GOLDddd....

Assuming that deviation from standard conditions is unimportant in this case and that all these redox reactions go essentially to completion. Given:
[Zn(CN)4]2- + 2 e- ------- Zn + 4 CN- E = -1.26 V
[Au(CN)2]- + e- -------- Au + 2CN- E = -0.60V
[Ag(CN)2]- + e- --------- Ag + 2 CN- E = -0.31V
What would be the concentrations of [Ag(CN)2]- after the addition of Zn in it?

What concentration of cyanide ion is required to keep 99 mol % of the gold in solution in the form of the cyanide complex?
(Kf of gold complex is 4 * 10^28)

There have been several efforts to develop alternative gold extraction processes, which would replace the present one. The reason for this is

1.NaCN solution corrodes mining machinery.
2.gold obtained by this process is impure.
3.silver is precipitated faster than gold.
4.NaCN escapes into ground water and releases HCN.