| 题名 | 铌钽复杂矿亚熔盐分解清洁工艺基础研究 |
| 作者 | 周宏明 |
| 学位类别 | 博士 |
| 答辩日期 | 2004 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 中国科学院过程工程研究所 |
| 导师 | 张懿 |
| 关键词 | 亚熔盐 氢氧化钾 妮担铁矿 动力学 妮酸钾 清洁工艺 |
| 其他题名 | Fundamental Research on the Clean Process for Decomposing Niobium-tantalum Ore with Sub-molten Salt of Potassium Hydroxide |
| 学位专业 | 化学工艺 |
| 中文摘要 | 铌、担属于稀有难熔金属，其金属和合金已被广泛应用于钢铁、电子等高新技术领域，是很重要的稀有金属。从妮担矿石中提取妮、担及其化合物的关键技术是矿石的分解。工业上湿法冶金分解妮担矿的主要方法是氢氟酸分解法，但会造成严重氟污染。本论文针对目前妮担矿湿法冶金行业氢氟酸传统工艺存在的严重氟污染及对低品位难分解妮钮矿分解率低的问题，提出了以氢氧化钾亚熔盐介质取代传统毒性氢氟酸作为妮担矿的分解介质，从生产源头消除氟污染。氢氧化钾亚熔盐具有蒸汽压低、沸点高、高反应活性及流动性能好等良好特性，为性能可控的高浓度非常规介质。本论文围绕妮担矿亚熔盐分解清洁工艺新过程的基础研究与过程优化，取得了以下几方面的新进展：（1）测定了30℃和80℃时的K2O-Nb2O5-H2O三元水盐体系的溶解度及相图，并通过热力学计算对妮担铁矿中主要组分在氢氧化钾亚熔盐体系中浸出时的可能生成产物进行了分析。实验研究了Nb2O5、Ta2O5及其混合物在氢氧化钾亚熔盐中的溶解行为，确定了不同浸出工艺条件下的转化产物。结果表明，氢氧化钾高浓区有利于得到水溶性的六妮酸钾；但温度越高，则促使生成不溶性的偏妮酸钾沉淀；Ta2O5在不同反应温度和不同氢氧化钾浓度的亚熔盐中，均只得到不溶性的偏担酸钾沉淀；Nb2O5与Ta2O5的质量比分别为1：1和1：3的混合物，在氢氧化钾亚熔盐中的溶解行为与纯Nb2O5的溶解行为类似。（z）研究了氢氧化钾亚熔盐浸出妮担铁矿的反应动力学，提高反应温度和氢氧化钾浓度或减小妮钮铁矿粒径能显著提高妮的浸出速率；浸出过程符合固膜扩散控制的收缩未反应核模型，受产物层的内扩散所控制，表观活化能为72.2kJ／mol；SEM和EDXA的分析结果也证明了固相产物层的存在，其主要组成为铁化合物；〔Nb,Ta）6O19］8-离子通过固相产物层的内扩散为浸出过程的控制步骤。在此基础上对浸出工艺条件进行了优化，实验结果表明，氢氧化钾亚熔盐浸出低品位妮担铁矿时，矿石分解完全，妮、担提取率均为％％以上，较传统氢氟酸法提高10％以上；与碱熔融分解法相比较，分解温度由800℃下降到300℃，理论推算碱耗量由3t碱／t矿下降到0.55t碱／t矿，操作过程为常压，从而可降低设备费用和生产成本，并提高妮担矿资源的利用率。（3）新工艺过程的研究表明，氢氧化钾亚熔盐分解妮担铁矿所产生的不溶性偏妮、担酸钾与铁锰渣经磁选分离后，偏妮、担酸钾返回亚熔盐分解工序，不造成妮、担在渣中的积累，妮、担总回收率达99％以上，铁锰渣含妮、担小于0.2％，并成分简单，便于综合利用。过量的氢氧化钾溶液经蒸发浓缩后，可返回再用于矿石分解工序，六妮、担酸钾结晶经硫酸分解后得到水合氧化妮、担混合物，作为进一步制备妮担系列产品的中间体；而硫酸钾溶液可通过蒸发结晶，得到副产硫酸钾。 4）在研究Nb2O5溶解行为研究的基础上，探索了采用氢氧化钾亚熔盐法制备偏妮酸钾陶瓷粉末材料的新工艺。与传统的碱熔融法相比较，反应温度由1100℃下降到200℃，反应时间由3Oh下降到30min左右，从而可大幅度降低能耗。本研究作为中科院过程工程研究所亚熔盐化工冶金技术平台的重要组成部分，提出的妮担矿亚熔盐分解工艺新过程的原则流程，通过进一步完善和工程放大研究，有望实现妮担矿的清洁转化。 |
| 英文摘要 | Among the rare metals with high melting point, niobium and tantalum have been applied widely in the fields of steel, electronic and other high-tech industries. The decomposition of the ore is the key step in extracting niobium, tantalum and their compounds from niobium-tantalum ore. At present, most minerals containing niobium and tantalum are decomposed with concentrated hydrofluoric acid, bringing serious environment pollution of fluorin. Moreover, it is hard to decompose the refractory niobium-tantalum ore with hydrofluoric acid. A new process for leaching the low-grade niobium-tantalum ore with KOH sub-molten salt was proposed by the Institute of Process Engineering, Chinese Academy of Sciences, with an objective to eliminate the fluorin pollution at the source. KOH sub-molten salt is a unconventional concentrated medium with controllable properties: such as low vapour pressure, high boiling point, high reaction activity and good fluidity. Fundamental research and process optimization have been carried out on the new clean process for decomposing niobium-tantalum ore with KOH sub-molten salt. The innovative research results are summarized as follows: (1) The solubilities of the KzO-NbiOs-HaO ternary system were studied at 30°C and 80°C by isothermal method, and the corresponding equilibrium diagram was plotted. By thermodynamic calculation, the possible products of the main compositions were investigated in the leaching process of niobium-tantalum ore with KOH sub-molten salt. The dissolution behavior of NbiOs, TaaOs and their mixture in KOH sub-molten salt were examined, and their corresponding converted products under different reaction conditions were investigated. It was found that the reaction temperature and KOH concentration have significant influence on the dissolution behavior of NbaOs. Under a certain reaction temperature, increasing KOH concentration helps to form of soluble potassium niobate, and under a certain KOH concentration, increasing