Mechanical retention – Influence of filler floc size and grammage of the fibre web

2012 ◽  
Vol 27 (2) ◽  
pp. 202-207 ◽  
Author(s):  
Karin Athley ◽  
Lars Granlöf ◽  
Daniel Söderberg ◽  
Mikael Ankerfors ◽  
Göran Ström
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Pilot Trial ◽  
Average Particle ◽  
Paper Machine ◽  
Quartz Particle ◽  
Drainage Time ◽  
Fibre Layer ◽  
Filler Retention ◽  
The Impact

Abstract An investigation of the impact of particle size on the mechanical retention of particles in a fibre network has been conducted. The particles used were five sets of quartz particle fractions having fairly narrow particle size distributions with average particle size ranging from a few μm to around 100 μm. The particles were used to model flocculated filler aggregates as part of a larger study of the effect of pre-flocculation on mechanical retention. Pre-flocculation of the filler is a possible strategy to increase the filler content of paper without deterioration of strength properties. A modified laboratory hand sheet former, known as the Rapid Drainage Device (RDD) was used. The major modification consisted of a long pipe that acted as a suction leg, which provides a dewatering vacuum at the same level as on a paper machine. The experimental results showed that mechanical filler retention increased linearly with particle size and grammage of the fibre layer above a critical grammage which depended on particle size. The linear relation was also seen in a pilot scale trial on the FEX pilot-paper machine at Innventia. During this trial fine paper was produced using pre-flocculated filler where the mean particle size of the flocs and fibres was measured in the flow to the headbox. The results from this pilot trial show that mechanical retention is an important part of the total filler retention. Drainage time and therefore drainage resistance increased with the grammage of the fibre layer and amount of quartz particle added. Drainage time, compared at total grammage (i.e. the sum of fibre and quartz particle grammage) was lowest for a fraction of medium-sized particles, with a median size of 35 mm. There was no obvious effect on retention or drainage resistance of a change in the dewatering pressure from 27.5 to 41.5 kPa.

scholarly journals Water-Dispersible Phytosterol Nanoparticles: Preparation, Characterization, and in vitro Digestion

2022 ◽  
Vol 8 ◽  
Author(s):  
Ao Li ◽  
Aixia Zhu ◽  
Di Kong ◽  
Chunwei Wang ◽  
Shiping Liu ◽  
...  
Keyword(s):  
Particle Size ◽  
Soybean Lecithin ◽  
Average Particle Size ◽  
Soy Protein Isolate ◽  
In Vitro Digestion ◽  
Bimodal Distribution ◽  
Average Particle ◽  
Food Ingredients ◽  
The Impact

For improving solubility and bioaccessibility of phytosterols (PS), phytosterol nanoparticles (PNPs) were prepared by emulsification–evaporation combined high-pressure homogenization method. The organic phase was formed with the dissolved PS and soybean lecithin (SL) in anhydrous ethanol, then mixed with soy protein isolate (SPI) solution, and homogenized into nanoparticles, followed by the evaporation of ethanol. The optimum fabrication conditions were determined as PS (1%, w/v): SL of 1:4, SPI content of 0.75% (w/v), and ethanol volume of 16 ml. PNPs were characterized to have average particle size 93.35 nm, polydispersity index (PDI) 0.179, zeta potential −29.3 mV, and encapsulation efficiency (EE) 97.3%. The impact of temperature, pH, and ionic strength on the stability of fabricated PNPs was determined. After 3-h in vitro digestion, the bioaccessibility of PS in nanoparticles reached 70.8%, significantly higher than the 18.2% of raw PS. Upon freeze-drying, the particle size of PNPs increased to 199.1 nm, resulting in a bimodal distribution. The solubility of PS in water could reach up to 2.122 mg/ml, ~155 times higher than that of raw PS. Therefore, this study contributes to the development of functional PS-food ingredients.

scholarly journals Modeling of Miniemulsion Polymerization of Styrene with Macro-RAFT Agents to Theoretically Compare Slow Fragmentation, Ideal Exchange and Cross-Termination Cases

