Kinetics and mechanisms of the leaching of low Fe sphalerite, Pages 823-830

The surface speciation and leaching kinetics of 38- to 75-(mu)m sphalerite (0.45 wt.% Fe) particles reacted in O2 purged perchloric acid (at pH 1.0) at 25, 40, 60, and 85 °C over a leach period of 144 h were investigated. In all cases, an initial rapid leach rate is observed followed by a slower leach rate. These two leach regimes can each be adequately modeled using straightline interpolation, and thus two activation energies (Ea) have been derived. Ea for the fast and slow Zn dissolution rates were 33 ± 4 kJ mol-1 and 34 ± 4 kJ mol-1 respectively, suggesting the same rate-determining step.