Evaluation of Aluminum Dross Generation Rate During Mechanical Stirring of Aluminum Through Model Experiment and Numerical Simulation

The present study proposed, for the first time, an evaluation method to predict the generation rate of aluminum dross in melting or holding furnaces during mechanical stirring of molten aluminum through water model experiments and numerical simulation. In the experiments, a gas–liquid interface reaction between CO₂ gas and NaOH solution was exploited as a model reaction between the aluminum melt and air moisture, and perlite particles were used to model dross layer on the free surface of liquid aluminum. The results reveal that the reaction rate is increased with the impeller rotation speed. Besides, the reaction rate depends on the impeller rotation direction, but this dependence is different for the cases of presence and absence of particles on the liquid surface. In the first case, the reaction rate at the counter-clock rotation was higher than that at the clock-wise rotation. On the other hand, in the second case, the clock-wise impeller rotation yielded a higher reaction rate compared to the counter-clock rotation case. These phenomena can be explained by the mass transfer across the gas–liquid interface at the particle-free area.