Elimination of Fe in Al-Si cast alloy scrap by electromagnetic filtration

Fe in Al-Si cast alloy scrap melt was eliminated by electromagnetic filtration of primary iron-rich phases, which were formed by adding Mn in the melt. The principle of electromagnetic filtration is that the electromagnetic force scarcely acts on the primary iron-rich phases due to its low electric conductivity as compared to the melt. As a result, a repulsive force exerts on the primary iron-rich phases to move them in the direction opposite to that of the electromagnetic force. It has been found that the forming temperature of primary iron-rich phase increases gradually with the increment of ratio of Mn to Fe (Mn/Fe), and that the iron-rich phases are formed as primary phases, they appear as massive particles with size of 30–80 μm. Experimental results show that the primary iron-rich phases are separated from Al-Si alloy scrap melt and are collected in the electromagnetic separation chamber. Fe content in the cast ingot decreases from 1.20% to 0.41% by electromagnetic filtration, which can meet the demand for casting. This new technique is highly efficient and available for continuous processing compared with natural settling and filtration methods. It offers a possibility for recycling high quality aluminum alloys.