Cost-effective reverse flotation of smithsonite from quartz under neutral pH by employing a low-dosage cetylpyridinium bromide collector: Mechanistic insights into selective and efficient separation

This study proposes a novel reverse flotation strategy to overcome the limitations of conventional direct flotation of smithsonite from quartz, such as the need for strong alkalinity, high reagent dosages, and poor selectivity. Using cetylpyridinium bromide (CPB) as a collector under neutral pH conditions, selective separation was achieved with high efficiency. Microflotation tests demonstrated that at pH 7.0 and a CPB dosage of 10.0 mg/L, smithsonite recovery reached 94.20 %, and the quartz removal rate was 98.28 %. The separation index (SI) and separation efficiency (SE) were 30.46 and 93.19, respectively, significantly surpassing conventional direct flotation performance. Multiscale surface characterization techniques, including zeta potential measurements, contact angle analysis, FTIR, XPS, SEM-EDS, AFM, and ToF-SIMS, were employed to examine the interfacial interactions between CPB and the mineral surfaces. The results revealed that CPB selectively adsorbs onto quartz surfaces via electrostatic attraction between its cationic headgroups and deprotonated silanol groups ( Si–O − ), as well as hydrogen bonding with neutral silanol groups ( Si–OH). This approach simplifies flotation operation, reduces reagent consumption and processing costs, and enhances the resource efficiency of smithsonite, offering promising prospects for industrial application and theoretical development.