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In Chemical Mechanical Polishing (CMP) using ceria-based abrasives, a key challenge is maintaining particle stability to ensure consistent, reproducible, and predictable polishing results. Given the combined nature of CMP, involving both chemical reactions and mechanical abrasion, it is widely believed that during the polishing process, chemical compounds from the glass dissolve into the slurry, leading to changes in its chemical composition, which can affect stability and particle size distribution. However, these assumptions have primarily been based on simulations or speculative suggestions rather than direct experimental evidence. To investigate this further, experiments were conducted using three types of glass representing high, medium, and zero alkali content polished with both 400 nm and 80 nm ceria abrasives. A substantial increase in the slurry pH was observed when polishing soda-lime-silicate and borosilicate glass with 400 nm abrasives, whereas the pH remained stable when polishing fused silica glass. Notably, polishing with 80 nm abrasives did not affect the pH levels across the different glass types. Zeta potential measurements, particle size distribution, and real-time imaging provided insights into ceria particle aggregation and dispersion. Scanning Electron Microscopy (SEM) further confirmed changes in particle behavior. The findings of this study demonstrate that the polishing of alkali-containing glasses using larger ceria abrasives alters slurry chemistry and modifies particle size distribution. These findings provide new insights into the complex interactions between slurry chemistry, particle size, and glass composition in CMP, highlighting the need for careful control of abrasive properties during the process to ensure consistent and stable polishing performance. [Display omitted] • Alkaline elements in soda lime and borosilicate glass increased the slurry pH during the polishing process. • The nano-sized ceria slurry maintained its initial properties throughout the polishing of all glasses. • pH changes during polishing influenced the zeta potential and particle size distribution of ceria abrasives. • The highly aggregated particles, as indicated by our measurements, precipitate completely after a shorter time. [ABSTRACT FROM AUTHOR]

Knowing the influence mechanisms of fibers on ECC slurry fluidity and implementing the prediction of ECC slurry fluidity attach vital significance to the design and application of ECC. Based on traditional water film thickness (WFT) theories, this paper introduces the difference in surface WFT of reactive fibers and binding material particles with excess water distribution coefficient and further gives a modified formula for water film calculation and a WFT based ECC fluidity model. Through 40 tests and fitting, the excess water distribution coefficient with respect to distinct fibers and relevant parameters of the ECC fluidity model are obtained. The results indicate that the new model is applicable to different types of fibers, and the fluidity of ECC slurry can be described using an equation, with the R2 of the new equation reaching 0.97. Finally, based on the proposed model, the impact of PP and PVA fibers on the fluidity of ECC slurry can be summarized in two aspects: the wedge effect of the fibers reduces the packing density of the ECC powder, leading to a decrease in the excess water ratio; the water distribution in the ECC slurry is altered by the fibers, resulting in a decrease in the water film thickness on the surface of the cementitious material particles, ultimately causing a decline in the fluidity of the ECC slurry. [Display omitted] • The coefficient α is proposed to describe the influence of fibers on the water distribution state in ECC slurry. • A new WFT calculation model has been proposed, WFT s = U w ′ β s ∙ A s + α ∙ β f ∙ A f . • The relation between the fluidity of ECC slurry and WFT can be expressed by F = a WFT s + b. [ABSTRACT FROM AUTHOR]

The slump test can determine the yield stress of slurries by measuring the slump height. The convex shape in the slumped slurry profile cannot be characterised by the Tresca criterion. Lubrication theory has been widely applied to analyse the slow flow of yield stress fluids. Thus, the present study incorporates lubrication theory and the Tresca criterion to establish a generalized model for reconstructing the slurry profile based on the yield stress. The convex profile in the lower zone can be well represented by the novel method. The predicted yield stresses by the slump tests are larger than those determined using the vane method. Slump height and spread are equally accurate for predicting yield stress via the proposed method. Overall, the combination of lubrication theory and Tresca criterion yields a good prediction of yield stress based on slump height. [Display omitted] • A prediction model of slumped slurry profile is proposed. • Lubrication theory can characterise the convex shape of slurry profile. • Lubrication theory predicts a larger yield stress than the vane method. [ABSTRACT FROM AUTHOR]

This study introduces the application of a spiral structure in pipeline transportation to enhance the pipeline capacity of a slurry shield circulation system. A numerical model of solid–fluid coupling in a pipeline with a double spiral structure was established based on computational fluid dynamics and the discrete element method (CFD–DEM) theory, and its validity was confirmed through comparison with experimental data. The characteristics of the spiral pipeline were evaluated by comparing them with those of a conventional smooth straight pipeline. A multi-objective optimization method for determining the structural parameters of a spiral pipeline in a slurry shield circulation system is proposed using the Kriging surrogate model. The optimized design of a spiral pipeline was demonstrated through a specific project, and the impact of the main structural parameters on the slurry transport characteristics of the pipeline was analyzed. The results indicated that the optimized structural parameters led to an 18.65% increase in the average flow rate of the slurry and a 19.13% reduction in the accumulation of stones in the pipeline. [Display omitted] • The Spiral pipeline with transverse protrusion is applied to slurry-water circulation pipe. • The slag carrying performance of pipeline was evaluated by CFD–DEM method. • The relationship between the structure parameters and the slag carrying performance of the pipeline is studied. • The optimization process is used to optimize the structural parameters. [ABSTRACT FROM AUTHOR]

Coral reef limestone is a highly fossiliferous and porous sedimentary rock, ubiquitous in continental shelves and deep oceanic zones. To understand the slurry infiltration process from a microscopic perspective, we use X-ray computed tomography (CT) to reconstruct the complex three-dimensional pore structures of a coral reef limestone sample and further perform CFD-DEM simulations to capture the transport behavior of slurry particles passing through the reef limestone skeleton. The simulation results show that the kinetic energy of slurry particles in general follows a linear relationship with the applied pressure differential, which is influenced by the physical characteristics of pore channels. The particle infiltration time is inversely correlated to the pressure differential obeying a power-law function. In addition, statistical analysis of the length and spatial distribution of particle trajectories indicates the dominant role of high-coordination-number pore spaces in slurry suspension infiltration through the reef limestone. Our results have important implications for slurry shield tunneling through coral reef limestone strata. [Display omitted] • Detailed pore structure of a coral reef limestone was constructed from CT images. • CFD-DEM simulations were performed based on the constructed pore structure. • Both single particle and slurry suspension infiltration processes were simulated. • Length and spatial distribution of slurry particles' trajectories were obtained. • The key pore nodes for slurry infiltration were identified. [ABSTRACT FROM AUTHOR]

This study aimed to solve the problem of clogging in the working chamber of a large-diameter slurry shield passing through the clay stratum. Numerical simulation and experimental methods were employed to investigate the migration behavior of the muck in the original working chamber structure. The impact of increasing the percentage of scouring flow and implementing the suction port extending forward method on the muck discharge performance was also investigated. The results indicated that raising the scouring flow percentage could not improve the muck discharge performance under the original structure. However, extending the suction port to 500 mm from the slurry gate resulted in a 75.19% increase in the muck discharge rate and an 84.70% reduction in muck accumulation at the bottom of the chamber. Moreover, closing the scouring pipelines V25 and V7 after extending the suction port forward allowed for more efficient use of the limited slurry flow. Finally, an optimized suction port extending forward method was proposed and successfully applied to alleviate the clogging issue. [Display omitted] • The muck migration behavior was analyzed by the CFD-DEM method in the slurry shield • The suction port extending forward method can alleviate the working chamber clogging • An optimized suction port extending forward scheme was proposed and applied • The prototype slurry shield's advance speed and muck discharge were improved [ABSTRACT FROM AUTHOR]

