Intensification of zirconium and hafnium separation through the hollow fiber renewal liquid membrane technique using synergistic mixture of TBP and Cyanex-272 as extractant

The novel synergistic mixture of TBP and Cyanex-272 is used as the extractant in the hollow fiber renewal liquid membrane(HFRLM) technique for Zr/Hf separation.The effects of the chemical and operational parameters such as HNO3 concentration in the donor phase,NH4 F concentration in the acceptor phase,Cyanex-272 and TBP concentration in the liquid membrane phase,the lumen and shell side flow rates,and aqueous/organic volume ratio on the mass transfer and separation performance of HFRLM method were investigated.The obtained results reveal the intensification potential of proposed HFRLM technique for selective extraction of Zr over Hf with separation factor higher than 100.The HFRLM method provides two times higher mass transfer flux in comparison with hollow fiber supported liquid membrane(HFSLM).Also,the HFRLM method shows satisfactory stability for 700 min of continuous operation.The Zr ion transport through the LM phase follows the coupled co-transport mechanism and the diffusion in the renewal layer is recognized as the rate-controlling step in the HFRLM process.Moreover,the Zr mass transfer coefficient and molar flux in the HFRLM method are calculated in the range of 1×10^-8 to 8.4×10^-7 m·s^-1 and 4.9×10^-6 to 20.1×10^-6 mol·m^-2·s^-1,respectively.

Equilibrium and kinetic data of adsorption and separation for zirconium and hafnium onto MIBK extraction resin

The equilibrium and kinetics of methyl isobutyl ketone(MIBK) extraction resin for adsorption and separation of zirconium and hafnium were studied under the different conditions of acidity,initial total concentrations of zirconium and hafnium and temperature.The equilibrium data of both zirconium and hafnium are found to follow the Freundlich adsorption isotherm,and the Freundlich isotherm constants(KF) are 3.53 and 0.64 mg/g,respectively.The equilibrium data of zirconium also fit the Langmuir adsorption isotherm,and the saturation adsorption capacity(Qmax) and the Langmuir isotherm constant(KL)are 75.93 mg/g and-0.012 7 L/g,respectively.The obtained kinetic data of both zirconium and hafnium are found to fit the HO pseudo-second-order kinetic model,and the rate constants of pseudo-second-order equation(k2) are-0.019 and 0.41 g/(mg·min),respectively.Column tests show that the MIBK extraction resin could be used as efficient adsorbent material for separating hafnium from zirconium.

Study of Zirconium and Hafnium Separation by Solvent Extraction Technique from Nitric and Hydrochloric Solutions with Acid, Basic and Neutral Extractants

This paper describes the study of the extraction of Zr and Hf in nitric and hydrochloric media by solvent extraction technique using different types of extractants. The effect of the extractants DEHPA, IONQUEST?801 and CYANEX?272, TBP, CYANEX?923, PRIMENE?JTM, ALAMINE?336 and ALIQUAT?336 was investigated. For acid extractants in both nitric and hydrochloric media, a high degree of extraction was observed, although they had low selectivity in separating the metals. For the acid extractants also, it was not possible to strip the metals from the organic phase through acid solutions. In this case, a stripping solution with very high acidity would be required, and this is not viable. When the basic extractants were used, no metal extraction was observed under the conditions investigated, indicating no extractable anionic species in either media. The optimum zirconium/hafnium separation was achieved using an acidity of 7.0 mol?L?1, nitrate concentration of 9.2 mol?L?1 and 1.5 mol?L?1 of TBP. In these conditions, a separation factor of 12.6 was obtained.

Separation of hafnium from zirconium in hydrochloric acid solution with di(2-ethylhexyl)phosphoric acid by solvent extraction

The preparation of nuclear-grade zirconium and hafnium is very important for nuclear power. The separation of hafnium from zirconium in a hydrochloric acid solution by solvent extraction was investigated with di(2-ethylhexyl)phosphoric acid(D2 EHPA). The effects of hydrochloric acid concentration, extractant concentration,diluents, and temperature on the distribution coefficient of hafnium and zirconium were studied. The species extracted were ZrOA_2·2 HA and HfOA_2-2 HA. In this process, the separation factors varied with different diluents and followed the order octane > hexane > toluene > chloroform.A high separation factor value of 4.16 was obtained under the conditions of a solution containing 0.05 mol/L HCl and0.01 mol/L D2 EHPA for the separation of hafnium from zirconium. The extraction reaction was endothermic.

