Production of extreme purity aluminum

摘要

A process for purifying impure aluminum comprises introducing the impure aluminum to the anode layer of an electrolytic cell of the type having a bottom layer of molten aluminum-copper alloy constituting the anode layer and having a top layer of molten aluminum constituting a cathode layer, the cathode and anode layers separated by an electrolyte layer. Aluminum is electrolytically transported from the anode to the cathode in a first purification step and then fractionally crystallized to remove further impurities therefrom by crystallizing pure aluminum and thereafter separating the molten remaining part, which is high in impurities, from the purified aluminum. The impure molten aluminum portion is then recycled back to the electrolytic cell or to another fractional crystallization step.