In this paper it is shown that pneumatically injected gaseous mixtures containing SF_6(g) are useful to oxidize the magnesium dissolved in molten aluminum alloys. Although the oxidation of magnesium with SF_6(g) is thermodynamically favorable, the addition of O_2(g) causes that AG is additionally reduced by -249.16 KJ/mo1 Mg. After chemical analysis of the final contents of magnesium in the treated alloys, the identification of compounds in the slag by x-ray diffraction, and chemical analysis of gaseous emissions produced, a scheme of reaction is proposed considering no emission of volatile fluorides or sulfides. Kinetic equations describing the magnesium removal rate are presented, taking into account that kinetics of the process is controlled by chemical reaction.
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