Niobium and tantalum: State of the world market,application fields,and sources of raw materials. Part 2

Niobium and tantalum are rare refractory metals of large industrial value. Their reserves belong to “critical” raw materials, which leads to the necessity of evaluating the risks associated with the presence of primary and technogeneous raw-material sources of niobium and tantalum and with the influence of these factors on the offer and demand for these metals and their compounds, allowing for traditional and new application fields. World reserves of niobium and tantalum are analyzed and the dynamics of varying the structure of raw materials base and production solutions implemented and proposed for their processing is considered. A modern market of niobium- and tantalum-based materials is described, the main players on this market are noted, and tendencies in varying the structure of consumption of functional materials based on these metals is considered.     

Pyrometallurgy of Niobium,Tantalum and Vanadium—Development Work at Bhabha Atomic Research Centre

India has fairly substantial resources of vanadium and only small reserves of niobium and tantalum. Vanadium occurs in the vast deposits of titaniferrous magnetite located in Bihar Orissa and Karnataka. It is also occurring as a minor constituent in most of the bauxite deposits in the country. Niobium and tantalum occurs as niobium-tantalite in pegmatite deposits in mica mining belts of Bihar and Rajasthan. This mineral is also found in the cassiterite deposits of Baster in Madhya Pradesh.

This paper presents an overview of the development work carried out at Bhabha Atomic Research Centre on the process metallurgy of these three Group V metals starting from their indigenous resources. The coverage includes separation of pure individual elements, preparation of pure intermediates, techniques of reduction to metal and final purification.     

钽铌选矿理论与实践

简单介绍钽铌金属、钽铌矿和钽铌选矿的基本情况,着重把选矿的一般原理运用于钽铌选矿实际,全面系统地阐述钽铌选矿理论,从理论上分析并解决钽铌选矿的实际问题,以利于促进钽铌工业的发展。     

Technologies of secondary refractory rare metals (Review)

A short review of works by A.V. Elyutin et al. in the field of rare metals is presented. Technologies of the recovery of zirconium, hafnium, tungsten, tantalum, and niobium from various types of secondary raw materials, notably, scrap metal, scrap of refractory materials, wastes and scrap of hard alloys, and obsolete scrap of capacitors, are considered. Possibilities of increasing the purity of these metals by electrolytic refining and electron-beam melting are shown.     

Technology Trends in the Extractive Metallurgy of Zirconium,Titanium, Tantalum and Niobium

The reactive and refractory metals zirconium, titanium, tantalum and niobium have been in commercial production and industrial application over the last 30 years and more. With growing experience, there has been progressive improvement in process and equipment designs in the industrial practice. There has also been a continuous drive to develop entirely new processes, and to diversify the applications of these metals. The paper reviews the present status and the emerging trends, and places the Indian work in the global perspective.     

ICP-AES法测定稀土金属中的钛、钼、钨、铌和钽

针对试样特点拟定了加大称样量以减轻偏析,以浓硝酸溶解样品破坏碳化物,加入氢氟酸助溶,分离稀土基体同时络合钛、钼、钨、铌和钽的方法,无须基底匹配,采用工作曲线法成功地测定了金属镧、铈、镨、钕、钐、铕、钆、铽、镝、钇中的钛、钼、钨、铌和钽量,测定范围:0.0050%～0.50%。     

钨冶炼渣综合回收利用的研究进展

综述了钨冶炼渣中有用金属回收利用现状与研究进展,介绍了黑钨和白钨的冶炼工艺、钨、锡、钽、铌、钪回收工艺与理论、钨冶炼渣的减量化处理研究进展.重选和浮选工艺可回收钨锡,得到钨锡精矿后再进行冶炼,选矿工艺流程简单易工业生产且成本低,但适应性较差,对于较细物料无法有效回收,湿法冶金工艺可回收钨、锡、钽、铌、钪,适应性强但流程复杂,酸碱废水对环境影响大;钨冶炼渣减量化是综合利用的根本要求,目前主要用来制做水泥辅料、建筑胶砂、多孔材料、微晶玻璃等,介绍了目前减量化处理的研究现状.最后提出了问题与建议,钪钽铌稀有金属提取工艺的进步依赖萃取剂和离子交换树脂的发展,可利用材料领域内第一性原理和化学配位理论,研发选择性强的萃取剂和交换容量大的离子交换树脂,解决萃取剂选择性差、离子交换树脂交换容量小、废水量大的问题,从原子层面研究出相互作用机理,最终筛选出高效萃取剂及离子交换树脂.指出选冶联合工艺,开发短流程绿色提取技术、冶炼渣高附加值材料研制技术可能是今后研究的重点.      