Sorption of Zr^(4+) and Hf^(4+) onto Hydrous Ferric Oxide and Their Fractionation Behaviors:An experimental Study

An experimental study was carried out on the sorption of tetravalent ions Zr4+ and Hf4+ onto hydrous ferric oxide (HFO) and their fractionation behavior during colloid/solution interaction. The sorption of the isovalent ions Zr4+ and Hf4+ onto HFO is nonlinear, and they are fractionated during the sorption and co-precipitation processes: Zr4+ is more affinitive for HFO than Hf4+. At pH<6, the Zr/Hf ratios in solid phase decrease sharply with increasing pH values, but keep unchanged at pH>6. In both cases, the sorption/desorption or particle/water reaction can significantly fractionate Zr/Hf in the surface environment of the Earth.

Optimization of ferroelectricity and endurance of hafnium zirconium oxide thin films by controlling element inhomogeneity

Ferroelectric thin films based on HfO2 have garnered increasing attention worldwide,primarily due to their remarkable compatibility with silicon and scalability,in contrast to traditional perovskite-structured ferroelectric materials.Nonetheless,significant challenges remain in their widespread commercial utilization,particularly concerning their notable wake-up effect and limited endurance.To address these challenges,we propose a novel strategy involving the inhomogeneous distribution of Hf/Zr elements within thin films and explore its effects on the ferroelectricity and endurance of Hf_(0.5)Zr_(0.5)O_(2) thin films.Through techniques such as grazing incidence X-ray diffraction,transmission electron microscopy,and piezoresponse force microscopy,we investigated the structural characteristics and domain switching behaviors of these materials.The experimental results indicate that the inhomogeneous distribution of Hf/Zr contributes to improving the frequency stability and endurance while maintaining a large remnant polarization in Hf_(0.5)Zr_(0.5)O_(2) ferroelectric thin films.By adjusting the distribution of Zr/Hf within the Hf_(0.5)Zr_(0.5)O_(2) thin films,significant enhancements in the remnant polarization(2Pr>35μC/cm2)and endurance(>109)along with a reduced coercive voltage can be achieved.Additionally,the fabricated ferroelectric thin films also exhibit high dielectric tunability(≥26%)under a low operating voltage of 2.5 V,whether in the wake-up state or not.This study offers a promising approach to optimize both the ferroelectricity and endurance of HfO_(2)-based thin films.

Solvent extraction of hafnium from thiocyanic acid medium in DIBK-TBP mixed system

A novel process for the separation of hafnium from thiocyanic acid medium using the mixture of diisobutyl ketone（DIBK） and tributyl phosphate（TBP） as the extractant was developed.This extraction process was investigated experimentally as a function of the amount of TBP added,acidity,zirconium and hafnium concentrations,salting-out agent,temperature,duration,respectively.The results show that hafnium is enriched in the organic layer and zirconium is in aqueous layer in DIBK-TBP system.Under the optimal technological conditions：TBP addition 20%（v/v）,aqueous phase acidity 3.0 mol/L,ammonium sulfate addition 0.8-1.25 mol/L,room temperature and extraction time 10 min,the separation factor of hafnium from zirconium is 9.3.

Adsorption behavior of Zr(IV) and Hf(IV) on a silica-based macroporous TODGA adsorbent

In order to separate Zr(IV) and Hf(IV) in acidic solution,several kinds of silica-based macroporous adsorbents were synthesized.Their adsorption selectivity for Zr(IV) and Hf(IV) in HCl solution was investigated,and the TODGA adsorbent for the two elements had the largest adsorption difference.The effects of acid type,HCl concentration,and temperature on the adsorption behavior of Zr(IV) and Hf(IV) onto the TODGA adsorbent were conducted by batch experiments.It was found that H+exhibited a quite strong influence on adsorption capacity of Zr(IV) and Hf(IV).Isotherm fitting showed that the Langmuir model agrees well with the experimental data.The thermodynamic parameters indicate that the adsorption processes for both elements are endothermic reactions.The TODGA adsorbent had the higher adsorption selectivity for Zr(IV) over Hf(IV) and could be promising for their mutual separation.

