Promising hydrometallurgical technologies for processing zinc concentrates

In recent decades, more and more attention has been paid to the issue of processing substandard zinc concentrates using hydrometallurgical technologies that make it possible to convert the bulk of sulfide sulfur into an elemental form. The results of laboratory studies of two-stage countercurrent leaching of a sample of Russian zinc concentrate under atmospheric (temperature 95–100 oC) and autoclave (temperature 145–150 oC, oxygen pressure 0.7 MPa) conditions are presented. Based on the conducted research, two technological schemes have been formed and presented that make it possible to achieve high technological performance of processing zinc concentrate by hydrometallurgical methods (without roasting). With modern equipment, the basic parameters of each leaching stage were experimentally determined. Comparative characteristics of chemistry and indicators of the main operations of the two technologies are described. The possibility of achieving high rates of zinc extraction (>98%) in a productive solution is shown. During the experiments, it was found that the schemes make it possible to effectively purify the productive solution from iron and other hydrolyzable impurities (As and Sb) before cementation purification and electrolytic deposition of zinc. The main advantages and disadvantages of primary operations, as well as related subsequent operations of purifying the productive solution, are analyzed. A granulometric analysis of leaching residues was performed. The indicators of pulp dehydration after two stages of atmospheric and autoclave leaching are presented with a brief justification of the possible causes of the sedimentation characteristics of the obtained pulps.