Abstract: To extract valuable vanadium element from spent vanadium electrolyte solutions, recycling and reusing technology of spent vanadium electrolyte solutions for all-vanadium redox flow battery was studied. Under the condition of normal pressure and room temperature,sodium chlorate as oxidant could be used to oxide spent vanadium electrolyte solutions deeply,and all low valence vanadium in spent vanadium electrolyte solutions was oxidized to pentavalent vanadium completely,and then ammonium metavanadate with high added value was obtained through concentration,precipitation vanadium,drying and other process. The recovery principle was analyzed. The technological conditions of recycling technology were also investigated. Results showed that the oxidation of spent vanadium electrolyte solutions with NaClO₃ is the key process for vanadium recovery rate. The best molar ratio of V⁴⁺ to NaClO₃ is 1:0.2,V³⁺ to NaClO₃ is 1:0.4. The optimum process conditions of precipitation vanadium are as follows:concentration of vanadium solution 25-30g/L,pH 8.0-8.5, precipitation temperature for vanadium 50-60℃,ammonification K 1.0-1.2,precipitation time for vanadium 80-120min. Results showed that the process has advantages of high vanadium recovery rate,low recycling cost,easy operation and environment friendly. Under the optimum process conditions,the recovery rate of vanadium is around 99%. A new route to recycle and reuse spent vanadium electrolyte of vanadium flow battery was provided.

Key words: all-vanadium redox flow battery, vanadium electrolyte solutions, recovery, precipitation vanadium, ammonium metavanadate

摘要： 为了提取失效钒电解液中有价钒元素，对全钒氧化还原液流电池失效钒电解液的回收利用进行了研究。在常温常压条件下，以氯酸钠作氧化剂对失效钒电解液进行深度氧化，使低价钒全部转变成五价钒，然后通过浓缩、沉钒、干燥等工艺过程，得到具有高附加值的偏钒酸铵。分析了回收过程的工艺原理，探讨了回收工艺的工艺条件。结果表明：NaClO₃对失效钒电解液的氧化是影响钒回收率的关键工艺过程，V⁴⁺：NaClO₃的最佳摩尔比为1：0.2，V³⁺：NaClO₃的最佳摩尔比为1：0.4；沉钒的最佳工艺条件为：钒液浓度为25～30g/L，pH为8.0～8.5，沉钒温度为50～60℃，加铵系数K为1.0～1.2，沉钒时间为80～120min。该工艺具有钒回收率高、成本低、操作简便、对环境友好等优点，在最佳工艺条件下钒的回收率可高达99%左右，为全钒液流电池失效钒电解液的回收利用提供了一条新途径。

关键词: 全钒氧化还原液流电池, 钒电解液, 回收, 沉钒, 偏钒酸铵