Measurement of Bubble Size Distribution and Generation Position of Bubbles Generated during Smelting Reduction of Iron Oxide-containing Slag

Slag foaming is a phenomenon caused by the generation of CO bubbles due to the reaction between iron oxide in slag and carbon in pig iron. The purpose of this study is to explore the controlling factors of slag foaming by observing the bubble formation behavior caused by the chemical reaction between iron oxide and Fe–C alloy in slag. 0.06 g of Fe–C alloy was charged to the bottom of the BN crucible, and 6.0 g of slag (SiO₂:CaO:Fe₂O₃ = 40:40:30) was charged on top of it. The crucible was placed in an infrared image heating furnace, and the temperature was rapidly raised to 1 370°C at a rate of 1 000°C/min in a N₂ stream, then held for a predetermined time and rapidly cooled. After rapidly cooling, the internal structure of the sample was observed using a high-resolution X-ray CT device. The spherical equivalent volume is calculated based on the number of bubbles observed and their equivalent circle diameter, and the relationship between the volume ratio of small bubbles in the slag volume and the distance from the bottom of the crucible is calculated, and the bubble density and volume ratio are calculated. It was suggested that the value tends to increase as the distance from the bottom of the crucible increases.