Abstract:

The physical properties of molten slag in blast furnaces significantly impact the dripping of molten iron and slag, as well as gas permeability, which directly affects the operational efficiency of the entire process. To quantitatively estimate the dripping of molten slag through the coke bed, understanding thermophysical properties—including viscosity and interfacial behavior—is crucial. Furthermore, efforts toward carbon neutrality are expected to cause significant changes in the gas conditions of the blast furnace process. Therefore, this study aims to experimentally clarify the influence of gas composition, particularly H2 addition, on the wettability between molten slag and coke. To achieve this, the wetting behavior between a synthetic CaO-SiO2-Al2O3-MgO-FeO quinary slag and a coke substrate was observed at 1550°C under various gaseous conditions. In addition to the inert gases used in previous studies, a CO-N2 gas mixture was employed to simulate actual blast furnace conditions. Additionally, the partial pressure of H2 was varied from 0 to 0.3 by substituting it for CO. Contrary to previous research conducted under inert gas conditions, the contact angle between the slag and coke did not show any notable change over time, which can be attributed to the presence of CO gas. However, when H2 was added, the wettability of the slag on the coke improved significantly. It was found that dynamic changes in the contact angle were always accompanied by slag penetration into the coke substrate. Detailed interface analysis suggests that this wetting behavior is closely related to the formation of SiC both on the surface and within the substrate. These findings are expected to be valuable for understanding and predicting phenomena in low-CO2 emission blast furnaces.

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Mr. Han Sang Oh