Extraction of gold and silver involves leaching with ${\text{CN}}^{-}$ ion. Silver is later recovered by:

In the Mac-Arthur Forrest cyanide process, silver is leached to form a soluble complex $[{\text{Ag(CN)}}_2{]}^{-}$. Silver is then recovered from this complex by adding zinc powder, which acts as a reducing agent and displaces the silver.
$$2[{\text{Ag(CN)}}_2{]}^{-}+\text{Zn}\to [{\text{Zn(CN)}}_4{]}^{2-}+2\text{Ag}\downarrow$$