Аннотация
The article examines the conditions of selective flotation of galena from copper–sulfide ores. Selective flotation of galena occurs when elemental sulfur, which is hydrophobic, forms on its surface, while oxygen-containing compounds on the surface of copper sulfides exhibit increased wettability. To identify compositional differences in the surface compounds of galena and copper sulfides (chalcocite, bornite, chalcopyrite), the effects of two stage-specific reagents were studied: sodium thiosulfate (Na2S2O3×5H2O) and potassium ferricyanide K3[Fe(CN)6]. The flotation of the valuable minerals is carried out without collectors, based on the natural floatability of galena. On the chalcocite surface, the action mechanism of sodium thiosulfate consists in increasing hydrophilic oxygen-containing zones as a result of the formation of thiosulfate copper complexes. When interacting with the galena surface, sodium thiosulfate slows the oxidation of elemental sulfur and reduces sulfur within the surface layer, thereby enhancing its hydrophobization. IR spectroscopy results revealed the presence of elemental sulfur on the galena surface and of oxygen-containing compounds on copper minerals; differential thermal analysis determined the degree of mineral wettability. Mineralogical analysis established that sodium thiosulfate suppresses (inhibits) the flotation of chalcocite and bornite. To determine the degree of surface hydration of sulfide minerals, differential thermal analysis in combination with thermogravimetric analysis was employed. The differential thermal analysis curves exhibited endothermic peaks caused by the desorption of physically bound water from the mineral surface upon heating. The degree of surface hydration was characterized by the onset temperature of the endothermic effect (t0С), the proportion of adsorbed moisture relative to the total (n), and the desorption heat QD. A decrease in the onset temperature of the endothermic effect indicates an increase in surface hydrophobicity, since at lower temperatures the adsorbed moisture begins to evaporate, and consequently, the hydrogen bonds are weakened.