Preheating of electrolytic cell

Abstract

A process for preheating an electrolytic cell, which involves disposing at least one sheet of compressed particles of exfoliated graphite across at least a portion of the surface of cathode blocks in the cell.

1 . A process for preheating an electrolytic cell, comprising disposing at least one sheet of compressed particles of exfoliated graphite across at least a portion of the surface of the cathode blocks in the cell. 
     
     
         2 . The process of  claim 1 , further comprising bringing the anodes of the electrolytic cell into contact with at least one sheet of compressed particles of exfoliated graphite. 
     
     
         3 . The process of  claim 2 , wherein a current is then passed from the anodes into and through the at least one sheet of compressed particles of exfoliated graphite to resistively heat the graphite sheet and thereby preheat the electrolytic cell. 
     
     
         4 . The process of  claim 3 , wherein the electrolytic cell is preheated to temperatures of about 900° C. or higher. 
     
     
         5 . The process of  claim 4 , wherein the at least one sheet of compressed particles of exfoliated graphite has a thickness of about 0.075 mm to about 25 mm. 
     
     
         6 . The process of  claim 5 , wherein the at least one sheet of compressed particles of exfoliated graphite has a density of about 0.5 g/cc to about 1.7 g/cc. 
     
     
         7 . The process of  claim 6 , wherein at least one sheet of compressed particles of exfoliated graphite has an electrical resistivity of at least about 500 μOhm-m. 
     
     
         8 . The process of  claim 2 , wherein the at least one sheet of compressed particles of exfoliated graphite is glued to the bottom of the anode. 
     
     
         9 . The process of  claim 1 , further comprising imbedding the exfoliated graphite particles with a resistivity additive. 
     
     
         10 . The process of  claim 9  wherein the resistivity additive is selected from the group consisting of metal, polymer, synthetic graphite, alloy and combinations thereof.