Advanced Powder Technology最新文献

The flow field in an air classifier has complex dynamic characteristics, making it extremely unstable and difficult to monitor. Here, the time-domain pressure signals in an air classifier were measured at different rotational speeds and spatial locations using micro differential pressure dynamic sensors. The pressure signals were analyzed using the probability density function, standard deviation, and power spectral density. Moreover, a new type of predictive model combining the convolutional neural network, long and short-term memory, and the attention mechanism was proposed. The results show that, regardless of whether a screen cage is present, the pressure signals at different spatial locations in the gas-phase flow field have only one main frequency, which is caused by the quasi-forced vortex motion with the most intense fluctuations. However, PSD has only one main frequency under both load and no-load conditions, its value under load is 1.5 times higher, and the distribution of main frequencies is unaffected by solid loading at high rotational speeds (>40 Hz). Meanwhile, PSD and coherence analyses revealed that large eddies at the outlet induced low-amplitude pressure fluctuations in the high-frequency range. Finally, the proposed CNN-LSTM-A model outperformed traditional deep learning models (SVM and BPNN) in predicting the pressure fluctuations.

In this paper, a new series of Fe₂TiO₅ - polypyrrole (FTO-xP) were prepared by the facile polymerisation method using sulphuric acid and hydrogen peroxide as oxidising agents. The synthesised compounds were characterised by diffuse reflectance spectroscopy (DR/UV–vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), microscopic analysis (SEM) and specific surface area analysis (BET) to evaluate their optical and surface properties, morphology, phase composition and crystallinity. The new composites were used for photocatalytic removal of micropollutants: highly toxic Cr(VI) and ibuprofen (IBU). The effect of polypyrrole content in the composite on the efficiency of selected micropollutants degradation was investigated. The results showed that FTO-xP composites had better adsorption capacity and photocatalytic activity than single components. Hybrid FTO-xP composites could efficiently remove inorganic/organic micropollutants in the aqueous phase.

Fibrous filters are widely used to remove particles from gas-solid flows. In the present research, the potential to enhance the collection efficiency of fibrous filters was investigated by increasing the number of filter rows and using varying sizes of square fibers. A two dimensional model was used to simulate the transport and deposition of particles, employing the developed Eulerian-Lagrangian solver coupled with the Immersed Boundary (IB) method. Several structures of filter fibers including the equal and unequal fibers in the arrangement of two, four and six rows were investigated. The results showed increasing the size difference between large and small fibers in the filter media increases the collection efficiency and pressure drop simultaneously. To find the effective structure of enhancing the filter performance, the quality factor was considered. The results of quality factor showed that using unequal fibers has an advantage over increasing the number of rows in an equal-fiber structure to increase the collection efficiency. Therefore, using the unequal fibers with the growth rate of 1.2 to 1.4, are more effective than increasing the number of rows in equal fiber structures.

Dust control in machining brittle materials is critical for ensuring safety in production, for which ventilation through pipes and chambers is an effective means. Although particle transport and deposition inside pipes have been widely explored, limited attention has been given to those in a chamber, especially for a trapezoidal one, and the transport and deposition of particles inside such a chamber remain elusive. This study aims to address this issue through numerical simulations. Specifically, a group of particles is initially distributed on the inlet cross-sectional surface of the chamber according to the local fluid velocity, and is released and blown into the chamber at a certain instant. Herein, one-way coupling between the fluid and particles is considered, and a particle transport and deposition-rebound model based on Johnson–Kendall–Roberts (JKR) theory is employed. The influences of inlet velocity and particle size on particle transport and deposition are explored. The results reveal that the particle deposition rate and escape rate increase with inlet velocity, resulting in shorter residence time for particles in the chamber. Smaller particles typically have higher escape rates and lower deposition rates. The effects of fluid dynamics on particle transport and deposition are also analyzed.

This study, based on the construction of a wind flow-dust two-phase coupled diffusion model, develops a novel method using a prepositioned air distributor to create an air curtain for dust control. This research involved the analysis of wind flow transportation patterns and dust diffusion mechanisms with varying structural parameters, and the verification of simulation results through field tests. The findings indicate that with the increase of the axial horizontal opening angle of the prepositioned air distributor, the wind speed of the air curtain decreases, while the size of the vortex field in the heading face area expands. Increasing the axial vertical opening angle enhances the strength of the vortex, leading to improved dust control abilities. The dust concentration at the rear of the tunnel initially decreases and then rises. Additionally, as the turning angle increases, the speed at which the wind flow diffuses towards the rear of the tunnel also rises. Compared with traditional ventilation methods, the dust reduction efficiency at the respiratory zone height is improved to over 94.0 %. The concentration of dust within the tunnel is significantly reduced, with approximately 98.9 % of the dust confined within a 10.0 m range from the heading face.

