Median Particle Size Research Articles

Effect of Ball Milling Conditions on the Microstructure and Dehydrogenation Behavior of TiH2 Powder

This study investigated the effects of revolution speed and ball size in planetary milling on the microstructure and dehydrogenation behavior of TiH2 powder. The particle size analysis showed that the large particles present in the raw powder were effectively refined as the revolution speed increased, and when milled at 500 rpm, the median particle size was 1.47 m. Milling with a mixture of balls of two or three sizes was more effective in refining the raw powder than milling with balls of a single size. A mixture of 3-mm and 5-mm-diameter balls was the optimal condition for particle refinement, and the measured median particle size was 0.71 m. The dependence of particle size on revolution speed and ball size was explained by changes in input energy and the number of contact points of the balls. In the milled powder, the endothermic peak measured using differential thermal analysis was observed at a relatively low temperature. This finding was interpreted as the activation of a dehydrogenation reaction, mainly due to the increase in the specific surface area and the concentration of lattice defects.

Predictive computational models for assessing the impact of co-milling on drug dissolution

Co-milling is an effective technique for improving dissolution rate limited absorption characteristics of poorly water-soluble drugs. However, there is a scarcity of models available to forecast the magnitude of dissolution rate improvement caused by co-milling. Therefore, this study endeavoured to quantitatively predict the increase in dissolution by co-milling based on drug properties. Using a biorelevant dissolution setup, a series of 29 structurally diverse and crystalline drugs were screened in co-milled and physically blended mixtures with Polyvinylpyrrolidone K25. Co-Milling Dissolution Ratios after 15 min (COMDR15 min) and 60 min (COMDR60 min) drug release were predicted by variable selection in the framework of a partial least squares (PLS) regression. The model forecasts the COMDR15 min (R2 = 0.82 and Q2 = 0.77) and COMDR60 min (R2 = 0.87 and Q2 = 0.84) with small differences in root mean square errors of training and test sets by selecting four drug properties. Based on three of these selected variables, applicable multiple linear regression equations were developed with a high predictive power of R2 = 0.83 (COMDR15 min) and R2 = 0.84 (COMDR60 min). The most influential predictor variable was the median drug particle size before milling, followed by the calculated drug logD6.5 value, the calculated molecular descriptor Kappa 3 and the apparent solubility of drugs after 24 h dissolution. The study demonstrates the feasibility of forecasting the dissolution rate improvements of poorly water-solube drugs through co-milling. These models can be applied as computational tools to guide formulation in early stage development.

Replacing Fly Ash or Silica Fume with Tuff Powder for Concrete Engineering in Plateau Areas: Hydration Mechanism and Feasibility Study

Abundant tuff mineral resources offer a promising solution to the shortage of fly ash (FA) and silica fume (SF) resources as emerging supplementary cementitious materials. However, a lack of clarity on its hydration mechanism has hindered its practical engineering application. In this study, high SiO2-content tuff powder (TP) was examined to assess the mechanical and workability performance of mortar specimens with varying particle sizes of the TP as complete replacements for FA or SF. Microscopic analysis techniques, including X-ray diffraction (XRD), differential thermal analysis (DTG), and energy-dispersive X-ray spectroscopy (EDS), were employed to elucidate the hydration mechanism of the TP and its feasibility as a substitute for SF or FA. Results indicated that TP primarily functions as nuclei and filler, promoting cement hydration, with smaller particle sizes amplifying the hydration ability and increasing Ca(OH)2 and C-S-H gel content. The specimens with TP (median particle size 7.58 μm) demonstrated 9.2% and 29.9% higher flexural and compressive strengths at 28 days, respectively, compared to the FA specimens of equal mass. However, fluidity decreased by 23.1% accordingly. Due to TP’s smaller specific surface area compared to SF, the TP specimens exhibited higher fluidity but with decreased strength relative to the SF specimens. Overall, TP shows potential as a replacement for FA with additional measures to ensure workability.

