Precise regulation of Smithsonite–Quartz interfacial behavior by a low-dosage piperidinium collector in a reverse flotation system

Background The efficient separation of smithsonite from quartz remains a key bottleneck in the valorization of oxidized zinc ores. Conventional sulfidization flotation suffers from high reagent consumption, complex procedures, and elevated costs, highlighting the urgent need for novel processes and selective collectors for effective desilication and purification. Methods Microflotation experiments, zeta potential measurements, surface wettability analyses, FTIR, XPS, AFM, and ToF-SIMS were employed to investigate the flotation selectivity and interfacial interaction mechanisms of N-hexadecyl-N-methylpiperidinium bromide (HMPB) in the reverse flotation desilication of smithsonite. Findings Outstanding separation performance was achieved at pH 7.0 with an HMPB dosage of 7.5 mg/L, yielding a zinc concentrate grade of 47.01% and a recovery of 93.69%. The ζ-potential, wettability, FTIR, and XPS analyses confirmed that HMPB selectively interact with oxygen sites on quartz via synergistic electrostatic and hydrogen-bonding interactions, significantly increasing surface potential, hydrophobicity, and adhesion work, while showing negligible influence on smithsonite. Furthermore, AFM and ToF-SIMS analyses revealed the formation of a continuous HMPB adsorption layer exclusively on the quartz surface, where the distribution of organic fragments strongly correlates with Si rather than Zn, confirming the pronounced selectivity of HMPB for quartz and its effectiveness in sustainable desilication and purification.