فهرست نشریات علمی دسترسی آزاد ایران

This study systematically evaluates the role of a mixed mono- and di-rhamnolipid biosurfactant in modulating the flotation behavior of non-copper minerals in a complex Cu–Fe–Mo–silicate ore. Using a full factorial design incorporating six operational variables (particle size: 75–105 µm; solids: 20–30%; frother: 0–20 g/t; collector: 0–40 g/t; rhamnolipid: 0–20 g/t; pH: 9–12), the metallurgical responses of Fe, Mo, SiO₂, and Al₂O₃ were quantified. Analysis of variance (ANOVA) confirmed the model's high significance and predictive accuracy. Rhamnolipid addition induced a distinctly selective response: Fe and Mo recoveries decreased by 12–18% on average, whereas SiO₂ and Al₂O₃ recoveries increased by approximately 35–40%—despite negligible changes in grade. This contrasting behavior is attributed to (i) a physical mechanism, where rhamnolipid markedly enhances bubble population density and froth stability, increasing entrainment of fine silicates; and (ii) a physicochemical mechanism involving hydrogen bonding between rhamnolipid carboxyl/hydroxyl groups and surface oxygen sites on quartz and phyllosilicates, thereby improving their hydrophobicity. In contrast, the depression of Fe–Mo minerals appears to arise from competitive adsorption between rhamnolipid and xanthate collectors, reducing sulfide hydrophobicity. Overall, rhamnolipid demonstrates dual functionality as a depressant for Fe–Mo sulfides and an activator for oxide/silicate gangue, offering strong potential as an environmentally benign modifier. The ~40% recovery enhancement of SiO₂/Al₂O₃ highlights its relevance for desilication or reverse-flotation applications, while its biodegradability aligns with green-chemistry directives. The findings offer actionable guidance for integrating biosurfactants into industrial flotation reagent schemes and underscore the need for future surface-analytical validation of the proposed mechanisms.