Study on phase and physical properties of molten salt system for chlorination of titanium slag

The molten salt chlorination method is a technique developed specifically for the preparation of titanium tetrachloride using high-calcium magnesium titanium slag materials. During long-term production practices, it has been observed that improper control of the composition in the chlorination furnace can lead to severe foaming of the molten salt, which in turn can result in issues such as salt spray that negatively impact production. To address this issue, a comprehensive study was conducted to investigate the composition, phase, and physical properties of both normal and foaming chlorination salts using analytical techniques including XRD, SEM & EDS, and DSC-TGA. The results reveal that the foaming salt has a significantly higher oxygen content and a greater presence of insoluble solid phase components compared to the normal salt. The insoluble solid phase components primarily consist of compound oxides such as Na₂Al_0.5Fe_9.5O₁₅ and Mg_1.6Ti_1.1O₄. Additionally, the foaming salt exhibits a weight loss rate of 48.71% in the temperature range of 300~1280 °C, which is 13.73% lower than that of the normal salt. Furthermore, the melting point of the foaming salt shows an increasing trend. The oxygen content in foam salt is about 10% higher than that of normal salt. After volatilization at high temperatures, the residue is irregular particle agglomerates rich in iron, magnesium, aluminum, silicon, calcium, oxygen, and other elements, while the residue of normal salt is a dense body of uniform iron, magnesium, and oxygen elements. Traditional Archimedean methods are unable to accurately measure the density of both normal and foaming salts due to the presence of insoluble solid phase materials. However, the volume density method can be utilized, yielding density values of 2.02 g/cm³ and 1.77 g/cm³ for the normal and foaming salts, respectively.