伯胺萃取钒铬分离的界面污物控制与钨钼分离研究
文献类型：学位论文
| 作者 | 宁朋歌 |
| 学位类别 | 博士 |
| 答辩日期 | 2009-10-09 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 过程工程研究所 |
| 导师 | 张懿 |
| 关键词 | 溶剂萃取 伯胺 界面污物 钒铬 钨钼 |
| 其他题名 | Study on the interfacial crud produced in the extraction and separation of V and Cr, and the separation of W and Mo by primary amine |
| 学位专业 | 化学工艺 |
| 中文摘要 | 本文针对含钒铬钨钼等多金属废料综合利用的分离纯化问题，开展了伯胺萃取分离钒和铬、钨和钼的研究，重点解决萃取过程中经常遇到的界面乳化问题，并深度提取和回收有价金属。本文主要从两个方面进行研究，即钒铬萃取分离过程和界面污物及钨钼的萃取分离，取得了以下创新性结果： 1）在实验室钒铬萃取分离方法研发成功的基础上，针对过程中出现的界面污物的形成行为进行了详细的研究。结果表明，该体系界面污物主要是由固体微粒作为乳化剂而稳定存在的，生成原因主要有四个方面：①萃原液中的不溶性二氧化硅；②铝、铁、钙等元素的水解产物；③萃取过程中可溶性盐硫酸钠的结晶；④过程中的氧化还原产物。其它因素如萃原液初始pH值、萃取剂类型、浓度、相调节剂类型、相比和接触时间也在一定程度上影响了界面污物的生成量。该水包油型界面污物中元素分布很不均匀，元素含量随初始萃原液pH值的变化而变化。 2）钒铬萃取体系界面污物的形成过程和稳定机理为：二氧化硅等不溶物在乳化液滴周围形成一层致密的固体膜，抑制了分散相油滴的聚并，在萃取振荡的强剪切过程中，主体水相的可溶性硫酸钠会在乳化液滴界面结晶出来，为界面污物的稳定提供了又一保证；体系长期运行时，六价铬会被还原为三价铬，该还原产物将会稳定更多的乳化液使界面污物增多，同时，固体微粒对有机物质的吸附将使界面膜更加坚固；萃原液中二氧化硅的交联将会增加液滴间的空间阻力，界面区域固体微粒的电效应也使液滴不宜聚并。在复合固体界面膜、液滴间的空间效应和固体微粒的双电层效应的共同作用下，形成了稳定的界面污物。从热力学稳定性、动力学稳定性和聚结稳定性三个方面进一步研究表明，界面污物是在多相复合界面膜、扩散双电层及空间稳定机理的共同作用下而稳定存在的。 3）界面污物的防治方法包括：深度净化实际萃原液、改变有机相等。用0.22 μm的水系纤维膜预处理萃原液，深度过滤两次后萃取有利于减少界面污物的生成量；工业上可行的预防界面污物的方法分别为：采用15%(v/v)的LK-N21作为萃取剂，或用正己烷作为稀释剂，或增加相调节剂LK-N21X的浓度至30%(v/v)。 4）在实验室钒铬萃取分离和界面污物研究的基础上，重点对企业实际料液进行中试试验和工业化试验研究，主要考察了实际运行过程中钒铬萃取率的变化和萃取剂损失情况，以及最终产品的纯度，结果表明，整个过程中钒铬分离效果良好，萃取剂损耗低于2%，其损失主要是萃取过程中在油水两相之间生成了界面污物，夹带了萃取剂，大量的钒经萃取提纯和后续处理后，得到的五氧化二钒纯度超过99.5%。 5）以正钨酸根和正钼酸根电荷密度的不同为出发点，展开伯胺溶剂化萃取分离钨钼的研究。针对高钨低钼、高钼低钨和钨钼浓度相当三种情况，分别详细研究了溶液中的钨钼分离行为。结果表明，伯胺用于高钼低钨或钨钼浓度相当体系中的钨钼分离效果较好，但不适合分离纯化高钨低钼溶液。对于1.0 g/L钨和50 g/L钼的溶液中，萃取剂选用伯胺N1923，浓度为0.051 M，以硫酸溶液为酸介质，在15 ℃下接触萃取10 min，平衡pH值达到7.07左右，钨钼分离因子可以达到195.1，二级逆流萃取试验结果表明，萃余液钨钼质量比可达2.876E-5，完全满足纯钼酸钠中钨含量不超过万分之一的要求。钨钼浓度相当溶液中的钨钼分离的较优条件为：平衡pH值为7.73，接触时间为10 min，萃取温度为15 ℃，萃取剂伯胺N1923体积浓度为15%，经过四级萃取能将钼盐溶液纯化，萃余液中W/Mo比降低为1/1000。在此基础之上，提出了钨钼分离过程的工艺路线及伯胺萃取钨钼的反应机理。 |
| 英文摘要 | In order to resolve the problem of the separation and purification of metals in scraps, a detailed study has been carried out to investigate the extraction of V、Cr、W、Mo by primary amine, resolve the difficulties encountered in practice, and deeply purify and recycle these metals. The framework of this thesis includes the extraction separation of V and Cr and the interfacial crud produced in the process, and the extraction separation of W and Mo. New progress and innovative results were achieved as follows: 1) In this paper, the interfacial crud was investigated in detail after the separation of vanadium and chromium was solved in flask, including the effects of various extraction conditions on the formation behavior of interfacial crud. It was found that solid particles as the emulsifier could stabilize the interfacial crud, which composed the major cause of the crud formation. The solids were the dioxide silicon, the hydrolysates of Al or Fe, the crystals and the reaction products by redox. At the same time, other conditions including the initial pH value of the real leaching solution, the type and the concentration of the extractant, the type of the modifier, the phase ratio and the contact time, influenced on the percentage of the interfacial crud produced to some degree. The crud was verified to be oil in water, with some fine solid particles in the water phase, and the elements in it are not homogeneous in different parts. During the long-term run, the Cr6+ was reduced to Cr3+ probably by unsaturated materials in kerosene diluent, and the organic phase may be also changed. 