Process for making titanium dioxide

An improved process for producing titanium dioxide by reacting a titanium dioxide ore with chlorine to produce a gaseous stream containing titanium tetrachloride, condensing titanium tetrachloride from the gaseous stream containing titanium tetrachioride to produce chlorinator tail gas, vaporizing the condensed titanium tetrachloride, reacting the vaporized titanium tetrachloride with oxygen to produce a gaseous stream containing titanium dioxide particles and chlorine, separating the titanium dioxide particles from the gaseous stream containing titanium dioxide particles and chlorine to produce burner tail gas, analyzing the chlorinator tail gas for residual chlorine to control the step of reacting the titanium dioxide ore with chlorine, wherein the improvement comprises the step of:

• analyzing the chlorinator tail gas for residual chlorine using an on-line chlorine analyzer wherein the chlorinator tail gas is passed through a filter and then to the on-line analyzer and wherein the chlorinator tail gas and the filter are heated to a temperature greater than fifty degrees Fahrenheit.