Dissolution behavior of sodium titanates in sulfuric acid and applications to the separation of TiO 2 from titanium-containing slag

In the sodium -assisted smelting process of vanadium -titanium -magnetite (VTM), titanium oxide is hydrothermally separated by sulfuric acid solution leaching. Therefore, it is essential to study the dissolution behavior and mechanism of sodium titanates in sulfuric acid solution. High -purity Na 8 Ti 5 O 14 , Na 2 Ti 3 O 7 , and Na 2 Ti 6 O 13 samples were synthesized via solid -phase chemical reaction, and their solubilities of sodium titanates in 100 mL of 98 wt% sulfuric acid solution were determined. Na 8 Ti 5 O 14 , Na 2 Ti 3 O 7 , and Na 2 Ti 6 O 13 crystallize in the triclinic (space Group P -1), monoclinic (space Group P 2 1 / m ), and monoclinic (space Group C 2/ m ) system, respectively. The dissolution rate of sodium titanates in 98 wt% sulfuric acid solution increased significantly with rising reaction temperature. Among the sodium titanates studied, Na 8 Ti 5 O 14 showed the highest dissolution rate, followed by Na 2 Ti 3 O 7 and Na 2 Ti 6 O 13 . Kinetic analysis indicated that the dissolution behavior of sodium titanates in sulfuric acid was all governed by chemical reactions. The apparent activation energies of the dissolution reactions of Na 8 Ti 5 O 14 , Na 2 Ti 3 O 7 , and Na 2 Ti 6 O 13 with sulfuric acid were derived to be 49.48 kJ/mol, 53 kJ/mol, and 67.41 kJ/mol, respectively. The solubilities of Na 8 Ti 5 O 14 , Na 2 Ti 3 O 7 , and Na 2 Ti 6 O 13 in 100 mL of 98 wt% concentrated sulfuric acid at 20 degree celsius were determined to be 18.6077 g, 7.3297 g, and 3.9948 g, respectively. Additionally, the dissolution rates and solubilities of sodium titanates and other impurities, such as aluminate and silicate, were compared, demonstrating the effectiveness of separation in sulfuric acid solution following the sodium -assisted smelting process of VTM. In this study, it is suggested that the separation of titanium oxide from other impurities during the sulfuric acid leaching of titanium -containing slag can be accomplished based on the varying solubilities of the phases.