Improved oxidation resistance of group VB refractory metals by Al+ ion implantation

Aluminum ion implantation of vanadium, niobium, and tantalum improved the metals’ oxidation resistances at 500 °C and 735 °C. Implanted vanadium oxidized only to one-third the extent of unimplanted vanadium when exposed at 500 °C to air. The oxidative weight gains of implanted niobium and tantalum proved negligible when measured at 500 °C and for times sufficient to fully convert the untreated metals to their pentoxides. At 735 °C, implantation of vanadium only slightly retarded its oxidation, while oxidative weight gains of niobium and tantalum were reduced by factors of 3 or more. Implanted niobium exhibited weight gain in direct proportion to oxidation time squared at 735 °C. Microstructural examination of the metals implanted with selected fluences of the 180 kV aluminum ions showed the following. The solubility limit of aluminum is extended by implantation, the body centered cubic (bcc) phases being retained to ～60 at. pct Al in all three metals. The highest fluence investigated, 2.4 × 10²² ions/m², produced an ～400-nm layer of VAl₃ beneath the surface of vanadium, and ～300-nm layers of an amorphous phase containing ～70 at. pct Al beneath the niobium and tantalum surfaces. All three metals, implanted to this fluence and annealed at 600 °C, contained tri-aluminides, intermetallic compounds known for their oxidation resistances. Specimens implanted to this fluence were thus selected for the oxidation measurements.     

钽、铌资源现状及其分离方法研究进展

概述了铌钽资源的分布状况、基本特征,对钽、铌的几种分离方法进行了介绍,重点介绍了萃取法的研究情况.     

电感耦合等离子体原子发射光谱法测定铌铁中铌钛钽硅铝磷

研究了在60 ℃的温度下用硝酸和氢氟酸溶解试样,然后用电感耦合等离子体原子发射光谱法（ICP-AES）同时测定铌铁中铌、钛、钽、硅、铝、磷的方法。为消除基体元素对被测元素的测定影响和克服在绘制校准曲线时因使用的铌铁标样中待测元素含量范围过窄而致使试样中的被测元素落在校准曲线线性范围之外,使用铌铁标样打底,加入适量标准系列溶液建立校准曲线。样品中高含量的铌采用高精密度测量法,从而提高了测定结果的准确性。本法用于测定铌铁标样中的铌、钛、钽、硅、铝和磷含量,测定值与国标法相符,测定结果的相对标准偏差小于1.5%。     

电感耦合等离子体原子发射光谱法测定铌钽精矿中铌和钽

准确分析铌钽精矿中铌、钽含量,对选冶及新材料的研发具有重要意义。实验以氢氧化钠作为熔剂,使用银坩埚,通过碱熔方式消解样品(熔融温度为720℃,熔融时间为20min),再酸溶后使用电感耦合等离子体原子发射光谱法(ICP-AES)测定铌钽精矿中铌、钽。对样品常见的消解方式、内标元素和分析线对的选择、共存元素的影响等因素进行了试验研究。结果表明:确定钴作为铌的内标元素,铬作为钽的内标元素,分析谱线及内标线为Nb 309.4nm-Co 345.3nm、Ta 240.0nm-Cr 284.3nm。铝、硅、钾、钠、钙、镁、铜、铅、锌、硫酸根、锰、磷、铬、钡、钴、砷、镍、锶、铍、钪、锡等不会对铌、钽的测定产生干扰。方法中铌和钽的检出限分别为0.007%和0.011%。按照实验方法测定4个铌钽精矿实际样品中铌和钽,并以多家实验室的测定平均值作为推荐值进行比对,结果表明,铌和钽测定结果的相对标准偏差(RSD,n=10)均小于0.6%,相对误差处于±5%之间。     