In this study, we develop a three-dimensional computational model to explore the transportation and thermal characteristics of a bi-modal slurry flowing through a horizontally placed 90° pipe bend. The slurry comprises silica sand (SS) and fly ash (FA) granular, with varying combinations (65:35, 75:25, 85:15, 95:05, and 100:0). The computational investigation has been carried out for different carrier fluid's characteristics, including Prandtl number, and flow velocity (5 m/s), for efflux concentrations of C w = 40–60% for each mixture. Validated with experimental data, the computational approach employs a two-phase Eulerian-Eulerian RNG k-ε turbulence model and the kinetic theory of granular flow. Results reveal that the 65:35 combination exhibits minimal pressure drop, and the 100:0 combination shows maximum heat transfer characteristics, particularly with low-viscosity fluid (Pr = 2.88) and high particle efflux concentration (C w = 60%). The study also examines bend loss coefficients (K t) , concentration distribution, convective heat transfer coefficient (h), and Nusselt number (Nu) across different Prandtl fluids and efflux concentrations. [Display omitted] • 3D CFD modeling of bi-model slurry flow via horizontal 90° bend pipe is investigated. • Effect of different slurry mixture combinations on slurry flow characteristics is studied. • Slurry with 65:35 combination at efflux concentrations shows maximum efficiency. • Transportation of slurry with higher Pr demonstrates lower heat transfer coefficient. • Pressure drop, heat transfer coefficient and Nusselt number increases with C w. [ABSTRACT FROM AUTHOR]

During the pipeline transportation of backfill slurry, flow velocity has direct effects on the transport properties and then influences pipe blockage and wear. In this paper, a novel flow loop-horizontal electrical resistivity (HER) test system and Eulerian model were used to investigate the flow behavior and HER characteristic of cemented coal gangue-fly ash backfill (CGFB) slurry under different flow velocity. The results showed that: 1) The pressure drop of CGFB slurry increased linearly with flow rate. 2) The increase in flow rate significantly reduced coarse aggregate contents near the bottom of the pipeline. 3) As the flow rate increases, the fluctuation of measured HER with time increased, the HER differences decreased, and the ranges of the high and low resistance area at the bottom and top of the pipeline, respectively, kept decreasing. The results can provide guidance for HER monitoring of flow state of CGFB slurry in pipeline. [Display omitted] • Flow loop tests were implemented to study the pressure drop of CGFB slurry. • The dynamic ER of CGFB slurry during the pipeline transportation was investigated. • The pipe flow behaviors of CGFB slurry were studied using CFD method. • The relationship between the ER and coarse aggregate content was established. • Effects of flow velocity on ER distributions was analyzed. [ABSTRACT FROM AUTHOR]

In chemical mechanical planarization (CMP), a particle slurry is used in polishing semiconductor wafers. Key to CMP performance is the size distribution of the particles. We evaluate the potential of an aerosol technique, namely differential mobility analysis (in a liquid nanoparticle sizer, LNS, system) to characterize size distributions of CMP slurries. LNS measurements are compared to size distributions inferred from electron microscopy (SEM), and dynamic light scattering (DLS). LNS measurements are more repeatable than DLS measurements, and for 4 silica slurries, LNS distributions are in better agreement with SEM measurements than DLS. We find also that the LNS can quantify multimodal size distributions. For non-silica slurries, LNS, DLS, and SEM measurements have geometric mean diameters which can vary from another by 10 nm or more. However, because each measurement type is internally consistent, the combination of LNS and DLS, which are automated, yields augmented information on slurry properties. [Display omitted] • The size distribution of CMP slurries affects their performance. • We evaluate aerosol based approaches for CMP slurry size measurements in comparison to EM and DLS. • Aerosol measurements accurately measure multimodal distributions. • For metal oxide particles, aerosol measurements compliment DLS measurements. [ABSTRACT FROM AUTHOR]

This study evaluates and quantifies fracture roughness effects on proppant particle settling in fractures utilizing coupled, resolved computational fluid dynamics (i.e., simulation of carrier fluid behavior) and the discrete element method (i.e., simulation of proppant particle behavior). This work focuses specifically on "slickwater" based proppant slurries. Rough fracture geometries are generated using a spectral-based algorithm with surficial roughness varied by adjusting fractal dimension and root-mean-square asperity heights descriptive parameters. This work also considers particle volumetric concentration and influence from flowing conditions on particle settling. Results indicate that the attenuation of quiescent settling rates is more pronounced in rough fractures as the aperture narrows. The degree of quiescent slurry settling attenuation corresponds to fractal dimension and root-mean-square asperity height values. A formulation to describe the average settling rate of quiescently settling slurries in rough fractures is proposed and evaluated. Fracture roughness causes erratic settling velocities of flowing slurries, with some cases having upward proppant velocity, specifically at narrow apertures at or below two times the particle size for the condtions considered in this work. The onset of this behavior is dependent on degree of roughness, with erratic velocities occurring at narrower relative apertures for smoother fractures compared to rougher fractures. Preferential flow pathways formed in rough fractures at narrower apertures, are noted to cause these erratic settling behaviors. The overall findings provide a greater understanding of particle settling behavior in rough rock fractures, aiding in the design process for fracture enhancement projects. [Display omitted] • Slurry settling in rough fractures attenuated due to increased physical interaction. • Quiescent slurry settling in rough fractures attenuation factor proposed. • Rough fracture surfaces can cause high variability in particle settling rates. • Flow rate may impact particle settling when confined in narrow slots. [ABSTRACT FROM AUTHOR]

As a raw material, applications of waste activated carbon (WAC) in synergy with coal powder to prepare coal water slurry (CWS) and perform high-temperature gasification is a novel strategy for disposing WAC. Combining BET surface analysis, contact angle measurement, and thermogravimetric-Fourier transform infrared (TG-FTIR) methods, the physico-chemical properties and CO 2 gasification behaviors of coal-waste activated carbon-slurry (CWACS) were evaluated. Compared to coal, WAC exhibited an excellent adsorption capacity and a stronger surface wettability. When the WAC mixing ratio was increased from 0 to 15%, the CWS solid concentration decreased from 62.28% to 59.44%. CWACS exhibited a shear-thinning flow behavior, and the higher the WAC mixing ratio, the more obvious the pseudoplastic characteristics. Moreover, WAC enhanced the storage stability of the CWS. Under the catalysis of Na, Ca, and Fe among others, the CO 2 gasification reaction of CWACS coke moved forward to the low-temperature stage. The high fixed carbon content of WAC, as well as its unique tar adsorption and catalytic cracking effects, increased the CO gas component in the synthesis gas. [Display omitted] • Rich pores and strong wettability were features of waste activated carbon powder. • Pseudoplastic characteristics of slurry became more obvious with the blending. • Waste activated carbon powder enhanced the storage stabilities. • Waste activated carbon reduced the tar output and increased the effective syngas. [ABSTRACT FROM AUTHOR]

Particle transport in a vertical nonplanar fracture is a typical but poorly understood element in hydraulic fracturing. Particle-fluid flow in a nonplanar fracture with a narrowing width is investigated experimentally by a laboratory-scale slot, and the relevant transport mechanisms are compared with that in the planar slot. The effects of fluid flow rate, particle density, particle size, and particle volume fraction on particle distribution are investigated. The results indicate that the narrowing width complicates the slurry flow and lowers the bed coverage area. The vortex flow appears at the contraction of the cross-section as the bed grows to a threshold height and resuspends more particles further into the slot. An irregular bed with a descending stepped surface is formed due to non-uniform placement. Smaller size sands injected at a high flow rate and a low particle volume fraction build up a smaller bed. Larger and denser particles would reverse the trend. A rational model expressed by four dimensionless numbers is developed by the linear regression method to predict the coverage percentage of the particle bed. The model and experimental results provide directions to quantitatively evaluate the particle transport and distribution in a nonplanar fracture. [Display omitted] • The particle transport in a nonplanar fracture with a narrowing width is investigated by the experiment. • The dimensionless parameters are used to describe the particle distribution in nonplanar fractures. • The irregular bed with a descending stepped surface is smaller than the regular bed in the planar slot. • A correlation is developed for predicting the coverage percentage of the particle bed. [ABSTRACT FROM AUTHOR]