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 320 ◽  
Author(s):  
Dries Devlaminck ◽  
Paul Van Steenberge ◽  
Marie-Françoise Reyniers ◽  
Dagmar D’hooge
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Miniemulsion Polymerization ◽  
Monomer Conversion ◽  
Water Soluble ◽  
Explicit Calculation ◽  
Average Particle ◽  
Intermediate Radical ◽  
Raft Agent ◽  
The Impact

A 5-dimensional Smith-Ewart based model is developed to understand differences for reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerization with theoretical agents mimicking cases of slow fragmentation, cross-termination, and ideal exchange while accounting for chain length and monomer conversion dependencies due to diffusional limitations. The focus is on styrene as a monomer, a water soluble initiator, and a macro-RAFT agent to avoid exit/entry of the RAFT leaving group radical. It is shown that with a too low RAFT fragmentation rate coefficient it is generally not afforded to consider zero-one kinetics (for the related intermediate radical type) and that with significant RAFT cross-termination the dead polymer product is dominantly originating from the RAFT intermediate radical. To allow the identification of the nature of the RAFT retardation it is recommended to experimentally investigate in the future the impact of the average particle size (dp) on both the monomer conversion profile and the average polymer properties for a sufficiently broad dp range, ideally including the bulk limit. With decreasing particle size both a slow RAFT fragmentation and a fast RAFT cross-termination result in a stronger segregation and thus rate acceleration. The particle size dependency is different, allowing further differentiation based on the variation of the dispersity and end-group functionality. Significant RAFT cross-termination is specifically associated with a strong dispersity increase at higher average particle sizes. Only with an ideal exchange it is afforded in the modeling to avoid the explicit calculation of the RAFT intermediate concentration evolution.

Mechanical Properties of AA 5754 Hybrid Metal Matrix Composite Fabricated through Rheo-Squeeze Casting

2020 ◽  
Vol 979 ◽  
pp. 10-15
Author(s):  
K. Sekar ◽  
K. Jayakumar
Keyword(s):  
Particle Size ◽  
Tensile Strength ◽  
Metal Matrix ◽  
Squeeze Casting ◽  
Base Alloy ◽  
Average Particle Size ◽  
Casting Process ◽  
Matrix Alloy ◽  
Average Particle ◽  
The Impact

Hybrid metal matrix composites (MMCs) were prepared with AA 5754 as matrix and B4C (fixed with 1 wt.% and average particle size as 25 μm) and Al2O3 reinforcements (varied from 0.5 to 2 wt. % with the interval of 0.5 and average particle size as 50 nm) using Rheo-squeeze casting process. Microstructure images were taken to observe the uniform distribution of reinforcement particles on the matrix alloy. The tensile strength for AA 5754 with 1 wt.% B4C and 2 wt.% Al2O3 hybrid composite showed higher value compared to base alloy and other composites. The wt. % of Al2O3 in the composite is increased to 2 %, the tensile strength and compressive strength were also increased due to combined Rheo-squeeze casting. AA 5754 reinforced with 1 wt.% B4C and 1.5 wt.% Al2O3 MMC indicated the Impact strength value of 30 Joules which is higher than AA 5754 matrix alloy and other compositions.

scholarly journals Network high-performance grinding devices for ferromagnetic materials

2019 ◽  
Vol 135 ◽  
pp. 02019
Author(s):  
Yuriy Vernigorov ◽  
Valeriy Lebedev ◽  
Natalya Frolova ◽  
Kirill Leletko
Keyword(s):  
Magnetic Field ◽  
Particle Size ◽  
Translational Motion ◽  
Average Particle Size ◽  
Ferromagnetic Materials ◽  
Average Particle ◽  
Hammer Mill ◽  
Metal Powders ◽  
Design Features ◽  
The Impact

