Erosion Mechanism of Carbon Brick in Hearth of 4000 m3 Industrial Blast Furnace

Abstract

After dissection of a large blast furnace, the erosion mechanism of carbon bricks after service in a blast furnace (BF) hearth was studied. Obvious “elephant foot” erosion characteristics emerged in the height direction of the BF. The existing forms of carbon bricks after service were characterized by X-ray diffraction (XRD), scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS), and chemical analysis. The results showed that Zn and iron erosion above and below the taphole was observed in the BF, while iron and Zn erosion acted only as a key factor of carbon brick erosion. The convective heat transfer coefficient in the lower part of the hearth of the BF was large, which increased the temperature of the hearth sidewall, resulting in the increase in the carbon-unsaturation of the molten iron at the sidewall, and intensified erosion to the hearth sidewall. The average pore size (1.083 μm) of the carbon bricks on the hot-face of the hearth sidewall was smaller than the critical size (2.12 μm) of the molten iron that penetrated the pores of the carbon bricks, which was not conducive to the penetration of molten iron.