6. Chemistry of silver dissolution by complexation

Cyanide has long been known as a powerful leaching agent for gold and silver, as it produces highly stable cyano-complexes. Cyanide is very effective at leaching gold and silver ores, but certain types of ore are considered refractory (carbonaceous, pyritic, arsenous, manganiferous, cuproferous ores). This has led to a search for other leachants capable of treating these ores or concentrates. The behaviour of silver (like that of gold) can be understood as an electrochemical dissolution that can be interpreted from potential-pH diagrams (or Eh – pH), not only to explain cyanidation but also the dissolution by other leachants.