The temperature in the sintering bed is preferably maintained between 1 200°C and 1 400°C during sintering to produce high strength and reducibility sintered ore. To achieve this condition, the technology of combined usage of coke breeze and gaseous fuel, which is fed properly from the top surface of the sintering bed, was developed. In this paper, the effect of oxygen enrichment with combined usage of coke breeze and gaseous fuel on the heat pattern in sintering bed and cold strength of sintered ore was investigated. The cold strength of sintered ore was improved by the oxygen enrichment in the pot test. Then, the holding time over 1 200°C during sintering was extended and improvement of strength would be attributed to promotion of the sintering reaction. By the simulation model calculations based on chemical kinetics, it is considered that the further extension of the holding time over 1 200°C due to oxygen enrichment is caused of an increase in the distance between the combustion points of the coke breeze and gaseous fuel. However, improvement of the cold strength reached saturation over 32 vol.% of the oxygen concentration in suction air. It is also considered that the excessive increase of the distance between the combustion points of coke breeze and gaseous fuel decreases overlap of respective heat transfer and doesn't contribute to the expansion of holding time over 1 200°C.

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