高纯钨、钼、钽、铌工业分析进展

评述了二十年来高纯稀有难熔金属领域钨、钼、钽、铌工业的分析进展,包括分光光度分析、原子吸收／发射光谱分析、质谱分析、中子活化分析和电化学分析等。引用文献50篇。通过对文献的多角度分析,反映了高纯钨、钼、钽、铌分析领域的行业布局,指出质谱分析等多元素同时痕量分析是高纯钨、钼、钽、铌工业分析的发展主流,但分光光度分析等单元素分析方法仍具有不可替代性。     

Diffusion-coating stability and the effects of copper and sulfur on refractory metal boriding

Studies have been made on the effects of copper and sulfur on structure and phase formation as well as growth in boride coatings on refractory metals (niobium, tantalum, molybdenum, and tungsten), in addition to measurements on the thermal stability of the diffusion layers.     

Vacuum diffusion welding of metalline carbides to high-melting metals

Conclusions The conditions of vacuum diffusion welding of zirconium, niobium, and tantalum carbides to the following high-melting metals: niobium, tantalum, molybdenum, and tungsten were investigated. Microstructural investigations of the weld seams were performed. The nature of the new phases that developed as a result of reaction diffusion was investigated by using the microhardness method, and assumptions concerning the mechanism of phase formation were made.     

电感耦合等离子体质谱法测定地球化学样品中铌钽钨锡

采用HCl-HNO₃-HF-HClO₄溶解地球化学样品,以50 mg/L酒石酸-1% HCl为测定介质克服了铌、钽、钨、锡易水解的特性,选择⁹³Nb、¹⁸¹Ta、¹⁸²W、¹¹⁸Sn为分析同位素及50 ng/mL¹⁸⁵Re为内标,建立了电感耦合等离子体质谱法(ICP-MS)同时测定地球化学样品中微量铌、钽、钨、锡的新方法。在选定的实验条件下,铌、钽、钨、锡质谱强度与其质量浓度在0.01～100 ng/mL范围内呈良好的线性关系,相关系数在0.999 6～0.999 8之间,方法检出限为0.003～0.090 ng/g,定量限为0.010～0.300 ng/g。将实验方法应用于岩石、土壤、水系沉积物标准物质中铌、钽、钨、锡的测定,测定值与认定值基本一致,相对标准偏差(RSD,n=9)分别在1.8%~4.9%、2.4%~5.3%、2.0%~5.3%、1.7%~4.9%之间。按照实验方法对岩石、水系沉积物、土壤实际样品中铌、钽、钨、锡进行测定,相对标准偏差分别在2.1%~4.1%、2.3%~4.0%、2.4%~4.2%、1.6%~4.3%之间。     

从废钨渣中酸法回收钽铌的研究

阐述了从废钨渣中酸法回收铌钽的新工艺,采用稀酸脱硅-浓酸脱铁、锰-HF酸浸出-蒸发浓缩工艺,可处理氧化钽和氧化铌含量分别为0.14%和0.59%的钨渣。通过实验确定了最佳的处理条件,在最优条件下可得到含氧化钽8.0 g/L和氧化铌35.4 g/L的HF酸溶液,该溶液可直接用于工业生产,钽和铌的回收率达到80%以上。该工艺既可实现钨渣中钽、铌、硅等资源的回收利用,又可减轻大量钨渣堆存引起的环境污染问题。     

