Leaching of galena by regenerated ferric ion (Fe3+) via electro-oxidation

Abstract

In this paper, a cycle of Fe3+ electro-oxidation regeneration and galena leaching with regenerated Fe3+ has been established. The whole investigation can be divided into three parts, respectively. Fe3+ regeneration, galena leaching with regenerated Fe3+, and the cycle of the two processes. In the first part, the relationship between the relevant parameters and Fe3+ regeneration was investigated, and it has been revealed that the increases of anodic current density, Cl− concentration and H+ concentration are beneficial to the Fe3+ regeneration. With 95.5% Fe3+ regeneration acquired, the appropriate regeneration conditions are determined as follows: Fe2+ concentration = 0.4 mol/L, Cl− concentration = 3 mol/L, H+ concentration = 4 mol/L, anodic current density = 1789 A/m2, initial Fe3+/ Fe2+ ratio = 0, electric quantity = 3 Ah, agitation speed = 400 rpm. With galena leaching by regenerated Fe3+, the effects of temperature, S/L ratio and leaching time have been investigated, and the leaching rate of 87.3% can be realized in just 12 minutes under the optimized conditions that temperature = 90 °C, S/L ratio = 40 g/L, agitation speed = 600 rpm. In the last part, the cycle of Fe3+ regeneration-galena leaching was tested, the comparison of the results from the two groups of experiments, in which the supply of H+ after Fe3+ regeneration was provided in one group, yet not in the other, indicates that the electro-oxidation regeneration of Fe3+ is at the expense of the consumption of H+ and the cycle could run stably with acquiring satisfying regeneration percentage and leaching rate if the H+ provided.