Kinetics of the pressure leaching of enargite in FeSO4–H2SO4–O2 media

• The pressure leaching of enargite with FeSO4–H2SO4–O2 was studied experimentally.
• Ferric ion in solution is the main oxidant of enargite in this media.
• Enargite dissolves with linear kinetics and the surface reaction controls the rate.

The pressure leaching of enargite in FeSO4–H2SO4–O2 media was studied with the aim to determine the role of the ferrous ions on the rate of arsenic dissolution in the temperature range of 140–200 °C. Thus, the effect of ferrous sulfate addition into the leaching of enargite was determined under partial pressure of oxygen in the range of 207–1379 kPa. The results showed that the addition of ferrous ions greatly enhanced the leaching rate of enargite, which confirmed that the ferric ion generated in the solution is the major oxidant of enargite while the role of the oxygen in this system was essentially to regenerate the ferric ion. It was also determined that the cupric ions from the enargite dissolution catalyzed the oxidation of ferrous ions to ferric. The kinetics data of the enargite dissolution in this system was analyzed by using the shrinking particle model for monosized particles considering a surface chemical reaction control. The apparent activation energy determined with this model was 111.8 kJ/mol for the temperature range 140 to 200 °C.

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