Electrochemical dissolution of roasted gold ore in cyanide solutions

This study investigates the electrochemical dissolution behavior of roasted gold ore (RGO) in cyanide solutions, aiming to identify optimal leaching conditions and corrosion rates. Utilizing free corrosion tests and electrochemical noise measurements, it was found that pure gold exhibits more active behavior compared to RGO, with an initial increase in corrosion rate for gold that plateaus for RGO after 10 hours. Scanning reference electrode techniques indicated higher electromotive forces for pure gold. The optimal leaching parameters for RGO were identified as a sodium cyanide concentration of 0.04 M, a pH of 10-10.5, and an agitation speed of 250 rpm. Detailed analysis revealed that the cathodic Tafel slope is the primary factor influencing corrosion rates during cyanidation, contradicting traditional models that treat anodic and cathodic sites separately. Potentiodynamic scanning without prior cathodic cleaning yielded consistent results for both electrode types. Scanning electron microscopy (SEM) analysis suggested that iron-oxide products play a significant role in the passivation of the gold surface. The findings enhance the understanding of gold dissolution mechanisms in cyanide solutions and offer insights for the optimization of gold recovery processes.