Interfacial phenomenon and Marangoni convection of Fe–C melt on coke substrate under in situ observation

The interfacial phenomenon between liqiuid iron and coke is important for determining the melting efficiency in the blast furnace iron-making process. In this study, the interaction observed in the case of the iron-carbon (Fe–C) melt on coke substrate was investigated using a high-temperature vacuum wettability test equipment. The Fe–C melt did not wet and spread on the coke substrate with different graphitization degrees (r(0)) at a high temperature of 1450 °C. The contact angles changed from 124.5° to 105.3°, and the r(0) increased from 9.30 to 50.00%, thus indicating a nonwetting state. The deepening of graphitization decreased the contact angle. Thereby, increasing the contact area between liquid iron and the carbonaceous material, which facilitated carbon dissolution. The irregular movements of Fe–C melt were observed in situ during the wetting process. The horizontal force of the droplet caused by interfacial tension and the contact angle; the Marangoni convection owing to the gradient of carbon concentration; and the impulse force caused by the generation, aggregation, and release of SiO bubbles at the interface were attributed to the driving force.