DEM investigation of rock/bolt mechanical behaviour in pull-out tests
Publication date: Available online 3 February 2020Source: ParticuologyAuthor(s): Na Che, Huaning Wang, Mingjing JiangAbstractRock bolt anchorage performance is crucial for tunnel support safety. We investigate the mechanical behaviour of reinforced rock and the bolts that reinforce it from the micro-scale to the macro-scale. Bolt pull-out tests were performed on soft rock using the distinct element method, in which a new contact model that considers bond size, is employed to constrain the main rock mechanical behaviour. The minimum sample width and height values for which the boundary effect can be neglected are first prop...
Source: Particuology - February 5, 2020 Category: Science Source Type: research
Editorial Board
Publication date: February 2020Source: Particuology, Volume 48Author(s): (Source: Particuology)
Source: Particuology - January 27, 2020 Category: Science Source Type: research
Preface
Publication date: February 2020Source: Particuology, Volume 48Author(s): Ning Yang, Liang-Yin Chu (Source: Particuology)
Source: Particuology - January 27, 2020 Category: Science Source Type: research
Scale-up effect analysis and modeling of liquid–solid circulating fluidized bed risers using multigene genetic programming
Publication date: Available online 23 January 2020Source: ParticuologyAuthor(s): Shaikh A. Razzak, Saddam A. Al-Hammadi, Syed M. Rahman, Mohammad R. Quddus, Mohammad M. Hossain, Jesse ZhuAbstractUnderstanding scale-up effects on the hydrodynamics of a liquid‒solid circulating fluidized bed (LSCFB) unit requires both experimental and theoretical analysis. We implement multigene genetic programming (MGGP) to investigate the solid holdup and distribution in three LSCFB systems with different heights. In addition to data obtained here, we also use a portion of data sets of LSCFB systems developed by Zheng (1999) and Liang et...
Source: Particuology - January 24, 2020 Category: Science Source Type: research
Influence of the rolling-resistance-based shape of coarse particles on the shear responses of granular mixtures
Publication date: Available online 23 January 2020Source: ParticuologyAuthor(s): Yangui Zhu, Zhihong Nie, Jian GongAbstractShear responses of dense granular mixtures of spherical coarse particles with the rolling resistance and spherical fine particles are studied via triaxial compression tests using the discrete element method. The macroscale responses (shear strength and dilatancy) are examined. Comparing the results with those in the literature indicates that granular mixtures with a rolling resistance coefficient of 0.5 have similar macroscale responses to those of gravel-shaped coarse particle mixtures. We quantify th...
Source: Particuology - January 24, 2020 Category: Science Source Type: research
Production of metallic iron nanoparticles in a baffled stirred tank reactor: Optimization via computational fluid dynamics simulation
Publication date: Available online 23 January 2020Source: ParticuologyAuthor(s): Giorgio Vilardi, Nicola VerdoneAbstractThe aim of this work is to optimize iron nanoparticle production in stirred tank reactors equipped with two classical impellers: Rushton and four-pitched blade turbines, which are largely used in batch industrial synthesis and efficient scale-up. The main operative parameters of nanoparticle synthesis are the precursor initial concentration, reducing agent/precursor molar ratio, impeller–tank clearance, and impeller rotational velocity. These parameters were varied during the synthesis to find the optim...
Source: Particuology - January 24, 2020 Category: Science Source Type: research
Image-based numerical study of three-dimensional meso-structure effects on damage and failure of heterogeneous coal-rock under dynamic impact loads
Publication date: Available online 21 January 2020Source: ParticuologyAuthor(s): Kehong Zheng, Bingjing Qiu, Zhenyu Wang, Xuefeng Li, Jianping Li, Kuidong GaoAbstractThis paper proposes a numerical three-dimensional (3D) mesoscopic approach based on the discrete element method combined with X-ray computed tomography (XCT) images to characterize the dynamic impact behavior of heterogeneous coal-rock (HCR). The dynamic impact loading in three directions was modelled to investigate the effects of the 3D meso-structure on the failure patterns and fracture mechanism, with different impact velocities. The XCT image-based discret...
Source: Particuology - January 22, 2020 Category: Science Source Type: research
Enhanced roasting of lepidolite for high defluorination efficiency in a fluidized bed reactor
Publication date: Available online 21 January 2020Source: ParticuologyAuthor(s): Jun Li, Jing Kong, Qingshan Zhu, Hongzhong LiAbstractDefluorination roasting of lepidolite ore in a fluidized bed reactor has been proposed for improving the extraction efficiency of lithium. In this paper, a vacuum was introduced to the fluidized bed reactor, which significantly improved the defluorination efficiency of lepidolite particles. This improvement could be attributed to an increase in the H2O/HF ratio. The highest defluorination rate for the lepidolite particles was obtained in the fluidized bed reactor under vacuum. The rate in th...
