Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.powtec.2021.02.072

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Language：Japanese   Publishing type：Research paper (scientific journal)  

J-GLOBAL

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J-GLOBAL

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Language：Japanese   Publishing type：Research paper (scientific journal)  

J-GLOBAL

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J-GLOBAL

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Cobalt blue is one of the most chemically and thermally stable blue pigments. However, cobalt is scarce and expensive. To minimize the use of cobalt and reduce production costs and toxicity, cobalt blue core-shell pigments were synthesized by a solid-state method, which is cheaper than a liquid-phase reaction. Small cobalt hydroxide particles and large -alumina particles, in various ratios, were used as the starting materials. The dry mixed powders were calcined at 1200 degrees C for 2hours. Elemental mappings of the surfaces and cross sections of the synthesized particles showed that the cobalt blue had a core-shell structure. X-ray diffraction patterns showed that the synthesized cobalt blue consisted of an -alumina core and a cobalt aluminate shell. The color tone of the synthesized cobalt blue was evaluated from the lightness (L*) and chroma (C*) values. The color tone of the cobalt blue synthesized in this study was almost same as those of commercially available samples although the cobalt molar fraction was lower than the stoichiometric ratio (Co/(Co+Al)=0.33, Co/Al=0.5) which was calculated from the chemical reaction formula.

DOI： 10.1111/jace.16191

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Particle flowability can be improved by admixing with particles smaller than the main particles. However, the mechanism by which this technique improves flowability is not yet fully understood. In this study, we focused on vibrating discharge particle flowability as one type of flowability and investigated the influence of the main particle roughness created by the adhesion of the admixed particles on improving the flowability. The diameters of the main and admixed particles (MPs and APs) were 41.4 or 60.8 mu m and 8 or 104 nm, respectively. The main and admixed particles were mixed in various mass ratios, and the discharge particle flow rates of the mixed particles were measured. Scanning electron microscopy images were acquired from two different angles to determine the three-dimensional surface roughness using image analysis software. We then calculated the coating structure parameters from the obtained three-dimensional surface roughness. The observed trends for improving the vibrating discharge particle flowability were found to differ from those reported for compression particle flowability. Furthermore, the main particle roughness conditions that led to the greatest improvement involved the presence of several admixed particle agglomerations between the main particles. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2018.10.018

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Publishing type：Research paper (scientific journal)  

The color tone of pigments is affected by various factors such as crystal structure and particle size. These characteristics should be determined by synthesis condition. In this study, the influence of cobalt source on the color tone of cobalt blue pigment was investigated. Cobalt blue (CoAl2O4) was synthesized by solid-state reaction method. Co3O4 and Co(OH)2 with two different particle sizes were used as the cobalt source, and γ-Al2O3 was used as the aluminum source. The products were characterized by spectrophotometry, XRD, SEM, and TG/DTA. It was revealed that the chroma of the synthesized cobalt blue depends on the cobalt source. The cobalt blue synthesized using smaller size Co(OH)2 showed most vivid color. It was suggested that the number of the contact points between the starting materials increased with decreasing the particle size, leading to the progress of the reaction.

DOI： 10.4164/sptj.56.446

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Particle flowability can be improved by admixing particles smaller than the original particles (main particles). However, the mechanisms by which this technique improves flowability are not yet fully understood. In this study, we examined compressed packing in a particle bed, which is affected by particle flowability. To estimate the mechanism of improvement, we investigated the effects of the main particle diameter on the improvement of compressed packing fractions experimentally.
The main particles were 397 and 1460 nm in diameter and the admixed particles were 8, 21, 62, and 104 nm in diameter. The main and admixed particles were mixed in various mass ratios, and the corn-pressed packing fractions of the mixtures were measured. SEM images were used to analyze the coverage diameter and the surface coverage ratio of the admixed particles on the main particles. The main particle packing fraction was improved as the diameter ratio (=main particles/admixed particles) increased. This was explained by a linked rigid-3-bodies model with leverage. Furthermore, the actual surface coverage ratio at which the most improved packing fraction was obtained decreased with increasing main particle diameter. This was explained by the difference in the curvature of the main particle surface. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2017.07.004

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.4164/sptj.54.97

J-GLOBAL

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

One technique for improving particle flowability is the admixture of nano-particles to the main particles. However, the mechanisms by which this technique improves flowability are not yet fully understood. In this study we examined compressed packing, which is affected by particle flowability. In order to investigate the mechanism of improvement, discrete element method (DEM) simulation was used to investigate the effects of adhesion forces and rotations of admixed particles on packing fraction.
We conducted two types of calculations: (1) compressed packing behavior of a particle bed, and (2) particle behavior in a simple model of the relative motion of two of the main particles. The main and admixed particles were given diameters of 400 and 20 nm, respectively. The physical properties of the particles were set based on silica and glass materials. The Hamaker constant of the main particles was kept constant while that of the admixed particle was varied from 2 x 10(-27) to 1 x 10(-20) J. Simulations were also conducted both allowing and not allowing rotation of admixed particles.
In the packing behavior calculations, the results for the packing fraction of the main particles and the compression velocity exhibited peaks at a Hamaker constant of approximately 10(-23) J for the admixed particles under 43.8 Pa compression pressure, regardless of the degree of rotation of the admixed particles. This showed that rotation of the admixed particles was not the main reason for the improvement in main particle flowability, and this peak tendency was determined by the Hamaker constant of the admixed particles. In addition, an improvement in the particle flowability via different numbers of layers of admixed particles was explained using a linked rigid-3-bodies model. This implies that the improvement in the flowability is due to a decrease in the resistance of particle movement by changing the configuration to a linked rigid-3-bodies model. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2016.07.021

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Society of Powder Technology, Japan  

A new apparatus was developed for the evaluation of particle adhesiveness. This apparatus uses shear stress that is induced by pulling a rod across a compressed particle bed. The tested samples were spherical silica particles with number based median diameters of 0.4 and 2.8μm. <br>When the height of the particle bed ≥ 17.0mm and the length of the rod in the bed ≥ 11.5mm, the shear stresses obtained by this apparatus were independent of either values of the bed height or the length of the rod. Using the values of stress, the inter-particle shear forces were calculated. The calculated forces increased with packing fraction and reached asymptotic values. The order of the asymptotic values agreed with that of the theoretical values of van der Waals force. This would be because frictional forces are based on adhesive forces in the real contact area （not the apparent contact area） of the 2 bodies. Thus, the new apparatus could be used to evaluate particle adhesiveness reflecting van der Waals force.

