【作者】 刘红；

【导师】 张一敏；

【作者基本信息】 武汉科技大学 ， 矿业工程， 2019， 博士

【摘要】 从含钒页岩中提取钒已经成为一种获取钒的重要途径。为了提高钒总回收率,工业中普遍采用的硫酸浸出工序常采取高酸、高温以及加入助浸剂等措施,导致浸出过程钒选择性不高。在钒溶出的同时也伴随着云母中其他杂质元素以及脉石矿物元素的溶解,给后续净化富集工序带来了很大的难度。本研究针对钒页岩浸出液“高酸、多杂”的特点,提出了混合载体液膜提钒工艺,以达到缩短工艺流程、提高萃取效率的目的,同时对液膜中钒的传质机理以及协同萃取的机理进行深入分析,主要研究内容和结论如下:（1）钒页岩提钒酸浸液的溶液化学研究确定了四价钒离子、五价钒离子、硫酸根、氟离子、磷的含氧酸根离子、铝离子、铁离子、钾离子、钠离子和镁离子在页岩酸浸液中的分布规律,对特定离子在不同pH值下的不同存在形式进行了定量计算,并根据杂质离子与钒离子性质的差异为后续净化富集机制的选择提供指导。（2）D2EHPA乳化液膜萃取页岩钒酸浸液工艺及传质机理D2EHPA作为乳化液膜体系的载体效果优于PC88A、Cyanex272以及N235。考查了制乳转速、制乳时间、D2EHPA浓度、span80浓度、石蜡浓度、反萃剂硫酸浓度、相比（O/A）、温度、电破乳对液膜稳定性及萃取效率的影响;并考查了液膜萃取过程中钒的迁移规律以及钒与杂质离子的分离机制,根据不同杂质离子的影响大小设计了D2EHPA乳化液膜萃取实际页岩提钒酸浸液的分离流程,在最佳条件下萃取率达到97.2%,此时,杂质离子的萃取率分别为Fe 8.5%,Al 11.1%,Mg 2.8%,K 1.5%,Na 1.9%;建立动力学模型描述钒的迁移过程,并对相关动力学参数进行了计算。（3）N235支撑液膜萃取页岩钒酸浸液工艺及传质机理N235作为支撑液膜的载体效果优于D2EHPA、PC88A以及Cyanex272。对支撑液膜的最佳制备及萃取条件（N235浓度、溶液pH值、反萃剂种类及浓度、稀释剂种类）进行了考查,在最佳条件下传质时间13 h时,钒的萃取率可达92.0%;并对N235支撑液膜体系杂质离子的影响机制及分离流程进行研究,表明P、Fe、Al是主要影响杂质元素,这是由于这三种离子均存在可被N235萃取的阴离子形式,在一定范围内浓度的升高对钒的萃取产生了竞争效果导致钒萃取率降低,而Mg、K、Na浓度的升高并不影响钒的萃取;建立了一级传质动力学模型,模型计算结果与试验结果较为一致,并得到相关传质动力学参数。（4）Cyanex272-N235混合载体支撑液膜萃取钒页岩酸浸液工艺及高纯钒制备Cyanex272-N235混合载体作为支撑液膜载体效果优于试验中采用的单一萃取剂。对支撑液膜的最佳制备及萃取条件（萃取剂配比、溶液pH值、反萃剂种类及浓度）进行了考查,在最佳条件下传质时间13 h时,钒的萃取率可达97.2%;并对该混合载体支撑液膜体系杂质离子的影响机制及分离流程进行研究,表明P、Fe、Al是主要影响杂质元素,在一定范围内浓度的升高对钒的萃取产生了竞争效果导致钒萃取率降低,而Mg、K、Na浓度的升高并不影响钒的萃取;对该萃取体系的循环性能进行考查,并对得到的富钒液进行了弱碱性铵盐试验,可得到纯度99.31%的V₂O₅产品。（5）基于DFT理论的混合载体液膜强化钒萃取机理研究N235质子化的过程实质是H质子与N原子HOMO孤对电子成键的过程;Cyanex272易自发形成二聚体和三聚体,二聚体的氢键形成过程中,P=O键O的HOMO电子向O-H键H的LUMO偏移,使O-H键H周围电子能量升高,三聚体的形成削弱了P=O键O原子附近的高能电子轨道,使该位点发生电子转移的能力降低;N235与Cyane272混合体系强化钒萃取的实质是质子化N235的N-H与Cyane272单体的O-H争夺P=O键形成氢键的过程,对此过程进行能量分析可知该络合反应可自发形成,P=O···H-N键的形成伴随着二聚体的解离以及自由Cyanex272的释放,同时络合体中Cyanex272的O-H键极性增强,H⁺更易电离,进而更易与VO₂⁺进行交换反应,另外,该混合萃取体系具备对阴离子形态和阳离子形态钒离子均可萃取,也提高了对酸浸液中钒离子的萃取能力。更多还原

