Simulation of a blast furnace by a mathematical model is one of the means, by which the phenomena in the blast furnace, especially in the high temperature zone, are quantitatively understood. The means described are as follows;taking account of the dead man, the blast furnace from top of bed to tuyere level is devided into five parts, i. e., indirect reduction zone, smelting zone, direct reduction zone, tuyere zone and race-way zone. In each zone the twelve simultaneous ordinary differential equations, consisting of the heat transfer and reaction rate equations, are set up. Rate equations of six kind of chemical reactions and the equations concerning the flow of fluids, which are expected to occur in the blast furnace, have been obtained experimentally. Furthermore, a few parameters are determined, so as the computed curves of pressure drop and temperature to agree with those measured in a actual large blast furnace.
In a actual furnace, it occurs sometimes that the blast pressure increases abnor mally, and then the state of the furnace becomes worse and finally serious. As the results of analysing such case by the use of the mathematical model, the increase of the blast pressure can be predicted before about three hours.