DOI： 10.4164/sptj.53.386

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS INC  

Surface cleaning using high-speed air jet can be applied to cleaning of an object with concavo-convex shape. In such cases, the distance between the air jet nozzle and the surface becomes on the order of cm. An increase in the distance causes a decrease of the air velocity at the surface resulting in deterioration of the particle removal performance of the air jet. Therefore, a method to enhance removal efficiency is required. In this study, we investigated two methods for the enhancement of removal efficiency: one is to set a wire in the air flow and the other is to set two cylindrical rods. Although the wire set at the center of the jet flow deteriorates the removal efficiency, experimental results imply that the wire has a positive effect on the efficiency when it is set at a position where it does not interfere with the main flow of the jet. On the other hand, when two cylindrical rods are set at a theoretical periphery of the air jet, it shows clearly an enhancement in removal efficiency. This fact implies that the removal efficiency can be enhanced by controlling flow fluctuation by means of setting an obstacle.

DOI： 10.1080/02726351.2015.1060653

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

One of the techniques for a reduction in particle cohesiveness is the admixing of nano-particles. However, the mechanism of cohesiveness reduction has not yet been clarified. In this study we focused on a compressed packing fraction as one of the values reflecting the cohesiveness and flowability in a compressed particle flow. In order to estimate the mechanism of the reduction, the effects of an adhesive force of admixed particles on the packing fraction were investigated experimentally.In the experiments, silica particles with 397 and 8 nm diameters were used as the main and the admixed particles, respectively. The surfaces of the admixed particles were modified chemically in order to vary their adhesive force with maintaining morphological and mechanical characteristics.At more than 2.0% mixing mass ratios, the decreasing rate with increasing the mass ratio in net difference value of packing fraction for modified admixed particles was smaller than that for the raw particles. A calculation of the packing fraction of the admixed particles in the voids of main particles revealed that difference of the decreasing rates could be attributed to the difference of cohesivenesses between raw and modified admixed particles.The maximum packing fraction achieved by the modified admixed particles was lower than that achieved by the raw admixed particles. However, when a mixture of main and admixed particles was packed by tapping, the packing fraction with modified admixed particles was higher than that with raw admixed particles. This implied that the adequate adhesive force of admixed particles is different by the applied compression force value. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2015.01.014

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.4164/sptj.51.629

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.4164/sptj.51.635

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：SOC CHEMICAL ENG JAPAN  

A new apparatus was developed to evaluate the flowability of particles with poor flow behavior. This apparatus uses the phenomenon that particles drain from a particle-bed as stress on the bed is gradually increased. Samples employed were coarse particles with good flow behavior ( 133, 158, 306 mu m) and fine particles with poor flow behavior (1.6, 4.5, 32.9 mu m). The drained angles of coarse particles obtained with the new apparatus agree with those obtained with a conventional apparatus. Hence, the new apparatus is applicable for coarse particles. On the other hand, the drained angles of the fine particles could not be measured by the conventional method, as particles did not drain from the container. However, with the new apparatus, a particle-bed of fine particles (<= 4.5 mu m) suddenly collapsed drained at a certain level of applied stress. From this stress value, the forces acting between particles in the bed were calculated, and these forces agreed with those obtained with a direct shear tester. Thus, the new apparatus can also be used to estimate shear stress. Furthermore, the apparent drained angle is proposed as a new flow property for particles with poor flow behavior, and this allows the flowability of these particles to be evaluated.

DOI： 10.1252/kakoronbunshu.40.376

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Language：Japanese   Publishing type：Research paper (scientific journal)  

CiNii Article

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CiNii Article

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Society of Chemical Engineers, Japan  

A thickener-modeled dry dense medium separator using a gas-solid fluidized bed was developed in which materials of different specific gravity float or sink in the bed and can be withdrawn by overflow or underflow. This system is expected to allow high-speed separation and low-maintenance operation compared with a conventional dry dense medium separator, because there are no moving parts for withdrawing floats and sinks from the bed. The effects of overflow/underflow rate and sample feed rate on the performance of the separator were investigated using silica sand as a fluidized bed medium and 20-mm diameter spheres of various specific gravities as samples for separation. It was found that when the overflow/underflow rate was 0.44 or less, the float-sink boundary was smaller than when there was no overflow and no underflow, but float-sink sharpness was maintained. On the other hand, when the overflow/underflow rate was 0.64 or more, the float-sink boundary was similar to that in the case of no flow, but separation sharpness deteriorated. Furthermore, when the overflow/underflow rate was 0.44 and the feeding rate was 0.035 kg/s (=2.2 m³-object/(m²·h): volume-based separation speed per fluidized bed area) or less, Newton efficiencies were more than 0.9. Compared with conventional apparatus, the separation speed of the present apparatus was 3.4 times higher. Hence, this withdrawing system can be valuable for increasing separation speed and reducing the need for maintenance.

DOI： 10.1252/kakoronbunshu.39.178

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Other Link： https://jlc.jst.go.jp/DN/JALC/10018806020?from=CiNii

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP PUBLISHING LTD  

We investigated the release characteristics of single-wall carbon nanotubes (CNTs) synthesized by a pilot-scale plant. In addition to on-site aerosol measurements at the pilot-scale plant where the CNTs were synthesized, harvested, and packed, we conducted dustiness tests by vortex shaking and by transferring CNTs from one bowl to another. In the results of the on-site aerosol measurements, slight increases in the concentration were observed by aerosol monitoring instruments in the enclosure where CNTs were harvested and packed. In filter samples collected in this enclosure, micron-sized CNT clusters were observed by electron microscopy analysis. For samples collected outside the enclosure or during other processes, no CNTs were observed. The concentrations of elemental carbon at all locations were lower than the proposed occupational exposure limits of CNTs. The results of the dustiness tests revealed that submicron-sized particles were dominant in the number concentration measured by aerosol monitoring instruments, whereas micron-sized CNT clusters were mainly observed by electron microscopy analysis. The results of dustiness tests indicate that these CNTs have a low release characteristic. The lower drop impact of CNT clusters due to their lower bulk density resulted in lower CNT release from falling CNTs.