波长色散X射线荧光光谱法测定钽铁和铌铁矿中钽铌铀钍

钽铁和铌铁矿中钽和铌含量直接关系到矿物资源的品位,铀和钍由于具有放射性,其含量也受到重点关注,但现有检测方法过程复杂,耗时较长。采用四硼酸锂和偏硼酸锂等质量比组成的混合熔剂,选择1∶20超低稀释比,以硝酸钡为氧化剂,采用高纯氧化物熔融制备人工参考样品,以铪和钼元素分别作为钽和铌的内标元素,铀和钍测定时不用内标,建立了波长色散X射线荧光光谱法(WDXRF)测定钽铁和铌铁矿中钽、铌、铀和钍含量的分析方法。结果表明,钽、铌、铀和钍各元素氧化物的检出限分别达到0.016%、0.006%、0.003%和0.004%,对应氧化物参考样品校准曲线线性范围较宽,相关系数分别达到0.999 9、0.999 9、0.999 1、0.999 3。选用实验方法测定钽铁和铌铁矿样品进行精密度试验,各元素对应氧化物测定结果的相对标准偏差(RSD,n=10)如下:五氧化二钽为0.062%~0.38%,五氧化二铌为0.046%~0.18%,八氧化三铀为0.26%~0.52%,二氧化铪为0.27%~1.1%。分别采用实验方法和电感耦合等离子体原子发射光谱法对钽铁和铌铁矿样品进行测定以进行方法比对,结果表明,两种方法测定结果基本一致。     

碱熔-电感耦合等离子体质谱法测定地质样品中铍铯镓铊铌钽锆铪铀钍

采用氢氧化钾碱熔法处理样品,以铑校正铍、铯、铊、铪、铀、钍,以铼校正镓、铌、钽、锆,建立了电感耦合等离子体质谱法测定铍、铯、镓、铊、铌、钽、锆、铪、铀、钍10种元素的方法。分别选用银坩埚、镍坩埚、刚玉坩埚熔融空白样品进行试验,结果表明,采用银坩埚时各元素的空白响应信号值与镍坩埚和刚玉坩埚相比均较低。对熔融条件进行了优化,确定熔融温度为600℃、熔融时间为8min。分别采用去离子水、2%(体积分数)硝酸上机测量,并记录各元素的响应信号值,与测定地质实际样品中各元素的响应信号值进行对比,结果表明,其对测定结果的影响可以忽略不计。在优化的实验条件下,各元素校准曲线线性相关系数均在0.9990以上,方法的检出限为0.023~0.049μg/g,测定下限为0.078~0.16μg/g。采用实验方法对岩石成分分析标准物质中铍、铯、镓、铊、铌、钽、锆、铪、铀、钍10种元素进行测定,测定结果与认定值基本一致,相对误差(RE)在-8.3%~9.6%之间,相对标准偏差(RSD,n=11)均不大于4.2%。采用实验方法对2个从野外采回的地质实际样品进行测定,并加入岩石成分分析标准物质进行加标回收试验,上述10种元素的回收率在96%~102%之间。     

江西雅山花岗岩体交代作用及其与稀有金属的成矿关系

根据雅山花岗岩体相带划分及岩体演化特征，论述岩体交代作用与Ta、Nb、Li、Rb、Cs等稀有金属的成矿关系．进而探讨矿床形成机制和成因类型。     

Thermodynamics of Interstitial Impurities Removal from Refractory Metals

Abstract

The applied thermodynamic aspects of removing hydrogen, nitrogen, oxygen, carbon, and silicon from vanadium, niobium and tantalum metals by pyrovacuum treatments are considered in this paper. Two major processes operate in refining by pyrovacuum treatment. One is distillation and the other is degassing. Distillation is mainly used to remove substitutional impurities that are either already present in the metal or have been added for removing any interstitial impurity. The success is determined by the partial pressure of the impurity element as well as by the difference in partial pressures of the impurity and the metal. The maximum rate of vaporization of impurity can then be estimated using the free evaporation equation. Interstitial impurities, particularly the gases hydrogen, nitrogen and oxygen, are removed by degassing. Thermodynamics of classical degassing, which is essentially the reverse of absorption, is described usefully by the pressure-composition isotherms. This is applicable mainly for the removal of hydrogen and nitrogen. The removal of oxygen, known as deoxidation, occurs by a more complex mechanism that involves the formation and evaporation of metal suboxides. Depending on the suboxide species responsible for deoxidation, the process is known as sacrificial deoxidation, carbon deoxidation, silicon deoxidation, or aluminium deoxidation. The applicability of these different processes to a particular metal, M is determined by the thermodynamic properties of the relevant M-Q, M-C-O, M-Si-O, and M-AI-0 system. It is shown in this paper that all the four processes are applicable to niobium and tantalum where as only aluminium deoxidation is useful for vanadium. For the removal of carbon and silicon also, the relevant deoxidation process can be used.