石煤钒矿全湿法提钒技术中沉钒工艺研究

Study on Vanadium Precipitating Process of Wet Extraction Technology for Vanadium from Stone Coal

以钒反萃取液(主要成分五氧化二钒浓度99.30 g/L,铁浓度3.15 g/L)为原料,研究了钒反萃取液酸度、沉钒pH值、溶液电位等条件对沉钒率和产品五氧化二钒质量的影响。试验结果表明:针对含铁较高的上述钒反萃取液,为了获取优质五氧化二钒产品,沉钒分二段进行。第一段沉钒是先用硫酸调整钒反萃液酸度为1.5 mol/L,60℃水浴下加氯酸钠,控制溶液电位为1 000 mV,用15%的氨水调pH值在0.5以内,90℃下搅拌1 h,该段沉钒率为85%,其产品五氧化二钒含量达99%以上,铁含量在0.3%以下。第二段沉钒是将上述滤液接着用氨水调pH值至2.0并于90℃下搅拌1 h,两段总沉钒率达99%,第二段沉钒产品铁含量达1.5%,需后处理,经30%氢氧化钠溶液除铁后再次沉钒,其产品五氧化二钒含量达99%以上,铁含量在0.1%以下。

The influences of the acidity of vanadium strip liquor, pH and potential of the solution on the precipitation rate of vanadium and quality of V2O5 were investigated with the vanadium strip liquor（ V2O5 99.3 g/L and Fe 3.15 g/L） as raw material. The test results indicated that when the content of Fe was high in the strip liquor, in order to obtain high quality V2O5, precipitating vanadium was performed in two stages. In the first stage, the acidity of rich vanadium solution was adjusted to 1.5 mol/L using sulfuric acid, the potential of solution was controlled to 1 000 mV with the sodium chlorate at 60 ℃, the pH was adjusted to below 0.5 with 15% ammonia, and the solution was stirred at 90 ℃ for 1 hour. The precipitation rate of vanadium of this stage was 85%, the content of V2O5 was more than 99% and the iron content below 0.3%. In the second stage, the above filtrate was adjusted to 2.0 pH using ammonia and stirred at 90 ℃ for 1 hour. The total precipitation rate of vanadium of the two stages was above 99%. The product of the second stage contained 1.5% Fe and needed post treatment. After the Fe was removed with 30% sodium hydroxide solution, vanadium precipitating was conducted again. The contents of V2O5 and Fe in the product were more than 99% and below 0.1%, respectively.