Coke Microstructure and Graphitization Across the Hearth Deadman Regions in a Commercial Blast Furnace

Changes in porosity and graphitization degree of coke samples passing through different locations in the hearth deadman of a commercial blast furnace were investigated. SEM-EDS and Raman spectra were used to measure the coke microstructure and carbon structure. It indicates that the final slag migrate into the coke matrix and react with the minerals in the coke, resulting in the various conditions of the compositions of coke minerals. Al2O3 content in the coke matrix is higher compared with the final slag. With the deadman coke downward, the basicity of the slag increases firstly and then decreases. Si particles with diameter of about 30 um are deposited in the coke pores and different shaped Fe3Si are found in the deadman coke. The porosity of coke shows a liner relationship with coke descending. The porosity of coke above the taphole centerline is 27.74%. It is 33.72% near the taphole centerline and is with 42.47% below the taphole centerline. The structure as well as graphitization of deadman coke indicates higher ordering of coke below the taphole centerline regions than that of the other two samples. These results have an important practical significance for the dissolution reaction of coke in the blast furnace hearth.