Numerical calculation and industrial measurements of metal pad velocities in Hall-Heroult cells

The Navier-Stokes equation with the "k-ε" two-equation turbulence model was employed to describe three-dimension flow of melt in aluminum electrolysis cells. For a 160 kA cell with two current risers, the source, i.e. the electromagnetic force, in the momentum equations was solved based on the simulation results of magnetic and temperature fields. Numerical simulation on the three-dimension steady-state flow of melt was carried out. The results obtained about the velocities of molten metal on different planes, the metal/bath interface shape and the electromagnetic force distribution, were analyzed. An iron rod dissolution technique, which is based on the rate of dissolution of iron rods inserted into the melt, was used to measure the velocities of metal pad. The simulation and measurement show that there are two interaction vortexes in horizontal direction. The predictions are in well agreement with the measured results for flow pattern and velocities. It is worthwhile that in the three-dimension simulation, there is also a little change of metal velocities from level to level due to the difference of horizontal current on each level.