Research on Precipitation Process and Dynamics Behaviors of Ammonium Polyvanadate

The precipitation process of ammonium polyvanadate was studied in this paper.At the optimum conditions of 32～40 g/L for vanadium concentration in the solution by roasting-leaching process,0.8～1.2 of precipitant addition coefficient,above 65 ℃ of temperature before the acid addition,1.7～2.1 of precipitation pH and about 93 ℃ of boiling temperature for 52～60 min,a precipitation rate of vanadium over 99% can be achieved.Furthermore,the kinetics behaviors for precipitation of ammonium polyvanadate were investigated at the optimum conditions.The precipitation process of ammonium polyvanadate can be described by Avrami crystallization kinetics equation,with the apparent activation energy E_a=35.87 kJ/mol and the pre-exponential factor A=5.42×10²⁰ min^-1,respectively.