In various fields, most raw materials are in a granular state: their bulk properties are therefore of interest. The discrete element method (DEM) is frequently used to determine these properties. As numerous particles can be simulated by DEM, and particle shapes affect bulk properties, effective modeling of realistic particle shapes is required. In this study, two types of DEM simulations were compared: one using real ore particle shape, and one using particle shape computed by spherical harmonic-based principal component analysis. We confirmed the latter to successfully reproduce the bulk properties (repose angle, porosity, and coordination number) of the former.

Hematite (α-Fe₂O₃) nanoparticles were synthesized by a solvent-free homogeneous precipitation method using urea hydrolysis via dry mechanical treatment of urea and ferric nitrate nonahydrate for activation. This novel method consists of high-energy ball milling of the raw materials and subsequent heating of the activated liquid precursor, which can provide smaller-sized nanoparticles than conventional methods. The milling and heating conditions were systematically investigated in detail. It was found that the hematite formation can be promoted by milling ferric nitrate nonahydrate and urea simultaneously under dry conditions even when relatively gentle milling and heating treatments were employed. The hematite nanoparticles had a similar crystallite size and particle diameter regardless of the conditions. This method can contribute to large-scale environmentally-friendly synthesis of fine hematite nanoparticles.

Xylitol raw powder exhibits strong aggregation during storage, making it difficult to form fluidized bed and low compressibility. In this study, fluidized bed could be formed by co-milled with xylitol and fumed silica, and tabletability could also be improved by granulation with hydroxypropyl cellulose (HPC-L). To further improve the compressibility of xylitol, cellulose nanofiber (CN) was applied as a binder. As methods for adding CN, we investigated 1-step granulation method in which CN were added to the HPC-L binder solution and 2-step granulation method in which cellulose nanofibers are sprayed onto xylitol granules. In the 1-Step method, there was an optimum amount of CN. Addition of excess CN caused troubles during granulation and decreased the compressibility. In the 2-step method, the surfaces of xylitol granules were coated with CN. As a result, compressibility of the xylitol granules could be improved by only slight addition (13 ppm in xylitol) of CN.

The Mahalanobis-Taguchi system (MTS) is one of the multi-variate analyses which can classify data by correlations among multi-variables. The MTS has significant advantage of applying a cause analysis which provides effective variable combinations to upgrade the accuracy of the classification. In this study, droppings, which were extruded from Japanese rhinoceros beetle larva were selected to classify into male/female based on their shape-related features using the MTS. Based on the cause analysis, the projected area/Feret’s diameter (A/F) and solidity were the best variable combination which all the larval droppings were classified into male/female. Both the variable has surface roughness-related factors with size effect (A/F) without size effect (solidity). The MTS has the great ability to classify from the powders’ minor difference and will be an effective tool for particle design in the near future.

Wheel sliding, which may occur during rainy weather, is a severe problem faced by railways. The re-adhesion control method is an effective countermeasure; however, it cannot entirely prevent wheel sliding. Therefore, an increasing number of rail vehicles are equipped with a device that jets a small amount of ceramic particles toward the contact area between the wheel and rail to improve the wheel adhesion. However, no method exists to monitor the flow state of the particles in the jetting device. Therefore, we developed monitoring methods focusing on the electrostatic charging of particles passing through the device and conducted experiments using corundum and silica sands. The experimental results verified that two methods, that is, those used to analyze the electrical signals detected by the device and their integration values, are adequate to discriminate the flow state. Furthermore, we evaluated the electrostatic characteristics of the monitoring system and considered it for practical applications.

While the Discrete Element Method (DEM) is expected to evaluate wet grinding performance of bead mills, the conventional DEM requires high computational cost because it has the limitation of the time step size for stable computation. In addition, the simulation of wet grinding process requires additional cost to consider the interaction between beads and fluids by using such as CFD-DEM coupling techniques. This study proposes an analysis system for evaluating wet grinding performance of bead mills with less computational cost. Our proposed system adopts the Impulse-Based DEM (IB-DEM) which can use large time step size, the wall model by using the Sign Distance Function (SDF) which flexibly represents complicated shape walls, and the simple modeling of fluid force which can reduce computational cost. We verify our proposed system by comparing the numerical results with experimental results of bead mills with different shapes of rotors.

