Estimation and Verification of Melting Zone Profile in Blast Furnace

Abstract

In order to detect the melting zone profile in a blast furnace, a tracer method has been developed. Including tracers uniformly distributed in a given are layer and analyzing the change of the concentration in tapped metal, the melting process of tracer-containing layer can be estimated. And the profile of melting zone is obtained by transforming the melting ratio of tracer-containing layer to the melting radius at every height in the furnace. The change of the tracer concentration in tapped pig iron is analyzed assuming that the molten metal in the furnace drops smoothly to the hearth and the dilution of the tracer in the hearth acts on a system of first order lag. As the tracer, an Fe-P alloy was used. The melting temperature was obtained as 1350°C by the softening and melting test under load with elevated temperature.
The tracer method was applied to Kakogawa No. 1 blast furnace (3090 m³), whose operating conditions were almost same as those of the shutting down, and the profile of melting zone was estimated. To verify the estimated results, the furnace was quenched with water and the internal state was investigated. The estimated profile of melting zone is in fairly good agreement with the inner profile of softening and melting zone observed after the dissection.