DOI： 10.1088/1742-6596/429/1/012057

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

One of the techniques used to decrease the cohesive force between particles is the admixing of nanoparticles. However, the optimal conditions that will produce a minimum amount of force have not been established. In this study, we investigated the effects of the agglomerated state and the gap of coverage for admixed particles on particle-bed packing fractions in uni-axial compression. The main particles were made up of 397 nm silica particles. The admixed particles included 8, 21,62 and 104 nm silica particles. The main and admixed particles were mixed using a mortar and pestle for 5 min for various mass ratios. SEM images were used to analyse the coverage diameter and the surface coverage ratio. As a result, the packing fractions with admixed particles of 8 and 21 nm were larger than when admixed particles were not used, and these admixed particles adhered onto the surface of the main particles as agglomerates. However, packing fractions of 62 and 104 nm were almost constant and were independent of the coverage states of admixed particles. Furthermore, these admixed particles with relatively larger diameters were adhered onto the surface as single particles. From the coverage diameter and actual surface coverage ratio obtained by the SEM image, the average gaps between agglomerates of 8 and 21 nm on the main particle were calculated. When the gap approached twice the size of the coverage diameter, packing fractions of 8 and 21 nm proved to be the maximum values. However, when the gap was less than the coverage diameter, the packing fractions deteriorated. (C) 2013 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2013.01.004

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.4164/sptj.49.810

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

In this study, the influence of the fluidized bed height on the float-sink of different sized spheres in a gas-solid fluidized bed was investigated. Fluidized beds with heights h = 200, 150, 100 and 50 mm were prepared using a cylindrical column of inner diameter = 290 mm and a mixture of zircon sand and iron powder as the fluidized medium. Float-sink experiments were carried out using density adjusted spheres of diameter D-sp = 40, 30, 20 and 10 mm. It was found that the float-sink performance at D-sp >= 20 mm is not affected by the height of the bed, and the sharpness of separation (the density range where spheres neither float nor sink completely) is less than or equal to 200 kg/m(3). In the case of D-sp = 10 mm, the sharpness of separation is a larger value (1100 kg/m(3) at h = 200 mm), whereas it decreases with decreasing h and is 400 kg/m(3) at h 50 mm. The fluctuation of the surface height of the fluidized bed was visually recorded. The fluctuation is reduced by reducing h. The fluctuation vs. h correlates with the sharpness of separation at D-sp = 10 mm vs. h. These results indicate that the dry float-sink separation of smaller sized spheres is improved as the fluctuation of fluidized bed surface is decreased by reducing the fluidized bed height. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2010.11.013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The float-sink of density adjusted spheres of different diameter (10-40 mm) in a gas-solid fluidized bed was investigated at various bed heights (50-200 mm). The maximum density of floating spheres (rho(float)) and the minimum density of sinking spheres (rho(sink)) were determined by the float-sink experiments. The fluidized bed density (rho(fb)) was measured using the height and cross section of the fluidized bed and total weight of the fluidized media. The diameter of air bubbles at the bed surface was measured at each bed height, and was normalized by the sphere diameter. It was found that the value of rho(fb)-rho(float) approaches zero as the normalized bubble diameter decreases from 4 to 0.5 regardless of the sphere diameter. The value of rho(sink)-rho(fb) for sphere diameter = 10 mm approaches zero as the normalized bubble diameter decreases from 4 to 1.5, whereas the value for sphere diameter = 20-40 mm rises from zero as the normalized bubble diameter decreases from 1.5 to 0.5. The float and sink of spheres basically tend to follow the fluidized bed density with decreasing the normalized bubble diameter. However, relatively larger spheres do not sink based on the density difference as the normalized bubble diameter decreases, which may be due to that the fluidized bed viscosity becomes larger as the normalized bed diameter decreases. (C) 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2011.08.002

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Amorphous calcium phosphate nanoparticles were synthesized by mixing aqueous solutions of Ca(NO3)(2) and (NH4)(2)-HPO4. Then the particles were matured with sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) at various temperatures. Rod-shaped hydroxyapatite (HAp) nanoparticles were formed at maturation temperature >= 40 degrees C. These results indicate that addition of AOT nor during the particles synthesis but during the maturation at more equal critical temperature is a key to form the rod-shaped HAp nanoparticles using AOT.

DOI： 10.1246/cl.2011.1085

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

We synthesized rod-shaped hydroxyapatite (HAp) nanoparticles using sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as an additive in water without an oil. The length of the particles increases from 40 to 100 nm with increasing the concentration ratio AOT/Ca while maintaining a width of 12 nm. These results indicate that an oil phase is not necessarily needed to form the rod-shaped HAp nanoparticles using AOT.

DOI： 10.1246/cl.2011.400

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Three kinds of particles with different hydrophilic and hydrophobic properties were used as fluidized particles of Fluidized Bed Medium Separation (FBMS). A minimum fluidization velocity, an apparent specific gravity of fluidized bed and floating-sinking behaviors of dry and wet coals were measured in the range of relative humidity from 50% to 80%. In a hydrophilic particle, the fluidization became unstable with increasing relative humidity because particle aggregation took place at a high humidity, and hence floating-sinking behaviors depend on changes in a relative humidity. On the other hand, in a highly hydrophobic particle, the fluidization was stable and floating-sinking behaviors based on the specific gravity difference were obtained even for wet coals and at a high relative humidity. Therefore, the FBMS using a highly hydrophobic particle is applicable at a high relative humidity without a control device of relative humidity. (C) 2010 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2010.10.008

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A gas-solid fluidized bed was used for dry dense medium separation of lump iron ore particles based on their floating and sinking in the fluidized bed. The density of the bed was adjusted to different values using mixtures of zircon sand and iron powder as the fluidized media. Float-sink experiments using 30 mm diameter density adjusted spheres in the range of 2100-4500 kg/m(3) in density increments of 100 kg/m(3) were carried out to determine the partition curves, the density of the bed and the probable error (Ep). It was found that the density could be adjusted in the range of 2500-4200 kg/m(3), when the bulk volume fraction of iron powder and the fluidizing air velocity were varied. The Ep values were less than or equal to 0.05, if suitable fluidizing air velocities were chosen. The density of the bed determined using the spheres floating-sinking corresponds to that measured using the height of the fluidized bed. The float-sink performance of lump iron ore particles in the size range of +25-31.5 mm agrees well with the spheres&apos; float-sink performance. The partition curves, separation density and the Ep values were determined for the lump iron ore particles. The Ep value for the ore particle separation was around 0.03. The theoretical Fe-grade recovery (washability) curve for the ore was determined for separation densities between 2500 and 4200 kg/m(3) from the density distribution and Fe content of the lump iron ore particles. The actual Fe-grade and recovery were calculated from the partition curves of the ore particle separation and compared to the theoretical maximum obtainable Fe-grade and recovery. (C) 2010 Published by Elsevier Ltd.

