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Final report on Contract No. 7210-AA/143, 423, 322, 821; 1 July 1996 to 30 June 2000

Due to increased blast furnace volumes and PCI rates, the remaining coke is exposed to both a longer residence time and an increased metallurgical load. Investigations showed that at high coal injection rates, the degradation of coke can be diminished by increasing the hot strength CSR of the feed coke and, measured mainly at very big blast furnaces, increasing the cold strength I40. This means increasing coke quality requirements with rising hearth diameters. Laboratory measurements on feed and tuyère coke show remarkable differences between the CSR test values and the CSR values of tuyère coke. The stress on coke in the furnace is much higher than the stress simulated in the test. Increasing amounts of mechanically weak graphite diminish the strength of coke. The coke dissolution in iron melts depends on the porosity, reactivity, alkali content and graphitisation of coke. Alkali in coke hampers the dissolution in iron melts by building up a dry, alkali-bearing slag layer. A longer residence time and the alkali attack (simulated in laboratory tests) decrease the CSR values from 55-67% to 5- 20% and correspond with the CSR range, measured at the tuyère coke. The gasification reaction is responsible for the weakening of the coke lumps by increasing porosity, opening new fissures and lengthening existing ones. The effect of gasification is worse at 970°C compared to 1070°C due to the gasification proceeding more deeply into the coke lumps..

Additional information

Authors: HITCHENSEN C, Corus (UK) , Middlesbrough (GB);BENNINGTON C R, Corus (UK) , Middlesbrough (GB);WILMERS R R, Corus (UK) , Middlesbrough (GB);NEGRO P, IRSID, Maizièrez-les-Metz (FR);SERT, IRSID, Maizièrez-les-Metz (FR);STEILER J M, IRSID, Maizièrez-les-Metz (FR);DI SANTE L, CSM, Rome (IT);JANHSEN U, TKS, Duisberg (DE)
Bibliographic Reference: EUR 20105 EN (2002), pp.205. Euro: 14:50
Availability: EUR-OP reference: KI-NA-20105-EN-S. Available from EUR-OP sales agents. URL:
ISBN: ISBN: 92-894-3107-5
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