Chlorine fluxing for removal of magnesium from molten aluminum part I. Laboratory-scale measurements of reaction rates and bubble behavior

Abstract

Chlorine fluxing is widely used in the aluminum industry for the removal of magnesium from molten aluminum. Typically, it consists of bubbling a nitrogen/chlorine or argon/chlorine mixture into the melt. This Part I of a two-part article describes laboratory-scale experiments on the kinetics of the reactions and emissions during chlorine fluxing for magnesium removal. Bubble frequency, size, and residence time were measured by a two-microphone detection system, which lead to an estimate of the melt-gas interfacial area. Emissions were found to be low, provided the melt temperature was above the melting point of magnesium chloride and provided the magnesium content was above a critical level. Experimental results suggested the chlorine supply to be the rate-determining factor above this critical level and magnesium mass transport to be the rate-determining factor below the critical level.