Continuous crystallization is the next step of manufacturing especially at the production of pharmaceutical ingredients. We have developed small-scale continuous taylor-vortex crystallizer that is suitable for research in laboratory. But there was a problem that rotating inner cylinder at high-speed range causes much frictional heat and it raises the temperature of the solution, that may spoil the effort of controlling characteristics of crystals. So, we have developed new taylor-vortex crystallizer that has inner cooling system. We conducted several examinations of anti-solvent crystallization of glycine, which aims to obtain unstable crystal polymorph of glycine continuously. The new crystallizer showed the advantage of crystallizing unstable crystal polymorph.

The ABC powder used for a fire extinguisher shows high flowability. The evaluation about a flowability of such powder was very difficult and was not able to show the difference in the property by the measurement of the existing repose angle. Then, in this study, we considered about a new evaluation method of the powdery flowability indicating the high flowability using ABC powder. That rotated a cylindrical container after the tapping, and an angle when powder collapsed was measured and was named the rotational collapse angle. As a result, the rotational collapse angle was able to clarify a flowable difference for high flowable powders such as the ABC powder. Furthermore, it was found that the rotational collapse angle could determine with the right and wrong of the emission test of the fire extinguisher beforehand.

Mechanical synthesis of lithium titanate hydrate (LHTO: Li_1.81H_0.19Ti₂O₅·xH₂O) in liquid phase was investigated using a bead mill. LHTO has layered crystal structure which leads to form thin plate particles. As starting materials, lithium hydroxide which was dissolved in water and titanium dioxide nanoparticles were used. As bead media, 0.3, 0.5 and 1 mm diameter of zirconia balls were employed. At least some amount of LHTO was formed at each bead size condition. In cases of 0.3 and 0.5 mm beads, crystallization of LHTO looked not to proceed after some hours. After 5 hours, the most crystallized LHTO was synthesized at 1 mm beads. Some of observed particles showed thin plate shape but the greater part of particles were fine particles in the obtained powder. It was supposed that synthesized LHTO particles were broken faster than crystals of LHTO grew up since small bead media performed high grinding ability.

A granular soil conditioner with several millimeter diameters was prepared using scallop shell powder by pan granulator. The scallop shell powder was classified using a vibrating sieve to adjust the angle of repose for the granulation. As a result, the scallop shell granules with controlled size were prepared by adjusting the process parameters of the granulation such as the pan angle and the rotational speed. In addition, the amount of lignin (binder for the granulation) was adjusted to be 4 wt.% to attain the enough strength for the assumed compressive stress during the storage. Lastly the acidity correction of the obtained scallop shell granules had a low immediate effect and a high persistence compared with that of the scallop shell powder.

This paper describes separation performance of newly developed forward cyclones with 7 kinds of size and structure. The forward cyclones have 2 or 4 tangential-air-inlets, a dust pot and a flow receiver for fine particles. Our previous study showed that the cyclones had sharp size separation performance for PM_2.5 but did not clarify the mechanism. Size separation characteristics of the cyclones were evaluated using a pair of optical particle counters with test aerosols of standard polystyrene latex particles ranging from 1 to 6 μm in diameter. Also swirling flow in the cyclone was observed by tracer powder. Measured data, such as 50% cut-off aerodynamic diameter at flow conditions of each cyclone, were used to estimate the flowrate branching off the dust pot. Ranging from 3 to 30 percent of total flowrate were passed to the dust pot before flow throughout the cyclone. The flow caused sharp centrifugal separation to the aerosol particles introduced into the cyclone. Smallest the cyclone (bore diameter was 10 mm) covered samplings for PM_2.5 fraction of ambient aerosols at 3 L/min and respirable particle faction (PM₄) at work environments at 1.7 L/‍min. Largest the cyclone (bore diameter was 90 mm) fitted to a high-volume air sampler of which flowrate ranged from 150 to 600 L/min, showed the same performance as the smallest one.

