The effect of gold on anode passivation and high current density operation under simulated silver electrorefining conditions
By Arif Aji and Sunara Purwadaria and Jari Aromaa and Benjamin P. Wilson and Olof Fors
Published in Hydrometallurgy
2016
Abstract
In the silver electrorefining process, the presence of gold as an impurity in anodes can affect process performance. In the present investigation, the effect of gold on anode passivation and the kinetics of dissolution at high current density were studied. Experiments were conducted using artificial silver anodes with gold contents of 2%, 5%, 10% and 20% (w/w) and acidic nitrate electrolytes containing 40 g/dm3 and 60 g/dm3 of Ag+. Results obtained from potentiodynamic measurements showed that in order to have higher current densities than 50 mA/cm2 and higher energy efficient operation, the gold content in anode should be limited to ? 10% with 60 g/dm3 of Ag+ electrolyte. In contrast, the same current density operation for 40 g/dm3 electrolyte will be applicable for anodes with ? 3.2% gold content with high energy inefficiency.