Study on Kinetics of Ammonium Polyvanadate Re-dissolution

Ammonium polyvanadate re-dissolution is an important process for industrial production of high purity vanadium pentoxide. The pH calibration method was employed to measure the re-dissolution rate of ammonium polyvanadate. The re-dissolution kinetics of ammonium polyvanadate was studied under production process conditions of NaOH concentration 0.5 mol/L and liquid-solid ratio 20:1. According to the kinetics experiments and calculations,the re-dissolution rate of ammonium polyvanadate was found to increase with increasing temperature and agitation speed. The kinetic model for re-dissolution of ammonium polyvanadate is unsteady-state diffusion of liquid film,with unsteady-state diffusion of liquid film as the control step and 6.15 kJ/mol of the calculated activation energy. Proper increase in agitation speed and redissolution temperature can enhance the diffusion rate for re-dissolution of ammonium polyvanadate.