Abstract
This research study was conducted to evaluate the dissolution and electrochemical behaviour of low grade Cu-Co oxide ore (0.4% Cu; 3% Co) in ammonium chloride media (NH4Cl) by means of polarization and potentiometric measurements. Polarization measurements were carried out to evaluate the electrochemical behaviour as well as the leaching and re-passivation behaviour of the ores at pH of 9.5, 9.6, 9.7 and 9.8 in NH4Cl solution. In all the pH tested, the potential changed from negative to electropositive values suggesting formation of passive film on the surface of the ore which lowered the dissolution rates. Stable behaviours as were as high dissolution rate were observed at pH of 9.5. Potentiometric measurements were carried out at constant current and varying potential to study the reactivity of Cu-Co oxide ores in 0.25M, 0.5M and 1M of NH4Cl solution. In this test the dissolution rates increased with increasing concentration and the pH decreased with increasing concentration and time suggesting production of acid as oxidation reaction takes place, the ranges of pH are depicted in the Pourbaix diagrams. Stable behaviours were observed in 1M of solution. All observations made in these measurements are confirmed by AAS, XRF, SEM and XRD analysis.