一步法石煤提钒反萃液酸性铵盐沉钒试验研究

Vanadium Precipitation with Acidic Ammonium Salt of Stripping Solution from One-Step Vanadium Extraction of Stone Coal

以一步法石煤提钒反萃液为研究对象,研究了最佳的沉钒初始条件以及沉钒时间、温度、p H、搅拌强度等对沉钒率和产物多聚钒酸铵（APV）质量的影响。为了解决酸性铵盐沉钒过程废水中NH＋4过量的问题,需要使NH＋4浓度尽可能的低,根据反萃液钒浓度、反萃液初始p H值和氨水用量三者之间的平衡关系,通过计算验证,确定沉钒的最佳初始条件是：反萃剂为8%H2SO4,反萃液钒浓度为19.91 g·L-1,反萃液初始p H=-0.18。酸性铵盐沉钒条件研究结果表明：沉钒p H值不同,沉淀产物APV的晶体类型也会存在差异,在p H=1.7~2.1和2.2~5.0的条件下,APV主要成分分别为NH4V3O8·0.5H2O和（NH4）2V6O16·1.5H2O;沉钒温度在20~50℃时,沉淀产物主要是Na V3O8·x H2O,多聚钒酸铵的沉淀反应并没有发生,温度〉50℃之后,沉钒产物才逐渐向NH4V3O8·0.5H2O转化;在最佳沉钒工艺：时间1 h、温度70~100℃、p H=1.9~2.0、搅拌强度400 r·min-1的条件下,沉钒率〉99%,APV纯度〉98%。

Using stripping solution from vanadium extraction with one-step method as raw material, the best initial condition of vana- dium precipitation with acidic ammonium salt was confirmed. Meanwhile, the factors including time, temperature, pH of vanadium precipitation and stirring intensity that contributed to vanadium precipitation rate and ammonium polyvanadate （APV） purity were dis- cussed. In order to solve the problem of excessive NH; in waste water during vanadium precipitation and make the concentration of NH4 as low as possible, a balance among vanadium concentration, initial pH of stripping solution and amount of ammonia was calculated and verified. With 8% HESO4 as stripping agent, the vanadium concentration and pH were determined to be 19.91 g·L-1, -0.18, re- spectively. Some changes of APV crystal form were discovered at different pH values. When pH was 1.7 - 2.1, the main component of APV was NH4V3O8·0.5H20, while its main existence was （NH4）2V6016·1.5H20 with pH of 2.2 - 5.0. When the temperature of vanadium precipitation was between 20 and 50 ℃ , the precipitation was not ammonium polyvanadate but NaV3 08·xH2 O, and APV pre- cipitation reaction never occurred. With temperature of above 50 ℃, the main precipitation became NH4V3O8·0.5H20. The vanadium precipitation rate could be as high as 99%, and ammonium polyvanadate purity could also be about 98% under the optimized condition： precipitation time of 1 h, temperature of 70 -100 ℃, vanadium precipitation pH of 1.9 - 2.0 and stirring intensity of 400 r.min-l.