The design features of the grinding devices that implement the impact destruction of the ferromagnetic materials particles in a magneto vibrating layer formed in a non-uniform magnetic field are considered. It is shown that when a magnetizable powder is affected by an alternating magnetic field with certain parameters, a magneto vibrating layer is formed, under the conditions of which, a random perturbing factor occurs. It is caused by the dipole particles clusters interactions and provides highefficient finish powder grinding. Methods for producing metal powders, which are distinguished according to the operating principle and to the requirements for the technological properties of the powders obtained, are analyzed. For coarse grinding, jaw, roller and cone crushers and mullers are used; at this, particles of 1-10 mm in size, which are the source material for fine grinding, are obtained. The finish grinding of the material obtained is carried out on the ball rotating, vibrating or planar centrifugal, vortex and hammer mills. The main drawback of these techniques of metal powder grinding is sticking of grinding body residue on the powder particles, which reduces the quality and operational properties of the powder. A relation to calculate the dependence of the fineness number of ferromagnetic materials on the induction gradient of an external variable magnetic field is proposed. The design features of an electromagnetic mill based on a screw drum that, due to the spatial orientation of its walls, ensures an effective movement of powder flows inside it, such as mixing, rotation, oncoming movement, translational motion and simultaneous advancement through the drum are presented. The concept and technological options of grinding powders in an electromagnetic mobile hammer mill are revealed, which enables to obtain a powder of a given particle size distribution with high uniformity. It is established that mills in which a magneto vibrating layer is implemented are more effective than mechanical ones: grinding of ferromagnetic powders in a magneto vibrating layer increases drastically the performance of the grinding process. Changing the parameters of the electromagnetic field, you can set an average particle size and the degree of homogeneity of the powder.

scholarly journals β-hexanitrohexaazaisowurtzitane Particles Prepared by Spray Drying and its Characterization

2021 ◽  
Vol 27 (1) ◽  
pp. 119-124
Author(s):  
Wenzheng XU ◽  
Hao LI ◽  
Xin LIANG ◽  
Jie WANG ◽  
Jinyu PENG ◽  
...  
Keyword(s):  
Particle Size ◽  
Spray Drying ◽  
Ultrafine Particles ◽  
Average Particle Size ◽  
Narrow Particle Size Distribution ◽  
Average Particle ◽  
Thermal Stimulus ◽  
Particle Size Analyzer ◽  
Xrd Patterns ◽  
The Impact

In this paper, the ultrafine β-hexanitrohexaazaisowurtzitane (β – CL – 20) particles were prepared by spray drying method. The CL – 20 samples were characterized by scanning electron microscope (SEM), particle size analyzer, X-ray diffraction (XRD), and Differential Scanning Calorimeter (DSC). Furthermore, the safety properties of samples under impact and thermal stimulus were tested and analyzed. The results of SEM showed that the average particle size of ultrafine CL – 20 particles with a narrow particle size distribution, were about 320 nm, and the shape was elliptical. The XRD patterns indicated that the polymorphic phase of ultrafine particles was mainly β-type. Compared with that of raw CL – 20, the impact sensitivity of the ultrafine CL – 20 had been decreased significantly, for the drop height (H50) was increased from 13.0 to 33.5 cm. The critical explosion temperature of the ultrafine CL – 20 decreased from 232.16 ℃ to 227.93 ℃, indicating that the thermal stability of the ultrafine CL – 20 is lower than that of raw CL – 20.

scholarly journals High-Yield Production of Nano-Lateral Size Graphene Oxide by High-Power Ultrasonication

2021 ◽  
Author(s):  
Licínia Timochenco ◽  
Raquel Costa-Almeida ◽  
Diana Bogas ◽  
Filipa A.L.S. Silva ◽  
Joana Silva ◽  
...  
Keyword(s):  
Particle Size ◽  
High Power ◽  
Large Scale ◽  
Average Particle Size ◽  
High Yield ◽  
Average Particle ◽  
Scale Production ◽  
Lateral Size ◽  
Aqueous Dispersions ◽  
The Impact

Nanographene oxide (GOn) constitutes a nanomaterial of high value in the biomedical field. However, large scale production of highly stable aqueous dispersions of GOn is yet to be achieved. In this work, we explored high-power ultrasonication as a method to reduce particle size of GO and characterized the impact of the process in the physico-chemical properties of the material. GOn was obtained with lateral dimensions of 99 ±43 nm and surface charge of −39.9 ± 2.2 mV. High-power ultrasonication enabled an improvement of stability features, particularly by resulting in a decrease of the average particle size, as well as zeta potential, in comparison to GO obtained by low-power exfoliation and centrifugation (287 ± 139 nm; −29.7 ± 1.2 mV). Re-markably, GOn aqueous dispersions were stable for up to 6 months of shelf-time, with a global process yield of 74%. This novel method enabled the production of large volumes of highly con-centrated (7.5 mg mL-1) GOn aqueous dispersions. Chemical characterization of GOn allowed the identification of characteristic oxygen functional groups, supporting high-power ultrasonication as a fast, efficient and productive process for reducing GO lateral size, while maintaining the material’s chemical features.