A novel CaCO 3 nanoparticle modification method by a styrene-acrylic polymer emulsion (SAPE) was introduced. The self-made SAPE was sprayed into the nano-CaCO 3 slurry system, and SAPE chains were encapsulated onto the CaCO 3 nanoparticle surface. The modified CaCO 3 nanoparticle mechanism was discussed. Fourier transform infrared spectroscopy confirmed that the SAPE chain was anchored on the nano-CaCO 3 surface by the reaction of the SAPE carboxyl group with the hydroxyl group on the CaCO 3. The effect of acrylic acid (AA) amount on the activation degree and oil absorption of CaCO 3 /SAPE composite nanoparticles was investigated. The amount of AA was 2%, and the activation degree and oil absorption of the product were optimal. The estimated grafting efficiency of the CaCO 3 /SAPE composite nanoparticles was 90.5% when the amount of acrylamide (AAM) was 1.5%. Scanning electron microscopy showed that the CaCO 3 nanoparticles could be dispersed uniformly in polypropylene (PP) film and formed a closed integration by SAPE-modified CaCO 3. The styrene-acrylic polymer chains that were grafted on the CaCO 3 nanoparticle surface could improve the compatibility between the CaCO 3 nanoparticles and PP matrix. The PP composite film with modified CaCO 3 nanoparticles had a higher tensile strength than that of pure CaCO 3 nanoparticles, which can improve the mechanical properties of the PP material. [Display omitted] • Surface modification of CaCO 3 nanoparticles was performed by a unique process. • The modified CaCO 3 nanoparticle mechanism was elaborated. • The PP with CaCO 3 /SAPE has a higher tensile strength than that of pure CaCO 3. [ABSTRACT FROM AUTHOR]

Aims at improving the utilization rate of red mud and preparing a low-cost grouting material for underground engineering, the ultrafine red mud was adopted to prepare a slag-red mud based grout, and its fresh and hardened state properties were investigated comparing with the coarse red mud. The results showed that the incorporation of red mud could prolong the setting time and decrease the viscosity and thixotropy of slag-based geopolymeric grout, and ultrafine red mud has a better decrement effect. Ultrafine red mud has an enhancement effect on the slurry stability. The mechanical strength decreased with the adoption of red mud, while the ultrafine red mud has a higher mechanical strength than coarse red mud. The microstructure analysis showed that red mud plays a filling role in the geopolymerization process, and mechanical activation could increase the reactivity of red mud, furthermore, the iron component in ultrafine red mud could take part in the geopolymerization process. The results shed light on the utilization of red mud and the application of geopolymer in grouting engineering. [Display omitted] • A grouting material was prepared by ultrafine red mud and blast-furnace slag. • Workability of slag-ultrafine red mud based grout was investigated. • Mechanism of mechanical activation was revealed by microstructure analysis. [ABSTRACT FROM AUTHOR]

In the present study, the thickening process of tailings slurry in a gravity thickener is modelled using Computational Fluid Dynamics (CFD), with a focus on the effects of particle size and feed velocity. A Two-Fluid Model (TFM) is employed to describe the particle-fluid and particle-particle interactions while turbulence is described by the ω -based Reynolds Stress Model (RSM). The validity of the model is demonstrated by close agreement between experimental measurement and simulation predictions of total solid mass of underflow, and particle cumulative mass distribution as a function of particle size in the underflow. The feedwell performance is evaluated in terms of kinetic energy dissipation and mixing performance. Particle size has a significant influence on the distribution of solid concentration. The increase of particle size leads to a higher critical settling height. For a given underflow discharging rate, solid concentration in the underflow increases with feed velocity only in a certain range, whereas increases continuously in the overflow. Large particle size corresponds to a higher critical feed velocity. Modelling the granular flow with a wide particle size distribution in a thickener helps explore the particle dynamic behaviors, thereby improving the thickening process. [Display omitted] • The liquid-solid flow in a gravity thickener is modelled by a Two-Fluid Model (TFM). • The feedwell is evaluated by kinetic energy dissipation and mixing performance. • Particle collisions are modelled by employing the kinetic theory of granular flow model. • The effects of particle size and feed velocity on thickening performance are explored. [ABSTRACT FROM AUTHOR]

Gravity thickening by deep cone thickener is popularly applied in cemented paste backfill, which is essential for tailings management and green mining. To avoid rake bogging, high concentration and high flowability are required for thickened tailings slurry. These properties depend critically on the yield stress of the slurry. The yield stress, in turn, can be influenced by the flocculant dosage and the acidity (pH) that form the flocculation condition. Experiments have been performed to eventually quantify the dependence of yield stress on these two variables. The yield stress test of flocculated and thickened copper mineral tailings slurry, and the analysis of flocculant adsorption, were conducted at different pH values and flocculant dosages. It turns out that the amount of flocculant adsorbed on the tailings particles surface has a maximum with respect to pH but increases with the increasing flocculant dosage. In turn, the amount of flocculant adsorbed affects the yield stress, a macroscopic property of the slurry, through the total interactions (microscopic) between polymer-coated tailings particles. Bridging interaction is essential for total interactions. It is obtained that the yield stress varies analogously to the absolute of the minimum value of the total interactions at different pH values and flocculant dosages. Therefore, interparticle interactions should be adjusted by control pH and flocculant dosage to achieve high-concentration and high-flowability underflow to avoid rake bogging in a deep cone thickener. [Display omitted] • The relationship between interparticle interactions and yield stress was investigated. • Bridging interaction is essential for interactions between polymer-coated particles. • Flocculant dosage has a significant influence on the yield stress of thickened tailings slurry. • pH and flocculant dosage affect flocculant adsorption and interparticle interaction. [ABSTRACT FROM AUTHOR]

Ultrasonic attenuation spectroscopy (UAS) has many advantages in online in-process characterization of particle size distribution (PSD) in slurries. It can be applied to systems with relatively high solid concentration and wide particle size range from nanometres to millimetres sized particles. The model used by a UAS instrument to estimate the PSD from an attenuation spectrum requires some physical properties of both the liquid and solid phases to be known. For instance, the most popular UAS model, the Epstein–Carhart and Allegra–Hawley (ECAH) model, requires fourteen physical properties. Therefore, applications where all or some of the required physical properties are unknown or difficult to measure, such as crystallization, pose a major challenge to its use. In this work, a procedure for estimating the unknown physical properties is proposed. This is done by iteratively learning the unknown physical properties to minimise the difference between the measured attenuation spectra and that predicted by the ECAH model. One of the main challenges of this procedure is the presence of multiple local minima but these can be eliminated by a combination of a global optimisation algorithm, the use of multiple particle size distributions and solid concentrations. The procedure was validated using Silica and Titania standard reference materials, and applied to the estimation of the relevant physical properties of saturated aqueous solution of SrCl 2.6H 2 O and Sr(OH) 2.8H 2 O. The properties thus obtained was used for acoustic monitoring of the real-time evolution of PSD during the batch cooling crystallization of SrCl 2.6H 2 O in water. [Display omitted] • A learning method is presented for estimation of physical properties in applying acoustic sensor for particle size measurement. • It iteratively learns the physical properties to minimise the error between the measured and instrument model predicted spectra. • The method was validated using Silica and Titania standard reference materials. • It is also applied to SrCl 2.6H 2 O and Sr(OH) 2.8H 2 O cooling crystallization. [ABSTRACT FROM AUTHOR]

The major purpose of this investigation was aimed at assessing the mixing capability of a coaxial system comprised of a central pitched blade impeller with a high rotating speed and a wall scrapping outer anchor with a low rotating speed in suspending highly concentrated slurries using flow visualization (electrical resistance tomography) and numerical (computational fluid dynamics) techniques. The 2D images acquired by tomography and simulation methodologies were utilized in creating solid concentration profiles. Different mixing indexes were employed to analyze the impacts of solids concentration gradients on the solids distribution. The effects of different factors namely solid concentration, average particle size, speed ratio, anchor speed, rotating mode, and solid specific gravity on the suspension and dispersion quality was analyzed. The results clearly revealed that the coaxial mixer provided better suspension quality at lower power utilization compared to that achieved by a single central impeller in dense suspension systems. [Display omitted] • Tomography and CFD were used to assess the suspension of highly concentrated slurries. • The assessment of the optimum rotational speed of the outer anchor was paramount. • The maximum achievable homogeneity decreased with an increase in the solid loading. • Co -rotating mode was more effective than counter-rotating mode in mixing of slurries. • The coaxial mixer was highly efficient in mixing of highly concentrated slurries. [ABSTRACT FROM AUTHOR]

