Application of deep eutectic solvents for dissolution of sulphide ores: Review

Deep eutectic solvents are a new class of biodegradable, inexpensive and environmentally friendly solvents. These solvents are created by combining quaternary ammonium salts, which can be converted into liquids at temperatures lower than their melting points. Recently, researchers in various fields have shown increased interest in deep eutectic solvents as alternatives for dissolving oxides in metal extraction processes. Electrochemical studies have demonstrated successful dissolution of some oxide minerals in these solvents, while results have been less consistent for others. This review focuses on the dissolution of sulphide ores in deep eutectic solvents. Arsenopyrite and pyrite exhibit similar thermodynamic properties, as well as comparable stability and solubility in aqueous solutions. Pyrite has been successfully dissolved using choline chloride-based deep eutectic solvents; however, challenges have been noted in dissolving arsenopyrite with these solvents. The review also proposes that successful dissolution of arsenopyrite in deep eutectic solvents can occur at atmospheric pressure and relatively low temperatures through direct leaching.