Sciencemadness Discussion Board - Rare earths from Gadolinite (Ytterbite)

Rare earths from Gadolinite (Ytterbite)

TheChemiKid - 21-12-2013 at 04:31

I was wondering if there was any way to salvage rare earths(Cerium, Lanthanum, Neodinium, Yttrium), or any other metals (Beryllium) from Gadolinite. The chemical formula is (Ce,La,Nd,Y)₂FeBe₂Si₂O₁₀.

Random - 21-12-2013 at 04:46

Beryllium is very toxic to mess with IIRC and lanthanides are very hard to separate correctly.

There are ways to do it though, now how much of it do you have? Depends if it would be profitable, for small quantities nope.

TheChemiKid - 21-12-2013 at 04:56

I can get lots of it. ~200g

blogfast25 - 21-12-2013 at 05:43

Quote: Originally posted by TheChemiKid

I was wondering if there was any way to salvage rare earths(Cerium, Lanthanum, Neodinium, Yttrium), or any other metals (Beryllium) from Gadolinite. The chemical formula is (Ce,La,Nd,Y)₂FeBe₂Si₂O₁₀.

Worth searching for, although your sample of Gadolinite may be worth more than a mass of undifferentiated REs.

At a glance I'd say:

1) Crush and grind finely, then fuse with twice the weight of fine KOH for about 30'. This destroys the mineral's structure and turns the silicate into a more manageable form.

2) Recover the frit, crush and grind it and dilute it with loads of water to reduce pH as much as possible, to 8 - 9. Allow to stand overnight. All will be present as hydroxides. Then filter and recover filter cake.

3) Recover Be(OH)2 from filter cake by soaking in a saturated solution of NaHCO3, in which it is soluble. Soak overnight, stirring from time to time.

4) Filter and wash filter cake with saturated NaHCO3 solution, then with a small amount of water. Filtrate contains the Be2+ as a carbonate complex. Be compounds are toxic but elementary precautions suffice. The Be can be recovered by carefully neutralising the filtrate with HCl, then boil off the CO2, then add NH3 solution to precipitate as Be(OH)2.

5) Filter cake contains REs, Fe and silica. Dissolve in hot, 37 % HCl for prolonged period (by reflux e.g.). Fe and REs enter solution. Filter off insoluble silica.

6) Then separate K and Fe from REs the usual way, for instance as sulphates or double sulphates with potassium sulphate. If Fe is present as Fe(III) (likely) then this needs to be done in acidic conditions (pH < 3) to prevent Fe(OH)3 from precipitating.

This is just an outline. I haven't actually done this myself. It's based on similar ore analysis of silicate based ores.

[Edited on 21-12-2013 by blogfast25]

TheChemiKid - 21-12-2013 at 07:39

Thanks, this is great. So you don't worry about the price, I know of the Ytterby mine, which is near me. It is not in operation anymore. I can find LOTS of Gadolinite there.

Brain&Force - 21-12-2013 at 09:36

You can get at least three rare earths out - cerium, europium, and terbium. All three have a oxidation state other than +3. Cerium is the most straightforward, just add HNO₃ and cerium will precipitate. Terbium is much harder to oxidize to +4; the reaction often produces a mixed oxide (Tb₄O₇.) 68% nitric acid is sufficient to oxidize Tb³⁺, but the reaction is slow. As to europium, I have no clue, but it might help to know EuSO₄ is highly insoluble, similar to its barium analog.

Do you have a Geiger counter? There may be thorium in your sample (it tends to mix with the rest of the rare earths, especially thorium). Be sure to take necessary precautions.

TheChemiKid - 21-12-2013 at 09:39

I have already tested my samples, they have very low radioactivity.
I will still take all necessary precautions for Thorium and Beryllium.

[Edited on 12-21-2013 by TheChemiKid]

Brain&Force - 22-12-2013 at 22:34

I made a small mistake; thorium often mixes with cerium due to similar chemistry. However, thorium is the first to precipitate when pH increases, so it can be removed that way. Also note that most lanthanide sulfates dissolve more easily in cold water, which can help if you need to redissolve them or precipitate them. Heavier lanthanide sulfates are generally less soluble.

Here's how I would continue the procedure:

7) Dissolve sulfates in freezing cold water. Precipitate all of them with NaOH/KOH. Filter the oxides and heat them to oxidize any cerium(III) to cerium(IV).

8) Dissolve the oxides in weak nitric acid to prevent cerium dioxide from dissolving and terbium(III) from oxidizing, but allow everything else to dissolve.