Magnesium phosphate cement (MPC) has been applied in grouting engineering due to its features of quick setting, high early-strength, and perfect volume stability. The rheological properties (RPs) of MPC, being vitally important for site operation, need to be studied further. Sodium tripolyphosphate (STP) is one type of high-efficiency retarders used in MPC. This study investigated the effects of STP content on the RPs of MPC pastes, and the mechanisms were studied by characterizing the zeta potential, 1H NMR relaxation signal, water film thickness, mineral changes, and electrical impedance. Experimental results indicate that the plastic viscosity (η) increases gradually and the yield stress (τ 0) decreases firstly and then increases with increasing the STP content. The influencing mechanisms of STP need to be distinguished by analyzing η and τ 0 respectively. The water film thickness and the amount of intermediate hydration products within 15 min of hydration is directly related to the change in η. The porosity and distribution of free water obtained from 1H NMR in MPC slurry are the dominant factor for τ 0 , and followed by the diffused double layer. It is noteworthy that zeta potential is not an effective measure for studying the RPs of MPC. Results of electrical impedance also explain the mechanisms of STP retarding the hydration and improving the early-term strength of MPC. [Display omitted] • Effects of STP on the yield stress and plastic viscosity of MPC paste are not consistent. • Plastic viscosity is affected by the water film thickness and amount of intermediate hydration products. • The porosity and distribution of free water is the dominant factor for the yield stress. • Mechanism of STP delaying the hydration and improving the early strength was proposed in detail. [ABSTRACT FROM AUTHOR]

Metakaolin (MK) and silica fume (SF) have been added either individually or in combination to improve concrete performance. Recent studies proved that the combined addition of MK and SF offers synergistic effects, but the mechanism behind is still not unclear. Herein, it is postulated that the synergistic effects arise mainly from the successive filling effects of the MK and SF into voids between larger size particles, which increase the wet packing density (WPD). The present work indicated that the slurry formed of the water and ultrafine particles plays an important role. Good correlation of the workability measures to the slurry film thickness (SFT) revealed the governing factor of SFT for the first time. Moreover, the synergistic effects of MK and SF on the compressive and flexural strengths have been studied based on cementing efficiency and synergistic factors. Correlation of the synergistic factor to the WPD revealed that the WPD plays an important role. [Display omitted] • The simultaneous use of metakaolin and silica fume is explored. • The concept of slurry film thickness is established for modeling. • Formulas based on slurry film thickness are derived for workability. • Synergistic factor and particle packing are associated with strengths. [ABSTRACT FROM AUTHOR]

The secondary circulation in a spiral concentrator had been explained in an earlier publication with the help of classical solid mechanics. In the present paper, classical solid mechanics has again been applied to develop simplified flow equations for fluid and slurry systems specific to the spiral concentrator. A new concept of composite coefficient of friction has been introduced for the slurry system, which considers the solids concentration and friction between layers of water. The flow equation can predict flow velocity with the number of turns and radial distance in spiral concentrators. Simulation studies on the proposed acceleration and velocity equations have been performed, which align with the general fluid flow behavior observed in spiral concentrators. A comparison of the velocities calculated with the proposed equation has been drawn with the corrected plot of equilibrium velocity, which further supports the presented equations. [Display omitted] • Fluid flow in spiral from velocity perspective. • A novel concept of composite coefficient of friction for slurry. • Development of flow equations for fluid and slurry. • Simulation of acceleration with radial distance. • Simulation study on proposed velocity equation. [ABSTRACT FROM AUTHOR]

Waste tire pyrolysis residue (WTPR) is a solid byproduct with high carbon content. Herein, WTPR was utilized in the preparation of WTPR water slurry (WTPRWS) to achieve resource utilization. Three dispersants (sodium ligninsulfonate [SL], hexadecyltrimethylammonium chloride [CTAC], and NP-40 substitute octylphenoxypolyethoxyethanol [NP-40]) were used in slurry preparation to improve the performance of WTPRWS. Results showed that the surface prpperties of WTPR had changed after dispersant adsorption through the analyses of FTIR, SEM–EDS, and XPS. The Langmuir equation was highly applicable for fitting the adsorption kinetics of the dispersants, and the adsorption quantity of NP40 was greater. NP40 exhibited better viscosity-reducing and stabilizing abilities in WTPRWS than the other dispersants. Meanwhile, shear-thinning characteristics were exhibited by all samples, especially the NP40 WTPRWS sample, which had the smallest yield stress. Moreover, the wetting properties and zeta potentials of WTPR before and after dispersant adsorption were analyzed. [Display omitted] • Three dispersants were used to prepare slurry fuel from waste tire pyrolysis residue. • The surface properties of WTPR had changed after adsorption of dispersants. • The adsorption isotherms of dispersants were well described by Langmuir equation. • The NP40 exhibited the better ability in improving the performances of WTPRWS. [ABSTRACT FROM AUTHOR]

[Display omitted] In this paper, the experimental results indicated that the hydrostatic pressure descent (HPD) curves of cement slurry include a stabilization stage, slow descent stage, and rapid descent stage. In the stabilization stage, the gravity of the solid particles dispersed in pore water was effectively transferred by the pore water. In the slow descent stage, the microstructure of cement slurry changed from "dispersed particles" to "gel network", causing the gravity of the particles to be diverted to external interfaces. In the rapid descent stage, hydrostatic pressure of the cement slurries was attributed to the pore water. But the rapid reduction in the pore size increased the capillary pressure of the pore water, causing the gravity of pore water to transfer to external interfaces via the "gel network". Finally, when the most probable pore diameter decreased to approximately 50 nm, the hydrostatic pressure of the cement slurry was reduced to zero. • This paper investigated the microstructure evolution of the cement particles. • A quantitative method was developed to test the pore structure of cement slurry. • The pore structure evolution of the cement slurry in the early stage of hydration was studied. • Three-dimensional pores of the cement slurry was obtained. • Combining the microstructure and pore structure, hydrostatic pressure descent mechanism of cement slurry was analysed. [ABSTRACT FROM AUTHOR]

Zirconia microspheres with high sphericity and hardness were successfully massively produced through a cost-effective spray granulation method by using an optimized slurry with high solid content and low viscosity which was formulated with a mixed dispersant. The influence of slurry solid content, binder addition as well as drying temperature on the shape and size of the sintered microspheres were studied. Furthermore, the formation mechanism of different granulated particles was analyzed based on the illustrated migration processes in the ZrO 2 droplets with different contents of water and additives. Under the optimized conditions, the sintered ZrO 2 spheres with tetragonal phase exhibit high sphericity with highest nano-hardness of 9.5 GPa, indicating it is possible to be used in the engineering fields. Such spray granulation method could directly serve for the industrial production of zirconia and other ceramic materials since it is a stable process with high yield, good granulating quality and strong controllability. [Display omitted] • ZrO 2 microspheres with high sphericity have been produced by spray granulation. • ZrO 2 slurry with high solid content and low viscosity has been obtained. • The formation mechanism of particles with different shapes has been demonstrated. • The sintered ZrO 2 microspheres can achieve a high nano hardness of 9.5 GPa. [ABSTRACT FROM AUTHOR]

