Abstract
Chalcopyrite (CuFeS₂) is the most abundant copper sulfide mineral, yet its dissolution remains kinetically hindered under many leaching conditions. While acidic systems have been widely studied, oxidative dissolution of chalcopyrite in alkaline media is comparatively less understood, despite its relevance to emerging environmentally benign hydrometallurgical processes. In this work, the oxidative dissolution behavior of chalcopyrite in alkaline solutions was investigated using a combination of electrochemical techniques, including potentiodynamic polarization and electrochemical impedance spectroscopy, complemented by solution chemistry analysis and surface characterization using scanning electron microscope and raman sepctroscopy.
The activation energy was calculated for chalcopryite at pH 10 using electrochemical method as varioud potentials. It was found that between 100 to 750 mV vs Ag/AgCl, activation energy ranges between 24.5 to 45.4 kJ/mol, indicating the process being electrochemically controlled rather than diffusion-controlled.
It was also found that with while using sodium hypochlorite as potential controller, the oxidation product resembles certain features found in pyrite, covellite and cuprite. This oxidation product layer was found to be highly acid soluble and provide Fe: Cu ratio of 1:1.
In general, this work reveals important mechanism involved in the oxidation of chalcopyrite in alkaline media which potentially leads to new process of metal's extraction from tailings or other minewaste where acid consumption is an issue.