# laminated platinum metal contaminated with palladium



## arthur kierski (Apr 3, 2011)

i sold 10grams of pt to my regular buyer-----when i went to sell a new lot,he told me if i could remake(the 10grams). The pt which (although it looked very nice) seems to be contaminated with palladium----
how one should re-refine this platinum? i have some ideas ,but i would like to know if someone have other ways of re-refining 
thanks 
Arthur


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## lazersteve (Apr 3, 2011)

How much Pd to Pt in the alloy?

In the future treat your mixed black PGM powders with several hot 35% HNO3 extractions until no more yellow color is seen in the acid to remove any Pd before melting the Pt powder. I learned this little trick from Lou and have been using it to clean my Pt every since: Thanks Lou!

Steve


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## arthur kierski (Apr 3, 2011)

thanks Steve and Lou(as he gave you the tip on hno3washing)--------the alloy should not have more then 10%pd
Arthur


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## arthur kierski (Apr 6, 2011)

i received back the 10grams to re -refine---
it is in hot ar for several hours(boiling)---the ten grams is now 2grams and the solution is red (not yellow-platinum) and the stanous test gives red ,indicating rhodium --no pd----i think that the laminated platinum was contaminated with rhodium and not pd---- i am adding more ar to reach complete dissolution of the ten grams----i will have a red solution(in my mind of pt-rh and perhaps traces of pd) which i will denox and then i think add saturated kcl to precipitate the pt and leave rh and traces of pd in solution----
am i correct in my thinking? or am i making some mistake?
thanks for any remarks and help
Arthur


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## Lou (Apr 6, 2011)

The KCl trick only works if it's +2 platinum and the pH isn't lower than 4 or 5.

Lou


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## samuel-a (Apr 6, 2011)

Lou 

What is the advantage of using KCl over Ammonium Chloride ?

What is the process exactly using KCl ?
I would love to find more info of that technique.

As far as i could research, the process involves several reductions stages using hydrazine, alcohol and NaOH...


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## Lou (Apr 6, 2011)

There is no advantage if the Pt is in +4. It only works if it's Pt +2 and that needs reduced halfway with hydrazine or borohydride. It's solubility is more than that of ammonium hexachloropalladate so it's not a great way to go.

As for what you mention, warm ethanolic KOH solution (or NaOH) solution will reduce the platinum as it oxidizes the alkoxide to an aldehyde.


Lou


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