Bluecoke powders pose challenges in large-scale industrial utilization due to their small particle size and low added value that become one of primary constraints on the coking industry. In this work, Fe catalyst-assisted microwave pyrolysis of low-rank coal to prepare the modified bluecoke powders containing carbon nanotubes (CNTs) was investigated, and their potential applications were discussed. The results showed that when the addition ratios of Fe(NO₃)₃ and Fe(C₅H₅)₂ were 0.05 and 0.15 respectively, the yields of CNTs in the modified bluecoke powders were 4.77 wt% and 4.15 wt%, with diameters primarily range of 50–135 nm and 30–80 nm. Additionally, the specific surface area reached 1306.29 m²/g and 643.76 m²/g. Fe(C₅H₅)₂ significantly influenced the MBPs, and Fe and Fe₃C played pivotal roles in the growth of CNTs. The excellent adsorption property and good electrochemical activity of the MBPs exhibited their considerable potential applications.

Fine hollow nickel (Ni) and cerium (Ce) oxide (Ni_xCe_1−xO_2−x) composite particles were synthesized from nickel and cerium nitrates by spray pyrolysis with citric acid as a templating additive. The synthesis of Ni_xCe_1−xO_2−x solid-solution particles was achieved when the molar ratio of Ni in the starting material was 25 mol%. When the Ni molar ratio was higher than 33 mol%, the particles consisted of two crystalline phases: a solid solution and nickel oxide. Citric acid acted as a template and generated cavities inside the particles. Changing the concentration of citric acid enabled control of the internal structure of the particles. Solid particles with solid interiors, sponge-like particles with an internal network structure, and hollow particles with a large spherical internal cavity were produced by regulating the citric acid concentration.

The flotation separation of scheelite from calcite is challenging due to their similar surface and solution chemistry properties, necessitating the use of efficient inhibitors. This study explored the mixed depressant of ferric ion and gallic acid for enhancing separation efficiency of scheelite and calcite. The flotation performance of scheelite and calcite was evaluated with varying ferric ion to gallic acid molar ratio (1:5), concentrations (2 × 10^-5 mol/L and 1 × 10^-4 mol/L), and a NaOL dosage of 1 × 10^-4 mol/L. The results indicated that scheelite achieved a recovery of 81 % while calcite recovery was 8.3 %. The mixed ore experiment proved that the addition of mixed depressant increased the grade of scheelite by 21.48 % (from 37.08 % to 58.56 %) compared with that of only the addition of the collector. The experiment showed that the mixed depressant had a good inhibition effect on calcite. Surface characterization analysis indicated that the mixed depressant exhibited a weak depressive effect on scheelite but effectively depressed calcite by enhancing gallic acid adsorption through iron ions promotion of calcite surfaces, thereby inhibiting sodium oleate enrichment. Therefore, this study confirmed the mixed depressant was an effective depressant for calcite flotation in scheelite flotation separation.

As biochar exhibits a unique structure and electrical conductivity, application of biochar in batteries arouses huge attention. In the present study, the cassia seed-derived N-P double-doped porous carbon which acts as a carrier of sulfur cathode is prepared based on a fast, powerful puffing of cassia seed with subsequent annealing treatment route. After loading sulfur into the porous carbon, the carbon–sulfur composite is employed as the cathode material of lithium-sulfur batteries. It is found that by puffing process with the popcorn machine, cassia seeds can successfully change into porous carbon with numerous mesopores based on considerable large pores. This special architecture can effectively capture the lithium polysulfide intermediates and inhibit the volume of sulfur from expanding simultaneously. Meanwhile, the N-P double-doped carbon can alter the hybridization orbital of carbon and facilitate the chemical adsorption of lithium polysulfide, thereby expediting the cycle of S cathode. The N-P doped carbon–sulfur composite exhibits a maximum discharge capacity of 1464.4 mAh/g at 0.1C and maintains a high discharge capacity of 825.8 mAh/g after 100 cycles at 5C. This study presents an economical, green and sustainable method to synthesis N-P double-doped porous carbon–sulfur composite which has large-scale application prospects in lithium-sulfur batteries.

Zinc oxide nanostructures were synthesized using a thermal decomposition method and subsequently doped with Fe (III) in this study. Techniques such as X-ray diffraction, Field emission scanning electron microscopy, and Fourier transform infrared spectroscopy were used to investigate the structural and chemical composition of nanomaterials. Fe-doped ZnO was synthesized using a simple, low-cost planetary high-energy ball milling process. The sonophotocatalytic activity of Fe-doped ZnO under visible light and ultrasonic waves was then studied. Another aspect of this study is the utilization of visible light, which is far more accessible and cost-effective than UV light. Malachite green (MG) and phenol were applied as water-soluble contaminants. MG degraded about 87.65% after 1 h in the presence of a Fe-doped ZnO catalyst under visible light and ultrasonic waves simultaneously. Phenol was degraded by approximately 64.50% under the same conditions.