Simultaneous acid Co and Cu leaching from oxidised and sulfide mixture ores: optimisation and kinetic study

The current investigation studied factors affecting the leaching of Co and Cu from an oxidised and sulfide ores mixture. The kinetic study was performed to determine mechanisms limiting leaching steps after optimising the leaching parameters using response surface methodology (RSM). The optimisation was done using Statistica 12.5 software. After characterisation of the as-received sample using X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), the effects of controllable variables such as temperature, stirring speed, solid-to-liquid ratio, and oxide-to-sulfide ratio were investigated in the presence of H₂SO₄. At the same time, Cu and Co recoveries were the leaching responses. After investigation, results revealed that 83% and 97% of Cu and Co were respectively recovered when leaching the mixture oxide-sulfide sample (80/20 wt%) with 72 g/L H₂SO₄, 100 g/L solid–liquid ratio at 40°C while stirring at 650 rpm for 110 min. Kinetics results indicated that using the progressive conversion model from 0 to 5 min led to a chemical-controlled mechanism. On the other hand, the shrinking core model was applied for 5–140 min. The overall mechanism based on the activation energy values indicates that the dissolutions of both metals were diffusion-controlled.