Electrochemical study of enargite within the mixed potential zone attained with different oxidizing reagents in an alkaline medium

•With each oxidizing reagent used, enargite attains higher potentials than chalcopyrite.•The mixed potential on enargite follows the order Ca(ClO)2 > KMnO4 > NaClO > H2O2.•Higher hydrophilicity on enargite is produced when Ca(ClO)2 and KMnO4 are used.•NaClO presents advantages for surficial conditioning by potential control in flotation. A better efficiency for the selective flotation of copper sulfides containing enargite (Cu3AsS4) can be achieved through potential control. It is proposed that oxidizing reagents as surface modifiers could selectively change the flotation behavior of the minerals involved in the concentration process. Hence, it is essential to evaluate the oxidation response of enargite produced after conditioning its surface with different oxidizing reagents. For this purpose, enargite surface oxidation was studied by means of electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The oxidation of this mineral was evaluated either by imposing a potential within the mixed potential window achieved with different oxidizing reagents (hydrogen peroxide, sodium and calcium hypochlorite, and potassium permanganate) or by previous conditioning of the enargite surface with them. The mixed potential results show that enargite and chalcopyrite achieve distinct values using the same oxidizing reagent under the same experimental conditions and therefore different oxidation of the surfaces of the two minerals. The order in potential observed for enargite was Ca(ClO)2>KMnO4>NaClO>H2O2 and for chalcopyrite KMnO4>NaClO>Ca(ClO)2>H2O2. Additionally, the electrochemical results show there are different surface products depending on the oxidizing reagent used. Thus, either potential and/or additional chemical processes, such as adsorption of such products, can modify the surface and establish the hydrophobic or hydrophilic character of the surface. The results show that the performance of NaClO as an oxidizing reagent makes it adequate for the control of potential in the flotation process, particularly because it does not generate oxidizing products that could interfere with this process.