An integrated approach to evaluate the leaching behaviour of silver from sulfide concentrates

The leaching rates of two different mineral concentrates with the same silver content were investigated by cyanide leaching with silver phases identified by scanning electron microscopy (SEM) and electrochemical analysis. The mineralogical characterization (SEM) of the concentrates showed that each contained the silver in different phases. After leaching, the disappearance of only one of the phases in each concentrate was detected. The remaining silver was contained in phases that are refractory to cyanidation. Simultaneously, an electrochemical method for the detection of the different leachable and refractory silver phases in concentrates and leach residues was developed. Cyclic voltammetry was employed with the concentrate-carbon paste electrodes (concentrate-CPE) in order to detect the oxidation of the different phases of silver contained in the mineral concentrates. The extreme sensitivity of this method allowed the rapid and reliable detection of small quantities of silver, as well as the evaluation of its refractory nature.