Intrinsic Kinetics of Chlorination of WO3 Particles With Cl2 Gas Between 973 K and 1223 K (700 °C and 950 °C)

Abstract

Chlorination is one of the methods applied in extractive metallurgy for the treatment of mineralsto obtain valuable metals, such as titanium and zirconium. The possibility of applying chlori-nation metallurgy to other metals such as tungsten was the major aim of this study. The kineticsof the chlorination of tungsten oxide (WO3) particles has been investigated by thermogravimetrybetween 973 K and 1223 K (700 C and 950 C) and for partial pressures of chlorine rangingfrom 15 to 70 kPa. The starting temperature for the reaction ofWO3 with chlorine is determinedto be about 920 K (647 C). The influence of chlorine diffusion through the bulk gas phase andthrough the particle interstices in the overall rate was analyzed. In the absence of these twomass-transfer steps, a reaction order of 0.5 with respect to chlorine partial pressure, and anactivation energy of 183 kJ/mol were determined. For tungsten oxide particles of less than50-lm size, a complete rate expression has been obtained.