In-Kook SUH - Academia.edu (original) (raw)

Papers by In-Kook SUH

Metals and Materials International, Nov 1, 2023

ISIJ International

Silico-ferrite of calcium and aluminum (SFCA) is the primary bonding phase of iron ore sinter, th... more Silico-ferrite of calcium and aluminum (SFCA) is the primary bonding phase of iron ore sinter, the world's most popular artificial feed material for ironmaking. However, fundamental questions about its crystal structure and the atomic occupancy at each site remain unanswered. To date, the quantitative phase analysis (QPA) of SFCA has mostly been conducted using two-dimensional information and only provided information regarding phase fractions. In contrast, Rietveld analysis uses bulk data and provides lattice information in addition to phase fraction information. This study investigates the effects of basicity and Al 2 O 3 concentration on the crystal structure and atomic site occupancy of SFCA through Rietveld analysis of the X-ray diffraction patterns. Raman spectroscopy and micro-Vickers hardness tests are used to verify the analytical results. Changes in the chemical composition affect the atomic occupancies at sites Si1 (Si-Al), Ca2 (Ca-Fe), Ca3 (Ca-Fe), Fe4 (Fe-Al), Fe5 (Fe-Al), and Fe7 (Fe-Al). With increasing basicity or Al 2 O 3 content, the microhardness increases linearly, which can be attributed to the modification of atomic site occupancies. The crystalline structure obtained in this study is essential for developing a thermodynamic model of SFCA that can be used to predict its phase stability. This information can then be used to design a novel high-performance iron ore sinter.

Minerals, 2021

The sintering process is a thermal agglomeration process, and it is accompanied by chemical react... more The sintering process is a thermal agglomeration process, and it is accompanied by chemical reactions. In this process, a mixture of iron ore fines, flux, and coal particles is heated to about 1300 °C–1480 °C in a sinter bed. The strength and reducibility properties of iron ore sinter are obtained by liquid phase sintering. The silico-ferrite of calcium and aluminum (SFCA) is the main bonding phase found in modern iron ore sinters. Since the physicochemical and crystallographic properties of the SFCA are affected by the chemical composition and mineral phases of iron ores, a crystallographic understanding of iron ores and sintered ore is important to enhance the quality of iron ore sinter. Scrap and by-products from steel mills are expected to be used in the iron ore sintering process as recyclable resources, and in such a case, the crystallographic properties of iron ore sinter will be affected using these materials. The objective of this paper is to present a short review on resea...

Metallurgical and Materials Transactions B, 2020

The effects of basicity and Al2O3 content on the chemistry of phases in iron ore sinter containin... more The effects of basicity and Al2O3 content on the chemistry of phases in iron ore sinter containing ZnO were investigated by Rietveld analysis of the X-ray diffraction (XRD) patterns. Bulk composition analysis was carried out using inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and wet-chemical analysis. The composition of each phase was investigated using a scanning electron microscope-energy dispersive X-ray analyzer (SEM-EDX). It was found that ZnO exists in the franklinite and the silicoferrite of calcium and aluminum (SFCA) phases. With increasing ZnO content, the phase fraction of the franklinite increased, while the fraction of SFCA slightly increased. When ZnO content was fixed at 1 wt pct and basicity increased, the fraction of franklinite decreased and that of SFCA increased. Here, the solubility of ZnO in the SFCA increased. As the Al2O3 content increased, the fraction of franklinite decreased and that of SFCA increased, while ZnO content in the SFCA did...

$Research paper thumbnail of Structural Study of the Molten CaO-Fe2O3 System by X-ray Diffraction$

Zeitschrift für Naturforschung A, 1989

The structure of molten CaO - Fe2O3, with CaO content from 33 to 60 mol% was studied by means of ... more The structure of molten CaO - Fe2O3, with CaO content from 33 to 60 mol% was studied by means of high temperature x-ray diffraction. At higher CaO concentrations the iron atoms were found to become more and more tetrahedrally by rather than octahedrally surrounded by oxygens. The present structural information is consistent with the reported results on the viscosity of this system.

