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Author: Subject: The trouble with neodymium...
blogfast25
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[*] posted on 27-5-2015 at 17:46


Quote: Originally posted by DalisAndy  


Dude, oxalates decompose easily. Go look it up, like I did today. or you could use Lithium in ethanol (or what ever non-polar solvent you have). or when in doubt electrolysis, of it's sulphate form.


Why, what did you find, huh? Lithium in ethanol??? That's lithium ethoxide. How is that supposed to decompose oxalates?

Oxalates in acid conditions are oxidised to CO<sub>2</sub> by KMnO<sub>4</sub> but RE oxalates are extremely insoluble, making that process very slow, I would think...

The sandy pink form of Nd sulphate would only crystallise into the other, ruby form, so that solves nothing. Direct experience, BTW. The two forms have been encountered by several experimenters, myself included, on this forum.

[Edited on 28-5-2015 by blogfast25]




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[*] posted on 27-5-2015 at 17:56


Quote: Originally posted by blogfast25  
Quote: Originally posted by DalisAndy  


Dude, oxalates decompose easily. Go look it up, like I did today. or you could use Lithium in ethanol (or what ever non-polar solvent you have). or when in doubt electrolysis, of it's sulphate form.


Why, what did you find, huh? Lithium in ethanol??? That's lithium ethoxide. How is that supposed to decompose oxalates?

Oxalates in acid conditions are oxidised to CO<sub>2</sub> by KMnO<sub>4</sub> but RE oxalates are extremely insoluble, making that process very slow, I would think...

The sandy pink form of Nd sulphate would only crystallise into the other, ruby form, so that solves nothing. Direct experience, BTW. The two forms have been encountered by several experimenters, myself included, on this forum.

[Edited on 28-5-2015 by blogfast25]


First, they were to separate ideas. Second, couldn't you ignite it with Carbon, since it's similar in chemistry to magnesium. Which it's known to react with Carbon in sulphate form




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[*] posted on 27-5-2015 at 18:00


You don't need to: you need to pyrolyse the Nd oxalate in the presence of plenty of air oxygen. Probably 700 C or higher. That affords the oxide Nb<sub>2</sub>O<sub>3</sub>.

Treat that as I suggested to convert to sulphate. Eliminate any sodium as explained in the thread, if needed.




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[*] posted on 27-5-2015 at 21:27


Quote: Originally posted by DalisAndy  
I don't get why we haven't created a location to consolidate knowledge for projects? I mean like log all experiments done, so others can test it
Well, we do have a prepublications forum (that is somewhat underused.) we do try to encourage posting in existing threads rather than starting new ones -- so all the information is together in one place. And I think that some of the larger more significant threads have been summarised, but that is a large job for someone. It also puts a metaphorical lid on the thread.
What often happens however is that thread contributors are engaged in similar but slightly different experiments that benefit from discussion but the thread does not lend itself to a single tidy description of a procedure.
Besides, half the fun is in reading and encountering ideas and solutions that you had not considered before. That is where the learning happens. So what if you have to read a bit.
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[*] posted on 28-5-2015 at 05:44


There's also a lot of stuff in the open literature. The double sulphates method of separation I got from there. It's should not be hard to find it again via the Googly Interwebs.

That method is used for the industrial recovery of Nd from Nd magnets, acc. one paper.

[Edited on 28-5-2015 by blogfast25]




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[*] posted on 29-5-2015 at 09:07


When using the oxalic acid on the magnets. Which oxidation state is iron move to? Also there is a +2 iron oxalate



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[*] posted on 29-5-2015 at 09:21


Quote: Originally posted by DalisAndy  
When using the oxalic acid on the magnets. Which oxidation state is iron move to? Also there is a +2 iron oxalate


Non-oxidising acids oxidise iron to Fe(II).

Oxidising acids like HNO3 oxidise it to Fe(III).




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[*] posted on 29-5-2015 at 11:09


I think I fix/finished the oxalic acid method.

1. Treat with sulfuric acid to remove boron
2. Treat with oxalic acid, filter out neodymium oxalate
3. Treat neodymium oxalate with a base
4. Decompose hydroxide




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[*] posted on 29-5-2015 at 11:19


Quote: Originally posted by DalisAndy  
I think I fix/finished the oxalic acid method.

