Accelerating copper leaching from a complex ore containing atacamite: optimisation and kinetic studies

Owing to the scarcity of atacamite, it has not been the subject of much research. In this study, the leaching of atacamite Cu2Cl(OH)(3) using H2SO4 was studied to evaluate the effect of different parameters such as temperature, time, acid concentration, agitation rate and pulp density to achieve the highest percentage of copper dissolution. The results showed that the copper dissolution from the atacamite ore can be increased from 50% to 75% using 1.5 M H2SO4 at the temperature of 80 degrees C within 50 min, when the % solids and stirring speed were fixed at 20% and 300 rev min(-1), respectively. The characterisation of leaching residue by XRD and SEM-EDS also confirmed the results. Moreover, a kinetics study based on the shrinking core model (SCM) showed that the leaching of atacamite at the initial phase (< 2 min) can be explained in terms of a diffusion model while a mixed diffusion/chemical reaction model controls the rate at the second step where other copper-bearing minerals leach.