Nanometallocarbosilanes： Synthesis, Physicochemical Properties and Structure

Highly efficient synthesis methods have been developed and characteristics of nanometallocarbosilanes molecular structure were studied by the research team of GNIIChTEOS （State Research Institute for Chemistry and Technology of Organoelement Compounds）. Nanometallocarbosilanes were synthesized by thermal co-condensation of oligocarbosilanes and alkyl amides of refractory metals. Initial, intermediate and final products of side reactions were characterized by 1H, 13C, 29Si NMR （nuclear magnetic resonance）, IR （infra-red） spectroscopy, GPC （gel-penetrating chromatography）, TGA （thermal gravimetric analysis）, TEM （transmission electron microscopy）, SEM （scanning electron microscopy）, RES （X-ray phase analysis） and elemental analysis. The proposed synthesis method of nanometallocarbosilanes was lbund to produce fusable soluble organosilicon oligomers with homogeneous distribution of nanoscale （10-20 nm） metal particles in the oligomer matrix. A computational model of the group and elemental composition of nanometallocarbosilanes was developed; it was shown that they are molecular globules of near-spherical shape and rigid polycyclic structure. Thermochemical treatment of nanometallocarbosilanes leads to SiC-nanoceramics （a high yield of up to 75-80 mass%） modified by metal nanoparticles （20-30 nm） contributing to its stabilization. The application of preceramic oxygen-free nanometallocarbosilanes will make it possible to advance in solving the problem of ceramic composite materials with long-term resistance at temperatures above 1,500 ℃ in oxidizing environments.

电感耦合等离子体质谱(ICP-MS)法测定锆钛矿中的铪

锆钛矿中存在耐高温的锆、钛化合物,铪以类质同象进入锆矿物中,准确测定锆钛矿中的铪对选矿研究、矿物综合利用及工业生产有重要作用。通过考察锆钛矿成分及熔融方法,以碳酸钠-硼砂高温熔融锆钛矿,以178 Hf为分析同位素及185 Re为内标,使用电感耦合等离子体质谱法测定锆钛矿中含量不均的铪。结果表明,碳酸钠-硼砂高温熔融效果最好,可完全溶解耐高温难分解的锆钛矿,当碳酸钠-硼砂质量配比为2∶1时熔融效果最佳。ICP-MS蠕动泵转速为45 r/min、雾化气流量为1.06 L/min时雾化效率最优。在选定的实验条件下,HfO_(2)质谱强度与质量浓度在0.01~250 ng/mL呈良好的线性关系,相关系数为0.9997,背景等效浓度为0.029 ng/mL,方法检出限为0.0032 ng/mL。按实验方法对中国国家标准物质中的HfO_(2)进行测定,测定值与认定值一致,相对标准偏差在1.6%~3.2%。按实验方法对锆钛矿样品中的HfO_(2)进行测定并进行加标回收实验,测定结果的相对标准偏差(RSD,n=9)为0.90%~3.4%,加标回收率在96.0%~106%,满足国家地质矿产行业标准DZ/T 0130—2006的要求。

锆合金腐蚀与防护研究进展

锆合金以其优异的核性能和生物相容性被广泛应用于民用发电反应堆、核动力航空母舰、核潜艇、空间飞行器的结构材料以及医用材料,在苛刻环境下服役的锆合金同样面临腐蚀失效的风险。由于材料本身服役环境的特殊性,使得锆合金腐蚀研究的模拟测试难度加大,诸多疑问难以得到有效解答。锆合金的腐蚀形式包括均匀腐蚀、疖状腐蚀、应力腐蚀以及微生物腐蚀,其腐蚀也受材料成分、热处理工艺、表面粗糙度、氧化膜成分、溶液的pH值、辐照、热流水化学环境以及温度等因素的影响,防护措施包括涂层和缓蚀剂等方式。为进一步改善锆合金的耐蚀性能,未来可从以下几方面展开研究:1)锆合金基体中固溶元素的浓度;2)第二相元素类型、晶粒尺寸及分布;3)氧化膜的生长机制;4)细菌附着方式和生物被膜生长行为等。

