Kinetic studies have been made on SiO2 inclusion removal from molten Cu to Li2O-SiO2-Al2O3 slag under Ar gas injection stirring condition. The effect of gas injection on the inclusion removal rate has been investigated. Experiments were done at 1523K. The gas flow rate of injected Ar was in the range of 360cm3/s under the conditions of 1523K and 1.013 × 105Pa. The crucible diameters were 30, 40, 60, and 75mm. During each experimental run, the frequency of bubble formation was measured by means of a pressure pulse technique.
The bubble size ranged from 7 to 18mm. From the [mass%O]T-time relation, the rate constant of inclusion removal ko, was obtained. It is shown that koincreases with increasing Ar gas flow rate, Vg. The rate of inclusion remove increases with increasing gas-metal interfacial area. A mathematical model is developed to explain the experimental result. In the model, the inclusion particles are assumed to adhere to the gas bubble-metal interface during the bubble formation and ascent periods. The apparent mass transfer coefficient, km, for inclusion removal obtained experimentally is independent of the gas flow rate and the crucible diameter. Thus, it is considered that the inclusion particles are removed from the melt mainly through adhesion to the gas bubble-metal interface.
