高浓度盐酸体系下叔胺N235三相萃取钒试验

摘要

含钒石煤经盐酸浸出后所得浸出液通常酸度较高,pH较低.为在不调节浸出液pH的条件下,以叔胺N235为萃取剂从高浓度盐酸—钒体系中萃取钒的最佳工艺,考察了萃取剂的组成、萃原液盐酸浓度、萃取相比(O/A)、萃取时间对钒萃取率的影响,并通过FT-IR分析探讨了在不同盐酸浓度下N235萃取钒形成的萃合物结构.试验结果表明:对盐酸浓度为2 mol/L,钒浓度为1.82 g/L的模拟酸浸液,在有机相N235体积浓度为20%,萃取时间为2 min,萃取温度为25℃,相比(O/A)为0.5情况下的钒单级萃取率为83.93%,三级逆流萃取钒总萃取率为98.37%.利用叔胺N235从盐酸介质中萃取钒时,均会出现三相.在萃原液盐酸浓度≥3.1 mol/L时,萃合物结构为(R3NH)4·(H2O)n·H2V10O28·(HCl)x;萃原液盐酸浓度<3.1 mol/L时,萃合物结构为(R3NH)4·(H2O)n·H2V10O28.%The stone coal acidic leaching solution after hydrochloric acid leaching process usuallyhas high acidity and pH is relatively low. For investigating the best extraction parameters of vanadium( V) from the high concentration of hydrochloric acid/vanadium system with tertiary amine N235 as extractant without adjusting the acidic leaching solution pH,three-phase ex-traction process was studied,the effects of the extractant composition,HCl concentration in feed,extraction phase O/A ratio and extraction time on vanadium extraction efficiency were studied,and the structure of extracted complex in the process of recove-ring vanadium with N235 in different hydrochloric acid concentrations was analyzed with FT-IR. The results showed that V ex-traction efficiency after one-stage extraction was 83. 93% under the optimum condition of HCl concentration in feed of 2 mol/L,feed simulation solution containing 1. 82 g/L vanadium(V)organic phase N235 concentration in volume is 20%,ex-traction temperature is 25 ℃,O/A phase ratio of 0. 5,and extraction duration of 2 min,extraction efficiency for three-stage counter-current extraction was 98. 37%. Meanwhile,when tertiary amine N235 was used to recover vanadium from hydrochloric acid medium,the three-phase was always formed. When hydrochloric acid concentration in feed was more than 3. 1 mol/L, structure of extracted complex was (R3NH)4·(H2O)n·H2V10O28·(HCl)x,otherwise,the structure of extracted complex was ( R3 NH) 4 ·( H2 O) n ·H2 V10 O28 .