梯级微孔金属隔膜电解短流程清洁制备钒产品应用基础研究

Vanadium oxides are important raw materials in metallurgical and chemical industries. The cleaner and effective manufacture of vanadium oxide is one of the major subjects. The current conversion methods of vanadium compounds cannot be widely used due to the environment issues and technical problems. This project focused on the sodium orthovanadate intermediate product from vanadium extraction process of Sub-molten Salts. Based on the principle of membrane electrolysis, a simple and cleaner synthesizing method of vanadium product by step membrane electrolysis using porous metal membrane was proposed in this project. The porous metal membrane and step electrolysis were separately used to achieve the good migration of big vanadate ions and the selective separation of V and Na. The competitive migration law in the channels of the metal membrane and adjusting method for various ions were investigated. The concentration law and separation method for different ions during step membrane electrolysis were also studied. Based on these laws, the optimization design and energy consumption calculation of the whole membrane electrolysis were performed. This project revealed the effects of membrane interface and micro-electric field near channels on the migration of various ions, and established a distribution coefficient model of V/Na for the step membrane electrolysis. A new electrolysis system with optimal energy consumption was established. It can provide theoretical support for the cleaner and effective separation of V and Na, and simple synthesis of vanadium compounds. This work is expected to promote green update of vanadium production technology and comprehensive utilization level of characteristic mass vanadium titanomagnetite resources in China.

钒氧化物是重要的冶金、化工原料，钒氧化物的清洁、高效制备是钒化工行业的重要研究课题。本项目以亚熔盐法提钒工艺流程的钒酸钠中间体为研究对象，针对后续钒产品转化过程中环境挑战大、技术瓶颈高的难题，基于膜电解技术基本原理，提出了梯级微孔金属隔膜短流程清洁制备钒产品的新方法。利用微孔金属隔膜和梯级循环电解，解决大尺寸钒酸根离子的通透性问题以及V/Na选择性分离问题。通过深入研究不同荷电离子在金属隔膜孔道中竞争性迁移规律及调控方法，梯级电解过程不同荷电离子的富集规律及分离方法，电解分离过程的能量消耗规律及电解体系优化设计，揭示隔膜界面、孔道区域电场对于不同荷电离子迁移过程影响规律，构建梯级电解过程中V/Na分配比数学模型，建立能耗最优化的电解新体系，为钒酸钠中V/Na高效清洁分离及钒产品的短流程制备过程提供理论指导，对推动我国钒产业绿色升级及提高大宗特色钒钛磁铁矿资源综合利用水平具有重要的科学意义。

钒氧化物是重要的冶金、化工原料，钒氧化物的清洁、高效制备是钒化工行业的重要研究课题。本项目以亚熔盐法提钒工艺流程的钒酸钠中间体为研究对象，针对后续钒产品转化过程中环境挑战大、技术瓶颈高的难题，开发了钒酸钠膜电解分离-偏铵清洁沉钒新工艺。重点研究了电解体系中钒酸根离子存在形态规律、多级金属隔膜电解及V/Na分离规律、离子膜电解钒钠分离及杂质累积规律、铵盐沉钒清洁制备钒产品工艺以及膜电解工艺能量最优化设计。理论研究表明，随着电解pH的降低，溶液中钒酸根离子会发生聚合，逐渐由单体的VO43-聚合为V2O74-、V4O124-、V10O286-、HV10O285-、H2V10O284-等多种形态，膜电解时溶液pH=2，钒酸根离子主要H2V10O284-形式存在。Ti金属隔膜可实现钒酸钠溶液中V与Na的分离，通过三级梯度电解，溶液中V/Na摩尔比可从2.46提高至18.49。但金属隔膜电解能耗较大，电解1tV2O5产品的直流电耗约为4302kwh/t。离子膜电解方法可显著降低电解能耗，本项目采用F8080三室隔膜电解，在电流密度500A/m2，温度70℃，阴极NaOH浓度18g/L条件下，电解1tV2O5产品的直流电耗为2868kWh，电流效率达到95%。针对电解后的阳极液的钒产品转化过程，开发了氨水沉钒和偏铵沉钒两种工艺路线。通过系统研究各个沉钒工艺参数对沉钒率和钒产品纯度的影响，优选偏铵沉钒作为阳极液沉钒的最佳工艺路线。在沉钒温度80℃，加铵系数1.5， V/Na摩尔比2.55条件下，可实现沉钒率69.91%，所得多钒酸铵产品纯度99.9%。偏铵沉钒工艺路线物料消耗少、能耗低，具有显著的优势。偏铵沉钒工艺与膜电解工艺相结合，可实现V与Na的高效解离以及钒产品的高效制备。本项目对于解决钒产品转化过程中的资源环境问题，支撑钒生产技术的绿色升级，以及提高大宗特色钒钛磁铁矿资源综合利用水平具有重要的科学意义。