Mineral Composition and Phase Transformations in the Refractory Lining of the Bottom of Aluminum Electrolysis Cells. Part 1.

Results for specimens of the refractory lining sampled from the bottom of an aluminum electrolysis cell with a service life of 3.5 years examined by methods of petrography, chemical analysis, and electron probe x-ray microanalysis are reported. The main products of conversion are sodium aluminosilicates, sodium silicates, a glassy phase of variable composition, oxyfluoride glasses, and eutectics. Some of the specimens analyzed are high in β-alumina (20 – 50%). Fluorides are represented by NaF (about 7%), cryolite Na₃AlF₆ (2 – 5%), malladrite Na₂SiF₆ (2%), and NaF ⋅ MgF₂ (1 – 2%), and the metallic phase, by aluminum (2 – 7%) and ferrosilicon (3 – 10%). The apparent density of the used refractory material is 2.5 – 2.62 g/cm³. __________ Translated from Novye Ogneupory, No. 3, pp. 13 – 17, March, 2005.