Abstract: The invention relates to a process for thermally insulating precalcined anodes in cells for the production of aluminum by the electrolysis of alumina dissolved in an electrolysis bath based on molten cryolite, comprising covering the upper part of the anodes with a heat-insulating layer of alumina and/or ground electrolysis bath, in which process a strip of aluminum substantially equal in height to the heat-insulating layer is applied to the upper part of the anode and over its entire periphery.To facilitate positioning of the strip, a ledge to which the strip is applied is formed around the periphery of the anode.

Abstract: The invention concerns a process and a device for controlled feed of alumina and halogen additives into a vat for production of aluminum by alumina electrolysis according to the Hall-Heroult technique.The alumina or the halogen additive, set aside by gravity into the storage means, is introduced into a volumetric feed regulator and dispatched under the effect of a jet of compressed air, as far as the orifice of introduction into the electrolysis vat, through a rigid system of pipes, in successive equal or unequal dosed quantities, at constant or variable time intervals. The device includes no moving piece which is subject to wear or abrasion.

Abstract: A process and an apparatus is disclosed for controlling the supply of alumina of a cell for the production of aluminum by electrolysis using the Hall-Heroult process wherein each alumina supply orifice of the cell comprises a movable plunger which is electrically insulated from the superstructure of the cell and of which at least the end is electrically conducting and a means for measuring the potential between the end of the movable plunger and a point of the cell which is taken as reference potential. The plunger is moved with an alternating, substantially vertical, upward and downward movement and in each downward movement means detects whether the plunger has come into contact with molten electrolyte or with solidified electrolyte.In the first case, when molten electrolyte is detected the plunger is raised while in the second case when solidified electrolyte is detected the electrical power supplied to the cell is increased in order to remelt the solidified electrolyte.