Capillary Infiltration of Slag in Hydrogen-Direct Reduced Iron and Influence on Melting

抄録

The infiltration of slag into the porous structure of Hydrogen Direct Reduced Iron (H-DRI) was studied with computational fluid dynamics to determine the rate of slag infiltration and its effect on heating and melting of H-DRI. It was found that liquid slag rising in an iron walled capillary quickly exchanges its heat and solidifies within 5 capillary radii from the inlet. The resulting effect is that slag infiltration into a porous structure can only occur when the local temperature of the iron matrix is higher than the slag melting temperature of 1523 𝐾.

The convective heating of the porous structure by infiltrating hot slag and the resulting effective thermal diffusivity of the infiltrated structure was used to simulate the heating and melting of 60 and 65% porosity H-DRI for three different infiltration assumptions: no-infiltration, time-dependent infiltration along the slag solidification temperature isotherm, or instant-infiltration. It was found that time-dependent-infiltration and instant slag infiltration results in longer melting time for 60% porosity H-DRI regardless of heat transfer coefficient, and for 65% porosity H-DRI when the heat transfer coefficient is 500 𝑊 𝑚^-2 𝐾^-1. If a significantly higher heat transfer coefficient of 2500 𝑊 𝑚^-2 𝐾^-1 from slag to H-DRI is applied, a slight decrease in melting time was observed for slag infiltrated 65% porosity H-DRI. These results indicate that slag infiltration into H-DRI is not beneficial for melting.