摘要
本文提出利用D2EHPA(P204)、磷酸三丁酯(TBP)和氯化钠(NaCl)从赤泥酸浸液中选择性萃取钪的方法。研究了P204浓度(XP204)、氯化钠浓度(C_(NaCl))、pH值、反应时间、搅拌速度和O/A等参数对酸浸液中钪萃取与铁分离效果的影响。利用傅立叶变换红外光谱(FT-IR)和萃取热力学理论阐述了浸出液中钪的萃取机理,通过溶液热力学理论解释抑制铁萃取的作用机制。结果表明:在溶液pH值为1.2、搅拌速度为200 r/min、反应时间为6 min、C_(NaCl)为75 g/L、X_(P204)为0.75的条件下,钪、铁的单级萃取率和β(Sc/Fe)分别为99.1%、9.4%和1061.2,钪与铁的分离效果较好。Sc─O振动吸收峰的形成有利于P204萃取赤泥酸浸液中的钪。通过向赤泥浸出液中添加NaCl,溶液中铁离子会形成[FeCln]^(3−n)络合物,增加氯离子浓度,络合物中n值升高,[FeCln]^(3−n)的价态降低,从而抑制了P204萃取浸出液中的铁。依据McCabe-Thiele图谱进行了三级逆流萃取实验,该反应的吉布斯自由能变为−5.93 kJ/mol,焓变为23.45 kJ/mol,熵变为98.54 J/(mol·K),表明该过程可自发进行且为吸热反应,适当增加反应温度有利于钪的萃取回收。
D2EHPA(P204),tri-butyl-phosphate(TBP)and sodium chloride(NaCl)were attractive for selective extraction of scandium from acid leaching solution of red mud.The extraction parameters of P204 concentration(X_(P204)),NaCl concentration(C_(NaCl)),pH value,reaction time,stirring speed and O/A were investigated to extract scandium and separate iron from the acid leaching solution.The extraction mechanism was analyzed by Fourier transform infrared spectroscopy(FT-IR)and thermodynamic theory.The single-stage extraction efficiency of scandium,iron andβ(Sc/Fe)were 99.1%,9.4%and 1061.2,respectively,with C_(NaCl) of 75 g/L and XP204 of 0.75 at solution pH value of 1.2 and stirring speed of 200 r/min for 6 min,in which a good separation effect of scandium and iron was obtained.The vibration absorption peak Sc─O was contributed to the extraction of scandium with P204.The complex[FeCln]^(3−n) existed in the solution with adding NaCl into the acid leaching solution.The value of n was higher and the valence state of the complex[FeCln]^(3−n) was lower with an increase of chloride concentration,which restricts the extraction efficiency of iron with P204.The extraction of three stages in the counter-current simulation experiments was carried out according to the McCabe-Thiele diagram.Gibbs free energy change(ΔG)of−5.93 kJ/mol,enthalpy change(ΔH)of 23.45 kJ/mol and entropy change(ΔH)of 98.54 J/(mol·K)were obtained in the solvent extraction proces,which indicate that the extraction reaction is easily spontaneous and endothermic and a proper increase of temperature is conducive to the extraction of scandium.
作者
李望
刘月
朱晓波
LIWang;LIU Yue;ZHU Xiao-bo(School of Chemistry and Chemical Engineering,Henan Polytechnic University,Jiaozuo 454000,China;State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control,Wuhan University of Science and Technology,Wuhan 430081,China;Collaborative innovation center of coal mine safety of Henan Province,Henan Polytechnic University,Jiaozuo 454000,China)
基金
Projects(51904097,51804103)supported by the National Natural Science Foundation of China
Project(2019GGJS056)supported by the Training Program for Young Backbone Teachers in Colleges and Universities of Henan Province,China
Project(HB201905)supported by Open Foundation of State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control,China
Project(202102310548)supported by Scientific and Technological Project of Henan Province,China
Project(21IRTSTHN006)supported by Program for Innovative Research Team in the University of Henan Province,China。
关键词
钪
选择性萃取
D2EHPA/氯化钠
浸出液
赤泥
scandium
selective extraction
D2EHPA/sodium chloride
leaching solution
red mud