1. Treat with sulfuric acid to remove boron
2. Treat with oxalic acid, filter out neodymium oxalate
3. Treat neodymium oxalate with a base
4. Decompose hydroxide


Fe(II) oxalate is very poorly soluble.

Nd oxalate is more insoluble than Nd hydroxide. Converting the Nd oxalate with base to Nd hydroxide therefore cannot work.

What do you mean by 'decompose hydroxide'?

[Edited on 29-5-2015 by blogfast25]




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[*] posted on 29-5-2015 at 11:23


The base treatment is to allow isolation of an oxide, thus a pure sample. If Fe(II) is not soluabe. Heat the Nd-Fe sulfate solution untill the Fe sulfate decomposes.



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[*] posted on 29-5-2015 at 11:34


Quote: Originally posted by DalisAndy  
The base treatment is to allow isolation of an oxide, thus a pure sample. If Fe(II) is not soluabe. Heat the Nd-Fe sulfate solution untill the Fe sulfate decomposes.


You really haven't got the foggiest, have you?

READ THE THREAD.




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[*] posted on 29-5-2015 at 12:16


What ?

Reading ?! Eeek !

Nobody ever said anything about having to read things before i signed up.

I want my money back !




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[*] posted on 29-5-2015 at 12:47


Quote: Originally posted by aga  

I want my money back !


Done. You want a tax deductible receipt for that refund?




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[*] posted on 2-6-2015 at 09:34


At what temperature does neodymium sulfatd decompose? Just curious, couldn't find it online. Also could someone explain the double salt method more? Mg has a high affinity for Nd. I read in one paper that you could melt down Mg and the magnets, and separate the Mg and Nd along with a Fe-B sludge. But that would require a blast furnace or a klim.



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[*] posted on 2-6-2015 at 09:54


Nd sulphate requires seriously high temperatures to fully decompose (to oxide). At a guess, several hours at near 1,000 C.

The double salt method works as follows.

The magnets are dissolved in an excess of 33 % HCl and filtered after dissolution and cooling.

Nd is now present as NdCl3, Fe as FeCl2, in a dark but transparent solution (no solids).

To the filtrate, somewhat diluted, is added powdered K2SO4. The amount is calculated so that the solution ends up saturated in K2SO4. The slurry is heated and simmered for about 1/2 hour. A sandy precipitate of Nd2(SO4)3.K2SO4.2H2O (could be .3H2O, can't remember right now) forms. The slurry is cooled and chilled (to maximise the insolubility of the double salt) and filtered off.

The filter cake is washed with cold, acidified saturated K2SO4 solution several times to remove any remaining iron(II). It's important to use an acidic wash to avoid oxidation of the Fe(II) to Fe(III) (which can precipitate as Fe(OH)3).

The washed filter cake doesn't have to be dried. It is treated with warm, strong ammonia which sets the K2SO4 free and converts the Nd to Nd(OH)3.

Filtering and washing extensively of the filter cake then affords relatively pure (RE > 99 % or better) Nd(OH)3, a starting point for Nd chemistry in general.


[Edited on 2-6-2015 by blogfast25]




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[*] posted on 2-6-2015 at 10:10


Ok thanks. I'm think I'm going to to cryastalize off neodymium sulfate after decomposing off the iron sulfate. Before it goes Fe(III)



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[*] posted on 2-6-2015 at 10:15


Quote: Originally posted by DalisAndy  
Ok thanks. I'm think I'm going to to cryastalize off neodymium sulfate after decomposing off the iron sulfate. Before it goes Fe(III)


It WON'T work.

Decomposing the iron sulphate will lead to partial hydrolysis of the Nd sulphate. Crystallising Nd sulphate is in itself not so easy: it's a poorly soluble compound with (quite exceptionally) higher solubility in the cold than hot.

