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Author: Subject: The trouble with neodymium...
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[*] posted on 2-4-2012 at 12:08


Have you added oxalic acid yet?



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[*] posted on 2-4-2012 at 13:22


Nope. I'm waiting for the iron hydroxide to precipitate out (or should I just proceed even if it hasn't?)



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[*] posted on 3-4-2012 at 06:15


Yes, you can add oxalic acid at this point.

What should happen is that the solution goes green (slightly fluorescent too - this is the trisoxalato ferric complex) and a precipitate of neodymium oxalate will form. Allow the neodymium oxalate to settle, then filter off the supernatant liquid. Wash the filter cake with ample water, this is your relatively pure neodymium oxalate. It should look distinctly different under tungsten light and TL light.

CAUTION: oxalate bearing liquors are toxic. Good gloves and goggles are in order. Work calmly and know what you're doing. Be prepared to clean up any spills quickly and completely!

The reasons why no Fe(OH)3 precipitated can be:

* pH was too low
* iron concentration was too low
* both

But this should not impede anything.

[Edited on 3-4-2012 by blogfast25]




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[*] posted on 3-4-2012 at 17:09


Still with heat, right?



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[*] posted on 4-4-2012 at 04:26


No. The heat would have been needed to help dissolve the precipitate of Fe(OH)3. Now, RT is fine.



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[*] posted on 6-4-2012 at 18:41


Alright, I now have a relatively small amount of white precipitate (which probably contains leftover oxalic acid) and a pale-ish green solution. How do I test this for neodymium content? (HCl? Calcination?)



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[*] posted on 7-4-2012 at 05:18


Filter off and wash the Nd oxalate copiously with clean warm water to remove traces of oxalic acid and other solutes. Dry it, it should now look distinctly different in TL light and incandescent light.

Calcining the oxalate in air gives Nd2O3 which is reportedly soluble in strong (hot?) HCl, to give NdCl3 which can be crystallised (albeit with difficulty because it's very soluble and hygroscopic).




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[*] posted on 2-5-2012 at 04:44



I also finally managed to obtain the magnet from an old hard drive, but instead of only getting neodymium out, I'd also like to obtain the nickel. I found out that the brackets for the magnet are made of permalloy (80% Ni, 20% Fe), so that's quite some nickel. But after reading these posts I have doubts about that, because I got the impression that the casing itself is mostly iron, which is just electroplated with nickel... Does anyone know if the nickel content is really high enough and would be worth extracting? The wikipedia also has some info on permalloy and I think it would be possible...
Thanks for help :)



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[*] posted on 2-5-2012 at 05:07


Quote: Originally posted by Nathaniel  

I also finally managed to obtain the magnet from an old hard drive, but instead of only getting neodymium out, I'd also like to obtain the nickel. I found out that the brackets for the magnet are made of permalloy (80% Ni, 20% Fe), so that's quite some nickel. But after reading these posts I have doubts about that, because I got the impression that the casing itself is mostly iron, which is just electroplated with nickel... Does anyone know if the nickel content is really high enough and would be worth extracting? The wikipedia also has some info on permalloy and I think it would be possible...
Thanks for help :)



That’s quite interesting, Nathaniel, do you have some references for that claim? Personally I’m doubtful about it.

Of course it’s relatively easy to find out yourself. Dissolve the suspected Permalloy in nitric acid (nickel dissolves only with great difficulty in HCl or sulphuric acid, it resembles copper in that respect) and precipitate the metals as hydroxides with strong ammonia. Excess ammonia causes the nickel to re-enter solution as the nickel hexammonium complex (blue), so consider it a colour test, because smaller amounts of nickel would go unnoticed.

I’ve a load of these magnets, still in their brackets, so I might have a go myself…




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[*] posted on 2-5-2012 at 06:35


Thanks for reply, I had the same plan for separation in mind as the one you suggested :) I'll dissolve small amount of the casing in HCl/H2O2 (that should dissolve it). I can also test for the nickel with homemade DMG just to be sure :)
You can try yourself, but I'll deffinately do it on friday and post the results

http://www.scrapmetaljunkie.com/269/how-to-scrap-hard-drives...

http://en.wikipedia.org/wiki/Permalloy

The data in the first link seems very probable, because it says the alloy doesn't "let through" much magnetic field, which could damage other parts of computer so it's very useful for these purposes.


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[*] posted on 2-5-2012 at 08:23


Quote: Originally posted by Nathaniel  
Thanks for reply, I had the same plan for separation in mind as the one you suggested :) I'll dissolve small amount of the casing in HCl/H2O2 (that should dissolve it). I can also test for the nickel with homemade DMG just to be sure :)
You can try yourself, but I'll deffinately do it on friday and post the results




Oh, but I'll gladly wait for your results first. :D

HCl/H2O2 will probably do it but you'll need topping up with H2O2, as much of it tends to decay away w/o doing much. You could also try HCl/Na(or K)NO3 ("poor man's Aqua Regia")


[Edited on 2-5-2012 by blogfast25]




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[*] posted on 4-5-2012 at 02:00


Ok, so I did a few reactions and here are the results:

First I cut a piece of the suspected permalloy with a saw, with a piece of paper below to trap the filings.
I actually wanted to dissolve the piece that I cut, but the amount of filings was surprisingly large (looked large :P) so I decided to test those instead. The scale however did not show anything (so it was below 0,1g)

I put the filings in a 50ml erlenm.flask and added 3,5ml 30% HCl. I waited for the bubbling to cease and then heated the solution to dissolve everything and added 3ml water. The solution was strongly yellow. I added about 0,5ml H2O2 (30%) - the solution turned dark orange (Fe2+ --> Fe3+) I boiled a solution for a bit to destroy excess peroxide

Then I did the ammonia test: To 1ml of the solution I added 25% ammonia dropwise. Fe(OH)3 started forming after about 3 drops; I added 3,5ml total. After the percipitate settled, the solution above was clear and just a bit yellowish in colour.

Being quite dissapointed I took a few drops of this yellow solution and added some very diluted dimethylglyoxime solution. The colour didn't appear immediately, but after some shaking, the distinctive pink colour appeared.

So what should I assume from that? Everything being so diluted I don't know if (compared to iron) there's just a small amount of Ni present (and the DMG test just managed to detect it) or is the complex just too diluted for the solution to be blue? It would probably be best to dissolve the big piece too and make a more conc. sample, but I'd like to know if it's even worth the effort....

Thanks for helping out :)



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[*] posted on 4-5-2012 at 03:38


I think it's worth the effort for corroboration purposes. But I think the Ni you detected is coating, not alloy.

[Edited on 4-5-2012 by blogfast25]


Update:

My own quick test didn’t show up any Ni either. I dissolved a piece (about 0.1 g) of hard drive neomagnet bracket in a few ml of 70 % HNO3. In the mean time I prepared a solution of NiCl2.6H2O (0.4 g) in a few ml of DIW, as a control. I have no DMG so had to rely on (relatively weak) ammonia solution.

To the control was added 1 M NaOH till precipitation (Ni(OH)2 hydrate) occurred, then NH3 solution was added. The precipitate dissolved and a pale blue-lavender Ni ammonia complex solution was obtained. It’s much less intensely blue than its copper homologue.

After cooling (it is then pale yellow - not a hint of green) to the sample solution 1 M NaOH was added dropwise till a permanent Fe(OH)3 hydrate precipitation resulted. To this ammonia solution was added but the supernatant solution remained colourless. By now all ferric hydroxide has collected south and no blue colouration of the clear liquid is seen. This is not the behaviour of a 70 % Ni alloy, even though the NH3 test isn’t near as sensitive as DMG. Unless any nickel irreversibly co-precipitated with the ferric hydroxide, it strongly suggest the sample contains no or very little nickel.

Well known object lesson to all: don’t believe everything you read on the Tinkerwebs. ;)


[Edited on 4-5-2012 by blogfast25]




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[*] posted on 6-5-2012 at 22:43


I dissolved a 2g piece in HCl/HNO3 and the filtrate, after adding ammonia, was colourless. Test with DMG positive (strong pink), but no blue or green so I guess it really isn't a nickel alloy...
I thought the info on the web was ok, but I guess I was wrong...I was really happy to finally get some nickel, but I guess I'll have to look for an anode.. Thanks for help again :)



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[*] posted on 7-5-2012 at 05:26


Quote: Originally posted by Nathaniel  

I thought the info on the web was ok, but I guess I was wrong...I was really happy to finally get some nickel, but I guess I'll have to look for an anode.. Thanks for help again :)


Get some scrap Nichrome wire (hair driers etc): 80 % Ni/20 % Cr. Try separation based on Cr's amphoterism.




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[*] posted on 7-7-2012 at 07:45
Neodymium sulphate: another ‘funny turn’…


I got 165 g of neomagnets from a scrap merchant in return for some scrap metal and decided to try and turn it into neodymium sulphate once again. This time I chose to try and precipitate the sulphate by direct addition of 50 % sulphuric acid to a solution of ‘neomagnet chloride’.

So the magnets were crushed and reacted with about 500 ml of 36 % HCl, filtered to clarity and then to the filtrate a calculated amount of sulphuric acid was added. At first nothing happened but upon heating to about 90 C the sulphate dropped out as flaky crystals. And then I made a mistake. After decanting off the supernatant liquid I added cold water for rinsing and low and behold a good dollop of it dissolved immediately! Nd2(SO4)3 is of course much more soluble in cold than hot water but it’s only supposed to dissolve slowly in cold water. In short, I lost about 75 % of the crop to the wash water and filtrates. But that’s not the end of it…

The total volume had by then swollen to a hefty 1.2 L and I tried to precipitate the Nd as Nd2(SO4)3.K2SO4.3H2O, a very sparsely soluble double salt (discussed above), by taking advantage of the acid reserve of the solution. A calculated amount of 50 % KOH was added but nothing happened. Frustrated I decided to precipitate the lot, Fe included, with NaOH 50 % and start again. But low and behold, on slowly adding NaOH an off white sandy precipitate started dropping out. Adding the NaOH slowly while checking pH was low enough, I precipitated all the Nd, while keeping Fe3+ in solution, presumably as Nd2(SO4)3.Na2SO4.3H2O (the ammonium double salt is also known, all three are poorly soluble in water).