Synthesis, investigation of temperature and salt resistant polyacrylamide microspheres used for deep sealing and profile control and function strengthening mechanism

AbstractBased on the requirements of deep sealing and profile control for the excellent temperature and salt resistance on polyacrylamide microspheres, the Poly‐AM/AMPS was prepared depends on aqueous solution polymerization method to improving oil and gas recovery efficiency in low‐permeability and heterogeneous reservoirs resulted by water channeling. The key technical parameters were established through single‐factor experimental methods, and the chemical structure was studied by infrared spectrum analysis (FTIR), energy spectrum analysis, and x‐ray diffraction analysis, and then the thermal stability was investigated depends on the thermogravimetric (TG) and differential thermogravimetric (DTG) distribution curves, moreover, the particle size and distribution, microstructure, and surface morphology were further studied. As a result, the results confirmed that the molecular structure of Poly‐AM/AMPS meets the expected design, and the quality retention rate at 800°C is 17.4%, the median particle size of Poly‐AM/AMPS particles is 35.88 μm, and the particle size distribution range is about 1.94–497.8 μm. Further, the Poly‐AM/AMPS was modified by maleic anhydride, sodium styrenesulfonate, and dimethyl diallyl ammonium chloride through conventional functional strengthening and modification, modified by nano‐SiO2, GO, and S‐CaCO3 through nano‐functional strengthening and modification. Additionally, the functional strengthening and modification mechanism was studied depends on the FTIR, TG, and DTG methods.

Copper heap leach residue aggregates in concrete: Properties and performance

This study assesses the feasibility of using copper heap leach residue (CHLR) as a sustainable alternative to natural aggregates in concrete production. The CHLR possesses flaky-angular shape grains with rough surface texture and microcracks, crystalline silica of 51.6 %, 6.1 mg/g silt-clay with a median particle size of 4.3 mm, and it becomes suitable for the partial replacement of natural fine and coarse aggregates after removing 4.2 mg/g fines through 60-minute wash. Concrete containing 25–75 % CHLR aggregates met design slump and air content of 125±25 mm and 2±0.5 %, respectively, while also demonstrating a negligible 2.9 % reduction in fresh density and 2.8 % increase in compaction factor. Concrete containing 50 % CHLR as a partial replacement of natural coarse and fine aggregates achieved compressive strengths of 47.3 MPa and 45.1 MPa at 28 days, while the compressive strength of control mix was 46.7 MPa. The mechanical properties significantly declined at 75 % CHLR incorporated concretes. The BSE-EDS analysis highlighted improved interfacial transition zone for CHLR aggregates with minimal microcracks at early age compared to the natural aggregates but developed interfacial transition zone microcracks with prolonged curing leading to a decline in mechanical strength development.

Multi-Parameter Experimental Research on the Expansion Force Affecting Lime-Sand Piles under Preloading Pressure

Aiming at the problems that it is difficult to control the expansion force of lime-sand pile in the foundation correcting and how the upper existing structural pressure affects the expansion force of lime-sand pile, this paper adopts a new type of lime-sand pile reaction tester to carry out the experimental research on the expansion force of lime-sand pile under the influences of different pre-pressure, different mixing ratios, different heights, and different granular sizes. The purpose of this paper is to explore the influence of the pre-pressure brought by the existing building structure on the expansion force of the lime-sand pile and the coupling effect of the pre-pressure and other influencing factors on the expansion force of the lime-sand pile through the multi-parameter test. The results show that with the increase in pre-pressure, the expansion force of the lime-sand pile shows the trend of increasing first and then decreasing when the pre-pressure is 0.88 KN, the effect is most obvious and its expansion force can be increased by 14.9%. Within a certain range, the larger the proportion of quicklime is, the lower the expansion reaction force is. The expansion force of the lime-sand pile with the ratio of lime/sand/soil of 5:4:1 is the most ideal, and its value reaches 10.2 KN, which is 10% and 15.3% higher than the rest of the two groups, respectively. Within a certain range, the effect of specimen height change on the expansion force of the lime-sand pile is almost negligible. The smaller particle size of quicklime makes its reaction speed faster, the reaction degree is more full, and the expansion force is greater. The expansion force of the small particle size group was 12.1% and 34.2% higher than that of the medium and large particle size groups, respectively.

