FLUX FOR REMOVING ALKALI METAL AND ALKALINE EARTH METAL FROM MOLTEN ALUMINUM

摘要

PURPOSE:To remove efficiently alkali metals and alkaline earth metals from molten Al or a molten Al alloy while minimizing the emission of harmful gases by using aluminum ammonium fluoride as a removing agent. CONSTITUTION:A flux contg. aluminum ammonium fluoride as the base is brought into contact with molten Al or a molten Al alloy. Aluminum ammonium fluoride is obtd. by a known method. For example, AlCl3 is added to an aqueous ammonia soln. or hydrofluoric acid, and neutralization is carried out with hydrofluoric acid or an aqueous ammonia soln. to deposit aluminum ammonium fluoride. When the amount of the ammonia soln. is increased, aluminum ammonium fluoride contg. a relatively large amount of (NH4)3AlF6 is obtd. The fluoride is used in the form of powder, granules or a cake, and it reacts with alkali metals and alkaline earth metals in the molten metal to float and remove the metals as fluorides.