Atmospheric leaching of chalcopyrite in the presence of some polar organic reagents: A comparative study and optimization

Chalcopyrite, CuFeS2 is the most important mineral of copper, but it is a refractory mineral and does not easily dissolve in various leaching solutions. In the present work, sulfuric acid solution containing hydrogen peroxide as the oxidant was used for leaching of chalcopyrite at ambient pressure and temperatures up to 65 degrees C. Recent investigations have shown that the presence of some polar organic solvents in the leach liquor increases the efficiency of copper leaching from chalcopyrite, probably due to stabilization of hydrogen peroxide. A comparative study on the effect of five polar organic reagents: acetone, ethanol, ethylene glycol, isopropanol and methanol at exactly the same conditions was done for the first time. It was found that the isopropanol is significantly more effective than others and ethanol was found to be the weakest. The leaching efficiency surprisingly increased from below 50% to over 80% by adding 1 mol/L isopropanol into the leaching solution. The optimized condition for leaching was found to be as: 1.5 mol/L H2SO4, 2 mol/L H2O2, 2 mol/L isopropanol and temperature of 65 degrees C with dissolved copper of 85% after 120 min. X-ray diffraction and scanning electron microscopy proved the formation of elemental sulfur while no evidence of surface passivation of chalcopyrite was found.