Аннотация
Monosodium glutamate (MSG) was evaluated for the first time as a chelating agent for selective alkaline leaching of copper from porphyry copper flotation tailings containing 0.33% Cu. The tailings are composed predominantly of quartz, feldspar, chlorite, and calcite, with chalcopyrite occurring as microinclusions enclosed within the silicate gangue matrix. The effects of MSG concentration (0.25-1.0 M), oxidant type (H2O2 and KMnO4), and temperature (25-60 °C) on copper extraction and selectivity were investigated at pH 9.5. KMnO4 was found to be a more effective oxidant than H2O2 under alkaline conditions, attributed to its greater stability and higher redox potential at this pH. Under optimal conditions (0.75 M MSG, 0.03 M KMnO4, 60 °C, 24 h), copper extraction reached 78.6% while iron co-dissolution was limited to 0.85%, yielding a Cu/Fe separation factor of 92. Kinetic analysis using the shrinking core model indicated mixed control with an apparent activation energy of 24.6 kJ·mol. XRD analysis of the leaching residue showed a significant decrease in chalcopyrite reflections, while pyrite peaks remained essentially unchanged. SEM-BSD imaging revealed intact cubic pyrite crystals in the residue with no evidence of surface corrosion, providing direct morphological confirmation of the process selectivity.