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  • MDPI AG  (4)
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  • MDPI AG  (4)
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  • 1
    In: Minerals, MDPI AG, Vol. 9, No. 1 ( 2019-01-09), p. 30-
    Abstract: Biodiesel was found to be a more effective collector on low-rank coal flotation than the common oily collectors (diesel and kerosene) in previous research. However, the micro-adsorption behavior of these collectors on the coal surface remains to be further explored. In the present work, the adsorption behavior of methyl laurate and dodecane, representing biodiesel and common oily collectors, was investigated using experimental and molecular dynamics (MD) simulation methods. The results of MD simulations showed that dodecane was difficult to diffuse on the surface of sub-bituminous coal and formed a spherical structure on the surface of sub-bituminous coal. Methyl laurate was adsorbed on the surface of coal via the head group (ester group), while the tail group (alkyl chain) was exposed to a liquid environment, forming a wider network structure on the coal surface. The above results, mainly attributed to methyl laurate, had a higher interaction with the sub-bituminous surface compared to dodecane. The self-diffusion coefficient results showed that the aggregate configurations of methyl laurate cause higher water mobility, which was more conducive to enhancing the hydrophobicity of the coal surface. The adhesion efficiency measurement and X-ray photoelectron spectrometer (XPS) analysis confirmed that methyl laurate could cover more oxygen-containing functional groups on the coal surface than dodecane, thus enhancing the hydrophobicity of coal. The results of simulations conformed to the experimental results.
    Type of Medium: Online Resource
    ISSN: 2075-163X
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2655947-X
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  • 2
    In: Processes, MDPI AG, Vol. 6, No. 11 ( 2018-11-05), p. 218-
    Abstract: The collision and adhesion behavior of particles and bubbles is the key to flotation. Many scholars have investigated the collision and adhesion law of regularly shaped and homogeneous particles (glass beads, glass fiber), but the particles in flotation cells are irregular and heterogeneous. Therefore, it is necessary to take actual coal samples as the research object. First, based on previous research, a particle–bubble collision and adhesion behavior measurement device was set up to study free falling coal particles with different surface properties colliding and adhering to a bubble (db = 1.0 mm). Then bituminous coal from Inner Mongolia was taken as the test object, and the collision and adhesion process of a large amount of coal particles was traced. The entire process is photographically recorded by a camera and analyzed frame by frame through a self-designed software. Finally, the relationship between collision angle and initial settlement position (initial), particle velocity (process), and adhesion efficiency (result) was studied by taking the collision angle as the cut-in point. It was found that both the distribution range of the initial settlement position and the particle central distribution interval are expanding outward with the increase of collision angle. The resistance layer has an important influence on the velocity of particles. The collision angle had an effect on adhesion efficiency and the adhesion efficiency of low-density particles was higher than that of high-density particles.
    Type of Medium: Online Resource
    ISSN: 2227-9717
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2720994-5
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  • 3
    Online Resource
    Online Resource
    MDPI AG ; 2020
    In:  Molecules Vol. 25, No. 17 ( 2020-09-03), p. 4030-
    In: Molecules, MDPI AG, Vol. 25, No. 17 ( 2020-09-03), p. 4030-
    Abstract: To study the effects of different oxygen functional groups on the quality of flotation clean low-rank coal, two kinds of collectors with different oxygen-containing functional groups, methyl laurate, and dodecanol, were selected and their flotation behaviors were investigated. The Bulianta coal was the typical sub-bituminous coal in China, and the coal molecular model of which was constructed based on proximate analysis, ultimate analysis, 13C-NMR, and XPS. The chemical structure model of the coal molecule was optimized, and the periodic boundary condition was added via the method of molecular dynamics methods. The different combined systems formed by collectors, water, and a model surface of Bulianta coal have been studied using molecular dynamics simulation. The simulation results of dodecanol and methyl laurate on the surface of Bulianta coal show that dodecanol molecules are not evenly adsorbed on the surface of coal, and have higher adsorption capacity near carboxyl and hydroxyl groups, but less adsorption capacity near carbonyl and ether bonds. Methyl laurate can completely cover the oxygen-containing functional groups on the coal surface. Compared with dodecanol, methyl laurate can effectively improve the hydrophobicity of the Bulianta coal surface, which is consistent with the results of the XPS test and the flotation test.
    Type of Medium: Online Resource
    ISSN: 1420-3049
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2008644-1
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  • 4
    Online Resource
    Online Resource
    MDPI AG ; 2022
    In:  Processes Vol. 11, No. 1 ( 2022-12-29), p. 102-
    In: Processes, MDPI AG, Vol. 11, No. 1 ( 2022-12-29), p. 102-
    Abstract: The accurate determination of the coal slime filter cake pore structure has always been a problem in the field of solid–liquid separation. An innovative measurement method for the pore structure of filter cake after filtration dehydration of coal slime water, including the preparation of coal slime filter cake, the solidification of the filter cake, and the preparation and measurement of test filter cake, was established in this paper. Epoxy resin and curing agent can ensure the strength of the filter cake, and red colorant can realize the accurate separation of coal particles and pores. The most suitable perfusate consists of epoxy resin, red colorant, and curing reagent, and the optimal ratio is 12:3:5. The application of the method to the study of the effect of filtration time on the coal slime filter cake pores shows that the modified method is effective. At the initial stage of filtration, intergranular pores formed by coarse particles are the main pores. With increasing filtration time, the macropores formed by the coarse particles are mainly filled with fine particles, and the pore size of the filter cake rapidly decreases. These measuring results and rules are accurate. This method can be conveniently used to study the microstructure of filter cake, pore channel regulation, filtration dehydration mechanisms, etc.
    Type of Medium: Online Resource
    ISSN: 2227-9717
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2720994-5
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