Extract potassium nitrate from npk fertilizer

[vegapunk]

Hello i have NPK fertilizer 20-20-20 and i want to extract potassium nitrate crystal from it is that possible and if so how can I do it??

 

[Vanadium 50]

Why? Why not just buy some potassium nitrate? What's the application here?

 

[DrJohn]

Perhaps the OP intends to add some sulfur and charcoal...
Buying some compounds on a particular list is monitored, remember.

 

[Borek]

Just because the fertilizer contains N and K doesn't necessarily mean it contains potassium nitrate.

Technically yes, it is doable. Practically it is much easier to buy the potassium nitrate itself.