DOI： 10.1016/j.mineng.2010.10.010

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DOI： 10.1252/kakoronbunshu.37.317

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.4164/sptj.47.458

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The purpose of this study was to estimate the screening of electrostatic repulsions between the polar headgroups of AOT(-) by alkali metal counterions and to explore the relationships between the screening effect and the phase behavior of H-AOT-based W/O microemulsions. The screening effect was evaluated by means of critical micelle concentration (CIVIC) data using the pyrene 1:3 ratio method with aqueous Solutions containing M-AOT (where M(+) = Li(+), Na(+), K(+), Rb(+) and Cs(+)) to form normal micelles, and by counterion binding constants, determined from plots of CMC versus counterion concentration. The order of the screening effect was found to be K(+) approximate to Rb(+) > Cs(+) > Na(+) > Li(+). Interestingly, the order does not follow the hydration size dependence of the alkali metal counterions. An aqueous MOH Solution containing a given concentration/H-AOT/isooctane was emulsified at a water content (w(0) = [water]/[H-AOT]) of 10 to produce H-AOT-based W/O microemulsions. The phase behavior and size variation were investigated by FT-IR and DLS measurements. The emulsified mixture separates into two phases at lower MOH concentration due to all insufficient screening effect. When the concentration is increased to a level Sufficient to intensify the screening effect, W/O microemulsions are formed without phase separation at lower KOH and RbOH concentrations compared to CsOH. A period of standing after the emulsification and a higher concentration of NaOH compared to KOH, RbOH, and CsOH are required to form W/O microemulsions. W/O microemulsions are not formed ill the case of LiOH. These results indicate that the formation of a W/O microemulsion with H-AOT is strongly correlated with the order of the screening effect. A possible cause for the difference in the screening effect is proposed based oil hydration of the polar headgroups and counterions, as evidenced by FT-IR spectral data, i.e., symmetrical sulfonate stretching and O-H stretching.

DOI： 10.1021/la902700j

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.4164/sptj.47.92

CiNii Article

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

In order to decrease Cl content in waste plastics, dry density float-sink separation of Cl-contained and Cl-free plastics was explored using a semi-continuous rotating-type gas-solid fluidized bed separator with silica sand. The separator has two distinctive features: (I) the plastics can be fed at a middle height of the sand bed, and (2) when the plastics are recovered with the sand from a container after the float-sink, the recovery height of the sand bed can be changed to designate the plastics as floaters or sinkers. The waste plastics of Cl content = 5.4 wt% were used in this study. The separation was investigated by changing the experimental conditions. As a result, the float-sink of the plastics was affected by the air velocity for fluidization, the float-sink time and the feed amount of plastics. The possible causes of the effects were discussed by focusing on the apparent density of fluidized bed, the fluidization intensity, the size segregation of fluidized particle, the shape of the plastics, and the interactions between the plastics during the float-sink. When the recovery height was changed at the adjusted conditions, the Cl content in the floaters was successfully decreased to be 0.4-0.85 wt%, at which the recovery of the Cl-free plastics was 40-60%. (C) 2009 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2009.11.002

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

A method for dispersing dry particles in a liquid is described. The method involves coating large carrier particles with fine particles. When two types of particles having different sizes are mixed in dry conditions, the particles adhere to one another, and the large particles become coated with small particles. When the large core particles are coated with a mono-layer of small particles, further agglomeration is inhibited. Because the single small particles generated by the disruption adhere to the core particles, we presumed that, if the small particles that are adhered to large particles could be separated from the large particles by a sonication in a liquid, the dry fine particles could be dispersed in a liquid.
The dispersion experiments conducted using spherical silica particles having a count median diameter D(p50) of 74 nm as small particles and spherical glass beads as large particles. In this Situation, the large particles carry the small particles from a dry condition into a liquid. We refer to the large particles as carrier particles. The experiments revealed that the proposed dispersion procedure results in a superior product, compared to sonication only. The effect of carrier size on dispersion performance is also investigated. The findings indicate and an optimum carrier size exists. Observations of the carrier particle surfaces after dry mixing indicate that the optimum condition is the condition at which a mono-layer of Silica particles is formed. (C) 2009 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2009.10.004

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We investigated how the increase of NaOH concentration in the water pool affects the phase behavior and size of Na-AOT-based W/O microemulsions. A mixture of NaOH aqueous solution/Na-AOT/isooctane was emulsified by changing the NaOH concentration C(NaOH) at a water content w(0) = [water]/[AOT(-)] = 10. FT-IR measurements demonstrated that the amount of water in the upper phase of the emulsified mixtures decreases with increasing C(NaOH) to form a lower phase, whereas the amount of AOT- in the upper phase remains nearly constant. Substituting NaCl for NaOH resulted in the corresponding phase behavior, indicating that the phase separation is due to the increase of not pH but Na(+) concentration. Possible mechanism for the phase separation is discussed by focusing on screening effect of Na(+) counterions on electrostatic repulsions between AOT(-) polar headgroups. The apparent water content w(0)&apos;, estimated using the amount of water and AOT- in the upper phase, decreases with increasing C(NaOH). DLS measurement showed that the upper phase contains single-nanometer W/O microemulsions and the size decreases with increasing C(NaOH) with progress of the phase separation. Measurements of FT-IR and DLS were also carried out for W/O microemulsions prepared with pure water by changing the water content w(0). Wavenumber positions of hydroxyl and sulfonate groups were determined by FT-IR measurements. Interestingly, the dependence of wavenumber positions and size on w(0)&apos; agrees with those on w(0), which indicates that variation of W/O microemulsion&apos;s property with progress of the phase separation corresponds to the variation with decreasing the water content to prepare W/O microemulsions with pure water. (C) 2009 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2009.08.003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The objective of this study is to estimate the contribution of Na+ as a counterion in the formation of H-AOT&Na-AOT-based W/O microemulsions using aqueous NaOH solution by pyranine absorbance measurements. A mixture of an aqueous NaOH solution containing pyranine/H-AOT&Na-AOT/isooctane was emulsified by changing the mixing ratio of Na-AOT (XNa-AOT = 0-1) and the mole fraction of NaOH (X-NaOH = [NaOH]/the AOT(-) concentration in the water pool = 0-1). The phase behavior of the emulsified mixture was evaluated from the absorbance of pyranine at the isosbestic point and by visual observations. W/O microelumsions are formed at the mid-range Of XNa-AOT, whereas the emulsified mixture separates into two phases at lower XNa-AOT and higher XNa-AOT. The two phase boundaries shift toward lower XNa-AOT as with increasing X-NaOH. The phase behavior depends on the degree of screening of electrostatic repulsions between the polar headgroups of AOT(-) by the Na+ counterion. Interestingly, nano-sized W/O microemulsions are formed without phase separation using a highly concentrated NaOH aqueous solution when the Na-AOT mixing ratio is appropriately adjusted. The phase behavior was plotted as X-NaOH versus XNa-AOT, and the correlation equations for the two phase boundaries were obtained by fitting the points. The contribution of the Na+ counterion from NaOH to W/O microemulsion formation was estimated by the correlation equations. The absorbance of pyranine and the size of W/O microernulsions, as measured by DLS, were plotted as a function of XNa+ = (x[Na+ from NaOH] + [Na+ from Na-AOT])/[AOT(-)], in which x is the ratio contributed by NaOH. The absorbance and size correlates well with XNa+, indicating that XNa+ is a meaningful parameter for quantitatively estimating phase behavior and size variation. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2009.09.020

