Sciencemadness Discussion Board

palladium extraction

wal1978 - 2-8-2012 at 14:45

hello ppl...

i was wondering if there is anybody here who can help me on my quest..

i have a powder mixture containing the folowing metals..

FE
Pd
Zn
Pb
Cu
CR
Mo

my problem is that i want to extract the palladium..
but because there are so many metals in this stuf i don´t know what methode to use...

anyone got a good idea:)

Gibberator - 2-8-2012 at 15:12

Dissolve away the more reactive metals with basic mineral acids, then hypothetically you should only be left with Pd but just in case dissolve away whatever is left with aqua regia. When everything is dissolved, precipitate the Pd with NH4Cl. You should be left with NH4PdCl6, which can be decomposed into Pd sponge upon calcining.

wal1978 - 2-8-2012 at 15:14

what acid do you think is best to use

Gibberator - 2-8-2012 at 17:17

Well HCl will get the iron and zinc, I can't seem to remember Chromium and I haven't really done much with Molybdenum but if HCl won't work for them then I'm sure HNO3 would, and it will also get the Lead and Copper. Just make sure that you don't use both at once, if you do you'll dissolve the Palladium.

elementcollector1 - 2-8-2012 at 19:08

HCl will work great with chromium if you leave it alone for a while (needs to break that protective oxide layer). Molybdenum can apparently form chlorides, but Wiki is a little hazy on this. So:
-Dissolve in HCl.
-Filter precipitate.
-Dissolve in HCl/HNO3 (aqua regia).
-Precipitate out ammonium-palladium complex with NH4Cl.
-Calcine at 400C for 1-2 hours.
-Remelt palladium if you want a button, otherwise you have gray sponge.
Incidentally, where did you get such a mix of metals?

weiming1998 - 3-8-2012 at 04:10

Quote: Originally posted by wal1978  
hello ppl...

i was wondering if there is anybody here who can help me on my quest..

i have a powder mixture containing the folowing metals..

FE
Pd
Zn
Pb
Cu
CR
Mo

my problem is that i want to extract the palladium..
but because there are so many metals in this stuf i don´t know what methode to use...

anyone got a good idea:)


Don't use nitric acid. Palladium dissolves in it. Iron and zinc can be easily dissolved with hydrochloric acid and lead with hot, concentrated hydrochloric acid. Wikipedia says that chromium dissolves in hydrochloric acid too. Molybdenum is a bit different, this site says that it dissolves in hot, concentrated sulfuric acid (http://www.fq.uh.cu/dpto/qi/images/stories/pog/pag/ino2/Grup...), but maybe the palladium will get attacked as well. You can also try oxidizing the metal and then trying to dissolve the acidic oxide in alkali (palladium doesn't oxidize easily). Copper can be complexed away by ammonia and hydrogen peroxide.

blogfast25 - 3-8-2012 at 05:08

Quote: Originally posted by elementcollector1  

-Precipitate out ammonium-palladium complex with NH4Cl.


Palladium does not form such an insoluble complex, IIRW. The fact that Pt does ((NH4)2PtCl6) is a way of separating Pt from Pd, as evidenced by Pd's discoverer, Wollaston.

After eliminating everything else with hot, 37 % HCl, it should be possible to separate Pd and Mo with nitric acid because Mo will form an acid insoluble oxide.

[Edited on 3-8-2012 by blogfast25]

wal1978 - 3-8-2012 at 11:11

Thanx For THE super info ppl...:):)

So let me see of i got this richt

1 dissolve in warm (60C) HCL wait 1 hour. - removes EF,Zn,Cr,Pb
2 filter
3 dissolve in HNO3 wait 1 hour. - removes Cu
4 filter
5 dissolve in HCL/HNO3. - dissolves the palladium leaving Mo as a acid insoluble oxide
6 Filter but this time Save the solven
7 Precipitate out ammonium-palladium complex with NH4Cl.
8 Calcine at 400C For For 1 or 2 hours

Let me knowe of i got it richt:D

Greetzz to you all...:cool:

Fleaker - 3-8-2012 at 11:16

Palladium does in fact form a very insoluble complex (please see my precious metals reclamation thread). And it's not a very effective way of separating Pt from Pd (that'd be DMG, or else S/X).

Hot concentrated sulfuric acid dissolves both palladium and rhodium (and silver for that matter).

Frankly, I would pre-digest in 25% hot HCl, filter, and treat the residue with aqua regia, filter it, and then add a small quantity of sulfamic acid to destroy free nitric acid (this conveniently makes sulfuric acid as byproduct, thus precipitating any lead as PbSO4). At that point, concentrate it down and precipitate it with a warm saturated solution of dimethylglyoxime in caustic soda (to which some DMSO has been added). Chill the solution, filter well, and rinse with cold 10% w/v ammonium chloride and 5% v/v HCl solution. That precipitate can be ignited in a quartz tube to give 99%+ Pd or it can be boiled in aqua regia to give Pd(IV)/Pd(II) and then the DMG precipitant can be used to get 9999 fine Pd.


If you need any help, let me know. We do this every day.


