How is Ag or Au obtained by leaching from the respective ores?

Explanation

Ag and Au are leached with a dilute solution of NaCN (or) KCN in presence of `O_(2)`(air).from the leached solution the metal is obtained through displacement by Zinc.
`4M_((s))+8CN_((aq))^(-)+2H_(2)O_((aq))+O_(2_((g)))rarr4[M(CN)_(2)]_((aq))^(-)+4OH_(aq)^(-)`
`2[M(CN)_(2)]_(aq)^(-)+Zn_((s))rarr[Zn(CN)_(4)]_((aq))^(2-)+2M_((s))`