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

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