$Research paper thumbnail of Structural Study of Binary Phosphate Glasses by X-ray and Neutron Diffraction$

ISIJ International, 2014

This study aims to utilize the high Al2O3 pisolitic ore in sintering process by designing the qua... more This study aims to utilize the high Al2O3 pisolitic ore in sintering process by designing the quasi-particle where the pisolitic ore is used as nuclei and ultra-fine hematite and magnetite ores are employed as adhering fines. The assimilation behavior between nuclei and adhering fines was investigated through microstructure analysis and it was correlated to sinter quality. When ultra-fine hematite ore was used as adhering fines, the low viscous melt of CaO•Fe2O3 was formed in the assimilation. Since this results in the low extent of Al2O3 localization and the porous structure, the detrimental effect of Al2O3 on the strength was not fully controlled. On the other hand, for the ultra-fine magnetite ore, 3CaO•Fe2O3•3SiO2 melt with high viscosity was predominantly participated in the assimilation. The assimilation was suppressed by the formation of 'interfacial layer'. Due to the dense structure and high extent of Al2O3 localization, the detrimental effect of Al2O3 on strength was reasonably controlled. The quasi-particle comprising high Al2O3 pisolitic ore and ultra-fine magnetite ore showed the equivalent sinter quality to the quasi-particle sample consisting of nuclei of dense hematite and adhering fines of ultra-fine hematite resulting in the high sinter quality.

Journal of the Ceramic Society of Japan, 1990

$Research paper thumbnail of High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction$

Journal of Materials Science, 1988

The thermal expansion of silver, gold, copper, nickel, molybdenum and tungsten has been measured ... more The thermal expansion of silver, gold, copper, nickel, molybdenum and tungsten has been measured by the dilatation method. The thermal expansion values of silver, gold, copper and nickel have also been evaluated from lattice parameter measurements by X-ray diffraction. These six metals were found to exhibit a nearly uniform expansion over the temperature ranges covered. The thermal expansion values obtained by the dilatation method are in good agreement with those determined by X-ray diffraction. The present results appear also to agree well with those reported previously in the literature.

ISIJ International, 2012

CaO-(0-20 mass%) and SiO2-containing (0-30 mass%) wüstite ('FeO') compacts were isothermally redu... more CaO-(0-20 mass%) and SiO2-containing (0-30 mass%) wüstite ('FeO') compacts were isothermally reduced at 1 273 K under CO and H2 gas. Prior to reduction, the phase of dicalcium ferrite (Ca2Fe2O5) and fayalite (Fe2SiO4) was equilibrated with 'FeO' at 1 273 K under 50%CO/50%CO2 and identified using X-ray diffraction and scanning electron microscopy. The rate of reduction for CaO-containing 'FeO' compacts under both H2 and CO increased up to the vicinity of 2.5 mass% CaO, and then decreased with higher CaO dependent on the formation of an intermediate phase of dicalcium ferrite. For SiO2-containing 'FeO', the rate decreased with SiO2 additions. When the dense fayalite is present reduction using CO was limited, while considerable reduction was observed using H2. The reduction was affected by three distinct reduction mechanisms of interfacial chemical reaction, gaseous mass transport, solid state diffusion of oxygen or a combination of these individual mechanisms termed the mixed control. The contribution of each mechanism with the content of CaO or SiO2 affecting the reduction behavior was determined. The compact porosity increased when CaO was added to approximately 2.5 mass% and subsequently decreased with higher CaO, but continuously decreased with SiO2 additions. The ratio of the effective diffusivity (De) to molecular interdiffusivity (D) was highest at the vicinity of 2.5 mass% CaO and thus the maximum reduction rate was obtained when the porosity was highest.

High Temperature Materials and Processes, 1988

The main function of non-ferrous metallurgical slags is collecting oxidized iron. For this reason... more The main function of non-ferrous metallurgical slags is collecting oxidized iron. For this reason these slags, unlike ferrous metallurgical slags, are highly acid. The major industrial problems associated with iron-silicate slags presently employed in non-ferrous metallurgical operation are metal losses in the slag phase, magnetite precipitation, and rather high viscosity. A review of our knowledge on these aspects is surveyed in this article. The atomic scale structure determined by x-ray diffraction is also presented, in order to facilitate fuller understanding of various properties of slag melts. Various thermodynamic data of ferrite-base and soda-base slags obtained recently suggest wide applicability in various non-ferrous metallurgical processes. For this reason, an attempt has been made to review the presently available information about these relatively new type slags including their process implications.

High Temperature Materials and Processes, 1989