Effects of pore compression pretreatment on the flotation of low-rank coal

Yang, Zili; Xia, Yangchao; Li, Ming; Ma, Zhi-Sai; Xing, Yaowen; Gui, Xiahui

doi:10.1016/j.fuel.2018.10.145

Cited by 35 publications

(12 citation statements)

References 39 publications

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“…The oxidized coal has poor floatability because it contains a developed pore structure and abundant oxygen-containing functional groups, which result in a low attachment probability to the air bubbles and thus low flotation efficiency. 6 Therefore, it is important to develop a flotation process to enhance the attachment efficiency between oxidized coal particles and bubbles.…”

Section: Introductionmentioning

confidence: 99%

Effect of Nanobubbles on the Flotation Performance of Oxidized Coal

et al. 2020

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In this study, the effects of air bubbles and nanobubbles on flotation performance and kinetics of oxidized coal were investigated. The surface properties of the coal sample before and after oxidation were characterized by a scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The nanobubbles on highly oriented pyrolytic graphite (HOPG) were observed by an atomic force microscope (AFM). The interaction between coal and conventional bubbles in the absence and presence of nanobubbles was explained by induction time. Flotation results showed that oxidized coal flotation in the presence of nanobubbles resulted in 10% higher combustible matter recovery than conventional air bubble flotation. Moreover, it was found that the flotation of oxidized coal in the absence and presence of nanobubbles can be best described using the first-order model with the rectangular model. AFM images analysis showed that a large number of nanobubbles were produced and attached to the oxidized coal surface. The induction times of the oxidized coal in the absence and presence of nanobubbles were 1000 and 39 ms, respectively, indicating that the existence of nanobubbles effectively promotes the interaction between oxidized coal and macroair bubbles. In addition, the agglomeration between oxidized coal particles also occurred spontaneously in the presence of nanobubbles, which was helpful in improving the combustible matter recovery and flotation rate of oxidized coal.

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Section: Introductionmentioning

confidence: 99%

Effect of Nanobubbles on the Flotation Performance of Oxidized Coal

et al. 2020

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“…[1][2][3][4]. However, since a large number of hydrophilic oxygen-containing functional groups and pores exist on the low-rank coal, a stable hydration layer can be formed on the surface during the flotation process [5][6][7][8][9]. Therefore, the traditional oil flotation collector is difficult to adsorb on its surface, which ultimately leads to low flotation efficiency of low-rank coal [10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…In order to improve the flotation performance of low-rank coal, a great deal of research has been carried out in recent years [3,12,14,[16][17][18]. In general, the research was mainly conducted through the following three aspects: pretreatment technology, such as microwave [19], compressing [6], etc., to improve the surface hydrophobicity of low-rank coal; adding surfactant to improve the adsorption of hydrocarbon collector on the surface of low-rank coal; designing and developing new agents to improve the interaction between agents and low-rank coal surface [13,14,17,[20][21][22]. Lubricating oil was studied as a flotation collector for low-rank coal.…”

Section: Introductionmentioning

confidence: 99%

Effect of Hydration Layer on the Adsorption of Dodecane Collector on Low-Rank Coal: A Molecular Dynamics Simulation Study

et al. 2020

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The hydration layer has a significant effect on the adsorption behavior of reagents during the flotation process of low-rank coal. Understanding the effect of hydration layer on the adsorption of common collectors on low-rank coal is a prerequisite for proposing a new enhanced coal floatation method. In this study, a smooth low-rank coal surface model with a density of 1.2 g/cm3 was constructed and compared with the XPS results. Three different systems, coal-water, coal-collector, and coal-water-collector, were constructed. Molecular dynamics method was applied to study the adsorption behaviors of water and dodecane molecules. Simulation results revealed that a stable hydration layer with a thickness of about 5 Å was formed due to the strong attraction of coal surface. The negative value of interaction energy (IE) indicated that dodecane molecules could spontaneously adsorb on the coal surface. Dodecane molecules were successfully adsorbed on the coal surface when it was located inside the hydration layer. While the dodecane molecule was outside the hydration layer, it could not pass through the hydration layer on the surface of low-rank coal.

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“…6 Furthermore, the porosity and pore permeability of CFs further increases consumption of oily collectors. 7 Hence, conventional hydrocarbon oils are not effective and economical collectors in otation of low-rank coal.…”

Section: Introductionmentioning

confidence: 99%