# Question regarding Pt, Ir, and Pd salts



## tel (Nov 25, 2014)

So I have a solution containing Pt, Ir, and Pd, from a material I dissolved in aqua regia. I've already extracted a mixture of ammonium salts from this (about 15g sponge post-calcined) but seem to be at a standstill now. At any rate, are any salts for these water soluble? Right now I have a solution volume of approximately 1.4L containing ammonium chloride (from the initial extraction), but when I evaporate to about 0.9L or so, solids begin to fall out of solution with a color matching that of the solution itself, and these solids dissolve quite readily in distilled water. I believe this is crystallization due to saturation of the solution below a certain volume, but I can't seem to extract any more Pt, Ir, or Pd from this solution even though there is still plenty left (verified via scanning). So I'm partly led to hope that these solids forming are some kind of water soluble salt.

Just learning as I go, any input is appreciated. Thanks!


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## FrugalRefiner (Nov 25, 2014)

The answers to all of your questions are in Hoke's book. You'll find links to the book in my signature line.

Yes, the salts are soluble in water. It is nearly impossible to get complete precipitation of the PGMs.

Hoke discusses it in more detail.

Dave


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## Lou (Nov 25, 2014)

Most likely PGMs entrained in the saturated solution of ammonium chloride that gets stuck into the crystals. Kinda like coloring rock candy. 

If you've precipitated the solution correctly, there's at most a few hundred ppm. On to cementation.


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## tel (Dec 2, 2014)

So these solids did end up being PGM salts. I calcined them and ended up with 3g of mixed Pt, Ir, and Pd. Thanks for the insight  as I was not aware that complex salts could be so easily water soluble. Learn something everyday.


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