Preparation method of high-purity vanadium pentoxide

The invention discloses a preparation method of high-purity vanadium pentoxide, and belongs to the field of vanadium oxide preparation. The method comprises the following steps: pulping ammonium polyvanadate obtained by precipitating vanadium with acidic ammonium salt in a calcification vanadium extraction process by using water to obtain mixed slurry; heating the mixed slurry to 50-80 DEG C, and adding ammonia water to obtain an ammonium polyvanadate return solution; keeping the temperature of the ammonium polyvanadate return solution at 50-80 DEG C, adding aluminum salt or calcium salt, and stirring to react for a period of time; continuously introducing carbon dioxide gas until the pH value of the solution is 6.5-7.5, and carrying out solid-liquid separation to obtain an ammonium polyvanadate purified solution; cooling the ammonium polyvanadate purified liquid to 10-25 DEG C, crystallizing and precipitating ammonium metavanadate, and performing solid-liquid separation to obtain an ammonium metavanadate sol