Sianidasi process consists of two important stages, namely the process of dissolving and the separation of gold from
solution. Solvents commonly used in the process cyanidasi is NaCN, KCN, Ca (CN) 2, or a mixture
three. The most common solvent used is NaCN, being able to dissolve gold better
from other solvents. Generally, dissolving the reaction Au and Ag are as follows:
8CN-4Au + + O2 + 2 H2O = 4Au (CN) 2 – + 4OH -
8CN-4Ag + + O2 + 2 H2O = 4Ag (CN) 2 – + 4OH -
In the second stage of the separation of gold metal from solution is done by precipitation using
Zn powder (Zinc precipitation). The reaction is as follows:
2 Zn + 2 NaAu (CN) 2 + 4 NaCN +2 H2O = 2 Au + 2 NaOH + 2 Na2Zn (CN) 4 + H2
2 Zn + 2 NaAg (CN) 2 + 4 NaCN +2 H2O = 2 Ag + 2 NaOH + 2 Na2Zn (CN) 4 + H2
Tags: gold