A Review on the Separation of Niobium and Tantalum by Solvent Extraction

Niobium and tantalum are found together in natural minerals. Leaching with concentrated acid solution or alkaline roasting followed by water/dilute acid leaching results in a solution containing these two metals. In this work, we reviewed the extraction and separation of Nb(V) and Ta(V) from leach liquors in the absence and presence of hydrofluoric acid by acidic, neutral extractants and amines. Several solvent extraction systems were compared in the light of the requirement of hazardous chemicals, extraction/separation efficiency, and stability/solubility of extractants. Since the cationic species of Nb(V) and Ta(V) are unstable in the aqueous solution, the application of acidic extractants for extraction and separation of these metals is limited. Amines can extract Nb(V) as well as Ta(V) irrespective of the presence of fluoride ion but the separation of these metals from the loaded amines should be carried out in stripping process, resulting in process complexity. Another disadvantage encountered for amine is related to high viscosity in extraction process. Neutral extractants are considered as promising extractants which are effective to separate Ta(V) and Nb(V) from either non-fluoride or to moderate fluoride ion concentration in terms of extraction, separation and stripping efficiency. Compared to the traditional methyl iso-butyl ketone (MIBK) based system, methyl isoamyl ketone (MIAK) is found to be a promising extractant to separate Nb(V) and Ta(V).     

Pressureless sintering and properties of boron carbide composite materials

Boron carbide and Tantalum boride composites were prepared by pressureless sintering of B₄C with addition of TaC powder. The effect of TaC addition on the sinterability of boron carbide was studied. High densified ceramic with a relative density of 98.7% was obtained at sintering temperature of 2250°C. The composition and the microstructure of the dense composites are characterized by means of x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDX). The studies show that the composites contain boron carbide, TaB₂, and carbon phases with a homogeneous structure. In addition, the correlation between the composition and the electrical conductivity was investigated. The electrical conductivity of the composite increased with increasing addition of TaC, and a change in conduction behavior from semiconducting to metallic was observed. High hardness value of 28.49 ± 1.33 GPa was obtained by the sample with 30 wt% TaC addition.     

ICP-AES法测定六氟化铀中的微量钽

以TBP-萃淋树脂萃取分离基体铀,通过对发生器功率、雾化气流量、样品提升量等进行条件试验,建立了六氟化铀中杂质元素钽的ICP-AES测定方法。在取样量为250 mgU时,方法的检出限为0.60μg/gU,方法的加标回收率为86.6%~113.4%,相对标准偏差小于12%。     

激光增材制造难熔金属研究进展

难熔金属由于具有优异的综合性能而广泛应用于航空航天、装备制造、核工业及生物医疗等领域。但是由于高熔点及高韧脆转变温度的特点,尚存在加工制造困难、生产周期长、对设备要求高等问题,从而限制了其应用与发展。激光增材制造是近年来新兴的数字化制造技术之一,为制造和加工难熔金属提供了新的发展思路。本文重点介绍了近年来激光增材制造难熔金属的热点领域,包括钨及钨基重合金、纯钼及钼硅硼合金、铌硅及铌钛合金和多孔钽,对尚存在的问题进行了总结,最后对激光增材制造难熔金属未来的发展方向进行了展望。     

青海交通社铌钽矿床地质特征及控矿规律

交通社铌钽矿床是阿尔金造山带新发现的铌钽矿床。文章以该矿床为研究对象,通过开展矿床地质特征调查,研究总结矿床地质特征及控矿规律。交通社铌钽矿区划分的4条矿化带,其中Ⅰ、Ⅱ、Ⅳ矿带均为金矿;Ⅲ矿带为铌钽矿,圈出铌钽矿体6条,长200~2640m,厚度为4. 87~12. 35 m,品位(Nb2O5) 0. 016%~0. 034%,矿体受碱长花岗岩控制。矿化蚀变主要有:矽卡岩化、硅化、碳酸盐化和云英岩化,铌钽矿与矽卡岩化、云英岩化关系密切,铌钽矿矿石类型主要有铌铁矿石、钽铁矿石。铌钽矿受碱长花岗岩控制,位于碱长花岗岩与矽卡岩化带附近,铌钽矿体明显增高,矿体向深部具有品位变富厚度变大的趋势,铌钽矿中的铌、钽元素来源于碱长花岗岩,碱长花岗岩为成矿提供物质、能量、流体等多种条件,使矽卡岩化带附近大量的Nb、Ta等稀有、稀土元素在二云母片岩中富集,形成了铌钽富矿体。文章针对矿区的实际情况,提出并分析了找矿标志及找矿潜力,以期取得找矿突破。     

钽表面微弧氧化陶瓷层的抗氧化性能

通过微弧氧化技术在钽金属表面制备陶瓷层,并采用SEM观察了陶瓷层的表面形貌,采用增重法对陶瓷层的抗氧化性能进行研究,探讨了放电电压、放电频率、氧化时间对陶瓷层抗氧化性能的影响。结果表明,对钽金属表面进行微弧氧化处理,可以显著提高钽金属的高温抗氧化性能,对高温抗氧化性影响最大的两个原因是微弧氧化陶瓷层中铝元素的含量和致密性。在电压400V、1 000Hz、20min时陶瓷层的高温抗氧化性最好。     

Rapid and efficient deoxygenation of sulfoxides to sulfides with tantalum(V) chloride/sodium iodide system

TaCl₅/NaI system converts a wide range of sulfoxides to the corresponding sulfides in high yields with short reaction times, under mild conditions. It is worth mentioning that this protocol is chemoselective and tolerates various functional groups (such as –Br, –Cl, –OCH₃, –CHO, and –NO₂) and double bond.     

棒状及纤维状氧化钽的制备

以自制高纯钽酸为原料，通过氨水中和、沉淀、干燥和高温煅烧，制备了不同取向结构形貌（棒状或纤维状）的氧化钽粉体。研究了反应温度、反应物浓度以及分散剂含量对氧化钽颗粒尺寸大小和形貌的影响。利用XRD、SEM对氧化钽粉体进行了表征分析。结果表明：在氧化钽的制备过程中，随着煅烧温度的升高，氧化钽粉体的结晶度提高；氨水浓度越大，氧化钽颗粒形貌越均匀规整，但是过高的氨水浓度会降低氧化钽粉体形貌的均匀性；制取二维取向结构棒状氧化钽粉体的最佳反应温度为40~50 ℃；制取一维取向结构纤维状氧化钽的适合的分散剂PEG6000用量为1%。     

电容器级钽粉关键技术与开发研究

引述了Ta电容器与Al电容器、多层陶瓷电容器相比突出的性能与应用特征，分析了Ta电容器片式化、小型化促进电容器级Ta粉高比容化发展的新趋势，叙述了航空、航天和军工领域对高压电容器高可靠性能的需求，以及对中高压Ta粉向更高电压、更低SER方向发展的引领，回顾了电容器用高比容Ta粉、中高压Ta粉发展应用进程，介绍了经典氟钽酸钾（K2TaF7）金属Na还原法、电子束熔炼法、球磨片式化法生产的高比容Ta粉、高压Ta粉、中压（片状）Ta粉的性能、产品品级及关键技术，分析了30～80kμFV／gTa粉耐压性能影响因素，介绍了Ta粉高比容化、高压化新技术、装置、产品形貌、性能及优缺点，在此基础上提出了电容器级Ta粉高比容化、高压化创新进步的思路。