Removal of magnesium from molten aluminum scrap by compound-separation method with Shirasu

Abstract

The removal of magnesium from the molten aluminum scrap containing magnesum was examined by compound-separation method using Shirasu as an additive. When Sirasu is added to the molten aluminum scrap, which is followed bggy agitation, MgAl2O4 and MgO are formed by the reactions among SiO 2 and Al2O3 in Shirasu and magnesium in the molten scrap. It is feasible to remove magnesium by separating these recation products as dross. The effect of addition temperature of Shirasu on magnesium removal is smaller than that of the agitation time. In the cases of the addition of flaky Shirasy with 63-150 μm of particle size, the amount of magnesium removed increases linearly with agitation time because the over all recation is mainly controlled by a surface size, the amount of magnesium remove increases linearly with agitation time 590 μm of particle size, the amount of magnesium removed increases parabolically with agitati8on time because the over-all reaction is mainly controlled by a diffusion-controlled recation. The amount of magnesium removed can be controlled by changing the amount of Shirasu added. © 2010 The Japan Institute of Metals.