Method for operating an electrolytic cell

Abstract

A method for conveying an anode assembly outside of an electrolyte cell is described. The method allows starting up the electrolytic cell while maintaining the production of non-ferrous metal, such as aluminum or aluminium. A thermal insulation allows maintaining the anode temperature homogeneity and preventing thermal shocks when introducing the inert anodes into the hot electrolytic bath. The method allows accurate positioning of anode assemblies over the electrolysis cell before achieving mechanical and electrical connections of the anode assembly or the cell pre-heater to the electrolysis cell.

What is claimed is: 
     
         1 . A method for delivering an anode assembly of inert anodes at a given temperature to an electrolytic cell for use in producing a non-ferrous metal, comprising:
 a) preheating the inert anodes of the anode assembly at the given temperature, the anode assembly being located outside the electrolytic cell;   b) transporting the anode assembly toward the electrolytic cell while maintaining the given temperature of the pre-heated inert anodes; and   c) plunging the pre-heated inert anodes of the anode assembly into a bath of molten electrolyte of the electrolytic cell.   
     
     
         2 . The method according to  claim 1 , wherein a) of preheating the inert anodes of the anode assembly is performed into a preconditioning station located at a distance from the electrolytic cell, the method further comprising before b):
 removing the anode assembly from the preconditioning station while enclosing the anode assembly inside an insulating transportation apparatus configured to convey the anode assembly toward the electrolytic cell while maintaining the given temperatures of the inert anodes within a predetermined tolerance range.   
     
     
         3 . The method according to  claim 2 , wherein removing the anode assembly from the preconditioning station and enclosing the anode assembly in the insulating transportation apparatus comprises:
 positioning the insulating transportation apparatus over the anode assembly located in the anode preconditioner;   lowering an actuator assembly from an interior spacing of the insulating transportation apparatus to the anode assembly;   connecting the anode assembly to the actuator assembly; and   raising the actuator assembly with the anode assembly connected thereto from the anode assembly preconditioner and into an interior spacing of the insulating transportation apparatus.   
     
     
         4 . The method according to  claim 3 , wherein c) plunging the pre-heated inert anodes of the anode assembly into a bath of molten electrolyte of the electrolytic cell comprises:
 positioning the insulating transportation apparatus over the electrolytic cell;   lowering the actuator assembly and the anode assembly from the insulating transportation apparatus into the electrolytic cell until the pre-heated inert anodes are plunged inside the bath of molten electrolyte;   mechanically connecting the anode assembly to the electrolyte cell;   electrically connecting the inert anodes of the anode assembly to the electrolyte cell; and   releasing the anode assembly from the actuator assembly.   
     
     
         5 . The method according to  claim 4 , wherein lowering the anode assembly into the bath comprises registering guiding pins of the insulating transportation apparatus to respective receiving apertures of the electrolytic cell before lowering the anode assembly into the electrolytic cell. 
     
     
         6 . The method according to  claim 4 , wherein electrically connecting the inert anodes of the anode assembly to the electrolyte cell comprises mechanically bolting a flexible portion of the anode assembly onto an anodic equipotential bar of the electrolyte cell. 
     
     
         7 . The method according to  claim 2 , wherein the actuator assembly is coupled to a supporting structure of the insulating transportation apparatus, the actuator assembly comprising a handling beam configured to support the anode assembly and vertically move the anode assembly, wherein releasing the anode assembly from the insulating transportation apparatus comprises releasing the anode assembly from the handling beam, the method then further comprising:
 subsequent to releasing the anode assembly from the handling beam, raising the handling beam into the supporting structure of the insulating transportation apparatus; and   withdrawing the insulated transportation apparatus away from the electrolytic cell.   
     