The sustained-release formulations consist of many components, such as the active pharmaceutical ingredient, excipient, binder, lubricant, and polymer, leading to the complex dissolution process. The objective of this study is the elucidation of the rate-determining step in the dissolution process by direct optical observation. The composite particles of hydroxypropyl methylcellulose (HPMC) and brilliant blue FCF (model drug) were prepared, and the direct observation of the dissolution process and image analysis were conducted. The decrease in particle size and the penetration of solvent into the particles during the dissolution process had little impact on the sustained-release performance. On the other hand, the diffusion rate of the model drug in the HPMC gel strongly depended on the type of HPMC, suggesting that the rate-determining step in the dissolution process of the sustained-release formulations using HPMC would be the drug diffusion process in the polymer gel in the particles.

In the field of non-equilibrium science, the Liesegang phenomenon is well-known as a particle formation process involving the diffusion of precursor chemicals. From a chemical engineering perspective, our research group had previously applied this method to synthesize metal nanoparticles and found that when Au ions diffuse unidirectionally into a gel containing a reductant, bands of Au nanoparticles are formed in a striped pattern. However, metal species other than Au have not yet been investigated. In this study, we synthesized nanoparticles of other metal species (Pt and Pd) using a similar process and compared the results with those of the Au nanoparticles to clarify the particle formation mechanism. The findings showed that the band patterns that were formed vary according to the metal species. Furthermore, the bands formed in each metal species were reproduced by using a mathematical model capable of representing the diffusion of ions and the formation of particles.

Currently, slurry coating is used in the manufacturing process of various products such as electrode films for batteries, electronic materials, and optical materials. However, it is well known that the distribution of material composition in the electrode film has a significant impact on the performance of the device. A slurry is a mixture of powders, binders, and additives dispersed in a liquid, and when this mixture is coated and deposited, the mixed materials are randomly distributed. Furthermore, in the process of drying and removing the dispersant, the binder moves with the dispersant and segregates, while the particulate additives tend to aggregate. Segregation of the binder and agglomeration of the conductive agents may result in poor battery characteristics. To solve these problems, we thought it would be effective to make the base material and the additive material bonded together to form composite particles.

NCM-PEI-GO composite particles were synthesized by forming an ionic complex consisting of polyethyleneimine (PEI) and graphene oxide (GO) on the surface of lithium transition metal oxide (NCM), a cathode active material. In this study, composite particles were synthesized by adding different amounts of PEI and GO, and the effect of the amount of PEI added on the size and thickness of the ionic complexes and the aggregation state of the composite particles was investigated, and the effect of the amount of GO added on the conductivity was discussed. The amount of GO added had no effect on the thickness of the ionic complexes, but had a significant effect on the aggregation of the composite particles.

The conductivity of the NCM-PEI-GO composite particles increased with increasing GO content. This may be due not only to the increase of conductive graphene species in the electrode film, but also to the enhanced conductive path due to the linkage and aggregation of composite particles by ionic complexes.

It is desired for the pharmaceutical intermediate products to form as powder, considering versatility of storage, transportation, and the production schedule adjustment. In this study, aqueous suspension composed of nano- and submicron sized poorly water-soluble drug particles ground by a wet milling was spray dried to produce dry particles. Crystallinity of indomethacin particles was maintained after the spray drying. It was found that mannitol prevented indomethacin particles from cohesion during the spray drying; when indomethacin particles and mannitol in the four times amount of indomethacin were spray dried, mannitol absolutely prevented indomethacin particles from cohesion during the spray drying and the dissolution profiles of the spray dried powder were maintained at the same value as the suspension of indomethacin particles.

