Abstract
The mixed cationic collector cetyltrimethylammonium chloride (CTAC) and nonionic collector octanol (OCT) was found to exhibit a synergistic effect on the flotation and adsorption of muscovite. To understand the underlying synergistic mechanism, flotation, contact angle, surface tension, and adsorption measurements were carried out. The results obtained from flotation measurements indicated that the mixed CTAC/OCT exhibits a better collecting ability than CTAC or OCT. The recovery of muscovite with CTAC only rapidly decreased from 97.25% at pH 2.64 to 75.26% at pH 5.82, followed by a flat horizontal at a pH is higher than 6. In contrast, a high recovery of greater than 85% muscovite was observed using mixed CTAC/OCT at α CTAC = 0.67 (the mole ratio of CTAC:OCT = 2:1) over the investigated pH range. From the surface activity parameters (CMC, γ CMC, Γmax, Amin) estimated from surface measurements and interaction parameters (βm, βσ), in addition to the micellar and interfacial compositions ( x 1 m , x 1 σ ) obtained from the theory of regular solutions, a synergistic effect is evident in the mixed micelle and at the water/air interface. Moreover, the mixed CTAC/OCT at α CTAC = 0.67 exhibited the maximum synergistic interaction. The results obtained from surface tension measurements indicated that the mixed CTAC/OCT exhibits considerably higher surface activities compared to single CTAC or OCT. The contact angle results confirmed that the mixed CTAC/OCT is a better collector than the individual CTAC or OCT for the flotation of muscovite. According to the results obtained from adsorption experiments, compared with that of individual CTAC or OCT, the amounts of CTAC and OCT adsorbed on the muscovite surface are considerably increase in the mixed systems because of co-adsorption. Based on these results, the mixed CTAC/OCT exhibits a remarkable synergistic effect during the flotation and adsorption of muscovite.
Highlights
Muscovite has been commonly used in a wide range of industrial applications because of its distinctive properties, e.g., dielectric properties, heat resistance, and chemical resistance [1]
The contact angle results confirmed that the mixed cetyltrimethylammonium chloride (CTAC)/OCT is a better collector than the individual CTAC or OCT for the flotation of muscovite
The contact angle test only reflects the properties of the cleaved muscovite surface, but does not consider the edge surface, which affects the flotation behavior
Summary
Muscovite has been commonly used in a wide range of industrial applications because of its distinctive properties, e.g., dielectric properties, heat resistance, and chemical resistance [1]. It is a typical two-layer-structured aluminosilicate, with a negatively charged tetrahedral layer owing to the isomorphic substitution of approximately 1/4 Si4+ ions by Al3+ ions. These permanent charges are balanced by the interlayer K+ ions, which serve as a bridge between the sheets [2,3]. Several silicates accompanying muscovite are negatively charged under neutral or alkaline conditions and are Minerals 2017, 7, 74; doi:10.3390/min7050074 www.mdpi.com/journal/minerals
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