Coke Size Degradation and Its Reactivity Across the Tuyere Regions in a Large-Scale Blast Furnace of Hyundai Steel
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THE blast furnace (BF) is expected to maintain its dominant status in the ironmaking process using iron ore in the future.[1,2] Increasing environmental concerns associated with making coke are influencing the economy of the BF route for steelmaking. To maintain the competitiveness of the blast furnace, the steel industry is looking for opportunities to reduce the reliance on coke consumption in BFs.[3] To reduce the coke consumption rate and increase productivity, supplementary fuels, such as pulverized coal, oil, and gas, are injected through the bottom of the blast furnace. The pulverized coal is considered the most popular supplementary fuel. There have been extensive studies with various aspects of injected fuels, mainly limited to improving the combustion of coal.[4–6] Coke reacts with CO2 during its descent deep inside of the blast furnace and produces CO to be used as the
TAE JUN PARK, KWANG HYUN KO, JONG HYUP LEE, and BYONG CHUL KIM are with the Ironmaking Research Team, R&D Center, Hyundai-Steel Company, 1480 Bukbusaneop-ro, Dangjin-Si, Chungnam, 31719, Republic of Korea. Contact e-mail: [email protected] SUSHIL GUPTA and VEENA SAHAJWALLA are with the School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia. Manuscript submitted November 9, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS B
reducing agent for the reduction of iron ore in the upper part of the blast furnace.[7] This means that high CSR along with low CRI is a prerequisite for coke to withstand the extreme conditions in the blast furnace. This is because the high reaction rate of coke with the oxidizing agent in the blast furnace causes coke to be rapidly weakened and catastrophically degraded into smaller particles, consequently leading to poor permeability, decreasing efficiency of blast furnace performance, and low permeability at the edge of the raceway by coke residue. The current coke quality parameters are measured in simple tests at relatively low temperatures and at atmospheric pressure and as such are constrained by their inability to simulate some of the phenomena of a working BF at extremely high pressure and temperature, such as the graphitization and coke reactions that occur in the very active zone adjacent to the tuyere level. Due to the complexity of reactions in the blast furnace with high temperatures and pressures, it was hard to extract representative coke samples from working furnaces. Recently, however, a tuyere core-drilling technique has enabled operators to effectively extract coke samples from an operating blast furnace, thereby providing a source of potentially useful information about various important phenomena at working conditions.[8–14] In recent years, the number of steel companies operating large-scale blast furnaces has grown to increase production of molten iron. Therefore, there is a need to characterize the behavior of coke fines
generation in different regions of a large BF to understand the degradation behavior of coke in the large-scale blas
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