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Oil-in-water nanoemulsion which consisted of TEMPO, amphiphilic alcohols, and water offered unique reaction environments for electrooxidation of the alcohols to give the corresponding carboxylic acids in good to excellent yields. (c) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2009.06.005

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Society of Powder Technology, Japan  

In this study, float-sink of chlorine containing and not-containing plastics in a gas-solid fluidized bed of silica sand was studied with and without joints in the air distributor and by changing the amount of objects loaded on the air distributor. The float-sink was evaluated using three parameters, i.e., recovery, purity and efficiency. The values obtained with the joints are smaller than without the joints, and decreased with increasing the amount of objects on the distributor. Because there is no airflow at the joints, the sand on the joints is not fluidized and circulating flow of the sand is generated over the area other than the joints. A 2D fluidized bed showed that air bubbles are not uniformly generated on the air distributor and the fluidization of the sand becomes intense when the objects are on the distributor. These results indicate that the circulating flow and the sudden intense fluidization disturb the expected float-sink of objects.

DOI： 10.4164/sptj.46.206

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publisher：公益社団法人 化学工学会  

DOI： 10.11491/scej.2009.0.96.0

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The dependence of water pilot pH on the water content of the W/O microemulsions was investigated by using the absorhance ratio of pH-sensitive probe pyranine. The W/O microemulsions were prepared with a mixture of an aqueous solution of pH 1-13 containing pyranine, AOT and isooctane at w(0) = [water]/[AOT] = 10, 20, 30 and 40. The water pool pH was estimated by comparing the absorbance ratios given by the W/O microemulsion and the aqueous solutions of pH 1-13. The experimental results suggest that the water pool pH is kept approximately constant its it buffer regardless of the solution pH 4-11, and that the water pool pH increases with decreasing w(0). As all additive factor to affect the absorbance ratio of pyranine. high Na(+) counterion concentration in the water pool was focused oft because the roughly estimated Na(+) concentration increases front 1.4 to 5.6 M with decreasing w(0). It was found by the ratio measurements for NaOH aqueous solutions that the ratio increases at NaOH concentration &gt; 5 M, which suggests that the ratio given by the W/O microemulsions is affected by not only pit, but also high Na(+) concentration in the water pool. It would be correct to assume that the AOT-based W/O microemulsions play a role of the buffer, and that the water pool pH depends on w(0). However, attention should be paid to the possibility that the water pool fill estimated by the absorbance ratio of pyranine may include the effect of high Na(+) concentration in the water pool.

DOI： 10.1252/jcej.07we287

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Society of Powder Technology, Japan  

Removal of single particles adhering on a flat plate by a high-speed air jet has been investigated experimentally. Although jet nozzle or removal target is scanned in an industrial application of the air jet removal, almost all previous fundamental investigations for the air jet removal were carried out with a fixed nozzle and a fixed target. Therefore, we aimed at elucidating how the scanning speed of target flat plate affects the removal efficiency.<br>Experimental results showed that the removal efficiencies at a constant air pressure of the nozzle decreased with an increase in the scanning speed of the target plate. With an increase in the scanning speed, the residence time of adhered particles in the effective jet exposure area is decreased. Therefore, the decrease in the removal efficiency with an increase of the scanning speed is caused mainly by a decrease in the residence time in the impinging air jet. It was also found that the effective area can be estimated by the equation of stable removal region on a fixed target.

DOI： 10.4164/sptj.45.690

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DOI： 10.4164/sptj.45.297

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Formation of iron oxide particles with aerosol-OT (AOT)/isooctane/water emulsion was carried out employing a coprecipitation reaction for Fe 3O4 particles. Emulsions containing Fe2+/ Fe3+ were mixed with those containing OH-. Iron oxide particles were formed by changing the concentration ratio of AOT to iron ions and maintaining the volume fraction of water in the emulsion at 0.25. Particle formation was also carried out using nonemulsified aqueous solutions as a reference. The morphology, crystal structure, magnetic property and hydration degree of the particles formed under various conditions were compared. The α-FeOOH or amorphous particles are formed instead of Fe3O 4 when the AOT concentration is comparable to, or higher than, the iron ion concentration. These particles contain an OH group and water, and are oxidized to become α-Fe2O3 by heating in N 2. The Fe-AOT complex as the origin of OH-rich particle formation was the focus of this investigation. The IR measurement was carried out for the Fe-AOT complex, separately prepared with the aqueous solution. It was found that the Fe-AOT complex was hydrated, indicating that hydration of the complex affects the properties of particles formed by the emulsion. A possible mechanism for formation of α-FeOOH or amorphous particles with emulsion is proposed. © 2008 Curtin University of Technology and John Wiley &amp
Sons, Ltd.

DOI： 10.1002/apj.143

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEORG THIEME VERLAG KG  

Oil-in-water nanoemulsions, consisting of TEMPO, amphiphilic alcohols, and water, offer unique reaction environments for electrooxidation of the alcohols to give the corresponding carboxylic acids in good to excellent yields.

DOI： 10.1055/s-2007-991070

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DOI： 10.4164/sptj.43.882

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Society of Powder Technology, Japan  

Fluidized bed medium separation (FBMS) was applied to separate objects with a small specific gravity difference by precisely controlling the apparent specific gravity of gas-solid fluidized bed with binary particle systems. The binary systems of particles with various specific gravities and diameters were employed, and the apparent specific gravity of fluidized bed, g_fb and the dispersion, Δg_fb, were measured by changing the bulk volume fraction of heavier particle, V_hp, and the superficial air velocity, u₀. It was found that g_fb can be controlled by V_hp and u₀ because g_fb varies with the total mass of particles and the bed expansion. On the other hand, since Δg_fb is determined by the extent of segregation of fluidized particles and the fluidization intensity, Δg_fb decreases with reducing the extent of the segregation and the vertical fluctuation of fluidized bed surface. The experimental results showed that practical fluidized conditions for FBMS are in the range of g_fb≈0.5-3.8 and Δg_fb≤0.1. Under these fluidized conditions, plastics with a small difference in specific gravity (0.04-0.24) were almost completely separated at the top and the bottom of the fluidized bed.

DOI： 10.4164/sptj.43.567

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DOI： 10.4164/sptj.43.260

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Three kinds of particles with different hydrophilic and hydrophobic properties were used as fluidized particles of Fluidized Bed Medium Separation (FBMS). Minimum fluidization velocity, apparent specific gravity of fluidized bed and floating-sinking behaviors of dry and wet coals were measured in order to investigate the stability of fluidization by changing relative humidity of air flow introduced from the bottom of the fluidized bed. The fluidization of hydrophilic particles became unstable with increasing the relative humidity, because particle aggregation took place at a high humidity. On the other hand, the fluidization of highly hydrophobic particles was stable with wet coals even at a high humidity. Therefore, the FBMS with highly hydrophobic particles is applicable to the density separation of coals at a high relative humidity without a control device for the relative humidity.

