A modified electrolysis cell and a method for modifying same

A method for reducing the metal pad unevenness and optimizing the magnet hydrodynamic stability in an electrolysis cell of the Hall-Heroult type for aluminium production, and a correspondingly modified cell. The cell has suspended prebaked anodes and a cathode panel. The panel comprises several cathode blocks or cathode block sections. A metal pad and an electrolytic bath are located between said anodes and the cathode panel. The force field acting on the metal pad is calculated and monitored in a computer based model of the cell, whereby the local current paths and correspondingly the local forces in the metal above the cathode panel are modified by influencing selectively the current distribution in individual cathode blocks or block sections in the computer based model. The result is a reduction in the unevenness of the metal pad and an enhancement of the overall magnet hydrodynamic stability of the cell.