Process analytical technology (PAT) plays a crucial role in optimizing crystalline powder product qualities, improving process stability, and reducing experimental costs by enabling real-time monitoring and control of process variables during the crystallization process. In-situ process imaging and analysis have gained significant attention due to their capacity to provide abundant information through images, leading to remarkable advancements in image processing technology, particularly with the support of artificial intelligence. However, the performance suffers when processing high-density slurry images due to challenges such as defocusing, overlapping, background and crystal edges blurriness, and inconsistencies in crystal scales. To address these challenges and explore research strategies based on deep learning for segmenting and analyzing high slurry density images effectively, this study constructed a specific dataset that contains high-density slurry crystal images which is well-labeled, and introduced state-of-the-art neural networks including YOLOv8, U2-net, and Mask R-CNN combined with image and data enhancement strategies. Comparative analysis revealed that YOLOv8 outperformed Mask R-CNN and U2-net by capturing multi-dimensional information in high-density crystal slurry scenarios. Finally, based on the segmentation results of the practical taurine crystallization process using proposed strategy, 1D crystal size, aspect ratio along with 2D size distributions were extracted for further evaluation of crystallization kinetics and crystal properties accurately and quickly. [Display omitted] • In-situ crystal micrograph of high slurry density image database was conducted. • The state-of-the-art networks were introduced to high-density scenarios. • High-density images were segmented in higher accuracy. • Multi-dimensional information was extracted more accurately using proposed deep-learning strategy. [ABSTRACT FROM AUTHOR]

Spray-drying granulation has been widely used to produce granules with good flowability due to its attractive features of low cost, high efficiency, and mass-production. In the present study, Cr 2 AlC MAX phase microspheres with particle sizes of 30–70 μm have been successfully prepared by spray-drying granulation. The main influencing factors of solid content in slurry and atomizer frequency on sphericity, size, and apparent and tap densities of spray-dried Cr 2 AlC microspheres were investigated under constant pumping pressure and drying temperature. By optimization of spray-drying conditions, Cr 2 AlC microspheres with good sphericity, flowability, and apparent and tap densities were achieved from a slurry with a solid content of 60 wt% at an atomization frequency of 280 Hz. It was found that atomization frequency and solid content in slurry influence the flowability of microspheres, while the solid content plays a major role in improving the apparent density and tap density. The microstructure and phase composition of Cr 2 AlC microspheres was characterized. The spray-dried Cr 2 AlC microspheres are promising feedstock powders for preparation of high-quality cold-sprayed Cr 2 AlC coatings. [Display omitted] • Cr 2 AlC MAX phase microspheres has been achieved by spray granulation. • Effects of solid content and atomizer frequency on the quality of microspheres were confirmed. • Cr 2 AlC microspheres with sizes of 30–70 μm have better sphericity and flowability. [ABSTRACT FROM AUTHOR]

In this research, we used a high-speed video-recording system to experimentally study the surface transformation of droplets of water and water-based slurries, solutions, and emulsions exposed to the incoming air flow. The experimental parameters were varied in the following ranges: 0.3–3 mm for the initial droplet radius; 0.5–50 m/s for the air flow velocity; 10 vol% for the relative volume concentration of liquid additives to water; 10 wt% for the relative mass fraction of solid particles to water; 80–140 μm for the size of solid particles; 5–50 °C for the droplet temperature. Three regimes were identified: surface transformation without breakup; taking the bag shape followed by destruction; breakup into a cloud of small droplets. The novelty of the research lies in the maximum ratios of child droplet surface areas to the parent droplet surface area determined for the conditions typical of liquid discharge from various heights for fire suppression. [Display omitted] • The number of emerging child droplets and their total surface area were determined. • Three atomization regimes are singled out for droplets of liquids, solutions, emulsions, and slurries. • Surface tension, viscosity, and particle size of fire suppressants affects droplet transformation. • Droplet temperature is shown to have a significant impact on atomization characteristics. • The original size of droplets and solid inclusions in slurries affect the atomization characteristics. [ABSTRACT FROM AUTHOR]

Screen methods are time-saving tools, assisting the establishment of a new process or technique for laboratory and industrial scale. This paper presents a step-by-step approach to use spray drying (SD) for obtaining hydroxyapatite (HA) powder, with suitable characteristics to be used as a filler in a polymer matrix, for selective laser sintering (SLS) processing. The proposed method consists of adjusting the departing HA suspension and SD processing parameters, briefly discussing relevant elements that must be considered. Suspension's rheological behavior and spray-dried powder morphological features were investigated, serving as selection criteria for the favorable set-up. Variations on slurry feed and atomization pressure of SD processing parameters have allowed obtaining different powder characteristics. A major influence of atomization pressure variation was identified, a greater pressure value resulted in smaller particle size. Desirability function was employed to determine the optimal SD processing parameters, in other words, conditions that made it possible to obtain spherical particles with the proposed mean diameter in the range of 15 to 25 μm, with narrow particle size distribution. [Display omitted] • Spray drying technique was used to obtain spherical hydroxyapatite particles. • A step-by-step approach is proposed to obtain selective laser sintering feedstock. • Binder content has significant influence on spray dried particles. • Variation of spray drying processing parameters affects particle size distribution. • Spray dried particles in the range of 15 to 25 μm were obtained. [ABSTRACT FROM AUTHOR]

Fine grinding in wet stirred media mills is a key operation in numerous industrial processes. During wet milling, grinding beads (typically millimetre scale) collide with each other under rapid agitation. These collisions transfer energy into the surrounding medium, a feed stream comprising a premixed slurry (a suspension of micron-sized particles), leading to a reduced particle size. Numerical simulation provides an opportunity to gain mechanistic insight by modelling the influences of grinding media, agitator speed and slurry rheology on the breakage. The multiphase nature of wet milling necessitates models that account for both the solid grinding beads and the slurry feed. Established fluid-particle coupled methods are in principle capable of doing this, but the need to resolve the large hydrodynamic lubrication forces between near-contacting beads demands extremely high fluid field resolution, leading to proliferating simulation size and cost. To address this challenge, a Discrete Element Method (DEM) simulation for a lab scale mill is presented in which the bead-bead interaction includes pairwise hydrodynamic lubrication in addition to frictional contact forces. The model accounts for multiphase effects in a simplified yet physically well-motivated way, circumventing the computational cost of a fully fluid-resolved model. A systematic model calibration against the laboratory mill is presented, and thereafter the model provides a good estimation for the empirical power draw across the full range of rotation speeds and considered feed viscosities. The differences in energy dissipation modes and the local distribution of collisions along the mill chamber are examined for the extreme viscosity condition, revealing that most energy dissipation is due to inter-particle forces acting tangentially (shearing and rolling) while highly energetic collisions (impact and torsion), relying on free flows and inter-bead mobility, are relatively unimportant. [Display omitted] • A DEM model with pairwise hydrodynamic lubrication in addition to frictional forces • Systematic model calibration against the lab mill at varying operation conditions • An internal gradient on the energy dissipation and the local distribution of collisions • Computational speed-up may be gained with this DEM formulation [ABSTRACT FROM AUTHOR]

This article describes slurry development for lithography-based additive manufacturing (AM) of cemented carbide components. Due to their superior material properties compared to steels, tungsten carbide‑cobalt hardmetals are an exciting material for manufacturing tools. AM technologies' geometric freedom makes it possible to design more efficient tools compared to other manufacturing techniques. These technologies are known as resource-efficient and sustainable processes. The material that is not required for manufacturing is re-used for the production of additional components. The high energy input in laser powder bed-based AM processes leads to strong grain growth and brittle phases, so the achievable mechanical properties are significantly limited. Lithography-based additive manufacturing shows high potential due to the manufacturing of a polymer-bound green body and a subsequent heat treatment. Tungsten carbide‑cobalt (88–12 wt%) slurries were developed with a solid content of 40 vol%, based on the resin's reactive components. Dispersants made it possible to increase the maximum processable volume fraction of solid particles. A thixotropic agent helped stabilize the slurry. Rheological investigations characterized these effects. The influence of the photoinitiator concentration and the volume fraction of tungsten carbide and cobalt particles on the curing depth was analyzed. Prepared slurries and manufactured multi-layered green bodies were evaluated for homogeneity using quantitative microstructure analysis. [Display omitted] • This article describes slurry development for lithography-based additive manufacturing of cemented carbide components. • The volume fraction was increased using dispersants and the slurry was stabilized using a thixotropic agent. • Curing behavior was investigated and multi-layered green bodies were manufactured. • Quantitative microstructure analysis was used to characterize the slurry and green bodies. [ABSTRACT FROM AUTHOR]

