Possible Iridium precipitate

[Aurumlife]

Hi guys. While attempting to refine palladium from dental scrap I dissolved palladium black in aqua regia and separate platinum by adding ammonium chloride solution I had this precipitate of salts of a raspberry color. I expected the color to be yellow. Could that possibly be Iridium salt?

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[nickvc]

I don’t believe iridium is used in dental alloys, I had a similar experience some years ago and I believe the culprit was cobalt.

 

[Aurumlife]

From what I heard it is used in threaded pins. And I saw them when was preparing scrap for refining. Should’ve clipped them off before refining. Oh well… you live, you learn. Something new every time


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[Lou]

Unless the solution was heated sufficient to convert Pd(IV) to Pd(II), it is like a mixture of Pd/Pt chlorometallates.

 

[Aurumlife]

So in other words I might have possibly very little platinum (if any) in that solution. I was thinking that, considering the fact that palladium material was recovered from nitrates predominately with DMG and only a minor amount from further treatment of that dental scrap in AR. Ok, I will redissolve the precipitate and process it separately from the solution. Then will evaporate the excess solution and try to add ammonium chloride when ice cold again and watch what happens. Plan to reduce it then after redissolving Pd salt in AR with formic acid to the palladium sponge. Thanks for the comments guys. I really appreciate it. Working with PGMs is tricky but challenging and exciting.


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[Aurumlife]

It worked. My first palladium refining with formic acid. I kept that raspberry color precipitate separately and was trying to dissolve it cold HLC, didn’t work.

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