Source: Particuology - January 22, 2020 Category: Science Source Type: research
Onset of slugging fluidization in supercritical water fluidized bed
Publication date: Available online 11 January 2020Source: ParticuologyAuthor(s): Hao Wang, Jikai Huang, Youjun LuAbstractThe supercritical-water fluidized bed (SCWFB) is a reactor for coal and biomass gasification without pollutant emission. We carried out a series of experiments in a SCWFB, and a dual-capacitance probe measurement system was applied to measure the hydrodynamics of slugs, such as the slug frequency, chord length, and rising velocity. Four groups of Geldart-B particles with different mean diameters were fluidized by supercritical water with a system pressure of 20–27 MPa and at 410–570 °C. Th...
Source: Particuology - January 12, 2020 Category: Science Source Type: research
Fluidization behavior and reducibility of iron ore fines during hydrogen-induced fluidized bed reduction
Publication date: Available online 10 January 2020Source: ParticuologyAuthor(s): Daniel Spreitzer, Johannes SchenkAbstractA laboratory fluidized bed reactor was used to investigate the fluidization behavior and reducibility of various iron ore fines. Hydrogen was chosen as a reducing agent across a temperature range of 873–1073 K. The magnetite ore used exhibited strong sticking behavior after the initiation of metallic iron formation. All other tested ores fluidized sufficiently well when subjected to the same high reduction temperatures. Parallel kinetic analysis was conducted using a previously developed model to...
Source: Particuology - January 12, 2020 Category: Science Source Type: research
Effect of non-spherical particles on burning behavior during aluminum combustion
Publication date: Available online 6 January 2020Source: ParticuologyAuthor(s): Jinyun Wang, Zailin Yang, Mengjun WangAbstractThe shape of an aluminum particle is assumed to be spherical or an equivalent sphere during the combustion process. Such an assumption lacks objectivity and leads to unreasonable approximations of burning efficiency and performance. To investigate the influence of non-spherical particles on burning behavior, this study focused on a theoretical and experimental investigation of the combustion of nanoscale aluminum ellipsoidal particles. Models for prolate and oblate spheroids in aluminum combustion w...
Source: Particuology - January 8, 2020 Category: Science Source Type: research
Three-dimensional heat transfer in a particulate bed in a rotary drum studied via the discrete element method
Publication date: Available online 6 January 2020Source: ParticuologyAuthor(s): Esmaeil Yazdani, Seyed Hassan HashemabadiAbstractWe simulated three-dimensional heat transfer inside a horizontal rotating drum using the discrete element method and a thermal conduction model. The aim was to determine the effect of end-wall heating on thermal behavior of a granular bed. The simulation showed that the end-wall heating significantly affects the axial temperature profile of the bed, particularly when the length-to-diameter ratio is low. Particles near the wall heated faster and became more thermally uniform than those in the cent...
Source: Particuology - January 8, 2020 Category: Science Source Type: research
Validation of CFD–DEM model for iron ore reduction at particle level and parametric study
Publication date: Available online 3 January 2020Source: ParticuologyAuthor(s): E DianyuAbstractIron ore reduction is a primary unit operation in current metallurgy processes and dominates the energy consumption and greenhouse gas (GHG) emissions of the iron-making process. Therefore, even a slight improvement of the energy efficiency or GHG emissions of iron ore reduction would yield considerable benefits to the cost of pig iron and, more importantly, to mitigation of the associated carbon footprint. The current study presents a discrete model that describes the iron ore reduction process for a single pellet. The transien...
Source: Particuology - January 3, 2020 Category: Science Source Type: research
Determination of void boundary in a packed bed by laser attenuation measurement
Publication date: Available online 3 January 2020Source: ParticuologyAuthor(s): Yuanxiang Lu, Zeyi Jiang, Xinru Zhang, Sihan Liu, Jingsong Wang, Xinxin ZhangAbstractVoids are important regions in some industrial processes, particularly in the iron-making process, because a void is a zone in which gas–solid heat transfer and reactions occur. This paper presents a 3D experimental study of void formation measurement with 2D projection in a packed bed using an optical method. By developing an experimental laser-attenuation scanning method, invisible voids that form in a packed bed can be detected and identified as relatively...
Source: Particuology - January 3, 2020 Category: Science Source Type: research
Prediction of interphase drag coefficient and bed expansion using a variational model for fluidization of small spherical particles
In this study, we applied the variational model to fluidization of small spherical particles. Fluidization experiments were carried out for spherical particles with 13 diameters between dp = 0.13 and 5.00 mm. We propose a generalized form of our variational model to predict the superficial velocity U and interphase drag coefficient β by introducing an exponent n to describe the different dependences of the drag force Fd on fluid velocity for different particle sizes (different flow regimes). By comparing the predictions with the experimental results, we conclude that n=1 should be used for small particles (...
Source: Particuology - December 31, 2019 Category: Science Source Type: research
