Process and apparatus for refining aluminum

In a process for refining aluminum using a segregation solidification process under an atmosphere of positive pressure inert gas and including the steps of pouring molten aluminum into a vessel, heating said vessel to maintain the molten aluminum at an appropriate temperature, partially crystallizing said molten aluminum by a cooling surface area located in said vessel to form primary crystals of aluminum onto said cooling surface area, scraping off the refined and solidified aluminum from said area to form a heap on the bottom of said vessel, tamping the deposited heap to press out the impure liquid existing within the heap of the solidified aluminum upwardly of the level of the tamped aluminum, removing the liquid existing above the thus tamped heap of aluminum, and taking out said tamped aluminum from said vessel, the improvement comprising maintaining an appropriate temperature of the molten aluminum in said vessel by means of a plurality of electric heater means arranged around the periphery of said vessel in vertically superposed relationship to each other, cooling a narrow peripheral portion of the inner surface of said vessel beneath the level of the molten aluminum therein by peripheral cooling means arranged around the periphery of said vessel between adjacent two heater sections to crystallize the molten aluminum onto said peripheral portion of the inner surface of said vessel, scraping off refined and solidified aluminum on said peripheral portion by scraping and tamping means having a cross-sectional configuration substantially complementary to that of the inner surface of said vessel, tamping the heaped aluminum by said scraping and tamping means, and deenergizing some of said heater sections located at positions around the solidified heap of aluminum.