Abstract
The kinetics of leaching galena with ferric chloride and ferric nitrate have been examined as a function of ferric concentration, salt concentration, temperature, and particle size. Diffusivity of ferric complex ions was also established as a function of ferric chloride concentration and temperature. In the presence of 3m nacl, leaching rate is controlled by product layer diffusion when ferric chloride is added as oxidant. With nacl concentrations less than 3 mol/l, rate decreases with decreased nacl concentration, and thus, rate is apparently not controlled by product layer diffusion. It is suggested that rate is controlled by lead chloride solubility at the reaction interface under these conditions. When ferric nitrate is added as oxidant, leaching rate is limited by chemical reaction control. An electrochemical model is presented. Activation energies are 8.1 and 11.3 Kcal/mol in the ferric chloride and ferric nitrate systems, respectively.
