| 摘要 |
<p>The invention relates to a barrier layer (21) for prevention of solid fluorides (e.g. NaF) penetration from the interior of an aluminum production cell, or like container, holding a fluoride-containing melt into a refractory layer (17) intended to provide heat insulation for the cell or container. The barrier layer (21) comprises CaO, which may be derived from a CaO precursor such as calcite (CaCO2) by decomposition during cell start-up. Since the CaO does not react with sodium fluoride (NaF), it is effective for preventing the penetration of that compound when the latter is in the solid state. The barrier layer makes it possible to use insulating low cost refractories (17) which are attacked by solid fluorides in the cell or container wall lining with improvement of the life of such materials. The barrier layer also keeps fluorides out of the refractory materials so that these materials can be disposed of in conventional land-fill sites without risk of causing pollution due to leaching of fluoride salts.</p> |