the reaction temperature helps to form insoluble potassium niobate. Under the studied reaction conditions, only insoluble potassium tantalate was obtained in KOH sub-molten salt system. The dissolution behavior of the mixture of M^Os and Ta2Os, with mass ratios of 1:1 and 1:3, is similar to that of Nb2O5 in KOH sub-molten salt. The leaching kinetics of niobium from a low-grade niobium-tantalum ore with KOH sub-molten salt was studied. It was indicated that increasing the reaction temperature and KOH concentration or decreasing the particle size of the ore significantly improves the leaching rate of niobium, and the leaching process was well interpreted with a shrinking core model under diffusion control. According to the Arrhenius expression, the apparent activation energy for the leaching of niobium was estimated to be 72.2 kJ.mol"1. Combining the kinetic experimental results with the results of the SEM and EDAX analysis results, it was proved that, a solid product layer is formed on the surface of the unreacted core during the leaching process of niobium-tantalum ore with KOH sub-molten salt and its main composition is an iron compound, and that the diffusion of [(Nb,Ta)6Oi9] " was presumed to be the rate-controlling step of the leaching process. Additionally, the technical parameters of the leaching process were optimised. The results showed that niobium-tantalum ore can be decomposed completely, and the leaching rates of both niobium and tantalum are above 96%, which were 10% higher than those in the hydrofluoric acid process. Compared with the alkali fusion process, the leaching temperature was decreased from 800°C to 300°C, and the alkaline consumption for one ton of the ore was decreased from 3 tons to 0.55 tons. Moreover, the new process was operated under atmospheric pressure. Consequently, both the equipment and production costs were decreased, and the resource utilizational of niobium-tantalum ore was increased. In the new process, potassium niobate and ferro-manganese residue obtained after leaching of niobium-tantalum ore with KOH sub-molten salt can be separated by magnetic selector directly. Potassium niobate can be recycled to the ore decomposition process and the ferro-manganese residue can be utilized comprehensively for its relatively simple composition. Excessive KOH solution could be recycled to the ore decomposition process after concentrating by vaporization. After potassium hexaniobate and potassium hexatantalate were decomposed by sulfuric acid, niobium hydroxide and tantalum hydroxide were obtained, and could be used as the intermediate products to further prepare other niobium/tantalum products. The by-product potassium sulfate was obtained by vaporization crystalization. (4) Based on the dissolution behavior of M^Os, a new process for preparing ceramic powder of potassium niobate with KOH sub-molten salt was developed. Compared with the alkali fusion process, the reaction temperature was decreased from 1100°C to 200 °C, and the reaction time was decreased from 3 Oh to 30min. Therefore, the energy consumption of this process was decreased remarkably. Based on the research results above, the principle flowsheet for decomposing niobium-tantalum ore with KOH sub-molten salt was proposed. The clean conversion of niobium-tantalum ore is expected to be achieved by further betterment and scale-up of the new process. |
| 语种 | 中文 |
| 公开日期 | 2013-09-16 |
| 页码 | 131 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1416]  |
| 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 | 周宏明. 铌钽复杂矿亚熔盐分解清洁工艺基础研究[D]. 中国科学院过程工程研究所. 中国科学院过程工程研究所. 2004. |
| 个性服务 |
| 查看访问统计 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
修改评论