Density of Na3AIF6-AIF3-LiF-MgF2-Al2O3-Sm2O3 molten salt melt for Al-Sm alloy

Samarium(Sm) has been widely used in making aluminum(Al)-Sm magnet alloy materials. The research team for this study developed a molten salt electrolyte system which directly produces AI-Sm alloy to replace the energy intensive conventional distillation technology. In this study, molten melt density was measured and operation conditions were optimized to separate AI-Sm alloy product from the fluoride molten melt electrolysis media based on density differences, Archimedes’ principle was applied to measure density for the basic molten fluoride system(BMFS: NaAlF-AlF-LiF-MgF)electrolysis media in the temperature range from 905 to 1055 ℃.The impact of temperature(t) and the AlOand SmOaddition ratio(w(Al2O3)),w(Sm2O3)) in the basic fluoride system on molten melt density was examined. The fluoride molten melt density relationship was determined to be:ρ=3.11701-0.00802 w(Al2O3))+0.027825 w(Sm2O3))-0.00117 t. The test results showed that molten density decreases with increase in temperature and AlOaddition ratio, and increases with the addition of SmO, and/or AlO+SmO. The separation of Al-Sm(density 2.3 g/cm~3) product melt from the BMFS melt is achieved by controlling the BMFS density to less than 2.0 g/cm3. It is concluded that the optimal operation conditions to control the BMFS molten salt density to less than 2.0 g/cm~3 are:maintain addition of AlO+SmO(w(Al2O3))+w(Sm2O3))<9% of NaAlF,AlO/SmOratio(w(Al2O3)):w(Sm2O3)))> 7:3, and temperature between 965 and 995 ℃.