陕西某石煤钒矿酸浸液中钒与铁的分离研究

Study on Separation of Vanadium and Impurities from Acid Leach Supernatant of Vanadium-containing Stone Coal

以陕西某石煤酸浸含钒上清液为原料,先用石灰乳中和、硫代硫酸钠还原预处理,采用P204+TBP+磺化煤油萃取体系萃取富集、纯化五氧化二钒浸出液;采用不同酸度硫酸作反萃剂,对负载有机相反萃取,进行钒、铁分离。结果表明:浸出液经石灰乳中和,硫代硫酸钠还原,控制溶液pH=2.5,溶液电位为-200 mV,当A/O=2,经6级逆流萃取,钒的萃取率达99%以上,而铁萃取率仅为11%;反萃剂酸度控制在1.0～1.25 mol/L,O/A=18,经5级逆流反萃取,钒的反萃取率可达99%以上,铁的反萃取率仅为9%。反萃取水相中V2O5浓度为75.3 g/L,Fe浓度为1.2 g/L,反萃水相中钒铁质量比为62.8,钒铁分离效果较好,满足后续提钒要求。

The vanadium-containing supernatant, after acid leaching of some stone coal from Shaanxi Province, was firstly pretreated by being neutralized with lime milk and reduced with sodium thiosulfate. Then, a combination of P204 ＋ TBP ＋ sulfonated kerosene was used for extraction and concentration, obtaining leach liquor of vanadium pentoxide. At last, sulfuric acid with different acidity was used as stripping agent in back-extraction of load organic phase for separation between vanadium and iron. Tests results showed that after the supernatant was pretreated by neutralization with lime milk and reduction with sodium thiosulfate, the solution was controlled at a pH of 2.5, with an electric potential of -200 mV. After six-stage countercurrent extraction at A/O = 2, the vanadium extraction rate was more than 99% while the iron extraction rate only 11%. When the acidity of stripping agent was controlled within 1.0 ~ 1.25 mol/L, 5-stage countercurrent back-extraction at O/A = 18 resulted in back-extraction rate of over 99% and 9% for vanadium and iron, respectively. The concentration of V205 and Fe in the liquid phase after back-extraction is 75.3 g/L and 1.2 g/L, respectively, with the mass ratio of vanadium to iron being 62.8, which can meet the requirement for the follow-up process.