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Author: Subject: Convert NaNO3 to KNO3 and purify it
hissingnoise
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[*] posted on 21-1-2019 at 03:37


Why do you think it contains NaNO3?

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PyroPlatinum
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[*] posted on 21-1-2019 at 07:29


Quote: Originally posted by hissingnoise  
Why do you think it contains NaNO3?



Because it says in the label explicitly that it has. And potassium nitrate too. But unfortunately they never say how much of each.. that make the calculations a little difficult...

[Edited on 21-1-2019 by PyroPlatinum]
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[*] posted on 22-1-2019 at 21:29


So. I have done the first recrystalization, and so far i've got about 57,5 grams of (a bit impure KNO3). That's about 12% of the total nitrate i dissolved in the water (471,2 grams).
Tried again to recrystallize but very little crystallized out. (with a bit of NaNO3 i think or it was only ice..)
Anyway. Now i think I'm gonna have to boil it down to about 75% the total volume of the solution and try to recrystallize more again.
If I'm doing something wrong please feel free to tell me.
And thanks for everyone that helped me out so far.

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PyroPlatinum
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[*] posted on 22-1-2019 at 21:41


And btw, i have found here where i live sacks of Potassium Nitrate im fertilizer form with about 90% purity. (I think).
They are selling it for about $55 for each 25 Kg sack.
But i also found out that it has some Magnesium Sulfate (MgSO₄) as the impurity in it.
So i'm thinking how i would get rid of that sulfate if i buy the nitrate in the future...
I think i would have to convert that magnesium sulfate into chloride before trying to crystallize out the potassium nitrate, because i'm afraid that the sulfate might crystallize out with the nitrate, due to it's relatively low solubility at low temperatures (the double of KNO3 though).
And that's the only option before magnesium iodide, bromide, acetate and chlorate. And i would not want to waste my chlorate with this! lol
Any suggestions?

[Edited on 23-1-2019 by PyroPlatinum]
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MrHomeScientist
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[*] posted on 23-1-2019 at 13:56


Now that you've made it through the spam, here's an idea: You could approach it from the other direction. Rather than cooling and crystallizing the KNO3 at low temperature, you could try recovering the MgSO4 from a hot solution instead. The solubilities are much farther apart at high temperature. So, dissolve the maximum amount of nitrate possible at near-boiling temperature, then filter off any remaining solids. That will be a lot of your sulfate contamination.

Or, perhaps even better: react a solution of your fertilizer with calcium nitrate. That will precipitate out ALL the sulfate, leaving you with the much more soluble magnesium nitrate to work with. Then you're back to the original procedure of cooling and recovering the KNO3.
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PyroPlatinum
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[*] posted on 23-1-2019 at 14:50


Quote: Originally posted by MrHomeScientist  
Now that you've made it through the spam, here's an idea: You could approach it from the other direction. Rather than cooling and crystallizing the KNO3 at low temperature, you could try recovering the MgSO4 from a hot solution instead. The solubilities are much farther apart at high temperature. So, dissolve the maximum amount of nitrate possible at near-boiling temperature, then filter off any remaining solids. That will be a lot of your sulfate contamination.

Or, perhaps even better: react a solution of your fertilizer with calcium nitrate. That will precipitate out ALL the sulfate, leaving you with the much more soluble magnesium nitrate to work with. Then you're back to the original procedure of cooling and recovering the KNO3.


lol these spams pisses me of so much.

Hmmmm that sounds pretty straightforward... gonna try that once i buy of that nitrate sacks. I think that heating a concentrated solution of it and filter off the sulfate would be much simpler.

Oh and about the Calcium nitrate method... it really makes sense but it would require this additional salt. But couldn't i use Calcium Chloride?
Would end up with Calcium Sulfate that i would filter off, and after that i might just recrystallize the Potassium nitrate and leave the Magnesium Chloride in solution.
And Calcium Chloride is pretty cheap compared to it's nitrate counterpart.
(But i understand that would yield less nitrate)
Anyways. Good suggestions. Thanks.
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28-1-2019 at 10:13
MrHomeScientist
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[*] posted on 28-1-2019 at 14:14


Sure, chloride would work. It's the calcium ion that does the heavy lifting here. I just chose nitrate to minimize the number of extra ions.
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