     
         8 . The method according to  claim 2 , wherein the insulating transportation apparatus comprises a door assembly for thermally isolating an opening through which the anode assembly enters into and exits from the insulating transportation apparatus, the method further comprising:
 when removing the anode assembly from the anode preconditioning station and enclosing the anode assembly in the insulating transportation apparatus:
 (i) actuating the door assembly into an open position; 
 (ii) raising the anode assembly into an interior spacing of the insulated transportation apparatus; and 
 (iii) closing the door assembly; and 
   when installing the anode assembly at the electrolytic cell:
 (i) actuating the door assembly into the open position; and 
 (ii) lowering the anode assembly from the interior spacing of the insulating transportation apparatus into the electrolytic cell. 
   
     
     
         9 . The method according to  claim 2 , wherein the insulating transportation apparatus comprises:
 a supporting structure comprising an interior space configured to receive and contain the anode assembly;   an actuator assembly coupled with the supporting structure and configured to support the anode assembly, the actuator assembly being operable to move the anode assembly between:
 a thermally insulated position wherein the anode assembly is positioned in the interior spacing of the supporting structure; and 
 a loading-unloading position wherein the anode assembly is outside the supporting structure for loading the anode assembly to the actuator assembly or unloading the anode assembly from the actuator assembly; and 
   a thermic system supported by the supporting structure for maintaining a temperature of inert anodes of the anode assembly when the anode assembly is in the interior space during conveyance of the anode assembly from the anode preconditioning station to the electrolytic bath.   
     
     
         10 . The method according to  claim 9 , further comprising:
 electrically isolating the anode assembly from the actuator assembly via an electric insulation system of the actuator assembly.   
     
     
         11 . The method according to  claim 9 , wherein the supporting structure of the insulating transportation apparatus defines an open bottom in communication with the interior space, the apparatus further comprising:
 a door assembly moveably coupled to the supporting structure and operable between an open position to permit movement of the anode assembly between the insulated position and the loading-unloading position, and a closed position where the door assembly closes the open bottom of the supporting structure.   
     
     
         12 . The method according to  claim 9 , wherein the actuator assembly of the insulating transportation apparatus comprises a handling horizontal beam, the method further comprising:
 removably connecting the handling horizontal beam to the anode assembly and vertically moving the anode assembly inside the interior space.   
     
     
         13 . The method to  claim 12 , wherein the actuator assembly comprises a first motor and a second motor supported by the supporting structure, each motor being respectively coupled to a moving element arranged at opposite longitudinal ends of the handling horizontal beam along which the handling horizontal beam is vertically raised and lowered, and wherein the moving element comprises a threaded rod or a chain activated by the motor for raising or lowering the handling horizontal beam. 
     
     
         14 . The method according to  claim 12 , further comprising:
 removably engaging and supporting the anode assembly to a failsafe hanging device of the actuator assembly, wherein the failsafe hanging device engages into a corresponding handling pin of the anode assembly upon lowering of the actuator assembly onto the anode assembly.   
     
     
         15 . The method according to  claim 9 , wherein the thermic system comprises several thermal shelters extending from an inner surface of the supporting structure for interfacing with corresponding surfaces of the plurality of anodes when the anode assembly is in the interior space, and wherein the thermal shelters comprise refractory lining. 
     
     
         16 . The method according to  claim 9 , wherein the insulating transportation apparatus further comprises an electrical heater module, the method further comprising:
 heating the inert anodes using the electrical heater module when the anode assembly is in the interior space.   
     
     
         17 . The method according to  claim 9 , further comprising:
 ventilating an upper zone of the anode assembly to maintain the upper zone at a lower temperature than a lower hot zone containing the plurality of inert anodes.   
     
     
         18 . The method according  claim 9 , further comprising:
 registering guiding pins with a structure of the electrolytic cell for facilitating operative installation of the anode assembly thereinto.   
     
     
         19 . The method according to  claim 9 , further comprising:
 electrically connecting the anode assembly to the electrolyte cell via an automated connection assembly of the actuator assembly, wherein the automated connection assembly comprises a pneumatic wrench and a synchronised bolting system.   
     
     
         20 . The method according to  claim 1 , wherein the non-ferrous metal is aluminum.