吹込み気泡の溶融金属への吸収速度

Abstract

The absorption of bubbles into a liquid metal was conducted in a 40mm ∅; sinter mullite crucible at 1000°C. Oxygen was blown through the 1.2mm ∅; nozzle of a silica tube into 150-700g silver.The depth of the immersed nozzle H was 9-64mm. The oxygen flow rate Vg was 0.88-3.23 Ncc/sec. The absorption rates of blown oxygen into molten silver were measured by the ZrO2·CaO solid electrolyte galvanic cell. By estimating the diameters and rising velocities of bubbles, the metal phase mass transfer coefficients were obtained. At the smaller depth, the observed values were higher than the theoretical ones by Higbie's model. As the depth became larger, the observed values approached to the theoretical ones. At the lower oxygen concentration, the absorption efficiency of oxygen was very high, but towards the saturated content of oxygen, it dropped rapidly. These phenomena were explained theoretically. In conclusion, the connection with the practical problems was discussed, especially with the oxygen utilization coefficient in open-hearth furnace and converter.