I'm not entirely sure about terbium oxidizing to a mixed terbium oxide in 68% nitric acid. I'm already doing research on terbium, so I'll try to find some acid and figure it out. MrHomeScientist's video on terbium nitrate shows the product being formed. The reduction potential for terbium(IV) to terbium(III) is +3.1 in acid solution and +0.9 in basic solution.

blogfast25 - 23-12-2013 at 05:19

Quote: Originally posted by Brain&Force

7) Dissolve sulfates in freezing cold water. Precipitate all of them with NaOH/KOH

Isn't really necessary. Just treat the freshly precipitated sulphates with strong ammonia, they convert to the even more insoluble hydroxides almost immediately. Also, ammonia reduces occlusion, with respect to NaOH. Works too on the RE/K double sulphates.

Dissolving RE sulphates in iced water takes forever.

[Edited on 23-12-2013 by blogfast25]

blogfast25 - 17-1-2014 at 13:46

Gadolinite-Y and White Cloud Pegmatite: some samples

Here are some samples of the rare mineral Y-Gadolinite (sometimes known as Ytterbite) with White Cloud Pegmatite that I obtained recently:

Detail of the larger specimen: the near-black, glassy Gadolinite can clearly be seen.

The samples were kindly donated to me by the University of New Orleans and originate from the South Platte district, Jefferson Co., Colorado (USA).

Chemically speaking Gadolinite corresponds to the empirical formula (Ce,La,Nd,Y)2FeBe2Si2O10. Depending on whether the prevailing Rare Earth Element is Ce (for Ce-Gadolinite) or Y (for Y-Gadolinite) the prefix changes to reflect composition.

The first problem will be to obtain some of the Y-Gadolinite, as free of Pegmatite as possible.

An initial test with heating a small piece in a maximum Bunsen flame and then quenching it in ice cold water yielded something that could be ground down quite easily (under water) but on drying the ground sample clearly contained both beige and black coloured grains. Presumably the beige is Pegmatite. I may have to use some form of panning to separate the two.

[Edited on 17-1-2014 by blogfast25]

bfesser - 17-1-2014 at 15:28

TheChemiKid, as I just noted in another topic (see below), collecting at the Ytterby mine is strictly prohibited (<a href="http://www.mindat.org/loc-3191.html" target="_blank">ref.</a>

. What blogfast25 said earlier may be true; if your gadolinite is actually from the type locality (the <a href="http://www.mindat.org/loc-3191.html" target="_blank">Ytterby mine</a> <img src="../scipics/_ext.png" />

, and was collected prior to the ban, I'd be interested in purchasing a specimen from you.

Quote: Originally posted by blogfast25

Worth searching for, although your sample of Gadolinite may be worth more than a mass of undifferentiated REs.

blogfast25, I wonder if you've seen my recent post on this subject, quoted below:

Quote: Originally posted by bfesser

Last night, I added a few new <a href="http://en.wikipedia.org/wiki/Rare_earth_mineral" target="_blank">rare earth mineral</a> <img src="../scipics/_wiki.png" /> specimens to my collection. Nothing too fancy, but they exhibit the expected radioactivity. I recieved a small specimen of <a href="http://en.wikipedia.org/wiki/Gadolinite-(Y)" target="_blank">gadolinite-(Y)</a> <img src="../scipics/_wiki.png" /> (also known as ytterbite), a specimen of <a href="http://en.wikipedia.org/wiki/Xenotime" target="_blank">xenotime</a> <img src="../scipics/_wiki.png" /> in fluorite, a specimen of xenotime in quartz, and a specimen of <a href="http://en.wikipedia.org/wiki/Samarskite-(Y)" target="_blank">samarskite-(Yb)</a> <img src="../scipics/_wiki.png" />; all from the <a href="http://www.mindat.org/loc-66693.html" target="_blank">South Platte Pegmatite District, Jefferson Co., Colorado</a> <img src="../scipics/_ext.png" />. A rough measure of the samarskite showed ~3.5×103 CPM [details for other minerals on Flickr]. I'm very pleased with these new additions to my collection, but I'm still hoping to get a specimen of gadolinite from <a href="http://www.mindat.org/loc-3191.html" target="_blank">its type locality</a> <img src="../scipics/_ext.png" /> sometime in the future—which may prove difficult, as collecting from the quarry site has been prohibited since the 1970's.

I've taken and uploaded <a href="http://www.flickr.com/photos/35937732@N02/sets/72157639665100206/" target="_blank">some photos</a> <img src="../scipics/_ext.png" /> of my collection radioactivity related items, including my new mineral specimens. I've also uploaded [a] short video to YouTube, <a href="http://youtu.be/7QmuvC0-F2M" target="_blank">demonstrating the modified firmware</a> <img src="../scipics/_yt.png" /> on my MightyOhm.com kit along with the activity of my samarskite-(Yb).

I was just given a bit more gadolinite-(Y)—in my experience, it's a postfix—tonight, as a gift. While the chemistry is, no doubt, interesting, I can't say that I'm in favor of the destruction of mineral specimens for the (unlikely to succeed) isolation of rare earth metals. Surely you could obtain some rough, ugly, dirty ore rather than smashing viable mineralogical specimens? If you must proceed; please be kind enough to amply document your experiments and share the details.

