Dissolving gold and silver in a dilute cyanide solution — the standard extraction chemistry for over a century.
A process that uses cyanide solution to dissolve gold from ore. The gold is then recovered from solution through adsorption on activated carbon or zinc precipitation. This is the most common method for gold extraction worldwide.
Practically every gold project assumes it, so the interesting question is whether the ore responds. Free-milling ore leaches readily; refractory ore does not, and the difference is millions in extra capital.
Cyanide use drives much of a project's permitting and community risk, and is banned outright in some jurisdictions. That is a jurisdictional question as much as a technical one.