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

Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction 2017-03-23T09:50:58+00:00
  • To participate in the 911Metallurgist Forums, be sure to JOINLOGIN
  • Use Add New Topic to ask a New Question/Discussion about Hydrometallurgy.
  • OR Select a Topic that Interests you.
  • Use Add Reply = to Reply/Participate in a Topic/Discussion (most frequent).
    Using Add Reply allows you to Attach Images or PDF files and provide a more complete input.
  • Use Add Comment = to comment on someone else’s Reply in an already active Topic/Discussion.

THIOCYANATE GOLD LEACHING PROCESS (2 replies and 2 comments)

11 months ago
emanus 11 months ago

hello metallurgist;

please, what is the function of iron (Fe) in gold leaching process with thiocyanate as a Gold Dressing Agent composition?


11 months ago
David 11 months ago

The leaching of gold ores by acid solutions of thiocyanate produces two complexes, Au(SCN)2- and Au(SCN)4-.

The reaction involves oxidation. It is believed that the addition of Iron III is a good oxidant.

Trying to add oxygen is not a good option because the gold dissolution will be very slow.

Also the addition of iron tends to make more stable the thiocyanate.

11 months ago

That's interesting, David. Is this process actually used industrially? If so, can the Fe II be recovered and re-oxidised, giving iron the role of catalyst rather than reactant? Otherwise, it seems to me that using up multiple Fe atoms per Au atom could add significant cost and waste stream to the process..

11 months ago
David 11 months ago

The possible use of thiocyanate was studied the first years of the twenty century. The reagent was only evaluated in laboratory tests, but not in an industrial gold operation. During the dissolution of gold by iron, it was established that Fe III is reduced to Fe II, and the oxidizing of thiocyanate is promoted, producing (SCN)3- and (SCN)2, the reaction is fast and iron is not recovered, these SCN compounds are not very stable, this is one of the main disadvantages. Other point to comment is the effect of temperature, gold dissolution is better at high temperatures. It is easy to realize that to build a plant could involve a higher Capex and Opex than a regular cyanidation plant.

Marc LeVier
10 months ago

Newmont was granted a patent on use of SCN around 2010/11. Patent description is available but application is a narrow window.

Please join and login to participate and leave a comment.