Titanium Dioxide Manufacturing

Although titanium is a familiar construction metal in aerospace and medicine, over 90% of titanium production is used to make titanium dioxide (TiO2) for pigment in the paint, paper, plastics, and ink industries. TiO2 has replaced lead based additives in paint due to better environmental properties and a very high "hiding power" compared to alternative chemicals.

Two processes are used to produce TiO2, the sulfate process and the increasingly popular chloride process. The process used depends on the form of the titanium ore available and the desired pigment properties. Bulk minerals such as ilmenite (FeTiO3) that easily dissolve in sulfuric acid are most economically handled by the sulfate process. The chloride process is typically used on higher quality titanium ores.

Measuring pH in this manufacturing process is complicated by the very properties of the liquids used. The finely dispersed ore particles tend to badly coat standard pH sensors, first causing sluggishness and eventual total failure. This problem is compounded if the process is allowed to dry on the pH sensor. Rosemount has developed powerful solutions to preserve a viable pH measurement under these circumstances.

The first part of the solution is the high performance PERpH-X® line of pH sensors. These sensors use two layers of porous liquid junctions to separate the process chemicals from the silver reference, and allow the outer reference solution to be conveniently refilled with a preloaded syringe. The outer junction can be quickly and easily replaced to foster convenient troubleshooting. The PERpH-X reference solution can be customized for different application situations and includes a titanium solution ground for complete diagnostics of the reference and glass portions of the sensor.