?

The mixture also contains ammonium sulfate and ammonium phosphate. Doesn't these simply form nearly-insoluble calcium salts and crash out of a solution?

[Edited on 23-1-2021 by Fyndium]
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[*] posted on 23-1-2021 at 16:40


15.5-0-0 is pure calcium nitrate. Calcium ammonium nitrate is usually a mix of ammonium nitrate and insoluble calcium carbonate to deter explosive making, although can sometimes be other things as well.
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[*] posted on 23-1-2021 at 17:34


I think pure anhydrous Ca(NO3)2 would be 17%ish N. A complex of 5 Ca(NO3)2, 10 H20, NH4NO3 would be 15.56% N by mass. The Ca(NO3)2, 4H2O complex is 11.86%. A product labeled "calcium nitrate" can be any of the above. A product labeled calcium ammonium nitrate can be either the complex mentioned above, or simply ammonium nitrate with calcium carbonate mixed in.

Assuming you have the complex, is there any reason not to just add water and sulfuric acid and distill?

Another idea, for lower concentration nitric acid: add the right amount of water and calcium hydroxide to the complex to convert all the ammonium to ammonium hydroxide. Boil it to expel gaseous ammonia. Add the right amount of sulfuric acid, and separate the calcium sulfate that precipitates. I'm not sure how easy it is to completely remove ammonia and calcium sulfate from aqueous solution, the end product would probably have a few percent sulfate impurities. But depending on what the end product acid is needed for, it might be a quick and dirty way to get HNO3.

[Edited on 24-1-2021 by Vomaturge]




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[*] posted on 24-1-2021 at 06:19


Ah, I'm not aiming for HNO3. I have plethora of methods for that, and it is pretty much just mix sulfuric acid or sodium bisulfate with any - even quite impure - nitrate mixture and go.

I just want to study purification methods of all kinds of substances for fun. It suddenly provides very useful when a need arises and you know exactly how to get the stuff.
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[*] posted on 24-1-2021 at 07:19


When you dissolve 5Ca(NO3)2•NH4NO3•10H2O in water the salt will "break". The co-crystallization only exists when crystallized. When you dissolve the salt in water you won't see any difference between for example a solution of the double salt, separate hydrated calcium nitrate and ammonium nitrate or the anhydrous salts. In solution there are just calcium, ammonium and nitrate ions in water.

If you would heat the double salt it will dissolve in its crystalline water, again losing its double salt characteristics. I don't know what would happen if you would freeze dry it, I guess the water is needed for the crystal structure and the crystals will fall apart into a mixture of calcium and ammonium nitrate.

I can't think of a solvent that could dissolve one of the two salts without dissolving the other, this is probably the reason why they chose this combination of salts, to make it harder to separate. At least the ammonium nitrate with added calcium carbonate is quite easy, just dissolve, decant and boil down.

[Edited on 24-1-2021 by Tsjerk]
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[*] posted on 24-1-2021 at 07:29


Hence it's usually mixed with ammonium sulfate, which crashes out CaSO4. The mixture msds I checked contains sulfate and phosphate of ammonia, and apparently as it is purposed to be spread directly to soil, crashing out is not an issue, so dissolving and filtering should leave only ammonium nitrate, potassium chloride, and what remains of the rest, as it either reacts to depletion or some will remain unreacted.
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