Abstract: Aiming to solve the problem of “hot lower part and cool upper part” in blast furnace with oxygen enrichment blowing， this work has developed a model considering necessary conditions in practice to calculate the heat balances of both the high- and low-temperature zones respectively. The model is expected to study the variation of thermal state of blast furnace and the possible corresponding countermeasures in oxygen enrichment blowing operation. This paper describes the process of model development and validation through comparing with practical production data. The result under conditions of the base case shows that， when oxygen enrichment ratio increases by 1%， the top gas temperature decreases by 14℃. For the operation with an oxygen enrichment rate of 1.7%， the heat balances of both high-and low-temperature zones can be ensured with no additional countermeasures. Besides， the difference between the theoretical minimum direct reduction degree calculated by this model and the reduction degree acquired in practice proves that there is still some room to further reduce the fuel rate in blast furnace ironmaking.

Key words: blast furnace, oxygen enrichment, mathematical model, top gas temperature, cohesive zone