Analysis Of Main Impurities In Refined Titanium Tetrachloride And Process Control Research

Titanium is characterized with its low density, high strength, high heat resistance and good corrosion resistance. Thus, Titanium is now being used in many fields, such as chemical engineering, metallurgy, aviation, aerospace and pharmaceutical engineering etc. In order to remove the impurities in refined TiCl₄, there is the need to analyze the major impurities（oxygen and carbon） so that strict control can be conducted over the quality of refined TiCl₄. Up till now, according to the standard adopted by titanium factories in China, the impurities tests only include Fe Cl₃, SiCl₄,VOCl₃ together with chromaticity analysis. Due to lack of the sufficient major impurities analysis（oxygen and carbon） in refined TiCl₄, the standard adopted by the Chinese factories is rather low, which causes the low quality of titanium sponge,and Seriously influenced with the development of domestic titanium industry.This research topic is funded by National Ministry of Science and Technology Innovation Methods Special Project（No.2011IM030700）,and guided domestic titanium enterprises urgent demand of the analysis of the main impurities in refined Ti Cl₄. The research purpose is established the analysis methods of the main impurities. The research results are applied in the enterprise to control the quality of refined TiCl₄. Adopting the refined TiCl₄ produced by Zunyi Titanium Co. Ltd as the study sample, the current paper conducts examination and analysis over the major impurities（carbon and oxygen） in refined TiCl₄. The main research findings are summarized as follows:（1） Refined TiCl₄ is featured with high corrosivity. With regard to its feature in infrared spectroscopic analysis, we design a reusable infrared absorption cell device, which is leak-proof, easy to be cleaned and operated. Quantitative analysis can be used to analyze the impurities in refined TiCl₄ by adopting Infrared Spectral Method.（2）TiOCl₂ is used as the target object of infrared spectral study. Through mono-standard method, it is determined that TiOCl₂ in refined TiCl₄ is 833.8±80.0mg/kg, with RSD between 0.95%¹.94%; detection limit is 26.7mg/kg. Spiked recovery rate is between 88.5%⁹3.1%. Converting to oxygen content up to 98.8mg/kg. It can be concluded that Ti OCl₂ is the main oxygen impurity source in refined TiCl₄.（3）CO₂ is used as the target object of infrared spectral study. Through mono-standard method, it is determined that CO₂ in refined TiCl₄ is 1.53±0.11mg/kg, with RSD between 0.53%¹.27%; detection limit is 0.92mg/kg. Spiked recovery rate is 91.9 %⁹4.7%.（4）The organic impurities are used as the target object of infrared spectral study. Through mono-standard method, it is determined that the content of CS₂, CH₂ ClCOCl, CHCl₂ COCl in refined TiCl₄ is 6.6±0.1mg/kg, 17.9±0.3mg/kg, 2.2±0.4mg/kg respectively; detection limit is 0.1mg/kg, 2.0mg/kg, 1.0mg/kg respectively. The content of organic impurities are rather low and approaching the detection limit. Thus, RSD is rather big.（5）The content of organic impurities in refined TiCl₄ is rather low while the detection limit of Infrared Spectral Method is high. Thus, the content is difficult to be precisely determined. In this sense, CCl₃ COCl is used as the target research object. Through Ion Chromatography Method, it is determined that the content of CCl₃ COCl in refined TiCl₄ is 41.3mg/kg, with RSD being 7.7%; detection limit is 0.6mg/kg; spiked recovery rate is between 84.1%⁸7.3%. Converting to carbon content up to 5.4mg/kg. It can be concluded that CCl₃ COCl is a main carbon impurity source in refined TiCl₄.（6）CCl₄ is used as the target research object. Through ECD method, it is determined that the content of CCl₄ in refined TiCl₄ is 0.17mg/kg, with RSD being 2.4%; detection limit is 0.001mg/kg; spiked recovery rate is between 95%¹04%.