hi i am on my way to an ounce of recovered gold from electronic scrap, when i get there i want to re refine all of it to get the purity as high as i can and I wanted to know what the best method would be. Should I just re do the aqua regia process or should I melt it with 3 ounces of silver and process it like karat gold in nitric first then AR
re refining
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I would wash well incenerate and re-refine the gold powders.
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Yep---what butcher said, although there should be no need to incinerate, assuming you have washed the gold properly, and rinsed it well. Incineration wouldn't serve much of a purpose for re-refining gold powder.
If you inquart, you start over, removing base metals. By re-dissolving the precipitated and WELL WASHED powder, you have already eliminated the vast majority of the contaminants. Therefore, when you precipitate the re-dissolved gold, there is far less garbage present to be dragged down by the gold. Net result is an improvement in fineness, assuming you practice good shop hygiene and have clean and good work habits. Make sure all of your vessels are very clean, and don't melt in a dirty dish. Make it one that has never been used for anything but PURE gold.
Harold
If you inquart, you start over, removing base metals. By re-dissolving the precipitated and WELL WASHED powder, you have already eliminated the vast majority of the contaminants. Therefore, when you precipitate the re-dissolved gold, there is far less garbage present to be dragged down by the gold. Net result is an improvement in fineness, assuming you practice good shop hygiene and have clean and good work habits. Make sure all of your vessels are very clean, and don't melt in a dirty dish. Make it one that has never been used for anything but PURE gold.
Harold
Irons
Well-known member
Harold_V said:
Unless you knew there was some Pd contamination of the Gold. Incineration would Oxidize some of the Pd to PdO, which is soluble in HCl or HBr.
...but, then, it would have to be re-refined anyway.
qst42know
Well-known member
What would the preferred method be to eliminate Pd?
Incinerate to oxidize or inquart?
I have some powder twice refined and rinsed properly yet remains quite dark. The source material was gold filled but a significant portion of which was white gold filled. I suspect palladium but I don't have any DMG yet.
Incinerate to oxidize or inquart?
I have some powder twice refined and rinsed properly yet remains quite dark. The source material was gold filled but a significant portion of which was white gold filled. I suspect palladium but I don't have any DMG yet.
Irons
Well-known member
qst42know said:
If you inquart, the Silver will carry the Palladium with it when you part it with Nitric. If you incinerate it to around 550 Deg. C., let it cool and treat it with HCl, the solution will turn Yellow within a short time, depending on the contamination. If it stays clear, there is likely little Pd contamination. Iron could also be the culprit, since it will alloy with Gold. It will also give you a yellow solution.
Hoke says 800 Deg to oxidize Pd, but other sources indicate that the oxide disassociates around 600 Deg. C. back to Pd and Oxygen.
It seems strange that the Gold would still be contaminated after being refined twice.
qst42know
Well-known member
The weather is going to keep me from this for a while.
