Removal of Impurities in Aluminum by Uses of Fluxes

Abstract

A new method for removal of impurities in pure molten aluminum has been presented in this paper. The basic principle of this method is that the molten fluxes are forced to inject into the molten aluminum under counter-gravity, creating strong vortex to mix fully with the molten aluminum. In this way, the impurities in the aluminum will transfer into the flux because of the absorption of the flux to the inclusions. As the result, the molten aluminum is purified. The experiments were carried out for pure aluminum combined with the flux (40wt.% NaCl，30wt.% KCl，10wt.% NaF and 20wt.%Na3AlF6). The results show that after 3 purifying cycles (6 minutes), the inclusion contents decreased from 2. 1% to 0.35%, a removal rate of 83.3%; and hydrogen concentration decreased from 0.37ml/100gAl to 0.12ml/100gA, with hydrogen removal rate being 68%.