Electrochemical behavior of gold dissolution with a novel eco-friendly synthetic gold lixiviant

Abstract

Using environmentally friendly cyanide-free lixiviants to extract gold is of great significance with the rising requirement for environmental protection worldwide. A novel eco-friendly synthetic gold lixiviant (NESGL) that shows great potential to replace cyanide has been reported recently. In this paper, the electrochemical behavior of gold dissolution in the NESGL solution is investigated for the first time. Results suggest that gold occurs active dissolution in the potential of −300 to 600 mV where the coulombic efficiency of gold dissolution is >85.8 % but undergoes substantial reduction in oxidative dissolution at potentials higher than 600 mV due to the much-enhanced oxidation of NESGL. In contrast with cyanidation, no passivation on gold surface occurs in the NESGL solution achieving continuous leaching of gold with time. The change in pH significantly influences the NESGL dissolution of gold, and the optimal pH value appears to be 11. At the potential of 150–300 mV, the NESGL leaching of gold has an activation energy of 6.9–7.7 kJ·mol−1, indicating a diffusion-controlled leaching process.