[Edited on 18.1.14 by bfesser]

blogfast25 - 18-1-2014 at 06:20

bfesser: no, I didn't see that post.

The sample I'm currently treating wasn't worth keeping and will, after separating the Pegmatite, only amount to a few gram. I hope that'll be enough to show both Be and Y with some mini-chemistry. I'm onto it today and will of course report here.

I was very lucky to obtain these samples gratis, so I'd be very loathe to destroy the finest of them. But some of them are really not that interesting to look at.

[Edited on 18-1-2014 by blogfast25]

Edit:

The separation of the black Gadolinite and beige Pegmatite was remarkably easy. I used three plastic beakers, suspended the initial mixture in water, stirred it up, allowed most of the black material to settle, then decanted off the beige supernatant suspension. This was repeated a number of times, recovering also what dark material had flowed over with each partial separation. In about 15 minutes of fiddling the separation looked over 90 %.

After drying, 6.54 g of presumed Y-Gadolinite concentrate was thus obtained. It was mixed with 13 g of crushed KOH flakes and fused in a nickel crucible with lid for 15 minutes at medium high Bunsen heat.

The fused product looked a dark green colour but on adding water immediately reverted to reddish-brown. Using small amounts of water, mild heating and some elbow grease it was quantitatively transferred into a mortar and pestle and ground up, then transferred into a 500 ml boroglass beaker and diluted to about 500 ml.

15 ml 37 w% HCl was added with vigorous stirring, resulting in a paper pH of about 7. All components of the Gadolinite are now assumed to be present as solid oxides/hydroxides.

This suspension was allowed to stand for about 1 h, then about 300 ml of clear supernatant liquid was siphoned off and to the remaining 200 ml, 25 g of reagent grade NaHCO3 was added and the slurry stirred with slight heating to saturate the water with bicarbonate. This slurry will now be kept overnight on my laboratory radiator, stirring occasionally, to solubilise the Be(OH)2 as a carbonato complex.

The fused Gadolinite slurry, saturated with bicar:

[Edited on 18-1-2014 by blogfast25]

blogfast25 - 19-1-2014 at 10:21

1. Recovery of the beryllium

Allowing the bicar saturated slurry to stand overnight, stirring occasionally, caused the supernatant liquid to take on a pale yellow colour (while remaining clear).

Today this slurry was Buchnered (twice: ferric hydroxide can be a barstool to filter), the filter cake washed with 2 x 25 ml of saturated bicar solution and set aside.

To the clear, pale yellow filtrate, about 30 ml of 37 w% HCl was added to neutralise the bicar, during which the solution started to cloud over, then went back to clear when CO2 evolution stopped (a clear sign of an amphoteric being present). The CO2 was removed by repeated shaking in a plastic bottle. Then a good dollop of 33 % NH3 was added and the fluffy, flocculant Be(OH)2 dropped out, taking it’s time to settle (it’s very light).

The supernatant liquid had also become colourless, presumably the initial yellow colour was due to small amounts of colloidal Fe(OH)3. The Be(OH)2 precipitate shows a slight reddish tinge. Here it is:

2. Separation of silica from Fe and REE

Here’s the filter cake containing all hydroxides/oxides (except Be), prior to dissolution:

20 ml of HCl 37 % was added (twice the stoichiometric estimate) and it dissolved effortlessly on heating, except for the silica which manifested itself annoyingly as this slimy gel. I’ve had this before with Zircon and Beryl and the ‘Si(OH)4.nH2O’ is a royal pain in the *rse because it just doesn’t filter. So with a combination of filtering, decanting and quite a bit of ‘pardon my French’, most of the Fe + REE bearing liquor was separated from the gelatinous silica. I’m sure a small amount could be still be found in the filtrate. There has to be a better way…

This is it, prior to filtering, with the annoying gel as precipitate:

Another important observation was some insoluble black residue (not shown), which I presume to be unreacted Gadolinite.

3. Recovery of the REEs as sulphates

To the 200 ml of filtrate 20 ml of 98 w% H2SO4 was added, the solution turned amber. Cloudiness started immediately. Heating it to boil caused serious bumping, so I switched to a steam bath and reached about 95 C in about 1 h. A considerable amount of white, sandy precipitation, presumed REE sulphates collected at the bottom of the beaker:

I may or may not further purify these REE sulphates, depending on available time.

[Edited on 19-1-2014 by blogfast25]

Brain&Force - 20-1-2014 at 10:39

Just wondering, does the rare earth sulfate fluoresce at all?

blogfast25 - 20-1-2014 at 11:31

Quote: Originally posted by Brain&Force

Just wondering, does the rare earth sulfate fluoresce at all?

I haven't had a chance to isolate or purify it yet. Yttrium sulphate itself should not because it contains no odd 4f electrons. Of course there's more than Yttrium in there. I will definitely check this out.