DOI： 10.4164/sptj.43.252

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Fluidized bed medium separation (FBMS) was applied for gravity separation of plastics containing or not Cl for recycle of home electric appliance shredder residue. We employed mixtures of glass beads (G.B.) and polystyrene particles (PS.) with various mixing ratios as fluidizing particles. Floating and sinking of the plastics were examined by changing the bulk volume fraction and the superficial velocity u(o). The plastics were almost completely separated at the conditions of G.B.: P.S.=8: 2 and u(o)/u(mf) = 1.5 where u(mf) is the minimum fluidization velocity. Similar experiments were carried out by changing dimensional parameters of plastics, such as equivalent volume diameter D-v, flatness ratio R-f and aspect ratio R-a. As a result, it was found that influence of D-v on float-sink behavior was the highest and contribution ratio of D-v was about 75%.

DOI： 10.1252/kakoronbunshu.32.115

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DOI： 10.1299/kikaic.71.2321

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Fluid penetration method is applied in order to evaluate the non-uniformity of a particle bed structure. The apparatus developed consists of a cubic sample box which can be set on either surface. The pressure drops across the packed bed in the packing direction and its perpendicular direction were measured. The fluid penetration resistance in gravitational direction (=packing direction) was higher than that in the perpendicular direction, and the difference depended on the particle size and shape.<br>In order to find the relationship between the differences and the orientation of particles to the packing direction in a packed bed, experiments were conducted using a model packed bed consisting of uniform cylinders with a diameter of 4mm and a length of 100mm. A correlation was obtained between the orientation angle of cylinder axis to the packing direction and the ratio of specific surface area in perpendicular direction to that in the gravitational direction which were determined by the pressure drop measurements. Non-uniformity of a packed bed structure can be evaluated with the orientation angle to the packing direction using the obtained correlation.

DOI： 10.4164/sptj.42.613

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We studied the behavior of particles in the thermal convective flow field induced by heating and cooling of opposed vertical walls experimentally. The object is the effect of the circulating convection on a particle behavior during sedimentation or floatation. Visualization of particle behavior revealed that the thermal convective flow segregated the particle into the hot wall side, resulting in the local re-circulation of particles along the hot wall when the particle density is higher than that of fluid, while the flow segregated the particle into the cold wall side when the particle density is lower than that of the fluid. These segregations are center symmetrical when the absolute values of density differences are the same. In order to investigate the main cause of the segregation, we simulated the particle trajectories in two types of circulating flow: (i) thermal convection and (ii) simple circulation induced by shear. By comparing the particle trajectories in these two flow fields, it was found that the circulating fluid motion causes the segregation, but the thermal convection enhances the segregation. The enhancement must be attributed by the distribution of fluid properties induced by the temperature distribution.

DOI： 10.1163/1568552042000237

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Society of Chemical Engineers  

The effect of fuel particle shape on the combustion front propagation rate of the reverse combustion in a packed bed was studied experimentally. We used shredded rectangular papers having different aspect ratio and size as model particles. Our discussion focuses on the combustion in which the surface reaction is dominant. Experimental results showed that the combustion front propagation rates under constant gas velocity depended on the particle shape, but had no correlation with geometric parameters such as length, area and aspect ratio. We presumed that the difference in propagation rate depending on the particle shape was attributable to the difference in effective surface area in the surface reaction. Then, we estimated the effective specific surface area through the permeability method. It was found that the combustion front propagation rates at consrtant gas velocity increased with the effective specific surface area. This fact implies that the effective specific surface are are presents the difference in surface reaction rates dominating the combustion propagation rate under our experimental conditions. Furthermore, we estimated the mass transfer coefficient by means of analogy of j-factor. In the estimation, we defined the effective equivalent diameter calculated from the effective specific surface area as the representative length of the fuel particle. As a result, it was found that the propagation rate correlated with the mass transfer coefficient estimated by the effective equivalent diameter, independently of the particle size, shape and gas velocity. This fact shows that the effect of the particle shape on the combustion front propagation rate in a reverse combustion process of a packed bed can be evaluated by the permeability method.

DOI： 10.1252/kakoronbunshu.29.500

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Society of Powder Technology, Japan  

The effect of fuel particle shape on the reverse combustion process of a packed bed was investigated through the comparison of combustion of spherical-particle packed bed and non-spherical particle bed. In the experiment, we measured the combustion propagation rate at various superficial gas velocties by using the spherical and non-spherical granular activated carbon particles consisting of the same primary particles. Experimental results showed that the propagation rate of non-spherical particles was higher than that of spherical particles with the same diameter measured by sieves and that the rate of smaller particles was higher than that of larger particles. The combustion propagation rates were well correlated by the equivalent specific surface area obtatined by penetration method. This implies that the effect of particle shape on the reverse combustion of packed bed can be estimated by the penetration method.

DOI： 10.4164/sptj.39.743

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Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

The effect of orientation of chain-like agglomerated particles on the pressure drop has been studied experimentally by using the electro-rheological fluid. By means of two types of test sections generating the electric fields perpendicular (= cross flow type) and parallel (= parallel flow type) to the flow, increments of pressure drop by the agglomerations were measured. The obtained pressure drop increment by the cross flow type was almost 3 times higher than that by the parallel type when the concentration of particles, fluid Reynolds number and electric field intensity were the same. In order to explain the main cause of the agglomerations orientation, we proposed a model in which the pressure drop induced by the agglomeration is assumed to be equivalent to the energy consumption by the breakage of the chain-like agglomeration in the unit volume. Based on this model, the ratio of the increment of the pressure drop of the cross flow type to that of the parallel flow can be deduced as the ratio of the numbers of agglomerations. The number of the agglomerations was estimated by the force balance between the adhesive force of the particles and the drag force induced by the flow through the fibrous layer. In the force balance, we took into consideration the effect of the orientation of the force. This model could explain the effect qualitatively. This fact implies that the effect of orientation can be considered as the effect on the drag force of fibrous agglomeration layer and the force direction, depending on the agglomerations orientation.

DOI： 10.1299/kikaib.68.2036

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Society of Chemical Engineers, Japan  

The effects of fuel particle size on the combustion propagation rate of the reverse combustion in a packed bed were studied experimentally. We used spherical pellets of activated carbon having a size range of 2.8~6.7 mm. Superficial air velocity was set in the range of 0.012-0.165 m/s. The experimental results showed that in the lower gas velocity region, the combustion front propagation rate increased with the air velocity independently of the particle size. However, at air velocity beyond a certain value, the propagation rate took an asymptotic value that increased with decrease in the particle size.

