In this work it is tried to develop a mathematical model for fluidized bed carbochlorination zircon and zirconia reactors. Therefore a computer program with MATLAB is written for each reactor. After literature survey, all needed data, such as reaction rate and stoichiometry, feeds of reactors etc. are determined. The two-phase hydrodynamic model type is used to describe the bed behavior. Mass balance of chlorine on each phase is written by assuming plug flow of gas in bubble phase and plug flow or mixed flow (two cases) of gas in dense phase. Population balance is written to find the size distribution of solids in bed. To formulate energy balance, isotherm condition is considered. Fourth-order Rung-Kutta method were applied to solve equations. Error analysis on model predictions shows a better results of model which assumes mixed flow on dense phase. By using these model, effects of reactor temperature, inlet gas velocity and concentration and size distribution of inlet solids on chlorine conversion and converted solids were investigated and optimum conditions were determined.