[Edited on 2-6-2015 by blogfast25]




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[*] posted on 2-6-2015 at 14:21


Just calcined the oxalate to a gray oxide, then placed this in a mix of sulfuric acid and water. Left this overnight, and checked again this morning to find a sandy pink powder with traces of gray still mixed in, and a completely clear solution. Would this be pure, dilute neodymium sulfate? There's no way the oxalate could have survived in such quantity - it melted during calcination...



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[*] posted on 3-6-2015 at 05:09


Quote: Originally posted by elementcollector1  
Just calcined the oxalate to a gray oxide, then placed this in a mix of sulfuric acid and water. Left this overnight, and checked again this morning to find a sandy pink powder with traces of gray still mixed in, and a completely clear solution. Would this be pure, dilute neodymium sulfate? There's no way the oxalate could have survived in such quantity - it melted during calcination...


The only way to find out is to try and dissolve it in iced water in which it slowly dissolves.




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[*] posted on 3-6-2015 at 20:34


Would using a modified Alkaline extraction method work? Sulphates -> hydroxides?



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[*] posted on 3-6-2015 at 20:50


Oh gentleman I found a way to extract rare earth elements with sulfric acid, using a solvent extraction method.
http://etheses.whiterose.ac.uk/638/1/uk_bl_ethos_432307.pdf




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[*] posted on 4-6-2015 at 06:08


Quote: Originally posted by DalisAndy  
Would using a modified Alkaline extraction method work? Sulphates -> hydroxides?


REEs don’t respond to alkalis, they’re not amphoteric.

Quote: Originally posted by DalisAndy  
Oh gentleman I found a way to extract rare earth elements with sulfric acid, using a solvent extraction method.
http://etheses.whiterose.ac.uk/638/1/uk_bl_ethos_432307.pdf


Solvent extraction of lanthanides/actinides is nothing new. We (amateurs) tend to avoid it because of the required chemicals.




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[*] posted on 4-6-2015 at 12:17


Quote: Originally posted by blogfast25  

The only way to find out is to try and dissolve it in iced water in which it slowly dissolves.


Is it soluble in cold, diluted sulfuric acid? I tried putting the original mix in the freezer, just to see what happened - nothing did.




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[*] posted on 4-6-2015 at 12:33


Quote: Originally posted by elementcollector1  


Is it soluble in cold, diluted sulfuric acid? I tried putting the original mix in the freezer, just to see what happened - nothing did.


And for your next experiment you will put some sugar at the bottom of a glass of cold water and observe.

x days later: your sugar is still at the bottom of your glass. Conclusion: sugar is insoluble in cold water (W-R-O-N-G ! ! !)

At 0 C (or near) the rate of dissolution of Nd sulphate (or sugar) is very low. And without prolonged and intensive stirring it will NOT dissolve. Same as your sugar. And relying solely on diffusive dissolution is very, very slow.

Dilute H2SO4 won't have much effect but remember the Common Ion effect.

[Edited on 4-6-2015 by blogfast25]




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[*] posted on 8-6-2015 at 09:43


Quote: Originally posted by j_sum1  
...
4. Copy mrhomescientist's beautiful and highly effective apparatus
...

I'll grant it looks neat, but 'highly effective' is still yet to be seen! I just got back from a week-long vacation so I haven't thought about this in a while. (I hadn't done much of anything with it before that week either, but still...)

The current plan of attack is to do a dry run just heating a crucible of lithium metal under argon, to see if I can at least melt it without it catching fire. That will tell me if my inert blanket is sufficient. Then hopefully the heat won't have welded the pipe caps onto the body, and I can actually open the thing up after it cools. Then, if those checks pass, we'll move on to the main event.

If that works (fingers crossed!) I will post a nicely formatted article with photos and video going over the entire process in the Prepublication section (among other places).


Oh and Andy, I found that magnesium melt method a while back and posted it in the thread some pages ago. It's very interesting, but again you'd need an inert atmosphere, high temperature, sealed crucible setup which is very difficult for the amateur to achieve. It involves distilling Mg metal, so that'll give you some idea of the temperatures involved. I feel like this will be ignored again, but let me repeat once more: Read the thread. People have been remarkably patient in repeating themselves here so far.

[Edited on 6-8-2015 by MrHomeScientist]
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