In Situ Characterization of the Locked Particle Behavior of Sulfide Minerals Using Non-Destructive Electrochemical Measurements

Abstract

The flotation of sulfide minerals mostly depends on electrochemical reactions occurring on the mineral surfaces. Understanding the interaction mechanisms in the pulp is crucial for explaining the effects of different flotation chemicals on flotation performance. For this purpose, electrochemical techniques are used in the flotation of sulfide minerals by utilizing the semiconductor properties of these minerals. In this study, three non-destructive electrochemical measurements - open circuit potential (OCP), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) - were used to assess the electrochemical reactivity of the locked and liberated sulfide particles. Various combinations of mineral electrodes - Galena/Pyrite (0.52 cm2), Galena/Sphalerite (0.35 cm2), pure Galena (0.20 cm2), pure Sphalerite (0.80 cm2) and pure Pyrite (0.18 cm2) - were tested. A three-electrode electrochemical cell configuration was set up to investigate the electrochemical responses of the prepared electrodes. The changes in the surface chemistry of the mineral electrodes, in the presence (1×10-4 M NaEX) and absence of a collector were compared in detail. During the process, charge transitions occurred between the minerals in the locked particle mineral electrode due to galvanic interactions regardless of the surface area. Thus, the flotation behavior of the minerals changed by reducing and oxidizing each other. The present study suggests that the electrochemical methods may be an alternative technique to the conventional batch scale flotation tests as they can easily monitor the effect of any flotation reagents in the system causing possible reactions that may occur on sulfide mineral surfaces.