Knowledge Management System Of Institute of process engineering,CAS
|Thesis Advisor||张懿 ; 徐红彬|
|Place of Conferral||北京|
|Keyword||无水氯化铝 低温氯化 氨解 提纯 高纯五氧化二钒|
随着科技的不断进步，全钒液流电池、钒铝合金、锂电池以及催化剂等众多领域对高纯度五氧化二钒产品的需求量越来越大。高纯五氧化二钒的传统制备工艺大都停留在实验室研究阶段，面临着成本高、流程长、污染重、产品纯度低等问题，高纯五氧化二钒产品的低成本短流程清洁制备技术已成为钒化工行业的研究热点。本论文提出了一种通过无水氯化铝低温氯化分离工业级五氧化二钒产品中铁、铝、硅等杂质进而提纯并制备高纯五氧化二钒的新方法。首先，通过理论分析和探索试验确定了原则工艺流程；然后，系统研究了氯化反应的工艺条件和反应机理，以及氯化反应所得三氯氧钒中间体氨解过程中各因素对沉钒率和产品纯度的影响规律，并制备得到了高纯五氧化二钒产品；最后，进一步拓展了原料范围，选用三种不同的含钒原料对整体流程进行了验证。本论文在以下几方面取得了创新结果：（1）在热力学计算、物性分析及探索试验的基础上，确定了无水氯化铝低温氯化法制备高纯五氧化二钒新工艺的整体流程。研究结果表明，无水氯化铝与五氧化二钒之间的氯化反应在低温下可行，且结合各杂质氯化物的物化性质分析，确定该氯化反应有利于原料中钒与其他杂质的分离。反应温度为160℃时，氯化反应发生并生成三氯氧钒中间体，中间体经过氨解煅烧过程制备出高纯V2O5。（2）系统研究了反应温度、原料配比、添加剂用量等因素对氯化反应的影响规律，确定了较适宜的氯化反应工艺条件，并借助TG-DSC、SEM、EDS等手段分析了氯化反应的机理。在反应温度为170℃、无水氯化铝与原料中五氧化二钒的化学计量比为3:1、氯化钠添加量 x=nAlCl3/(nAlCl3+nNaCl)=0.6且添加氯化钠后，反应时间可缩短到1 h，三氯氧钒产品收率最高可达83.35%，反应产物纯度≥99.95%。氯化反应过程中有中间体AlOCl生成，最终AlCl3全部转化成Al2O3。（3）研究了氨解过程各工艺参数对五氧化二钒产品纯度和沉钒率的影响规律，确定了较适宜的氨解工艺参数。在钒浓度介于13.4 ~ 68.8 g/L之间、氨解温度为35℃、加氨系数为0.8 ~ 1.0、搅拌强度为15 r/s时，氨解反应过程钒收率最高。借助ICP、XRD、XRF、XPS等手段，对五氧化二钒产品的纯度及表面元素化学计量比进行了详细的分析，确定制备的五氧化二钒产品纯度≥99.97%。（4）分别以钒渣钠化提钒工艺生产的工业级五氧化二钒（96.487%）、石煤提钒工艺生产的工业五氧化二钒（96.675%）以及钒渣（25.46% V2O5）为原料，采用低温氯化法工艺，制得了纯度分别为≥99.84%、≥99.97%、99.70%的五氧化二钒产品，为含钒原料氯化提钒的研究提供了新思路。
With the development of modern industry and technology, high-purity vanadium pentoxide finds more and more applications in many fields including vanadium redox flow battery (VRB), vanadium- aluminum alloy, lithium battery and catalyst. Due to the high cost, long flow sheet, heavy pollution and low purity, most of the conventional methods for preparing V2O5 are still in the laboratory stage. The investigations on preparing high-purity V2O5 with a lower cost, shorter and cleaner process has been attracted increasing attention.In this paper, a novel low temperature chlorination method with anhydrous aluminum chloride was proposed. Vanadium can be separated alone from Fe, Al, Si and other impurities, and high-purity vanadium pentoxide can be obtained. Firstly, the technological process was determined on the basis of theoretical analysis and probe test. Then, the conditions and mechanism of chlorination reaction process were systematically studied. In addition, with VOCl3 as the raw material of hydrolysis reaction, the effects of hydrolysis conditions on precipitation rate and product purity were also discussed. High-purity V2O5 was finally obtained. And with three kinds of raw materials, the whole process of preparing high-purity V2O5 was confirmed.The main innovative results of this paper can be summarized as follows:(1) Based on thermodynamic analysis, property analysis and probe test, the whole process to prepare high-purity V2O5 was confirmed. The chlorination reaction between AlCl3 and V2O5 is thermodynamically possible. By combination with the boiling points of the different metal chlorides, it is speculated that using AlCl3 as the chlorination agent could achieve an effective vanadium separation from other impurities at low temperature. The chlorination process of V2O5 with AlCl3 produced intermediate VOCl3 at the temperature of 160℃. Then, after hydrolysis and calcination of intermediate, high-purity V2O5 was obtained.(2) The effects of reaction temperature, raw material ratio, the dosage of additive and others were systematically studied. The optimal conditions of chlorination reaction were determined, and in combination with the analysis of TG-DSC, SEM, EDS, the chlorination reaction mechanism was researched. The optimal conditions are determined as follows: the reaction temperature is at 170℃, the a mole ratio of V2O5:AlCl3 is at 1:6, the dosage of sodium chloride of x=nAlCl3/(nAlCl3+nNaCl)=0.6. Under the optimal conditions, the reaction time is decreased to 1 h, the extraction of vanadium is 83.35%, and the purity of VOCl3 is achieved as high as 99.95%. The intermediate AlOCl is produced in the process of chlorination reaction. Finally, AlCl3 is all transformed into Al2O3(3) The effects of hydrolysis conditions on precipitation rate and the product purity were investigated. The optimal hydrolysis conditions are determined as a vanadium concentration of 13.4 to 68.8 (V2O5) g/L, an ammonium adding coefficient of 0.8 to 1.0, a temperature of 35 ℃, and a stirring intensity of 15 r/s. Under these conditions, the precipitation rate reaches the maximum value. The purity and the surface information of the obtained product V2O5 are carefully identified by using the analysis of ICP, XRD, XRF and XPS. V2O5 with a purity of 99.97% at least is obtained.(4) Three kinds of V2O5 raw materials, extracted from vanadium titano-magnetite, stone coal and vanadium slag, with an original purity of 96.487%, 96.675%, and 25.46%, respectively, were employed to purify and prepare high-purity V2O5. The purities of the obtained V2O5 products were found to be higher than 99.84%, 99.97%, and 99.70% respectively. It was confirmed that, the method proposed in this paper provides a new idea for purifying and preparing high-purity V2O5.
|姜单单. 氯化铝低温氯化法五氧化二钒提纯工艺研究[D]. 北京. 中国科学院研究生院,2017.|
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