石煤发电飞灰碱浸提钒工艺

Extraction of Vanadium from Fly Ash of Stone Coal Combustion by Alkaline Leaching

对我国某地石煤发电飞灰进行碱浸提钒实验研究,飞灰中的钒主要以V(V)形态弥散于硅、铝氧化物中.结合钒的赋存形式,考察了反应时间、液固比、碱浓度及温度对钒浸出率的影响.结果表明,钒浸出率与四因素均呈正比关系.在搅拌转速500 r/min、180℃、浸出时间3 h、液固比5 mL/g及NaOH浓度200 g/L的最佳工艺条件下,钒浸出率可达85%以上.浸出液中Al2O3,K,Fe含量分别小于500,420与9 mg/L.浸出液返回浸出体系,可充分利用浸出液中富余的碱进一步富集溶液中的钒.

The extraction of vanadium from fly ash of stone coal combustion in China was studied by alkaline leaching. The fly ash was characterized by a relatively high content of V5＋ in silicon and aluminum oxides. Based on the existing status of vanadium, the effects of reaction time, ratio of liquid to solid, alkaline concentration and reaction temperature on the leaching rate of vanadium were examined. The results show that the leaching rate is proportional to the four influential factors. The optimum conditions for the alkaline leaching of vanadium are stirring velocity of 500 r/min at 180℃ for 3 h, ratio of liquid to solid 5 mL/g and NaOH concentration of 200 g/L. Under the conditions, the leaching rate of vanadium reaches over 85%. The content of impurity Al2O3, K and Fe in leachate is less than 500, 420 and 9 mg/L, respectively. The leachate is recycled back to the leaching system for full use of surplus alkaline and further enrichment of vanadium in the solution.