Recovering Palladium

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100tific

100tific

Active member
Joined
Sep 1, 2023
Messages
34
Location
Córdoba
hi guys,
i was profilling the recovering palladium method and i found some problems.
I have an alloy wich has gold, silver and palladium. i inquarted with copper to low the silver concentration down to 8% and laminate de ingot. Then i dissolved the alloy in AR and i filtered to separate the AgCl. I heated the pregnant solution to have a syrup and i added a little bit of HCl to remove all the HNO3. Then , i added ammonium chloride to my hot pregnant solution and then i added sodium chlorate.
i obtained my red powder of ammoium tethrachloropalladate , BUT (and now my problem) i also have another precipitate.
I show you two pictures about it.
i also had another solid with black color. I saw it in the XRF and it shows palladium 925 and gold 73. I dont know why it forms it.
Could it be for the excess of reactives? it is not ease to know when is the final point of the reaction
Maybe it is for the temperature? do you know what is the best temperature for this reaction?
how can i recover this palladium and gold from the black powder without Ar and ammonium chloride and sodium chlorate again.. ? there are any form to wash it?
i hope you can help me.
Thank you so much.
 

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100tific said:
hi guys,
i was profilling the recovering palladium method and i found some problems.
I have an alloy wich has gold, silver and palladium. i inquarted with copper to low the silver concentration down to 8% and laminate de ingot. Then i dissolved the alloy in AR and i filtered to separate the AgCl. I heated the pregnant solution to have a syrup and i added a little bit of HCl to remove all the HNO3. Then , i added ammonium chloride to my hot pregnant solution and then i added sodium chlorate.
i obtained my red powder of ammoium tethrachloropalladate , BUT (and now my problem) i also have another precipitate.
I show you two pictures about it.
i also had another solid with black color. I saw it in the XRF and it shows palladium 925 and gold 73. I dont know why it forms it.
Could it be for the excess of reactives? it is not ease to know when is the final point of the reaction
Maybe it is for the temperature? do you know what is the best temperature for this reaction?
how can i recover this palladium and gold from the black powder without Ar and ammonium chloride and sodium chlorate again.. ? there are any form to wash it?
i hope you can help me.
Thank you so much.
Click to expand...
I think it is better to precipitate the Gold out first.
Now you obviously drag some of the Gold down during the separation.
How did you treat the Gold?

Edit to add:
To remove traces of Pd use DMG
 
According Hoke, it is like i did.
now i took a small quantity of this black powder and i added a few drops of sodium chlorate more, because i thought the red compound is ammonium hexachloropalladate and the black compound is thetrachloropalladate... so maybe it need more quantity of an oxidant like sodium chlorate is.
it changed from brown to red ( at this moment i had to filter it and finish) but then i heat it and another change happened. the red powder now disappeared and now i have a orange liquid... i think it is palladium chloride :(
now i dont know how to come back to the red powder
 
100tific said:
According Hoke, it is like i did.
now i took a small quantity of this black powder and i added a few drops of sodium chlorate more, because i thought the red compound is ammonium hexachloropalladate and the black compound is thetrachloropalladate... so maybe it need more quantity of an oxidant like sodium chlorate is.
it changed from brown to red ( at this moment i had to filter it and finish) but then i heat it and another change happened. the red powder now disappeared and now i have a orange liquid... i think it is palladium chloride :(
now i dont know how to come back to the red powder
Click to expand...
The point of the Sodium Chlorate is the convert the salts to their highest valency so it can be precipitated with Ammonium Chloride.
The red powder can be heated slowly (Calcining) until it is converted to metal, maybe the black too.
Or redissolved and run through an Formate reduction at which point it will be in metal form.

I really hope you have proper fume hoods and PPE for this.
PGM salts are exceedingly toxic.
The best would be to avoid them all together or drop them by Cementing on Copper.

Maybe the best course of action would have been dissolving the Pd and Ag in Nitric, dropped the Ag as AgCl and then cemented the Pd.
 
Yes, i know, of course The red powder can be heated slowly (Calcining) until it is converted to metal, and yes, the black too. But i wanted a recovering, to separate both metals, not to get it together again... so i calcinated the red powder but not the black because it has Pd and Gold.

i dont know where was my fault at the recovering.
Could it be for the excess of reactives? it is not easy to know when is the final point of the reaction
Maybe it is for the temperature? do you know what is the best temperature for this reaction?
how can i recover this palladium and gold from the black powder without Ar and ammonium chloride and sodium chlorate again.. ? there are any form to wash it?

and yes, i have a proper fume hoods and PPE for this.
and i know PGM salts are exceedingly toxic.
Nothing answer my questions.
thanks.
 

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