R60702锆激光焊接接头焊缝区的显微组织及其在硫酸中的耐蚀性研究

为探究不同焊接工艺下(工艺1:激光功率1 600 W,焊接速度1 600 mm/min,线能量60 J/mm,气体流量20 L/min,离焦量0 mm;工艺2:激光功率1 800 W,焊接速度1 200 mm/min,线能量90 J/mm,气体流量20 L/min,离焦量0 mm)R60702激光焊接接头中焊缝区不同组织的耐蚀性,采用金相显微镜(OM)、X射线衍射仪(XRD)、电化学测试仪、扫描电镜(SEM)、三维轮廓仪和能谱(EDS)对其金相组织、物相组成、耐腐蚀性能及机理、腐蚀形貌、腐蚀产物元素组成进行分析。结果表明:2种焊接工艺下的焊缝区呈现出不同的显微组织,工艺1条件下焊缝区为篮网状组织及少量(26.7%)平行板条状魏氏组织的混合,工艺2条件下焊缝区呈现出典型的魏氏组织。在100℃的20%硫酸中浸泡腐蚀72 h后,混合组织焊缝表现为电偶腐蚀,平行板条状魏氏组织焊缝表现为均匀腐蚀,平行板条状魏氏组织焊缝的耐蚀性更优。这是由于混合组织焊缝的显微组织不均匀性形成了电位差,导致氧化膜因电偶腐蚀发生破裂,因此其耐蚀性较差;而平行板条状魏氏组织焊缝的电化学均匀性良好,自腐蚀电位无显著差异,有利于抑制电偶腐蚀。

测定地质样品中铌、钽、铪、锆不同分析方法的比较

研究了不同酸溶、碱融测定地质样品中铌、钽、铪、锆的前处理方法,利用电感耦合等离子体发射光谱法、电感耦合等离子体质谱法进行测定。选用不同种类地质样品标准物质进行了条件实验,并分析了敞口酸溶、密闭消解、碱融三种不同分析方法的优劣点,供不同实验条件的实验室进行选择。采用硝酸-氢氟酸-过氧化氢体系密闭消解酸溶ICP-MS检测的方法能很好地测定铌、钽、铪、锆,相对标准偏差(RSDn=12)小于4%,并应用于尼日利亚高山州ZURAK地区一批实际样品的分析检测,取得了较好的效果。

工业生产中Zr702锆卷MIG焊接工艺

应用光学显微镜(OM)、扫描电镜(SEM)和能谱仪(EDS)等技术对不同焊接工艺条件下的Zr702卷MIG焊接接头的组织及性能进行了研究和分析。结果表明,工业纯锆Zr702在MIG焊接过程中高温下的焊缝熔池和热影响区容易受到空气污染,吸收空气中大量的氧气,氧原子以间隙原子形式固溶在锆基体中,造成晶格畸变,内应力变大,恶化焊接接头性能;采用尾部拖罩保护,可以有效保护焊缝免受空气污染,得到力学性能良好的焊接接头;被空气污染的焊缝颜色为灰黑色,而惰性气体保护良好的焊缝颜色为银白色;在工业纯锆Zr702焊接过程中,热影响区会产生马氏体相变,小电弧电压、快焊接速度可以得到晶粒尺寸较小的板条马氏体;在工业纯锆Zr702焊接时,采用尾部拖罩保护、在保证焊缝成形的基础上采用小电弧电压、快焊接速度可以得到力学性能良好的焊接接头。

A simple method for determining Hf in Zr and Zr alloys by ICP-AES

This paper describes a rapid, accurate and precise method for determination of trace hafnium (Hf) in zirconium and zirconium alloys by inductively coupled plasma atomic emission spectrometry (ICP-AES). It was found that using a mixture of sulfuric acid (H2SO4) and ammonium sulfate (NH4)2SO4, the total sample dissolution time was 15 min. Experimental works revealed that a high Zr concentration would result in a significant decrease in the peak height of the analyte lines, which was corrected by standard addition method. The performance of the developed method was evaluated by calculating the recovery percent and using standard reference material analysis. The recoveries were in the range of 97.6%-99.5% and the relative standard deviations were within 0.8%-3.0%. The detection limit (3σ) of Hf was found to be 0.01 μg·g-1, respectively. The proposed technique, with high precision and accuracy, was applied to the analysis of trace Hf in zirconium-niobium ingots and tubes for the first time in Iran.

