Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

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History of gold refining. (2 replies and 2 comments)

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Vincent Cherico
4 years ago
Vincent Cherico 4 years ago

Hi, my name is Vin, and I am not a metallurgist. And have no idea what I am talking about. ? However I am writing an article which touches on the recovery of gold from jewelry scrap in the 18th and 19th centuries. Is there anyone out there that is versed in the history of scrap gold reclamation? If so I have some very basic questions on how it was done.

Thanks Vin

Mike
4 years ago
Mike 4 years ago
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The simple answer is that it is done the same way you process raw gold.   Combine it in to a pot and smelt it back.  If it is pure enough (18 caraet or higher) you often just melt it down (after manually removing jewels, etc.) and recast.

V
Vincent Cherico
4 years ago

Thanks so much for getting back to me. to be more specific it is the removal of gilding that has been applied to brass watch plates and and wheels. I have heard several different methods. The First was that the the parts were thrown together in a crucible and melted. To me this seems like all you would end up with was gold with a high brass content. The second one was that the gilding was scrapped of the brass and that it was then soaked in aqua regia to remove what little brass remained then refined by fire. The third was that at some point in the 19th century a reverse form of electroplating was used. My field of expertise is Historical Horology. So please forgive the ignorance of my questions Thanks Vin

T
Todd H
4 years ago
Todd H 4 years ago
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The most common method to remove copper from gold is to do electrorefining.

The coper is digested in sulfuric acid - the gold remains undissolved and forms a sludge.  The coper is electrowon from the solution and the gold sludge is melted and refined.

Aqua regia dissolves both gold and copper so that method would only work if you had a clean scraping.

Melting it all together could be done but it is hard to remove copper by refining this way as they form a  very nice alloy!  See this book

De re Metallica

Regards

 

 

Todd Harvey - Global Resource Engineering http://www.global-resource-eng.com

V
Vincent Cherico
4 years ago

Thank you so much for your input!

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