Influence of B2O3 on viscosity and structure of the CaO–Al2O3-waste electrolyte (WE) based melt

Abstract

The fluorides contained waste electrolyte (WE) from the electrolytic aluminum industry can be used as a substitution of fluorite (CaF2) in the newly designed mold flux. In this study, the influence of B2O3 on viscosity and structure of CaO–Al2O3-WE based melt was investigated. Results show that the viscosity of mold flux melt decreases with both increasing temperature and B2O3 content. The apparent activation energy (Ea) also reduces from 78.96 ± 1.75 to 55.26 ± 2.79 kJ/mol with the addition of B2O3 from 0 to 7 wt%. The analyses of fourier transform infrared (FTIR) and Raman spectroscopies suggest that the lower symmetry of the original aluminate and silicate structure due to the insertion of [BO4]-tetrahedral and [BO3]-triangular, and the formation of more non-bridging oxygen (O−) and 2D structural units in the network with the addition of B2O3, deceases the viscosity and Ea of the CaO–Al2O3-WE Based Melt.