Influence of Mineralogical Characteristic of Hematite in Self-fluxed Sinter on Its Degradation during the Reduction

Inazumi, Tadahiro; Shinada, Koichi; Kawabe, Masayuki

doi:10.2355/tetsutohagane1955.68.15_2207

Cited by 27 publications

(26 citation statements)

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“…Similarly, Inazumi et al reported that the reduction of sinter particles from hematite to magnetite by CO tended to proceed on the surface and the stress generated by the volumetric expansion of iron oxide causes crack formation. 18) However, in the case of H 2 reduction, Asada 10) indicated that no cracks were formed in the magnetite phase, even the phase transformation from hematite to magnetite completed, but many cracks were found in the multi-component calcium ferrite and volumetric expansion of magnetite phase was also observed. It had been reported that there was no obvious difference in the chemical reaction rate of the reduction from hematite to magnetite in a single particle ore between CO/CO 2 and H 2 /H 2 O atmosphere, 19) but the interdiffusion coefficient De of H 2 /H 2 O gas was much higher than that of CO/CO 2 .…”

Section: Comparison Of Co and H 2 Reduction Behaviorsmentioning

confidence: 99%

Reduction Disintegration Behavior of Lump Ore in COREX Shaft Furnace

Liu

2015

ISIJ International

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The heavy disintegration of lump ores would produce plenty of small particles in COREX shaft furnace, which would decrease the gas permeability and productivity of the shaft furnace, thus the proportion of lump ores in the burden of COREX shaft furnace is limited to a low level. In this work, the reduction disintegration behavior of lump ore samples was studied by simulating the reduction process of COREX shaft furnace. The influence of temperature, reduction time and gas composition on the reduction disintegration index (RDI -6.3 ) of lump ore samples were also evaluated. The results showed that the disintegration behavior of lump ores in COREX shaft furnace could be generally divided into three steps and the disintegration mainly occurred in the second step, which was in the temperature zone from 450°C to 650°C with low reduction degree. Meanwhile, the RDI -6.3 of lump ore samples all presented the tendency of "inverted V-shape" in the temperature range from 450°C to 650°C under different reduction time. However, the mutual promotion of reduction reaction and carbon deposition reaction (CDR) was attributed to the main reason for the heavy disintegration of lump ores in COREX shaft furnace. In addition, increasing H 2 concentration in reducing gas and rapid reducing at higher temperature would decrease the disintegration degree of lump ores in COREX shaft furnace.

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Section: Comparison Of Co and H 2 Reduction Behaviorsmentioning

confidence: 99%

Reduction Disintegration Behavior of Lump Ore in COREX Shaft Furnace

Liu

2015

ISIJ International

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“…[121][122][123] Starting with Fuji Iron & Steel Hirohata Works, all companies initiated sinter reduction degradation testing, 121,124,125) and in 1974, the 44th Ironmaking Committee of the Iron and Steel Institute of Japan established a RDI standard procedure as an index for sinter reduction degradation. Countermeasures for improving RDI have been developed, including increases in sinter basicity (CaO/SiO2), 121) gangue amount, 121,126) and FeO content (manufacture of magnetite sinter) 121,127) and addition of chlorides. 128) In 1977, the Technical Research Institute at Nippon Steel Muroran Works began measurement of high temperature characteristics using testing equipment capable of continuous measurement from softening to molten dripping.…”

Section: Improvement Of Sinter Qualitymentioning

confidence: 99%

Ironmaking Technology for the Last 100 Years: Deployment to Advanced Technologies from Introduction of Technological Know-how, and Evolution to Next-generation Process

Naito

Takeda²,

Matsui³

2015

ISIJ International

106

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The 150 year history of the Japanese steel industry dates from the first western blast furnace, which was built by T. Ohashi in 1857. Modern blast furnace operation at integrated steel works in Japan started in 1901 with the first blow-in of Higashida No. 1 blast furnace at Yawata Steel Works. Throughout the prewar and postwar periods, the steel industry has supported the Japanese economy as a key industry which supplies basic materials for social infrastructure and development.After the period of recovery following the destruction caused by World War II, Chiba Works of Kawasaki Steel Corporation (now JFE Steel Corporation) was built and began operation in 1953 as the first integrated steel works in the Keiyo Industrial Region after the war. During Japan's period of high economic growth, many coastal steel works with large blast furnaces having inner volumes of more than 3 000 m 3 and even 5 000 m 3 were built to enable efficient marine transportation of raw materials and steel products. Japanese steel makers introduced and improved the most advanced technologies of the day, which included high pressure equipment, stave cooler systems, bell-less charging systems, etc. As a result, Japanese steel works now lead the world in low reducing agent rate (RAR) operation, energy saving, and long service life of blast furnaces and coke ovens.Following the Oil Crises of the 1970s, the Japanese steel industry changed energy sources from oil to coal and implemented cost-oriented operation design and technology. In 2012, the Japanese steel industry produced approximately 80 million tons of hot metal from 27 blast furnaces, including large-scale furnaces with inner volumes over 5 000 m 3 . During this period, the industry has faced many economic and social challenges, such as the high exchange rate of the yen, oligopoly in the mining industry, global warming, and the surge in iron ore and coal prices driven by the rapid growth of the BRICs. The industry has successfully responded to these challenges and maintained its international competitiveness by developing advanced technologies for pulverized coal injection, expanded use of low cost iron resources, recycling for environmental preservation, and CO2 mitigation.In this paper, the prospects for ironmaking technologies in the coming decades are described by reviewing published papers and looking back on the history of developments in ironmaking during the last 100 years.

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“…It was reported that skeletal rhombohedral hematite in sinter resulted in significant size degradation due to its mineralogical characteristics, i.e., a skeletal form having inclusions, parallel intergrowth and being locally generated near open pores. 14,15) Crack propagation in sintered matrix is a dominant factor as well. 16,17) At present, however, the influence of the pore structure on cold strength and low-temperature reduction disintegration is still unknown.…”

Section: Introductionmentioning

confidence: 99%

Influence of Artificially Induced Porosity on Strength and Reduction Behavior of Hematite Compacts

Higuchi

Heerema

2005

ISIJ Int.

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With the objective to gain more fundamental understanding of the influence of pore structure on the lowtemperature reduction behavior of iron ore agglomerates, laboratory-scale induration experiments were performed using pure hematite compacts doped with naphthalene as a porosity-generating agent. The pore structure was thus controlled up to 60 % porosity and 1.4 mm pore diameter, and no mineralogical changes were observed in these ranges after induration. The cold strength of indurated compacts was higher with pores smaller than 0.125 mm in diameter, as well as with pores larger than 1 mm. Changes in the cold crushing behavior of indurated compacts are discussed based on matrix length and distribution theory. Reduction tests in CO-CO 2 -N 2 gas at temperatures in the range of 350-800°C revealed high strength after reduction of compacts with fine pores less than 0.125 mm in diameter. Reasons for this high strength were the isotropic stress distribution within the compacts, as well as lower expansion due to development of a complex reduction front.

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Influence of Mineralogical Characteristic of Hematite in Self-fluxed Sinter on Its Degradation during the Reduction

Cited by 27 publications

References 0 publications

Reduction Disintegration Behavior of Lump Ore in COREX Shaft Furnace

Reduction Disintegration Behavior of Lump Ore in COREX Shaft Furnace

Ironmaking Technology for the Last 100 Years: Deployment to Advanced Technologies from Introduction of Technological Know-how, and Evolution to Next-generation Process

Influence of Artificially Induced Porosity on Strength and Reduction Behavior of Hematite Compacts

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