Sciencemadness Discussion Board

production of nitric acid using a fertilizer

CHEMxpl - 14-11-2016 at 13:06

Hello guys
here in my country i can get an npk 15 15 15 fertilizer for about 1USD for 2.5lbs witch containes 42%ammonium nitrate ,phosphoric acid and a potassium salt
i took 11pounds and disolved everything in water and filtered then added some calcium hydroxide and left it for a few days to fully react ( a strong ammonia odor is coming off of it )
and i plan on filtering again and adding about a gallong of 30% sulfuric acid and filter the calcium sulfate percipitate and distill it over to get nitric acid
is it possible ?and is there any better ways to do it ?
thanks

aga - 14-11-2016 at 13:26

Get the nirate out first, dry, then distill that with sulphuric acid.

Edit:

Welcome to ScienceManess !

[Edited on 14-11-2016 by aga]

Jstuyfzand - 14-11-2016 at 13:31

What is this amazing country you speak of?

CHEMxpl - 15-11-2016 at 04:27

I live in Algeria ;
okay so i've tried samples (100grams) and dissolved everything and recrystallized it but since the solubility of AN is very high even in cold water i got some potassium nitrate cristals and some maybe phosphate impurities crash out as well
now i don't know if there's potassium chloride that reacts with the AN (hope not cuz that would prodce hcl and make aqua regia)
if i try to get the nitrates out alone i'll lose a lot, 50+%.

Tsjerk - 15-11-2016 at 07:46

Why don't you add sulfuric acid to the solution you got after the first filtration (before adding calcium hydroxide) and distill this? You will have a bit more salts in your pot, but nothing that is interfering with your distillation.

What concentration are you aiming for?

CHEMxpl - 15-11-2016 at 13:00

I'm trying to get the azeotropic concentration of 68% even if i had to run multiple distilations
but that sounds a great idea
i guess i'll get anothger 11lbs and do that but what concernes me is the possiblity of the presence of chlorides
how do i know if there's any? and how am i gonna get rid of them?
and also does phosphoric acid reacts with calcium hydroxide?

Maroboduus - 15-11-2016 at 13:10

Chlorides in nitric acid cause a precipitate with silver.

Tsjerk - 15-11-2016 at 23:21

Phosphoric acid obviously reacts with hydroxides, but both phosphoric acid and its salts don't come over in this distillation.

Fertilizers are usually poor in chlorides as plants don't accumulate chloride too well, after repeated use the fertilizer would then make the soil salty because chloride gets enriched.

@ Maroboduus, as does silver with phosphate and sulfate, especially in concentrated solutions. So not practical here.

[Edited on 16-11-2016 by Tsjerk]

CHEMxpl - 16-11-2016 at 08:20

@Tsjerk
okay that's amazingly helpful thanks
also it says that it containes 7.5% nitric nitrogene and 7.5%ammoniacal nitrogene
according to my calculation there's 33% of no3- (42%ammonium nitrate),is it correct?
and i have 5kgs of it so 330x5=1650grams of no3-
let's just say i would loose 150grams of it so we're left with 1500g
can some one tell me how much 68%nitric acid can i get ?

Maroboduus - 16-11-2016 at 08:40

Quote: Originally posted by Tsjerk  
Phosphoric acid obviously reacts with hydroxides, but both phosphoric acid and its salts don't come over in this distillation.

Fertilizers are usually poor in chlorides as plants don't accumulate chloride too well, after repeated use the fertilizer would then make the soil salty because chloride gets enriched.

@ Maroboduus, as does silver with phosphate and sulfate, especially in concentrated solutions. So not practical here.

[Edited on 16-11-2016 by Tsjerk]


Maybe you could explain how sulphate and phosphate get into the distillate?
I said in nitric acid, not in a broth of mixed fertilizers.
This is an old method for testing nitric acid for chlorides.

Tsjerk - 16-11-2016 at 08:53

CHEMxpl was talking about not wanting to form aqua regia, which would happen when sulfuric acid is added to the fertilizer solution (so before distillation).
Ofcourse you could probably show this process after distillation as HCl together with a couple of other N/O/Cl species comes over, but that would be to late in this case as you already distilled. Once aqua regia has formed there is no way to get rid of it anymore, Woelen has a nice post about it somewhere.

68% nitric acid is 68% weight /weight, with a density of about 1,4 kg/liter. So 0.68 x 1.4 kg nitric acid will give you one liter 68% nitric acid.

[Edited on 16-11-2016 by Tsjerk]

CHEMxpl - 16-11-2016 at 09:39

thank you guys you helped me a lot !

CHEMxpl - 18-11-2016 at 23:59

update: adding the calcium hydroxdie actually helps a lot as i noticed i'm getting much purer and cleaner nitrate cristals
and it removed a alot of the phosphates
no all ihave to do is to add sulfuric acid and distil it

Tsjerk - 19-11-2016 at 00:27

I understand it helps with crystallisation of pure nitrate, but what I meant with adding sulfuric acid before calcium hydroxide was that you skipp the whole crystallisation part and distill directly. Don't let aga foul you in thinking you need pure nitrate salt for this.

So the whole procedure would be: dissolve fertilizer, filter, add sulfuric acid, distil off nitric acid.

CHEMxpl - 19-11-2016 at 04:34

yes of course that's what i'm doing
i just wanted to try it and see what it does
but next time i'll skip the calcium

anyway i'm very happy with this whole thnig
i can get nitric acid much much cheaper like this


[Edited on 19-11-2016 by CHEMxpl]