Na_2CO_3高压浸出SCR脱硝废催化剂中的钨和钒

High Pressure Leaching of Tungsten and Vanadium with Sodium Carbonate from Spent SCR Denitration Catalyst

采用Na_2CO_3高压浸出工艺回收SCR脱硝废催化剂中的钨和钒,考察了焙烧预处理温度、浸出添加剂种类及用量、Na_2CO_3用量、液固比、浸出时间和浸出温度对钨和钒浸出效果的影响,并通过XRD表征对SCR脱硝废催化剂浸出前后的物相结构变化进行了分析。结果表明,SCR脱硝废催化剂无需经过焙烧预处理即可进行浸出,具体优化实验条件为:Na_2CO_3加入量20%、NaOH加入量8%、液固比2∶1、浸出时间2h和浸出温度230℃,在此条件下钨浸出率为75.06%,钒浸出率为89.35%。XRD分析结果显示,SCR脱硝废催化剂中的钛主要以锐钛型TiO_2形式存在,高温焙烧促使TiO_2由锐钛型向金红石型转变,不利于钨和钒的浸出;部分钨可能以固溶体形式存在于TiO_2中,为提高钨浸出率,需强化浸出条件以破坏TiO_2的结构。

Tungsten and vanadium were recovered from spent SCR denitration catalyst by high pressure leaching with Na2CO3.The effects were investigated of roasting pretreatment temperature,type and dosage of the leaching additive,Na_2CO_3 dosage,liquid-solid ratio,leaching time and temperature for tungsten and vanadium leaching.The phases of spent SCR denitration catalyst were analyzed by XRD characterization before and after leaching.The results show that spent SCR denitration catalyst can be leached without roasting pretreatment,and the optimized experimental conditions are as follows:Na_2CO_3addition of 20%,NaOH addition of 8%,liquid-solid ratio of 2∶1,leaching time of 2hand leaching temperature of 230 ℃.Under the above conditions,the leaching rates of tungsten and vanadium reach 75.06% and 89.35%,respectively.In addition,the XRD analysis results show that titanium exists mainly in the form of anatase TiO_2 in spent SCR denitration catalyst,and high-temperature roasting can promote TiO_2 transition from anatase to rutile,inhibiting tungsten and vanadium leaching.Part of tungsten may exist in TiO_2 in the form of solid solution,and therefore the microstructure of TiO_2 should be destroyed by strengthening leaching conditions to further improve the leaching rate of tungsten.