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Author: Subject: Lanthanide Woes
urenthesage
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[*] posted on 27-8-2016 at 14:49
Lanthanide Woes


I recently purchased some neodymium metal that Im certain was raw neodymium (IE it had a payload of praseodymium with it). I reacted a chunk (I forget the weight) with strong nitric acid and assumed I would eventually get pretty pink crystals of neodymium nitrate. What I got instead is a tarry purple brown goop. How did I f&^k this up? is it praseodymium gumming up the works? Is there a way to separate Nd nitrate from this gooey mess? Help. I need it. Thanks
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elementcollector1
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[*] posted on 27-8-2016 at 15:02


First: Where did you purchase it from?
Second: What is 'raw' neodymium? Are you thinking of mischmetal? Because any neodymium that's been purified to metal is usually made free of praseodymium and other metals, last I recall.




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blogfast25
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[*] posted on 27-8-2016 at 17:10


Quote: Originally posted by urenthesage  
I recently purchased some neodymium metal that Im certain was raw neodymium (IE it had a payload of praseodymium with it). I reacted a chunk (I forget the weight) with strong nitric acid and assumed I would eventually get pretty pink crystals of neodymium nitrate. What I got instead is a tarry purple brown goop. How did I f&^k this up? is it praseodymium gumming up the works? Is there a way to separate Nd nitrate from this gooey mess? Help. I need it. Thanks


Try precipitating the lanthanides as hydroxides with ammonia. Filter, wash filter cake and semi-calcine to get the oxides.

Black spots would point to Pr6O11, the mixed III,IV oxides of Pr. I've seen them in crude La2O3.

Needless to say, these elements are very hard to separate.




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diddi
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[*] posted on 28-8-2016 at 00:31


as elementcollector says Pr and Nd along with Ce are major components in mischmetal. if you have pure Nd it will have a pink oxide powdery layer, pure Pr has a green oxide powdery layer. they react with air and rapidly in acids




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blogfast25
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[*] posted on 28-8-2016 at 04:37


Quote: Originally posted by diddi  
as elementcollector says Pr and Nd along with Ce are major components in mischmetal.


Mischmetal's composition is well known. But OP doesn't appear to have bought Mischmetal, more like 'technical grade' Nd.




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urenthesage
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[*] posted on 28-8-2016 at 05:01


Quote: Originally posted by blogfast25  
Quote: Originally posted by diddi  
as elementcollector says Pr and Nd along with Ce are major components in mischmetal.


Mischmetal's composition is well known. But OP doesn't appear to have bought Mischmetal, more like 'technical grade' Nd.


I think youre right, I think it would be technical grade. I got it from china off of a guy I trust from past experience. Mabee his sample is a piece from the Nd that hasnt been purified yet, what I meant by raw.
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urenthesage
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[*] posted on 28-8-2016 at 05:26


A question pour vous, where would I go to find out the solubility of these chemicals in solvents? Mabee I can use a solvent to separate the neodymium salt from whatever the tarry goop is?
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diddi
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[*] posted on 29-8-2016 at 00:06


hard work I would expect. Nd oxalate is highly insoluble, and often used as a route to separating some of the lanthanides. there has been some interesting work done by SM members regarding Nd from magnets also.



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blogfast25
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[*] posted on 29-8-2016 at 07:08


Quote: Originally posted by urenthesage  
A question pour vous, where would I go to find out the solubility of these chemicals in solvents? Mabee I can use a solvent to separate the neodymium salt from whatever the tarry goop is?


Erm... any idea what the 'tarry goop' is? If organic in nature then shaking with a hydrocarbon might transfer it all into the organic phase.




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Brain&Force
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[*] posted on 30-8-2016 at 09:55


I'd take blogfast's advice and try to extract the stuff with toluene or some other nonpolar solvent. At the same time, I don't really see what organic impurities could exist from reacting the metal with nitric acid.

Then dissolve the crude nitrate in water and precipitate the hydroxide with ammonia. I highly recommend making the acetate instead if you want to grow crystals, as it's far less hygroscopic - just dissolve the hydroxide in acetic acid and crystallize it. If there's a higher praseodymium oxide present, it'll remain as a solid and can be filtered off.




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urenthesage
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[*] posted on 3-9-2016 at 11:52


Quote: Originally posted by Brain&Force  
I'd take blogfast's advice and try to extract the stuff with toluene or some other nonpolar solvent. At the same time, I don't really see what organic impurities could exist from reacting the metal with nitric acid.

Then dissolve the crude nitrate in water and precipitate the hydroxide with ammonia. I highly recommend making the acetate instead if you want to grow crystals, as it's far less hygroscopic - just dissolve the hydroxide in acetic acid and crystallize it. If there's a higher praseodymium oxide present, it'll remain as a solid and can be filtered off.




Thanks. I tryed the hydroxide and it came off looking uniform, far less of a mess than I had originally. Ill try acetic acid as soon as I can make some glacial stuff. You just taught me something valuable that I can use in the future, that being the OH precipitating from ammonia. Thanks again!
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[*] posted on 24-2-2018 at 13:15


urenthesage did you remove the coating off the magnet before dissolving in HNO3?
If not then you'll need excess ammonia to keep the Ni & Cu in soln.




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