Erosion mechanism of harmful elements K and Zn on carbon brick in a 4000 m³ industrial blast furnace hearth

The carbon bricks eroded by harmful elements after dissection investigation in a Chinese 4000m3 blast furnace hearth is studied in detail. The occurrence state of harmful elements is characterized by chemical analysis, X-ray diffraction and scanning electron microscopy-energy dispersive spectroscopy. The results show that the content of K and Zn in the carbon brick at the tuyere of blast furnace is the highest. ZnO is the main reason for the formation of macro cracks and brittle layer of carbon brick., and K2O and KCl generated by liquid K and blast furnace gas may be the inducements for the formation of brittle layers. The nucleation and growth of ZnO in carbon bricks will undergo three processes: the heterogeneous nucleation of ZnO cell on the surface of C, the heterogeneous nucleation of ZnO cell on the surface of ZnO, and the continuous collision and growth of ZnO cell.