scholarly journals High-Yield Production of Nano-Lateral Size Graphene Oxide by High-Power Ultrasonication

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1916
Author(s):  
Licínia Timochenco ◽  
Raquel Costa-Almeida ◽  
Diana Bogas ◽  
Filipa A. L. S. Silva ◽  
Joana Silva ◽  
...  
Keyword(s):  
Particle Size ◽  
High Power ◽  
Large Scale ◽  
Average Particle Size ◽  
High Yield ◽  
Average Particle ◽  
Scale Production ◽  
Lateral Size ◽  
Aqueous Dispersions ◽  
The Impact

Nanographene oxide (GOn) constitutes a nanomaterial of high value in the biomedical field. However, large scale production of highly stable aqueous dispersions of GOn is yet to be achieved. In this work, we explored high-power ultrasonication as a method to reduce particle size of GO and characterized the impact of the process on the physicochemical properties of the material. GOn was obtained with lateral dimensions of 99 ± 43 nm and surface charge of −39.9 ± 2.2 mV. High-power ultrasonication enabled an improvement of stability features, particularly by resulting in a decrease of the average particle size, as well as zeta potential, in comparison to GO obtained by low-power exfoliation and centrifugation (287 ± 139 nm; −29.7 ± 1.2 mV). Remarkably, GOn aqueous dispersions were stable for up to 6 months of shelf-time, with a global process yield of 74%. This novel method enabled the production of large volumes of highly concentrated (7.5 mg mL−1) GOn aqueous dispersions. Chemical characterization of GOn allowed the identification of characteristic oxygen functional groups, supporting high-power ultrasonication as a fast, efficient, and productive process for reducing GO lateral size, while maintaining the material’s chemical features.

scholarly journals Green Synthesis and the Study of Some Physical Properties of MgO Nanoparticles and Their Antibacterial Activity

2020 ◽  
pp. 266-276
Author(s):  
Rand Ali ◽  
Zainab Jassim ◽  
Ghada Muhammad Saleh ◽  
Quraysh Abass
Keyword(s):  
Particle Size ◽  
Antibacterial Activity ◽  
Energy Gap ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Magnesium Nitrate ◽  
Average Particle ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Impact

     Magnesium oxide nanoparticles (MgO NPs) were synthesized by a green method using the peels of Persimmon extract as the reducing agent , magnesium nitrate, and NaOH. This method is eco-friendly and non-toxic. In this study, an ultrasound device was used to reduce the particle size, with the impact on the energy gap was set at the beginning at 5.39 eV and then turned to 4.10 eV. The morphological analysis using atomic force microscopy (AFM)  showed that the grain size for MgO NPs was 67.70 nm which became 42.33 nm after the use of the ultrasound. The shape of the particles was almost spherical and became cylindrical.  In addition the Field-Emission Scanning Electron Microscopy (FESEM) analysis showed that the average particle size was reduced and the spherical shape was changed into cylindrical flakes. The antibacterial activity of MgO Nps was measured against both gram positive and negative bacteria (Staphylococcus aureus and Escherichia coli, respectively) for both the synthesized and the scaled-down particles by the ultrasonic. MgO NPs showed an efficacy at a minimum inhibitory concentration (MIC) of 500 μg/ml, with the better effect being observed after the ultrasonic treatment of the MgO NPs.

