Removal of Impurity Fe from Mg-3 mass% Al Alloy Melt by CO₂ Injection

Abstract

The purification process is required for recycling Mg process. Selective impurity removal has an efficient purification process in the purity level of commercial Mg metal and alloys. Especially, iron impurity deteriorates the corrosion resistance of Mg alloys. Carbon addition to Mg-3 mass% Al alloy melt is an effective method for the removal of iron impurity by the formation of Fe-Al-C compounds. In this study, gas injection of carbon dioxide (CO₂) into Mg alloy melt as the method of carbon addition was investigated for the separation of iron compounds. Carbon dioxide was decomposed by Mg melt and carbon substance affected the formation of iron carbide in the melt. Magnesium oxide and Fe-Al-C compound were formed in the melt slag and floated to the top of the solidified Mg-3 mass%Al alloy.