Electrochemical Pretreatment of Chrysocolla for Enhanced Sulfidization and Flotation: Mechanism and Process Optimization.

The flotation of oxidized copper minerals is limited by poor surface reactivity and the insufficient effectiveness of conventional sulfidization. This study investigated 50 Hz alternating current electrochemical pretreatment to enhance the sulfidization and flotation of chrysocolla and a natural oxidized copper ore. Operating parameters, including current density, treatment time, pulp pH, and sodium sulfide dosage, were optimized using a design of experiments approach. Phase transformations were characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy and X-ray diffraction. Pretreatment with 50 Hz alternating current promoted the surface formation of tenorite (CuO), which was subsequently transformed into covellite (CuS) during sulfidization, providing favorable conditions for subsequent flotation. The optimum conditions for chrysocolla were a current density of 100 A m-2, a pretreatment time of 0.5 min, pH 8, a sodium sulfide dosage of 25% of the stoichiometric requirement, and a sulfidization time of 2.5 min. Validation tests on natural oxidized copper ore showed that alternating current pretreatment increased copper recovery from 29.16% to 79.63% and concentrate grade from 12.84 to 25.50 wt.% compared with conventional sulfidization. These findings demonstrate that alternating current electrochemical pretreatment effectively modifies oxidized copper mineral surfaces and enhances their subsequent sulfidization and flotation, providing a promising approach for the beneficiation of refractory oxidized copper ores.