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Problem with Potassium nitrate


Artu

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So i bought some kno3 fertilizer called yara krista k plus and when i tried it with sugar it didnt burn at all i thought the moisture could be a problem so i put it in the oven for 2 hours 60C and i tried it again and it didnt work then i milled my powdered sugar and kno3 and mixed it good and then it worked but when i tried it again the day after that it didnt work i saw the sugar melting but the kno3 doing nothing i am considering to recrystallize it What should i do?

sorry for my bad english.

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It would be helpful to know a little more about the composition you used.  How much sugar, how much KN03?  You said it worked after drying and milling together, but it didn't work the next day - how did you store it?  (maybe the comp absorbed moisture overnight). 

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Why not just test it preparing meal powder.

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39 minutes ago, cmjlab said:

It would be helpful to know a little more about the composition you used.  How much sugar, how much KN03?  You said it worked after drying and milling together, but it didn't work the next day - how did you store it?  (maybe the comp absorbed moisture overnight). 

So the fertilizer has an npk number 14-0-38 and i used 35% sugar and 65% kno3 i stored it in a plastic container without a lid.now i have a lid there but if the moisture is the problem im probably going to have to dry it again

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11 minutes ago, Zumber said:

Why not just test it preparing meal powder.

Im going to try that.

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2 hours ago, Artu said:

So i bought some kno3 fertilizer called yara krista k plus and when i tried it with sugar it didnt burn at all i thought the moisture could be a problem so i put it in the oven for 2 hours 60C and i tried it again and it didnt work then i milled my powdered sugar and kno3 and mixed it good and then it worked but when i tried it again the day after that it didnt work i saw the sugar melting but the kno3 doing nothing i am considering to recrystallize it What should i do?

sorry for my bad english.

Maybe you've already solved your problem, but I can help you here.
I in fact use the same source. It doesn't come in a very fine grain, it comes in pellets. This is because they add some sort of clay to make it easier to dissolve. I would HIGHLY recommend a recrystallization. I don't know the exact amount of kno3/clay ratio, but I'll assume it's somewhere around 20% clay, 80% KNO3, judging by my yields when recrystallizing. 
When I made rocket fuel, I had the same problem. Even if you grind it down into a fine powder, it will become rock hard the next day.

But even after recrystallization, store your KNO3 in a closed jar, preferably with as little free space as possible. Even after the recrystallization you will have to dry your kno3 every week or so.
Hope this helps!

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10 minutes ago, PillaDoubleG said:

Maybe you've already solved your problem, but I can help you here.
I in fact use the same source. It doesn't come in a very fine grain, it comes in pellets. This is because they add some sort of clay to make it easier to dissolve. I would HIGHLY recommend a recrystallization. I don't know the exact amount of kno3/clay ratio, but I'll assume it's somewhere around 20% clay, 80% KNO3, judging by my yields when recrystallizing. 
When I made rocket fuel, I had the same problem. Even if you grind it down into a fine powder, it will become rock hard the next day.

But even after recrystallization, store your KNO3 in a closed jar, preferably with as little free space as possible. Even after the recrystallization you will have to dry your kno3 every week or so.
Hope this helps!

Exactly what i was thinking i am going to recrystallize it and store it in a closed jar now and i am going to dry it

Thank You!

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51 minutes ago, Artu said:

Exactly what i was thinking i am going to recrystallize it and store it in a closed jar now and i am going to dry it

Thank You!

No problem, hope it works for you! Just one other thing. I would recommend milling down the KNO3 after recrystallization, so it's easier to dry it.
Stay safe ;)

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Definitely sounds like moisture content issue to me. Are you trying to light it with a match or a blowtorch? It should definitely still burn even with moisture. You may be failing to get it hot enough. Well enough mixed. Or it is really really wet. It could also be your sugar, is it a fine powder or a crystal? I’d recommend ensure it’s well mixed and lighting it with a blow torch not a lighter/ match.

It’s you’re using it for rockets, it’s absolutely critical it is dry or they will not fly. You can dry it much hotter than 60C, I dry mine at 120C for 15 minutes. Figured that one out in my first pyro experiment at 14… very disappointing otherwise ;) 

There’s no way it contains 20% clay. Many people use Krista K without issue. I have used it without issue. But the grade I have is 14-0-46, which is a bit purer. May be from a different mine site.

Pilla, your loss is due to KNO3 that remains solvated in the supernatant not clay. If it is clay, which some fertilisers do have, KCl being a major one, this is removed by filtration and presents as a gunk on the top of your liquor. 

Pure KNO3 has a NPK rating of 13.5-0-46.2. A rating of 14-0-38 indicates contamination with a nitrogen containing compound without potassium, but not enough to matter. It should still work totally fine. It could be sodium nitrate, magnesium nitrate, or any other mineral that occurs naturally along with KNO3 in the deposit. Nobody recrystallises it. 

AP. 

