Regular Article

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

¹ College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China
² Hunan Provincial Key Laboratory of Efficient and Clean Utilization of Manganese Resources, Central South University, Changsha 410083, Hunan, PR China

^* e-mail: zfcaocsu@163.com; zhongh@csu.edu.cn

Received: 13 March 2018
Accepted: 3 October 2018

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.