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In this study, we investigated the effect of the scrubbing medium's particle size distribution on the scrubbing flotation performance of microcrystalline graphite. A simplex lattice mixture design approach using Design-Expert software was employed for proportioning testing of the scrubbing media. Three different sizes of scrubbing medium (A: 1 mm, B: 2 mm, and C: 3 mm) were mixed to obtain different particle size distributions. The results showed that a linear mixture model was suitable for fitting this mixture design, and the particle size distribution of the scrubbing medium was 3 mm. Hence, we studied the effect of scrubbing time on the flotation performance of the scrubbing flotation process. The flotation results indicated that graphite quality was enhanced by increasing the scrubbing time, and the optimum scrubbing time for this graphite was 45 min when maximum enrichment efficiency was acquired. Also, we investigated the effect of the scrubbing medium's particle size compositions on gangue entrainment in the scrubbing flotation process. It was concluded that the degree of entrainment under the composition of scrubbing size 1 mm (16.67%), 2 mm (16.67%), and 3 mm (66.66%) was reduced compared to the other two compositions (scrubbing size 2 mm (50%) and 3 mm (50%) as well as scrubbing size 3 mm (100%)). This conclusion was proved using analyses of froth bubble size and scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM-EDS). [ABSTRACT FROM AUTHOR]

Bulk micro-nano-bubbles (BMNBs) have been proven to be effective at improving the flotation recovery and kinetics of fine-grained minerals. However, there is currently no research reported on the correlation between the properties of BMNBs and flotation performance. For this purpose, aqueous dispersions with diverse properties were created by altering preparation time (0, 1, 2, 3, 5, and 7 min), aeration rate (0, 0.5, 1, 1.5, and 2 L/min) and aging time (0, 0.5, 1, and >3 min). Micro- and nano-bubbles were characterized using focused beam reflection measurements (FBRM) and nanoparticle tracking analysis (NTA), respectively. The micro-flotation of quartz particles was performed using an XFG-cell in the presence and absence of BMNBs with Cetyltrimethylammonium bromide (CTAB) as a collector. The characterization of bubble sizes showed that the bulk micro-bubble (BMB) and bulk nanobubble (BNB) diameters ranged from 1–10 μm and 50–400 nm, respectively. It was found that the preparation parameters and aging time considerably affected the number of generated bubbles. When BNBs and BMBs coexisted, the recovery of fine quartz particles significantly improved (about 7%), while in the presence of only BNBs the promotion of flotation recovery was not significant (2%). This was mainly related to the aggregate via bridging, which was an advantage for quartz flotation. In comparison, no aggregates were detected when only nano-bubbles were present in the bulk solution. [ABSTRACT FROM AUTHOR]

In this study, interaction between coarse and fine coal particles during flotation was investigated with aid of FBRM and PVM, and explicated by the extended Derjaguin–Landau–Verwey–Overbeek (EDLVO).The flotation results showed that coarse coal particles could greatly improve the flotation of fine coal. Analyzing the results of FBRM and PVM revealed that the improvement in the flotation of fine particles was attributed to the fact that a portion of fine coal accumulated or adhered to coarse coal. This is because the total interaction between coarse and fine particles was attractive based on the theoretical calculation of EDLVO. [ABSTRACT FROM AUTHOR]

• Ultrasonic parameters of graphite flotation were optimized by Box–Behnken design. • Horn-type ultrasound produced a better flotation efficiency than that of bath-type. • Dual-frequency ultrasound was first employed for graphite flotation. • Related mechanisms are cavitation intensity and formed bubble-particle aggregates. Ultrasound has emerged as a promising technique for improving the mineral flotation performance. However, limited research exists regarding the influence of different ultrasound types on the flotation process. Specifically, the impact of combined ultrasound and the comparison of horn- and bath-type ultrasounds on flotation have not been fully investigated. To address this knowledge gap, a comprehensive study to explore the effects of different ultrasonic pretreatments on the flotation of flake graphite was conducted. A Box-Behnken design is employed to analyze the effects of combined ultrasound on graphite flotation. By characterizing the properties of graphite samples before and after the ultrasonic treatment, the aim is to elucidate the mechanism underlying the impact of ultrasound on graphite flotation. The experimental results indicated that the ultrasonic cavitation intensity exerted a significant influence on the graphite flotation recovery. Both horn- and bath- type ultrasounds contributed to flotation, but horn-type ultrasound demonstrated a more pronounced effect, leading to a 7% increase in flotation recovery, whereas bath-type ultrasound resulted in only a 2% increase. Furthermore, the cavitation intensity of combined ultrasound was found to be higher than that of single-frequency ultrasound in the same duration. However, the performance of graphite flotation was better with short duration combined ultrasound pretreatment, while the opposite trend was observed for a long duration ultrasound pretreatment. These findings may inform the development of more efficient and effective ultrasonic pretreatments for flotation separation processes. [ABSTRACT FROM AUTHOR]

