Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

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Gold cyanide precipitation with acidic copper (I) ion (1 reply and 1 comment)

Ron G
6 years ago
Ron G 6 years ago

I read David's excellent article Jan-2017 on various methods of gold recovery from cyanide leach here: https://www.911metallurgist.com/cyanide-chemistry-gold-extraction/ 

I am a gold electroplater and was particularly interested in the cuprous ion technique which, as David wrote, drops a gold (I) cyanide-copper (I) cyanide insoluble double salt AuCuCN2. I happened to stumble onto this reaction myself in 2014 after reading that copper (I) could precipitate AuCN, which is my gold salt that I could re-use. Obviously I was disappointing when found insoluble copper contaminated the precipitate. I then shot for using the method to reclaim gold metal out of old plating solutions but did not have time to verify the yield and did not know how to effectively deal with the AuCuCN2. David's article helped a lot with those two questions. 

My questions now are:

  1. Is the copper (I) method also effective at high yield with gold (III) cyanide?
  2. Is there an optimum free cyanide required to achieve highest yield precipitate?
  3. Is there an optimal PH or temperature for the reaction's yield or floc of precipitate? 
  4. Have there been attempts at separating the gold and copper cyanide after washing the precipitate?
Ron G
6 years ago
Ron G 6 years ago

Has anyone ever tried to drop AuCN from cyanide leach using persulfate (ammonium peroxydisulfate)?  If so what was the yield?

T
tesaygo1
6 years ago

Hello Ron, here in our countroy we use NaCN sodium cyanide to extract the gold from the ore. We first adjust the pH to 10.0 the higher the pH the slower i can dissolve gold but pH lower than 9.3 is poisonous. So just stable your pH to 10. About the concentration of cyanide to obtain high recovery rate we use 0.5% NaCN concentration for oxide ore, and 1% for sulfide ore. We run it for 24h in a agitator motor. This way is use to our country.


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