Chemical removal of vanadium impurities in titanium tubes!

Release time：2022-11-08 17:59:28 丨 Number of visits：

The vanadium impurities in the titanium tube are mainly VOCl3 and a small amount of VCI4. Their presence makes the TC4 titanium alloy tube yellow. The purpose of vanadium removal is not only to decolorize, but also to deoxygenate. This is a very important part of the refining process.

The boiling point difference and relative volatility of the titanium tube and vanadium impurities are relatively small. For example, the boiling point difference between the two components of the titanium-Vocl3 system is 10℃, and the relative volatility d = 1.22. The difference of boiling point between TC4 titanium alloy tube and VCl4 series is 14 degrees Celsius. In theory, however, it is possible to remove vanadium impurities by physical methods, such as high efficiency rectification towers. The advantages of this method are that chemical reagents are not needed, the refining process is continuous production, easy to realize automation, and the separated VOCl3 and VCl4 can be used directly. The disadvantage is that the energy consumption is large, the equipment investment is large, and the structure of the high-power kettle needs to be solved, so it has not been used in industry.

In addition, TC4 titanium alloy tube -- V0Cl3 system two components of the freezing point difference is large, about 54 degrees Celsius difference, so it can also be used to remove VOCI3 cryo-crystallization method, but the freezing energy consumption is large, so it has not been used in industrial applications.

For this reason, vanadium is often removed by chemical method. Chemical removal of vanadium is to add a chemical reagent in the titanium tube, so that VOCl3(or VCl4) impurities selective reduction or selective precipitation generated insoluble alum compounds and TC4 titanium alloy tube separation or selective adsorption of VoCl3(or VCl4), so that vanadium impurities and TC4 titanium alloy tube separation; Or selectively dissolved VOCl2, so that the alum impurities and 7icld separated from each other. It can be said that a more ideal technology of vanadium removal, which is simple in process equipment, low in cost, good in working conditions and easy to realize continuous operation, has not been established. This is also the TC4 titanium alloy tube refining process needs to be studied.