A Mathematic Model for Direct Causticization of Na2CO3 with TiO2 in a Semi‐batch Reactor

A mathematic model was developed for direct causticization of sodium carbonate with titanium dioxide in a semi‐batch reactor. The model predictions of the titanate yield and pentatitanate yield showed a reasonable agreement with the experimental data from a pilot‐scale fluidized bed operating in semi‐batch mode. The rate constant of the present model was generally consistent with those obtained from the small‐scale batch experiments in the literature. A new rate constant considering carbonate conversion to pentatitanate was introduced. All the results provided support that the solid‐state direct causticization of sodium carbonate with titanium dioxide in a semi‐batch fluidized bed follows the shrinking‐core diffusion model.