Recent advances in China’s titanium production industry

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Our country is extremely rich in titanium resources, accounting for about 48% of the world’s total reserves, ranking first in the world. Vanadium-titanium magnetite in the Panxi region accounts for 90.5% of China’s titanium resources. However, due to its low grade, high calcium and magnesium content, and difficulties in processing, the utilization rate of titanium is only 4.9%. A large amount of unutilized tailings and blast furnace slag are discharged into the environment, causing severe environmental pollution in the Jinsha River basin upstream of the Yangtze River. The traditional sulfuric acid process for titanium dioxide production features a long production cycle and complex procedures. For every ton of titanium dioxide produced, approximately 7–11 tons of waste sulfuric acid and 0.2–0.3 tons of waste residue are generated, resulting in severe environmental pollution and posing a bottleneck to the development of China’s titanium dioxide industry. A research team led by Academician Zhang Yi from the Institute of Process Engineering, Chinese Academy of Sciences, proposed for the first time a new titanium purification metallurgy process using the sub-molten salt method. This process utilizes alkali metal hydroxides in a sub-molten state as the reaction medium; it is completely different from the traditional sulfuric acid and chlorination methods. It enables the efficient and selective conversion of titanium in ilmenite or high-titanium slag into titanate intermediates at normal pressure and lower temperatures. Inert elements such as Ca, Mg, and Fe do not react with titanates and remain in the slag phase, thereby allowing for the separation of titanium from Ca, Mg, and Fe. The separated iron slag can be further utilized. Building on this foundation, Researcher Qi Tao and his colleagues proposed an optimized process for treating high-titanium slag to produce titanium dioxide with low alkali consumption and low costs. For the first time, high-titanium slag was used as a raw material; the KOH sub-melting salt method was employed to prepare potassium trititanate intermediates, which were then hydrolyzed to yield potassium octatitanate whiskers of high added value, or to produce titanium dioxide directly. This approach opened up new pathways for the production of titanium dioxide and potassium titanate whiskers. This new process has advantages such as simple operation, short process flow, potassium regeneration cycle, and good economic efficiency, offering broad application prospects. A new method for the clean preparation of titanium-containing products such as titanium dioxide by treating ilmenite or high-titanium slag with NaOH (or KOH) in a sub-molten salt system is expected to see further expansion of experiments in the coming years. This approach aims to further refine the technology that combines electrochemical methods with the comprehensive utilization of mineral resources for processing titanium slag, while gradually increasing the scale of these experiments. On this basis, it is expected that clean treatment technologies for various other metal minerals can be developed and promoted. In addition, research on new metallurgical processes and technologies will also focus on using electrolysis to replace high-temperature reduction-oxidation smelting methods for the production of certain rare metals such as Nb and Ta, and practical applications will be achieved. In recent years, Zhu Hongmin and others have proposed a method of combining carbothermal reduction with molten salt electrolysis to obtain metallic titanium from high-titanium slag, and have achieved promising results in using this approach to produce metallic titanium and titanium alloys from the high-titanium slag produced by China’s Panzhihua Iron and Steel Company ； Guo Zhancheng and others also achieved success in studying a method for directly preparing TiFe alloys through electrolysis using TiO2 and Fe2O3. In short, cleaner production, which prevents pollution at the source of production, is an important strategy for protecting the environment and achieving sustainable development. The establishment of a new system for clean production requires breaking away from the traditional production methods that have been in use for a long time, in order to achieve technological upgrades in industries traditionally associated with pollution from a high starting point. Chinese scientists have achieved significant results in the use of new metallurgical processes and technologies for the production of chromium, titanium, and rare metals such as Nb and Ta. These efforts have led to a marked reduction in environmental pollution and energy consumption during the production process, which in turn gave rise to the concept of green chemistry.