KINETICS AND MECHANISMS OF THE LEACHING OF LOW FE SPHALERITE

Abstract

The surface speciation and leaching kinetics of 38- to 75-μm 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 straight-line 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.