Review of Enargite Flotation—Part I: Surface Characterization and Advances in Selective Flotation

Enargite (Cu3AsS4), a copper–arsenic sulfosalt, represents a critical challenge in copper mineral processing due to its high arsenic content, which poses significant environmental, metallurgical, and economic issues. Its flotation behavior closely resembles that of other copper sulfides such as chalcopyrite and chalcocite, complicating selective separation at early beneficiation stages. This review presents a comprehensive examination of enargite’s surface chemistry and electrochemical behavior, focusing on the influence of oxidation, pH, and pulp potential on surface reactivity, charge distribution (zeta potential), and hydrophobicity. Detailed insights into the formation of surface oxidation layers, passivation mechanisms, and contact angle variations are provided to elucidate collector-mineral interactions. Advances in selective flotation techniques are also discussed, including the use of depressant reagents, controlled redox environments, and reagent conditioning strategies. Special attention is given to flotation in seawater, where ionic strength and multivalent ions significantly influence mineral-reagent interactions and flotation outcomes. Galvanic interactions between enargite and other sulfide minerals are identified as critical factors affecting floatability and selectivity. The review consolidates findings from recent experimental and electrochemical studies, highlighting promising approaches to enhance enargite rejection and copper concentrate purity. It concludes with perspectives on future research aimed at optimizing flotation processes and developing sustainable solutions for processing arsenic-bearing copper ores.