DOI： 10.1252/kakoronbunshu.28.227

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Annular jet-type virtual impactor was developed and tested with the use of an industrial powder. The new virtual impactor was designed based on an impactor having a rectangular jet. It was expected that the new impactor has a superior performance compared to the impactor with a rectangular jet because the annular jet has no end, which causes the deterioration of the performance. The classification experiments, however, showed lower performance than expected. Observation of the deposited pattern of the classified particles revealed that the flow was asymmetric, i.e. the flow had a three-dimensional structure in azimuthal direction. Therefore, the collection nozzle was improved so as to divide the classification zone into four parts and to accelerate the flow in each part. As a result of the improvement. 50% cut-size of the annular-type virtual impactor was well-fit to the theoretical value and the separation efficiency at the diameter smaller than 50% cut-size was close to the theoretical curve.
However, the separation efficiency at the diameter larger than 50% cut-size was unchanged. From the comparison of configurations of the impactors used in a previous work and in this work. we presume that the shape of the nozzle collecting a finer aerosol affects the classification performance. In order to confirm the prediction, classification experiments were carried out by small-scale rectangular jet virtual impactors having different nozzle angles. The results revealed that the smaller nozzle angle deteriorates the classification performance even for the same configuration of the classification zone. The result implies that the performance of the annular-type virtual impactor can further be improved if the nozzle shape is properly designed. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0032-5910(01)00296-0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

A two-layer, salt-stratified NaCl-H2O system destabilized and mixed by lateral heating and cooling is considered in this paper. Flow visualizations are performed to examine the structure of the diffusive interface that separates the convection layers. Simultaneous temperature measurement and flow visualization technique reveal the existence of a regular, three-dimensional flow structure consisting of time-periodic buoyant plumes within the interface, which are due to instabilities of diffusive type. The plumes aligned in the spanwise direction travel toward the hot wall above the interface and toward the cold wall below the interface, respectively, and there is a phase shift of a half plume spacing between the upper and lower ones. Consequently, temperature and concentration oscillations are periodically observed in the paths of plumes. (C) 2000 American Institute of Physics. [S1070-6631(00)50511-X].

DOI： 10.1063/1.1308511

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DOI： 10.1080/027868200303759

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DOI： 10.1016/S0921-8831(08)60447-1

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Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Association of Aerosol Science and Technology  

Removal of deposited single particles by use of a vibrating air jet has been studied experimentally, with particular attention to the effect of operating conditions. Two types of nozzle were newly designed and 6 sorts of metal plates were used as a vibrating plate. Twelve combinations of the nozzle and the vibrating plate have been tested to get the best combination for the generation of a high frequency vibration. Experimental results showed that the removal efficiency is almost determined by the vibration characteristics rather than air jet velocity. When the nozzle pressure is set at 2.5&times;10⁵ Pa or 3.0&times;10⁵ Pa, the removal efficiency tends to increase with the frequency of the vibration at the surface. In this case, longer jet duration time enhances the efficiency. Then, the number of repetition of pressure pulsation is one of the main cause of the effects of vibration. On the other hand, when the pressure is set at 3.5&times;10⁵ Pa, the removal efficiency is affected by the shape of the vibrating wave.

DOI： 10.11203/jar.13.133

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Language：Japanese   Publisher：The Society of Chemical Engineers, Japan  

'Size segregation' is a typical phenomenon usually accompanied with flow of particles. It has been demonstrated experimentally and macroscopically. However, the microscopic mechanism is difficult to observe, and it is not understood sufficiently. In this study, the experiment focused on size segregation simulated using the distinct element method. A 2-dimensional simulation for the full model of the experiment indicates equivalent behavior. However, size segregation in an accumulated layer is not properly shown. Next, the simple partial model is simulated using 2-and 3-dimensional analysis. The 2-D result does not show the size segregation clearly due to the wide scattering of data, but that of 3-D shows that it is possible to simulate the segregation properly. Also, detailed observation of the movement of each particle demonstrates the validity of the mechanism of size segregation which was presented from the experiment.

DOI： 10.1252/kakoronbunshu.22.622

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DOI： 10.1016/0927-7757(95)03471-4

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Society of Powder Technology, Japan  

The size segregation of polydispersed particles stored in a container was studied experimentally by tapping varying the number of taps and the falling height of the container. Tested particles ranged from 150-600μm in size.<br>It was found that the smaller particles were concentrated at the vicinity of the container bottom, while larger particles were concentrated at the upper-side. The mass median diameter (MMD) of the particles concentrated along the container bottom became smaller as the number of tapping increased and converged to a certain value. The deviation of this value from the MMD of the feed-particles was almost proportional to the square root of the falling height. This fact showed that the deviation in MMD was related to the impact force of particles which was induced by the tapping.<br>Visualization of particle movement was also carried out by the use of colored particles. It was found that the particle recirculation was induced in the container by the tapping; i. e. at the center of the container, particles were rising from the bottom to the surface of the particle-layer, while particles were dropping in the vicinity of the periphery where smaller particles moved down faster than larger particles. On the other hand, larger particles moved faster than smaller particles from the periphery to the center. Thus, it was confirmed that such differences in the movement between larger and smaller particles caused the vertical size segregation of the particles in the container.

DOI： 10.4164/sptj.32.89

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DOI： 10.1252/kakoronbunshu.20.685

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Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Society of Chemical Engineers, Japan  

Removal of particles adhering to a surface was studied, using a high-speed air jet with particular attention to the effect of particle diameter. The experiment was conducted for latex particles of 110 μm diameter adhering to a surface of glass (flat surface), metal or plastics under various pressures in the air jet nozzle.<BR>The experimental results obtained with the flat glass surface revealed that the dynamic pressure for attaining 50% removal (P_d50) of particles was inversely proportional to the 2nd power of particle diameter. Variation of the dynamic pressure P_d50by the surface materials was well correlated with the surface characteristics (Hamaker's constant and elastic property) and relative surface roughness defined by the ratio of particle diameter and the curvature of surface protrusion. The removal force of the air jet was found to be proportional to the 2nd power of the dynamic pressure and to the 6th power of the particle diameter.

DOI： 10.1252/kakoronbunshu.20.693

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：VSP BV  

The performance of the mixer-type disperse has been studied experimentally with particular attention to the effect of the height of the vessel and the length of the inlet tube. The measurement of the particle residence time revealed that the vertical velocity component of the flow in the double-walled section constructed by the vessel and the inlet tube has a constant value. The short cut of particles from the inlet tube to the outlet tube occurred at the space between the inlet tube and the impeller. The experimental results of the newly designed dispers revealed that the double-walled section and the space below the inlet tube caused deterioration of the dispersion performance. The double-walled section caused the agglomeration of the dispersed particles. On the other hand, the space below the inlet tube caused the particle short cut from inlet to outlet resulting in the discharge of agglomerated particles without experiencing the dispersing action.

