ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Physicochemical analysis of some systems important in the production of aluminum. VI. Liquidus of the cryolite angle of the system Na₃AlF₆-AlF₃-Al₂O₃-CaF₂-NaCl

K. Matiašovský and M. Malinovský

Slovak Academy of Sciences, Bratislava

Abstract: By thermal analysis and by a visual method the cryolite angle of the system Na₃AlF₆-AlF_3-Al₂O₃-CaF₂-NaCl was studied, and the effect of the addn. of NaCl on the fusion of the electrolyte and the soly. of Al₂O₃ was detd. Liquidus diagrams of 4 cuts of this system, each contg. 3.0% CaF_2, at cryolite ratios 2.75, 2.50, 2.25, and 2.00 were constructed. By evaluating the cut at cryolite ratio 2.50. it was detd. that the addn. of 1.0% NaCl decreases the crystn. temp. of the fusion in the area of the primary crystn. by 4-5°; this is more effective than the conventional addn. of AlF₃ (2-3°/1.0% AlF₃). The addn. of NaCl decreases the soly. of Al₂O₃ in the electrolyte, but the dependence of the decrease on the concn. of NaCl in the fusion is not linear. The decrease is relatively higher at higher NaCl concns. The decrease of soly. of Al₂O₃3 produced by the addn. of 1.0% NaCl is, at 950°, approx. 0.2% Al₂O₃, as compared with approx. 0.3% Al₂O₃ with the addn. of 1.0% AlF₃.

Full paper in Portable Document Format: 154a257.pdf (in Slovak)

Chemical Papers 15 (4) 257–270 (1961)