Abstract
The processing of oxidized lead–zinc ores is complicated by the hydrophilic surface of valuable minerals, fine dissemination, and the significant presence of silicate and slime components, which reduce flotation selectivity and concentrate quality. This study aimed to improve the quality of a lead–zinc concentrate obtained from oxidized ore of the Koshkuduk deposit by optimizing the dosage of sodium silicate (Na₂SiO₃) during flotation after preliminary sulfidization with calcium polysulfide. Laboratory flotation tests were carried out using sodium silicate dosages ranging from 0 to 500 g/t. The process performance was evaluated based on concentrate yield, Pb, Zn, and Ag grades, recoveries, the Hancock–Luyken separation efficiency criterion, and an additionalseparation criterion. Without sodium silicate, the concentrate yield was 7.20 %, with Pb, Zn, and Ag grades of 3.78 %, 3.15 %, and 50.03 g/t, respectively. The optimal Na₂SiO₃ dosage was 170 g/t, at which the concentrate yield decreased to 3.62 %, while Pb, Zn, and Ag grades increased to 8.58 %, 6.44 %, and 100.46 g/t, respectively. The corresponding recoveries were 53.56 % Pb, 41.64 % Zn, and 66.12 % Ag. Further increasing the Na₂SiO₃ dosage to 200–500 g/t did not improve flotation performance. The results demon-strate that sodium silicate effectively improves concentrate quality by depressing silicate and slime minerals in oxidized lead–zinc ore flotation.