回用盐对铝粉除钒精制四氯化钛质量的影响研究

Study on the effect of recycled salt on the quality of vanadium removal and refining titanium tetrachloride from aluminum powder

通过处理熔盐氯化生产四氯化钛过程中产生的盐酸和废盐水,获得含NaCl的回用盐。采用ICP、红外光谱和XRD的检测方法分析发现:回用盐中除了含有NaCl外还含有Na_(2)SO_(4)、NaClO_(3)和Na_(2)S_(2)O_(4)等杂质成分。通过热力学计算表明,在700~800℃的氯化温度条件下,Na_(2)SO_(4)在与氯气加碳氯化的条件下可能生成SO_(2)、SO_(2)Cl_(2)、SOCl_(2)、SCl_(2)、S_(2)Cl_(2)和CS_(2)等多种硫化物,其中溶于粗四氯化钛中的SO_(2)Cl_(2)、SOCl_(2)和SCl_(2)在蒸馏釜内会与铝粉除钒试剂中的TiCl_(3)参与反应,容易造成蒸馏液中的VOCl_(3)和AlCl_(3)含量超标,导致铝粉单耗增高,钛收率降低,精四氯化钛产品质量下降,回用盐不适合用于熔盐氯化生产四氯化钛。

The recycled salt containing NaCl was obtained by treating the hydrochloric acid and waste brine produced in the chlorination process of molten salt to produce titanium tetrachloride.By means of ICP,IR and XRD,it is found that the recycled salt contains impurities such as Na_(2)SO_(4),NaClO_(3) and Na_(2)S_(2)O_(4) in addition to NaCl.The thermodynamic calculation shows that at the chlorination temperature of 700~800℃and under the carbochlorination condition,Na_(2)SO_(4) may form many kinds of sulfides such as SO_(2),SO_(2)Cl_(2),SOCl_(2),SCl_(2),S_(2)Cl_(2),CS_(2) and so on.SO_(2)Cl_(2),SOCl_(2) and SCl_(2) dissolved in crude titanium tetrachloride will react with TiCl_(3) in the vanadium removal reagent of aluminum powder in the distillation kettle,which can easily lead to excessive content of VOCl 3 and AlCl_(3) in the distillate,resulting in an increase in the unit consumption of aluminum powder and a decrease in titanium yield.The quality of refined titanium tetrachloride products is declining,and the recycled salt is not suitable for molten salt chlorination to produce titanium tetrachloride.