The plant-based meat substitutes have been actively developed for the sustainable food production. In this study, we attempted to fabricate the soy protein-based fibers imitating the meat fiber texture by wet spinning technique. The precursor solution containing soy protein isolate and sodium alginate was continuously injected into a calcium chloride solution, resulting in the formation of fibers due to the gelation of alginate cross-linked by calcium ion. The fiber diameter was a few times larger than those of meat muscle fibers and controllable by the speed of rotating collector. The protein content of fiber was close to those of meats, and slightly increased by increasing the soy protein concentration of precursor solution. The mechanical strength of assembled fiber block was almost independent of the soy protein concentration, and was controllable by the sodium alginate concentration of precursor solution. The grilled fiber block had the mechanical strength between those of grilled pork and beef, demonstrating its potential applicability to the meat substitute with simulated nutrition and texture.

In recent years, new thermal insulation materials with lower thermal conductivity and lightweight have been fabricated. However, due to the problems such as heat resistance, their practical use is limited to only below 1000°C. In this paper, the thermal insulation performance of fibrous fumed alumina compacts was evaluated by repeatedly measuring the thermal conductivity at temperatures up to 1200°C. As a result, it revealed that the compacts have low thermal conductivity of 0.040–0.065 W/(m·K) between 200°C and 1000°C. After receiving the heat processing up to 1200°C, its thermal conductivity rapidly increased. However, it was less than half of that of existing ceramic fiber insulation. The compressive strength and flexural strength also increased by the repeated heat processing. The increase of thermal conductivity by the repeated heat processing was explained by the increase of solid thermal flux due to the sintering of particles in the compact and the increase in thermal radiation flux due to the surface oxidation of SiC particles.

The dispersed state of the conductive additives and the binders, which is a fluorine polymer, in the positive electrode material of the lithium ion battery electrode was evaluated by using an energy dispersive X-ray spectrometer attached to scanning electron microscope with a low accelerating voltage. By applying a low accelerating voltage, it is possible to reduce the penetration depth of electron beam into the target material and improve the energy resolution of light elements such as carbon and fluorine. Therefore, it was clarified that the dispersion state of the conductive additives and the binders around one particle of the active material could be observed as element distribution images, and the dispersion state could be quantitatively evaluated as the coverage by image processing. By estimating the coverage of conductive additives and binders on the surface of active materials depending on the dry mixing conditions, it was suggested that this technique could be used for structural design and process optimization of electrodes for improving battery performance.

The platter of hard disk drives contains valuable metals such as the Ruthenium and Platinum. However, these metals were not recycled from the disk for a long time because the low-cost separation and concentration technologies have not been established. In this study, we applied the electrical pulsed discharge method to the separation of the metal layer from the glass substrate in the platter. The relationship between the input voltage and the exfoliating rate by the pulsed discharge was investigated. The discharge plasma was generated between the electrodes placed at the center and the outer boundary of the platter. The metal layer along the path of discharge plasma was separated from the substrate. The exfoliating rate was increased by increasing the charging voltage. The exfoliating mechanism was discussed through by the surface observation and the evaluation of plasma temperature caused by the plasma using an electronic microscope and a spectroscope, respectively.

In this study, a neural network (NN) was applied to a continuous manufacturing process of tablets to predict the tablet physical properties based on a twin-screw granulation operating conditions and tableting pressure. The hyperparameters in the NN model were optimized to accurately predict the tablet physical properties. The constructed NN model successfully demonstrated the predictive capability with the R² of ca. 0.9 in both training and validation. The effects of the granulation operating conditions and the tableting pressure on the tablet physical properties were investigated. It was found that the tableting pressure was the most dominant factor for the tablet hardness and disintegration time. Among the granulation operating conditions, liquid solid ratio had the strongest impact on the tablet physical properties. Focusing on the tableting pressure and liquid solid ratio, the contour maps for the relationships between the operating conditions and the tablet physical properties were obtained by the NN model. It was suggested that the obtained contour maps can be helpful to predict the continuous manufacturing of tablets with the desired tablet physical properties.