Effect of milling and compaction on sintering of porcelain stoneware tiles

The present study aims to provide a deeper understanding of how different particle size distributions and degrees of powder compaction affect the densification process of porcelain stoneware tiles. For this purpose, three different batches underwent a laboratory simulation of the industrial tilemaking process, at growing grinding time or increasing forming pressure, with technological characterization of both unfired and fired products. Sintering behaviour was determined by hot-stage microscopy. Phase composition was determined by XRD-Rietveld allowing the estimation of the chemical composition and physical properties of the liquid phase. The results illustrate the impact of too fine (or too coarse) grain size on powder compaction, firing shrinkage, water absorption, efficiency of densification, sintering rate, stability at high temperature, and risk of anticipated overfiring (and similarly for too high or too low forming pressure). Simultaneous variation of particle size and forming pressure beyond usual standards induced changes in technological behaviour that in most cases compensate each other. Phase composition is moderately influenced by particle size and little by powder compaction. The vitreous phase mainly suffered from a decreasing degree of polymerization as the particle size became finer or the dry bulk density decreased. In case of insufficient grinding, too much residual feldspars caused improper composition and properties of the glassy phase, which resulted in lower efficiency of densification and slower sintering rate. Both the sintering kinetics and degree of densification depend on the timescale, i.e. the ratio of surface tension to viscosity (melt) and median particle size. Nevertheless, a low powder compaction can trigger a microstructural effect on sintering (improving both densification rate and efficiency) that may outweigh the timescale effect.

Improvement of the mechanical properties of beta-hemihydrate phosphogypsum by incorporating wet-ground low-calcium fly ash slurries

Beta-hemihydrate phosphogypsum (β-HPG) is a low-carbon cementitious material used in construction. Nevertheless, the poor water resistance and low mechanical strength of β-HPG limit its utilization. In this study, two low-calcium fly ash (FA) slurries with median particle sizes of 1.83 μm and 1.14 μm were prepared using a wet-grinding process for the improvement of β-HPG, and the mechanical strength and softening coefficient were tested to assess the effect. The results show that wet-ground low-calcium FA can significantly enhance the mechanical strength and softening coefficient of β-HPG. Compared with specimens without wet-ground low-calcium FA, the dry compressive strength and softening coefficient of specimens with 30% wet-ground low-calcium FA (D50=1.14 μm) increased by 104.9% and 71.8%, respectively. It is worth noting that the 1 d compressive strength also increased by 11.9%. Specifically, wet-ground low-calcium can increase the pH value and conductivity of the FA slurry, further accelerate the hydration process of FA in β-HPG, forming more ettringite and gels to fill in the pores between dihydrate gypsum (DH) crystal, and reducing the larger pores in the hardened paste. This study can develop a high-performance cementitious material that will enable the effective use of β-HPG.

Effect of wet milling activation on mechanical properties and hydration process of cement composites with blast furnace slag

In this study, blast furnace slag (BFS) was activated using water- and ethanol-assisted milling (AM). BFS-cement composites (BFS-CC) were prepared using milled BFS and cement. The effects of the activation process on the mechanical properties and hydration of BFS-CC were investigated. Results showed that water- and ethanol-AM significantly reduced the median particle size (D50) and improved the particle size distribution of BFS compared to dry milling. Water-AM increased the compressive strength of BFS-CC at 3 days by 19.9 % and decreased the compressive strength at 28 days by 6.7 %. While ethanol-AM increased the compressive strengths at 3 and 28 days by 17.2 and 22.4 %, respectively. Water-AM improved the early strength of BFS-CC, whereas ethanol-AM contributed significantly to the late strength development of BFS-CC. This study provides an effective and convenient method for regulating the mechanical properties of cement composites containing high-volume BFS.

Investigation on the Micro-Grinding Induced Crystallographic Variations of Nine Different Clinkers

Although clinker has been used for many years, complicated mineralogical properties of clinker pose challenges for the precise quantification. In this study, the mineralogical and crystallographic properties of nine different clinkers according to grinding procedures were investigated. With the dry-grinding for 2 h, particle size reduction to 3 μm of median particle size with a substantial phase transition to an amorphous phase observed, to which alite (C3S) mainly contributed to the transition. Meanwhile, the crystallographic properties of the clinker phases were barely changed during the wet-grinding. In the wet-grinding program, the amount of ferrite solid solution (C4AF) with a high linear absorption coefficient was not underestimated. Furthermore, well-corrected preferred orientation effect on C3S was positively contributed to the analysis result of clinkers with the wet-grinding. Hence, it was suggested that the crystallographic effects observed in the wet-grinding program could produce more reliable results in phase analysis for the clinkers.