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4 hours ago, PillaDoubleG said:

But even after recrystallization, store your KNO3 in a closed jar, preferably with as little free space as possible. Even after the recrystallization you will have to dry your kno3 every week or so.
 

"Every week or so"? Not if he keeps it sealed up, preferably with a silica packet or two included. Oven drying's easy but a waste of time if you protect your dry KNO3 (and charcoal, and strontium nitrate...) from moisture in the first place.

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On 2/11/2024 at 6:13 PM, AustralianPyromaniac said:

There’s no way it contains 20% clay. Many people use Krista K without issue. I have used it without issue. But the grade I have is 14-0-46, which is a bit purer. May be from a different mine site.

Pilla, your loss is due to KNO3 that remains solvated in the supernatant not clay. If it is clay, which some fertilisers do have, KCl being a major one, this is removed by filtration and presents as a gunk on the top of your liquor. 

AP. 

Yeah tbh it really isn't, I just assumed that because I would always lose about that much per crystallization, but actually just not recovering as much as possible.
Still, it's still enough clay to make a decent difference.
 

21 hours ago, SharkWhisperer said:

"Every week or so"? Not if he keeps it sealed up, preferably with a silica packet or two included. Oven drying's easy but a waste of time if you protect your dry KNO3 (and charcoal, and strontium nitrate...) from moisture in the first place.

True as well, mentioned that since I usually do it that way, since my container leaves a lot of air in it... If you store it how you mentioned, there really is no reason to dry it as often as I do.

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  • 4 weeks later...

Sounds very strange. I have used krista k plus straight from the package. Milled of course, but it's very pure.

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I recently got a bag of the same yara Krista. The bag was ripped and it was sitting in a barn for since before I started my current job(8 years). I haven't used it for anything yet, but I did recrystallize some to check purity. And it looked pretty damn good. The filter was clean, crystals looked excellent. The remaining water was slightly discolored. But I think that's only because I didn't rinse my coffee pot when I heated the water before dissolving IMG_20240211_192239083.thumb.jpg.115e5557a4d26ea4eb2cc9c66b572cd7.jpg

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On 2/11/2024 at 3:23 PM, PillaDoubleG said:

 it comes in pellets. This is because they add some sort of clay to make it easier to dissolve. I would HIGHLY recommend a recrystallization. I don't know the exact amount of kno3/clay ratio, but I'll assume it's somewhere around 20% clay, 80% KNO3, judging by my yields when recrystallizing.

There is zero clay in YKK-plus, ffs. It's technical-grade KNO3.

"...around 20% clay..." Cheezus.

How tf would adding clay to KNO3 help it to dissolve??? smh

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17 hours ago, SharkWhisperer said:

There is zero clay in YKK-plus, ffs. It's technical-grade KNO3.

"...around 20% clay..." Cheezus.

How tf would adding clay to KNO3 help it to dissolve??? smh

Sorry, i was just guessing with the 20% margin, its way less than that.

But the clay dissolving part, i just said clay, but im not sure if its "clay", probably just some soluble material.
When i was buying urea,  they had a more expensive option that was actually lower purity urea, but it had more "clay" in it, to make it easier to dissolve.

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Clay doesn't make anything dissolve better.  Yara Krista K plus is pretty pure actually, probably 97+% if not closer to 99%.  If there's any clay in it, of which there would be minimal, it's often added as a coating on top of the prills to make them less prone to absorb water or make them harder.  Harder granules shatter less while spreading when used in agriculture.  That said, krista k plus is not a prilled form.

https://www.yara.co.uk/crop-nutrition/fertiliser/soluble/yaratera-krista-k-plus/

This is a grade of potassium nitrate that most seek out.  The material designed to be dissolved or fully soluble for greenhouse or hydroponics tends to be among the purest common grades available.  

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I have never in my life needed to recrystallize KNO3 for fireworking purposes. In the US at least, the tech grade/horticultural grade is sufficient purity for BP as-is.

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Just a quick suggestion if you do choose to recrystallize potassium nitrate.  Don't go too aggressive on the initial dissolving concentration.  If you really try to go fully saturated on the hot side of it, when you cool it to crystallize, it will probably set up into a brick.  The solubility curve really drops off at low temperatures.  You can get pretty good recovery even without pushing it to the limit.  It helps a lot when hot filtering too if you're not dealing with a nearly saturated solution.    

Also, those solubility curves are incomplete.  Particularly with sodium and potassium nitrate, they're so concentrated the true saturation temp/boiling point is closer to 110C for sodium nitrate, and 117C for potassium nitrate.  You can dissolve a ton of material in water.  

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There shouldn't be anything insoluble in this type of kno3... so filtering or crystallization will do nothing in my mind. The only real contaminate is the anti-caking agent which is pretty hard to get rid of. A common anti-caking agent for kno3 is "alkyl naphthalene sulphonate" at 0.5% or so...

Edited by ThunderEx
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