Rapid atmospheric leaching of enargite in acidic ferric sulfate media

• Fast enargite dissolution is achieved under the presence of pyrite in acidic media at atmospheric conditions.
• Elemental sulfur is the only solid residue from enargite leaching. Pyrite did not show clear evidence of dissolution.
• Dissolution of enargite is mainly affected by pyrite content, temperature and sensitive to solution potential.
• Iron and sulfuric acid concentrations had negligible effects.

A new method is presented for the rapid dissolution of enargite enhanced by the addition of pyrite as catalyst in acidic ferric sulfate media. At atmospheric conditions the effects of the ratio of pyrite (FeS2) to enargite (Cu3AsS4), temperature, solution potential, iron concentration, sulfuric acid concentration, particle size, and pulp density were evaluated. The best conditions were found to be at 80 °C with a pyrite to enargite ratio (Py:En) of 4, which gave complete copper extraction within 24 hours. The dissolution rate appears to be insensitive to changes in iron and acid concentrations. Elemental sulfur formed a porous layer on the surface of enargite particles, while pyrite surfaces remained clean. Arsenic presented the same dissolution rate as copper and all of the arsenic reported to solution, predominantly in the form of As(III).