In this study, based on the idea of cutting particle packing from three to two dimensions, an indirect evaluation method for calculating packing voids and probabilities is proposed. Actual coal particles with average particle sizes of 244, 104, 45 and 17 μm were used to build 20 stable three-particle packing and 35 unstable four-particle packing models. Three algorithms, the Law of Cosines, Heron Formula, Bretschneider's Formula were used to calculate irregular particle packing voids. Four indexes of cumulative void areas, ƩPV T , ƩPS T , ƩPV Q and ƩPS Q (P is the probability, V T , S T , V Q , S Q are void areas both in three-particle and four-particle packing) were created. The accuracy of the method was testified by poly-nominal fit analysis. The correctness of this method was confirmed by two case studies of 96 factory CWS samples and 18 laboratory CWS samples. The method also provides a feasible way to evaluate particle packing in other industrial fields. Unlabelled Image • Three algorithms are proposed to calculate irregular particle packing voids. • Particle packing distribution is quantitatively described by probability analysis. • Indexes of ƩPV T , ƩPS T , ƩPV Q , ƩPS Q are created to evaluate packing efficiency. • Simplified particle packing from three dimensions to two dimensions. • Optional evaluation method with high fit analysis accuracy. [ABSTRACT FROM AUTHOR]

The performance of chemical mechanical polishing (CMP) was determined by the morphological characteristics of the abrasive particle. In this study, the shape of the aggregate of fumed silica was confirmed by a method of characterizing the morphology of the particles using transmission electron microscopy (TEM). Each aggregate was classified into four types—linear, branched, ellipsoidal, and spheroidal—and the shape distribution of a fumed-silica slurry was investigated with different specific surface areas. The CMP performance of fumed silica slurries at 90 m2/g with numerous linear-shaped aggregates and 400 m2/g with the highest portion of spheroidal aggregates were compared to that of colloidal silica slurry. A model for the effects of bumpy abrasives on CMP explained the reason for this result by using penetration depth and MRR with various numbers of contact bumps. Furthermore, a mixture of spherical and non-spherical abrasives in a ratio of 4:1 exhibited an improved CMP performance. Unlabelled Image • The material removal principle of differently shaped particles was analyzed. • A method for capturing a single aggregate in fumed silica slurry was introduced. • The shape distribution of particles differs depending on the specific surface area. • The polishing performance was enhanced by mixing abrasives of different shapes. [ABSTRACT FROM AUTHOR]

To obtain a cement paste with high alternate ultra-high temperature (AUHT) resistance, this paper investigated the effects of metakaolin and graphite on the properties of cement paste. The results demonstrate that in the AUHT curing process, the ultra-high temperature changed the tetrahedral silicate structure in C-S-H from chains (Q2) to isolated silicate (Q0) or a dimer group (Q1), damaging the microstructure of C-S-H. Meanwhile, the substantial temperature difference caused the volume of each hydration product in the cement paste to vary unevenly, giving rise to high internal stress in the cement paste and thereby reducing its mechanical properties. However, metakaolin improved the mechanical properties of the cement paste by the filling effect and pozzolanic reaction. In addition, the layered structure of graphite accommodated the uneven variation of each hydration product in the cement paste at AUHT, reducing the internal stress and improving the mechanical properties of the cement paste. Unlabelled Image • Focus on improving the alternate ultra-high temperature (AUHT) resistance of Portland cement pastes. • The influence of AUHT on the chemical structure and microstructure of C-S-H. • Graphite improve the structural integrity and mechanical properties of the cement slurry at AUHT. [ABSTRACT FROM AUTHOR]

Electrostatic separation can be used to remove micron-sized catalyst particles from fluid catalytic cracking (FCC) slurry. In this study, simulations were performed with experimental parameters. The distributions of the electric field, slurry flow and particle motion were studied. According to the particle movement characteristics, an effective adsorption region was found in which the particles would be adsorbed on the surface of the fillers. The effect of the effective adsorption region on the electrostatic removal of catalyst particles from the FCC slurry was discussed. The size of the effective adsorption region was inversely proportional to the voltage and ionic carrier concentration. Under the same parameters, the size of the effective adsorption area and the motion of the particles were compared between the experiment and the simulation. The results showed that the numerical simulation results were in good agreement with the experimental results. Unlabelled Image • This study mainly discusses the effect of effective adsorption area in the electrostatic adsorption of catalyst particles. • Both voltage and ionic carrier concentration have influence on the effective adsorption region. • Different adsorption effects of particles in different positions. • The research contents include numerical simulation and experimental verification. [ABSTRACT FROM AUTHOR]

MgO slurry become more and more important in wet desulfurization process because of high desulfurization activity and recyclable by-products. While the removal of SO 2 by micron-sized MgO slurry is limited due to particle size. Hence, micro-sized MgO slurry and MgO nanofluids of the same concentration were prepared. The stability of MgO nanofluids had been investigated. The density and viscosity of MgO nanofluids increased with the increase of concentration, but decreased as the temperature increase, and MgO nanofluids belong to Newtonian fluids. The evaluation of desulfurization effect and calculation of the mass transfer coefficient indicated that MgO nanofluids had better desulfurization effect compared with MgO slurry. The desulfurization efficiency increased with the increase of concentration, while the growth rate of desulfurization efficiency dropped sharply as the concentration exceed 4 wt%. Therefore, reducing the particle size properly can improve desulfurization efficiency of MgO absorbent in removal of SO 2 from flue gas. Unlabelled Image • MgO nanofluids were used in flue gas desulfurization. • Compared with MgO slurry, MgO nanofluid had better stability. • The removal efficiency of SO 2 increased as the particle size reduced to nanometer. • The mass transfer coefficient could be 2.302 mmol/(m2·s·kPa)−1 at 5 wt% nanofluids. [ABSTRACT FROM AUTHOR]

The main purpose in this study was to understand the interactions of coal particles with three amphiphilic humic acid-based polymers, which were designed and synthesized through the copolymerization of humic acid (HA) with maleic anhydride-polyethylene glycol 400 monoester, methacrylatoethyl trimethyl ammonium chloride or both of them, respectively, abbreviated as HAM, HAD and HMD. The adsorption quantities of HMD and HAD increased monotonically with the equilibrium concentration of dispersant, which were well described by Freundlich adsorption equation, but the Langmuir adsorption equation was more suitable for HAD dispersant. Besides, the wettability of HMD solutions on the coal surface was better than others. Moreover, the HMD dispersant exhibited better viscosity-reducing and stabilizing capability for coal-water slurry (CWS) than that of HAD and HAM, which were due to the strong adsorption force that was good for improving the hydrophily and enhancing the steric hindrance and electrostatic repulsion among coal particles. Unlabelled Image • Three humic acid-based dispersants were synthesized and used as dispersants for CWS. • The adsorption isotherms of HMD and HAD were well described by Freundlich equation. • The wettability of HMD solutions on the coal surface was better than others. • The HMD showed the better viscosity-reducing and stabilizing ability in CWS than others. • The excellent performances of HMD were due to strong adsorption and steric hindrance. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the vibration on the stability and settling performance of the coal water slurry (CWS) was systematically investigated using a Turbiscan Lab analyzer. The results showed that the vibration played an important role in affecting the particle motion and enhancing or deteriorating the stability of the CWS was largely dependent upon the vibration strength. The sedimentation analysis implied that the periodic and slight strike could facilitate the settling process of particles on the top and thus deteriorated the stability. However, the strong strike would induce serious particle collision, which could not only put an obstacle to the sedimentation process of particles on the top (i.e., enhancing the stability) but also facilitate the particles in the middle settling to the bottom (i.e., deteriorating the stability). The results can provide a fundamental basis for the understanding of the behavior of particles motion under the vibration conditions. Unlabelled Image • The vertical vibration was applied to study the dynamic stability of CWS. • Slight strike facilitated the settling process of particles on the top. • Strong strike induced serious particle collision. • The collision put an obstacle to the settling process of particles on the top. • Also, the collision facilitated particles in the middle settling to the bottom. [ABSTRACT FROM AUTHOR]

