PGM Recover & Refining: Unknown green powder precipitated

[ZiegenSauger]

Greetings!

I have 3/5 Oz of incinerated material (filter papers, left over precious metals from unsuccessful processes mixed with chemicals) I am processing.
What I did so far (Stannous test performed after each of the steps below):
(1) Boiled in HNO3 diluted in water - liquid solution set aside separated from this process
(2) Boiled solids in HCl + H2O2 - precipitated Au with SMB and PGM with NH4Cl and NaClO3
(3) Boiled remaining solids in HNO3 diluted in water
(4) Boiled remaining solids in HCl + NaClO - precipitated Au with SMB and PGM with NH4Cl and NaClO3
(5) Boiled remaining solids in Aqua Regia - precipitated Au with SMB and PGM with NH4Cl and NaClO3
(6) repeated (5) for remaining solids
(7) repeated (4) for remaining solids
(8) All leftover solutions were reduced, and remaining syrup tested for Au and PGM (positive for Pt)
(9) Dropped precious metals with Zn
(10) repeated (5) and (4) for remaining solids - Stannous positive for Pt only
(11) Dropped precious metals with Cu
(12) Boiled remaining solids in HCl + NaClO - precipitated Pt with Cu

After (12), during wash up, there was a green precipitate in the filter (consider I filtered the main solution and after I filtered the leftover solution again). In the main solution filter, only the typical off-black brick red Pt precipitation.

Please see pictures below:
First picture shows all the solids after (12) cooking on 500mL of distilled water and 50mL of HNO3
Second picture shows last HCl + NaClO boil clean up (after 12) of the very last remaining incinerated solids. Besides the colour, Stannous is positive for Pt still. I plan to precipitate later today, will try DMG.

What the green powder might be? It does not dissolve in HCl. It does not dissolve in diluted HNO3.

Thank you in advance.

 

[ZiegenSauger]

Greetings!

I finish the process of separation and first round of refining the batch I referenced to before.

O obtained a minuscule quantity of Pd and a surprising quantity of Pt.

For the Pt, during the evaporation and filtering, I noticed some green powder mixed with the filtered Pt:


The first filter in the foreground, the other 3 filters contain the Pt after filtering once again.

I managed to recover /filter the green powder after processing the Pd through diluted Nitric:


Just out of curiosity if anyone can shed a light. The challenge for me is the case of the green precipitate coming out of solution together with PGM separation with Cu for example.

Just to reinforce, since I am a novice I cannot rule out any contamination, but the original material was processed in diluted nitric 2 times, and in Aqua Regia, HCL+H2O2, and in HCL+Bleach (separate rounds as I was going after the very last bit of PGM after each round and respective drop).

Thank you

 

[Lino1406]

To my knoledge, one chloride of iridium is green

 

[ZiegenSauger]

Woooooowooooowooooo!?!?!?!?

I have a staging process, if you will, to deal with left over solutions, after refinining, re-refning, evaporating, etc, etc:
First I add whatever come from a similar process, recovering same metal to a 500mL glass
Second I add a Cu coin in each glass
Third I recover whatever solids were dropped

Then I filter, wash the metals, store them and repeat with the liquid.

So after these pictures, I went to the second round, 5 of the glasses were AR leftovers where I recovered about ~1g of Au and about ~0.5g of Pd. Also approx. 1 g of Pt, where the green stuff accumulated.

Repeating the process, 3 jars yielded traces of, assuming, Pt powder (since the solution was diluted stannous positive) but two of them gave me even more green powder. I just dumped one of them in the stock pot since I was assuming it was excess copper or whatever.

I will recover the other and share here.

I am astonished, flabbergast. Let me see if I find references

BIG THANK YOU MATE.

 

[etack]

The pink residue on the filter shown in your picture series is the result of an incomplete reaction of your palladium salt with ammonia. It's chemical composition is the same as that of the yellow diamminepalladium(II)chloride, but it's structure is very different. The rose precipitate actually is a double salt, built up from [Pd(NH3)4]2+ cations and [PdCl4]2- anions, which is only very sparingly soluble in water. An analogous compound in platinum chemistry is the well known green Magnus salt.

saw this the other day might be helpful.

Pd purifying in pictures

https://goldrefiningforum.com/members/freechemist.16153/
This member was super helpful on this subject.

Eric

 

[ZiegenSauger]

This is great Eric, big thank you.
Even more now I continue to drop these greens, certainly I need more derailed, in depth information like this.

Much appreciated indeed!!!

Cheers

 

[etack]

Be careful freechemist is no longer with us due to these compounds.

Eric