Give the chemical reactions involved in the leaching of gold. What is the role of in this process ?
Chemical reactions involved in the leaching of gold are-
4 Au + 8CN- + 2H2O + O2 4[Au(CN)2]- + 4OH
2 [Au(CN)2]- + Zn [Zn(CN)4] 2- + 2 Au
Zn acts as a reducing agent.