To improve the properties of cemented ultra-fine tailings backfill (CUTB), the authors intend to outline the framework of the effect of steel slag (SS) on the properties of CUTB. Therefore, flowability, unconfined compressive strength (UCS), hydration products, and pore structure were used to investigate the properties of CUTB samples. The results showed that the incorporation of SS increased the flow spread by increasing the water film thickness (WFT). Unconfined compressive strength (UCS) was observed to be enhanced when the content of SS did not exceed 20 wt%. Hydration phase evolution tested by X-ray diffraction, thermogravimetry, and thermodynamic modeling indicated the additional formation of hydrotalcite-like phases (Ht). This contributed to a denser microstructure. Besides, lower total porosity and critical pore diameter (dcr) obtained by mercury intrusion porosimeter tests were observed in samples with SS addition, which could favor the strength development. On the other hand, toxicity characteristic leaching procedure (TCLP) results indicated that the CUTB exhibited good environmental performance. Unlabelled Image • Adding SS increased the flowability of UCTB slurry through enhancing the WFT value. • The addition of SS increased the UCS of UCTB samples after curing for 28 days. • Incorporating SS reduced the C-S-H formation but increased the Ht generation. • Refined pore structure due to the addition of SS was observed. [ABSTRACT FROM AUTHOR]

Ice-containing cemented paste backfill (ICPB) is a novel type of backfill material that has both the advantages of traditional CPB and the underground cooling function. The pipeline transport characteristics of ICPB need to be investigated to promote its application, which are influenced by the rheological properties. The objective of this study is to investigate the rheological properties of ICPB by means of experimental and computational fluid dynamics (CFD) methods. The rheological parameters were measured using a rheometer and the slump test was performed in a cylinder slump. A calculation model that considered the slump mold lifting and the ice particle phase change was established to simulate the cylindrical slump. The results indicate that the ICPB behaved as a Bingham fluid. The yield stress, plastic viscosity, and thixotropy increased with an increase in the ice/water ratio and concentration, while the cylindrical slump decreased under the same variation. The simulation results of the cylindrical slump were compatible with the experimental results. Furthermore, the numerical study indicates the slump increased when the test temperature was increased from 285 K to 305 K. The results found in this study can be used as a reference for the pipe design of ICPB. Unlabelled Image • Rheological property of ice-containing cemented paste backfill (ICPB) was studied. • Lab experiments and computational fluid dynamics (CFD) simulations were used. • The relation of rheological property to ice and solid contents was discussed. • The CFD results had good agreements with the experimental ones. • The CFD results indicate the slump increased with a higher test temperature [ABSTRACT FROM AUTHOR]

Sludge from coal chemical industry is hazardous and difficult to disposal. In this study, a coal chemical sludge was mixed with lignite, coking coal and lean coal to prepare coal-sludge-slurry(CSS) for gasification and combustion. The results showed that the addition of sludge changed CSS from the dilatant fluid to the yield pseudo-plastic fluid. The stability of CSS was observed increasing, while the preparation concentration was decreased at the same viscosity requirement. A combination of BET analysis and EDLVO theory calculation was carried out to study the behavior among particles and water in CSS. Sludge could attract considerable water, increasing the viscosity of slurry. Besides, sludge might connect with coal particles to structure a three-dimensional network which would be destroyed by agitation and then released trapped water, resulting in the pseudo-plasticity of CSS. The network could also prevent the aggregation of particles and improve the stability of slurry. Unlabelled Image • Coal-sludge-slurry were prepared by three coals and sludge from coal liquefaction. • The addition of sludge made slurry more stable as TSI max decreased from 0.93 to 0.24. • Sludge made slurry more pseudo-plastic as fluidity index n reduced from 1.11 to 0.63. • Sludge connected with coal particles to form a network according to EDLVO calculation. [ABSTRACT FROM AUTHOR]

In the present work, experimental studies were conducted to examine the gas-slurry interfacial shear stress and frictional pressure drop in the presence and absence of surfactant in a rectangular slurry column. A novel mechanistic model has been proposed by considering the energy dissipation rate because of bubble formation, a slip of gas-slurry interface, and the wetting of a thin liquid layer with the column wall. A comprehensive investigation was carried out to enunciate the effect of particle loading, particle size, bubble size, and surfactant on the frictional pressure drop and bubble-slurry interfacial shear stress. Generalized empirical correlations were also developed based on the dynamic variables, geometric variables, and physical properties of the system. Unlabelled Image • Phenomena of frictional pressure is analyzed in a rectangular slurry bubble column. • Bubble-slurry interfacial shear stress is interpreted by a mechanistic model. • Physiochemical effect on bubble-slurry interfacial phenomena is explained. • Rate of energy dissipation by wetting phenomena is enunciated. • Bubble formation effect on interfacial friction factor is explained. [ABSTRACT FROM AUTHOR]

Particles play significant roles in the flow structure of gas-liquid flows in slurry bubble columns. The Dual-Bubble-Size (DBS) model based on the Energy-Minimization Multi-Scale (EMMS) approach has been developed to characterize gas-liquid flows by incorporating a stability condition in our previous work. A Particle-dependent Dual-Bubble-Size (PDBS) model is thereby developed in this work to analyze the different particle effects on gas-liquid flows. The particle effects on apparent properties of liquid phase and drag coefficients of bubbles are considered for systems of wettable particles. The model calculation indicates that the regime transition is delayed due to the increase of apparent density and viscosity. On the other hand, the particle effect on bubble drag coefficients decrease the gas holdup. The PDBS model taking account of both the effects can reproduce the decrease of gas holdup and energy consumption of bubble breakage arising from the increase of solid concentration. A new drag model is then derived from the PDBS model for CFD modeling. The CFD predictions of gas distribution under high solid loadings are in conformity with experimental data. The particle effect on stabilizing bubble surface is also analyzed for systems of non-wettable particles. The model reflects the increase of gas holdup with addition of non-wettable particles, and reveals also that small bubbles may dominate the system in such cases. Unlabelled Image • A PDBS model is proposed to analyze different particle effects on gas-liquid flows. • Particle effects on regime transition and gas holdup are reasonably reflected. • PDBS model reproduces gas holdup in systems of wettable or non-wettable particles. • CFD simulation with PDBS drag model gives good prediction at high solid loadings. [ABSTRACT FROM AUTHOR]

Slurry in wet grinding mills is critical for transporting fine progenies out of the system to downstream floatation process. It is commonly modelled as Newtonian fluids when simulating grinding mills with numerical tools. However, rheology of the slurry exhibits shear thinning non-Newtonian behaviours. This study aims to investigate the non-Newtonian characteristics of mineral slurries both experimentally and numerically. Non-Newtonian smoothed particle hydrodynamics (SPH) and its coupling to discrete element modelling (DEM) framework was initially described. Non-Newtonian rheology of a copper slurry with various solids concentrations was determined experimentally by a rotary viscometer. SPH-DEM modelling of the viscometry test was conducted with both Newtonian and Power-law non-Newtonian settings in fluid phase, and comparisons were performed. Results suggested that the non-Newtonian SPH based method better reflects actual rheological behaviours of the slurry. In addition, DEM parameters exhibited limited impacts on rheology of the solids-liquid mixture, particularly at low solids concertation and high shear rate states. The findings suggested that the non-Newtonian based SPH-DEM method should be used to more accurately model the slurry flows within grinding mills. Unlabelled Image • Non-Newtonian SPH-DEM coupling method incorporates the fluid rheology model • Mineral slurries exhibit the shear thinning non-Newtonian behaviour • Newtonian SPH-DEM incorrectly models the slurry rheology • DEM parameters may elevate the slurry rheology in SPH-DEM modelling [ABSTRACT FROM AUTHOR]

This study aims to examine the effect of an online lime separation system with the semi-dry scrubber and dry lime injection system in a refuse incineration plant. Fine powder was used to prepare different concentrations of lime slurry to remove four combinations of boiler outlet acid gas. Results show that the lime separation can reduce the particle size (D 90) of the hydrated lime from 31 to15 μm. The removal rate of HCl and SO 2 remains over 98% and 90%, respectively. If the SO 2 concentration in the gas is maintained below 200 mg/Nm3 via judicious refuse mixing, the consumption of lime will be most economical. Herein, the payback period of the facility will be approximately three years, and the online lime separation system can enhance the quality of hydrated lime, improve the emissions quality, reduce the consumption of lime, and achieve economic benefits. Unlabelled Image • The lime separation can reduce the particle size (D 90) of the hydrated lime from 31 to15 μm. • The removal rate of acid gas of HCl and SO 2 remains over 98% and 90%, respectively. • The payback period of the facility will be approximately three years. [ABSTRACT FROM AUTHOR]