The Influence of Freezing-thawing on the Properties of Sludge from Water Treatment Facilities and the Prospects for its Disposal

It has been shown that the freezing-thawing method allows a sharp increase in the water-yielding capacity of water treatment sludge (WTS sludge) and leads to an increase in the median particle size of the dispersed phase of sludge. The distribution of bound water types in WTP sludge was studied using thermogravimetry (TG), differential thermal thermogravimetry (DTG), differential scanning calorimetry (DSC) and mass spectrometry of gaseous thermolysis products (MS). It has been established that the release of water and carbon dioxide is completely completed at a temperature of 600°C. The specific surface area of the solid phase of WTP sludge before and after freezing-thawing was determined. The pore size distribution was studied. The BET isotherm of WTP sludge corresponds to mesoporous sorbents.

Production of recycled paper using harmless municipal sludge as a new biomass filler

Abstract Due to a shortage of resources, exploring new biomass fillers has become critical for paper making. In this study, we reported an eco-friendly strategy for fabricating low-cost and efficient recycled paper with high mechanical properties using corrugated cardboard waste paper and harmless municipal sludge (HMS). First, the characteristics of HMS, including the particle size, pH, specific surface area, organic functional groups and organic component content, were analyzed. Then, the influence of the amount of HMS on the properties of the recycled paper was studied. Finally, the strengthening mechanism of biomass filling recycled paper was discussed. The results showed that HMS, a biomass filler for recycled paper preparation, exhibited excellent physical and chemical properties, with a median particle size of 6.395 μm, a surface area of 39.974 m2 g−1 and organic functional groups. The tensile index of the recycled paper with 30 % HMS was 13.10 Nm/g, which was 16.4 % greater than that of the unfilled paper and showed better thermal stability. This excellent performance could be attributed to the uniform distribution of HMS on the fiber surface, which improved the accessibility of hydrogen bond formation between fibers. Thus, this study proved that HMS was an excellent biomass filler for producing recycled paper.

Experimental Study on Tailings Deposition Distribution Pattern and Sedimentation Characteristics.

Tailings pond accidents frequently occur during an extended period, resulting in loss of life and property, wastage of resources, and environmental pollution. Relying on tailings pond engineering, this paper carried out sample particle fragmentation experiments and settling column experiments to explore the deposition distribution pattern of tailings in both horizontal and vertical directions as well as the impact of particle size distribution on the sedimentation stratification effect. The results show that the median particle size on the dry beach surface in the horizontal direction slowly decreased with the increase in the distance from the subdam. The particle size of tailings showed great fluctuations in the vertical direction, which gradually became finer with the increase in the depth overall. At the same time, saturated sedimentation experiments suggested the inconsistent variation rule with the field test, namely, coarse on the bottom and fine at the top, and the change in particle size greatly affected the tailing sedimentation stratification effect. With the increase in fine particle content in tailings, the appearance time of the water-sand interface was shortened to within 30 min, but the sedimentation and consolidation completion times were delayed to about 1400 min. The settling column results indicate that the increase in fine particle content gradually weakened the sedimentation stratification effect, and the sedimentation pattern transformed from independent sedimentation to floc-type average sedimentation, which led to the enhanced water-retaining property of the settled layer. This may lead to an increase in the saturation line and a decrease in the length of the dry beach, seriously affecting the safe operation of the tailings pond. The research results provide some theoretical guidance and basic data for analyzing the consolidation efficiency of tailings and the stability of the tailings pond.

