Cermet inert anode assembly thermal insulating layer

Abstract

A method for protecting anode assemblies in an electrolytic cell from thermal shock is disclosed. The method generally involves applying a thermal insulating layer ( 8, 16 ) to the anode ( 2 ) and the castable plate ( 4 ) prior to preheating the anode assembly in a furnace, where the layer ( 8, 16 ) protects the anode ( 2 ) and the plate ( 4 ) from thermal shock during transfer from the preheat furnace to the electrolytic cell.

What is claimed is:  
     
         1 . A method for protecting an inert anode from thermal shock comprising: 
 (a) applying a thermal insulating layer to said inert anode;    (b) heating said anode; and    (c) transferring said heated anode to an electrolytic cell.    
     
     
         2 . The method of  claim 1 , wherein said inert anode is a ceramic inert anode.  
     
     
         3 . The method of  claim 1 , wherein said inert anode is a cermet inert anode.  
     
     
         4 . The method of  claim 1 , wherein said thermal insulating layer comprises a silica material.  
     
     
         5 . The method of  claim 1  wherein said thermal insulating layer is comprised of more than one material, with the outer most material being more durable than any of the other materials.  
     
     
         6 . The method of  claim 1 , wherein said application is by physical attachment using wire, ceramic string or cloth, and the anode is heated in a furnace.  
     
     
         7 . The method of  claim 1 , wherein said thermal insulating layer is about 2 inches thick or less.  
     
     
         8 . The method of  claim 1 , wherein said heating step is effected at a rate of between about 15° C. and 45° C. per hour.  
     
     
         9 . The method of  claim 1 , wherein said electrolytic cell is used in the production of aluminum, and after step (c) the anode and insulating layer are inserted into an electrolyte after which the insulating layer is dissolved off the anode.  
     
     
         10 . The method of  claim 1 , further comprising protecting a castable plate to which the anode is attached by applying a thermal insulating layer to said plate, wherein the thermal insulating layer attached to the plate is the same or different than the thermal insulating layer attached to the anode.  
     
     
         11 . The method of  claim 10 , wherein said thermal insulating layer applied to said plate comprises a silica material.  
     
     
         12 . The method of  claim 10 , wherein said thermal insulating layer applied to said plate is comprised of more than one material, with the outer most material being more durable than any of the other materials.  
     
     
         13 . The method of  claim 10 , wherein said thermal insulating layer applied to said plate is about 2 inches thick or less.  
     
     
         14 . The method of  claim 10 , wherein said electrolytic cell is used in the production of aluminum.  
     
     
         15 . The method of  claim 10 , wherein said castable plate is comprised of a silica ceramic material, an alumina ceramic material or mixtures thereof.  
     
     
         16 . An inert anode covered at least in part with a thermal insulating layer.  
     
     
         17 . The inert anode of  claim 16 , wherein said layer comprises a silica material.  
     
     
         18 . The inert anode of  claim 16 , wherein said layer is about 2 inches thick or less.  
     
     
         19 . The inert anode of  claim 16 , wherein said layer is physically attached to said anode by wire, ceramic string or cloth.  
     
     
         20 . An anode assembly comprising 
 a plurality of inert anodes covered at least in part with a thermal insulating layer; and    a plate to which said inert anodes are attached covered at least in part with a thermal insulating layer; wherein the thermal insulating layer attached to the plate is the same or different than the thermal insulating layers attached to the anodes.