Centrifugal high gradient magnetic separation (CHGMS) operates through a rotating matrix in a magnetic field, so that its separation performance is closely related to the coupling of magnetic field and rotating magnetic wires of the matrix. In this work, the capture characteristics of magnetic wires rotating at two different patterns, i.e., revolving around the center of separating cylinder and spinning around the axis of wire in a given uniform magnetic field, were comparatively described; and using a capture set-up, they were experimentally verified by their actual magnetic capture to ilmenite particles from a primary ilmenite concentrate assaying 13.04% TiO 2. It was found that the centrifugal force and hydrodynamic drag acting onto the particles of the spinning wire, as well as the required magnetic force to the particles for effective magnetic capture, is much smaller than that of the revolving wire. According to the COMSOL Multiphysics simulation, there is a large velocity gradient between the slurry around the rotating wire and the separating cylinder, producing a fluid shearing stress to particles in the slurry and thus improving the loose state of the slurry around the wire; in addition, the effect of wire spinning on the motion trajectories of particles is much weaker than that of the revolving one. The capture experiments indicated that the rotating pattern of wire has a significant effect on the capture characteristics; specifically, the spinning wire obtained a much higher mass weight for ilmenite particles but a similar capture selectivity, in comparison with the revolving wire. For instance, when the rotation of 6 mm diameter wire was transformed from revolution to spinning at the same rotation speed of 120 r/min, the mass weight of ilmenite particles captured onto the wire was significantly increased from 1.1 g/cm to 2.0 g/cm, while their TiO 2 grades reached 27.12% and 26.25%, respectively. It was concluded that the high capture selectivity of the rotating wire to ilmenite particles is primarily attributed to the effect of loosing particles in the fluid, as it facilitates the release of non-magnetic particles from the magnetic deposits captured on the wire surface. This investigation provides a valuable reference for the determination of matrix rotation pattern in the development of CHGMS technology. Figure. Required magnetic force for effective capture of revolving and spinning wires to particles. Unlabelled Image • The rotating wire produces a shearing force and a loosing effect to particles. • The revolving and spinning wires have significantly different capture characteristics. • This capture characteristics of rotating wires contributes to develop CHGMS method. [ABSTRACT FROM AUTHOR]

A combined Computational Fluid Dynamics and Population Balance Model (CFD-PBM) was developed to study the flow hydrodynamics of the slurry bed. The CFD-PBM applied a modified drag force model by considering the reduced drag force between gas and liquid phases at the presence of particle. Results show that the CFD-PBM with the modified drag force model can reasonably predict the flow hydrodynamics compared with the experimental data. It was predicted that the increased particle loading can enhance bubble coalescence to form larger bubbles, which can flow faster and reduce the gas holdup in the slurry bed. In addition, simulation results indicate that the particle flow becomes more non-uniform with much faster upward flow in the center and downward flow near the wall with the increase of superficial velocity. Particle back-mixing can be enhanced at higher superficial gas velocity, which can be beneficial for the reaction system with limited decrease in catalyst particle's reaction activity and unbeneficial for the reaction system with almost fully deactivation of catalyst. A modified drag force model was developed for describing the gas-liquid interactions by considering the presence of particle. The CFD-PBM with modified drag force model is accurate in predicting hydrodynamics in the slurry bed. Unlabelled Image • A modified gas-liquid drag force model was proposed at the presence of particle. • The CFD-PBM with modified drag force model is accurate in predicting hydrodynamics. • Increased particle loading can enhance bubble coalescence and reduce gas holdup. • Particle back-mixing can be enhanced at increased superficial gas velocity. [ABSTRACT FROM AUTHOR]

The main goal of this study was to assess the turbulent and hydrodynamics of the mixing of high solid loading slurries of large particles. To determine the state of homogeneity in the slurry tank, electrical resistance tomography was adopted. A computational fluid dynamics model was developed by employing the Eulerian-Eulerian multiphase model and the sliding mesh technique to explore the suspension of the large particles in the highly concentrated slurry tank. The influences of the solid loading, particle size, and impeller clearance on the homogeneity, just-suspended speed, power consumption, axial and radial velocities of the solid phase, and turbulent energy dissipation were assessed. It was found that the radial and axial velocities of the solid phase attained below the impeller plane at the just-suspended impeller speed were promoted by decreasing the particle size and increasing the solids loading while they were reduced with an increase in the impeller clearance. Image 1 • Mixing hydrodynamics of high-solid-content slurry of large particles was analyzed. • Tomography and CFD were employed to assess the suspension of solid particles. • The effects of solids loading, particle size, and impeller clearance were quantified. • Solid content, axial & radial velocity, and energy dissipation profiles were assessed. • Turbulent energy dissipation was enhanced with an increase in the solids loading. [ABSTRACT FROM AUTHOR]

The ilmenite lain in ultrafine ilmenite ore cannot be treated easily. In this study, a superconducting magnetic separator (SMS) was proposed to preconcentrate the ultrafine ilmenite. During this process, the essential condition for capturing the ilmenite from the ultrafine ore, key technology for obtaining an efficient preconcentration, and analysis of the ilmenite concentrates were investigated with theoretical descriptions, statistically designed experiments, and scanning electronic microscopy (SEM) detection, respectively. The descriptions and experiments indicated that the grade and recovery of ilmenite concentrate can be increased by the high-velocity slurry and high-intensity magnetic field, respectively; the synergy of the slurry velocity and magnetic intensity was demonstrated to be the key technology to improve the preconcentration efficiency. The SEM analysis demonstrated that the minimal agglomeration between ultrafine minerals in SMS further benefited the efficient preconcentration. Hence, the SMS provides an efficient way to preconcentrate ultrafine ilmenite ore. Image 1 • Superconducting magnetic separator preconcentrates ultrafine ilmenite ore. • Theoretical description analysed the requirement for separating ultrafine minerals. • The synergy of slurry velocity and magnetic intensity enhanced separation efficiency. • Response surface methodology adequately analysed and illustrated the synergy. • With the synergy, the agglomeration of minerals was avoided. [ABSTRACT FROM AUTHOR]

Thanks to the advancements in computer power and capability of Computational Fluid Dynamics codes, the amount of research work on the numerical simulation of slurry flows in pipelines has increased exponentially in few years, opening the way to the use of this approach for engineering purposes. The Two Fluid Model (TFM), in which both phases are interpreted as interpenetrating continua and solved in the Eulerian, cell-based framework, allows the best compromise considering the engineering requirements of computational efficiency, applicability, and accuracy. However, the solution of this model is affected by several numerical and modelling factors, and, even if good agreement is achieved between simulation results and experimental measurements, it might be difficult to trust the predictions outside the validation conditions, thereby limiting the engineering potential of the two-fluid approach. The fully-suspended slurry flow in horizontal pipes was numerically simulated using the TFM recently developed by one of the authors of this paper, and the computational results were compared to experimental data reported in the literature. It has been clearly demonstrated that, even in this simple geometry, many possible sources of inaccuracy and uncertainty come into play. Whilst assessing their role, best practice guidelines and consistency checks were proposed to improve the accuracy of the estimates and increase the reliability of the TFM solution. Afterwards, pipe size-up scaling tests and a careful specification of the applicability conditions provided further confidence to the use of the TFM as a tool for engineering design. Unlabelled Image • Convergence and sensitivity assessment followed by calibration and validation. • Critical inspection of diffcult-to-measure parameters. • Investigation of pipe size-up scalability of a two-fluid model. • Precise specification of the application domain. • Development of best practice guidelines for slurry pipe flow simulation. [ABSTRACT FROM AUTHOR]