Application of Multi－objective Optimization Method to Extracton Separtion Process

A multi-objective decision procedure was proposed to select the optimal precase parameters of extractionseporating zirconium and hafnium from sulphuric acid solution with Alamine-336 as an extractant in this pa-per.Adaptive Random Search(ARS) algorithm was adopted for optimizing calculation. The results obtainedshow that the multi-objective decision method is much better than sangle-objecive decision method.

Recent Research Progress on ZrB_2-and HfB_2-based Ceramics

The strong covalent bonding characters of zirconium diboride（ Zr B2） and hafnium diboride（ Hf B2） with natural hexagonal Al B2-type crystal structure give them high melting points（ 〉 3 200 ℃）, high bending strength, high elastic modulus and high hardness.Zr B2- and Hf B2-based ceramics are promising candidates for the thermal protection components of propulsion systems,rocket nozzles,sharp leading edges and nose cones. This paper introduces the recent research progress on Zr B2- and Hf B2-based ceramics,including the synthesis methods of the boride powders,the sintering methods of the boride-based ceramics and their properties.The advantages of different synthesis methods and sintering methods are compared. The influence factors on the mechanical properties,oxidation resistance and thermal shock resistance are summarized.

澳大利亚锆矿产业发展及其产业政策分析

锆是一种重要的稀有金属,广泛应用于各种工业领域。澳大利亚是全球锆资源的主要生产国。本文分析了澳大利亚锆矿产业发展形势及未来发展趋势,进而分析了澳大利亚锆矿产业政策。分析发现,澳大利亚拥有全球最大的锆矿石生产企业以及先进的工艺技术,锆矿产业发展形势较好,其对国际锆矿市场具有较大的影响力。此外,澳大利亚非常注重制定和实施锆矿产业政策。这些政策主要包括锆矿产业勘查政策、投资政策以及可持续发展政策,这些产业政策在提高澳大利亚锆矿产业的国际竞争优势方面发挥了较大的作用。最后,文章在启示分析的基础上提出了三个方面促进我国锆矿产业发展的相应对策建议,即大力推进锆资源储量调查,努力提高选冶技术研究;加强海外战略性矿产布局,加快矿业“走出去”步伐;打造锆矿产业全产业链,促进我国锆矿产业健康发展等等。

热氧化温度对预喷丸R60702表面氧化层及耐蚀性影响研究

对预喷丸工业纯锆R60702分别在450、550、650和750℃进行2 h的空气热氧化处理后,测试了氧化层厚度、纳米硬度和在15wt%的H2SO4溶液中的电化学腐蚀行为。结果表明,氧化层厚度随温度的升高而逐渐增大;氧化层截面纳米硬度在650℃氧化温度下最高,可达17.98 GPa;与喷丸试样相比,预喷丸+热氧化试样在15wt%H2SO4溶液中表现出良好的耐腐蚀性能;650℃氧化2 h为工业纯锆R60702的最优热氧化工艺。

核级锆铪溶剂萃取分离研究进展

核级锆铪的制备是核工业安全快速发展的重要保障,锆铪深度分离是关键。锆铪分离的方法分为火法和湿法两大类。工业上获得核级锆铪的主要方法是溶剂萃取,萃取分离体系主要有甲基异丁酮(MIBK)-硫氰化氢(HSCN)、磷酸三丁酯(TBP)-硝酸(HNO 3)和三辛基胺(TOA)-硫酸(H 2SO 4),但都存在萃取效率低、萃取剂用量大、环境污染严重等不足。学者们一直致力于开发绿色高效的锆铪分离型新萃取体系,如胺类萃取剂、中性膦类萃取剂、有机膦/磷酸类萃取剂、羟肟酸类萃取剂、协同萃取体系等。以优先萃取锆/铪为切入点,从优先萃锆体系和优先萃铪体系两个方面阐述不同萃取体系萃取分离锆铪的机理、性能及优缺点,为锆铪萃取分离提供新思路。