# Palladium refining problem



## Atto (Mar 17, 2014)

Hello ,

I would like some help to solve an unusual problem that happened in the refining of palladium.

I start with 200g of material, it dissolved normally in AR, I filtered the solution , added ammonium chloride to remove the platinum and filtered again.
With the solution I had the intention to form a yellow complex of palladium (NH3)2 Pd Cl2, adding ammonium hydroxide in solution , what should keep palladium soluble and then adding HCl to precipitate the complex. However, only with the addition of ammonium hydroxide the insoluble complex was formed! 
This compound has a similar (NH3)2 Pd Cl2 color, but is not soluble in ammonium hydroxide, and despite it reduced normally with sodium hydroxide and formic acid, after calcination it was with a different aspect of common palladium, with oily appearance. 
Another important point is that in the remaining liquid, after adding HCl, more insoluble complex was formed, and in this way the palladium obtained was in the usual color, was melted normally and presented the desirable purity.
Does anyone have any idea what may have happened ?

Thank you for your attention.


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## butcher (Mar 17, 2014)

My thoughts here, go towards Amphoterism?
I do not know that is what is going on but it sounds like it.
http://en.wikipedia.org/wiki/Amphoterism
http://employees.oneonta.edu/kotzjc/LAB/Complexation.pdf


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## freechemist (Mar 19, 2014)

Atto, you are asking for help


> I would like some help to solve an unusual problem that happened in the refining of palladium.



To me it seems that you have a palladium-*recovery*-, rather than a palladium-refining problem, probably in addition to a *platinum-recovery* problem. The most unusual thing I see, is the way in which you describe your experimental approach to some recovered palladium.

Based on the scarce and only very vague information you give us, I can only guess, that you tried to dissolve 200 g of some material (what material exactly?) in AR (how much HCl/HNO3; how was it done exactly?), probably containing some platinum and/or palladium. Then you filtered the mixture (was there any residue?), added ammonium chloride (how, how much?) to the filtrate, to remove Pt, filtered again (was there a residue on the filter; how did it look like?)... and so on....and so on, finally ending the procedure with something having an oily appearance (?).

Without much more detailed and precise informations about your processing, significant observations etc., I can not help you more. So, just let me do one guess: The "insoluble complex" obtained after addition of aqueous NH3 ("ammonium hydroxide") to the second filtrate may well be some ammonium hexachloroplatinate(IV), (NH4)2PtCl6, precipitated by ammonium-ions, formed in the reaction of NH3 with excessive acid in the whole reaction-mixture.


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