Filtered and washed with 0.1 M NaHSO4 (to prevent any Fe3+ from precipitating), the double salt was then treated with NaOH to convert it to Nd(OH)3 and Na2SO4. The Nd(OH)3 was then converted to Nd2(SO4)3, which tomorrow will be washed with small amounts of boiling 0.1 M H2SO4 and finally with boiling water.



[Edited on 8-7-2012 by blogfast25]




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[*] posted on 7-7-2012 at 15:05


I would not recommend the proposal of existence of the double salt you mentioned. As myself I tried putting some ammonium sulphate within the freshly purified Nd sulfate and when it just precipitated by evaporation it seemed not double salts formed as the Nd sulfate yield was just about the predicted within the calculations.



All of the (NH4)2SO4 was recovered from the supernatant solution later.
I dont believe you are right about the ammoniacal double salt, but

Can you please support that with stoichometric weighing?

I wan't to put that claim into my own post on double salt possibilities :D

Thanks!!

[Edited on 7-7-2012 by Poppy]




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[*] posted on 8-7-2012 at 04:30


Quote: Originally posted by Poppy  
I would not recommend the proposal of existence of the double salt you mentioned. As myself I tried putting some ammonium sulphate within the freshly purified Nd sulfate and when it just precipitated by evaporation it seemed not double salts formed as the Nd sulfate yield was just about the predicted within the calculations.
[Edited on 7-7-2012 by Poppy]


I got the information from a book but it did not state solubility of the salt. There also exists apparently a poorly soluble Cs2SO4.Nd2(SO4)3.3H2O.

Any next batch of Nd salts will be precipitated as K2SO4.Nd2(SO4)3.3H2O (the more insoluble one, apparently), because the single sulphate itself is too capricious for my liking. Then convert to Nd2O3.

Yesterday I had another mishap with a small left over (estimated less than 5 g worth of Nd). I converted it to Nd(OH)3, washed carefully, then dissolved in HCl 36 % (visual estimate of amount needed). I heated that and added what I felt sure was the right amount of H2SO4 50 % and… NOTHING happened. No precipitate at all. Not on cooling either.

Nd prices keep coming down. Reported FOB ex China about $150/kg for metal now.




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[*] posted on 8-7-2012 at 07:56


Yea I got an article discussing how Nd prices changed over time. To you think China will ever ship such an ammount of a single kilo of the product?
$150 is really cheap, such a good deal. Stock it and wait for inflation. Voila, you gain nothing, lol, but gets big money

Look at this:
"In general, alums are easier formed when the alkali metal atom is larger. This rule was first stated by Locke in 1902:[7] The failure of the sulphate of a given trivalent metal to unite with caesium sulphate to a compound of the type CsMIII(SO4)2·12H2O may therefore betaken as an almost positive indication that such element has no alum-forming power whatsoever."



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[Edited on 7-8-2012 by Poppy]




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[*] posted on 8-7-2012 at 09:26


At least one pleasant surprise: the neodymium sulphate that was hot precipitated yesterday had partly crystallised as the red octahydrate:




(the crystalline matter is about 5 cm across)

But there’s also some of the ‘sandy’ variety. I guess with much patience that could be dissolved in ice cold water and then by gradually taking up the temperature the octahydate might form.

Poppy:

Note that these Nd/alkali metal double sulphates aren’t really alums: they lack crystal water for that.

I’ve seen Chinese suppliers offering MOQ of 1 kg for Nd. But the price of REs is likely to go down further before they go back up again, IMHO… Large 'Chinky' finds, you see. Lucky barstools!

For spot FOB prices see also this:

http://www.metal-pages.com/metalprices/neodymium/

[Edited on 8-7-2012 by blogfast25]




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[*] posted on 8-7-2012 at 09:46


Why you growing fat crystals full of water and other double salt forming elements at all?
You making us jealous !!!

Just a question: Can you change color of those larger crystals too???




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[*] posted on 8-7-2012 at 10:30


Quote: Originally posted by Poppy  
Why you growing fat crystals full of water and other double salt forming elements at all?
You making us jealous !!!

Just a question: Can you change color of those larger crystals too???


The real expert on crystalline neosulphate hydrate is 'Wizzard', he's grown some real whoppers, a couple of pages back!

The hydrate is much more colour stable than anhydrous Nd salts. The trifluoride for instance changes dramatically from incandescent to save bulb light.




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[*] posted on 8-7-2012 at 20:55


I've never seen that bright red color! All I have is purple/pink (depending on lighting)... But the pink is beautiful. What lights do you use? Maybe particulate size affects color slightly? I know the smallest crystals of the substance are blue instead of purple, I have not bothered to gauge them under 'pink' lighting conditions.
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[*] posted on 9-7-2012 at 05:15


I don't worry too much about the colour: too subjective; lighting, camera, mass effects etc.



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[*] posted on 9-7-2012 at 10:14


I tried taking pictures of my crystals in as many light sources as possible- The neodymium sulfate is so pretty under so many different lights!
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