Determination of grinding parameters of fenugreek seed

1970 ◽  
Vol 26 (1) ◽  
pp. 16 ◽  
Author(s):  
S Balasubramanian ◽  
Rajkumar Rajkumar ◽  
K K Singh
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Moisture Content ◽  
Specific Energy ◽  
Feed Rate ◽  
Average Particle Size ◽  
Specific Energy Consumption ◽  
Average Particle ◽  
Fenugreek Seeds ◽  
Fenugreek Seed

Experiment to identify ambient grinding conditions and energy consumed was conducted for fenugreek. Fenugreek seeds at three moisture content (5.1%, 11.5% and 17.3%, d.b.) were ground using a micro pulverizer hammer mill with different grinding screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg h-1) at 3000 rpm. Physical properties of fenugreek seeds were also determined. Specific energy consumptions were found to decrease from 204.67 to 23.09 kJ kg-1 for increasing levels of feed rate and grinder screen openings. On the other hand specific energy consumption increased with increasing moisture content. The highest specific energy consumption was recorded for 17.3% moisture content and 8 kg h-1 feed rate with 0.5 mm screen opening. Average particle size decreased from 1.06 to 0.39 mm with increase of moisture content and grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg h-1 feed rate at lower moisture content. Bond’s work index and Kick’s constant were found to increase from 8.97 to 950.92 kWh kg-1 and 0.932 to 78.851 kWh kg-1 with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of fenugreek seed were found to decrease from 4.11 to 1.61 and 0.0118 to 0.0018 with the increase of moisture content, feed rate and grinder screen opening, respectively. The loose and compact bulk densities varied from 219.2 to 719.4 kg m-3 and 137.3 to 736.2 kg m-3, respectively.  

Influence of temperature and humidity on the angle of repose of wood bulk materials

2016 ◽  
Author(s):  
И.В. Бачериков ◽  
Б.М. Локштанов
Keyword(s):  
Field Experiments ◽  
Bulk Material ◽  
Average Particle Size ◽  
Operating Conditions ◽  
Angle Of Repose ◽  
Wood Dust ◽  
Average Particle ◽  
Bulk Materials ◽  
Technical Literature ◽  
The Impact

При проектировании открытых и закрытых хранилищ измельченных сыпучих материалов древесных материалов, таких как щепа и опилки, большое значение имеет угол естественного откоса (статический и динамический) этих материалов. В технической литературе приводятся противоречивые сведения о величине этих углов, что приводит к ошибкам при проектировании складов. В справочных данных не учитываются условия, в которых эксплуатируются емкости для хранения сыпучих материалов, свойства и состояние этих сыпучих материалов. В свою очередь, ошибки при проектировании приводят к проблемам (зависание, сводообразование, «затопление» и т. д.) и авариям при эксплуатации бункеров и силосов на производстве. В статье представлены сведения, посвященные влиянию влажности и температуры на угол естественного откоса сыпучих материалов. На основании лабораторных и натурных экспериментов, проведенных с помощью специально разработанных методик и установок, была скорректирована формула для определения углов естественного откоса (статического и динамического) для измельченных древесных материалов в зависимости от их фракционного и породного состава, влажности (абсолютной и относительной) и температуры. При помощи скорректированной формулы можно определить угол естественного откоса древесных сыпучих материалов со среднегеометрическим размером частицы от 0,5 мм до 15 мм (от древесной пыли до технологической щепы) в различных производственных условиях. Статья может быть полезна проектировщикам при расчете угла наклона граней выпускающей воронки бункеров и силосов предприятий лесной отрасли и целлюлозо-бумажной промышленности. In the design of open and closed storage warehouses chopped wood materials for bulk materials such as wood chips and sawdust, great importance has an angle of repose (static and dynamic) of these materials. In the technical literature are conflicting reports about the magnitude of these angles, which leads to errors in the design of warehouses. In the referencesdoes not take into account the conditions under which operated capacities for storage of bulk materials, and properties and condition of the bulk material. The design errors lead to problems (hanging, arching, «flooding», etc.) and accidents in the operation of hoppers and silos at the mills. The article provides information on the impact of humidity and temperature on the angle of repose of granular materials. On the basis of laboratory and field experiments, conducted with the help of specially developed techniques and facilities has been adjusted formula for determining the angle of repose (static and dynamic) for the shredded wood materials depending on their fractional and species composition, humidity (absolute and relative) and temperature. It is possible, by using the corrected formula, to determine the angle of repose of loose wood materials with average particle size of from 0.5 mm to 15 mm (wood dust to pulpchips) in various operating conditions. The article can be helpful to designers in the calculation of the angle of inclination of the funnel faces produces bunkers and silos forest industries and pulp and paper industry.

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