• Micron- and nano-droplets of emulsified kerosene were prepared. • Nanodroplets enhanced bubble coalescence and froth drainage better. • Nanodroplets inhibited entrained gangue and favored selective flotation of graphite. In this study, kerosene emulsions with different average droplet sizes (700 nm, 854 nm, and 996 μm) were prepared to investigate their effects on the entrainment of gangue materials and the selectivity index in the flotation of aphanitic graphite. The calculation results based on Neethling and Cillers's model indicate that a decrease in the average droplet size of emulsified kerosene would result in a decrease in the entrainment of gangue materials, which corresponds to the observations of froth layer height, maximum water recovery rate, and bubble size in the top section of the froth zone. This may be ascribed to the enhanced collision probability between graphite particles and oil droplets, as well as the increased modified flotation rate constant compared to the micro-scale droplets. It is also noted that the selectivity index in graphite flotation increases as the average droplet size of kerosene emulsions decreases. This is largely due to the synthetic effect of the mitigated gangue entrainment and the intensified collision between graphite particles and oil droplets in the presence of nano-scale oil droplets. [ABSTRACT FROM AUTHOR]

• Combined cavitation bubbles and carrier flotation to upgrade ultra-fine particles. • Utilized FBRM and PM techniques to directly observe the strengthening mechanisms. • Applied E-DLVO theory to evaluate the interaction energy for the novel process. In this paper, a novel flotation technique that combines nano-scale bubbles generated by hydrodynamic cavitation (HC) and carrier flotation is proposed to promote the flotation efficiency of a high-ash (43%) ultra-fine coal sample (<45 µm). We investigated the mechanism by which cavitation bubbles enhance the separation efficiency of carrier flotation using focused beam reflectance measurements, polarizing microscopy, and extended Derjaguin–Landau–Verwey–Overbeek theory. The carrier particles (polystyrene (PS)) and fine coal were pre-treated in a venturi tube and then floated in a laboratory mechanical flotation cell. The flotation results indicate that the presence of cavitation bubbles significantly improved the carrier flotation performance of high-ash ultra-fine coal. This improvement was attributed to the presence of highly hydrophobic PS, which creates additional gas nuclei in the flotation system. The nano-bubbles, which were produced by the venturi tube and adhered to the fine coal particle surfaces, were conducive to the agglomeration of fine coal particles into large aggregates. Moreover, the nano-bubbles functioned as "bridges" of interaction between the carrier particles and large aggregates of fine coal particles. This paper mainly focused on the effect of carrier (PS) and HC on high-ash fine coal. The influence of different HC intensities on carrier (PS) flotation was discussed. Two models for the interactions between the coal particles, nano-bubbles, and PS during cavitation were proposed and were proved using the E-DLVO theory. [ABSTRACT FROM AUTHOR]

[Display omitted] • β-cyclodextrin/kerosene Pickering emulsion were prepared. • Effects of factors on the droplet size and stability of emulsion were investigated. • Response surface methodology was used to obtain optimal preparation conditions. • A proper β-cyclodextrin dosage used for emulsification promoted graphite flotation. • Mechanism of Pickering emulsion on graphite flotation was discussed. Pickering emulsions use nanoparticles to reduce the amount of emulsifiers and generate environmentally friendly reagents; this can be employed in different processes. However, there are no published reports on the application of Pickering emulsions in mineral beneficiation by flotation separation. Collector emulsification is an effective way to improve flotation performance. β-cyclodextrin is a granular emulsifier that has been widely considered in various investigations. As a comparative investigation, this study explored the application of the β-cyclodextrin/kerosene Pickering emulsion as a collector for the flotation beneficiation of a low-grade graphite ore. The response surface design was applied to investigate the influence of the water phase ratio, β-cyclodextrin weight, stirring time, stirring intensity, and the interaction of these factors on the emulsion droplet size and emulsion stability. The β-cyclodextrin weight optimization test showed that the Pickering emulsion reached its optimum flotation performance when the weight of β-cyclodextrin was 0.10 g. Surface analyses (zeta potential and contact angle measurements) indicated that the emulsion is stabilized by vesicles, which are self-assembled by inclusion compounds formed by kerosene and β-cyclodextrin. The developed Pickering emulsion could improve graphite recovery by 6%. [ABSTRACT FROM AUTHOR]

• Microcrystalline graphite was enriched efficiently under scrubbing flotation. • Response surface methodology was used for the optimization of scrubbing flotation. • The most significant parameter of scrubbing flotation was scrubbing medium size. • Effect of scrubbing medium size on mineralogical characteristics was evaluated. Scrubbing is a suitable method for cleaning fine slime on the surface of microcrystalline graphite, improving its flotation performance. However, little attention has been paid to the effect of the scrubbing medium's particle size on enrichment efficiency of scrubbing flotation of microcrystalline graphite. In this work, scrubbing parameters (i.e., scrubbing medium's particle size, stirring speed, and solid concentration) were optimized via response surface methodology using Box-Behnken design to yield the maximum enrichment efficiency of graphite ore. The scrubbing medium's particle size was found to be the most important influencing factor. The optimal conditions for scrubbing process were obtained and tested to confirm the results predicted by the Design-Expert software. The enrichment efficiency of graphite treated with scrubbing media of different sizes was compared under optimal stirring speed and solid concentration conditions. The effect of the scrubbing medium's particle size on the scrubbing flotation of graphite was investigated by a comparison of the graphite particle size distribution before and after scrubbing, and field emission scanning electron microscopic examination of raw ore and flotation concentrates. [ABSTRACT FROM AUTHOR]