Sub-cathode shield comprising deformable areas for Hall-Héroult electrolytic pots

摘要

The invention relates to a metallic steel screen, intended to prevent the infiltration of the metal and of the constituents of the electrolysis bath into the refractory and heat-insulating lining of the casing of a tank for the production of aluminum by the Hall-Heroult process. , this screen being placed under the base of the carbon blocks constituting the cathode of the electrolytic cell and in which the cathode bars are sealed, and extending at least over the entire space located below the cathode. It is constituted by at least one continuous steel sheet such as (6) or (19) of which at least half of the surface consists of a part having at least 5 mm, and preferably from 8 to 12 mm thickness, and which comprises at least one deformable zone absorbing the stresses due to temperature differences between the central part, located directly above the cathode, and the peripheral part. The deformable zone can be constituted either by a closed (11) or open profile, with a wall thickness less than the thickness of the thick steel sheet (6) or (9), or by a steel sheet ( 21) of thickness less than the thickness of the thick screen (19), disposed at the periphery of said screen, extending in the zone situated substantially outside the vertical alignment of the cathode blocks (1), connected with a thick screen such as (19) by a continuous weld (22), and having a cold (20 ° C) elongation before rupture greater than 2%.