2) The probable mechanism of the interfacial crud formation was put forward. The solids present in the real leaching solution exert a stabilizing effect on the crud, based on which Na2SO4 crystallizes at the interface of the crud. Furthermore, the Na2SO4 crystals strengthen the crud conversely. Cr2O3 produced in the long-term circuits stabilize more emulsion to increase the amount of the crud. These solids form the interfacial membrane around the liquid drop, which was consolidated by the organic materials adsorbed by the solids. Furthermore, the three-dimensional effect of the dioxide silicon and the electric effect of the solids inhibit the drop-drop coalescence. Thus, the stable interfacial crud forms. In view of the stabilities of thermodynamics, kinetics and coalescence, the stability mechanism of the interfacial crud was confirmed to be the combined effect of the stabilization mechanism of the multiphase composite interface membrane, the stabilization mechanism of the diffusing double layer, and the stabilization mechanism of the space. 3) The measures such as purifying completely the real leaching solution, changing components of the organic phase were justified to prevent interfacial crud. Pretreatment of the real leaching solution by 0.22 μm cellulose membrane can avoid the crud produced. The applicable preventing methods in practical production are the application of LK-N21 (15%) as extractant, or n-hexane as diluent, or LK-N21X with a concentration of 30% (v/v) as the modifier. 4) Pilot and industrial experiments were carried out in the plant, respectively, using real leaching solution based on the results of laboratory investigation, and the extraction efficiency was evaluated according to the extraction percentage of V and Cr, the loss of extractant and the purification of products. The results indicate that the separation of the two metals is thorough in the whole process, and the extractant loses a little because of the interfacial crud produced at the interface between the aqueous and organic solution. The purity of the product, i.e. vanadium pentoxide, reaches up to 99.5%. 5) The separation between tungsten and molybdenum by primary amine was investigated from three types of solutions, including the solution 1 with high W and low Mo concentration, the solution 2 with high Mo and low W, and the solution 3 with the comparable concentrations of W and Mo based on the difference of ionic charge densities. And the results indicate that the extraction method is feasible to the extraction and separation of tungsten and molybdenum in solution 2 and solution 3, but not applicable to solution 1. Furthermore, the operation conditions were optimized. In case of solution 2, the optimal conditions are as follows: using 0.051 M of primary amine N1923 as extractant and H2SO4 solution as extraction medium, the extraction was performed for 10 min at 15 ºC, and the equilibrium pH value was adjusted to about 7.07. Accordingly, the separation factor of W to Mo reaches up to 195.1 in a one-stage extraction, and the deep-removal of tungsten can be accomplished by a two-stage extraction. The results of simulation experiments for the two stage countercurrent extraction indicate that after two stage extraction the ratio of W/Mo lowered to 2.876E-5 in raffinate, which fully meets the requirements of W/Mo being not over 0.0001 in the high pure sodium molybdate. The solution of NaOH can easily strip the loaded organic phase for 6 min at 27 ºC with the ratio of nNaOH to (nW+ nMo) equaling 2. In case of solution 3, the optimal conditions are with the equilibrium pH value of 7.73, contact time of 10 min, temperature at 15 ºC and using 15% primary amine N1923 as extractant. Sodium molybdate can be purified after the simulation experiments with four stage countercurrent extraction, and the ratio of W/Mo is about 0.001 in the raffinate. The flow-sheets of the separation of W and Mo and the reaction mechanism for the extraction of the two metals by primary amine were proposed according to these results. |
| 语种 | 中文 |
| 公开日期 | 2013-09-13 |
| 页码 | 150 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1265]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 宁朋歌. 伯胺萃取钒铬分离的界面污物控制与钨钼分离研究[D]. 过程工程研究所. 中国科学院过程工程研究所. 2009. |
入库方式： OAI收割
来源：过程工程研究所
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