Purification of Aluminum melt in Crucibles by Bubble Flotation

Abstract According to the principle of bubble floatation, purification of A356 aluminum casting alloy has been studied by purging nitrogen gas into the A356 alloy melt through a patented porous sprayer which is immerged in the molten aluminum and can generate a large quantity of dispersed micro bubbles to absorb the hydrogen and carry the nonmetallic inclusions in the melt to the surface of the melt. The experiments have been carried out in different capacity of crucibles for the assessment of the evaluation of effectiveness. 5 samples were taken at 0 min, 2 min, 4 min, 6 min, 8 min and 10 min, respectively, to measure the hydrogen content through HYSCAN Ⅱ hydrogen tester in the temperature of 720C. The experiments results show that the removing effects of hydrogen and oxide inclusion are remarkable. The hydrogen contents reach the minimum when purging lasts 10, 8 and 4 minutes for the 280kg, 160kg and 40kg, respectively. The inclusions are also removed along with the removal of hydrogen.