Iodine/Iodide Gold Extraction - Cementing on Base Metals?

[spentfire]

Greeting everyone!

I've been doing quite a bit of Forum research on I₃^- stripping-extracting-leaching, and find the technique quite intriguing. However, my question is if I were to use this technique on gold plated pins, for example, what would keep the formed KAuI₄ from cementing back out as metallic gold on the surface of the base metals? I'm concerned that if cementation happens, and the metallic gold could be re-oxidized back to KAuI₄, which could then recement...ad nauseam...until either all of the base metal or available I₃^- was consumed.

I'm hoping that someone will say that the KAuI₄ complex is stable enough in an acidic medium not to cement out on just base metals, but without confirmation, my gut says that's not likely.

I hope that this question hasn't been asked and answered a million times, but I think I've followed due-diligence and read just about every post I could find on this topic (twice!).

I'm just looking for something new to try on pins, etc, besides the AP method

Thanks in advance!

Spentfire

 

[NoIdea]

Hello - From the little work i have done using this process, the gold will not ppt out on copper as long as the pH is low, below 6. Check out USPatiant 3957505 and USPatiant 4319923 which shows a couple of approaches.

Hope this helps.

Cheers

Deano

 

[spentfire]

Deano:

Thanks for the confirmation! I've looked through those two patents again, and they don't appear to mention anything about cementation, but I was worried I was missing something else.

Any recommendation for which precipitation scheme you like better (SMB, etc. versus high pH)? I like the idea of being able to reuse the stripper more than twice.

Thanks again!

Spentfire

 

[NoIdea]

Morning - I personally would choose the US3957505 as it removes all PM's and the iodine. This means your iodine is ready for a new batch. The other just adds extra liquid and chemicals to the digestion solution, it was a wee bit messy. :lol:

Hope that helps, and can you please let me know how you get on.

Cheers

Deano

 

[spentfire]

Deano:

Will do!

Spentfire