Overcoming alkaline flotation dependence: Mechanistic insights into selective adsorption of 1-dodecyl-3-methylimidazolium bromide in the reverse flotation of smithsonite and quartz

The depletion of high-grade sphalerite has directed attention to smithsonite as a strategic substitute for sustaining zinc supply. However, its close association with quartz complicates selective separation, while conventional direct flotation requires moderately to strongly alkaline pulps, causing equipment corrosion, excessive reagent consumption, and unstable concentrate quality that hinder large-scale use. To address this issue, 1-dodecyl-3-methylimidazolium bromide (DMB) was employed as a new collector, providing an alternative chemical environment and enabling, for the first time, an efficient reverse-flotation route for separating smithsonite from quartz. Micro-flotation tests showed that at pH = 7.0 with only 30 mg/L DMB, the concentrate reached 47.05 % Zn with 92.78 % Zn recovery and 95.03 % desilication efficiency, demonstrating both high selectivity and low reagent consumption. Electrokinetic, spectroscopic, and microscopic analyses revealed that DMB adsorption on quartz is governed by electrostatic attraction and hydrogen bonding, increasing surface potential, hydrophobicity, and roughness, whereas electrostatic repulsion limited adsorption on smithsonite, preserving its hydrophilicity. This study establishes a simplified flotation route independent of strong alkalinity, showing high adaptability to high-silica, low-grade smithsonite ores and offering valuable theoretical insight and a broader framework for advancing efficient recovery and utilization of oxidized zinc resources.