Editing Gold cyanidation (section)

{{Short description|Technique for extracting gold from low-grade ore}}

'''Gold cyanidation''' (also known as the '''cyanide process''' or the '''MacArthur–Forrest process''') is a [[hydrometallurgy|hydrometallurgical]] technique for extracting [[gold]] from low-grade [[ore]] through conversion to a water-soluble [[coordination complex]]. It is the most commonly used [[leaching (chemistry)|leaching]] process for [[gold extraction]].<ref name=Ullmann>{{cite book|doi=10.1002/14356007.a08_159.pub3 |chapter=Cyano Compounds, Inorganic |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2011 |last1=Gail |first1=Ernst |last2=Gos |first2=Stephen |last3=Kulzer |first3=Rupprecht |last4=Lorösch |first4=Jürgen |last5=Rubo |first5=Andreas |last6=Sauer |first6=Manfred |last7=Kellens |first7=Raf |last8=Reddy |first8=Jay |last9=Steier |first9=Norbert |last10=Hasenpusch |first10=Wolfgang |isbn=978-3-527-30385-4 }}</ref> Cyanidation is also widely used in [[silver]] extraction, usually after [[froth flotation]].<ref name=KO>{{cite book |chapter=Silver and Silver Alloys |title=Kirk-Othmer Encyclopedia of Chemical Technology |year=2010 |last1=Etris |first1=S. F. |pages=1–43 |isbn=978-0471238966 |doi=10.1002/0471238961.1909122205201809.a01.pub3}}</ref>

Production of [[reagent]]s 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. <ref name=Ullmann/> 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.<ref>{{Cite web |title=Cyanide Management |url=https://www.industry.gov.au/sites/default/files/2019-04/lpsdp-cyanide-management-handbook-english.pdf |publisher=Australian Government}}</ref> One critical factor in its safe use is maintaining an alkaline pH level above 10.5, which is typically controlled using [[lime (material)|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.<ref>{{cite journal |title=Lime use in gold processing – A review |year=2021 |last1=Du Plessis |first1=C. A. |last2=Lambert |first2=H. |last3=Gärtner |first3=R. S. |last4=Ingram |first4=K. |last5=Slabbert |first5=W. |last6=Eksteen |first6=J. J. |journal=Minerals Engineering |volume=174 |page=107231 |bibcode=2021MiEng.17407231D |s2cid=240128866 |doi=10.1016/j.mineng.2021.107231 |doi-access=free}}</ref>