The chloride process of titanium dioxide (TiO2) pigment manufacture first converts titania-containing ores to TiCl4 via a carbochlorination reaction at a high temperature in a chlorinator in the presence of chlorine gas and petroleum coke added as a reductant.
In addition to the required TiCl4, other metal chlorides may be present in the condensed liquid phase crude TiCl4, dependent on the presence of these in the raw ore. Other metal chlorides include Aluminium Trichloride (AlCl3) and Vanadium Oxychloride (VOCl3). Treatment agents are typically added to the TiCl4 stream in order to complex impurity metal chlorides and separate them. VOCl3, which has the closest boiling point to TiCl4, is then typically removed by introducing a treatment agent into the process, such as oil.
The presence of VOCl3 gives the final TiO2 product a brown-tint, not ideal for a pure white product. Currently offline QC checks take place by removing a sample of the TiCl4 liquid and analysing in a lab. If impurities are found, it can be after a few hours of unsuitable product has been manufactured.
The ProtIR 304L provides a significant improvement in the QC of TiO2 production. It allows for a continuous IR measurement of the process stream, with chemometric analysis identifying and measuring the VOCl3 content in the stream in the presence of other metal oxides and dissolved gases such as COS.