Gold cyanidation

Gold cyanidation (also known as the cyanide process or the MacArthur–Forrest process) is a hydrometallurgical technique for extracting gold from low-grade ore through conversion to a water-soluble coordination complex. It is the most commonly used leaching process for gold extraction.^[1] Cyanidation is also widely used in silver extraction, usually after froth flotation.^[2]

Production of reagents for mineral processing to recover gold represents 70% of cyanide consumption globally. While other metals, such as copper, zinc, and silver, are also recovered using cyanide, gold remains the primary driver of this technology. ^[1] The highly toxic nature of cyanide has led to controversy regarding its use in gold mining, with it being banned in some parts of the world. However, when used with appropriate safety measures, cyanide can be safely employed in gold extraction processes.^[3] One critical factor in its safe use is maintaining an alkaline pH level above 10.5, which is typically controlled using lime in industrial-scale operations. Lime plays an essential role in gold processing, ensuring that the pH remains at the correct level to mitigate risks associated with cyanide use.^[4]

^ ^a ^b Gail, Ernst; Gos, Stephen; Kulzer, Rupprecht; Lorösch, Jürgen; Rubo, Andreas; Sauer, Manfred; Kellens, Raf; Reddy, Jay; Steier, Norbert; Hasenpusch, Wolfgang (2011). "Cyano Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a08_159.pub3. ISBN 978-3-527-30385-4.
^ Etris, S. F. (2010). "Silver and Silver Alloys". Kirk-Othmer Encyclopedia of Chemical Technology. pp. 1–43. doi:10.1002/0471238961.1909122205201809.a01.pub3. ISBN 978-0471238966.
^ "Cyanide Management" (PDF). Australian Government.
^ Du Plessis, C. A.; Lambert, H.; Gärtner, R. S.; Ingram, K.; Slabbert, W.; Eksteen, J. J. (2021). "Lime use in gold processing – A review". Minerals Engineering. 174: 107231. Bibcode:2021MiEng.17407231D. doi:10.1016/j.mineng.2021.107231. S2CID 240128866.

[Ullmann-1] Gail, Ernst; Gos, Stephen; Kulzer, Rupprecht; Lorösch, Jürgen; Rubo, Andreas; Sauer, Manfred; Kellens, Raf; Reddy, Jay; Steier, Norbert; Hasenpusch, Wolfgang (2011). "Cyano Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a08_159.pub3. ISBN 978-3-527-30385-4.

[KO-2] Etris, S. F. (2010). "Silver and Silver Alloys". Kirk-Othmer Encyclopedia of Chemical Technology. pp. 1–43. doi:10.1002/0471238961.1909122205201809.a01.pub3. ISBN 978-0471238966.

[3] "Cyanide Management" (PDF). Australian Government.

[4] Du Plessis, C. A.; Lambert, H.; Gärtner, R. S.; Ingram, K.; Slabbert, W.; Eksteen, J. J. (2021). "Lime use in gold processing – A review". Minerals Engineering. 174: 107231. Bibcode:2021MiEng.17407231D. doi:10.1016/j.mineng.2021.107231. S2CID 240128866.

[1]

[2]

[3]

[4]