Electrolysis cell and cathode with irregular surface profiling

Abstract

An electrolysis cell for the production of aluminum has a liquid aluminum layer on a cathode, a melt layer on the liquid aluminum, and an anode above the melt layer. An upper side of the cathode has surface profiling with two or more elevations provided at at least two of the twenty points of the surface of the upper side of the cathode vertically beneath those regions of the boundary surface between the layer of liquid aluminum and the melt layer in which peaks with the twenty highest maxima are present in the distribution of a reference wave formation potential in the boundary surface. The reference wave formation potential is defined as the wave formation potential which, when the electrolysis cell is operated with a reference cathode without surface profiling is present at a point in the boundary surface between the layer of liquid aluminum and the melt layer.

1 . An electrolysis cell for the production of aluminum, comprising:
 a cathode having an upper side formed with a surface profiling of two or more elevations;   during an operation of the electrolysis cell, a layer of liquid aluminum on said upper side of said cathode, a melt layer on the layer of liquid aluminum, and an anode above the melt layer;   said surface profiling of said cathode being configured and disposed in such a way that an elevation is in each case provided at two or more of twenty points of a surface of said upper side of said cathode that are in each case disposed vertically beneath those regions of a boundary surface between the layer of liquid aluminum and the melt layer in which peaks with the twenty highest maximum values are present in a distribution of a reference wave formation potential present in the boundary surface;   the reference wave formation potential being defined as a wave formation potential which, during the operation of the electrolysis cell with a reference cathode having no surface profiling being used instead of said cathode with said surface profiling, but having an otherwise identical configuration as said cathode with said surface profiling, is present at a point in the boundary surface between the layer of liquid aluminum and the melt layer.   
     
     
         2 . The electrolysis cell according to  claim 1 , wherein a respective elevation is provided in each case at at least X of Y points of the surface of said upper side of said cathode which are in each case disposed vertically beneath those regions of the boundary surface between the layer of liquid aluminum and the melt layer in which the peaks with Y highest maximum values are present in the distribution of the reference wave formation potential present in the boundary surface, and
 wherein at least one of the following is true:   Y=20 and X is selected from the group consisting of 4, 6, 10 and 14;   Y=10 and X is selected from the group consisting of 2, 3, 5 and 7;   Y=5 and X is selected from the group consisting of 1, 2, 3 and 4.   
     
     
         3 . The electrolysis cell according to  claim 1 , wherein at least one of said elevations disposed at the points of the surface of the upper side of the cathode which in each case are disposed vertically beneath those regions of the boundary surface between the layer of liquid aluminum and the melt layer in which a respective peak is present in the distribution of the reference wave formation potential present in the boundary surface has its maximum height at the point disposed vertically beneath the point of the boundary surface between the layer of liquid aluminum and the melt layer at which the peak of the distribution of the reference wave formation potential has its maximum value. 
     
     
         4 . The electrolysis cell according to  claim 1 , wherein a geometrical outer contour of at least one of said elevations is substantially similar, in plan view, to a geometrical outer contour of the respective peaks of the distribution of the reference wave formation potential in plan view. 
     
     
         5 . The electrolysis cell according to  claim 1 , wherein a geometrical outer contour of at least one of said elevations, in plan view, at least partially represents a substantial polygon with 3, 4, 5 or 6 corners or a substantial ellipsoid. 
     
     
         6 . The electrolysis cell according to  claim 1 , wherein a three-dimensional shape of at least one of said elevations is substantially similar to a three-dimensional shape of the respective peak of the distribution of the reference wave formation potential or the three-dimensional shape of the respective said elevation corresponds to the three-dimensional shape of the respective said peak. 
     
     
         7 . The electrolysis cell according to  claim 1 , wherein at least one of said elevations is upwardly tapered in vertical direction. 
     
     
         8 . The electrolysis cell according to  claim 1 , wherein said surface profiling of said cathode is irregularly configured in at least one direction. 
     
