Chalcopyrite leaching in sulfate–chloride media at ambient pressure

In this article, experimental results on the leaching of a chalcopyrite concentrate with oxygen at ambient pressure in H2SO4–NaCl solutions are discussed taking into account the evolution of the solution redox potential and the concentration of ferric ions during leaching. The results indicate that leaching of chalcopyrite concentrate with particle size 12.3 μm in sulfate–chloride solutions was rapid. Over 90% copper was dissolved in 180 min at 100 °C. The results also showed that 17.7 g/l (0.5 M) of chloride ions in the leaching solution affected significantly the leaching rate as compared to leaching without chloride. The addition of 3 g/l of ferric ions to the leaching system produced a large increase in the solution potential which in turn affected negatively the leaching rate of chalcopyrite. The leaching of chalcopyrite in H2SO4–NaCl–O2 media depends largely on the temperature, and the linear kinetics model 1−(1−X)1/3 = kt represents the copper dissolution well. An activation energy value of 91.2 kJ/mol was determined for the temperature range of 80 to 100 °C.

► Chalcopyrite leaching in H2SO4-NaCl-O2 media is faster than in pure sulfate media.
► High solution redox potentials affect the chalcopyrite leaching negatively.
► The dissolution of chalcopyrite in H2SO4-NaCl-O2 occurs with linear kinetics.