Prepn of vanadium pentoxide - by precipitation of vanadic acid from ammonium vanadate with mineral acids

摘要

Vanadium pentoxide is made by pptg. vanadic acid from a mixt. of ammonium vanadate 2.0-2.5 N mineral acid at 70-95 degrees C and in which the ratio H+/VO3- = 1.0 - 1.1. The vanadic acid is filtered, pref. washed with 0.20 - 0.50% mineral acid, washed with water to pH 4-5 of washings, pre-dried at 200-300 degrees C and finally heated at 500-600 degrees C to yield V2O5 in granules of 0.5 - 20 mm. The product has high purity (99.0%) and is suitable for metallurgical operations. Ammonium vanadate is pref. made by mixing an alkali-metal vanadate with ammonium-mineral acid salt in aq. soln. at 5-25 degrees C. The mother liquor is neutralised with (NH4)2CO3 and used for further salt prepn.