Process and apparatus for accurately controlling the rate of introduction and the content of alumina in an igneous electrolysis tank in the production of aluminium

摘要

A process and apparatus for controlling the rate of introduction and the content of alumina to a tank for the production of aluminium by the electrolysis of dissolved alumina in a cryolite-base bath, the upper part of which forms a solidified crust, and wherein the alumina content is maintained within a narrow range, of between 1% and 3.5%, wherein the alumina is introduced directly into the molten cryolite bath by way of at least one opening which is kept open in the solidified crust and the rate at which the alumina is introduced is modulated relative to variations in the internal resistance of the tank during predetermined periods of time, with alternation of the cycles of introducing alumina at a slower rate and at a faster rate than the rate corresponding to normal consumption within the tank.