| 1. |
Tatsuya Kon, Hiroyuki Hosokawa, Nobuyoshi Imaoka, Kimihiro Ozaki, Coercivity of Fe-Mn powders prepared through hydrogen reduction of wet-process-synthesized oxide powders, JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 10.1016/j.jmmm.2022.169110, 551, 2022.06, In this study, metallic Fe-Mn soft magnetic powders were produced via hydrogen reduction of the oxide powders consisting of nanoferrites produced by a wet process. The effects of solution concentration and pH value during the wet process on the magnetization and coercivity after the hydrogen reduction were investigated. The experimental results indicated that the solution concentration exhibited no effect on the coercivity, whereas the pH produced a large effect on the coercivity. In the wet process at pH greater than 12, irregular-shaped oxide powders were precipitated. The reduced irregular-shaped metallic Fe-Mn powders showed a small coercivity of approximately 90 A/m. In contrast, at pH = 7-8, both irregular-and plate-shaped oxide powders were precipitated, and the reduced Fe-Mn powders showed a large coercivity of ~& nbsp; 250 A/m. The reduced plate-shaped Fe-Mn powders exhibited smaller grain sizes (diameter: 15.9 mu m) than those of the irregular-shaped Fe-Mn powders (diameter:-~& nbsp; 120-140 mu m), indicating that the plate-shaped Fe-Mn powders exhibited increased coercivities. The plate-shaped metallic powders were produced by the reduction of the plate-shaped oxide powders, which contained ferrihydrite and green rust. These results reveal that the pH value of the wet process changes the oxide shape, which in turn affects the shape and grain size of the metallic Fe-Mn powders. By optimizing the wet process conditions, the coercivity of the Fe-Mn powder was improved to 80.9 A/m, although this value is lower than that of the atomized pure Fe powders.. |
| 2. |
Shungo Natsui, Shingo Ishihara, Tatsuya Kon, Ko-ichiro Ohno, Hiroshi Nogami, Detailed modelling of packed-bed gas clogging due to thermal-softening of iron ore by Eulerian-Lagrangian approach, CHEMICAL ENGINEERING JOURNAL, 10.1016/j.cej.2019.123643, 392, in press, 2020.07, Eulerian-Lagrangian numerical scheme is applied for analysing packed-bed-structure constructions involving non-spherical solids, such as metallurgical cokes and ferrous ores, and the high-temperature softening characteristics of such beds. 3D scanning is applied for determining the coke and ore shapes, and a multi-sphere discrete element method is used as the functional scheme for non-spherical solid-particle motion tracking. The transient deformation behaviour of the softening ore is simulated using the advanced discrete element method, and the gas permeability characteristics exhibited by the ore shapes in the ironmaking process are discussed. Based on this model, cases with varied softening behaviour represented by the joint spring coefficient are investigated and the effect of the ore-softening behaviour on the gas permeability is evaluated. It is established that the pathway of the passing rivulet depends upon the softening-ore deformation behaviour.. |
| 3. |
Kon, Tatsuya, Natsui, Shungo, Ueda, Shigeru, Inoue, Ryo, Ariyama, Tatsuro, Influence of Physical Properties of Melt on Liquid Dripping in Packed Bed Analyzed by MPS Method, ISIJ INTERNATIONAL, 10.2355/isijinternational.53.590, 53, 4, 590-597, 2013.03, The liquid dripping under the cohesive zone influences gas flow and permeability in the lower part of the blast furnace, and it is closely related to blast furnace productivity and operational stability. Especially, liquid distribution and hold-up in the coke packed bed can be mentioned as important phenomena regarding the liquid dripping. Although these phenomena are influenced by the structure of the packed bed and the physical properties of the melt, numerical analysis of blast furnace based on melt properties is difficult. Therefore, in this research, the influence of the physical properties of the melt on liquid flow distribution and hold-up phenomena was studied by modeling the liquid flow in a packed bed and performing numerical analysis based on Moving Particle Semi-implicit (MPS) method, which is one of the particle methods. The results of the analysis clarified the fact that the viscosity of the liquid is the controlling factor for dynamic hold-up, and solid-liquid wettability is the controlling factor for static hold-up.. |
