Iron-Carbon Interface Phenomenon and Reaction Behavior Analysis in Blast Furnace Hearth

The iron-carbon interface plays an important role in hearth, the dissection investigation of BFs was carried out to clarify the iron-carbon interface phenomenon and reaction behavior. The results show that the iron-coke interface can be divided into two types: partial coverage and overall coverage. The molten iron penetration from the interface to the center of coke is found. The hot face of residual carbon brick has obvious embrittlement layers, the pulverization phenomenon of carbon brick is observed, cracks appear in the carbon brick near the iron- carbon brick interface. Many holes in coke are filled with iron and slag, the filling rate increases as the coke moves towards the lower part of hearth. The graphitization degree of coke increases through dissolution precipitation and carbide transformation mechanism, the high graphitization of coke caused by carburization at iron-coke interface is the essential cause of coke deterioration. The flexural strength of carbon brick decreases under the alternate process of penetration and dissolution, effect of Zn. The critical temperature difference for crack generation decreases from 286 degrees C to 208 degrees C after the reaction, which makes it easier for the carbon brick to produce cracks. These cracks produce brittle embrittlement layers, which accelerates the erosion of carbon brick. The carburization of coke and the dissolution carburization of carbon brick are carried out simultaneously in hearth, there is a competitive carburization between iron- coke interface and iron-carbon brick interface. The methods of controlling competitive carburization are put forward to delay the erosion of carbon brick.