Process For Changing an Anode In an Electrolytic Aluminium Production Cell Including Adjustment of the Position of the Anode and Pot Tending Machine For Implementing It

Abstract

The purpose of the invention is a process for changing an anode of a cell for the production of aluminium by fused bath electrolysis ( 2 ) on which at least one anode handling tool ( 13 ) is used, comprising a positioning device ( 13 b ) and a gripping device ( 13 a ), and characterised in that during replacement operations of a determined spent anode ( 20 ′) by a replacement anode ( 20 ″), the position of the replacement anode ( 20 ″) is determined from a determined set of measurements of a fixed point position Po located on at least one anode handling tool ( 13 ) with respect to a determined set of reference points P located on determined objects separate from the anode handling tool. Another purpose of the invention is a pot tending machine used to implement the process. The invention significantly limits the handling operations required to determine the position of the replacement anode.

1 . Process for changing an anode of a cell for the production of aluminium by fused bath electrolysis comprising an anode frame and a plurality of anodes ( 20 ), each fitted with a metal stem, wherein, using at least one anode handling tool comprising a positioning device and a gripping device, at least one determined spent anode is replaced by at least one replacement anode and the replacement anode is positioned in a determined position in the electrolytic cell, the said process being characterised in that:
 for at least one anode handling tool, a fixed point Po firmly fixed to the said tool is chosen;   a determined set of intermediate reference positions of an anode handling tool is chosen and each position of the said set is associated with an intermediate reference point located on determined objects separate from the anode handling tool;   a final reference position of an anode handling tool corresponding to the said determined position of the replacement anode is chosen, and this reference position is associated with a final determined reference point P F  located on a determined object separate from the anode handling tool;   the anode handling tool is placed in each of the said intermediate reference positions, and for each position the relative position of the fixed point Po of the tool with respect to the corresponding intermediate reference point is measured;   a final relative position of the fixed point Po of a handling tool with respect to the determined final reference point P F  corresponding to the said determined position of the replacement anode in the electrolytic cell, is determined from the said relative position measurements;   the position of the replacement anode is adjusted using at least one measurement of the relative position of the fixed point Po of a handling tool with respect to the final reference point P F  so as to position the said tool in the said final relative position.   
     
     
         2 . Process according to  claim 1 , characterised in that the final reference point P F  is located on the electrolytic cell. 
     
     
         3 . Process for changing an anode according to  claim 2 , characterised in that the final reference point P F  is located on the anode frame of the electrolytic cell. 
     
     
         4 . Process for changing an anode according to  claim 1 , characterised in that the said final relative position is a gripping position of the metal stem of the replacement anode. 
     
     
         5 . Process for changing an anode according to  claim 1 , characterised in that the said determined set of intermediate reference positions comprises:
 a first reference position A with respect to the metal stem of the spent anode, before withdrawing it from the electrolytic cell;   a second reference position B with respect to the metal stem of the spent anode, after having withdrawn it from the electrolytic cell and having placed it on a reference object;   a third reference position C with respect to the metal stem of a replacement anode, after having placed it on a reference object.   
     
     
         6 . Process for changing an anode according to  claim 5 , characterised in that the first and second reference positions are gripping positions of the metal stem of the spent anode and the said third reference position is a gripping position of the metal stem of the replacement anode. 
     
     
         7 . Process for changing an anode according to  claim 5 , characterised in that the intermediate reference point P A  associated with the first reference position A is located on the electrolytic cell. 
     
     
         8 . Process for changing an anode according to  claim 7 , characterised in that the intermediate reference point P A  is located on the anode frame. 
     
     
         9 . Process for changing an anode according to  claim 7 , characterised in that the said determined final reference point P F  is the same as the intermediate reference point P A  associated with the first reference position A. 
     
     
         10 . Process for changing an anode according to  claim 5 , characterised in that the intermediate reference point P B  associated with the second reference position B is located on a first reference object located outside the electrolytic cell. 
     
     
         11 . Process for changing an anode according to  claim 10 , characterised in that the reference object is an anode transport pallet. 
     
     
         12 . Process for changing an anode according to  claim 5 , characterised in that the intermediate reference point P C  associated with the third reference position C is located on a second reference object located outside the electrolytic cell. 
     
     
         13 . Process for changing an anode according to  claim 12 , characterised in that the reference object is an anode transport pallet. 
     
     
         14 . Process for changing an anode according to  claim 1 , characterised in that the same handling tool is used to handle the spent anode and the replacement anode and for carrying out the said relative position measurements. 
     
     
         15 . Process for changing an anode according to  claim 1 , characterised in that the said relative positions are given by a distance D between a fixed point Po and a reference point and the spatial orientation S of the reference point with respect to the fixed point Po. 
     
     
         16 . Process for changing an anode according to  claim 15 , characterised in that the reference positions and the corresponding reference points are chosen such that the said spatial orientation S is substantially the same for all relative position measurements. 
     
     
         17 . Process for changing an anode according to  claim 1 , characterised in that the said measurements are made by telemetry. 
     
     
         18 . Process for changing an anode according to  claim 17 , characterised in that the said telemetry is chosen from among optical, acoustic and radioelectric telemetries. 
     
     
         19 . Process for changing an anode according to  claim 18 , characterised in that the said telemetry is a laser telemetry. 
     
     
         20 . Process for changing an anode according to  claim 1 , characterised in that the fixed point Po is located on the gripping device or on an element of the handling tool fixed to the gripping device. 
     
     
         21 . Pot tending machine intended for anode replacement operations in a series of cells for the production of aluminium by fused bath electrolysis comprising a plurality of anodes each provided with a metal stem, the said machine comprising at least one anode handling tool comprising a positioning device and a gripping device, characterised in that it comprises a device for measuring the position of a fixed point Po located on the anode handling tool with respect to at least one determined reference point P located on a determined object separate from the anode handling tool. 
     
     
         22 . Pot tending machine according to  claim 21 , characterised in that the fixed point Po is located on the gripping device or on an element of the handling tool fixed to the gripping device. 
     
     
         23 . Pot tending machine according to  claim 21 , characterised in that the measurement device comprises a telemeter to make the said measurement. 
     
     
         24 . Pot tending machine according to  claim 23 , characterised in that the telemeter is chosen from along optical, acoustic or radioelectric telemeters. 
     
     
         25 . Pot tending machine according to  claim 24 , characterised in that the telemeter is a laser telemeter. 
     
     
         26 . Pot tending machine according to  claim 21 , characterised in that the measurement device is fixed to the gripping device or to an element fixed to the gripping device. 
     
     
         27 . Pot tending machine according to  claim 21 , characterised in that the anode handling tool is provided with a means of measuring the tension in the tool, such as an axial dynamometer. 
     
     
         28 . Pot tending machine according to any  claim 21 , characterised in that the measurement device comprises a system to record the measurements made and to determine the said position A′ corresponding to the replacement anode. 
     
     
         29 . Pot tending assembly for a plant for the production of aluminium by fused bath electrolysis comprising a travelling crane and at least one pot tending machine according to  claim 21 .