Physical Modeling of Rotary Flux Injection in an Aluminum Melting Furnace

To reduce the environmental impact during purification of molten aluminum, an environmentally friendly flux is being considered as a potential replacement for the highly toxic chlorine-containing gas currently used. However, the reactivity of the flux is much lower relative to the gases, resulting in low-efficiency purification. Here, a new approach using water modeling was implemented to investigate mass transfer between molten aluminum and the flux during rotary flux injection. Silicon oil, air, and water were used as a model flux, gas, and aluminum melt, respectively. The oil and air were injected into the water bath through the shaft of a rotary impeller. Mass transfer between the oil and water was enhanced with increasing impeller rotation rate. The major enhancement mechanism was entrainment and dispersion of oil droplets from the oil layer floating on the water surface. There was a threshold for the impeller rotation rate, which significantly increased the volumetric mass transfer coefficient.