Process for online power cut out of an aluminum reduction cell

Abstract

A process for online cut out of an aluminum reduction cell (pot) including the steps of leveling of the side beams of the reduction cell to around 150 mm; punching holes on both sides of the pot to ensure that the bath does not get overflow and ensure the dipping of the anodes through these punch holes; blowing air thoroughly all around the insulated shorted joints of all the risers to clean the joints from dust and large chunks of bath; applying lubricating oil to the shorted joint bolts to conform proper movement of nuts; breaking the side crust of all the four corner anodes; tapping the bath with at least one ladle; lowering the anodes such that there is no liquid overflow over the deck plate onto the catwalk; lowering of the beam by around 70 mm to 100 mm until the voltage falls below around 1.0 V-1.5 V at around 320 kA; loosening all riser bolts of the shorted joint of all the five risers using a pneumatic wrench after confirming that the anodes are dipped into the metal; removing insulated insert plates from the shorted anode riser joints and retightening all the five riser bolts using a pneumatic wrench and then taking the pot offline.

1 . A process for online cut out of an aluminum reduction cell (pot) having a bath, liquid aluminum metal, side beams, insulated shorted riser joints and anodes comprising the steps of:
 leveling the side beams to around 150 mm.   punching holes on both sides of the pot to ensure that the bath does not overflow and ensure the dipping of the anodes through these punch holes;   breaking side crust from all corner anodes;   blowing air thoroughly all around the insulated shorted joints of each riser to clean the insulated shorted joints of dust and chunks of bath;   applying lubricating oil to joint bolts to conform proper movement of nuts;   tapping with at least one ladle of the bath;   Lowering of the anodes such that there is no liquid overflow;   lowering of beams by around 70 mm to 100 mm until voltage falls below 1.0 V-1.5 V at around 320 kA;   Loosening all riser bolts of the insulated shorted joints of all risers after confirming that the anodes are dipped into metal; and then   removing insulating insert plates from the insulated shorted joints;   Taking the pot offline.   
   
   
       2 . The process as claimed in  claim 1 , wherein at least six holes are punched on both sides of the pot. 
   
   
       3 . The process as claimed in  claim 1 , wherein the tapping is done using a second ladle. 
   
   
       4 . The process as claimed in  claim 1 , wherein 5-6 tons of liquid bath is tapped out ensuring the anodes are dipped into metal. 
   
   
       5 . The process as claimed in  claim 1 , wherein each of four corner anodes are broken so that the anodes have free movement during lowering of the anodes. 
   
   
       6 . The process as claimed in  claim 1 , wherein constant vigil is made over the anodes so that they are dipped into metal with a long crowbar through the punched holes. 
   
   
       7 . The process as claimed in  claim 1  wherein a gap is introduced at the insulated shorted joint of a riser by means of a short crow bar so that insulated insert plates can be removed. 
   
   
       8 . The process as claimed in  claim 1 , wherein insulated wooden wedges are introduced between the insulated shorted joints so that the insulated shorted joints do not short with each other. 
   
   
       9 . The process as claimed in  claim 1 , wherein thorough cleaning of contact surfaces of the insulated shorted joint is performed. 
   
   
       10 . A method for taking an aluminum reduction cell offline without affecting operation of other reduction cells in series with said cell comprising the steps of:
 leveling side beams of said cell to around 150 mm;   punching holes on both sides of said cell to prevent overflow;   tapping a quantity of liquid bath from said cell;   lowering anodes into metal in the said cell;   lowering said beams by around 70 mm to 100 mm until voltage falls to between around 1.0 V. to 1.5 V.;   loosening all riser bolts;   removing insulating insert plates from insulated shorted anode risers;   taking said cell offline.   
   
   
       11 . The method as claimed in  claim 10  wherein a gap is introduced at the insulated shorted anode joint of a riser by means of a short crow bar so said insulated insert plates can be removed. 
   
   
       12 . The method as claimed in  claim 10 , wherein each of four corner anodes are broken so that the anodes have free movement during lowering of the anodes. 
   
   
       13 . The method as claimed in  claim 10 , wherein 5-6 tons of liquid bath is tapped out ensuring the anodes are dipped into said metal. 
   
   
       14 . The method as claimed in  claim 10  wherein a final current of around 320 kA is maintained. 
   
   
       15 . The method as claimed in  claim 10 , wherein at least six holes are punched on both sides of the cell.