KINETICS OF SPHALERITE LEACHING IN ACIDIC FERRIC CHLORIDE SOLUTIONS

The kinetics of leaching of sphalerite ore in ferric chloride-hydrochloric acid solutions was investigated. Over the temperature interval 70 to 90(degree)C the dissolution of zinc value occured according to a linear rate law, and with an associated apparent activation energy of about 31.2 kJ.mol^-1. The leaching rate was affected by agitation and this fact together with other hydrodynamic calculations indicated that the reaction was mass transfer controlled. At a fixed concentration of hydrochloric acid. dissolution of zinc increased with increasing concentration of ferric chloride. However, the effect was less pronounced at ferric chloride concentrations above 1.0 M. Similar trends of results were also observed for the dissolution rates measured at different hydrochloric acid concentrations but at a fixed ferric chloride concentration. The accumulation of the ferrous chloride reaction product in the reactor severely retarded the leaching reaction.