Graphitized cathode block for aluminum smelting

Abstract

The present invention provides a graphitized cathode block for aluminum smelting obtained by forming a raw material containing at least one calcined coke selected from the group consisting of calcined petroleum coke and calcined pitch coke, and a binder; baking the formed material to give a non-graphitized block; and graphitizing the non-graphitized block by resistive heating; wherein both end portions of the block have a higher electrical resistivity than the center portion thereof. By employing the cathode block of the present invention, during electrolytically smelting aluminum, current may be uniformly flowed as the concentration of current at both end portions of the cathode block is lightened, and it becomes possible to maximize the advantages of graphitized cathode blocks.

What is claimed is:  
     
         1 . A graphitized cathode block for aluminum smelting obtained by forming a raw material containing at least one calcined coke selected from the group consisting of calcined petroleum coke and calcined pitch coke, and a binder; baking the formed material to give a non-graphitized block; and graphitizing said non-graphitized block by resistive heating; wherein both end portions of the block have a higher electrical resistivity than the center thereof.  
     
     
         2 . A graphitized cathode block for aluminum smelting according to  claim 1 , wherein the electrical resistivity of the block center is within a range of 8 to 17 μΩm, and the electrical resistivities of the portions up to at least 15% of the entire block length from both ends of the block are respectively higher than that of the block center by 0.5 to 3 μΩm and within a range of 8.5 to 20 μΩm.  
     
     
         3 . A method of manufacturing the graphitized cathode block according to  claim 1  or  claim 2 , comprising the steps of: 
 forming a raw material containing at least one calcined coke selected from the group consisting of calcined petroleum coke and calcined pitch coke, and a binder;  
 baking the formed material to give a non-graphitized block;  
 serially connecting two or more of said non-graphitized blocks and arranging a current distributor(s) at the periphery of the contact portion(s) of the blocks; and  
 applying an electric current to the non-graphitized blocks to produce a graphitized block.  
 
     
     
         4 . A method of manufacturing the graphitized cathode block according to  claim 3 , wherein said current distributor is composed of graphite plates fixed at the periphery of the contact portion of the blocks.  
     
     
         5 . A method of manufacturing the graphitized cathode block according to  claim 4 , wherein said current distributor is composed of graphite plates each having a thickness of 5 to 15 cm, a length capable of covering a portion up to at least 15% of the entire block length from the block end, and a width that is 90 to 98% of the width of the non-graphitized block.