Microstructure analysis and mineral phase transformation of coke in blast furnace

In order to reveal the actual reaction behaviour and degradation mechanism of coke, chemical composition, mineral phase transformation and microstructure of coke at different locations in blast furnace were characterized. Meanwhile, the wear and compressive resistance, as well as the secondary thermal characteristic, were carried out. Results indicated that the mineral species and contents of cokes were significantly affected by alkali metal minerals adhesion and molten slag-iron corrosion. The alkali minerals and iron minerals adsorbed on the pore walls contributed to catalytic degradation of the bosh coke and tuyere coke respectively. In the upper zone of BF, the wear and compressive resistance of coke first decreased and then increased. The secondary thermal performance of BF coke was inverse with the content of alkali metal. The macropore structure of the hearth coke with the maximum graphitization disappeared to be replaced by slag and iron.