[Edited on 3-8-2012 by Fleaker]

[Edited on 3-8-2012 by Fleaker]

wal1978 - 3-8-2012 at 11:25

@fleaker

Can you put this in simple steps For me
:):):)

I'm just à amateur at this

Fleaker - 3-8-2012 at 11:45

Yes:


1. Remove HCl-soluble metals in a 5-6 h digestion with 25% HCl at 60*C; add just a pinch of sodium sulfite every hour to make sure that no free chlorine is formed. If there's MnO2 or other gunk, just used 30% sulfuric acid and keep the heat at 50*C.
2. Filter the hot solution (if you cool it, crystals of other metal chlorides will ruin filtration). Treat filtrate with caustic soda to pH 9.5 and let the base metals separate out.
3. The filter residue can be whole sale digested in aqua regia or in HCl/Cl2 or HCl/Br2 (this works very well for Pd).
4. Add sulfamic acid crystals (until no more nitrous oxide bubbles are formed) to the hot solution.
5. Filter the solution at room temperature.
6. Precipitate the filtrate with DMG/NaOH. Make sure it is not basic when finished and pH is still less than 1.5.
7. Filter voluminous yellow DMG precipitate.
8. Digest this precipitate in hot aqua regia (not boiling, but just below). Make sure you titre in the nitric acid so that it does not all run away on you.
9. Add small amount of sulfamic to kill nitrates and reduce this solution to a syrup. At this point, you can repeat Step 6 and then just ignite the Pd under H2, or you can try the method outlined below.

10. Add ammonium hydroxide and let it steep for some time, bring pH to 9, filter out base metal hydroxides that accompanied first DMG drop (it is very hard to get DMG clean b/c it is very voluminous and fluffy!), then re-acidulate until pH is 2-3.5 with HCl.
11. Filter the vivid yellow diamminepalladium (II) chloride, and rinse with cold ammonium chloride solution.
12. Add this filtrate to 1 L of water for every 100 g of Pd and add 50 mL concentrated ammonium hydroxide.
13. Add sodium formate crystals to the hot solution (place inside another container) and hold at 65-70*C for several hours. This will make fine Pd in excess of 9995. The filtrate will be clear, rinse the Pd with DI water and then dry at 180*C for 5 h and you have fine Pd sponge.




blogfast25 - 4-8-2012 at 10:41

Quote: Originally posted by Fleaker  

13. Add sodium formate crystals to the hot solution (place inside another container) and hold at 65-70*C for several hours. This will make fine Pd in excess of 9995. The filtrate will be clear, rinse the Pd with DI water and then dry at 180*C for 5 h and you have fine Pd sponge.



How does sodium formate (the sodium salt of methanoic acid) act as a reducing agent here?

Fleaker - 5-8-2012 at 06:46

Sodium formate is a great reducing agent for both Ag, Pd, and Pt. It produces CO.


blogfast25 - 6-8-2012 at 05:05

Quote: Originally posted by Fleaker  
Sodium formate is a great reducing agent for both Ag, Pd, and Pt. It produces CO.




Aha. As such could it be used to separate Cu and Ag in sterling silver? You seem to have suggested so elsewhere. The separation by their chlorides proved messy, largely due to the light sensitivity of AgCl. I ended up reducing the silver ammonia complex with glucose syrup.

And would formic acid work? They sell it here in the UK as a 40 % solution for descaling kettles, boilers etc. Quite cheap too... Of course it could be easily neutralised with NaOH/KOH.

[Edited on 6-8-2012 by blogfast25]

[Edited on 6-8-2012 by blogfast25]

plante1999 - 6-8-2012 at 06:37

Blogfast a common procedure to remove Cu from sterling silver is to dissolve the sterling silver in nitric acid till saturation than add copper sheet. After some time a crust of silver will be formed on the copper and the copper content of the silver is greatly reduced.

2AgNO3 + Cu -) Cu(NO3)2 + 2Ag

blogfast25 - 6-8-2012 at 08:27

Quote: Originally posted by plante1999  
Blogfast a common procedure to remove Cu from sterling silver is to dissolve the sterling silver in nitric acid till saturation than add copper sheet. After some time a crust of silver will be formed on the copper and the copper content of the silver is greatly reduced.

2AgNO3 + Cu -) Cu(NO3)2 + 2Ag


Yes, plating is well known to me. Not ideal for 100 % separation though: silver that coats copper sheet isn't so easy to remove without removing some copper too.

Fleaker - 6-8-2012 at 12:45

The sodium formate method works excellent for preparing 9995+ pure silver, with washing. It must be substantially free of PGMs, however, or it will be contaminated and only fixed by electrolytic parting. I recommend building a miniature Thum cell for that purpose.


http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t...


blogfast25 - 6-8-2012 at 12:52

Thanks, Fleaker. Any particular pH requirements for the sodium formate method?

Ooops, it says so in the linked thread. My bad.

[Edited on 6-8-2012 by blogfast25]

wal1978 - 7-8-2012 at 13:54

Can any one tel me whats THE best way to make aqua regia

Thnx....

Gibberator - 8-8-2012 at 20:02

May I suggest that if you're not even sure the how to prepare aqua regia then starting with a precious metal recovery isn't the best idea for you. Just my opinion.

Mailinmypocket - 9-8-2012 at 05:14

Quote: Originally posted by wal1978  
Can any one tel me whats THE best way to make aqua regia

Thnx....


I searched on google and found tons of results, all of them virtually identical for the preparation of aqua regia. Google this: "aqua regia preparation"

mockpc - 28-3-2019 at 19:18

Hi All,

I am having A pure Palladium Solution (with acetic acid and propylenediamine in it). I tried to use DMG to precipitate it. It form white precipitation and I am not sure if it is Pd Complex. Anyone have any idea hot to extract the Pd. Thank you in advance