     
         9 . An electrolysis cell for the production of aluminum, comprising:
 a cathode having an upper side formed with a surface profiling of two or more elevations;   during an operation of the electrolysis cell, a layer of liquid aluminum on said upper side of said cathode, a melt layer on the layer of liquid aluminum, and an anode above the melt layer;   said surface profiling of said cathode being configured and disposed in such a way that an elevation is in each case provided at two or more of twenty points of a surface of said upper side of said cathode that are in each case disposed vertically beneath those regions of a boundary surface between the layer of liquid aluminum and the melt layer in which peaks with the twenty highest maximum values are present in a distribution of a reference wave formation potential present in the boundary surface;   the reference wave formation potential being defined as a wave formation potential which, during the operation of the electrolysis cell with a reference cathode having no surface profiling being used instead of said cathode with said surface profiling, but having an otherwise identical configuration as said cathode with said surface profiling, and with the reference cathode being disposed at a level in the electrolysis cell to provide a volume for the layer of liquid aluminum and the melt layer between said reference cathode and said anode equal to a volume provided in the electrolysis cell with said cathode with said surface profiling, is present at a point in the boundary surface between the layer of liquid aluminum and the melt layer.   
     
     
         10 . The electrolysis cell according to  claim 9 , wherein a respective elevation is provided in each case at at least X of Y points of the surface of said upper side of said cathode which are in each case disposed vertically beneath those regions of the boundary surface between the layer of liquid aluminum and the melt layer in which the peaks with Y highest maximum values are present in the distribution of the reference wave formation potential present in the boundary surface, and
 wherein at least one of the following is true:   Y=20 and X is selected from the group consisting of 4, 6, 10 and 14;   Y=10 and X is selected from the group consisting of 2, 3, 5 and 7;   Y=5 and X is selected from the group consisting of 1, 2, 3 and 4.   
     
     
         11 . The electrolysis cell according to  claim 9 , wherein at least one of said elevations disposed at the points of the surface of the upper side of the cathode which in each case are disposed vertically beneath those regions of the boundary surface between the layer of liquid aluminum and the melt layer in which a respective peak is present in the distribution of the reference wave formation potential present in the boundary surface has its maximum height at the point disposed vertically beneath the point of the boundary surface between the layer of liquid aluminum and the melt layer at which the peak of the distribution of the reference wave formation potential has its maximum value. 
     
     
         12 . The electrolysis cell according to  claim 9 , wherein a geometrical outer contour of at least one of said elevations is substantially similar, in plan view, to a geometrical outer contour of the respective peaks of the distribution of the reference wave formation potential in plan view. 
     
     
         13 . The electrolysis cell according to  claim 9 , wherein a geometrical outer contour of at least one of said elevations, in plan view, at least partially represents a substantial polygon with 3, 4, 5 or 6 corners or a substantial ellipsoid. 
     
     
         14 . The electrolysis cell according to  claim 9 , wherein a three-dimensional shape of at least one of said elevations is substantially similar to a three-dimensional shape of the respective peak of the distribution of the reference wave formation potential or the three-dimensional shape of the respective said elevation corresponds to the three-dimensional shape of the respective said peak. 
     
     
         15 . The electrolysis cell according to  claim 9 , wherein at least one of said elevations is upwardly tapered in vertical direction. 
     
     
         16 . The electrolysis cell according to  claim 9 , wherein said surface profiling of said cathode is irregularly configured in at least one direction. 
     
     
         17 . A cathode for an aluminum electrolysis cell, the cathode comprising:
 a cathode block having an upper side formed with a surface profiling on a surface of the upper side;   said surface profiling having a plurality of two or more first webs running substantially in a first direction of the cathode and at least one second web running substantially in a second direction normal to said first direction of the cathode.   
     
     
         18 . The cathode according to  claim 17 , wherein said upper side of the cathode is formed with a depression in the form of a trough having a substantial V-shape when viewed in cross-section of the cathode, and wherein said first webs and said at least one second web are disposed on a surface of said substantially V-shaped depression. 
     
     
         19 . The cathode according to  claim 18 , wherein said depression extends over at least 75% of a surface of said cathode block. 
     
     
         20 . The cathode according to  claim 18 , wherein said depression extends substantially an entire surface of said cathode block.