© 2014, Chemical Publishing Co. All rights reserved.This study, examined the calcination of phosphate rock in fluidized bed, the effects of gas flow rate, temperature, particle size, calcination time and the rate of CO2 on the decomposition rate. Calcination rate was observed to increase with increasing gas flow rate and temperature, but decreased with increasing particle size and CO2 ratio in the fluid gas medium. Moreover, phosphate rock calcination was detected to conform to the unreacted core model among the heterogeneous reaction models. Both the fact that particle size is much more effective and the results of the Arrhenius equality support the transfer mechanism from ash film. In addition, the fact that the flow rate of the gas is very much effective suggests that the controlled transfer mechanism from fluid film affects the calcination as well. However, it can be proposed that the step which determines the velocity of the calcination reaction is the mass transfer controlled mechanism of CO2 in the ash film with 31.08 kJ/mol activation energy.