Abstract:The dispersion and flocculation behavior of muscovite suspensions in the presence of Ca 2+ and Mg 2+ are relevant for industrial processing of pre-concentrated muscovite from stone coal, a primary source of vanadium. In this study, the dispersion and flocculation behavior were investigated by means of sedimentation, zeta potential, and ion absorption experiments, as well as the force between particles and ion speciation calculations. The results indicated that the dispersion and flocculation behavior of muscovite particles without excess ions were in qualitative agreement with the classical DLVO theory. The muscovite particles aggregated mainly due to basal surface-edge interactions in acidic suspensions but were dispersed in alkaline suspension by electrostatic repulsion of the total particle surface. In acidic suspensions, the ability of muscovite to form dispersions of muscovite was increased with the decrease in the electrostatic attraction between the basal surface and the edge caused by the compression of the electric double layers withCa 2+ and Mg 2+ . In alkaline suspension, the main adsorption form of Ca 2+ and Mg 2+ on muscovite surface was the ion-hydroxy complexes. The flocculation behavior of muscovite was affected by the static bridge effect of the ion-hydroxy complexes.

Roasting and flotation are common techniques used in mineral processing, and they have increasingly been combined for the pre-concentration of muscovite from stone coal. The research was mainly to study flotation properties of muscovite after roasting at 200, 400, 600, 800 and 1000˝C, respectively. The changes of chemical and physical properties of muscovite during the roasting process were investigated by thermogravimetric analysis (TGA), Fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Zeta potential measurements, particle size analysis, and the BET surface area measurements. The results indicated that the dehydroxylation of crystal structure took place at temperatures over 600˝C. A large number of hydroxyl groups were removed from the crystal structure of muscovite at 600-1000˝C. The layer structure, surface element distribution, and electrical properties of muscovite remained after roasting. The flotation recovery of roasted muscovite samples increased with the increase in roasting temperature in the same flotation system, because the specific surface and the adsorption capacity of dodecylamine (DDA) were reduced when roasting temperature was over 600˝C. A suitable roasting temperature and dosage of reagents can be provided for the roasting-flotation of muscovite.

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