Synergistic depression of copper-activated pyrite by Fe2+/baicalin system: a novel strategy for selective Zn-S flotation

Organic depressants often exhibit low selectivity at high dosages, and introduce risks of concentrate dewatering. The combined depressants composed of inorganic and organic substances can significantly reduce reliance on organic depressant dosage, providing a promising solution to this challenge. In order to achieve highly efficient separation of sphalerite and pyrite in the CuSO 4 -butyl xanthate (PBX) flotation system, the combined depressant Fe 2+ / baicalin (BCL) was innovatively employed to inhibit copper-activated pyrite. The flotation tests indicate that compared with the single depressant BCL, the combined depressant Fe 2+ /BCL demonstrates superior selective inhibitory effects on copper-activated pyrite. For artificially mixed ores, a zinc concentrate is obtained with a zinc grade of 62.33 % and a zinc recovery of 93.86 % when the combined depressant of 10 mg/L Fe 2+ and 5 mg/L BCL are used, and the separation efficiency is significantly improved from 40.66 to 79.69 %. Adsorption characteristic studies indicated that BCL exhibits stronger affinity for copper-activated pyrite than for sphalerite. The introduced Fe 2+ provide additional active sites, thereby enhancing the depression effect on copper-activated pyrite. Following Fe 2+ /BCL modification, the adsorption of PBX on copper-activated pyrite was hindered, while having no substantial impact of that on sphalerite, which is also confirmed by molecular dynamics simulations. Therefore, the combined depressant Fe 2+ /BCL markedly widened the hydrophobicity difference between sphalerite and pyrite, creating the potential for their effective separation.