Measurement of concentration of boron in stainless steel-boron carbide (SS-B₄C) alloy is in high demand for the decommissioning of the damaged nuclear reactor. In this study, quantitative determination of boron concentration in SS-B₄C alloy containing about 0.5 to 4mass% of boron was investigated by using inductively coupled plasma optical emission spectrometry (ICP-OES). The samples were dissolved completely with the combination of phosphoric-and-sulfuric-acids method and alkali-fusion method. Analytical line of 182.52 nm in wavelength was used to detect boron. The limit of quantification of boron in this method was 0.3 μg mL^-1. The analytical results were in good agreement with nominal values in high concentration sample. Boron in the sample having the concentration as low as 0.5-1 mass% can be successfully detected.

　　　The dissolution rate of oxygen into a molten metal bath is responsible for the efficiency of decarburization in the steelmaking industry. Oxygen is commonly introduced into the bath using many kinds of injection devices. The dynamic behavior of oxygen bubbles thus generated in the bath mainly governs the oxygen dissolution rate. Model experiments were carried out in this study to understand the oxygen bubble behavior. Water and air were chosen for the models of molten metal and oxygen, respectively. Air was injected horizontally into a cylindrical water bath through an immersed L-shaped lance. The dispersion patterns of bubbles and related bath surface oscillations were observed with a high-speed video camera and a still camera. The patterns were classified into seven types under the experimental conditions considered in this study.

　　　In order to utilize iron scraps as iron resource, removal of impurity elements is necessary. In current refining process, impurities are removed to molten slag by oxidation from molten iron. However, some elements, such as Cu, are difficult to be removed from molten iron by current ways due to their chemical stability. Therefore, new refining technique is required. Since Ag is nobler than Cu, oxidation removal of Cu from molten iron can be possible via Ag phase. In order to confirm the condition of multiple phase to coexist, experiments were carried out with Fe-2mass%Cu-6mass%C alloy under distributed temperature to study a principle of steel-refining through multiple phases. Dendrites of γFe(s) and C(s) precipitated in upper part of a sample at low temperature. γFe(s) with C(s) inside was stabilized in upper part of a sample against high density of Fe. Then, it was possible to keep the multiple phases of γFe(s), Fe-C(l) and Ag(l). A distribution of Cu concentration under distributed temperature was observed.

　　　In steelmaking process, oxygen gas supplied into molten iron could induce spitting phenomena which raise problems such as low yield ratio and deposition inside the vessel. However, the effect of operating condition on spitting is not clarified. In the present paper, channel-type recirculating water bath and top blowing of compressed air are used to clarify the effect of cavity shape on spitting rate. Primary cavity size including depth and width changes periodically. and secondary cavity is observed inside the primary cavity. The formation rate of secondary cavity decreases at upstream side and increases at downstream side with the increase of recirculating rate. Time-average cavity shape could not explain the spitting rate. However, the formation rate of secondary cavity correlates well with spitting rate.

　　　The rise in electric vehicle etc. have led the increase in productions of lithium ion batteries (LIBs), and will do in the future. Thus, the recovering technology of lithium from used LIBs is essential for the stable supply of lithium because of uneven distribution of lithium resources and producers. In this study, a method for extracting lithium from Ni-Co-Mn ternary cathode material in LIBs through the vaporization of lithium carbonate was proposed based on simple thermodynamic calculation. We investigated the behavior of Li in simulated cathode material under CO₂-CO atmosphere at 1673 K, which is above the boiling point of Li₂CO₃. In addition, the selective recovery of lithium from simulated cathode material was demonstrated. We found out that Li is selectively separated from simulated cathode material and Li₂CO₃ is directly obtained by our proposed method.

　　　Due to the massive amount of CO₂ emission, it is required to reduce CO₂ emission from blast furnaces. High reducibility of iron oxide on the initial melt formation stage is necessary to reduce CO₂ emission. In order to estimate the effect of melt on reduction behavior and rate of sintered iron oxide pellet, heating-up reduction from 1000℃ to 1200℃ and isothermal reduction at 1200℃ were carried out. Samples were composed of Fe₂O₃, CaO, SiO₂ and Al₂O₃. Three kinds of samples of different (mass%CaO)/(mass%SiO₂) (C/S) were prepared in order to observe the effect of composition on the reduction rate. Reduction rate of samples were lowered over the initial melt formation temperature calculated by FactSage. Effect of melt formation on microstructure inside sample was observed by SEM and porosities were estimated by image analysis technique. Amount of melt increased and reduction rate decreased with increasing C/S. Pore occlusion ratio which was defined here increased with decreasing C/S and overall reduction rate decreased linearly with increasing pore occlusion ratio.

　　　In this paper, we propose a novel evaluation method for forensic science, which uses FEM analysis and a drop-weight test, in order to evaluate the human body damage by blunt weapons. In judging child abuse and confirming the authenticity of its guilt, knowledge by scientific investigation is required for objective and quantitative evaluation in Japan. However, it is considered to be a problem that highly accurate investigations, which considers the differences among individuals, have not been performed and the evaluation based on easy-to-understand criteria have not been established for the Japanese lay judge system. Therefore, in this study, we designed new experiments: one was fracture load measurement of newborn porcine tails with a force tester and the other was FEM analysis of the fracture load which simulated the real experiments. As the results of both experiments, we estimated the fracture load of an infant's skull with high accuracy. We investigated the fracture behavior in the FEM analysis with a load area of 100-1000 mm2 and concluded that the obtained fracture load corresponds to fall height of more than 1.2 m by comparing with the load which was obtained by dropping a weight of 30% of the infant weight.

　　　Shot blast devices and shot peening devices are used in surface processing in steel manufacturing. Shot process is used to give micro-distortions to the product surface in order to strengthen surface toughness. However, micro-distortions often produce changes in the magnetic properties of steel objects. Residual magnetization also remains in objects after handling by magnetic lifters. This residual magnetization is not particularly strong but is sufficient to attract shot particles, and some of the attracted particles remain on the object surface. Remaining particles become the obstacles in following processes such as a painting line. To avoid remaining shot particles, the authors developed a shot particle removal device using permanent magnets and carried out magnetic field simulations to optimize the design of this device. Some of the simulations described in this paper show conditions which include the strength and duration of magnetization for particle removal. Other simulations show the optimal position of the permanent magnets and adjustment steel plates to satisfy those conditions. The simulation results show that some shot particles are adsorbed by residual magnetization and remain on the object surface. The authors confirmed effectiveness of the removal device by some experiments.