Fumitaka Tsukihashi

Bio: Fumitaka Tsukihashi is an academic researcher from University of Tokyo. The author has contributed to research in topics: Steelmaking & Slag. The author has an hindex of 28, co-authored 195 publications receiving 2805 citations.

Effect of Al2O3 and CaO/SiO2 on the Viscosity of Calcium-Silicate–Based Slags Containing 10 Mass Pct MgO

Abstract: The effect of Al2O3 and CaO/SiO2 on the viscosity of the CaO-SiO2-10 mass pct MgO-Al2O3 slags was studied at fully liquid temperatures of 1773 K (1500 °C) and below. At fixed CaO/SiO2 between 0.8 and 1.3, higher Al2O3 content increased the slag viscosity due to the polymerization of the aluminate structures. At fixed Al2O3 of 15 and 20 mass pct, increasing the CaO/SiO2 from 0.8 to 1.3 resulted in lower viscosity due to the depolymerization of the aluminate structure.

A Kinetic Study of the Effect of Basicity on the Mold Fluxes Crystallization

Abstract: The effect of basicity on the mold fluxes crystallization was investigated in this article. The time-temperature-transformation (TTT) diagrams and continuous-cooling-transformation (CCT) diagrams of mold fluxes with different basicity were constructed by using single, hot thermocouple technology (SHTT). The results showed that with the increase of basicity, the incubation time of isothermal crystallization became shorter, the crystallization temperature was getting higher, and the critical cooling rate of continuous cooling crystallization became faster. The X-ray diffraction analysis suggested that calcium silicate (CaO·SiO2) was precipitated at the upper part of the TTT diagram and cuspidine (Ca4Si2O7F2) was formed at the lower part, when the basicity of mold fluxes was within 1.0 to 1.2. However, when basicity was 0.8, only the cuspidine phase was formed. A kinetic study of isothermal crystallization process indicated that the increase of the basicity tended to enhance the mold flux crystallization, and the crystallization activation energy became smaller. The crystallization mechanism of cupsidine was changing from one-dimensional growth to three-dimensional growth with a constant number of nuclei, when the basicity of mold fluxes varied from 0.8 to 1.2.

Influence of TiO2 on the Viscous Behavior of Calcium Silicate Melts Containing 17 mass% Al2O3 and 10 mass% MgO

Abstract: Iron ores consisting of significant TiO2 such as ilmenite are low cost ores, but due to the high TiO2 content its use may result in significant issues within the blast furnaces such as lower reduction degree,1–4) changes in the liquidus temperature in slag,5–7) lower residual removal by the slag,8–10) and viscosity changes within the bosch and hearth.11–15) However, potential benefits of TiO2 in the blast furnace slags have also been known by forming a protective layer of titanium carbo-nitride on the refractory brick and inhibiting the premature failure and erosion of the hearth.9,15–18) Ohno and Ross13) found TiO2 additions increase the slag viscosity in the CaO–SiO2–Al2O3–TiO2 slags under reducing atmospheres of C/CO equilibrium. Shankar et al.19) revealed the effect of TiO2 in the CaO–SiO2–MgO–Al2O3 slag system, where the viscosity decreased with TiO2 up to 2 mass%. Saito et al.14) found TiO2 lowered the viscosity in the CaO–SiO2–MgO–Al2O3 slag system at 10 mass% and 20 mass% TiO2. However, the viscosity data between 0 to 10 mass% TiO2 is still ill-defined. In this study, the influence of TiO2 from 0 to 10 mass% on the viscous behavior of CaO–SiO2–17 mass%Al2O3–10 mass%MgO slags have been investigated and correlated to the slag structure using XPS (X-Ray Photoelectron Spectroscopy).

Reaction Mechanism between Solid CaO and FeOx–CaO–SiO2–P2O5 Slag at 1 573 K

Abstract: Solid CaO and FeOx–CaO–SiO2–P2O5 slag were reacted for 2 to 2 400 s at 1 573 K. The interface of CaO and slag were observed and analyzed by SEM/EDS. The CaO–FeO layer was formed beside solid CaO. The thickness of the CaO–FeO layer increased with time. Next to the CaO–FeO layer, 2CaO·SiO2 phase was formed in the melt and high content of FeO was included in the liquid. The activities of FeO and CaO for each phase were evaluated and reaction mechanism between solid CaO and FeOx–CaO–SiO2–P2O5 slag was discussed. The activity of FeO for 2CaO·SiO2 saturated melt is larger than that for the CaO–FeO layer, therefore, Fe2+ diffuses from slag phase to solid CaO. Then the CaO–FeO layer is formed beside solid CaO. The pass of the slag composition change accompanied by CaO dissolution are represented in the phase diagram for the FeOx–CaO–(SiO2+P2O5) pseudo ternary system.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Applying cumulative exergy demand (CExD) indicators to the ecoinvent database

Abstract: Goal, Scope and Background Exergy has been put forward as an indicator for the energetic quality of resources. The exergy of a resource accounts for the minimal work necessary to form the resource or for the maximally obtainable amount of work when bringing the resource’s components to their most common state in the natural environment. Exergy measures are traditionally applied to assess energy efficiency, regarding the exergy losses in a process system. However, the measure can be utilised as an indicator of resource quality demand when considering the specific resources that contain the exergy. Such an exergy measure indicates the required resources and assesses the total exergy removal from nature in order to provide a product, process or service. In the current work, the exergy concept is combined with a large number of life cycle inventory datasets available with ecoinvent data v1.2. The goal was, first, to provide an additional impact category indicator to Life-Cycle Assessment practitioners. Second, this work aims at making a large source of exergy scores available to scientific communities that apply exergy as a primary indicator for energy efficiency and resource quality demand.

Outlook of the World Steel Cycle Based on the Stock and Flow Dynamics

Abstract: We present a comprehensive analysis of steel use in the future compiled using dynamic material flow analysis (MFA). A dynamic MFA for 42 countries depicted the global in-use stock and flow up to the end of 2005. On the basis of the transition of steel stock for 2005, the growth of future steel stock was then estimated considering the economic growth for every country. Future steel demand was estimated using dynamic analysis under the new concept of “stocks drive flows”. The significant results follow. World steel stock reached 12.7 billion t in 2005, and has doubled in the last 25 years. The world stock in 2005 mainly consisted of construction (60%) and vehicles (10%). Stock in these end uses will reach 55 billion t in 2050, driven by a 10-fold increase in Asia. Steel demand will reach 1.8 billion t in 2025, then slightly decrease, and rise again by replacement of buildings. The forecast of demand clearly represents the industrial shift; at first the increase is dominated by construction, and then, after ...

Calciothermic reduction of titanium oxide and in-situ electrolysis in molten CaCl2

Abstract: A concept for calciothermic direct reduction of titanium dioxide in molten CaCl2 is proposed and experimentally tested. This production process consists of a single cell, where both the thermochemical reaction of the calciothermic reduction and the electrochemical reaction for recovery of the reducing agent, Ca, coexist in the same molten CaCl2 bath. A few molar percentages of Ca dissolve in the melt, which gives the media a strong reducing power. Using a carbon anode and a Ti basket-type cathode in which anatase-type TiO2 powder was filled, a metallic titanium sponge containing 2000 ppm oxygen was produced after 10.8 ks at 1173 K in the CaCl2 bath. The optimum concentration of CaO in the molten CaCl2 was 0.5 to 1 mol pct, to shorten the operating time and to achieve a lower oxygen content in Ti.