How pot insulation ages - from an insulation supplier's point of view

摘要

Skamol has examined spent pot lining from some 15 melters, and is developing laboratory tests to study changes in its insulation materials during their lifetime. Insulation materials are essential in the Hall-Heroult electrolysis cells to maintain the desired heat balance so as to produce aluminium cost-efficiently. The insulation materials must resist the thermo-mechanical stresses when the cathodes and barrier layer start to swell and heave due to sodium diffusion and bath exposure. Furthermore, they must also resist the harsh chemical environment of the electrolysis process when e.g. bath components and molten aluminium react. Especially sodium and fluorine are critical reactant species when migrating as vapours into the insulation layers before the viscous magma/barrier layer forms.