# Problem with Pd recovery



## Marcel (Oct 20, 2012)

I recovered some Pd from MLCCs.
I used used AP to dissolve the powder that was left over.
I precipitated with copperpowder and got a brown powder.
Cleaning that with HCl and hot water I went to melting it with the torch
Result was a dull and grey looking button, different from my last button that was made from the foils and was a nice dark silver shiny button.
So I dissolved that button using nitric 53% (yes tried that out) instead of hot AP.
The result was precipitated using zinc powder.
Now I have two samples, one that has been dissolved with hot AP then precipitated with copperpowder (right) and one very black powder that was dissolved by nitric, then precipitated with zinc (washed with hot water, then HCl). 

As a cleaning step, I added HCl to both glasses.
As you can see the solution to the left started to become red and SC test was strongly possitive for Pd.


On the right side that brown poder has created a green solution (CuCl I suppose) and SC is negative for PMs. 


Can someone tell me why the powder on the left is going into solution, as the black powder stays using HCl? To my understanding this could only happen if there is no other metal present or the metal in the black powder is higher in then reactivity chart then Pd. Or have some nitric salts plus HCl formed AR?


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## samuel-a (Oct 20, 2012)

Marcel said:


> Or have some nitric salts plus HCl formed AR?



Marcel, You nailed it.

Getting rid of 100% left over nitric/nitrates is acheived only by inciniration.


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## lazersteve (Oct 26, 2012)

Pd oxides are soluble in HCl alone as is finely divided Pd sponge to some degree.

Steve


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## Lou (Oct 26, 2012)

lazersteve said:


> Pd oxides are soluble in HCl alone as is finely divided Pd sponge to some degree.
> 
> Steve





Hydrated Pd oxides are soluble in HCl alone. 

Dead burnt oxide (say from reduction of catalyst) are not soluble in HCl. We formate those and then redissolve.


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## johnny309 (Oct 28, 2012)

Purify you Pd.....simple....HCl+bleach(NaOCl)....then ammonium chloride(it is used as a flux in weldind,so it is avaible)....then more NaOCl(so ...ACE as a brand in Europe) for precipitation.
The orange powder must be calcinated(over 400C...an electric stove is more than you need)....then melt(a little hard).
For more details(and the final product....my own)....please visit :


http://goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=15444


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