DOI： 10.1016/S0921-8831(08)60750-5

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：粉体工学会  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Association of Aerosol Science and Technology  

The classification performance of an improved rectangular jet virtual impactor having clean air entrances has been studied with particular attention to the effect of acceleration distance. Experimental results showed when the acceleration distance was shorter than a certain value, the classification performance became extremely worse. Flow visualization revealed this performance deterioration was attributed to the distortion in the flow field. Experimental results obtained under no flow distortion showed that longer acceleration distance caused a lower classification performance in the low inertia region because of particle diffusion, whereas shorter distance gave a lower performance in the high inertia region. However, it was found that the deterioration in the classification performance could be avoided if the partition plate for the wall side clean air entrance was set at shorter distance from the jet and that for the slit side clean air entrance was set at relatively longer distance.

DOI： 10.11203/jar.3.212

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Language：Japanese   Publisher：JAPAN ASSOC AEROSOL SCI & TECHNOLOGY  

There is growing concern about the potential impact of nanomaterials on human health. A significant exposure route is inhalation during manufacture and handling. Information on airborne nanomaterials, such as the magnitude of release, size distribution, and morphology, is required to evaluate and control nanomaterial exposure. In this study, dustiness testing of nanomaterials was conducted by the vortex shaker method. Aerosol particles released during agitation by passing air were measured by aerosol measurement instruments.

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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Language：Japanese  

CiNii Article

CiNii Books

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：HOSOKAWA POWDER TECHNOL FOUNDATION  

Fluidized bed medium separation (FBMS) was applied to separate objects with a small specific gravity difference by precisely controlling the apparent specific gravity of gas-solid fluidized bed with binary particle systems. The binary systems of particles with various specific gravities and diameters were employed, and the apparent specific gravity of fluidized bed, g(fb), and fluctuation, Delta g(fb), were measured by changing the volume mixing rati of heavier particle, V-hp, and the superficial air velocity, u(0). It was found that g(fb) can be controlled by V-hp and u(0) because g(fb) varies with the total mass of particles and bed expansion. On the other hand, since Delta g(fb) is determined by the extent of segregation of fluidized particles and fluidization intensity, Delta g(fb) decreases with reducing the extent of the segregation and the vertical fluctuation of fluidized bed surface. The experimental results showed that practical fluidized conditions for FBMS are in the wide range of g(fb) approximate to 0.5 similar to 3.8 and Delta g(fb) &lt;= about 0.1. Under these fluidized conditions, plastics with a small difference in specific gravity (0.04 similar to 0.24) were almost completely separated at the top and bottom of the fluidized bed.

DOI： 10.14356/kona.2008020

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：HOSOKAWA POWDER TECHNOL FOUNDATION  

Based on the fluid penetration, an evaluation method of the non-uniformity of a particle bed structure was developed. The newly developed apparatus has a cubic sample box that can be set at any direction. Pressure drops through the packed bed in the same direction as the packing direction and the cross direction of that were measured in the apparatus. It was found that the fluid penetration resistance in gravitational direction (=packing direction) was higher than that in cross direction to gravity. The differences between them depend on the particle size and shape.
In order to represent the differences as the apparent alignment of packed bed structure, the experiments using the model packed bed constructed by uniform circular bars having a diameter of 4mm were conducted. Through the experiments, correlation between aligned angle and the ratio of specific surface area of the cross direction to that in the gravitational direction was obtained. By means of the correlation, the non-uniformity of the packed bed structure can be evaluated as the apparent aligned angle.

DOI： 10.14356/kona.2007026

Web of Science

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Language：Japanese  

CiNii Article

CiNii Books

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Authorship：Lead author   Language：Japanese  

CiNii Article

CiNii Books

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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Event date： 2017.7.30 - 2017.8.3

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2016.3.28 - 2016.4.1

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Phoenix, Arizona, USA  

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Event date： 2015.9.15 - 2015.9.18

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2015.9.15 - 2015.9.18

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2015.7.7 - 2015.7.10

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2015.6.24 - 2015.6.27

Language：English   Presentation type：Poster presentation  

Venue：Kanazawa, Japan  

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Event date： 2013

Language：English  

We investigated the release characteristics of single-wall carbon nanotubes (CNTs) synthesized by a pilot-scale plant. In addition to on-site aerosol measurements at the pilot-scale plant where the CNTs were synthesized, harvested, and packed, we conducted dustiness tests by vortex shaking and by transferring CNTs from one bowl to another. In the results of the on-site aerosol measurements, slight increases in the concentration were observed by aerosol monitoring instruments in the enclosure where CNTs were harvested and packed. In filter samples collected in this enclosure, micron-sized CNT clusters were observed by electron microscopy analysis. For samples collected outside the enclosure or during other processes, no CNTs were observed. The concentrations of elemental carbon at all locations were lower than the proposed occupational exposure limits of CNTs. The results of the dustiness tests revealed that submicron-sized particles were dominant in the number concentration measured by aerosol monitoring instruments, whereas micron-sized CNT clusters were mainly observed by electron microscopy analysis. The results of dustiness tests indicate that these CNTs have a low release characteristic. The lower drop impact of CNT clusters due to their lower bulk density resulted in lower CNT release from falling CNTs.

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Event date： 2012.7.2 - 2012.7.5

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2010.4

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2007.9.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Beijing, China  

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Event date： 2007.9

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2005.11

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2004.10

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2004.10

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2003.12.17 - 2003.12.19

Language：English   Presentation type：Oral presentation (general)  

Venue：Peneng, Malaysia  

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Event date： 2002.9

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2001.9

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2001.6.24 - 2001.6.27

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2000.10.1 - 2000.10.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Kobe, Japan  

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Event date： 2000.9.8 - 2000.9.13

Language：English   Presentation type：Oral presentation (general)  

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Event date： 1999.5.16 - 1999.5.19

Language：English   Presentation type：Oral presentation (general)  

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Event date： 1998.9

Language：English   Presentation type：Oral presentation (general)  

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Event date： 1998.9

Language：English   Presentation type：Oral presentation (general)  

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Event date： 1998.8

Language：English   Presentation type：Oral presentation (general)  

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Event date： 1997.9

Language：English   Presentation type：Oral presentation (general)  

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Event date： 1995.9

Language：English   Presentation type：Oral presentation (general)  

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Event date： 1995.9

Language：English   Presentation type：Oral presentation (general)  

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Event date： 1994.8

Language：English   Presentation type：Oral presentation (general)  

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Event date： 1990.9

Language：English   Presentation type：Oral presentation (general)  

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