Abstract: Provided is a method for preparing high-purity aluminum by directional solidification, comprising the steps of: providing 4N to 5N aluminum as raw material, heating the same to a temperature of 670° C. to 730° C., maintaining the temperature for 7 minutes to 80 minutes, cooling the bottom of chamber (3) to allow the aluminum liquid crystallizing in a direction from the bottom to top of the chamber (3) for 1 hour to 8 hours to obtain a crystalline ingot, during the crystallization process of a finished product of crystalline ingot, stifling and heating the aluminum liquid, maintaining a particular temperature gradient of the aluminum liquid, and removing a portion of the crystalline ingot from one end of the ingot, the remaining portion being the high-purity aluminum. Also provided is a smelting furnace, comprising a shell (1), a heating device (2), a chamber (3), a temperature measurement device, a stirring device and a cooling device (6).

Abstract: A manufacturing method of an anode foil for an aluminum electrolytic capacitor is provided, which comprises a first step of forming a porous oxide film, i.e. subjecting an etched foil having etched holes thereon to an anodic oxidation process to form a porous oxide film on both the outer surface of the etched foil and the inner surface of etched holes, and a second step of forming a dense oxide film, i.e. converting the porous oxide film into the dense oxide film. The method can be used to manufacture an anode foil for various voltage ranges, e.g. an ultra-high voltage anode foil whose voltage is more than 800 vf, and the method can increase specific capacity, reduce power consumption, simplify the process, and increase production efficiency.