Abstract

The kinetics of leaching of enargite (Cu3AsS4) were studied in NaOCl solution for ranges of 20–60 °C, 0.07–0.47 M ClO− and 0.003–0.03 M OH−. The reaction is topochemical in nature with enargite particles converted to crystalline CuO. Complete conversion occurs according to:Cu3AsS4+11OH−+35/2ClO−→3CuO+AsO43−+4SO42−+11/2H2O+35/2Cl− The very fast reaction rates were limited by the chemical reaction; the kinetic equation was found to be:1−(1−X)1/3=3.57×102exp(−58400/RT)r0[ClO−]1/2[OH−]1/2t A proposed electrochemical mechanism and a surface study by XPS was discussed. This leaching process could be used to remove arsenic from copper concentrates containing enargite.