【Abstract】 Extraction of vanadium from vanadium-bearing shale has become one of the most important method to obtain vanadium-containing products.In order to improve the total recovery rate of vanadium,the sulfuric acid leaching process is commonly used in industry with high acid,high temperature and the addition of dipping agent,resulting in low selectivity of the leaching process.The dissolution of vanadium in mica is accompanied by the dissolution of other impurity elements in mica and gangue mineral elements,which brings great difficulty to the subsequent purification and enrichment process.In this study.a vanadium extraction process is proposed to improve the process flow and extraction efficiency.At the same time,the mass transfer mechanism of vanadium in the liquid film and the mechanism of synergistic extraction is analyzed in depth.The main research contents and conclusions are as follows:(1)Solution chemistry study of vanadium shale vanadate acid leaching solutionThe distribution of tetravalent vanadium ions,pentavalent vanadium ions,sulfates,fluoride ions,phosphorus oxyacid ions,aluminum ions,iron ions,potassium ions,sodium ions and magnesium ions in shale acid leaching solution was determined.Quantitative calculations were carried out for the different forms of specific ions at different pH values,and guidance was provided for the selection of subsequent purification and enrichment mechanisms based on the difference in the properties of impurity ions and vanadium ions.(2)D2EHPA emulsion liquid membrane extraction shale vanadium leaching process and mass transfer mechanismD2EHPA is superior to PC88A,Cyanex272 and N235 as the carrier of emulsion liquid membrane system.The effects of emulsification speed,emulsification time,D2EHPA concentration,span80 concentration,paraffin concentration,stripping agent sulfuric acid concentration,phase ratio(O/A),temperature,electric demulsification on liquid film stability and extraction efficiency were investigated.The migration of vanadium during the extraction of liquid membrane and the separation mechanism of vanadium and impurity ions were investigated.The separation process of the actual shale vanadium leaching solution was designed based on the influence of impurity ions on the D2EHPA carrier emulsion liquid membrane.The rate reached 97.2%.At this time,the extraction rates of impurity ions were Fe 8.5%,Al 11.1%,Mg 2.8%,K1.5%,and Na 1.9%.The kinetic model was established to describe the migration process of vanadium and related kinetics,and the parameters were calculated.(3)N235 supported liquid membrane extraction shale vanadium leaching process and mass transfer mechanismN235 is superior to D2EHPA,PC88A and Cyanex272 as a carrier in supporting liquid membrane.The optimal preparation and extraction conditions(N235concentration,solution pH value,stripping agent type and concentration,diluent type)of the supported liquid membrane were investigated.Under optimal conditions,the extraction rate of vanadium was 92.0%;The mechanism and separation process of the impurity ions of N235 supported liquid membrane system were studied,indicating that P,Fe and Al are mainly affecting impurity elements,because these three ions have an anion form which can be extracted by N235 The increase of concentration in a certain range has a competitive effect on the extraction of vanadium,which leads to the decrease of vanadium extraction rate,while the increase of Mg,K and Na concentration does not affect the extraction of vanadium;a first-order mass transfer kinetic model is established.The calculated results of the model are consistent with the experimental results,and the relevant mass transfer kinetic parameters are obtained.(4)Cyanex272-N235 mixed carrier supported liquid membrane extraction shale vanadium leaching process and the preparation of high purity of vanadium products.The Cyanex272-N235 mixed carrier is superior to the other single extractants used in this study as a supporting liquid membrane carrier.The optimum preparation and extraction conditions(extractant ratio,solution pH value,stripping agent type and concentration)of the supported liquid membrane were investigated.Under the optimal conditions,the extraction rate of vanadium reached 97.2%at 13h.;And the mechanism and separation process of the impurity ions of the mixed carrier supported liquid membrane are studied,P,Fe and Al mainly affect the impurity elements,and the concentration increase in a certain range has a competitive effect on the extraction of vanadium.The extraction rate of vanadium is reduced,and the increase of Mg,K and Na concentration does not affect the extraction of vanadium;the cycle performance of the extraction system is investigated,and the obtained vanadium-rich liquid is tested by weak alkaline ammonium salt.A V2O5 product with a purity of99.31%was obtained.(5)Mechanism of enhanced vanadium extraction by mixed carrier liquid membrane based on DFT theoryThe process of protonation of N235 is essentially the process of bonding the H protons with the N atoms HOMO lone pair electrons.Cyanex272 easily forms dimers and trimers spontaneously.During the hydrogen bond formation of dimers,the HOMO electrons of P=O bond O shift to the LUMO of OH bond H,which increases the electron energy around OH bond H.The formation of the polymer weakens the high-energy electron orbit near the P=O bond O atom,reducing the ability of the site to undergo electron transfer.The essence of vanadium extraction in the mixed system of N235 and Cyanex272 is that the OH of protonated N235 and the OH of Cyanex272monomer compete for the hydrogen bond formation of P=O bond.The energy analysis of this process shows that the complexation reaction can form spontaneously.The formation of the P=O···H-N bond is accompanied by the dissociation of the dimer and the release of free Cyanex272.At the same time,the polarity of the OH bond of Cyanex272 in the complex is enhanced,and H~+is more ionizable,which makes it easier to exchange reaction with VO2~+.The mixed extraction system has the ability to extract both anion and cationic vanadium ions,and also improves the extraction ability of vanadium ions in the acid leaching solution.更多还原