Magnesium removal from molten aluminum by Cl2 bubbling

Abstract

The experiments were performed by introducing Cl2 gas bubbles into Al melt in order to obtain basic information on the removal of Mg component. Thermodynamic calculations were performed to confirm the feasibility of Mg removal from Al melt. A mixture of Ar and Cl2 gas with a mixing ratio of 10–50% in a total flowrate of 50–100 sccm was bubbled into Al melt at 1000–1100 K. Mg could be removed from Al melt by Cl2 gas bubbling and the rate of removal depended largely on the total gas flowrate and the Cl2 mixing ratio. A greater rate of decreasing Mg was observed with a higher Cl2 mixing ratio in the bubbling gas. It was estimated that the removal rate of Mg complied with zero order kinetics. The rate-controlling step was estimated to be the mass transfer in Al melt. The activation energy for Mg removal by Cl2 gas bubbling was determined to be 63.1 kJ/mol. The mechanism of Mg removal from Al melt by Cl2 gas bubbling was proposed. The aluminum chlorides were formed by Cl2 gas bubbling, and were expected to react with the Mg in the Al melt which resulted in the formation of MgCl2.