Agenda for low reducing agent operation of blast furnace: Thermophysical properties of molten slags on the gas permeability at the dripping zone of blast furnace

Currently, low reducing agent operation of blast furnace is actively investigated in order to reduce CO2 emission. However, low reducing agent operation accelerates coke wear, resulting in the decrease in the void fraction in the blast furnace. Particularly, at the dripping zone, the decrement in the void fraction increases the hold-up amount of liquid burden. As a consequence, the gas permeability at the dripping zone becomes lower dramatically. In the present paper, we have focused on the effect of thermophysical properties of molten slags on the gas pressure drop and the liquid hold-up, the measures of the gas permeability, in the counter-current region of gas-liquid flow. It has been considered from the results of hold-up experiments and/or simulations that the surface tensions of molten slags and their contact angles against carbonaceous materials are the most significant properties for the gas pressure drop as well as the liquid hold-up. The previous studies with respect to their properties have been reviewed for the slag compositions and the temperatures close to those at the dripping zone.