CHLORINE FLUXING FOR REMOVAL OF MAGNESIUM FROM MOLTEN ALUMINUM - PARTI, LABORATORY-SCALE MEASUREMENTS OF REACTION-RATES AND BUBBLE BEHAVIOR

Chlorine fluxing is widely used in the aluminum industry for the remov al of magnesium from molten aluminum. Typically, it consists of bubbli ng a nitrogen/chlorine or argon/chlorine mixture into the melt. This P art I of a two-part article describes laboratory-scale experiments on the kinetics of the reactions and emissions during chlorine fluxing fo r magnesium removal. Bubble frequency, size, and residence time were m easured by a two-microphone detection system, which lead to an estimat e of the melt-gas interfacial area. Emissions were found to be low, pr ovided the melt temperature was above the melting point of magnesium c hloride and provided the magnesium content was above a critical level. Experimental results suggested the chlorine supply to be the rate-det ermining factor above this critical level and magnesium mass transport to be the rate-determining factor below the critical level.