Measuring TiCl₄ and Vanadium in TiO₂ Pigment Production

Introduction

Known in the paint industry as the “whitest white,” titanium dioxide is a pigment used worldwide. In the chloride production method, titanium ore is converted to TiCl₄, from which metallic chloride impurities are discarded. Oxidation of purified TiCl₄ yeilds bright, finish-ready TiO₂.

There are 2 critical points of analysis in this production process:

• The incoming stream of TiCl₄ needs to be pure to yeild high quality TiO₂. This requires verification that the TiCl₄ feed is free of incident vanadium.
• The waste/recycle gas stream should be free of TiCl₄ if the process is running efficiently. The presence of TiCl₄ at this stage indicates incomplete hydrolysis and waste of valuable raw materials.

The OMA system is the ideal instrument for both analysis points, as TiCl₄ and vanadium each have distinct, strong absorbance curves in the UV wavelength range. Dispersive analysis is absolutely necessary; collateral data is needed to differentiate the absorbance of TiCl₄ from the absorbance of chlorine in the gas stream.

Absorbance Spectrum of TiCl₄ in Process Gas

The spectra below demonstrate the overlapping absorbance of the analyte (TiCl₄) and background composition (Cl₂), and the importance of a full-spectrum method. The ECLIPSE software in the OMA uses all of the measurement wavelengths (each diamond in the spectra below represents a single measurement wavelength) as data points to de-convolute the different chemicals’ absorbance curves.

Absorbance Curve of Vanadium in a TiCl₄ Background

The measurement wavelength range used for measuring vanadium concentration in this application is demonstrated below:

Sample Conditioner for Vanadium Measurement

The system below was built to measure 0-10 ppm vanadium impurity in a liquid TiCl₄ stream:

Application Data

The specifications below represent performance of the OMA-300 Process Analyzer in a typical TiCl₄ / vanadium application.

For technical details about the OMA-300 Process Analyzer, see the data sheet:
DS-001A: OMA-300 Process Analyzer

All performance specifications are subject to the assumption that the sample conditioning system and unit installation are approved by Applied Analytics. For any other arrangement, please inquire directly with Sales.

Note: Subject to modifications. Specified product characteristics and technical data do not serve as guarantee declarations.

Installation and Product Photos

Further Reading