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 slagiron 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.

In order to explore the erosion reason of the hearth sidewall built with high thermal conductivity and small hot-pressed graphite carbon bricks, the carbon brick samples were obtained by boring in different parts of the hearth sidewall. By the research on microcosmic structure, thermal conductivity, chemical composition of the carbon bricks, it was concluded that the high portion of large size pore leaded to poor properties of resistance to Zn permeation. And due to the formation of the weakened layer, the transfer system of lining was destroyed, which result in poor effect of titanium protecting and resistance to hot metal erosion. For the purpose of prolonging the campaign of BF hearth, the properties of resistance to hot metal erosion and the thermal conductivity of carbon brick should be matched well.