多钒酸铵返溶的动力学研究

Study on Kinetics of Ammonium Polyvanadate Re-dissolution

多钒酸铵返溶是工业上生产高纯五氧化二钒的重要步骤。采用p H标定法测量多钒酸铵的返溶率,在氢氧化钠浓度为0.5 mol/L,液固比为20∶1的现行生产工艺条件下对多钒酸铵返溶的动力学进行了研究。结果表明:多钒酸铵的返溶率随温度和搅拌速度的增大而增大;多钒酸铵返溶的动力学模型为液膜非稳态扩散模型,受液膜非稳态扩散控制,表观活化能为6.15 k J/mol;适当增大搅拌速度、升高返溶温度都能提高多钒酸铵返溶的扩散速率。

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 produc- tion process conditions of NaOH concentration 0.5 mol/L and liquid-solid ratio 20 ： 1. According to the ki- netics experiments and calculations, the re-dissolution rate of ammonium polyvanadate was found to in- crease 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 re- dissolution temperature can enhance the diffusion rate for re-dissolution of ammonium Dolyvanadate.