Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

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Cupelling Karat Gold (1 reply and 1 comment)

G
gbrideau
1 month ago
gbrideau 1 month ago

Hi forum members,

 

I can't seem to be able to find much information about cupelling karat gold, as in 10k rings, for example. At what temperature should I cupel a 10k gold ring? I've noticed a few posts mentioning that gold should be cupelled at a temperature between 1700f to 1850f but since this is below the melting point of gold, wouldn't the button freeze in the cupel before all the lead has been removed? Any help would be greatly appreciated. Thanks!

SmartDog
1 month ago
SmartDog 1 month ago

Mekting point of gold alloys varys by gold content.  While 24k gold melts at 1950 F.  Other assays melt lower.  See: https://www.kitco.com/jewelry/solders.html

 

G
gbrideau
1 month ago

Thanks for replying, SmartDog.
I understand that karat gold has a lower melting point due to the alloys but as the gold gets more pure with the process of cupellation, the melting point would rise. Thus my question, wouldn't the button freeze in the cupel before all the lead has been removed? Thanks again!

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