Supplementary cementitious material based on calcined montmorillonite standards

The most effective approach to mitigating the environmental impact of cement production is through the utilisation of pozzolanic materials to prepare blended cement. Calcined kaolinitic clays are one of the most promising materials to be used as supplementary cementitious materials (SCM) due to their final performances. However, there are locations where kaolinitic rocks are not available. This work presents the study of two dioctahedral smectite standards from the Clay Minerals Society (CMS), SWy-3 and SAu-1, to be used as references. After thermal activation optimisation, their pozzolanic performances are compared with those of low-grade kaolinitic clay. On the one hand, raw SWy-3 has an amorphous content of ∼80 wt%, considered montmorillonite, with quartz and feldspars. The optimum calcination temperature was 800ºC, at which the smectite is fully dehydroxylated (as determined by thermal analysis) but not completely amorphized (as shown by powder diffraction). After calcination (800ºC), with a median particle size by volume (Dv,50) of ∼11 μm, ∼480 J/g were released at 7 days in the R3 test. On the other hand, SAu-1 has a higher amount of amorphous content, ∼96 wt%, which includes interstratified illite/smectite. The optimum calcination temperature was found to be 750ºC. This sample (Dv,50 ∼10 μm) gave 452 J/g at 7 days in the R3 test. The optimised active smectites gave a pozzolanic activity comparable to clay with 30–35 % kaolinite, as determined, for the first time, by the R3 test. This work has established descriptors for the activation of natural smectites/bentonites and reference values for the resulting smectite-based SCMs.

Effect of synergistic fermentation of Saccharomyces cerevisiae and Lactobacillus plantarum on thermal properties of hyaluronic acid-wheat starch system

Hyaluronic acid (HA), as a multifunctional hydrophilic polysaccharide, is potentially beneficial in improving the thermal stability of fermented modified starches, but relevant insights at the molecular level are lacking. The aim of this study was to investigate the effect of different levels (0 %, 3 %, 6 %, 9 %, 12 % and 15 %) of HA on the structural, thermal and pasting properties of wheat starch co-fermented with Saccharomyces cerevisiae and Lactobacillus plantarum. We found that the addition of HA increased the median particle size of fermented starch granules from 16.387 to 17.070 μm. Meanwhile, the crystallinity of fermented starch was negatively correlated with the HA content, decreasing from 14.70 % to 12.80 % (p < 0.05). Fourier transform infrared spectroscopy results confirmed that HA interacted with starch granules and water molecules mainly through hydrogen bonding. Thermal analyses showed that the thermal peak of the composite correlated with the HA concentration, reaching a maximum of 73.17 °C at 12 % HA. In addition, HA increases the pasting temperature, reduces the peak, breakdown and setback viscosities of starch. This study demonstrates the role of HA in improving the thermal stability of fermented starch, providing new insights for traditional fermented food research and the application of HA in food processing.

Characterization of stratospheric particle size distribution uncertainties using SAGE II and SAGE III/ISS extinction spectra

Abstract. A new algorithm was developed to infer particle size distribution parameters from the Stratospheric Aerosol and Gas Experiment II (SAGE II) and SAGE III on the International Space Station (SAGE III/ISS) extinction spectra using a lookup table (LUT) approach. Here, the SAGE-based extinction ratios were matched to LUT values, and, using these matches, weighted statistics were calculated to infer the median particle size distribution values and higher-moment parameters as well as quantify the uncertainty in these estimates. This was carried out by solving for both single-mode and bimodal lognormal distributions. The work presented herein falls under two general headings: (1) a theoretical study was carried out to determine the accuracy of this methodology, and (2) the solution algorithm was applied to the SAGE II and SAGE III/ISS records with a brief case study analysis of the 2022 Hunga Tonga eruption. This methodology was demonstrated to be ≈ 25 % accurate for mode radius and has a minor dependence on particle composition. While bimodal solutions were obtained from this algorithm, we provide a conclusive demonstration of how and why these estimates are inherently unstable using SAGE III/ISS extinction spectra alone. Finally, we demonstrated how the Hunga Tonga aerosol plume evolved in regard to both size and transport over 18 months after the 2022 Hunga Tonga eruption. The particle size distribution (PSD) estimates, higher-moment parameters, and uncertainties are new products within the SAGE III/ISS Level 2 (L2) products, are currently available for download, and will be merged into the main SAGE III/ISS release products in a subsequent L2 release.

