Tetsu-to-Hagane

Steelmaking

Regular Article

Development of Continuous Steelmaking Slag Solidification Process Suitable for Sensible Heat Recovery

Hiroyuki Tobo, Yasutaka Ta, Michihiro Kuwayama, Yuki Hagio, Kazuya Yab ...

2013 Volume 99 Issue 12 Pages 683-692
Published: 2013
Released on J-STAGE: November 30, 2013

DOIhttps://doi.org/10.2355/tetsutohagane.99.683

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The COURSE50 project aims at developing technologies to reduce CO₂ emissions from steel works by approximately 30% in Japan. In order to supply the energy required to separate CO₂, a technology for recovering sensible heat from steelmaking slag is being developed as one theme of COURSE50. A twin roll type continuous slag solidification process to obtain a shape suitable for sensible heat recovery was investigated.
Sheet-like slag was shaped to a thickness of about 7mm in a twin roll pilot-scale experiment. The slag thickness depended on the adhesion of the molten slag rather than the thickness of the solidified slag on the roll. The slag condition suitable for the twin roll method was identified as a liquid phase ratio of 60% or more. Based on a laboratory-scale experiment and heat transfer calculations, a combination process using the twin roll method and a countercurrent flow packed bed is expected to achieve a heat recovery ratio of 30% or more from sheet-like slag.

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Instrumentation, Control and System Engineering

Regular Article

Development of Decision Support System for Operator in Hot Strip Mill

Masanori Kobayashi, Shusuke Yanagi, Yoshio Morimoto, Takashi Ishikawa

2013 Volume 99 Issue 12 Pages 693-699
Published: 2013
Released on J-STAGE: November 30, 2013

DOIhttps://doi.org/10.2355/tetsutohagane.99.693

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It is important to accomplish immediately a proper draft schedule setting method due to coping with the difficulty in rolling strips and the size jump of strips or covering the lack of experience of the younger operator in the hot strip mill. Therefore, a decision support system used when the operator selects the draft schedule has newly developed. This system has an excellent function that helps the operator to take the better each schedule from the past results of the draft schedule and the strip crown ratio schedule.
After applying this system to the actual operation in the hot strip mill, the frequency has been increased in which the operator chooses the draft schedule and the strip crown ratio schedule with the edge wave tendency of the strip shape. In other words, the draft schedule and the strip crown ratio schedule with the center wave tendency of the strip shape gradually faded away. Consequently, the variation of these schedules has been converged into the smaller range than the period before the installation of this system.
This system is now become essential to the operator in the hot strip mill, and contributes the trouble free rolling or the finishing of the strip thickness and crown.

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Surface Treatment and Corrosion

Regular Article

Effect of Preadsorption of Organic Additives on the Appearance and Morphology of Electrogalvanized Steel Sheets

Hiroaki Nakano, Takashi Ura, Satoshi Oue, Shigeo Kobayashi

2013 Volume 99 Issue 12 Pages 700-708
Published: 2013
Released on J-STAGE: November 30, 2013

DOIhttps://doi.org/10.2355/tetsutohagane.99.700

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Zn electrodeposition was performed galvanostatically on a steel sheet at 1500 A/m² in an agitated sulfate solution at 40°C to investigate the effect of preadsorption of organic additives on the lightness and morphology of Zn. The organic additives preadsorbed were classified into two types: 1) polyethylene glycol (PEG), gelatin and stearyl dimethyl benzyl ammonium chloride (SDBAC) (type I), which exhibit the polarization effect on Zn deposition ; 2) saccharin and sodium lauryl sulfate (type II), which exhibit no polarization effect on Zn deposition. The platelet crystals of deposited Zn became small by preadsorption of all kinds of organic additives. The decrease in size of platelet crystals of Zn with the preadsorption is attributed to both the increase in overpotential for Zn deposition and the decrease in epitaxial growth of Zn. The orientation of {0001} Zn basal plane decreased significantly because of an increase in overpotential for Zn deposition by the preadsorption of PEG and gelatin, and the orientation decreased slightly by saccharin and sodium lauryl sulfate in spite of no polarization effect on Zn deposition. The surface roughness of deposited Zn decreased by the preadsorption of organic additives with the exception of SDBAC. This is due to decrease in size of platelet crystals of Zn. The lightness of deposited Zn was increased by the preadsorption of organic additives with the exception of SDBAC. Because Zn deposited ununiformly by the preadsorption of SDBAC, the surface roughness of Zn increased and the lightness decreased.

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Coloration by Zinc-Nickel Composite Electrodeposition from Chloride Solution

Hiroaki Nakano, Syota Kataoka, Satoshi Oue, Shigeo Kobayashi

2013 Volume 99 Issue 12 Pages 709-715
Published: 2013
Released on J-STAGE: November 30, 2013

DOIhttps://doi.org/10.2355/tetsutohagane.99.709

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Zn-Ni composite electrodeposition was performed under coulostatic (515-5145C・m^–2) and galvanostatic (5A・m^–2) conditions on a brass with Ni precoating in an unagitated chloride solution at 23°C to investigate the color and structure of the deposited films. The chromaticity of deposited Zn-Ni composite films changed in a clockwise direction in each quadrant of a*b* diagram of La*b* color space with increasing the amount of charge. The deposited films contained S, Zn and Ni, and the content was in the order of S > Zn > Ni. XPS revealed that the deposited films were composed of ZnS, ZnO and Ni mainly and contained Zn(OH)₂ and Zn slightly. The color of deposited films is attributed to interference of light, and the index of refraction of deposited films composed of ZnS, ZnO and Ni is assumed to be large. When the Ni was excluded from the electrolytic solution, ZnS did not codeposit and the deposition of Zn in metallic state increased. This suggests that the Ni deposition induces the codeposition of ZnS.

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Social and Environmental Engineering

Regular Article

Dynamic Modeling of World Steel Cycle in Buildings

Niina Fujitsuka, Kenichi Nakajima, Yasunari Matsuno

2013 Volume 99 Issue 12 Pages 716-721
Published: 2013
Released on J-STAGE: November 30, 2013

DOIhttps://doi.org/10.2355/tetsutohagane.99.716

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In this work, a dynamic material flow analysis (MFA) was conducted to estimate the global flow and in-use stock of steel for 42countries until 2010. The growth of the future in-use stock and demand for steel for three products (civil engineering, building, and vehicles) towards 2050 was also estimated under the concept of "stocks-driven flows", considering the economic and population growth in every country. Especially, the country differences were considered in estimating the future demand for steel for building.
In addition, we analyzed the steel scrap generation in each product and in every country up to 2050, and investigated the steel use potentials by using waste input-output material flow analysis (WIO-MFA).

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