Yang Fan, Peng Qiugui, Wang Jing, Xiang Lan
Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
School of Chemical Engineering & Pharmacy, Wuhan Institute of Technology, Wuhan 430205, China.
Nanomaterials (Basel). 2023 Dec 20;14(1):12. doi: 10.3390/nano14010012.
Ti-bearing blast furnace slag (TBFS) can be converted to impurity bearing TiOSO solution for TiO pigment production. However, the HTiO (MTA) hydrolyzed from the solution has too high Fe/V impurity to meet the standard for TiO pigment. In this study, we found that Fe and V were easily hydrolyzed and entered the MTA lattice, and hence could not be removed by washing. Furthermore, Fe/V was hard to co-remove by the traditional reduction method. Therefore, the Fe/V non-hydrolysis condition (Ti = 0.01 M, = 3.0, T = 130 °C; Ti = 0.01 M, = 3.5, T = 150 °C) was determined by thermodynamic calculations. However, at these conditions, the Ti hydrolysis ratio was low or the reaction time was long. Therefore, a new two-step hydrothermal hydrolysis process was proposed. Step 1 (130 °C, 2 h) ensured the non-hydrolysis of V, and Ti was partially hydrolyzed to increase the HSO concentration. Step 2 (150 °C, 2 h) ensured a high Ti hydrolysis ratio (>0.95) and short total reaction time (4-6 h). Finally, a high-purity MTA was obtained (Fe = 21 ppm, V = 145 ppm). These results provide new insights into the control of the hydrolysis of impurity ions in solutions and help to optimize the process of TiO pigment preparation from TBFS.
含钛高炉矿渣（TBFS）可转化为含杂质的硫酸氧钛溶液用于生产钛白粉。然而，从该溶液中水解得到的偏钛酸（MTA）铁/钒杂质含量过高，无法满足钛白粉的标准。在本研究中，我们发现铁和钒很容易水解并进入MTA晶格，因此无法通过洗涤去除。此外，铁/钒难以通过传统的还原方法共同去除。因此，通过热力学计算确定了铁/钒不水解条件（Ti = 0.01 M， = 3.0，T = 130 °C；Ti = 0.01 M， = 3.5，T = 150 °C）。然而，在这些条件下，钛的水解率较低或反应时间较长。因此，提出了一种新的两步水热水解工艺。步骤1（130 °C，2 h）确保钒不水解，钛部分水解以提高硫酸浓度。步骤2（150 °C，2 h）确保高钛水解率（>0.95）和较短的总反应时间（4 - 6 h）。最终，获得了高纯度的MTA（Fe = 21 ppm，V = 145 ppm）。这些结果为控制溶液中杂质离子的水解提供了新的见解，并有助于优化从TBFS制备钛白粉的工艺。