Experimental Study on the Sedimentation Performance of an Arc-Plate Linear Sedimentation Tank

To examine the influence of plate shapes and quantities on the sedimentation performance of a linear sedimentation tank, experimental research was conducted using tanks featuring five distinct plate structures. The findings reveal that when subjected to an inflow rate ranging from 60 to 100 m3/h and with median particle sizes of 571.110 μm and 162.254 μm, for sediment particles in water containing sediment, the flow field distribution in the arc-plate sedimentation tank facilitates the effective settling of sediment particles. Comparative analyses indicate that incorporating eight arc plates in the sedimentation tank, as opposed to an equal number of inclined plates, results in a notable reduction in surface sediment concentration within the plate region, ranging from approximately 8 to 34%. Additionally, the mass percentage of sediment particles with sizes less than 0.05 mm at the tank bottom increases by about 5–7%. Moreover, in comparison to tanks lacking plates and those equipped with four arc plates, the surface sediment concentration experiences a significant decrease, ranging from approximately 33% to 60% and 18% to 44%, respectively. Concurrently, the mass percentage of sediment particles with sizes less than 0.05 mm shows an increase of about 25–32% and 10–20%. The arc-plate sedimentation tank exhibits superior sedimentation efficiency with an inflow rate of 60 m3/h and the installation of eight arc plates. Additionally, the study concludes that increasing the number of plates and reducing the inflow rate enhance sediment settling. The research findings offer valuable insights for the design and advancement of sedimentation tanks.

Visualization of phenanthrene effect on biochar colloids transport in porous media

Biochar colloids (BCs) can be used as adsorbent materials for remediation of phenanthrene due to their high specific surface area and other characteristics. Understanding the effects of phenanthrene on the transport of BCs contributes to facilitate the removal of phenanthrene in soil and water habitats. In this work, the influence of phenanthrene on the transport of BCs under different environmental factors (pH, ionic strength (IS), media size) in a one-dimensional sand column was firstly explored together with a real-time visualization system to explore the transport mechanism of BCs in two-dimensional sand tank. The results show that phenanthrene adsorbed on the surface of BCs, shielded its surface charge and reduced the mobility of BCs in porous media. Acidic conditions promoted the agglomeration of BCs and adsorption of phenanthrene, resulting in a 51.03 % decrease in the maximum breakthrough rate of BCs compared to alkaline conditions. The same was true for the high IS condition, where the maximum breakthrough rate of BCs was only 0.95 % at IS = 50. Additionally, there was a substantial and positive correlation between media particle size and BCs mobility. As the quartz sand particle size increased, the maximum breakthrough rates of BCs were 2.67 %, 33.28 %, and 52.27 % in the 1-D experiment, and 0, 13.88 %, and 13.10 % in the 2-D experiment, respectively. The contact area of BCs with the medium expands under the fine particle size condition, leading to a significant decrease in the mobility of BCs at low potentials influenced by phenanthrene. This finding is significant for biochar application in phenanthrene contaminated soil and groundwater remediation.

Effect of particles on foam drainage

Despite many applications, the three phase foam is so complicated and far from being fully understood. Drainage is critical to foam decay, so the effect of particles on foam drainage has been investigated in this research to better understand the complex three phase foam. The power law relationship, drainage regime, foam permeability and the residual solid particles were investigated with different particle concentration, particle hydrophobicity and particle size. It was found that the power law index increased with the increasing of particle concentration and particle hydrophobicity, which indicates the transition of drainage regime from node dominated to Plateau border dominated. It was also found that the medium size particles could increase the Plateau border viscous loss more obviously. Foam permeability with different particles was also discussed via fitting the viscous loss of both Plateau border and nodes. Finally, residual solid particle was used to study the particle behaviour during the free drainage after forced drainage. This research could help us better understand the drainage of three phase foam.

Study on the Preparation of Spherical Nanosilver Particles Using Ammonium Citrate and Polyvinyl Alcohol as Surfactants

Spherical nanosilver particles were synthesized using ammonium citrate (AC) and polyvinyl alcohol (PVA) as surfactants. The synthesis conditions were optimized as follows: pH of 8, molar ratio of ascorbic acid (AA) to silver nitrate (AgNO3) at 0.75, AgNO3 concentration of 5 g·L−1, mass ratio of AC to PVA at 0.05, and mass ratio of PVA to AgNO3 at 0.1. Under the optimal conditions, the median particle size of the prepared silver particles was 0.52 μm, with an average size of 0.49 μm. The particle size distribution was narrow, and the particles exhibited a smooth surface with excellent dispersion characteristics.