A very high percentage of Aluminium produced in the United States is processed using the Hall-Heroult Cell. In this process, the Aluminium oxide is broken into melted cryolite electrolytes which are reduced to metal in an electrolytic way. The electricity of approximately 11.4 Gigawatts is used in this process and this creates a need to improve the productivity of the cell.
Figure 1 indicates part of a cell in the process of producing Aluminium. From this, it is visible that cryolite in the molten state is a float in a mass of liquid Aluminium. Carbon anode deeps into the cryolite while the cathode is made from the surface of the molten Aluminium, at this point the metal is formed and carbon dioxide is produced by the anode reaction. The productivity of the cell is highly altered by the electromagnetic force inside the liquid Aluminium and cryolite. Under perfect conditions, a cell would carry a current of between 100 and 200 kA principally moving downwards from the positively charged to the negatively charged electrodes. This current, alongside the currents in the adjoining cell apparatus, produces a high level of the magnetic field of up to 10mT moving in a parallel direction. The coming together of these currents and magnetic fields with speeds of about 10cm/s results in the circulation of the Aluminium metal and the cryolite. The circulation, on the other hand, leads to wearing out of the lining in the carbon cell and the same effect reduces current productivity of the cell.