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    Wyświetlanie 1-6 z 6
    Tytuł:
    Application of low-field NMR in the study of flocculant-aided filtration process of coal tailings
    Autorzy:
    Guo, Zhimin
    Liang, Long
    Hu, Pengfei
    Powiązania:
    https://bibliotekanauki.pl/articles/1447424.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    filtration
    coal tailings
    NMR
    flocculation
    inherent moisture
    Opis:
    Preconditioning of coal tailings with flocculants is a useful technology to improve filtration performance. In this study, anionic and cationic polyacrylamides were used for the pretreatment coal tailings before filtration. Nondestructive and rapid measurement of the filter cakes of coal tailings at different filtration stages was conducted using a nuclear magnetic resonance (NMR). The transverse relaxation time (T2) results of NMR provided the information concerned the state of water in filter cake, showing that free water entrapped in larger pores was removed mainly during coal tailings filtration, and the pressure in this study cannot remove the inherent moisture of filter cake of coal tailings. The significant increase in the amplitude of T2 value between 0.1 and 1.0 ms revealed that the flocs collapsed into smaller ones with water entrapped in them during filtration. Comparing the NMR results with different flocculants shows that anionic polyacrylamide of 800 g/Mg produced a larger structure in the initial stage of filter cake formation. The final filter cake entrapped more water. The NMR results well validated the filtration experiments.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2021, 57, 3; 1-7
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental study of quartz classification in the enhanced gravity field using Falcon concentrator
    Autorzy:
    Zhang, Ling
    Yang, Lu
    Hou, Haochun
    Zhao, Yan
    Lin, Jun
    Zhang, Zeliang
    Bu, Caiyun
    Zheng, Xinran
    Fu, Dong
    Powiązania:
    https://bibliotekanauki.pl/articles/27323652.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    classification
    enhanced gravity field
    fine particles
    fish-hook
    Opis:
    The classification and separation of minerals happen in the traditional gravity separation simultaneously. This paper focuses on the classification performance of quartz particles in the enhanced gravity field. The classification efficiency of single quartz particles decreased then increased with the increase of rotational angular velocity, while it decreased with the increase of backwash water pressure. The classification efficiency of -0.5 +0.25mm, -0.25 +0.125mm, -0.125 +0.074mm, -0.074 +0.045mm and -0.045mm quartz was higher than the corresponding narrow size of -0.5mm quartz in general. The “fish-hook” phenomenon appeared in the partition curve of -0.5mm quartz under small/large rotational angular velocity and small backwash water pressure, and the dip point could be found in fine particles region, which indicated that the “fish-hook” was closely related with operating parameters and particle size. A medium rotational angular velocity and larger backwash water pressure could be helpful to avoid the appearance of “fish-hook” in fine particles region and achieve a better classification performance. This investigation is beneficial to understand the regularity of particle migration in the enhanced gravity field.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2023, 59, 6; art. no. 175242
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental and numerical study on the classification of a cyclonic field in a flotation column
    Autorzy:
    Li, Xiaoheng
    Li, Xiao
    Yan, Xiaokang
    Wang, Lijun
    Zhang, Haijun
    Powiązania:
    https://bibliotekanauki.pl/articles/109487.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    computational fluid dynamics
    cyclonic flow field
    cyclonic-static micro-bubble flotation column
    particle size distribution
    Opis:
    The cyclonic-static micro-bubble flotation column (FCSMC) performs well in fine mineral flotation. Compared to traditional flotation columns, its design innovatively introduces a cyclonic structure. The separation of middling and tailing occurs in the cyclonic flow field induced by a cyclonic reversal cone. In this study, the particle size distribution analysis and computational fluid dynamics (CFD) simulations were conducted to reveal the particle distribution law and the classification mechanism in cyclonic flow fields under different circulation pressures. The results showed that particle size showed the same distribution tendency as tangential velocity in the radial direction: both increase from the center and decrease around the wall. As circulation flux increased, the tangential velocity increased, and the particle size differences in the radial direction also increased. The position of the largest particles will move to outside as the largest value of tangential velocity migrates the outward in the radial direction. According to the particle size distribution of the feed, it can be adjusted to the flow field to change the particle distribution, thereby improving the efficiency of separation. This study has an important guiding significance for column design and adjustment of the operating parameters of the flotation process.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 3; 421-431
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on feature extraction and dynamic properties of bubbles in a liquid-phase flow field
    Autorzy:
    Peng, Deqiang
    Dong, Xianshu
    Fan, Yuping
    Ma, Xiaomin
    Powiązania:
    https://bibliotekanauki.pl/articles/109400.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    bubbles
    image processing
    trajectory
    probability distribution of diameter
    terminal velocity
    Opis:
    To study the dynamic properties of bubbles generated at different air pressures in a liquid-phase flow field, this paper adopted high-speed camera technology and image processing techniques to extract and calculate the features of bubbles. The results showed that in a deionized water field, the bubbles generated at the air pressure of 0.1 MPa had an average diameter of 4.50 mm, and the bubbles generated at the air pressures of 0.2 MPa and 0.3 MPa had average diameters of 5.74 mm and 5.76 mm respectively; notwithstanding the insignificant differences in average data, the probability distribution of bubble diameter had significant differences with different pressures. During the rise of bubbles, their motion trajectory witnessed an increased amplitude of swing with the increase of air pressure; the bubbles generated at different air pressures did not show any significant differences in rising velocities though.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 1; 268-277
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on condition prediction and influencing factors of manganese carbonate recovery by high gradient pulse magnetic separation
    Autorzy:
    Wang, Zhenggang
    Nie, Guanghua
    Tang, Yun
    Piao, Haishan
    Chen, Jian
    Powiązania:
    https://bibliotekanauki.pl/articles/24085829.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    mineral particles
    impulse
    volume susceptibility
    magnetic field strength
    DLVO theory
    Opis:
    Manganese carbonate ore belongs to weakly magnetic minerals, and its co-associated minerals are mainly non-magnetic minerals, which can be separated from gangue minerals at high magnetic field intensity. However, manganese grade and recovery of magnetic separation concentrate of manganese carbonate ore are low in actual production. Therefore, the influences of manganese carbonate particle size, magnetic field intensity, volume susceptibility, pulse stroke, pH, and other factors were studied. The optimal test conditions for manganese carbonate ore recovery by high-gradient magnetic separation were predicted through the calculation results. The results show that the particle radius of manganese carbonate is 0.020 mm, the pulse impulse time is 200 r/min, and the magnetic field intensity is 0.9 T. The optimum condition test was carried out with Qianbei manganese carbonate ore as the material. The test results show that the optimum conditions are the particle radius of 0.074-0.019 mm, pulse impulse time of 200 r/min, and magnetic field intensity of 1.2 T. The reason for the deviation is that the actual ore has a fine distribution particle size, many associative bodies, complex composition, and serious agglomeration, resulting in variable particle volume susceptibility. The capture yield increases with the increase of magnetic field intensity and volume susceptibility but decreases with the increase of pulse. The lower the surface potential of manganese carbonate, the higher the recovery of manganese carbonate. The grade of manganese concentrate was 19.06% and the recovery was 76.85%. Mixed manganese concentrate with a grade of 18.04% and recovery of 87.14% was obtained by adding drugs and changing the grinding method.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2023, 59, 3; art. no. 168668
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on the floc-bubble adhesion behavior of hematite in static flow field
    Autorzy:
    Zhang, Jinxia
    Feng, Hongjun
    Niu, Fusheng
    Sun, Weiguang
    Zhao, Yawei
    Powiązania:
    https://bibliotekanauki.pl/articles/1449769.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    bubble
    floc
    adhesion
    charge-coupled device (CCD) camera
    Derjaguin-Landau-Verwey-Overbeek (DLVO) theory
    Opis:
    To investigate the adhesion of hematite flocs to gas bubbles in floc floatation, this paper develops an observation system for floc-bubble collision and adhesion with two charge-coupled device (CCD) cameras. The sizes of flocs and bubble were 45.36μm and 0.90mm, respectively, and the distance between a floc and the bubble center (sedimentation distance) was set to 0.25cm. Three surfactants, namely, sodium oleate, lauryl amine and sodium dodecyl sulfate (SDS), were selected for our research. Several experiments were conducted to disclose how surfactant concentration and pH affect the surface adhesion between hematite flocs and bubbles. Then, the adhesion mechanism was discussed in details based on the experimental results. The results show that the highest adhesion probability was achieved for the said floc and bubble at the lauryl amine concentration of 8mg/L, the sedimentation distance of 0.25cm and the pH of 9. After touching the bubble, the hermamite floc slid on the bubble surface, forming a stable three-phase interface after 67ms. Then, the radial position of the floc no longer changed, despite the floc motion on the bubble surface. According to the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and the potential energy of the van der Waals force, there was a repulsive force between the floc and the bubble in the absence of surfactant and an attractive force in the presence of the surfactant of lauryl amine. In addition, a thin solvation shell is conducive to the adhesion between the floc and the bubble.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 1; 124-133
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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